A systematic revision of Tatia ( Siluriformes : Auchenipteridae : Centromochlinae )

The auchenipterid catfish genus Tatia is revised. Twelve species are recognized including three described as new. Tatia is diagnosed by the hyomandibula elongated anterodorsally, the anal-fin base of adult males reduced in length, and the caudal peduncle laterally compressed and deep with a middorsal keel. Tatia aulopygia occurs in the Madeira river drainage and is distinguished by the reduced cranial fontanel in adults and male modified anal fin with middle rays reduced in length. Tatia boemia, known from the upper Uruguay river drainage, is distinguished by its unique color pattern with dark chromatophores on the sides of body. Tatia brunnea from river basins in Suriname and French Guiana and the Negro river drainage, Amazon basin, is recognized by its wide head and mouth and by the male modified anal fin with sharply pointed tip. Tatia dunni, from the upper Amazon basin, is recognized by its narrow head, long postcleithral process in some specimens, and body coloration with irregular blotches or stripes. Tatia galaxias, endemic to the Orinoco river basin, is distinguished by its large eye and short snout. Tatia gyrina, distributed in the upper and central Amazon basin and in northern Suriname, has a uniquely reduced mesethmoid, slightly protruding lower jaw, second nuchal plate with slightly concave lateral borders, third nuchal plate reduced, small prevomer, low number of ribs, low number of vertebrae and sexual dimorphism regarding intumescent male genital papilla. Tatia intermedia, recorded from central and lower Amazon basin, Tocantins river, and coastal drainages in Guyana, Suriname, French Guiana, and eastern Pará State, Brazil, is distinguished by the short postcleithral process, small eye and long snout. Tatia neivai, from the upper Paraná river, Paraguay river and upper Paraíba do Sul river basin, is distinguished by its unique vertebral count and caudal-fin coloration consisting of transverse dark bars. Tatia strigata, from central Amazon basin and Negro river, is distinguished by its horizontally striped color pattern and the modified male anal fin with middle rays reduced in length. Tatia caxiuanensis, a new species described from the Curuá river, lower Amazon basin, is recognized by its wide cranial fontanel and distinctive anal fin in mature males. Tatia meesi, a new species described from the Essequibo river basin, Guyana, is distinguished from congeners by the cranial fontanel with two separate openings and thin nasal bone. Tatia nigra, a new species described from the central Amazon basin, is distinguished by its short postcleithral process, low number of vertebrae, and dark color pattern. All twelve species of Tatia are described or redescribed and a key to species is provided.

Tatia comprises a group of relatively small (20-150 mm standard length), nocturnal auchenipterids [or centromochlins] that feed on small fruits and invertebrates (H. A. Britski, M. Goulding, pers. comm.).They are endemic to South America east of the Andes and are present in most of major drainages, including the Orinoco, Amazon, Paraná-Paraguay, and Uruguay, as well as northern coastal rivers from the Essequibo to Amapá State and Marajó Island, Brazil.Tatia is absent in the São Francisco river basin and small riverine basins along the Brazilian east coast.Tatia is the most speciose genus in the subfamily, with 12 species recognized here (Table 1).Tatia species occur in lentic sections of igarapés, rivers, and lakes, where they remain hidden in submerged trunks or rocky crevices during the day and emerge only at night to forage (Lowe-McConnell, 1964, 1975, 1987;Soares-Porto, 1995).At night, individuals of Tatia usually remain close to the surface near river banks or in the middle of the river, swimming in a very peculiar way (fast and erratic), and capturing fallen insects (F.C.T. Lima, pers.comm.).Some species occur in black water rivers, but none are restricted to these environments.Many members of the genus are beautifully colored and, consequently, very attractive to the ornamental fish trade.Tatia species, however, are not well suited for captivity because of their apparent intolerance for low oxygen conditions.Most do not survive transport to Europe and North America (Sands, 1984).
The generic name Tatia was proposed by Miranda Ribeiro (1911: 360) for Charles Tate Regan of the British Museum of Natural History, London, in honor of his many contributions to the knowledge of the South American freshwater fishes.The group was erected to include two species previously ascribed to Centromochlus: Tatia intermedia (Steindachner) and T. aulopygia (Kner), based on the presence of a genital papilla over the anterior anal-fin rays (Miranda Ribeiro, 1911:353).After Miranda Ribeiro's (1911) description the name Tatia was mentioned only in catalogues (e.g.Gosline, 1945) and practically forgotten.Subsequent authors such as Eigenmann & Allen (1942) and Fowler (1945a) described new species in the genus Centromochlus, without mentioning Tatia.Boeseman (1953) referred to Tatia, but described a new species as Centromochlus creutzbergi.Britski (1972) considered Tatia to be a junior synonym of Glanidium Lütken due to similarities of sexually dimorphic features.In his study of auchenipterids primarily from Suriname Mees (1974) redescribed Tatia and expanded the genus to 14 species, six of which he described as new: T. brunnea, T. concolor, T. galaxias, T. punctata, T. reticulata and T. simplex.Four additional species of Tatia have been described subsequently (Mees, 1988;Royero, 1992;Soares-Porto, 1995;Koch & Reis, 1996).
The present paper gives a reappraisal of Tatia based on examination of numerous specimens in addition to those available to previous authors.Patterns of variation within and between species are considered throughout their distributions.

Material and Methods
Osteological features were examined in cleared and stained (CS) specimens prepared according to the procedures of Taylor & van Dyke (1985).Prior to clearing and staining, specimens were dissected when possible to determine gut contents, sexual maturity of gonads, and record myological information.Osteological data from some types or specimens poorly represented in ichthyological collections were obtained from radiographs (noted as "R" in the Material Examined section).Nomenclature of osteological elements follows The Zebrafish Information Network (ZFIN).Muscle names follow Sarmento- Soares & Porto (2006).Drawings were rendered from digital photographs prefereably of cleared and stained specimens.Straight-line measurements were made with a digital caliper, and recorded in tenths of a millimeter.
Measurements included: standard length (SL, from snout tip to caudal-fin base); body depth (on nuchal shield, from origin of dorsal-fin spine to the belly); body width (widest distance between lateral surfaces of cleithra, taken between anterior-most margin of cleithral bone beneath pectoral-fin origin); caudal-peduncle depth (least distance between dorsal and ventral surfaces of caudal peduncle); caudal-peduncle length (from base of posterior-most anal-fin ray to point coinciding with origin of lower unbranched caudal-fin ray); predorsal length (from snout tip to origin of dorsal fin); preanal length (from snout tip to anal-fin origin); prepelvic length (from snout tip to pelvic-fin origin); dorsal-fin origin to pectoral-fin origin; dorsal-fin origin to pelvic-fin origin; pectoralfin origin to pelvic-fin origin; prepectoral length (from snout tip to pectoral-fin origin); dorsal-fin base (from origin of dorsal-fin spine to posterior-most base of dorsal-fin insertion); adipose-fin base (from origin of adipose fin fold to its posterior-most base); anal-fin base (distance between genital opening and posterior-most base of anal-fin insertion, measured under the same criteria for both males and females); dorsalfin spine length (from base of spine to its distal tip); pectoralfin spine length (from origin of spine to its distal tip, taken with the spine erected); postcleithral (humeral) process length (from anterodorsal margin of exposed process to posteriormost tip of process); first branched pelvic-fin ray (from base to tip of first branched pelvic-fin ray); longest anal-fin ray (from base to tip of first branched anal-fin ray); head length (HL, from snout tip to bony end of opercle); head width (between dorsalmost extents of opercular openings); snout depth (distance in median sagittal plane between posterior nostril and midventral contour of body); interorbital distance (least distance between dorsalmost margins of bony orbit); left internarial width (between left anterior and left posterior nostrils); anterior internarial distance (transverse distance between anterior nostrils); posterior internarial distance (transverse distance between posterior nostrils); snout length (from snout tip to anteriormost margin of eye); maxillary-barbel length (from base to tip, with barbel retracted); outer mentalbarbel length (from base to tip, with barbel retracted); inner mental-barbel length (from base to tip, with barbel retracted); orbital diameter (greatest horizontal dimension of eyeball); mouth width (between corners of closed mouth).
Counts of fin rays and bony elements were obtained from alcohol-preserved and cleared and stained specimens.Vertebral counts included all rib-bearing centra but did not include any of the anterior, complex centrum elements without ribs, following Ferraris & Fernandez (1987), and included the compound caudal centrum (PU1+U1) as the last element.Hemal spine counts accompany the numbers for correspondent vertebra, as shown in Fig. 1.Count of branchiostegal rays were done only in cleared and stained specimens.The direction of dorsal and pectoral-fin spine serrations are referred to as anal-fin segmented rays (lepidotrichia) may have adjacent segments with curved border, forming denticulations herein refered to as antrorse or retrorse.
Diagnosis.Tatia is distinguished among the Centromochlinae by three uniquely derived features.The hyomandibula is elongate anterodorsally, not contacting the narrow metapterygoid and, instead, connected only to the trapezoidal quadrate (Fig. 2); anal-fin base of adult males is reduced (anal-fin base length 3.3-8.0%SL); and caudal peduncle is compressed and deep (caudal-peduncle depth 10.1-18.6%SL), with a middorsal keel posterior to adipose fin.

Generic description.
Tatia comprises species with somewhat robust head; caudal peduncle much compressed laterally and deep; well-developed adipose eye lid; eye moderately large, and latero-dorsally located.Following characters used to distinguish species of Tatia (illustrations based on T. gyrina): Head: cranial fontanel always present (Fig. 3, fo); premaxilla transversely elongated, meeting its counterpart medially; autopalatine tubular, oriented obliquely to longitudinal axis of body; maxilla very small, shorter than or same length as autopalatine; three nuchal plates present (Fig. 3,n1,n2,n3).Epioccipital process small, connected to third nuchal plate by ligaments (Fig. 3, pe).Mullerian ramus with distal tip shaped as slightly curved disc, its concave face superficially adjoined to anterior wall of gasbladder.Prevomer usually with well developed arrow-shaped lateral processes or with short lateral process.Prevomerian teeth present in T. galaxias and T. intermedia.
Lateral line system: Infraorbital 1 short, with ventro-lateral process either clearly restricted to anterior border of eye or almost reaching ventral border of eye; infraorbitals thin and canalicular, forming incomplete or complete infraorbital series.Lateral line on body straight, inconspicuous, with ossified canal bones just anteriorly.
Fins: Dorsal fin with major spine preceded by small dorsal locking spine and followed by 3-5 branched rays; pectoral fin with one spine plus 3-5 branched rays; pelvic fin with one unbranched plus 5 branched rays, margin rounded; adipose fin above anal-fin base; anal fin with 3 unbranched plus 6-8 branched rays; caudal fin with 8+9 principal rays, forked, lobes with rounded tips; dorsal caudal-fin lobe slightly elongate in males of some species.

Sexual dimorphism. In catfishes of subfamily
Centromochlinae the anal fin of sexually mature males is modified into a sperm conductor with the anal-fin rays and proximal radials directed posteriorly, aligned nearly parallel to vertebral axis (Ferraris, 1988;Soares-Porto, 1998).In mature males the anal fin is strongly modified such that it is supported by enlarged and joined proximal anal-fin radials (Ferraris, 1988;Soares-Porto, 1998) and by partially ossified distal radials.Anal-fin proximal radials are associated with the thickened and lengthened hemal spines of adjacent vertebrae.Modified male anal fin has three developed unbranched rays.The first unbranched ray is shortest, about one-quarter length of second unbranched ray, and with segments fused (except in T. brunnea).Some species have the first unbranched anal-fin ray preceded immediately by a tegumentary keel.The second and third unbranched rays are thick.In the Centromochlinae, Tatia is the only genus with species that bear segments that curve outwards, forming antrorse denticulations along the anterior margin of the third unbranched anal fin ray in adult males.
The monophyly and interrelationships among species of Tatia were hypothesized by Soares-Porto (1998), who considered the clade T. gyrina plus T. creutzbergi as sister to all other Tatia species.
Inseminating reproductive mode (sensu Burns et al., 1997) has been documented within the Auchenipteridae (von Ihering, 1937;Loir et al., 1989;Meisner et al., 2000).In the centromochlin catfishes, inseminating is supposed to take place (Loir et al., 1989;Franke, 1990), but a reproductive behavior is not yet reported.During reproductive phase, the anal-fin rays change their position probably channeling for discharge of seminal ducts, acting as a sperm conductor during reproduction.Such a morphological change was observed in some males of Centromochlus romani and also in T. nigra.The sperm probably runs along the spoon shaped anal-fin rays, and the fish may press the fin against the belly of the female, for inseminating.Morphological evidences suggesting inseminating reproductive mode in Tatia are the intumescent female genital papilla (as in T. gyrina and T. nigra) and the spoon-shaped laterally curved male anal fin (observed in T. nigra).A detailed analysis of morphological changes of the reproductive tract needs to be accomplished by histological preparations, and is out of the scope of present contribution.
Distribution.Species of Tatia are broadly distributed in the regions east of the Andean Cordilleras (Fig. 6).Tatia ranges from the Guarapiche river, Orinoco basin, in Venezuela, to the Pelotas river, Uruguay drainage, in Brazil.The group is found in major continental river basins, such as the Amazon, Orinoco and Paraná-Paraguay; as well as in the Essequibo and small coastal drainages in French Guiana, Suriname and Amapá and Marajó island in northern Brazil.Although well distributed in cis-Andean South America, the group is not known from certain drainage basins, including the São Francisco and small coastal river drainages of northeastern and far eastern Brazil.Tatia is found, however, in headwaters of Paraíba do Sul basin, São Paulo State.The absence of Tatia from certain areas may be a function of inadequate collections from those river basins or may reflect actual disjunct distributions of the group as whole.
Diagnosis.Tatia aulopygia is distinguished from all other species of Tatia by having a short cranial fontanel, with the opening restricted to the frontals (Fig. 8); a genital papilla with thick flap of skin around the deferent duct in males (Fig. 9); and a notched anal fin in adult males (Fig. 9).The species also is distinguished from congeners by a combination of characteristics: nasal bone partially sutured to lateral margin of mesethmoid; anal fin with 7-8 branched rays; 10-11 ribs; 38-39 post-Weberian vertebrae.Additional features useful for distinguishing this species include: third nuchal plate well projected laterally with curved tip; and caudal-fin lobes of mature females similar in length, but mature males with slightly elongated upper lobe.premaxilla underneath with synchondral articulation; cranial fontanel short, ovoid, bounded by frontal (Fig. 8); nasal ossified with wide medial flanges partially sutured to lateral margin of mesethmoid; autopalatine tubular, oriented obliquely to longitudinal axis of body; maxilla very small, shorter than autopalatine; prevomer expanded anteriorly with well developed arrow-shaped lateral processes; jaws of equal size; premaxilla and dentary with four to five rows of conical teeth.First nuchal plate somewhat pentagonal; second nuchal plate deeply concave along lateral margin; third nuchal plate curved, projected laterally.Epioccipital process small.Suspensorium, hyoid arch and opercular bones as in generic description.Suprapreopercle present as short robust canal bone.Six branchiostegal rays articulated with hyoid arch: four with anterior ceratohyal and two with posterior ceratohyal.
Four infraorbital bones in incomplete series.Infraorbital 1 broad with short ventro-lateral process on anterior border of eye; remaining infraorbitals thin, reduced to canalicular portions.Infraorbital 2 smallest, close to infraorbital 1, followed by non-ossified portion of canal below eye and two posterior canal bones, one long and one short, forming posterior orbital rim.Lateral line on body with ossified canal bones posteriorly to vertical through pelvic-fin origin.Dorsal fin I,5 (n=7); dorsal-fin spine with 14-16 antrorse serrations along entire anterior margin; posterior margin smooth.Pectoral fin I,5 (n=7); pectoral-fin spine with 21-24 antrorse serrations along anterior margin; small serrations close to spine base; 14-16 retrorse serrations along posterior margin; serrations along both margins progressively larger toward spine tip.Pelvic fin i,5 (n=7); margin rounded.Adipose fin small, origin on vertical through end of anal-fin base.Anal fin iii,7-8 (n=7); anal-fin pterygiophores in eight rod-like proximal radials and seven cartilaginous distal radials.Caudal fin forked, lobes with rounded tips, 8+9 principal rays, 18-20 upper procurrent, 17-20 lower procurrent rays (n=7).Pleural ribs 10-11 attached to consecutive vertebrae.Post-Weberian vertebrae 38-39 (n=4).Color in alcohol.Head and body mottled with dark and light brown patches of pigmentation, sometimes forming faint blotches irregularly distributed over sides of body (Fig. 7).Lips and chin dark brown.Dorsal fin dark brown, pectoral fin usually pale brown or not pigmented.Adipose fin pale brown, caudal fin usually with transverse bars but young specimens with whitish spots.Pelvic fins and belly whitish.
Color variation.Body coloration in T. aulopygia is somewhat variable, usually with large bands or blotches irregularly distributed over sides of body.In some specimens coloration is uniformly dark or pale brown, with caudal fin mottled.Some young specimens have small spots over ventrolateral parts of body and a barred caudal fin.Mees (1974) noted the presence of longitudinal pale streaks on the body and observed irregular patches of pigmentation on specimens from the Guaporé river, but all specimens available to him are now very faded and unsuitable for accurate description of coloration.Recent expeditions to the Guaporé river provided more adult specimens of T. aulopygia, on which the above description is based.
Sexual dimorphism.Based on examination of gonads, T. aulopygia attains sexual maturity above 80 mm SL.In mature females a genital papilla is not evident.The genital papilla of mature males is visible, with a thick skin flap around the deferent duct.The anal fin of mature males (Fig. 9) is strongly modified, with the three unbranched and first two branched rays enlarged and thickened.The first unbranched anal-fin ray is immediately preceded by a tegumentary keel.The second unbranched ray is intermediate in size between the neighboring first and third rays.The third unbranched ray is the longest, forming a minute pointed fin tip (Fig 9,uiii); distal segments are smaller, and antrorsely curved (Fig. 9, ac).The first branched ray is slightly curved towards the fin tip, bearing retrorsely curved distal segments (Fig. 9, rc).The fourth and fifth branched rays are shorter, forming a central notch in distal margin of the anal fin.The posterior branched rays are normally developed and not reduced.
The hemal spines interdigitating with anal-fin pterygiophores are thick in males; but those hemal spines are undifferentiated in females.Caudal-fin lobes are of comparable length in mature females, whereas upper lobe is more elongated in mature males.
Specimens of T. aulopygia historically housed in collections are mostly juveniles, with only one syntype bearing a modified anal fin.Information on male anal-fin morphology was improved by recent captures of adult specimens in the Amazon basin.Diagnosis.Tatia boemia is distinguished from other species of Tatia by its unique color pattern of dorsum and dorsolateral sides greyish-brown with small dark chromatophores.
Chromatophores become sparse and faint towards the ventral portion of the body (cf.Koch & Reis, 1996).The species is also distinguished by the following combination of characters: nasal ossified with wide medial flanges partially sutured to lateral border of mesethmoid; pectoral fin with four branched rays; ribs attached to consecutive post-Weberian vertebrae; with two vertebrae alternatingly unribbed and ribbed (Fig. 1).Additional features useful for distinguishing species include: first nuchal plate somewhat elliptical to rounded; eye 17.4-22.8%HL; caudal-fin lobes of equal length in mature females, upper lobe slightly elongated in mature males; number of vertebrae 34.
Description.Measured adult specimens 52.4-64.5 mm SL; morphometric data presented in Table 3. Body slim, head slightly depressed dorso-ventrally.Head large, robust, outline of head in dorsal view elliptic, broader than long.Dorsal outline of trunk from dorsal-fin base to caudal peduncle gradually compressed posteriorly.Lateral profile of head from snout tip to above opercular margin slightly convex to pectoral-fin insertion.Ventral profile of head and abdomen flat.Ventral profile of body concave posterior to anal fin.Head integument thin, cranial roof visible; well-developed adipose eye lid; eye latero-dorsally located in anterior portion of head; mouth terminal, upper lip extended posterolaterally as well-developed fleshy rictal fold; snout margin rounded; anterior nostril tubular, located on anterior border of snout, above lip; posterior nostril large, rounded, limited by small skin flap; transverse distance between anterior nostrils slightly shorter than distance between posterior ones.Maxillary barbel moderate in size, extending beyond posterior tip of postcleithral process, reaching vertical through middle of dorsal fin; four mental barbels, tips not reaching pectoral-fin base, arranged in arc along ventral surface of jaw; inner mental barbel about 50.0-61.0%length of outer mentals.Postcleithral process well developed, almost reach- Rostral border of cranium broad with large mesethmoid; premaxilla underneath with synchondral articulation; cranial fontanel narrow, elliptical, bounded by mesethmoid and frontal (Fig. 11); nasal ossified, with medial flanges partially sutured to lateral margin of mesethmoid; autopalatine tubular, oriented obliquely to longitudinal axis of body; maxilla small, shorter than autopalatine; prevomer expanded with well developed arrow-shaped lateral processes; jaws of equal size; premaxilla and dentary with three to four rows of conical teeth; first nuchal plate somewhat elliptical; second nuchal plate laterally concave, partially in contact or not with supraoccipital; third nuchal plate relatively straight, projected laterally.Epioccipital process small.Suspensorium, hyoid arch, branchial skeleton and opercular bones as in generic description.Suprapreopercle present as short canal bone.Six branchiostegal rays articulated with hyoid arch: four with anterior ceratohyal and two with posterior ceratohyal.Branchial skeleton as for genus.Basibranchial 2 forming osseous rod with broad cartilaginous anterior tip, separated from shorter basibranchial 3.
Six infraorbital bones in complete series.Infraorbital 1 broad, with moderately developed ventro-lateral process, around anterior border of eye; remaining infraorbitals thin, reduced to canalicular portions.Infraorbital 2 smallest, close to infraorbital 1, followed by three elongate canal bones, forming bottom orbital rim; infraorbital 5 small, forming posterior orbit.Lateral line on body with ossified canal bones until vertical through pelvic fin.

Color in alcohol.
Color pattern diagnostic within Tatia, as stated in the original description by Koch & Reis (1996): Dorsal surface of head, back and upper sides, greyish-brown with many chromatophores surrounding small lighter (depigmented) areas; sides becoming paler ventrally as chromatophores become progressively more widely spaced; lower sides and ventral surfaces yellowish.Dorsal-fin spine dark.Lips, anterior nostril and chin whitish.Barbels, posterior part of nuchal shield, pectoral, pelvic, anal, and adipose fins unpigmented.Caudal fin largely pale with small dark spots.

Sexual dimorphism.
Based on examination of gonads, T. boemia attains sexual maturity above 52.4mm SL.In mature females a genital papilla is not evident.In mature males a genital papilla is visible, thick, with a short deferent duct.The anal fin of the mature males (Fig. 12) is strongly modified with the three unbranched and first branched rays enlarged and thickened.The first unbranched ray is non-segmented and shortest, about half-the length of second unbranched ray (Fig. 12).First unbranched anal-fin ray is immediately preceded by a tegumentary keel (Fig. 12, tk).The second unbranched ray has an intermediate size between the neighboring first and third rays.Third unbranched and first branched are the longest rays forming a fin tip (Fig. 12, uiii).Third unbranched with the three distal segments smaller, antrorsely curved (Fig. 12, ac).First branched ray with four distal segments retrorsely curved (Fig. 12, rc).The posterior branched rays are progressively shorter.
The hemal spines 15-17 are associated with anal-fin pterygiophores in males and become thick during maturity.Female hemal spines 15-18 are associated with pterygiophores and undifferentiated (Fig. 1).
There is a discrete sexual dimorphism regarding the caudal-fin margin in mature males of T. boemia.The upper caudal-fin lobe is slightly elongate, about 10.0% longer than the lower lobe, whereas mature females have equal lobes.
Distribution.Tatia boemia is endemic to upper reaches of the Uruguay river drainage (Fig. 6).It is the most southernly dis-   tributed species of Tatia.Together with T. neivai both are the only species inhabiting the La Plata basin (Koch & Reis, 1996).
Remarks.Tatia boemia is the only auchenipterid catfish listed in Brazil as an endangered species (Ministério do Meio Ambiente, 2004).As it is a typically nocturnal catfish, the local people call T. boemia under the common name "boa noite", meaning good night (Walter R. Koch, pers. comm.).
In T. boemia the first (anterior) nuchal plate is variable in size.First nuchal plate is sometimes assymmetrical, permiting contact between supraoccipital and second nuchal plate (as in Fig. 11), or symmetrical, bordered by supraoccipital and second (middle) nuchal plate.We observed variation in first nuchal plate size in other auchenipterid species, such as Centromochlus perugiae and Glanidium leopardus.Anterior (first) nuchal plate either fully developed or reduced is reported in a few doradid species as Oxydoras niger and Doras fimbriatus (Birindelli et al., 2007: 680), and the species are considered polymorphic regarding this character.Polymorphism seems to be also the case in the above mentioned auchenipterids including T. boemia.
Tatia boemia is presumed to be sister to T. neivai, both sharing the presence of a single vertebrae without ribs preceding the last ribbed vertebrae (character 17, fig. 14 of Soares-Porto, 1998).This ribless vertebra (number 9 in T. neivai, 10 in T. boemia) has each transverse process with a reduced costal facet.The last rib pair is small and attached to the hemal arch of vertebra 10 (T.neivai) or 11 (T.boemia).In all other Tatia species the ribs are attached to consecutive post-Weberian vertebrae.
Diagnosis.Tatia brunnea is distinguished from its congeners by the male anal fin with sharp pointed tip; the first unbranched anal-fin ray divided into 3-4 segments; and the last branched ray reduced (Fig. 15).Tatia brunnea differs from most of its congeners, except T. aulopygia, T. intermedia and T. gyrina by having a wide mouth, width 54.0-59.7%HL (vs.39.0-53.3%HL).Additional characteristics for recognition of T. brunnea are diagnostic in combination: Nasal ossified with wide medial flanges partially sutured to lateral margin of mesethmoid; ribs 9-10; post-Weberian vertebrae 34-36.Additional features useful for distinguishing T. brunnea include details in coloration, such as: border of mouth whitish, contrasting with dark head; posterior border of nuchal shield usually whitish or pale; pectoral-fin spine usually with transverse bands; and caudal fin usually whitish with scattered dark brown blotches.
Description.Measured adult specimens 54.6-97.4mm SL; morphometric data presented in Table 4. Body deep, head depressed dorso-ventrally.Head robust, outline of head in dorsal view somewhat elliptic, broader than long.Trunk from dorsal-fin base to caudal peduncle gradually compressed laterally.Outline of head in dorsal view from snout tip to opercular margin slightly convex until pectoral-fin insertion.Ventral profile of head and abdomen slightly convex.Ventral profile of body gently curved, concave behind anal-fin origin.Head integument thin, cranial roof visible; well-developed adipose eye lid; eye latero-dorsally located in anterior portion of head; mouth terminal, upper lip extended posterolaterally as well-developed fleshy rictal fold; anterior nostril tubular, located on anterior border of snout, above lip; posterior nostril large, rounded, limited by small skin flap; transverse distance between anterior nostrils proportionally the same distance between posterior ones in HL.Maxillary barbel short, extending close to posterior tip of postcleithral process, sometimes larger; mental barbels short, tips not reach- Rostral border of cranium broad with mesethmoid as long as broad; premaxilla underneath with synchondral articulation; cranial fontanel elliptical, bounded by mesethmoid and frontal (Fig. 14); nasal ossified with narrow medial flanges, not sutured to mesethmoid in immature specimens, but sutured to mesethmoid in adults; autopalatine tubular, oriented obliquely to longitudinal axis of body; maxilla about same size of autopalatine; prevomer expanded anteriorly with well developed arrow-shaped lateral processes; jaws of equal size; premaxilla and dentary with three to four rows of conical teeth.First nuchal plate trapezoid; second nuchal plate slightly concave along lateral margins; third nuchal plate curved, projected laterally, with broad tip.Epioccipital process very small.Suspensorium, hyoid arch, branchial skeleton and opercular bones as in generic description.Suprapreopercle present as short canal bone.Five to six branchiostegal rays articu-lated with hyoid arch: three or four with anterior ceratohyal and two with posterior ceratohyal; last two flattened and expanded; basibranchial 2 forming osseous rod with broad cartilaginous anterior tip, separated from shorter basibranchial 3.

Color in alcohol.
Color pattern considered as diagnostic in original description by Mees (1974: 84): color dark brown in fresh specimens, with vague pale areas; older specimens with wavy longitudinal bands and dots of dark brown, alternating with pale brown areas; dorsal shield usually distinctly paler than body; pectoral, dorsal and adipose fins spotted with brown, dorsal fin largely dark brown; ventrals and anal fins hyaline, caudal fin hyaline with large irregular blackish brown dots.Contour of lips and anterior nostrils usually whitish.Pectoral fin usually with transversal dark bands.Live coloration in T. dunni aquarium specimen illustrated by Burgess (1989: pl. 113).
Large preserved specimens (over 90 mm SL) with diminished color pattern.These individuals bear spots, blotches or even stripes generally much less defined.
Color variation.Regional variation in pigmentation was observed in T. brunnea (as exemplified in Fig. 13).Suriname specimens attain smaller adult size (50-72 mm SL) and have irregular stripes or blotches along body (Fig. 13a).Specimens from Negro river attain larger size (60-97.4mm SL), and are mottled with dark and light brown areas (Fig. 13b).Some are completely dark brown along sides of body, with caudal-fin lobes irregularly striped (MZUSP 81139).
In the headwaters of upper Negro river, draining the Cerro de Neblina Mountains, the catfishes attain the largest size observed for the species, 116 mm SL, and have large irregular stripes on sides of body.A single population of T. brunnea was found in central Amazon, in the Trombetas river.These fishes have dark brown bands at the center of each caudal-fin lobe, a coloration pattern also observed in some specimens from the Negro river (INPA 15989).
Sexual dimorphism.Based on examination of gonads, T. brunnea attains sexual maturity above 54.6 mm SL.The upper Amazon population, however, is found to consist of larger individuals and maturation was attained above 70 mm SL.In mature females a genital papilla is not evident.The genital papilla of mature male is visible, with an emergent deferent duct.The anal fin of mature males (Fig. 15) is strongly modified, with three thickened unbranched rays.The first unbranched ray is the shortest ray, about three-quarter length of second unbranched ray.First unbranched ray is segmented,  Distribution.Tatia brunnea was described from the Suriname and Marowijne-Maroni river basins in Suriname.It was recorded in French Guiana from the Maroni and Sinnamary river basins.In Brazil it occurs in the Negro river drainage and at a single locality in Central Amazon basin, in the Trombetas river drainage (Fig. 6).

Remarks.
Until recently, T. brunnea was thought to be restricted to Suriname (Ferraris, 2003), although it was previously recorded in the Negro river as well (Wallace, 2002).The overall coloration of T. brunnea ressembles that of T. dunni, from upper Amazon.Details in coloration of caudal fin helps to distinguish between these two species, as in T. brunnea the caudal fin is whitish with dark spots or bands (vs.darker with whitish blotches in T. dunni).Additional distinctions include a wide head in T. brunnea, 86.6-93.4% HL (vs.narrow in T. dunni, 76.0-80.1% HL); a wide mouth, 54.0-59.7%HL (vs.narrow, 48.1-52.3%HL); and a male modified anal fin with sharply pointed distal tip (vs.short rounded distal tip).Tatia brunnea occurs in sympatry with T. intermedia in some rivers in Suriname and French Guiana and also in the Trombetas river.Head integument thick, cranial roof difficult to visualize; well-developed adipose eye lid; eye latero-dorsally located in anterior portion of head; mouth terminal, upper lip extended postero-laterally as well-developed fleshy rictal fold; snout margin rounded; anterior nostril tubular, located on anterior border of snout, above lip; posterior nostril thin, rounded, limited by small skin flap; transverse distance between anterior nostrils proportionally the same as distance between posterior ones.Maxillary barbel of moderate size, extending beyond posterior tip of postcleithral process, reaching vertical through origin or middle of dorsal fin; four mental barbels, tips not reaching pectoral-fin base, arranged in arc along ventral surface of jaw; inner mental barbel about 70.0-78.0%length of outer mentals.Postcleithral process well developed, almost reaching vertical through origin of dorsal fin.Caudal peduncle moderately deep, its depth about 11.0-13.0%SL.
Rostral border of cranium broad with mesethmoid broader than longer, premaxilla underneath with synchondral articulation; cranial fontanel elliptical, with single large opening, bounded by mesethmoid and frontal; nasal ossified, tubular, with no medial flanges (Fig. 17).Autopalatine tubular, oriented obliquely to longitudinal axis of body; maxilla about same size of autopalatine; prevomer expanded with a well developed arrow-shaped lateral processes; jaws of equal size; premaxilla and dentary with three rows of conical teeth.First nuchal plate short, pentagonal; second nuchal plate laterally concave; third nuchal plate projected laterally, with pronounced narrow tip.Epioccipital process small.Suspensorium, hyoid arch, branchial skeleton and opercular bones as in generic description.Suprapreopercle present as long canal bone.Six branchiostegal rays articulated with hyoid arch: four with anterior ceratohyal and two with posterior ceratohyal.Basibranchial 2 forming osseous rod with broad cartilaginous anterior tip, separated from shorter basibranchial 3.
Four infraorbital bones in incomplete series.Infraorbital 1 thin, with short ventro-lateral process around anterior border of eye; remaining infraorbitals thin, reduced to canalicular portions.Infraorbital 2 smallest, close to infraorbital 1, followed by non-ossified portion of canal below eye and by two posterior canal bones much close to sphenotic, forming rear of orbit.Lateral line on body with ossified canal bones only near head.Dorsal fin I,5; dorsal-fin spine with 15-17 antrorse serrations along entire anterior margin, posterior margin smooth.Pectoral fin I,5; pectoral-fin spine with 17-20 antrorse serrations along anterior margin; 14-15 retrorse serrations along posterior margin; serrations along both margins progressively larger towards spine tip.Pelvic-fin i,5, margin rounded.Adipose fin large, origin on vertical through middle anal-fin base.Anal fin iii, 7; anal-fin pterygiophores in 8 rod-like proximal radials and seven cartilaginous distal radials.Caudal fin forked, lobes with rounded tips, 8+9 principal rays, 5-8 upper procurrent, 5-6 lower procurrent rays.Caudal fin lobes about same length in both adult females and males.Nine pleural ribs attached to consecutive vertebrae.Post-Weberian vertebrae 32 (n=1).
Color in alcohol.Dorsal mid-line and latero-dorsal parts of body dark brown, with many small dark chromatophores, less concentrated over lips and chin.Head and nuchal shield dark.Ventrolateral parts of body pale, belly whitish.Dorsal-fin spine dark pigmented, subsequent rays grayish with dark base.Pectoral, pelvic, anal and adipose fins hyaline.Caudal fin dark brown, with dark chromatophores on fin rays.

Sexual dimorphism.
Based on observation of gonads, all examined T. caxiuanensis are adults.In females a genital papilla is not evident.The genital papilla of mature males is visible, with a skin tube around deferent duct.The anal fin of mature male is strongly modified with the second and third unbranched plus first branched rays elongated and thickened, Distribution.Known only from the type locality in Curuá river, lower Amazon basin, about 330 km southwest from the city of Belém, Pará, Brazil (Fig. 6).
Etymology.The specific name, caxiuanensis, is in reference to the Floresta Nacional de Caxiuanã, a preservation area where the catfishes were caught.
Remarks.Tatia caxiuanensis is one of the smallest Tatia, reaching maturity at 29.3 mm SL.Only T. gyrina reaches maturity at a smaller size (28 mm SL).Ferraris, 2003:476 [checklist].Ferraris, 2007: 77 [checklist].Color in alcohol.Coloration in preserved specimens umber, with rather long longitudinal pale grayish to whitish irregular blotches; dark markings form reticulations; under surface of head and abdomen whitish; fins with darker markings, more contrasted on caudal (Fowler, 1945b: 111).Dorsal surface of head almost dark brown; posterior part of nuchal shield faint, usually light brown.Contour of lips and anterior nostrils usually dark.Ventral part of head dark brown around chin barbels.Caudal fin dark with whitish spots over lobes.

Diagnosis
Color variation.Tatia dunni usually has faint irregular bands and spots over body.Some T. dunni, from the Peruvian Amazon, have a dark brown body and mottled anal fin (INHS 43890).Large specimens from the Purus river, in central Amazonia, usually have a completely dark body (INPA 17182) or a lightly spotted coloration (INPA 17184).
Sexual dimorphism.Based on examination of gonads, T. dunni attains sexual maturity above 70 mm SL.In mature females a genital papilla is not evident.The genital papilla of mature male is visible, with an emergent deferent duct.The anal fin of mature male (Fig. 21) is strongly modified, with three thickened unbranched rays.The first unbranched anal-fin ray has segments fused and is immediately preceded by a short tegumentary keel (Fig. 21, tk).The second unbranched ray has an intermediate size between the neighboring first and third rays.Third unbranched is the longest ray forming a short rounded tip (Fig. 21, uiii); distal segments smaller, antrorsely curved (Fig. 21, ac).First branched ray bearing retrorsely curved distal segments (Fig. 21, rc).Posterior branched rays are progressively shorter, with the last branched one somewhat reduced (Fig. 21, b6).
Hemal spines 15-18 interdigitate with anal-fin pterygiophores; with hemal spines 15-17 thickened in mature male, but are undifferentiated in females.The caudal-fin lobes have the same length in mature female, whereas upper lobe is slightly elongated in mature male.
Distribution.Tatia dunni has a wide distributional range, occurring in the upper Amazon, Ecuador and Colombia and the central Amazon, Brazil, in Solimões and Purus rivers.It is the species of Tatia that occurs at the highest elevations as it has been recorded at 1950 m abs, in Caquetá river drainage, Cauca mountains Morelia, Colombia (Fig. 6).
Remarks.Tatia dunni was placed in the synonymy T. intermedia by Mees (1974).The shared presence of white markings on dark body in both species was considered within the limits of intraspecific variation (Mees, 1974: 68).In spite of similarities in coloration, T. dunni is distinguished by its long preanal length, 70.0-75.0%SL (vs.65.0-69.4%SL in T. intermedia) and short interorbital distance, 54.1-59.4% HL (vs.60.1-63.6%HL in T. intermedia).The male modified anal fin differs in both species.In T. dunni the last branched ray is markedly reduced (vs.only slightly shorter than penultimate ray in T. intermedia).Gosline, 1945: 10 [in part, Apuré].Mago-Leccia, 1967: 225 [Venezuela].Burgess, 1989: 242, pl. 113, 114 [northeastern South America].Tatia galaxias Mees, 1974: 86-88, fig. 23 7. Body slim, head slightly depressed dorso-ventrally.Head large, robust, outline of head in dorsal view elliptic, broader than long.Dorsal outline of trunk from dorsal-fin base to caudal peduncle gradually compressed posteriorly.Lateral profile of head from snout tip to above opercular margin slightly convex to pectoral-fin insertion.Ventral profile of head and abdomen flat.Ventral profile of body concave posterior to anal fin.Head integument thin, cranial roof visible; well-developed adipose eye lid; eye latero-dorsally located in anterior portion of head; mouth terminal, upper lip extended posterolaterally as well-developed fleshy rictal fold; snout margin rounded; anterior nostril tubular, located on anterior border of snout; posterior nostril large, rounded, limited by small skin flap; transverse distance between anterior nostrils larger than distance between posterior ones.Maxillary barbel reaching vertical through end of dorsal-fin; mental barbel short, tips not reaching pectoral-fin base, arranged in arc along ventral surface of jaw; inner mental barbel about 50.0-67.0%length of outer mentals.Postcleithral process short, reaching vertical through origin of dorsal fin.Caudal peduncle deep, its depth about 14.2-18.3%SL.
Rostral border of cranium with mesethmoid as long as broad; premaxilla underneath with synchondral articulation; cranial fontanel elliptical, bounded by mesethmoid and frontal (Fig. 23); nasal ossified, with medial flanges sutured to lateral margin of mesethmoid; autopalatine tubular, oriented obliquely to longitudinal axis of body; maxilla small, shorter than autopalatine.Prevomer expanded anteriorly, with well developed arrow-shaped lateral processes, bearing small teeth attached to process in a large specimen with 85 mm SL (MCNG 25983).Jaws of equal size; premaxilla and dentary with two to three rows of conical teeth.First nuchal plate pentagonal; second nuchal plate broad, laterally concave; third nuchal plate projected laterally, with curved distal tip.Epioccipital process very small.Suspensorium, hyoid arch, branchial skeleton and opercular bones as in generic description.Suprapreopercle large.Six branchiostegal rays articulated with hyoid arch: four with anterior ceratohyal and two with posterior ceratohyal; last one largest and expanded.
Seven to eight infraorbital bones in usually complete series.Rarely incompletely ossified with 5 canal bones.Infraorbital 1 thin, with short ventro-lateral process limited to anterior border of eye; remaining infraorbitals thin, reduced to canalicular portions.Infraorbital 2-4 small, close to infraorbital 1. Infraorbitals 5-6 long ossified canals, bordering eye below and posteriorly.Last infraorbital much small, forming posterior orbital rim, in contact to sphenotic.Lateral line on body with ossified canal bones posteriorly to vertical through pelvic origin.

Color in alcohol.
Body usually dark brown with evenly spaced small white dots; chin with scattered pigment; underparts from chin to anus and ventrals unpigmented; pectoral fin pigmented lightly (Mees, 1974: 86).Dorsal fin with dark base and irregular spots; caudal fin usually with whitish spots irregularly distributed over lobes (Fig. 22).

Color variation.
Although the body usually is dark brown with whitish spots, T. galaxias may be polymorphic for color pattern, as a large array of variation regarding color is observed.Some specimens have a light brown body.Some have small roundish spots over the body and caudal fin, a common pattern in very young specimens < 40 mm SL.Some have caudal fin with dark tips.All distinct patterns may be found together in the same locality.
Sexual dimorphism.Based on examination of gonads, T. galaxias attains sexual maturity above 54.2 mm SL.In mature females a genital papilla is not evident.A genital papilla is visible in mature male, with a long slender emergent deferent duct (Fig. 24, dd).The male anal fin is strongly modified, with the anterior rays enlarged and thickened.The first unbranched anal-fin ray have segments fused and is preceded by a tegumentary keel (Fig. 24, tk).The second unbranched ray is elongated, with an intermediate size between the neighboring first and third rays.Third unbranched plus the first branched are the longest rays, forming a pointing tip.The third unbranched ray has the distal segments antrorsely curved (Fig. 24, ac).First and second branched rays have retrorsely curved distal segments (Fig. 24, rc).The remaining branched rays are progressively shorter, with the last ray not reduced (Fig. 24, b7).
Hemal spines 15-18 interdigitate with the anal-fin pterygiophores, being the hemal spines 15-17 thickened in mature males, but undifferentiated in females.The caudal-fin lobes have the same length in mature females, whereas in males the upper lobe is slightly elongated.
Distribution.Endemic to the Orinoco basin in Venezuela, including Meta drainage, in Colombia (Fig. 6).
Remarks.Mees (1974) described T. galaxias on the basis of its diagnostic color pattern of small white spots evenly spaced over a dark body (pattern exemplified in Fig. 22).Mees, (1974: 88) considered its coloration reminiscent of that of T. intermedia, except in T. galaxias the body is darker, the spots smaller, and the tail dark with white spots (vs.pale with dark spots and cross-bars in T. intermedia).We observed the dark body to be geographically variable in both T. galaxias and T. intermedia.In acidic black water rivers specimens of T. galaxias tend to have a darker body, when compared to those from clear water rivers.Together with the pattern of small white spots, other patterns of coloration were recognized among Orinoco specimens, such as uniformly dark and dark with white ellipsoid spots, the latter being rarest.In T. galaxias the spots are usually round, whereas in T. intermedia the spots are typically more ellipsoidal.Tatia galaxias also has a larger eye 37.0-42.9%HL (vs.21.4-26.3% in T. intermedia) and fewer ribs, 7, and fewer vertebrae 32-33 (vs. 10 ribs and 35-36 vertebrae in T. intermedia).
Rostral border of cranium thin with small mesethmoid, larger than long; premaxilla underneath with synchondral articulation; cranial fontanel large, rounded, bounded by mesethmoid and frontal (Fig. 2); nasal ossified as short tubular canal bone, lying between mesethmoid cornua and lateral ethmoid, not sutured to mesethmoid; autopalatine tubular, oriented obliquely to longitudinal axis of body; maxilla small, shorter than autopalatine; prevomer reduced, with short lateral process.Discrete prognathous mandibula; premaxilla and dentary with two to three rows of conical teeth.First nuchal plate trapezoid; second nuchal plate short; third nuchal plate short, with tips projected laterally.Epioccipital process very small.Suspensorium and opercular bones (Fig. 2); hyoid arch (Fig. 4) and branchial skeleton (Fig. 5) as in generic description.Suprapreopercle present as short canal bone.Five to seven slender branchiostegal rays articulated with hyoid arch: three to five with anterior ceratohyal and two with posterior ceratohyal; last one expanded.Basibranchial 2 forming osseous rod with broad cartilaginous anterior tip, separated from shorter basibranchial 3.

Color in alcohol. Illustration in
Species coloration described as follows (Fig. 25): Dorsal surface of head and dorsal fin dark brown; head irregularly striped in brown ventrally; sides of body mottled with numerous irregular spots; usually dark brown stripe along lateral line; body usually yellowish ventrally; pectoral-fin spine usually with transverse dark bands; adipose fin pale brown; caudal fin spotted with dark band on center of each lobe.Sands (1984: 40) illustrated a living specimen of T. gyrina.
Color variation.Variation in body pigmentation was observed between the Suriname and Amazonian populations.In Suriname specimens the body is usually yellowish ventrally or sometimes with a rounded brown spot present near each pelvic-fin base.No Amazon specimens had a rounded brown spot near the pelvic-fin base and the body is invariably yellowish ventrally.Variation in pectoral-fin spine pigmentation occur independent of geographical locality: pectoral-fin spine is usually transversely banded but is uniformly dark to unpigmented in some specimens.Coloration of the dark lateral stripe on the side of the body varies.In some Suriname specimens (ZMA 105.832) the dark brown lateral stripe has irregular dark and light areas.In addition, the lateral stripe was interrupted in some and absent in decolorized specimens.In Table 8.Morphometric data for Tatia gyrina.SD = standard deviation.
an upper Amazon specimen (FMNH 94752), the lateral stripe is light brown, not as dark as in the Amazon specimens.
Tatia gyrina occasionally occur together with T. strigata and in these situations the two species are remarkably similar in appearance.The situation is exacerbated by the fact that T. strigata taken with T. gyrina have a dark lateral stripe, a character otherwise rare in T. strigata.In these instances, the main way to distinguish the two species is by certain head measurements.Tatia gyrina has a deep (snout depth 50.0-59.4%HL), and broad head (head width 82.4-94.2%HL) and prognathous lower jaw; whereas T. strigata has a shallow (snout depth 41.3-47.3%HL) and narrow head (head width 70.1-76.7%HL), and jaws of equal sizes.There are also some minor color differences.The sides of body in T. gyrina are mottled, with variations in form and size of the individual spots, but never striated or striped like in T. strigata.Furthermore in T. strigata the stripes are long, almost horizontal and narrow.
Sexual dimorphism.Based on examination of gonads, T. gyrina attains sexual maturity above 28.0 mm SL.In mature females a genital papilla is evident, with the genital opening close to the anal-fin origin, emerging from a slender fleshy process.A female genital papilla is rare within Tatia.The genital papilla of mature male is evidenced by a swollen anal-fin base (Fig. 26).Dissection revealed the presence of a thick pouch inside it, formed by broad mass of some glandular tissue, with secretory material.A unique male deferent duct is present, externally elongate, thick and emergent (Fig. 26, dd).The extended deferent duct is also seen in young males, permitting the distinction between sexes even in juveniles.This condition is uniquely found in T. gyrina males.In other Tatia, as well as in most centromochlins, only short slender tip of deferent duct is externally visible, emerging from genital papilla.
The mature male modified anal fin (Fig. 26) is short, with a small tip, and three enlarged and thickened unbranched analfin rays.First unbranched ray with the segments fused or bearing a single median one in one specimen (CAS 36979), and is immediately preceded by a short tegumentary keel (Fig. 26, tk).The second and third unbranched rays are converging with first branched to form a short anal-fin tip (Fig. 26,uiii).No curved segments are associated with the anterior rays.The posterior branched rays are normally developed, with the last ray not reduced (Fig. 26, b7).
Hemal spines 13-16 interdigitate with the anal-fin pterygiophores, being the hemal spines 14-16 thickened in mature males, but undifferentiated in females.Minor sexual dimorphism is observed in male caudal fin: upper lobe of some males is slightly elongate, about 10% longer than lower one.The caudal-fin lobes have same length in mature females.
Distribution.Tatia gyrina occurs in the upper and central Amazon, in Peru, Colombia and Brazil.It is also found in rivers of northern Suriname (Fig. 6).
Remarks.This species was originally described by Eigenmann & Allen (1942) as Centromochlus gyrinus based on a single specimen from Iquitos, Peru.Nearly a decade latter, Boeseman (1953) described Centromochlus creutzbergi based on a specimen from Suriname, but without a comparison to Centromochlus gyrinus.Mees (1974) transferred both species to the genus Tatia, based on similarities in fin ray counts and the shape of adipose fin.For many years the Amazonian T. gyrina was known only from its holotype.The holotype of T. gyrina is old and has lost its color.The specimen, however, is a mature male, with a modified anal fin that is similar in appearance to the anal fin of specimens from Suriname identified as T. creutzbergi.Recent sampling of Amazon igarapés has made available more specimens, including adults, what has allowed for a more detailed morphological comparison of Amazon and Suriname populations.The new material indicates that T. creutzbergi from Suriname and T. gyrina from the Amazon are morphologically very similar and hereby considered conspecific under the older name T. gyrina.Differences generally associated with color pattern and certain head proportions are considered intraspecific geographic variation.Both have the same general coloration, a conspicuous dark lateral stripe and mottling on sides of body.In the Amazon populations, however, the dark stripe is interrupted in some specimens, whereas in all Suriname specimens examined the dark stripe is always present and conspicuous.In some Suriname specimens the pelvic-fin base has a characteristic darkened area, with paired brown spots.These markings are especially obvious in specimens recently captured.Some Suriname specimens have the ventral surface of body uniformly whitish, (ZMA 105.829), in the same way as Amazon specimens.The low number of vertebrae, 29 in Amazonian catfishes (n=3), and 30 in Suriname ones (n=6), was counted in some specimens only, and overlap of counts may occur.The Amazon and Suriname populations of T. gyrina also exhibit a few differences regarding head proportional measurements: head slightly broader and deeper in Amazon specimens, 88.8-94.2% and 56.3-59.4% HL, respectively (vs.narrower and shallower in Suriname, 82.4-86.7% and 50.0-55.4%HL, respectively); and mouth wider in Amazon specimens, 56.6-61.9%HL (vs.narrower in Suriname 40.2-45.6%HL).Regional differences in head measurements and vertebral counts are interpreted as intraspecific variation within T. gyrina.

Diagnosis.
Tatia intermedia is distinguished by the following combination of characteristics: wide elliptical cranial fontanel; short postcleithral process not reaching vertical through origin of dorsal fin; body coloration variable, usually with elliptical spots along sides of body, large specimens with faint spots; or color pattern uniformly pale brown; caudal fin with small spots or pale brown.The only other Tatia with a variable coloration is T. galaxias.Tatia intermedia differs from T. galaxias by its short postcleithral process (vs.long in T. galaxias); its small eye, 21.4-26.3%HL (vs.37.0-42.9% in T. galaxias) and its long snout 38.8-44.3%HL (vs.23.1-28.9% in T. galaxias).Additional features useful for distinguishing T. intermedia include: nasal ossified with wide medial flanges partially sutured to lateral margin of mesethmoid; caudal-fin lobes of mature females with same length, but mature males with elongated upper lobe.
Description.Measured specimens 50.4-91.2mm SL; morphometric data presented in Table 9. Body slim, head slightly depressed dorso-ventrally.Head large, robust, outline of head in dorsal view somewhat elliptial, broader than long.Trunk from dorsal-fin base to caudal peduncle becoming gradually compressed laterally.Lateral profile of head from snout tip to above opercular margin slightly convex until pectoral-fin insertion.Ventral profile of head and abdomen flat.Ventral profile of body gently curved, concave behind anal fin origin.
Head integument thin, cranial roof visible; well-developed adipose eye lid; eye latero-dorsally located in anterior portion of head; mouth terminal, upper lip extended posterolaterally as well-developed fleshy rictal fold; anterior nostril tubular, located on anterior border of snout; posterior nostril large, rounded, limited by small skin flap; transverse distance between anterior nostrils proportionally the same as distance between posterior ones.Maxillary barbel short, almost reaching vertical through origin of dorsal fin; mental barbel short, tips not reaching pectoral-fin base, arranged in arc along ventral surface of jaw; inner mental barbel about 55.0-65.0%length of outer mentals.Postcleithral process short, not reaching vertical through origin of dorsal fin.Caudal peduncle deep, depth about 13.9-18.1%SL.
Rostral border of cranium broad with large mesethmoid; premaxilla underneath with synchondral articulation; cranial fontanel large, elliptical, bounded by mesethmoid and frontal (Fig. 28); nasal ossified, with medial flanges sutured to lateral margin of mesethmoid; autopalatine tubular, oriented obliquely to longitudinal axis of body; maxilla small, shorter than autopalatine.Prevomer expanded anteriorly with well developed arrow-shaped lateral processes, bearing small teeth attached to process in examined large specimens (>74 mm SL).Jaws of equal size; premaxilla and dentary with three to four rows of conical teeth.First nuchal plate somewhat pentagonal; second nuchal plate concave along lateral margins; third nuchal plate curved, projected laterally.Epioccipital process very small.Suspensorium, hyoid arch, opercular bones and branchial skeleton as in generic description.Suprapreopercle present as short robust canal bone.Six branchiostegal rays articulated with hyoid arch: four with anterior ceratohyal and two with posterior ceratohyal; last one largest and laminar expanded.
Five infraorbital bones in incomplete series.Infraorbital 1 thin, with short ventro-lateral process on anterior border of eye; remaining infraorbitals thin, reduced to canalicular portions.Infraorbital 2 smallest, close to infraorbital 1, followed by non-ossified portion of canal below eye and three posterior ossicles bordering eye posteriorly: last one in contact to sphenotic.Lateral line on body with ossified canal bones posteriorly to vertical through pelvic fin origin.

Color in alcohol.
In the original description of Centromochlus intermedius, Steindachner (1877) did not mention the color pattern of the two syntypes.Steindachner (1881) noted a copper-colored body with regular spots and a silver gray caudal fin in specimens from Jutaí and Jutuarana, Amazon basin, when comparing those specimens with the syntypes.Only one decolorized syntype of C. intermedius (NMW 47355) was available for our examination.As the original color pattern for the syntypes was not clearly stated in species description, specimens from Marabitanos, the type locality, possibly were uniformly light brown.This is in agreement with the color pattern found in specimens from the Capim river, eastern Pará (Fig. 27a).Specimens from eastern Pará have the dorsal surface of the head and dorsal mid-line brown, the sides usually dark brown, the ventral contour of the head around the chin, lips and anterior nostrils brown, the body whitish ventrally, the dorsal fin with a dark base and irregular spots towards the fin tip, the pectoral, pelvic and adipose fins hyaline, and the caudal fin pale brown.
Color variation.Geographical and individual variation in coloration was observed throughout the distribution of T. intermedia.Besides the coloration in eastern Pará specimens (Fig. 27a), other patterns are found.In specimens from Amapá, Suriname and Guyana the common pattern is the presence of large light ellipsoid spots on dorsum and sides of body to caudal-fin tips; pale nuchal shield; and pectoral fin usually with transverse dark bands (Fig. 27b).
In the lower Amazon and upper Tocantins some specimens have a light brown body coloration and spotted caudal fin.In the upper Tocantins river drainage specimens usually have small light spots over the body becoming smaller towards the caudal-fin tip, a dark nuchal shield, and the pectoral fin usually light brown (Fig. 27c).Sometimes specimens with a spotted body and caudal fin co-occur with specimens having a uniformly light brown body and spotted caudal fin.In some localities specimens with light brown bodies may have the caudal fin spotted or plain light brown.
Differences in overall intensity of pigmentation were observed relative to size.In some very young specimens, less than 20 mm SL, the spots are vivid and sharply defined compared to some large specimens (up to 70 mm SL), wherein the spots are pale and poorly defined.The thick superficial skin layer obscures the coloration pattern in large T. intermedia, as is seen among other large sized Tatia.
Sexual dimorphism.Based on examination of gonads, T. intermedia attains sexual maturity above 50.4mm SL.In mature females a genital papilla is not evident.A thick genital papilla is visible in mature males, with a short deferent duct.The anal fin of mature male (Fig. 29) is strongly modified, with the anterior rays enlarged and thickened.The first unbranched ray have segments fused, immediately preceded by a large tegumentary keel (Fig. 29, tk).The second unbranched ray is elongated coalescing with the subsequent, third, ray.The third unbranched plus first branched are the longest rays, forming a pointed tip.The distal segments are antrorsely curved (Fig. 29, ac) on third unbranched ray.First and second branched rays with small retrorsely curved distal segments along outer margin (Fig. 29, rc).Posterior branched rays are progressively shorter, with the last ray not reduced (Fig. 29, b6).
Hemal spines 16-19 interdigitating with the anal-fin pterygiophores; being the hemal spines 17-19 thickened in mature males, but undifferentiated in females.Caudal-fin lobes with the same length in mature females; in mature males the upper lobe is more elongated.
Distribution.Originally described from the Amazon basin, T. intermedia is the most widely distributed member of the ge-  nus.It occurs in the upper reaches of the Araguaia, Tocantins, Xingu, and Capim rivers, tributaries of the lower Amazon of Brazil, northwards to the Suriname coastal rivers and the Essequibo river in Guyana (Fig. 6).
Remarks.Recognition of T. intermedia remained difficult for a long time.Mees (1974: Fig. 11) mistakenly associated the specimens from Suia Missu river in Mato Grosso, Brazil, as T. aulopygia.Mees' specimens were young, bearing small spots over the body, and their coloration conforms with that observed for other T. intermedia.Tatia intermedia and T. aulopygia are compared under the redescription of T. aulopygia.
The pectoral-fin spine with transverse bands was considered distinctive for T. intermedia by Soares-Porto (1998).Herein this feature is considered variable, as in some populations the spine is barred, some not.Soares-Porto (1998: 341) considered a barred spine as a derived feature shared between T. intermedia and T. brunnea, but such a condition varies intraspecifically in both species.Some large T. intermedia may be superficially similar to large T. dunni, as both species may have faint light spots on the sides of the body.In spite of this similarity, T. intermedia differs by having a short postcleithral process, not reaching the vertical through the dorsal-fin origin (vs.long, reaching vertical through dorsal-fin origin in T. dunni); a toothed prevomer in large specimens (vs.edentulous in large T. dunni); and a male modified anal fin with 3-5 elongate antrorse curved segments (vs.1-3 short antrorse curved segments in T. dunni).Diagnosis.Tatia meesi is uniquely distinguished from congeners by its coloration: dorsal surface of body, back and upper sides dark-brown sometimes with depigmented area around adipose fin.Cranial fontanel with two narrow openings: anterior one between mesethmoid and frontal and posterior one limited to frontal (Fig. 31).The fontanel apertures are separated from each other through an orbitosphenoid suture beneath frontal.The new species also is distinguished from congeners by a combination of characteristics: nasal ossified as tube, with narrow lateral flange not sutured to mesethmoid; pectoral fin I,4; caudal-fin lobes are the same length in both adult females and males.An additional feature useful for distinguishing T. meesi has the smaller adult size, less than 50 mm SL.
Description.Measured adult specimens 39.5-46.6 mm SL; morphometric data presented in Table 10.Body slim, head slightly depressed dorso-ventrally.Head robust, outline of head in dorsal view somewhat elliptic, broader than long.Trunk from dorsal-fin base to caudal peduncle becoming gradually compressed laterally.Lateral profile of head from snout tip to opercular margin slightly convex until pectoralfin insertion.Ventral profile of head and abdomen almost straight.Ventral profile of body gently curved, concave behind anal-fin origin.Head integument thin, cranial roof visible; well-developed adipose eye lid; eye latero-dorsally located in anterior portion of head; mouth terminal, upper lip extended postero-laterally as well-developed fleshy rictal fold; snout margin rounded, in dorsal view; anterior nostril tubular, located on anterior border of snout; posterior nostril large, rounded, limited by small skin flap; transverse distance between anterior nostrils proportionally same as distance between posterior ones.Maxillary barbel short, extending close to posterior tip of postcleithral process; mental barbel short, tips not reaching pectoral-fin base, arranged in arc along ventral surface of jaw; inner mental barbel about 51.0-64.0%length of outer mentals.Postcleithral process long almost reaching vertical through middle or end of dorsal fin.Caudal peduncle moderately deep, depth about 10.4-12.3SL.
Rostral border of cranium with mesethmoid approximately as long as broad; premaxilla underneath with synchondral articulation; elliptical cranial fontanel, with two narrow openings: anterior one between mesethmoid and frontal and posterior one limited to frontal.Fontanel apertures separated to each other by suture beneath frontal, along orbitosphenoid (Fig. 31).Nasal ossified, tubular, with narrow medial flanges, not sutured to mesethmoid; autopalatine tubular, oriented obliquely to longitudinal axis of body; maxilla about same size of autopalatine; prevomer expanded anteriorly , with well developed arrow-shaped lateral processes; jaws of equal size; premaxilla and dentary narrow with two or three rows of conical teeth.First nuchal plate very short, pentagonal; second nuchal plate slightly concave along lateral margins; third nuchal plate curved, projected laterally, with broad tip.Epioccipital process very small.Suspensorium, hyoid arch, branchial skeleton and opercular bones as in generic description.Suprapreopercle present as short canal bone.Five slender branchiostegal rays articulated with hyoid arch: three or four with anterior ceratohyal and two with posterior ceratohyal; last two flattened.Basibranchial 2 forming osseous rod with a broad cartilaginous anterior tip, separated from shorter basibranchial 3.
Color in alcohol.Dorsal surface of body, back and upper sides dark-brown sometimes with depigmented area around adipose fin.Lips and anterior nostril whitish.Head pigmentation pale, with posterior nuchal plates lighter.Lower sides and ventral surfaces whitish.Dorsal spine dark, subsequent rays darker only on its bases.Paired, anal and adipose fins unpigmented.Caudal-fin base with chromatophores becoming progressively more widely spaced, with hyaline lobes and tips.

Sexual dimorphism.
Based on examination of gonads, T. meesi attains sexual maturity above 39.5 mm SL.A genital papilla is not evident in females.The genital papilla of mature male is visible, with a short deferent duct.Adult male anal fin (Fig. 32) is strongly modified with a pointed tip.First unbranched anal-fin ray thickened.Second unbranched ray with a sharp tip curved towards the third unbranched ray, but not prolonged until the fin tip (Fig. 32, uii).Third unbranched ray is the longest one, forming a narrow fin tip, with distal segments gently curved (Fig. 32, uiii).First, second and third branched anal-fin rays are progressively shorter and curved towards the fin tip.Posterior branched rays normally developed; last ray not reduced (Fig. 32, b7).The caudal fin lobes have about same length in both adult males and females.
Distribution.Known only from type locality in the Essequibo basin, Guyana (Fig. 6).
Etymology.The specific name honors Dr. Gerloff F. Mees, for his significant contributions to our knowledge of the genus Tatia, especially with regards to the species of the Guyana shield.
Remarks.The Waratuk cataract, the type locality of T. meesi, consists of rapidly flowing water over huge boulders.At the base of the cataract is a large pool and backwater area with a substrate of sand, gravel and rubble over bedrock give shelter to some catfish species, including the tiny T. meesi (L.Page, pers.comm.).
Among Tatia, subdivided fontanel apertures, with two openings separated to each other by orbitosphenoid suture is observed only in T. meesi.Dissection of alcoholic specimens confirmed the presence of an anterior and posterior fontanel.The orbitosphenoid is the place for origin of the facial mandibular muscle adductor arcus palatini.Tatia meesi has some features that are uncommon within the genus such as a tubular nasal bone and caudal-fin lobes of equal size in both males and females.It shares with T. gyrina a low number of canalicular infraorbitals and a low number of branchiostegal rays.It is distinct from T. intermedia, the only congener in- habiting the Essequibo basin, due to a cranial fontanel with two openings (vs.single opening in T. intermedia); nasal tubular, rod-like, not sutured to mesethmoid (vs.with lateral bony flanges, sutured to mesethmoid in T. intermedia); adult specimens small sized, less than 50 mm SL (vs.large adult size, more than 50 mm SL).
The color pattern, consisting of small chromatophores concentrated mainly on dorsolateral part of body in T. meesi, resembles superficially the pattern in T. boemia.In T. meesi, however, the caudal fin is hyaline vs. with small spots in T. boemia.
Diagnosis.Tatia neivai is distinguished from other species of Tatia by its unique color pattern with scattered small white spots over the sides of the body and the caudal fin with dark vertical bars.The species is also distinguished by the following combination of characters: third nuchal plate broad, with short lateral projection, and post-Weberian vertebrae alternatingly ribbed and unribbed.Additional features useful for distinguishing the species include: caudal-fin lobes of equal length in mature females, upper lobe more elongated in mature males; 31-33 post-Weberian vertebrae.
Description.Measured adult specimens 48.Rostral border of cranium with mesethmoid as broad as long; premaxilla underneath with synchondral articulation; cranial fontanel narrow, elliptical, bounded by mesethmoid and frontal (Fig. 33); nasal ossified, with short medial flanges partially sutured to lateral margin of mesethmoid; autopalatine tubular, oriented obliquely to longitudinal axis of body; maxilla small, shorter than autopalatine; prevomer expanded anteriorly, with well developed arrow-shaped lateral processes; jaws of equal size; premaxilla and dentary with three to four rows of conical teeth.First nuchal plate short, somewhat elliptical; second nuchal plate laterally concave, partially in contact with supraoccipital in some specimens; third nuchal plate relatively straight, projected laterally.Epioccipital process small.Suspensorium, hyoid arch, branchial skeleton and opercular bones as in generic description.Suprapreopercle present as a very short canal bone.Six branchiostegal rays articulated with hyoid arch: four with anterior ceratohyal and two with posterior ceratohyal; last one largest and expanded.

Color in alcohol.
Color pattern usually with scattered small white spots over lateral sides of body mainly distributed over ventrolateral parts.Dorsal spine usually with transverse bands; pectoral-fin spine not pigmented.Caudal fin with irregular dark vertical bars.Posterior nuchal plates somewhat pale.Lips and nostrils whitish.Ventral portion of head around chin light brown.
Color variation.Regional variation in coloration was observed regarding specimens from the upper Paraná river immediately above the Sete Quedas waterfalls (MHNG 2355.92).These specimens have a dark body coloration, with only a few white spots ventrally, and a caudal fin with vertical bars.Some specimens from the upper Paraguay river in the Pantanal of Mato Grosso are light brown over dorsal parts of the body, with scatteredspots along ventrolateral parts of body, and with a vertically barred caudal fin.
Sexual dimorphism.Based on examination of gonads, T. neivai attains sexual maturity above 48.1 mm SL.A genital papilla is not evident in females.The genital papilla of mature male is visible, with a short deferent duct.Male anal fin (Fig. 35) is modified with the three unbranched and first branched rays enlarged and thickened.First unbranched ray is nonsegmented, and immediately preceded by a tegumentary keel (Fig. 35, tk).The second unbranched ray is elongated, coalescing towards fin tip.The third unbranched and first branched rays are the longest, forming a short fin tip.The third unbranched ray has two antrorsely curved distal segments (Fig. 35, al).The first branched ray has four or five retrorsely curved distal segments (Fig. 35, rl).The posterior branched rays become progressively shorter, with the last ray not reduced (Fig. 35, b7).
Hemal spines 14-17 are interdigitating with the anal-fin pterygiophores.The hemal spines 15-17 are thick in mature males, but undifferentiated in females.The male upper caudal-fin lobe is slightly elongate, about 15.0% longer than the lower lobe, whereas in mature females there are equal lobes.Remarks.Tatia neivai was observed in semi-lotic environments.Some of these catfishes were found hidden within marginal vegetation or were captured inside crevices of submersed trunks (O.Shibatta pers.comm.).
Tatia neivai was described based on a single specimen from the Piracicaba river.The holotype is lost, but Ihering (1930: pl. 13) illustrated the specimen as having irregularly scratched color pattern on the sides of the body and the caudal fin with dark vertical bars.This color pattern distinguishes T. neivai from most Tatia species, except some T. aulopygia.Variation in coloration may occur among populations, but the caudal fin is always barred, and sometimes resembles that of T. aulopygia.In spite of this similarity, T. neivai and T. aulopygia can be distinguished on the basis of proportional measurements, the size of cranial fontanel (bounded by mesethmoid and frontal in T. neivai vs. restricted to frontal in T. aulopygia); the modified anal fin of adult males (distal margin continuous, without notch in T. neivai vs. notched in T. aulopygia) and the post-Weberian vertebrae (31-33 in T. neivai vs. 38-39 in T. aulopygia).Diagnosis.Tatia nigra is uniquely distinguished from congeners by having dark brown body color (Fig. 36) and short postcleithral process about 60.0% HL (vs.more than 80.0% HL in other Tatia).Additional features useful for distinguishing T. nigra include: postcleithral spine not reaching vertical through origin of dorsal fin; nasal with well developed medial flanges; 32 vertebrae.Cranium with mesethmoid as long as broad; premaxilla underneath with synchondral articulation; elliptical narrow concavity for cranial fontanel, opening bounded by mesethmoid and frontal (Fig. 37); nasal ossified, with wide medial flanges partially sutured to lateral margin of mesethmoid; autopalatine tubular, oriented obliquely to longitudinal axis of body; maxilla about same size of autopalatine; prevomer expanded anteriorly with well developed arrowshaped lateral processes; jaws of equal size; premaxilla and dentary with three to four rows of conical teeth.First nuchal plate somewhat pentagonal; second nuchal plate concave along lateral margins; third nuchal plate curved, projected laterally, with small tip.Epioccipital process very small.Suspensorium, hyoid arch, branchial skeleton and opercular bones as in generic description.Suprapreopercle present as short canal bone.Six branchiostegal rays articulated with hyoid arch: four with anterior ceratohyal and two with posterior ceratohyal; last two flattened and expanded.Basibranchial 2 forming osseous rod with a broad cartilaginous anterior tip, separated from shorter basibranchial 3.
Color in alcohol.Tatia nigra dark colored in large adult specimens.Dorsal mid-line and dorsolateral parts of body dark brown, as well as dorsal surface of head, nuchal shield, dorsal fin and adipose fin (Fig. 36).Body progressively paler towards ventral parts.Ventral portion of head around chin, lips and anterior nostrils light brown.Belly whitish to origin of pelvic fin.Pectoral, pelvic and anal fins light brown.Caudal fin dark brown.
Sexual dimorphism.Tatia nigra attains sexual maturity above 80.0 mm SL.The mature females have a small intumescent genital papilla.Male genital papilla is formed by a thick skin flap around a slender emergent deferent duct.Male modified anal fin (Fig. 38) has three unbranched and first branched rays enlarged and thickened.The first unbranched anal-fin ray is immediately preceded by a tegumentary keel (Fig. 38,tk).The second unbranched ray has an intermediate size between the neighboring first and third rays.Third unbranched is the longest ray, slightly curved towards fin tip; bearing smaller antrorsely curved distal segments (Fig. 38, ac).First branched ray is slightly curved towards the fin tip.First and second branched rays have retrorsely curved distal segments (Fig. 38, rc).Posterior branched rays are progressively shorter; with the last ray not reduced (Fig. 38, b7).Caudal-fin lobes of both analyzed mature females and males have the upper lobe elongated.
Six mature males of T. nigra with a modified anal fin were examined.In two of these males the modified anal fin is laterally curved and spoon shaped (Fig. 39), suggesting reproductive modification for internal inseminating.
Distribution.Known from the central Amazon, in the Uatumã and Trombetas river drainages, northern tributaries of the Amazon river (Fig. 6).
Etymology.The specific name nigra, is a Latin reference to the dark color pattern of this species.Remarks.Tatia nigra has well-developed lateral ornamented medial flanges of bone on the nasal, but not as large as the flanges observed in T. aulopygia.The expanded nasal with medial flanges partially sutured to mesethmoid was recognized as a derived feature for the genus (Soares-Porto, 1998), and was also observed in T. aulopygia, T. boemia, T. dunni, T. neivai, T. strigata, and adult specimens of T. intermedia.
Female genital papilla in T. nigra is not a common condition within the genus.The only other Tatia with female genital papilla is T. gyrina.The intumescent female genital papilla may represent a transitory condition in species of Tatia, and perhaps is observed in specimens only close to reproductive phase.The elongated upper caudal-fin lobe in both mature females and males is rare within the genus and may be also associated to the reproductive phase.
Tatia nigra occurs in sympatry with T. brunnea in the Trombetas river, at lago do Batata, but not syntopically.The specimens of T. nigra were captured in the lake, while the T. brunnea was recorded from the igarapé Saracazinho, a tributary of the Batata lake.
Diagnosis.Tatia strigata is the only species of the genus with a completely striped color pattern, bearing whitish elongate longitudinal irregular stripes along lateral sides of body.
Color in alcohol.Dorsal surface, dorsal mid-line and lateral parts of body striated with light narrow longitudinal stripes.Dorsal surface of head and nuchal shield dark brown.Lips and anterior nostrils whitish.Ventral parts of head around chin whitish.Paired fins and anal fin hyaline.Adipose fin with dark base and hyaline tip.Caudal fin with dark brown rays and light brown membranes.Burgess (1989: pl. 113) illustrates live aquarium specimen.
Sexual dimorphism.A single adult male with modified anal fin was examined (MCZ 78092).Only young females are available, and genital papilla is not observed.A genital papilla is visible in the single mature male, with a thick skin flap around deferent duct.The anal fin of mature male (Fig. 42) is strongly modified, with three unbranched and the first two branched rays enlarged and thickened.The first unbranched ray has a rough anterior border and a curved tip (Fig. 42, ui).The second unbranched ray has the median segments enlarged anteriorly, projecting over the anterior ray (Fig. 42, uii); few segments are retrorsely curved (Fig. 42, rc).The third unbranched ray is the longest, forming a short tip (Fig. 42, uiii).The first and second branched anal-fin rays have retrorsely curved distal segments (Fig. 42, rc).The second and third branched rays are shorter, forming a central notch in the distal margin of the anal fin.Posterior branched rays are normally developed, forming a rounded posterior margin, about 20% more elongated than the anterior margin.The caudal-fin upper lobe is more elongated in mature males.Sexual dimorphism is not investigated as only young females are available.
Distribution.Tatia strigata is recorded from central Amazon basin, Negro river and Casiquiare Channel (Fig. 6).Tatia strigata is sympatric with T. dunni in the Casiquiare Channel and Negro river.
Remarks.Four branched pectoral-fin rays in T. strigata is not a common count within the genus.Species of Tatia with only four branched pectoral-fin rays are T. boemia, T. gyrina, T. meesi, some T. neivai and some T. intermedia.
A male anal fin with a notched distal margin is observed in both T. strigata and T. aulopygia, but the position of the notch is different.In T. strigata the notch is formed by reduc- tion of the second and third branched rays vs. reduction of fourth and fifth branched rays in T. aulopygia.The notched distal margin in male anal fin is not restricted to Tatia.Such a condition is also observed in Glanidium leopardus, with shortening of the fourth to sixth branched rays.

Fig. 6 .
Fig. 6.Drainage map of northern South America illustrating the geographic distribution of the species of Tatia.Symbols may represent more than one locality.Base map by Marilyn Weitzman.
ending in a rounded curved tip(Fig.18, uiii, b1).No tegumentary keel precedes the first unbranched anal-fin ray.The second unbranched ray is elongated, with an intermediate size between the neighboring first and third rays.The third unbranched and first branched rays are the longest (Fig.18, uiii, b1).The distal most segments of the third unbranched ray are antrorsely curved (Fig.18, ac).The second branched ray has a narrow tip.Posterior branched rays are progressively shorter and not reduced.
. 33-35 Tatia intermedia.Miranda Ribeiro, 1918: 734 [Piquete & Piracicaba, São Paulo].Fowler, 1951: 470 [literature compilation].Miranda Ribeiro compressed posteriorly.Lateral profile of head from snout tip to above opercular margin slightly convex until pectoral-fin insertion.Ventral profile of head and abdomen flat.Ventral profile of body concave posterior to anal fin.Head integument thin, cranial roof visible; well-developed adipose eye lid; eye latero-dorsally located in anterior portion of head; mouth terminal, upper lip extended posterolaterally as well-developed fleshy rictal fold; snout margin rounded; anterior nostril tubular, located on anterior border of snout; posterior nostril large, rounded, limited by small skin flap; transverse distance between anterior nostrils slightly larger than distance between posterior ones.Maxillary barbel moderate in size, extending to posterior tip of postcleithral process, sometimes longer; mental barbel arranged in arc along ventral surface of jaw, tips not reaching pectoral-fin base; inner mental barbel about 60.0-70.0%length of outer mentals.Postcleithral process well developed, almost reaching vertical through middle of dorsal fin.Caudal peduncle moderately deep, its depth about 13.6-14.8%SL.

Distribution.
Tatia neivai occurs in the upper Paraguay river, in the Pantanal of Mato Grosso, Brazil, upper Paraná river, and upper Paraíba do Sul river (Fig. 6).It is recorded from several tributaries of the upper Paraná river, Brazil, such as the Grande river in Minas Gerais, the Tietê and Paranapanema rivers in São Paulo, and the Tibagi river in Paraná.In the upper Paraíba do Sul river the species was recorded from Piquete, São Paulo State.The single record from the São Francisco river is uncertain (MZUSP 3801) because the locality data are dubious.

Table 2 .
Morphometric data for Tatia aulopygia.SD = standard deviation.Tatia aulopygia occurs in the Madeira river drainage of the Amazon basin.Most records are from upper reaches, in the Guaporé and Mamoré rivers (Fig.6).