A new genus of Neotropical rheophilic catfishes , with four new species ( Teleostei : Siluriformes : Pseudopimelodidae )

Rhyacoglanis, a new genus of the South American freshwater catfish family Pseudopimelodidae is described from cis-Andean portions of the continent. Rhyacoglanis is distinguished from other genera of the family by three synapomorphies: presence of a light blotch on the cheek; a connection between the middle of the dark caudal-fin stripe and the dark caudal-peduncle pigmentation; and 30-35 total vertebrae. Species of Rhyacoglanis are rheophilic and strongly associated with rapids and other swift-flowing waters. A phylogenetic analysis based on 41 morphological characters yields a hypothesis of monophyly of the Pseudopimelodidae and Rhyacoglanis. Pimelodus pulcher Boulenger, 1887, from the western Amazon basin is designated as type-species of the new genus and redescribed. Four new species are described: Rhyacoglanis annulatus, from the río Orinoco basin, with a nearly ringed dark band on the caudal peduncle, and a larger distance between anus and anal-fin origin; R. epiblepsis, from the rio Madeira basin, with numerous dark spots scattered on the body, and rounded caudal-fin lobes; R. paranensis, from the upper rio Paraná basin, with three distinct dark bands on the body, and 31-33 total vertebrae; and R. seminiger, from the rio Juruena basin, with subdorsal and subadipose dark bands fused anteroposteriorly, and a separate dark band on the caudal peduncle.

Pseudopimelodids are readily recognized by the combination of small skin-covered eyes, short maxillary and mental barbels, a wide mouth, relatively small heads, stout, serrate dorsal-and pectoral-fin spines and, in particular, various patterns of dark body blotches 2 e160132[2] (Shibatta, 1998).Lundberg et al. (1991a) corroborated pseudopimelodid monophyly with five synapomorphies: 1) absence of a spike-like wing of the lateral ethmoid membrane bone projecting beyond the palatine condyle; 2) foreshortened metapterygoid at least twice as broad than long with minimally its dorsal fourth or more deflected medially and usually subtended by a ridge or crest; 3) broad entopterygoid with a sharp anterolateral process and wide comma-shaped ectopterygoid, both bones moveably attached to the neurocranium between the lateral ethmoid-orbitosphenoid suture and the palatine; 4) broad third to seventh (last) proximal dorsal-fin radials in contact for their entire lengths (in genera of moderate to large body sizes) or narrowly separated (in the small sized Microglanis); and 5) absence of the dorsal hypohyal.
Numerous authors have discussed the validity of Pimelodus (Pseudopimelodus) pulcher, which Boulenger (1887) described originally from Ecuador.Eigenmann (1890) recognized it as Pseudopimelodus pulcher.Miranda-Ribeiro (1914) described a species from the rio Paraguay basin of southeastern Brazil with a coloration similar to that of P. pulcher as Pseudopimelodus variolosus.Mees (1974) considered P. pulcher and P. variolosus to be junior synonyms of P. zungaro zungaro; a hypothesis rejected by later authors (e.g., Shibatta, 2003a), who recognized P. pulcher as valid with P. variolosus as a junior synonym.
Analysis of Pseudopimelodus samples from various cis-Andean locations demonstrated that P. pulcher is a species complex, most members of which are undescribed.These form a clade broadly ranging across the Amazon basin and portions of the rio Paraná and the río Orinoco drainages.We explore the variation in what was considered P. pulcher, redescribe that species, diagnose a new genus, describe four new species of this new genus, and advance a hypothesis of its monophyly and internal relationships.

Material and Methods
Morphometrics.Twenty-nine point-to-point measurements were taken to 0.1 mm with dial calipers on the left when possible (Fig. 1).These are: Anus to anal-fin distance; Adipose-fin base length; Anal-fin base length; Anterior to posterior nostril distance; Body depth; Caudal peduncle depth; Caudal peduncle length; Dorsal-fin base length; Distance between the dorsal and pelvic fins; Distance between pelvic fins; Distance from pelvic fin to anus; Distance between posterior nostrils; Dorsal-fin spine length; Head depth; Head length (HL); Interorbital distance; Length of postcleithral process; Maxillary barbel length; Mouth width; Orbital diameter; Pelvic-to anal-fin distance; Predorsal distance; Pectoral girdle width; Pelvicfin length; Posterior nostril to orbit distance; Prepelvic length; Pectoral-fin spine length; Snout length; Standard length (SL).

Morphometric analysis.
Measurements are presented as percentages of SL, except for the subunits of the head, which are presented as percentages of HL.Percents of HL are presented as integer values, because of the higher measurement error.
Principal Component Analysis (PCA) was performed with log transformed morphometric variables using PAST (Hammer et al., 2001).The first component‚ which always encompasses the greatest variation is interpreted as representative of size when all original variables are significantly positively correlated with the axis, and the other components, with both positive and negative variables, are decreasing representatives of shape (Jolicoeur, Mosimann, 1960;Neff, Marcus, 1980).The characters contributing most to each axis were identified by examining the eigenvalue loadings.
Counts.Counts were made on the left side of the body when possible.Counts of dorsal-, pectoral-, pelvic-, analand principal and procurrent caudal-fin rays, gill rakers, ribs, branchiostegal rays and vertebrae were taken from X-radiographs of alcohol-preserved specimens and from cleared and stained (c&s) specimens.Gill-raker counts of the first gill arch are given for epibranchial and ceratobranchial bones.Total vertebrae include the free vertebrae plus the five united vertebrae of the Weberian apparatus.The compound caudal centrum (PU1 + U1) is counted as a single element.Frequencies of counts are presented in parentheses, with the holotype value indicated by an asterisk.Phylogenetic analysis.In addition to the five species treated herein, one representative species of each genus of the Pseudopimelodidae was included in a parsimony analysis of morphological chraracters.Analysis also included one member each of Pimelodidae (Steindachneridion scriptum) and Heptapteridae (Rhamdia quelen), families hypothesized to be closely related to the Pseudopimelodidae (Sullivan et al., 2013).The analysis was performed using TNT (Goloboff et al., 2008) with implicit weight and traditional search (TBR option), and using Ictalurus punctatus as the outgroup and for tree rooting.Multistate characters were treated as unordered because of lack of prior knowledge about character development and polarity.RI and CI were calculated using the macro script "statsall.run"V. 1.3 developed by Peterson L. Lopes (Universidade de São Paulo), available at Google groups "TNT-Tree Analysis using New Technology > Per character CI and RI".The list of synapomorphies includes only the non-ambiguous synapomoprphies.

Diagnosis.
Rhyacoglanis is distinguished in the Pseudopimelodidae by three characters, the first two of which autapomorphic: 1) the dorsal and lateral surfaces of the head are grey with a light blotch on the cheek (vs.completely grey in Cruciglanis and Pseudopimelodus, black in Batrochoglanis and Microglanis and ligth in Cephalosilurus and Lophiosilurus); 2) the dark stripe along the midline of the upper and lower caudal-fin lobes is confluent with a dark caudal peduncle blotch (vs.dark stripes on caudal fin not confluent with dark caudal-peduncle pigmentation or absent altogether); 3) 30-35 total vertebrae (vs. 36-44).Rhyacoglanis differs from other pseudopimelodids except Cruciglanis and Pseudopimelodus by the combination of the presence of the vomer, the anterior nostril located slightly posterior of the rictus nearly at the vertical through the posterior of the base of the maxillary barbel, and the thick skin on the pectoral-fin spine.Rhyacoglanis differs from Cruciglanis and Pseudopimelodus in the number of total vertebrae (31)(32)(33)(34)(35)(41)(42).It differs from Pseudopimelodus in the long posterior cleithral process almost reaching the vertical through the dorsal-fin origin (vs.very short process falling short of that vertical).Rhyacoglanis is distinguished from Cruciglanis by the lack of lateral processes on the second basibranchial (vs.presence of these processes resulting in a cross-shaped ossification) and a pelvic-fin origin at the vertical through the terminus of the dorsal-fin base (vs.slightly posterior of that point).Additional diagnostic characters for Rhyacoglanis in the Pseudopimelodidae are the small maximum body size (less than 100 mm SL vs. more than 100 mm SL in Cephalosilurus, Lophiosilurus and Pseudopimelodus); the rounded anterior head outline in dorsal view (vs.an almost trapezoidal head in Lophiosilurus); the terminal mouth opening forward (vs.superior mouth in Lophiosilurus or supraterminal in Cephalosilurus, and Pseudopimelodus); the very wide frontal fontanel (vs. a narrow fontanel in Cruciglanis and Pseudopimelodus); the thin, elongate, arched mesocoracoid in ventral view (vs.triangular in Pseudopimelodus); a posterolaterally projected dentigerous premaxillary plate (vs.projection absent in Microglanis); the laterally expanded anterior transverse process of the fourth vertebrae (vs.unexpanded process in Batrochoglanis, Cephalosilurus, Lophiosilurus and Microglanis); the forked caudal fin with pointed or rounded lobes and a lower lobe usually longer than the upper lobe (vs.an emarginate caudal with the upper lobe longer than the lower lobe in Batrochoglanis and Microglanis, or a round caudal-fin margin in Cephalosilurus and Lophiosilurus); the elongate caudal peduncle (vs. a short peduncle in Batrochoglanis); the adult pigmentation pattern of two or three well-defined dark body bands (vs.bands absent at least at some point in ontogeny in Cephalosilurus and Lophiosilurus); and the e160132 [5] head pigmentation slightly darker than the ground body coloration (vs. the similar head and body pigmentation in Cephalosilurus and Lophiosilurus).

Key to species of Rhyacoglanis
Description.Body proportions presented in Tab. 1. Body depressed from snout tip to dorsal-fin origin; progressively posteriorly compressed from that point to caudal-fin base.Dorsal profile of posterodorsal portion of head and body nearly straight to dorsal-fin origin; dorsal-fin base inclined slightly posteroventrally and nearly straight; region between posterior terminus of dorsal-fin base and adipose-fin origin nearly straight.Ventral profile of head and body nearly straight from lower jaw margin to posterior of anal-fin base.Caudal peduncle profile slightly concave along dorsal and ventral margins.
Head depressed; slightly longer than wide.Anterior margin convex in dorsal view.Head with well developed unculiferous tubercles primarily dorsally.Mouth terminal and wide; width more than one-half of HL.Upper jaw slightly longer than lower jaw.Lips thick; most developed on lateral surface of lower jaw and proximate to rictus.Premaxillary tooth plate posterolaterally pointed.Anterior nostril located immediately posterior to vertical through rictus.Eye small, superior, covered by skin, slightly posterior of anterior one-third of HL.Opercular membrane well developed; margin reaching pectoral-fin origin.Maxillary barbel base enlarged.Tip of adpressed barbel reaching pectoral-fin origin.Tip of adpressed inner mental barbel extending slightly beyond base of outer mental barbel, but falling short of barbel tip.Tip of adpressed outer mental barbel reaching pectoralfin origin.Dorsal fin trapezoidal overall; distal margin rounded; length of longest ray equal to fin-base length.Dorsal-fin origin immediately posterior to anterior one-third of body and anterior to one-half of SL.Tip of adpressed dorsal fin reaching midpoint between dorsal and adipose-fin bases.First dorsal-fin ray (spinelet) small, rigid, and forming dorsal-fin spine-locking mechanism.Second ray a spine with anterior margin smooth and posterior margin with retrorse serrations.Dorsal-fin rays I,6*(2).Adipose fin long; its base longer than that of dorsal fin; posterior margin free and slightly angular.Pectoral fin slightly triangular overall with posterior margin rounded.Tip of adpressed pectoral fin reaching vertical through middle of dorsal-fin base.First pectoral-fin ray strong, rigid and developed as spine with similar size serrae along anterior and posterior margins.Serrations on posterior margin retrorse.Tip of bony pectoralfin spine notched (Fig. 3a).Pectoral-fin rays I,6* rays (2).Pelvic fin almost triangular with posterior margin rounded.Pelvic-fin origin at vertical through base of penultimate dorsal-fin ray.Tip of adpressed pelvic fin falling short of anal fin but extending beyond vertical through adiposefin origin.Pelvic-fin rays i,5*(2).Anal fin margin rounded distally; base shorter than that of adipose-fin.Anal-fin rays iii,7*(2).Caudal fin forked with pointed lobes; ventral lobe slightly longer than dorsal lobe.Principal caudal-fin rays i,6,8,i*(2).Dorsal procurrent rays 12(1) or 14*(1); ventral procurrent rays 9(1) or 10*(1).
Posterior cleithral process well developed, pointed, reaching vertical through dorsal-fin origin.Axillary pore present.Lateral line complete.Total vertebrae 34(1) or 35*(1).Ribs 9*(2).Gill rakers 1,1,4*(1) or 1,1,5(1).Color in alcohol.Ground color light brown.Head with dark spots dorsally, on operculum, and ventral to orbit.Region over adductor mandibulae muscle lightly colored.Two small dark spots posterodorsally on head.Subdorsal band narrow, somewhat triangular.Subadipose band nearly rectangular.Region between bands with scattered small, irregularly shaped, dark spots.Caudal-peduncle band irregularly shaped; central region unpigmented.Dorsal fin dark on basal two-thirds and unpigmented posteriorly and distally.Adipose fin with dark pigmentation anteriorly, anterobasally and centrally.Caudal fin hyaline overall with thin arched dark band transversing each lobe; overall pattern resembling sideways V; distal region lightly colored.Anal fin hyaline other than dark blotch near base and series of dark spots aligned across middle of rays.Pectoral and pelvic fins hyaline overall; each crossed by dark stripe.
Geographical distribution.Rhyacoglanis annulatus is known solely from the southern portions of the río Orinoco basin in Venezuela (Fig. 4).
Etymology.The specific name, annulatus, is a Latin adjective meaning ringed, in reference to the caudalpeduncle band with a light inner region.
Conservation status.Only two specimens of R. annulatus are known, representing two localities.This rarity in collections suggests that the species may be rare in nature as well.The geographic distribution of R. annulatus in the upper río Orinoco basin must be wide, as the localities cover a broad geographic region with up to 40,000 km 2 .However, in light of extent of occurrence superior to 20,000 km 2 , and lack of evidence indicating population decline or fluctuations, R. annulatus should be assigned a Least Concern (LC) IUCN (2016) status.
Remarks.Rhyacoglanis annulatus is known from two preserved specimens collected in widely separated areas.An internet site (Fluvial, by Oliver Lucanus) (http://www.fluvalaquatics.com/ca/explore/expeditions/metaexpedition/#.VP3nn_nF-FU), shows a third specimen identified as Pseudopimelodus cf.raninus which is rather R. annulatus as evidenced by the unique caudal-peduncle pigmentation.This specimen from the río Meta represents a distinctly more northwesterly record for the species in the río Orinoco system.
Rhyacoglanis epiblepsis differs from R. paranensis by the intensely spotted lateral surface of body (vs.presence of only a few dark spots).Rhyacoglanis epiblepsis is differentiated from R. seminiger by the distinct separation of the dark subdorsal and subadipose bands (vs.fusion of those bands) and well developed serrations along the entire anterior pectoral-spine margin (vs.weak serrations limited to the basal portion of the margin).Rhyacoglanis epiblepsis differs from R. pulcher in the possession of numerous dark spots on the body (vs.limited spots) and lower number of total vertebrae (31-33 vs. 34-35).
Description.Body proportions are presented in Tab. 2. Body depressed from snout tip to dorsal-fin origin; progressively more compressed from that point to caudal-fin base.Dorsal profile of head and body posterodorsally nearly straight from snout tip to dorsal-fin origin.Dorsal-fin base slightly straight; profile nearly straight from limit of dorsal-fin base to adipose-fin origin.Ventral profile of head and body very slightly convex from margin of lower jaw to end of anal-fin base.Caudal peduncle concave dorsally and ventrally.Head depressed, slightly longer than wide.Anterior margin very slightly convex in dorsal view.Head with unculiferous tubercles mainly dorsally.Mouth terminal, wide, more than one-half of HL.Upper jaw slightly longer than lower jaw.Lips thick, well developed primarily on lateral surface of jaws.Premaxillary tooth plate with posteriorly pointed projection.Anterior nostril immediately posterior of vertical through rictus.Eye small, superior, Dorsal fin trapezoidal; distal margin rounded; length of longest ray shorter than fin base.Dorsal-fin origin immediately posterior to anterior one-third of body length and anterior to one-half of SL.Tip of adpressed dorsal fin falling short of midpoint between bases of dorsal and adipose fins.First dorsal-fin ray (spinelet) small, rigid, and forming dorsal-fin locking-mechanism.Second ray a spine with anterior margin smooth and posterior margin bearing retrorse serrations.Dorsal-fin rays I,6* rays (15).Adipose fin long; base longer than that of all other fins; posterior extremity free and rounded.Pectoral fin slightly triangular overall with distal margin rounded.Tip of adpressed pectoral fin falling short of pelvic-fin origin.First pectoral-fin ray strong, rigid, and forming spine with retrorse serrations along anterior and posterior margins.Serrations of posterior margin slightly larger, more so distally (Fig. 3b).Pectoralfin rays I,6* (15).Pelvic fin almost triangular with distal margin rounded.Pelvic-fin origin at vertical through base of penultimate dorsal-fin ray.Tip of adpressed pelvic fin falling short of anal-fin origin and of vertical through adipose-fin origin.Pelvic-fin rays i,5*(15).Anal fin rounded distally.Anal-fin rays iii,5(2), iv,5(5), iii,6(7), iv,6*(6), iii,7(2).Caudal fin forked with rounded lobes; lower lobe slightly longer than upper lobe.Principal caudal-fin rays i,6,7,i(2), i,6,8,i*(18), i,7,8,i(5).
Color in alcohol.Ground color brown.Head with dark spots dorsally, on opercle, and ventral to orbit.Region over adductor mandibulae muscle lightly colored in many specimens.Lateral and dorsolateral surface of body covered by small dark spots.Subdorsal band nearly triangular; subadipose band trapezoidal; caudal-peduncle band with straight anterior and biconcave posterior margins.Dorsal fin with dark stripes basally and across midsection with lightly colored stripes along distal margin and ventral one-third of posterior five rays.Adipose fin with central portion entirely dark brown.Caudal-fin ground coloration light; each lobe with posteriorly arching dark band and lobe margins lightly pigmented.Pectoral, pelvic and anal fins with thin, incomplete, dark stripes.Completely spotted individuals with spots extending onto fins (Fig. 6).
Etymology.The specific name, epiblepsis, is an adjective from the Greek epi (= up), and blepsis (= act of sight) in reference to the dorsal position of the eyes.
Conservation status.Several specimens of R. epiblepsis were collected, potentially indicating that the species is locally common.However, because R. epiblepsis, is known only from the type locality, is it not possible to estimate its actual distribution.Considering the absence of information about its distribution and population dynamics, R. epiblepsis should be assigned a Data Deficient (DD) IUCN ( 2016) status.Head depressed; wider than long.Anterior outline of head convex in dorsal view.Head with undeveloped unculiferous tubercles laterally and dorsally.Mouth terminal, wide; width greater than one-half HL.Upper jaw slightly longer than, or same length as, lower jaw.Lips thick, well developed mainly close to rictus.Premaxillary tooth plate posterolaterally pointed.Anterior nostril located immediately posterior to vertical through rictus.Eye small, superior, covered by skin, slightly posterior to anterior one-third of HL.Opercular membrane well developed; margin reaching pectoral-fin origin.Maxillary-barbel base enlarged.Tip of adpresssed barbel reaching pectoral-fin origin.Adpressed inner mental barbel extending posteriorly slightly beyond outer mental-barbel base but falling short of barbel tip.Tip of adpressed outer mental barbel reaching margin of opercular membrane but falling short of pectoralfin origin.
Color in alcohol and in life.Ground color light brown in alcohol; light orange in life (Fig. 8).Head with dark spots on dorsal surface, opercle, and region ventral to orbit.Region over adductor mandibulae muscle lightly colored.Iris dark in alcohol; light gray in life.Dark subdorsal band with irregular anterior and posterior margins; extending to ventral region of body but not contacting contralateral counterpart.Subadipose band with irregular anterior and nearly straight posterior margins.Lightly colored region between subdorsal and subadipose bands with scattered dark spots.Anterior margin of caudal-peduncle band nearly straight and posterior margin in shape of shallow, posteriorly open sideways V. Dorsal fin with dark pigmentation covering fin other than for distal one-fifth.Adipose fin with dark blotch centrally.Anal fin with dark basal spot and dark stripe on midsection; two regions conjoined posteriorly.Caudal fin hyaline basally with broad dark band across each lobe and lobe tips largely hyaline.Pectoral and pelvic fins hyaline except for transverse dark stripe on each.
Geographical distribution.Rhyacoglanis paranensis is only known from the upper rio Paraná basin in Brazil (Fig. 4).
Etymology.The specific name, paranensis, is an adjective in reference to the occurrence of the species in the upper rio Paraná basin.
Conservation status.Several specimens of R. paranensis were obtained from collections, suggesting that the species is not rare.Furthermore, the geographic distribution of R. paranensis in the upper rio Paraná basin must be wide, as the localities cover a broad geographic region of approximately 500,000 km 2 .The construction of several hydroelectric power plants along the upper rio Paraná will likely fragment the species distribution by destroying the preferred habitat in rapids, and represents a potential threat to R. paranensis.However, in light of the extent of occurrence exceeding 20,000 km 2 , and lack of evidence indicating population decline or fluctuation, we recommend assigning R. paranensis an IUCN (2016) conservation status of Least Concern (LC).(Boulenger, 1887)   Description.Body proportions are given in Tab. 4. Body depressed from snout tip to dorsal-fin origin; progressively compressed from that point to caudal-fin base.Dorsal profile of head and body posterodorsally nearly straight from snout tip to dorsal-fin origin; dorsal-fin base slightly straight; profile nearly straight from terminus of dorsal-fin base to adipose-fin origin.Ventral head and body profile slightly convex to almost straight from lower jaw margin to posterior limit of anal-fin base.Caudal peduncle profile slightly concave along dorsal and ventral margins.Head depressed; slightly longer than wide.Anterior margin convex in dorsal view.Head with weakly developed scattered unculiferous tubercles laterally and dorsally.Mouth terminal and wide; width more than one-half of HL.Upper jaw slightly longer than, or same length as, lower jaw.Lips thick and well developed, more so proximate to rictus.Premaxillary tooth plate posterolaterally pointed.Anterior nostril immediately posterior to vertical through rictus.Eye small, superior, covered by skin, slightly posterior to anterior one-third of HL.Opercular membrane well developed; margin falling short of pectoral-fin origin.Maxillary barbel base enlarged.Tip of adpressed maxillary barbel falling short of opercular margin.Tip of adpressed inner mental barbel surpassing base of outer mental barbel but falling short of tip of that barbel.Tip of adpressed outer mental barbel reaching opercular membrane margin.

Rhyacoglanis pulcher
Dorsal-fin trapezoidal with distal margin rounded and first branched ray longer than dorsal-fin base.Dorsal-fin origin immediately posterior to anterior one-third of body but anterior to one-half of SL.Tip of adpressed dorsal fin reaching slightly beyond midpoint between dorsal-fin base terminus and adipose-fin origin.First dorsal-fin ray (spinelet) small, rigid and forming dorsal-fin spine-locking mechanism.Second ray in form of spine with anterior margin smooth and posterior margin bearing retrorse serrations.Dorsal-fin rays I,6(3).Adipose fin long; base longer than that of other fins; posterior margin free and rounded.Pectoral-fin margin somewhat triangular overall with posterior margin rounded.Tip of adpressed pectoral fin falling short of pelvic-fin origin.First pectoral-fin ray strong, rigid and in form of spine with serrae along anterior and posterior margins; posterior serrations retrorse and distinctly larger than anterior serrae; pectoral-fin spine notched distally (Fig. 3d).Pectoral-fin rays I,5(1) or I,6(2).Pelvic-fin profile almost triangular; posterior margin rounded.Pelvic-fin origin immediately posterior to vertical through terminus of dorsal-fin base.Tip of adpressed pelvic fin reaching vertical through adiposefin origin.Pelvic-fin rays i,5(3).Anal-fin margin rounded; base shorter than that of adipose fin.Anal-fin rays iii,7(2) or iv,6(1).Caudal fin forked; lobes pointed; ventral lobe slightly longer than, or almost same length as, dorsal lobe.Caudal-fin principal rays i,6,8,i.Dorsal procurrent rays 17(2) or 18(1); ventral procurrent rays 15(1), 16(1), or 17(1).
Color in alcohol.Pigmentation faded in examined specimens.Ground color light brown.Head with dark spots dorsally and ventral to eye.Body with dark subdorsal, subadipose and caudal-peduncle bands.Subdorsal band somewhat triangular, ventrally narrower and extending to ventral region of body with dorsal and ventral extensions continuous with subadipose band.Subadipose band overall rectangular with dorsal and ventral anterior and posterior extensions continuous with similar extensions of subdorsal and caudal-peduncle bands.Caudalpeduncle band with anterior margins extending along border forming a distinct anteriorly directed sideways V. Dorsal fin covered by dark band other than along distal one-fifth.Adipose fin with large dark central spot.Anal fin with two dark transverse stripes.Caudal fin hyaline other than for arched dark distal band on each lobe; bands of each lobe confluent on middle caudal-fin rays; dark pigmentation continuing anteriorly to caudal peduncle band; overall dark pigmentation in form of posteriorly directed sideways Y. Pectoral fin hyaline other than for transverse dark stripe slightly posterior to middle of fin.Pelvic fin with curved dark transverse stripe near midlength (Figs.9-10).

Geographical distribution.
Rhyacoglanis pulcher occurs in the Ecuadorian Amazon (Fig. 4).Though Mees (1974) indicated that R. pulcher also occurs in the río Popoi in the upper río Beni in Bolivia, the río Marañón in Peru, and at Sangadina, Mato Grosso, Brazil, we were unable to examine and confirm the identification of the specimens from the two last localities and the latter in particular represents a questionably unusually great range extension.The río Beni specimens reported on by Mees (1974) are rather R. epiblepsis, described herein.
Conservation status.Few specimens of R. pulcher were obtained from collections, suggesting that the species may be naturally rare.However there is a possibility that R. pulcher has a wider distribution in the rio Amazonas basin.In the absence of the information about geographic distribution and population dynamics necessary to properly evaluate the extent of occurrence, we recommend assigning an IUCN (2016) status of Data Deficient (DD) to R. pulcher.

Remarks.
After nearly 150 years of preservation, the syntypes of Pseudopimelodus pulcher are very soft with faded coloration.However, the residual pigmentation in these specimens agrees closely with the illustration presented by Boulenger (1887), suggesting that the drawing can be taken as an accurate depiction of the original pigmentation.Most features were accurately described in the original description.Boulenger commented, however, that the "band of teeth in the upper jaw is of moderate breadth, without prolonged lateral portion"; whereas we find that the tooth band is actually posteriorly pointed.
A sample from the rio Jamari (INPA 9517), a rio Madeira tributary, agrees with the pigmentation pattern and most features of Rhyacoglanis pulcher except for having 7 branched pectoral-fin rays vs. the 5-6 rays in the type series.Unfortunately, with only two specimens from the rio Jamari and three from the type locality, it is uncertain whether this difference represents intraspecific variation or is an indication of an undescribed species of Rhyacoglanis in the rio Madeira.We tentatively identify the Madeira population as R. cf.pulcher pending study of additional specimens from those regions.Mees (1974) proposed P. variolosus to be a synonym of P. pulcher based on the features reported by Miranda-Ribeiro (1914).However, the type locality of P. variolosus is Coxim, rio Taquary, Mato Grosso State, in a different hydrographic basin than that of P. pulcher.Examination of part of the syntype series of P. variolosus (lectotype MNRJ 818 and paralectotype MNRJ 16245), and of the description of the species by Miranda-Ribeiro (1914), shows that P. variolosus has at least two of the known synapomorphies of Rhyacoglanis, although we were not able to confirm the number of vertebrae, even via radiography.Since our analysis did not allow us to unequivocally confirm the synonymy of P. variolosus with P. pulcher, we prefer to maintain it as tentatively valid until more specimens from the rio Taquary become available.

Rhyacoglanis seminiger, new species
urn:lsid:zoobank.org:act:8F27E9DD-CED6-402D-A6F6-EAAB04914D0B Figs. 11-12; Tab. 5 Holotype.LIRP 12466, 74.2 mm SL, Brazil, Mato Grosso, Sapezal, rio Tapajós basin: rio Juruena, Pequena Central Hidrelétrica Cidezal, 13º22'39"S 59º00'57"W, 3 Jun 2010, R. J. Hilário. . Brazil. Mato Grosso. LIRP 8042, 9, 48.3-74.8 mm SL, collected with holotype. MZUEL 14123, 2, 60.4-64.8 mm SL, collected with holotype. MZUSP 82085, 3, 44.4-70.4Description.proportional measurements are given in Tab. 5. Body depressed from snout to dorsal-fin origin, progressively compressed from that point to caudal-fin base.Dorsal profile of head and body slightly convex and posterodorsally nearly straight from snout tip to dorsal-fin origin; dorsal-fin base slightly posteroventrally nearly straight; profile nearly straight from terminus of dorsal-fin base to adipose-fin origin.Ventral profile of head and body convex overall from lower-jaw margin to anus; approximately straight from anus to posterior limit of anal-fin base.Caudal peduncle profile concave dorsally and ventrally.Head depressed; slightly longer than wide.Anterior margin convex in dorsal view.Head with unculiferous tubercles mainly dorsally.Mouth terminal and wide; width more than one-half of HL.Upper and lower jaws of equal length.Lips thick and well developed, more so on lateral surface of lower jaw and proximate to rictus.Premaxillary tooth plate posterolaterally pointed.Anterior nostril positioned immediately posterior to vertical through rictus.Eye small, superior, covered by skin, positioned slightly posterior of anterior one-third of HL.Opercular membrane well developed; margin reaching pectoral-fin origin.Maxillary-barbel base enlarged.Tip of adpressed barbel reaching pectoral-fin origin but falling short of opercular margin.Tip of adpressed inner mental barbel slightly surpassing outer mental-barbel base but falling short of barbel tip.Tip of adpressed outer mental barbel reaching margin of opercular membrane.

Color in alcohol.
Ground color light brown with dorsal portion of head slightly darker and region over the adductor mandibulae muscle less intensely pigmented.Subtle transverse dark stripe sometimes present from nape to tip of post-cleithral process; when present stripe sometimes darker on nape.Dark subdorsal and subadipose bands conjoined into wide band extending from vertical through dorsal-fin origin nearly to vertical through posterior one third of adipose-fin base.Lightly pigmented horizontal blotch sometime present within band in region between verticals through dorsalfin base terminus and beginning of adipose-fin base.Light colored blotch present at adipose-fin origin.Dark caudalpeduncle band vertically elongate with undulate anterior border and biconcave posterior margin.Some specimens with e160132 [21] scattered dark dots over lightly colored regions of head and body.Contralateral dark bands conjoined ventrally anterior of pelvic fin, between pelvic and anal fins, and along caudal peduncle.Dorsal fin darkly pigmented other than for narrow, lightly colored band along anterodorsal margin; sometimes with lightly colored region on basal one-third.Adipose fin with dark central region.Caudal-fin lobes with dark stripes or small dots on distal one-half; dark pigmentation restricted to dorsal and ventral portions of upper and lower lobes, respectively.Anal fin with dark basal blotch anteriorly and dark stripe over posterior one-third; patches fused in some individuals.Pectoral fin with broad dark stripe extending over two-thirds of spine and covering progressively more of fin rays medially.Pelvic fin dark basally, followed by unpigmented transverse band and large dark band over most of rest of fin other than for unpigmented marginal stripe.

Geographical distribution.
Rhyacoglanis seminiger is only known from the rio Tapajós basin, Mato Grosso, Brazil.The species was collected in rapids of the rio Juruena and the rio Arinos, in the foothills of the Serra do Parecis (Fig. 4).

Ecological notes.
The upper rio do Sangue, where some of the paratypes were collected, has very fast-flowing clear waters over a substrate composed nearly exclusively of quartz sand and small rocks, with the river margins covered by riparian forest.The Serra do Parecis foothills hold potential for small hydroelectric power plants that could adversely impact rheophilic species such as R. seminiger.Indeed, the rio Juruena specimens originate at one such site (Pequena Central Hidrelétrica Cidezal).
Etymology.The specific name, seminiger, is an adjective from the Latin semi = half, and niger = black, in reference to the dramatically contrasting light vs. dark coloration pattern.
Conservation status.Few specimens of R. seminiger were obtained from collections, suggesting that the species may be naturally rare.The geographic distribution of R. seminiger in the rio Tapajós basin is probably wide, as the known localities cover a broad geographic region of approximately 90,000 km 2 .The construction of hydroelectric power plants potentially threaten R. seminiger, and may result in fragmentation of its distribution by destruction of its preferred habitat in rapids.However, considering the extent of occurrence exceeding 20,000 km 2 , and lack of evidence indicating current population decline or fluctuations, we recommend assigning an IUCN (2016) status for R. seminiger of Least Concern (LC).
Remarks.Pigmentation features, in particular the fusion of the subdorsal and subadipose bands allows the unequivocal identification of Rhyacoglanis seminiger.Some differences exist, however, in dorsal fin and body band coloration between the rio do Sangue (some individuals with light blotches; Fig. 12) and rio Juruena samples (nearly completely dark).This variation along with the disjunct geographic distribution suggests discrete populations with limited gene flow, or phenotypic plasticity to environmental differences.In the absence of samples from intervening regions, we tentatively consider these to be intraspecifically variable, or conspecifics.If additional samples demonstrate consistent differences, then the rio do Sangue populations may merit recogniton as a new species.
Comparative morphometry.The first three principal components axes account for 92.8% of the total variance, with the first axis accounting for 84.2%.All variable first axis loadings were positive and presumably of approximately equal magnitude, indicating it reflects the size component.The second and third principal components include positive and negative variable loadings, and help index morphological variation among individuals that helps to differentiate species (Fig. 13).Rhyacoglanis pulcher is easily discriminated along the third component, which indexes its greater anus to analfin distance, dorsal-fin spine length, posterior nostril distance, pectoral-fin spine length, and caudal-peduncle length (all positive loadings; Tab. 6).Rhyacoglanis paranensis and R. seminiger differ from R. epiblepsis and R. annulatus by their greater dorsal-fin spine length, postcleithral process length, body depth and pectoral-fin spine length (all of which load positively on the second axis) and the lesser anus to anal-fin distance, distance between the posterior nostril and the orbit and adipose-fin length (negative loadings in the second axis).Some specimens of R. paranensis differ from R. seminiger by having longer dorsal and pectoral-fin spines, but these species are overall morphometrically very similar.Rhyacoglanis annulatus and R. epiblepsis (Fig. 13) also share similar measurements.Tab. 6. Variables loadings on the three first axes of the principal components analysis of combined samples of R. anulatus (N = 2), R. epiblepsis (N = 25), Rhyacoglanis paranensis (N = 22), R. pulcher (N = 3) and R. seminiger (N = 9).Variables with greater loadings = *.Unculiferous tubercles in species of Rhyacoglanis.Unculi are unicellular keratinous projections, specialized skin structures found across the main groups of Ostariophysi (Roberts, 1982) and observed in all pseudopimelodids.All species of Rhyacoglanis have small epidermal unculiferous tubercles.These unculiferous tubercles have a mammiliform shape, are rounded to elliptical, covered by unculi of irregular penta-to heptagonal-shapes, have a prominent irregular shaped apex (Fig. 14a) .The length of their longest axis ranges from 60 to 120 μm (mean = 82.3±18.5 μm; N = 22).The unculiferous tubercles are usually more developed on the dorsal and lateral surfaces of the head and body with a highest density on the head, particularly the barbels, lips and around the orbit.On the dorsal, pectoral, pelvic and anal fins the unculiferous tubercles are limited to the rays.No unculiferous tubercles were detected ventrally on the abdomen.Unculiferous tubercles were observed in smaller specimens (16.0 mm SL, MZUSP 22505) indicating their presence is not related to sexual maturity.Unculiferous tubercles in R. annulatus and R. seminiger are larger and more conspicuous than in R. paranensis, R. epiblepsis and R. pulcher.Each unculus in R. paranensis and R. seminiger has several rounded projections with the one in the middle slightly larger (Fig. 14b).
Unculiferous tubercles tend to be most developed in substrate-dwelling Cypriniformes and Siluriformes inhabiting swift water habitats (Roberts, 1982).Tubercles likely decrease skin surface turbulence and, thus, reduce drag on the fish in a way comparable to denticles in shark skin (Oeffner, Lauder, 2012) and contribute to adaptation of Rhyacoglanis to its rheophilic ecology.

Phylogenetic analysis
Character descriptions.Forty-one morphological features are the basis of a phylogenetic analysis with two primary goals: 1) to test the hypothesis of the monophyly of the new genus and its position in the Pseudopimelodidae and related groups; and 2) to determine the interrelationships of the included species.Characters are discussed by morphological systems.See (S1 -Available only as online supplementary file accessed with the online version of the article at http:// www.scielo.br/ni)for phylogenetic character matrix.
2. Degree of development of unculiferous epidermal structures: (0) little developed; (1) well developed (CI 0.33; RI 0.33).e160132 [24] As mentioned above, unculiferous tubercles are absent or at best weakly developed in the outgroups (Heptapteridae, Pimelodidae, and Ictalurus punctatus).In Pseudopimelodus, Cruciglanis, Microglanis and Batrochoglanis these structures are very small and sparse, whereas they are very well developed in Cephalosilurus and Lophiosilurus.Rhyacoglanis demonstrates intrageneric variation in tubercle development with the structures poorly developed in R. paranensis, R. epiblepsis and R. pulcher vs. well developed in R. annulatus and R. seminiger.
Thin skin covers the pectoral-fin spine in the outgroup and pseudopimelodids except for Pseudopimelodus and Rhyacoglanis.Those two genera have thick skin covering the spine to a degree that it masks the anterior serrations.For this classification, visual inspection was carried out, wherein the thin skin has been identified as the anterior serrae and pectoral spine could be seen in preserved specimens.
The head coloration pattern is quite variable in pseudopimelodids, ranging from very light in Cephalosilurus and Lophiosilurus (the same as in the outgroup), through grey in Cruciglanis and Pseudopimelodus, to completely black in Batrochoglanis and Microglanis.The head in Rhyacoglanis is slightly darker than the ground body coloration, with a subtle reduction in the pigmentation over the adductor mandibulae muscle.This character is inapplicable in the outgroup.
Cephalosilurus, Lophiosilurus and the outgroup lack dark bands predorsally, including on the head.In Rhyacoglanis the head is slightly darker but the predorsal region remains light.A predorsal dark stripe is present in Pseudopimelodus, Cruciglanis, Batrochoglanis and Microglanis.
In Batrochoglanis and Microglanis the predorsal and subdorsal dark bands are completely fused, forming a large blotch on the anterior region of the body.Cruciglanis has the bands partially fused ventrally forming a V-shaped dark band.In Pseudopimelodus, the predorsal dark stripe is separated from the subdorsal dark band by a lightly colored area.The character is inapplicable in genera lacking a predorsal band.
Dark body bands are widespread in the Pseudopimelodidae vs. the outgroup.Cephalosilurus and Lophiosilurus have dark bands as juveniles, but lose them during further development.
9. Fusion of dark subdorsal and subadipose bands: (0) absent; (1) present (CI 0.50; RI 0.00) Separate dark subdorsal and subadipose bands are generally present in Pseudopimelodidae except for Batrochoglanis raninus and Rhyacoglanis seminiger in which these bands fuse along their proximate margins.This character is inapplicable in the outgroup which lacks such bands.
A limited number of black spots scattered laterally on the body is the common condition in the Pseudopimelodidae and outgroup.Large numbers of grey spots characterize Rhyacoglanis epiblepsis.Steindachneridion scriptum has scattered black dots and short lines but no small spots on the body.
A dark caudal-fin stripe is absent in the outgroup plus Cephalosilurus and Lophiosilurus.Such a stripe is present in Cruciglanis, Pseudopimelodus, Batrochoglanis, Microglanis and Rhyacoglanis.
Although dark caudal-fin stripes occur in various pseudopimelodids, a confluence of that pigmentation and the dark band in the middle of the caudal peduncle is only present in Rhyacoglanis.In Cruciglanis, the caudal fin is completely dark, except on its distal margin that is light.This character is inapplicable in the outgroups which lack caudal-fin stripes.

Jaws. 13. Bifurcated dorsolateral process on premaxilla: (0) absent; (1) present (autapomorphy).
A premaxilla with a bifurcated dorsolateral process is restricted to the Pimelodidae (Lundberg et al., 1991b) as confirmed herein.In the Pseudopimelodidae the process is small, elongate but not bifurcate or is inconspicuous.
According to Birindelli (2014), a posterolateral extension of the premaxilla is limited to the Pimelodidae, Heptapteridae, Pseudopimelodidae and a subset of the Auchenipteridae (Auchenipterus, Epapterus).Within the Pseudopimelodidae, this extension is absent in Microglanis.
Pseudopimelodus, Cruciglanis and Rhyacoglanis and all species of the outgroup have the anterior nostril distant from anterior margin of the mouth.In Batrochoglanis, Microglanis, Cephalosilurus, and Lophiosilurus the anterior nostril is located along the mouth margin.
The lateral ethmoid-autopalatine joint in the Pimelodidae is elongate; a condition considered synapomorphic for the family (Lundberg et al., 1991b).In Ictalurus punctatus; the Heptapteridae and the Pseudopimelodidae the joint is very short.
18. Autopalatine: (0) depth similar anteriorly and posteriorly; (1) depth greater posteriorly; spoon-shaped (CI 1.00; RI 1.00).Diogo et al. (2004) considered a spoon-shaped autopalatine with a rounded dorsoventrally expanded posterior region synapomorphic for the Pseudopimelodidae.In the outgroup, the autopalatine is of similar depth anteriorly and posteriorly; sometimes with the mid-dorsal and mid-ventral regions concave.These observations have been corroborated here.
In most species of Pseudopimelodidae, the second basibranchial lacks lateral extensions as in the outgroup, whereas it is cruciform in Cruciglanis (Ortega-Lara, Lehmann, 2006).
21. Metapterygoid form: (0) longer than wide; (1) as long as wide (CI 1.00; RI 1.00).Lundberg et al. (1991a) noted that species of the Pseudopimelodidae have a very short, quadrangular metapterygoid that is as long as wide, dorsally medially curved, and typically supported by a crest or rim.In the outgroup this bone is longer than wide.
A rounded fenestra in the lower portion of the quadrate that articulates with the posterior of the anguloarticular is generally present across the Pseudopimelodidae.This fenestra was termed a cavity by Silfvergrip (1996) in Rhamdia quelen.The terms foramen (p.26) or fenestra (p.226) were applied by Mo (1991) to this structure in Bagrus bayad.Members of the Pimelodidae and Ictalurus punctatus lack the fenestra.
According to Rocha (2012:102), gill rakers in the Siluriforms are usually distributed along the entire anterior margins of the first ceratobranchial.They are restricted to the posterior region of this bone in the Pseudopimelodidae.
In most Siluriformes, the mesocoracoid forms a small arch along the posterior face of the pectoral girdle (Birindelli, 2014).In Pseudopimelodus, the mesocoracoid arch is triangular and in other examined species it is thin and elongate.
The posterior cleithral process is small in most catfishes (Birindelli, 2014).In Pseudopimelodus, Cephalosilurus and Lophiosilurus this process is very short.In other genera of the Pseudopimelodidae and the outgroup, the process is elongate, sometimes approaching or reaching the vertical through the dorsal-fin origin in Rhyacoglanis and Microglanis.This character is inapplicable in taxa lacking the posterior cleithral process.
In outgroup species, the serrae of the anterior margin of the pectoral fin spine are shorter than those along the posterior margin.This condition also occurs in Pseudopimelodus, Cruciglanis, Rhyacoglanis paranensis, R. seminiger and R. pulcher.Other genera of the Pseudopimelodidae, R. annulatus and R. epiblepsis have anterior and posterior serrae of the same size.
e160132 [27] This character is quite variable across catfishes.Within the context of this phylogeny, it is noteworthy that all pseudopimelodids have short maxillary barbels vs. long barbels in the outgroup.
Phylogeny.A single tree resulted from the phylogenetic analysis, with consistency index of 0.71 and retention index of 0.82; demonstrating that few characters are homoplastic (Fig. 15; S2 -Available only as online supplementary file accessed with the online version of the article at http:// www.scielo.br/ni).In this phylogenetic analysis, the sister group of the Pseudopimelodidae was the Heptapteridae on the basis of three synapomorphies (22 (0> 1), 31 (0> 1), 37 (1> 0)).
The monophyly of Rhyacoglanis is supported by three synapomorphies (characters 5 (0> 1), 12 (0> 1), and 31 (1> 2)).The synapomorphies are: presence of a lightly colored area on the cheek, presence of a dark caudal-fin dark stripes confluent with the dark band on the middle of the caudal peduncle, and a reduction in the number of vertebrae, to a count of between 30-35.The phylogenetic hypothesis is only partially resolved intragenerically and indicates that Rhyacoglanis paranensis forms a polytomy with the clades R. epiblepsis plus R. annulatus (supported by character 27 (0>1), and R. pulcher plus R. seminiger (supported by character 28 (0> 1)).

Discussion
Taxonomy and diversity.Taxonomic problems centered on Rhyacoglanis are longstanding as documented in the synonymy of R. pulcher.Various new combinations for the species were proposed as authors grappled with issues of generic limits.Lundberg et al. (1991a) made progress in addressing this problem; however, the discovery of new genera by Ortega-Lara, Lehmann ( 2006) and herein along with the series of new species of Rhyacoglanis described in this paper demonstrates that this family still contains many taxa not yet discovered.The intraspecific variation in some Rhyacoglanis species, the limited available material of the genus, the major gaps in the known distribution of the genus, and the problems in collecting in the high energy settings preferred by these rheophilic species make it very likely that species of the genus remain undiscovered; a situation common for the Neotropical ichthyofauna (Vari, Malabarba, 1998).Phylogenetic reconstruction.Phylogenetic relationships between the Heptapteridae, Pimelodidae and Pseudopimelodidae are a problem that warrants continued attention.Monophyly of each of the families has been corroborated by morphological (Diogo et al., 2004;Diogo, 2007) and molecular data (Hardman, 2005;Sullivan et al., 2006;Sullivan et al., 2013), and evidence supporting monophyly of the superfamily composed of those three families, called Pimelodoidea, was presented by Sullivan et al. (2006).
A relationship between the Heptapteridae and Pseudopimelodidae proposed herein was advanced by Lundberg et al. (1991a) andBritto (2002).Our analysis supports this hypothesis with three characters, which are hypothesized as synapomorphies of the two families.The first is an anteroventral fenestra in the quadrate that accommodates the end of the posterodorsal process of the anguloarticular and facilitates lower jaw movement and mouth opening.A similar fenestra arose homoplastically in the Bagridae (Mo, 1991).The second character involving the low vertebral counts, is somewhat tentative, and may be refined when data from an increased number of species of the Heptapteridae and Pimelodidae are available.Low numbers of vertebrae demonstrate size-related homoplasy in the Pseudopimelodidae as observed in Microglanis and Rhyacoglanis, both of which have the lowest counts and smallest body size, but are not sister groups.Absence of lateral trabeculae in the gas bladder is the third character uniting the Heptapteridae and Pseudopimelodidae.It is of note that the absence of such structures may be plesiomorphic in the Siluroidei in so far as they are also absent in Diplomystidae (Marceniuk, Birindelli, 2010).In sum, much of the evidence supporting a sister relationship of the Pseudopimelodidae and Heptapteridae is equivocal and this question requires further study.Indeed, swim bladder morphology (Birindelli, Shibatta, 2011) and molecular (Sullivan et al., 2013) evidence indicates a sister relationship of the Pseudopimelodidae with the Pimelodidae rather than the Heptapteridae.
Monophyly of the Pseudopimelodidae as supported in this study was corroborated in prior publications by Lundberg et al. (1991a), Sullivan et al. (2006) and Sullivan et al. (2013).Four of the eight characters that support this relationship were highlighted by previous authors: absence of a dorsal hypohyal (Lundberg et al., 1991a), the foreshortened metapterygoid (Lundberg et al., 1991a), the spoon-shaped autopalatine (Diogo, 2004), and the distribution of gill-rakers along the first ceratobranchial (Rocha, 2012).Among the newly discovered characters, the presence of unculiferous tubercles was noted by Birindelli (2014), but its significance in the evolution of the Pseudopimelodidae was not discussed.Within the context of the Pimelodoidea, the form of the unculiferous tubercles resolves as a synapomorphy of the Pseudopimelodidae since this type of structure is absent in the Heptapteridae and Pimelodidae.The same reasoning applies to the dark body bands, low number of pectoral-fin branched rays and short maxillary barbels in the Pseudopimelodidae vs. the absence of that pigmentation, high number of branched rays and longer barbels in the Heptapteridae and Pimelodidae.
This study provides the best resolved intergeneric phylogenetic reconstruction for Pseudopimelodidae to date, with no polytomies and all branches supported by two or more synapomorphies.The hypothesized relationships are, in part, incongruent with those proposed by earlier authors.Our results demonstrate that the group consisting of Cruciglanis, Pseudopimelodus and Rhyacoglanis is the sister of the remainder of the Pseudopimelodidae with Cephalosilurus and Lophiosilurus forming the sister group of Batrochoglanis and Microglanis.Lundberg et al. (1991a) alternatively considered Pseudopimelodus (Zungaro therein) as the sister of all other genera of the Pseudopimelodidae (their study did not include the thenundescribed Cruciglanis and Rhyacoglanis).Genera of the Pseudopimelodidae were represented in that study by only one or two species and all but Cephalosilurus showed autapomorphies.Many of these autapomorphies resolve as synapomorphies with the inclusion of additional species (Shibatta, 1998).The consensus tree presented by Shibatta (1998) included a polytomy between Batrochoglanis, Microglanis and Cephalosilurus.Shibatta (2003b) later presented one of the equally most parsimonious trees wherein Pseudopimelodus is sister of Microglanis + Batrochoglanis and Cephalosilurus + Lophiosilurus.Ortega-Lara, Lehmann (2006) added characters to Shibatta's (1998) matrix yielding a more resolved intrafamilial phylogeny, but in which Cephalosilurus and Lophiosilurus are sister to all other genera.Most recently, Birindelli, Shibatta (2011) presented two alternative phylogenetic hypotheses based on gas bladder features.These partly corroborate Ortega-Lara, Lehmann's (2006) hypothesis if the Pimelodidae is designated as outgroup.When, however, the outgroup is the Heptapteridae, the obtained relationships are most similar to Shibatta's (1998) hypothesis, including incomplete resolution of intergeneric relationships.The molecular analysis of Sullivan et al. (2013) yielded a scheme of relationships that differs greatly from prior morphology-based hypotheses, with Batrochoglanis sister to a clade formed by Cephalosilurus, Lophiosilurus and Pseudopimelodus.
We find Rhyacoglanis to be monophyletic and sister to Cruciglanis and Pseudopimelodus.This agrees in part with the Shibatta (1998) hypothesis in that Pseudopimelodus and Rhyacoglanis constitute a monophyletic group (Rhyacoglanis being represented in the Shibatta study by Pseudopimelodus pulcher).Birindelli, Shibatta (2011) found no differences in the gas bladder morphology of Pseudopimelodus pulcher (=Rhyacoglanis pulcher) vs. the examined species of Pseudopimelodus as that genus is treated herein, and Cruciglanis.In that study, as in this, the evidence supports the hypothesis of a sister relationships of Cruciglanis, Pseudopimelodus and Rhyacoglanis.
Diagnosis.Rhyacoglanis paranensis differs from R. annulatus by possessing a uniformly dark caudal peduncle band (vs. a band with an unpigmented central region), a wide subdorsal band (vs. a narrower band), a lower number of total vertebrae(31-33 vs. 34-35), a greater distance between the pelvic-fin and anus (9.9-17.3 vs. 8.2-9.6%SL), and a shorter distance between the anus and anal fin (6.5-12.7 vs. 15.8-16.2%SL).Rhyacoglanis paranensis is differentiated from R. epiblepsis by the pointed caudal-fin lobes (vs.rounded lobes), presence of only a few dark body spots (vs.many body spots of less intense pigmentation).Rhyacoglanis paranensis differs from R. seminiger by possessing distinctly separated subdorsal and subadipose bands (vs.fused bands), continuity between dark pigmentation on the caudal-fin lobes (vs.separation of the pigmentation on those lobes) and presence of discrete, dark transverse pectoral and pelvic-fin stripes (vs.fins largely uniformly dark).Rhyacoglanis paranensis differs from R. pulcher in the lack of dorsal and ventral confluence between the dark subdorsal and subadipose bands (vs.dorsal and ventral continuity of those bands), in the lack of confluence between subadipose and caudal-peduncle bands (vs.dorsal and ventral continuity of those bands) and possession of lower number of total vertebrae(31-33 vs. 33-35).Description.Body proportions in Tab. 3. Body depressed from snout tip to dorsal-fin origin; progressively more compressed from that point to caudal-fin base.Dorsal profile of head and anterodorsal portion of body nearly straight from snout tip to dorsal-fin origin but slightly concave along occipital region.Dorsal-fin base nearly straight with slight posteroventral incline.Body profile nearly straight from end of dorsal-fin base to adipose-fin origin.Ventral profile of head and body convex from lower jaw margin to end of anal-fin base, almost straight from anus to anal-fin origin.Caudal peduncle profile concave dorsally and ventrally.
Rhyacoglanis seminiger differs from all congeners in having the dark subdorsal and subadipose bands seamlessly conjoined (vs.completely separate or joined only dorsally and ventrally by narrow horizontal connecting extensions).Rhyacoglanis seminiger differs from R. annulatus in the uniformly dark caudal-peduncle band (vs.band with an unpigmented central section) and total vertebrae (32-33 vs. 34-35).Rhyacoglanis seminiger can be differentiated from R. epiblepsis by the pointed caudal-fin lobes (vs.rounded lobes), lack of intensely dark body spotting (vs.such spotting) and weak serrations limited to the base of the anterior margin of the pectoral-fin spine (vs.well developed serrations along the entire anterior margin).Rhyacoglanis seminiger additionally differs from R. pulcher in having 32-33 vertebrae (vs.34-35).
Conservation status.The conservation statuses of the new species were assesed according to criteria proposed by International Union for Conservation of Nature and Natural Resources for Red List Categories (IUCN, 2016).