Microglanis carlae, a new species of bumblebee catfish (Siluriformes: Pseudopimelodidae) from the río Paraguay basin in Paraguay

Microglanis carlae, new species, is described from the río Paraguay basin and distinguished from its congeners by the following combination of characters: paired and anal fins mottled or with thin faint bands, trunk with dark-brown saddles, anterior margin of pectoral spine with serrations retrorse proximally and antrorse distally, tip of pectoral spine as a distinct bony point, continuous portion of lateral line reaching vertical through last dorsal-fin ray, caudal peduncle with irregularly shaped, faint to dark blotch, maxillary barbel surpassing vertical through dorsal-spine origin, and dark bar on posterior flank continuous from base of adipose fin to that of anal fin. The new species is included in the Microglanis parahybae species complex on the basis of color pattern.


Introduction
The genus Microglanis was proposed by Eigenmann (1912) and currently contains 16 valid species (Shibatta 2003a;Shibatta, 2007).This genus comprises catfishes that never grow larger than 110 mm SL, and occur from trans-Andean drainages in Peru and Ecuador eastward to the Orinoco and Amazon basins, Guyana and southward to the río de la Plata basin, Argentina (Shibatta, 2003a;Shibatta & Benine, 2005).Shibatta (2003b) characterized Microglanis by its wide mouth (gape width same as head width), short maxillary barbel (occasionally reaching pectoral-fin origin), small eye without free orbital margin, absence of axillary pore near posterior insertion of pectoral fin, a dark saddle straddling supraoccipital area to the end of dorsal-fin base, premaxillary dental plate with rounded lateral margin, and thin mesocoracoid arch.
During inventory field studies conducted by staff of the CZCEN in the arroyo Yacaré (left bank tributary of río Tebicuary, río Paraguay basin), Paraguay, an additional undescribed species of Microglanis was collected, and is described herein.This is the first species of Microglanis to be described from the río Paraguay basin.

Material and Methods
Measurements were taken point-to-point under a stereomicroscope with a digital caliper to the nearest 0.1 mm on the left side of the specimen following Malabarba & Mahler (1998), Bertaco & Cardoso (2005), and Mori & Shibatta (2006).Measurements are expressed as percents of standard length (SL), except subunits of the head, which are recorded as percents of head length (HL).
In the description, each count is followed by its frequency in parentheses, and counts for the holotype are indicated by an asterisk.Counts of vertebrae, pleural ribs, branchiostegal rays, anal fin proximal and distal radials, and procurrent cau-dal-fin rays were based on three cleared and stained (c&s) specimens prepared according to Taylor & Van Dyke (1985).Vertebral counts include all rib-bearing centra but do not include any elements of the anterior, complex centrum (without ribs); the compound caudal centrum (pleural 1 + ural 1) is counted as one.The names "rio Paraguai and rio Uruguai" are used for these rivers when they occur in Brazilian territory (Portuguese language), and "río Paraguay and río Uruguay" for when they occur in other South American countries (Spanish language).
Microglanis garavelloi (recently described from upper rio Paraná basin) and M. parahybae (rio Paraíba do Sul basin) were compared to the new species using Size-Free Canonical Variate Analysis (SFCVA) in order to test hypothesized differences among the species and to identify diagnostic characters.The program PAST (Hammer et al., 2001) was used to calculate the SFCVA; option MANOVA/CVA used with normalized size and log transformed characters to produce a scatter plot of specimens along the first two canonical axes, producing maximal and second to maximal separation between all groups (multigroup discriminant analysis).

Microglanis carlae, new species
Figs. Diagnosis.The following combination of characters distinguishes Microglanis carlae from its congeners: paired and anal fins mottled or with thin faint bands, trunk with darkbrown saddles, anterior margin of pectoral spine with serrations retrorse proximally and antrorse distally, tip of pectoral spine as a distinct bony point, continuous portion of lateral line reaching vertical through last dorsal-fin ray, caudal peduncle with irregularly shaped, faint to dark blotch, maxillary barbel surpassing vertical through dorsal-spine origin, and dark bar on posterior flank continuous from base of adipose fin to that of anal fin.
Microglanis carlae is further or specifically distinguished from M. ater, M. nigripinnis, and M. pellopterygius by having paired and anal fins mottled or with thin faint bands (vs.wide dark bands); from M. variegatus by having the trunk with dark-brown saddles (vs.mottled); from M. zonatus by having anterior margin of pectoral spine with serrations retrorse proximally and antrorse distally (vs.all retrorse except ultimate serration on one pectoral spine in holotype according to description and illustrations in Eigenmann & Allen, 1942: 89, pl. 3, figs. 1-2); from M. secundus by having the tip of pectoral spine as a distinct bony point (vs.tip of pectoral spine soft, not as distinct bony point, but implanted between two serrations, one straight, pointing outwards from anterior margin and the other curved, pointing backwards from posterior margin); from M. iheringi by having continuous portion of lateral line reaching vertical through last dorsal-fin ray (vs.reaching vertical through adipose-fin origin); from M. poecilus by having a caudal peduncle with irregularly shaped, faint to dark blotch (vs.triangular); from M. cibelae, M. cottoides, M. eurystoma, and M. malabarbai by the wider head, 91.6-108.1% of HL (vs.60.2-70.1% in M. cibelae, 60.0-72.1% in M. cottoides, 50.9-71.8%in M. eurystoma, and 61.1-72.4% in M. malabarbai), maxillary barbel surpassing vertical through dorsal-spine origin (vs.not reaching vertical through dorsalspine origin), and the dorsal lobe of caudal fin slightly longer than ventral lobe (vs.lobes equal in size); from M. parahybae by having 7 pleural ribs (vs.6), and a dark bar on posterior flank continuous from base of adipose fin to that of anal fin (vs.not reaching blotch on base of anal fin); from M. garavelloi and M. leptostriatus by having a shallower caudal peduncle, depth 8. , dark bar on posterior flank continuous from base of adipose fin to that of anal fin (vs.not reaching blotch on base of anal fin), and by having caudal fin weakly forked (vs.emarginate).In addition, M. carlae differs from M. leptostriatus by the absence (vs.presence) of dark stripe along the axis of each gill filament, and differs from M. pataxo by having a wider head, 91.6-108.1% of HL (vs.58.2-64.7% in M. pataxo), maxillary barbel surpassing vertical through dorsal-spine origin (vs.reaching pectoral-spine origin), and dark bar on posterior flank continuous from base of adipose fin to anal fin (vs.not reaching blotch on base of anal fin).
Description.Morphometric data summarized in Table 1.Head and anterior portion of body depressed, becoming laterally compressed from pectoral girdle towards caudal region.Greatest body depth at dorsal-fin origin (14.1-21.0% of SL), greatest body width at pectoral-fin base (25.1-30.6% of SL).Dorsal profile of head and anterior body straight or gently convex, ventral profile gently convex.Head approximately as wide as long (width 91.6-108.1% of HL), anterior margin broadly   Post-Weberian vertebrae 28(2) or 30(1).Weberian complex with centra 1-5 fused, and ventrally open channel for aortic passage; transverse process 4 with anterior and posterior pointed processes; transverse process 5 pointed and shorter than preceding.Pleural ribs 7(3), becoming progressively smaller antero-posteriorly.
Color in alcohol.Head dark brown in dorsal view with two small yellowish blotches near posterior nares and small yellowish tan oblique blotch on posterior cheek extending ventroposteriorly from below eye.Large continuous transverse yellowish tan bar across occipital region between opercular openings.Barbels pale with brown spots.Body with dark brown saddles separated by yellowish tan interspaces.Anteriormost saddle in nuchal region (anterior to dorsal-spine origin), second below dorsal-fin base; first two saddles broadly confluent middorsally except for yellowish tan oval spot at origin of dorsal-fin spine, and confluent ventrally just above horizontal through pectoral-spine origin.Third dark brown saddle extending longitudinally from interdorsal region to middle of adipose-fin base, interrupted middorsally by tan oval patch over anterior base of adipose fin; saddle continuing ventrally as bar on posterior flank and usually reaching dark blotch on base of anal fin (bar faded below midlateral in five specimens).Broad, irregularly shaped dark brown blotch on caudal peduncle largely enclosing two small yellowish tan elliptical spots: middorsal spot located between vertical through posterior tip of adipose fin and base of caudal fin; midventral spot extends between posterior base of anal fin and base of caudal fin.Ventral surfaces of body and head pale yellow with very small tan to light brown spots and blotches.
All fins hyaline with brown spots or bands.Dorsal fin with dark brown base and broad dark brown submarginal band across fin spine, rays and membranes.Adipose fin with narrow dark brown blotch at center along base flanked anteriorly and posteriorly by yellowish tan blotches; distal margin pale.Pectoral fin with dark brown mottling on spine and middle portions of rays and membranes.Pelvic fin lightly speckled with small dark spots.Anal fin with dark blotch on bases of rays 3-7, and dark brown crescentic band on middle portions of rays and membranes.Caudal fin with dark brown (sometimes inconspicuous) vertical band continuous across middle portions of dorsal and ventral lobes.
Etymology.The specific name is in honor of Carla Simone Pavanelli (Universidade Estadual de Maringá, Núcleo de Pesquisas em Limnologia, Ictiologia e Aqüicultura) for her contributions to Neotropical Ichthyology.
Ecological notes.The stomach contents of two specimens included algae and insect larvae.Analysis of the reproductive condition in six specimens indicated adult males to be about 23 mm SL and females to be about 25 mm SL.One specimen was infected in the ventral region of the head by a parasite, the metacercaria stage of Digenea (Trematoda).Species found in moderately flowing sections of streams with dark brown water and bottoms of sand and mud; specimens collected with a dip net under floating vegetation at a depth

Discussion
Size-Free Canonical Variate Analysis (SFCVA) of measurements (Fig. 5) discriminate between specimens of M. carlae and two species that are geographically nearby and considered to be morphologically similar: M. garavelloi (from the upper rio Paraná basin) and M. parahybae (from the rio Paraíba do Sul basin).The first and second canonical axes account for 58.7% and 41.3%, respectively, of the variation in the original data.The characters that discriminate the new species from M. garavelloi are a longer pelvic-fin to anal-fin distance and greater orbital diameter (Table 2; most negative values in first canonical axis) and a shallower caudal-peduncle, shorter pelvic-fin, and shallower depths for body at dorsal fin, body at beginning of adipose fin and head (most positive values in the first canonical axis).Microglanis carlae is discriminated from M. parahybae by having a greater interorbital width, and a longer pelvic fin and longer maxillary barbel (most positive values in second canonical axis) and a shorter adipose-fin base and shorter dorsal spine (most negative values in second canonical axis).
The río de La Plata system (Paraguay, upper Paraná and Uruguay river basins) has the highest diversity of Microglanis with a total of five species known from the watershed: Microglanis carlae (here described from the río Paraguay basin), M. garavelloi (upper rio Paraná basin) and M. cottoides, M. eurystoma, and M. malabarbai (rio Uruguai basin) (Shibatta, 2007).Britski et al. (1999) included Microglanis cottoides in their identification manual on fishes from the Pantanal (upper rio Paraguai basin in Brazil); but Malabarba & Mahler (1998) and Shibatta (2003a;2007) reported that the distribution of this species was restricted to the laguna dos Patos and Uruguai basins.A Microglanis specimen from the rio Cuiabá, upper rio Paraguai basin (NUP 3533), does not correspond to nearby M. carlae or M. cottoides, and is possibly another new species.Mori & Shibatta (2006) suggested the Microglanis parahybae species complex for species with the following combination of characters: body light brown with first and second dark brown saddles not extending ventrally below   horizontal through pectoral-fin origin; light oval spot located below dorsal-fin spine; third dark brown saddle, not reaching dark blotch on base of anal fin; and caudal fin with dorsal lobe slightly longer than ventral lobe.Microglanis carlae is added to this species complex because it shares three of the four characters.Microglanis carlae differs by having the third dark brown saddle usually continuing ventrally as a bar on posterior flank and reaching dark blotch on base of anal fin (bar faded below midlateral in five specimens).The M. parahybae species complex includes two species in rivers along the Brazilian coast, M. pataxo (State of Bahia) and M. parahybae (State of Rio de Janeiro), two species in the interior of Brazil, M. leptostriatus (rio São Francisco) and M. garavelloi (upper rio Paraná), and now one species in the interior South American plateau: M. carlae (río Paraguay in Paraguay).The distribution of this species complex is extended to the upper portions of the rio Paraguai basin by the aforementioned specimen of Microglanis sp.(NUP 3533).Although species of this complex share similar color patterns, only a phylogenetic analysis can determine whether these species are closely related.
of 1.5 to 2 m.The arroyo Yacaré (Fig.4, type locality) is a deep stream of dark brown water with patches of floating vegetation of Eichhornia sp.along the margins; riparian vegetation mainly grass for pasture with small patches of original shrubs, lianas and palm trees of Copernicia alba.

Table 1 .
Morphometric data for Microglanis carlae, n = 27.Minimum and maximum includes data for holotype and paratypes.

Table 2 .
First two size-free Canonical Variate axes (CV 1 and CV 2) from the analysis of combined samples of Microglanis carlae, M. garavelloi and M. parahybae (Total = 88 specimens).