Otothyropsis marapoama, Ribeiro & Carvalho & Melo, 2005

Ribeiro, Alexandre C., Carvalho, Murilo & Melo, Alex L. A., 2005, Description and relationships of Otothyropsis marapoama, a new genus and species of Hypoptopomatine catfish (Siluriformes: Loricariidae) from rio Tietê basin, southeastern Brazil, Neotropical Ichthyology 3 (4), pp. 489-498 : 491-494

Otothyropsis marapoama , new species Fig.1

Holotype: LIRP 5640 , 38.5 mm SL, Brazil, São Paulo, rio Tietê basin, Município de Marapoama, ribeirão Cubatão , road between Marapoama and Elisiário (21º11’35"S 49º07’22"W) ( Fig.2 ), 10 Feb 2003; A. L. A. Melo.

Paratypes: LIRP 4621 , 3 , 27.6-32.3 mm SL (1, 27.6 mm SL c&s), collected with holotype ; MZUSP 87892 , 1 , 28.6 mm SL, collected at type locality, 14 Jul 2004, A. L.A. Melo, A. C. Ribeiro, M. Carvalho & A. K. Takako ; LIRP 5641 , 20 , 18.0-29.0 mm SL (4, 19.8-29.0 mm SL c&s; 4 stained with alizarin red solution) ; MZUSP 87893 , 10 , 18.7 -23.0 mm SL , MCP 38303, 10 , 18.2 - 22.8 mmSLandDZSJRP 7887, 8, 19.3-21.9 mmSL, Brazil, SãoPaulo , rio Tietê basin, Município de Catanduva , Sítio Cubatão, córrego Cubatão (21º14’53.4"S 49º01’18.8"W), 14 Jul 2004, A. L. A. Melo, A. C. Ribeiro, M. Carvalho & A. K. Takako .

Diagnosis. As for genus.

Description. Morphometrics and meristics given in Tables 1 and 2 respectively. Dorsal profile of body gently arched from snout tip to dorsal-fin origin; slightly concave to straight at dorsal-fin base; straight from end of dorsal-fin base to cau- dal-fin origin. Ventral profile of body straight to slightly concave from snout tip to base of pectoral fin; straight from that point to anal-fin origin, slightly concave at anal-fin base, and then straight from end of anal-fin base to caudal-fin base. Greatest body depth at dorsal-fin origin. Least body depth at caudal peduncle. Greatest body width at opercular or cleithral regions. Trunk gradually tapering to caudal-fin base. Trunk and caudal peduncle rounded (smaller individuals) to slightly square (in the holotype, the larger specimen with 35.8 mm SL) in cross section, trunk slightly flattened at base of dorsal and pectoral fins and laterally compressed caudally. Body progressively narrowing caudally from cleithrum. Head wide and rounded anteriorly. Interorbital region flat to slightly convex, with latter margin slightly elevated. Snout straight at mid-line and concave in the region anterior to nares in both sides of head. Eye laterally placed. Superior margin of orbit conspicuously elevated, forming a ridge around orbital margin. Region of pterotic-supracleithrum posterior to orbital margin slightly depressed. Lateral wall of pterotic pierced by enlarged fenestrae, which are visible externally ( Fig. 3 ).

Body surface without well-developed crests. Body and abdomen entirely covered by plates, except for small ventral surface in front of anus, region overlying opening of swim bladder capsule, and around pectoral, pelvic, and anal-fin insertions. Rostral plates well-developed and projecting ventrally over the ventral margin of snout ( Fig. 3b ). Head and body plates covered with pointed odontodes, mostly uniform in size and distribution, not arranged in conspicuous rows. Odontodes from dorsal and ventral surface of snout slightly larger than remaining ones. Odontodes at tip of supraoccipital and compound petrotic-supracleithrum-posttemporal slightly larger than remaining odontodes of head, but not forming conspicuous crests ( Fig. 3 ). Pectoral girdle almost completely exposed, except for small median area covered by skin ( Fig. 4a ). Pelvic girdle with solid basipterygium anteriorly ( Fig. 4b ).

Tip of adpressed pectoral fin reaching to middle of pelvic fin, with posterior margin slightly rounded. Well-developed slit present posterodorsally to pectoral insertion. Tip of adpressed pelvic fin reaching anus. Pelvic-fin spine smaller than branched rays and supporting medially projected odontodes. Dorsal-fin origin at vertical behind end of pelvicfin base. Dorsal-fin spinelet small, with dorsal-fin locking mechanism non-functional. Adipose fin absent. Ventral caudal-fin lobe slightly longer than dorsal lobe.

Lips roundish, papillose. Maxillary barbel present. Teeth slender, bifid, with larger medial cusp bladelike and slightly rounded, and smaller lateral cusp minute and pointed.

Color in alcohol. Background color of dorsal surface of head and body dark gray to brown. Body, in larger specimens, completely covered by white spots, ranging in shape from vermiculated to ovoid and often coalescing with each other. Smaller specimens more regular gray to brown overall color pattern. On head, dark pigmentation more concentrated between nares, and along lateral head margin. On body, dark pigmentation concentrated at lateral regions. Ventral surface of body mostly unpigmented, with small scattered spots, which are more concentrated around oral disk and pectoralfin insertion.

Unbranched rays of dorsal, pectoral, pelvic and anal fins with five to seven, five to eight, two to five, and four to six dark transverse stripes, respectively. Branched rays of each of these fins with series of spots aligned in continuous transverse stripes. Caudal-fin coloration variable, with pattern ranging from striped along whole fin, to single large spot on fin base and scattered chromatophores distally. Ventral lobe of caudal fin usually more heavily pigmented than dorsal lobe. Etymology. The specific epithet marapoama is in reference to the county of the city in which the new species was collected. It is treated as a noun in apposition.

Distribution. Known from two nearby localities in the same stream along the middle stretch of the rio Tietê, a tributary of the rio Paraná of southeastern Brazil ( Fig. 2 ).

Figures

Fig. 1. Otothyropsis marapoama, holotype, LIRP 5640, 38.5 mm SL. Brazil, São Paulo, rio Tietê basin, Município de Marapoama, ribeirãoCubatão,off theroad between Marapoaraand Elisiário(21º11’35"S 49º07’22"W).Dorsal(a), lateral (b), andventral (c)views.

Fig. 2. Southeastern Brazil showing type-locality of Otothyropsis marapoama in the middle stretch of the rio Tietê basin (1: rio Tietê; 2: rio Grande; 3: rio Paraná; 4: rio Paranapanema; 5: rio Ribeira de Iguape; 6: rio Paraíba do Sul).

Fig. 3. Skull of Otothyropsis marapoama, paratype, LIRP 5641, 29.0 mm SL, a) dorsal view; b) lateral view.

Fig. 4. Otothyropsis marapoama, paratype, LIRP 5641, 29.0 mm SL, a) pectoral girdle and abdominal platelets in ventral view, anterior to top; b) basipterygium in dorsal view, anterior to top.