Ancistrus verecundus, Fisch-Muller & Cardoso & da Silva & Bertaco, 2005

Fisch-Muller, Sonia, Cardoso, Alexandre R., da Silva, José F. P. & Bertaco, Vinicius A., 2005, Two new Amazonian species of armored catfishes (Siluriformes: Loricariidae): Ancistrus verecundus and Ancistrus parecis, Neotropical Ichthyology 3 (4), pp. 525-532 : 527-529

Ancistrus verecundus , new species

Figs. 1-2 , 4a

Holotype. MCP 35572 (male, 53.7 mm SL), Brazil: Rondônia: Vilhena:igarapé Piracolina, about 6 km W of Vilhena, on the road BR-364, upper rio Madeira basin, 12°43’33"S 60°11’34"W, 14 Jul 2004, R. E. Reis, P.A. Buckup,A. R. Cardoso & E. H. Pereira.

Paratypes. MCP 35573, 10 (5 measured), 29.4-54.6 mm SL, MHNG 2664.033, 3 (2 measured), 33.2-51.9 mm SL, collected with the holotype .

Diagnosis. Ancistrus verecundus is easily distinguished from all congeners, except A. jataiensis , A. parecis , A. reisi , and A. tombador by the absence of an adipose fin which is replaced by a series of 3 to 5 median, unpaired platelets forming a low postdorsal ridge. Ancistrus verecundus differs from all congeners lacking an adipose fin, except for A. tombador , by the naked margin of snout broad and the reduced development of snout tentacles in both sexes (usually absent), and by the presence of two or more plates of the dorsal plate series between the end of the postdorsal ridge and the origin of the first dorsal procurrent caudal-fin spine ( Fig. 4a ) (vs. one or none). Ancistrus verecundus is distinguished from A. tombador by the head depth at supraoccipital (17.9-19.3 vs. 15.6-16.9% SL), cleithral width (31.4-33.1 vs. 27.5-31.2% SL), interorbital width (15.9-16.8 vs. 12.7-15.1% SL), and by the base of the first anal-fin pterygiophore covered by skin (vs. exposed).

Description. Morphometric and meristics in Table 1. Head and body depressed. Dorsal profile of head convex from tip of snout tip to posterior tip of supraoccipital, nearly straight to slightly convex from tip of supraoccipital to dorsal-fin origin, straight and posteroventrally slanted along dorsal-fin base, slightly concave from end of dorsal-fin base to median platelets replacing adipose fin, more concave from that point to last procurrent caudal-fin ray. Ventral profile straight, caudal peduncle slightly concave. Greatest width of body at cleithrum, with body narrowing progressively from cleithrum to end of caudal peduncle. Caudal peduncle very low and slender.

Snout rounded with relatively broad naked margin in both sexes (much wider than distance between naked margin and nostril in specimens hypothesized to be males, including holotype; nearly as broad as distance between naked margin and nostril in specimens hypothesized to be females, including largest specimen examined). Thin median row of platelets extends up to, or nearly to, anterior extremity of snout. Tentacles usually absent in both sexes in specimens examined.

Eye small, dorsal margin of orbit slightly elevated, interorbital area slightly concave. Exposed part of opercle roughly triangular with posterior part slightly elongated; dermal plates of postopercular area never numerous, generally contiguous with pterotic-supracleithrum, sometimes few smaller plates anteriorly, leaving large naked area around opercle. Hypertrophied cheek odontodes numerous and short, none reaching posterior margin of adpressed opercle; base fleshy and sometimes thick.

Oral disk roughly circular, lips covered with minute papillae. Lower lip large but not reaching pectoral girdle, its border covered with very small papillae. Maxillary barbel short, about as long as buccal papilla. Mandibular tooth row short, premaxillary tooth row slightly wider; teeth bifid, main cusp large; lateral cusp minute, pointed, never reaching more than onethird length of mesial cusp.

Supraoccipital with margins between surrounding bones and plates usually not clearly visible. Nuchal plate small and curved. Five series of lateral plates; mid-dorsal, and mid-ventral series ending at level of end of series of platelets replacing adipose fin. Last plate in median series rarely smaller than penultimate plate. Odontodes present on body plates except along dorsal-fin base, and on widely extended area below anal fin; odontodes generally short, only very slightly longer on ventral margin of opercle and on pectoral-fin spine of males. Abdomen entirely devoid of plates. Base of first anal-fin pterygiophore covered by skin (without preanal platelet-like element).

Dorsal-fin origin situated slightly anterior to vertical through pelvic-fin insertion; dorsal fin short, tip of adpressed fin not reaching series of median platelets. Area usually occupied by adipose fin covered by series of 3 to 5 small median platelets forming low postdorsal ridge. Two or more plates of dorsal plate series between end of postdorsal ridge and origin of first dorsal procurrent caudal-fin spine ( Fig. 4a ). Pectoral spine extending to anterior one-third of pelvic spine. Anal fin short. First anal-fin pterygiophore covered by skin. Caudal fin short, slightly concave. Fin-ray formulae: dorsal i,7 (7) or i,8 (1); pectoral i,6; pelvic i,5; anal i,4; caudal i,13,i (1) or i,14,i (7). Vertebrae: 27 (1).

Color in alcohol. Body reddish-brown, ventral portion of caudal peduncle paler. Body with irregularly distributed dark spots dorsally. Some specimens with numerous small and inconspicuous paler spots, limited to naked margin of snout (holotype), or more extending extensively on head. Lips yellowish. Ventral surface of head and abdomen plain or with coalescent spots forming thin and ill-defined whitish vermiculations. Fin rays generally reddish-brown with scattered dark-brown spots; membranes dark-brown when pigmented. Spots on distal one-half of dorsal and caudal fins sometimes forming bands ( Fig. 2 ).

Distribution. Ancistrus verecundus was collected in a small river of the upper rio Madeira basin, in the state of Rondônia, Brazil ( Fig. 1 ).

Etymology. From Latin, verecundus , meaning bashful, modest, in allusion to the absence or reduced development of tentacles on the snout.

Figures

Fig. 1. Collecting localities of Ancistrus verecundus (circle) from the upper rio Madeira, Ancistrus parecis (squares) and Ancistrus tombador (diamond) from the upper rio Tapajós, and Ancistrus jataiensis (triangle) and Ancistrus reisi (star), from the upper rio Tocantins. Open symbols represent type localities. Some symbols represent more than one locality.

Fig. 2. Ancistrus verecundus, MCP 35572, holotype, male, 53.7 mm SL; igarapé Piracolina, upper rio Madeira basin, Vilhena, Rondônia, Brazil.

Fig. 4. Dorsal view of caudal peduncle in (a) Ancistrus verecundus, MCP 35573, paratype, 54.6 mm SL and (b) Ancistrus parecis, MCP 35570, holotype, 59.5 mm SL.Arrows indicate dermal plates of dorsal series of plates between the end of postdorsal ridge and the origin of the first plate-like procurrent caudal-fin ray.