Ancistrus parecis, 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 : 529-531

Ancistrus parecis , new species

Figs. 1 , 3 , 4b

Holotype. MCP 35570 (male, 59.5 mm SL); Brazil: Mato Grosso: Campos de Júlio: rio Formiga (tributary of rio Juruena , upper rio Tapajós basin), on the road BR-364 (MT-235), between Campos de Júlio and Sapezal, 13°41’01"S 59°12’11"W, 13 Jul 2004, P. Lehmann, V. A. Bertaco, J. F. P. Silva & F. Langeani.

Paratypes. Brazil: Mato Grosso: Comodoro: MCP 35571 (2, 42.2-44.4 mm SL), MHNG 2664.034 (1, 44.4 mm SL), rio Juína, tributary of rio Juruena , upper rio Tapajós basin, on road BR- 364 about 45 km of the crossing point to Campos de Júlio and Sapezal , 13°47’59"S 59°29’20"W, same collectors and date as holotype .

Diagnosis. Ancistrus parecis differs from all its congeners except A. verecundus , A. jataiensis , A. reisi , and A. tombador by the absence of an adipose fin. A series of 4 to 6 small median, unpaired platelets forming a low postdorsal ridge covers the area otherwise occupied by the adipose fin. Ancistrus parecis differs from A. tombador and A. verecundus by the presence of tentacles on the snout of adults (vs. absence or reduction of tentacles), and by a lower number of plates of the dorsal plate series between the end of the postdorsal ridge and the origin of the first plate-like procurrent caudal-fin ray (one or none vs. two or more; Fig. 4 ). It is further distinguished from A. tombador by the predorsal length (45.3-47.1 vs. 42.7-45.1% SL), head depth at supraoccipital (18.7-19.4 vs. 15.6-16.9% SL), cleithral width (32.4-33-6 vs. 27.5- 31.2% SL), body width at dorsal-fin origin (27.8-30.5 vs. 22.8- 26.9% SL), caudal-peduncle length (25.6-27.9 vs. 29.4-32.4% SL), and the number of plates between the anal and caudal fins (9-10 vs. 11-12). Ancistrus parecis differs from A. reisi and A. jataiensis by a narrower mandibular tooth row (14.8- 17.0 vs. 19.4-24.0% HL), fewer teeth (50-59 vs. 62-80 on dentary and 47-55 vs. 61-80 on premaxillary), and by a lower caudal peduncle (8.5-9.4 vs. 9.6-10.7% SL), respectively.

Description. Morphometric and meristics in Table 1. Dorsal profile of head convex from snout tip to posterior tip of supraoccipital, nearly straight to slightly convex from supraoccipital tip to dorsal-fin origin, straight and posteroventrally slanted along dorsal-fin base, slightly concave from end of dorsal-fin base to median platelets in area otherwise occupied by 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, body narrowing progressively from that point to near caudal peduncle.

Snout rounded; plates delimiting posterior margin of naked area of snout irregularly placed; thin median row of platelets covering naked area up to or nearly to anterior extremity of snout. Naked margin of snout narrower than distance between naked margin and nostril in females, nearly as great as distance to nostrils in males, with fleshy tentacles (up to 30, in holotype). Tentacles placed along border of snout in two specimens; but also on dorsum of snout (only in holotype, 59.5 mm SL). Male of 44.4 mm SL with small tentacles arranged in one row bordering snout. Some tentacles branched in holotype.

Eye very small, dorsal margin of orbit slightly elevated and slightly convex. Exposed portion of opercle roughly triangular with posterior region slightly elongated; few dermal plates on postopercular area; plates generally contiguous with pterotic-supracleithrum, sometimes with few smaller plates anteriorly leaving large naked area around opercle. Hypertrophied cheek odontodes stout but neither numerous nor very long, with fleshy base sometimes long and thick, posterior odontodes reaching posterior one-half of adpressed opercle.

Oral disk roughly circular; lips covered with minute papillae; lower lip large but not reaching posteriorly to pectoral girdle, its border formed by unequal small flaps. Maxillary barbels, about as large as buccal papilla. Mandibular and premaxillary tooth rows equal in length or latter slightly longer; teeth numerous, bifid, main cusp large and long; lateral cusp minute, pointed, reaching more than one-third length of mesial cusp.

Supraoccipital with margins between surrounding bones and plates except median predorsal plate usually not clearly visible. Odontodes very short on head; central part of supraoccipital slightly granular. Nuchal plate and dorsal-fin spinelet exposed. Five series of lateral plates; mid-dorsal and mid-ventral series ending at level of end of series of platelets located in area occupied by adipose fin in most congeners. Last plate in median series rarely smaller than penultimate plate. Odontodes present on body plates except along dorsal-fin base and on a widely extended area below anal fin; odontodes of males slightly longer on ventral margin of opercle and on pectoral-fin spine. Abdomen entirely devoid of plates. First anal-fin pterygiophore either exposed and forming preanal platelet-like element (holotype) or covered by skin.

Dorsal-fin origin located slightly anterior to pelvic-fin origin; dorsal fin short; tip of fin falling short of median platelets occupying space otherwise occupied by adipose fin. Adipose fin absent, replaced by series of 4 to 6 small median platelets forming low postdorsal ridge. One plate (sometimes none) of dorsal plate series between end of postdorsal ridge and origin of first dorsal procurrent caudal-fin spine ( Fig. 4b ). Pectoral-fin spine curved and short, extending to anterior onefourth of pelvic-fin spine, and thickened in large specimens. Anal fin short. Caudal fin short, slightly concave. Fin-ray formulae: dorsal i,6 (1) or i,7 (3); pectoral i,6; pelvic i,5; anal i,4; caudal i,14,i. Vertebrae: 28 (2).

Color in alcohol. Ground coloration of body brown or reddish-brown, lower part of caudal peduncle paler. Ill-defined dark-brown and reddish or yellowish areas over body. Small, rounded or elongated lighter spots often present on snout but never very distinct. Ventral surface lighter; lips yellowish; belly light brown (rarely yellowish); when pigmented, chromatophores present on entire surface including central portion, with very ill-defined lighter spots. Fin rays generally dark brown and finely spotted with yellowish to orange, hyaline membranes unpigmented at least on central parts. Caudal fin with tips often yellowish to orange colored ( Fig. 3 ).

Distribution. Ancistrus parecis was collected in small rivers of the upper rio Tapajós basin, in the state of Mato Grosso, Brazil ( Fig. 1 ).

Etymology. The specific name parecis (a noun in apposition) refers to the Chapada dos Parecis, a plateau where the type locality is situated.

Key to the species of Ancistrus without an adipose fin.

1. Snout usually without tentacles in adults; two or more plates of the dorsal plate series between end of postdorsal ridge and origin of first dorsal procurrent caudal-fin spine ( Fig. 4a ) ................................................................................. 2

1’. Snout with tentacles in adults; one or no plate of the dorsal plate series between end of postdorsal ridge and origin of first dorsal procurrent caudal-fin spine ( Fig. 4b ) .............. 3

2. Body narrow (27.5-31.2% SL at cleithrum) and depressed (15.6-16.9% SL at supraoccipital); with preanal plateletlike element ......... A. tombador (upper rio Tapajós basin)

2’. Body wide (31.4-33.1% SL at cleithrum) and deep (17.9- 19.3% SL at supraoccipital); without preanal platelet-like element ............. A. verecundus (upper rio Madeira basin)

3. Length of mandibular tooth row 19.4-24.0% HL; caudalpeduncle depth 9.6-10.7% SL; teeth on dentary 62-80 and premaxilla 61-78 ................................................................... 4

3’. Length of mandibular tooth row 14.8-17.0% HL; caudalpeduncle depth 8.5-9.4% SL; teeth on dentary 50-59 and on premaxilla 47-55 ... A. parecis (upper rio Tapajós basin)

4. Predorsal length 43.8-46.4% SL; occipital depth 14.9-17.0% SL; caudal peduncle length 27.7-30.9% SL ....................... ..................................... A. reisi (upper rio Tocantins basin)

4’. Predorsal length 47.5-49.3% SL; occipital depth 17.0-19.5% SL; caudal peduncle length 24.6-27.1% SL ....................... ........................... A. jataiensis (upper rio Tocantins basin)

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. 3. Ancistrus parecis, MCP 35570, holotype, male, 59.5 mm SL; rio Formiga, upper rio Tapajós basin, Campos de Júlio, Mato Grosso, 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.