Lasiancistrus tentaculatus, Armbruster, 2005

Armbruster, Jonathan W., 2005, The loricariid catfish genus Lasiancistrus (Siluriformes) with descriptions of two new species, Neotropical Ichthyology 3 (4), pp. 549-569 : 565-567

Lasiancistrus tentaculatus , new species Fig. 9

Holotype. MCNG 19744, 147.6 mm SL, río Las Marias, near El Portrero , below the metal bridge, 09°05’N, 69°39’W, D. C. Taphorn, A. Flecker, B. Feifarek, L. Van Balen, 12 Nov 1986.

Paratypes. All collections Venezuela. Apure: INHS 28283, 44 (5 measured), 2 c&s, 52.9-76.8 mm SL, tributary to río Suripa, 36 km NE La Pedrera on highway 5, L. M. Page, B. M. Burr, P. A. Ceas, C. A. Taylor & S. R. Walsh, 6 Jan 1992. Carabobo, río Orinoco drainage: MCNG 15345, 1, 89.5 mm SL, caño Guamita, highway to los Naranjos, approximately 15 km from the crossroads, 10°02’50"N, 067°54’30"W, D. Taphorn, S. Reid, & C. Olds, 19 Oct 1986. Barinas, río Orinoco drainage: INHS 29866, 48 (1 measured), 6 c&s, 77.0 mm SL, caño Yaure, Yaure on highway 5, 36 km NE La Pedrera, 7°42’05"N, 71°17’77"W, L. M. Page, S. Huhndorf, & J. L. Crane, 26 Jan 1993. Cojedes, río Orinoco drainage: INHS 28988, 2, 49.0- 69.8 mm SL, río San Carlos WNW Las Vegas, 9°33’40"N, 68°38’89"W, J. W. Armbruster, D. C. Taphorn, L. M. Page, K. S. Cummings, C. A. Mayer, P.A. Ceas, C. A. Laird & M.H. Sabaj, 9 Jan 1993. INHS 29062, 6 (2 measured), 58.3-79.3 mm SL, río Camoruco, about 10 km NW Libertad, D. C.Taphorn, L. M. Page, K. S. Cummings, C. A. Mayer, P.A. Ceas, J. W.Armbruster, C. A. Laird & M. H. Sabaj, 9 Jan 1993. INHS 32030, 3 (1 measured), 67.3 mm SL, río San Carlos, 2 km W Las Vegas at caño Hondo, on rd. from Las Vegas to Libertad, 9°31’51"N, 68°39’39"W, J. W. Armbruster, M. H. Sabaj, K. S. Cummings & C.A. Mayer, 14 Jan 1994. J. W. Armbruster, P.A. Ceas, M. Campos, R. Suarez & J. A. Llerandi, 16 Jan 1995. Guarico, río Orinoco drainage: ANSP 163455, 1, 38.0 mm SL, Tributary of río Paya (tributary of río Guarico), 23 km S of San Juan de los Morros on Federal Highway 2, N. R. Foster, 29 Nov 1966. INHS 34617, 2, 59.6-68.9 mm SL, río San Jose, Parque Nacional Aguaro-Guariquito, 9°28’55"N, 66°53’19"W, J. W. Armbruster, P. A. Ceas, M. Campos, R. Suarez & J. A. Llerandi, 16 Jan 1995. Portuguesa, río Orinoco Drainage: AUM 17181, 2, 59.3-60.0 mm SL, caño Maraca, tributary of the caño Igues, Guanare-Guanarito road at road km 60, 8.8275°N, 069.345W, J. W. Armbruster, M. Hardman, J. D. Evans, & J.A. Thomas, 17 Dec 1999. AUM 27728, 3, 67.0- 71.7 mm SL, caño Las Marias, tributary of the río Portuguesa, at town of Quebrada Seca, approximately 45 min. upstream by car from Hwy. 5, 22 km NNW Guanare, J. W.Armbruster & O. León, 28 Feb 1998. AUM 22663, 8 (4 measured), 52.1-94.4 mm SL, caño Mamón, tributary of río Portuguesa, in El Mamón, 24 km E Guanare, 9.07167°N, 069.515°W, J. W.Armbruster, M. Hardman, J. D. Evans, & J. A. Thomas, 2 Jan 2000. AUM 22792, 3 (1 measured), 76.6 mm SL, río Portuguesa, at Hwy 5 bridge, 9.0818°S, 069.68159°W, J. W.Armbruster, M. Hardman, J. D. Evans, & J. A. Thomas, 31 Dec 1999 - 1 Jan 2000. AUM 22833 4 (2 measured), 66.7-80.8 mm SL, same locality and collectors as AUM 17181, 1 Jan 2000. AUM 41708, 4 (0 measured), same locality as AUM 22792, M. H. Sabaj, D. C. Werneke, N. K. Lujan, L. S. de Souza, & O. Leon, 29 Mar 2004. CU 82650, 1, 84.3 mm SL, río Las Marias, río Portuguesa drainage, 9.2000°N, 69.7000°W, P. B. McIntyre et al., 31 Jan 2001. INHS 28650, 1, 105.5 mm SL, río Portuguesa at Mata Larga, D. C. Taphorn, L. M. Page, K. S. Cummings, C. A. Mayer, P. A. Ceas, J. W.Armbruster, C. A. Laird & M. H. Sabaj, 1 Jan 1993. MCZ 59382, 4 (2 measured), 57.4-67.0 mm SL, same locality as AUM 17181, D. C. Taphorn et al., 19 Mar 1983. UF 32331, 1, 76.5 mm SL, río Tucupido just behind the Santuarío de la Coromoto, ca 1.7 km SW of Guanare, just above junction with río Guanare, D. C. Taphorn et al., 26 Mar 1981. UF 80706, 4, 41.1-63.7 mm SL, río Bocono in Puerto Paez, Portuguesa- Barinas border, D. C. Taphorn, C. R. Gilbert, & L. Nico, 10 Apr 1984. Trujillo, río Orinoco drainage: MCNG 27307, 4, 62.6-84.6 mm SL, río Carache, 27 Aug 1990.

Nontypes. Colombia. Meta, río Orinoco drainage: ANSP 128692 , 5 , 41.0- 58.3 mm SL, río Negro , downstream from main Villavicencio- Puerto Lopez highway at La Balsa, W side of river, 29 Feb 1972 . ANSP 131661 , 0, río Negrito , downstream from bridge at La Balsa, río Meta drainage, 22 Mar 1975 . UF 33421 , 1 , 51.0 mm SL, Guacavia River ENE of Villavicencio, 3 Jan 1973 . Venezuela. Amazonas: AUM 39278, 0, río Parucito, río Ventuari Drainage, at raudales Salomon , 2.7 km NE of San Juan de Manapiare, 05.34637°N, 066.03347°W, 16 Apr 2004 . AUM 39849, 0, río Ventuari, beach below Raudales Tencua , 56 km ESE of San Juan de Manapiare, 05.04968°N, 065.62722°W, 19-20 Apr 2004 . MCNG 23846 , 3 , 38.5-43.7 mm SL, island in río Ocamo below Arata rapids, 03°05’S, 64°37’W, 24 Jan 1990 . MCNG 24246 , 5 , 28.7-55.8 mm SL, río Putaco near the confluence of the río Ocamo (river above Chicrita- Pora Rapids), 3 Feb 1990 . MCNG 25802 , 1 , 33.5 mm SL, río Ocamo at Arata Rapids , 03°08’N, 64°34’W, 24 Jan 1990 . UF 77844 , 2 , 49.1-50.5 mm SL, río Ventuari at Tencua just below Tencua Falls , 20 Mar 1981 . Apure, río Orinoco drainage: MCNG 21802 , 1 , 41.8 mm SL, río Cinaruco CORPOVEN camp, 06°31’50"N, 067°26’14"W, 20 Apr 1989 . Bolivar, río Caura drainage: MCNG 21596 , 2 , 43.4-64.4 mm SL, caño Icutú, two turns of the river below Icutú Falls , 05°N, 064°W, 13 Mar 1989 .

Diagnosis. Lasiancistrus tentaculatus is diagnosed by one unique autapomorphy, the presence of small tentacles (tentacules sensu Sabaj et al., 1999) on the snout of nuptial males that are larger than the supporting odontodes. All other Lasiancistrus whose nuptial males have been observed have whiskerlike odontodes at the anterolateral corners of the snout. In addition, L. tentaculatus can be separated from L heteracanthus , L. guacharote , and some L. schomburgkii by having no plates on the abdomen, from L. schomburgkii and L. saetiger by having black spots in the dorsal, caudal, and paired fins fin (vs. no or white spots or entirely gray, respectively), and from L. caucanus by having a forked caudal fin (vs. emarginate).

Description. Morphometrics in Table 3. Largest specimen 147.6 mm SL. Morphometrics in Table 2. Largest specimen 100.1 mm SL. Body strongly dorsoventrally compressed and moderately wide. Head and nape gently sloped to insertion of dorsal fin. Dorsal profile very slightly sloped ventrally to dorsal procurrent caudal-fin spines, then rising slightly to caudal fin. Ventral profile flat to caudal fin. Supraorbital ridge almost absent with interorbital space slightly concave, almost flat. Supraorbital ridge continues as slightly higher, rounded ridge from anterior of orbit to slightly anteroventral of anterior nare. Mesethmoid raised slightly above lateral surface of snout to form slight ridge. Head contours smooth. Eyes small to medium.

Keels absent. All plates slightly convex medially to produce cylindrical body. Mid-dorsal and mid-ventral plate rows incomplete, generally ending below adipose fin; three rows of plates on caudal peduncle. Abdomen naked. First anal-fin pterygiophore not exposed to form platelike structure. 23-25 (mode = 24) plates in median series.

Frontals, infraorbitals, nasals, opercles, pterotics, sphenotics, and supraoccipital supporting odontodes. Opercular odontodes occasionally moderately hypertrophied, thick, and sharp; whiskerlike odontodes rarely present on opercle. Whiskerlike odontodes present in evertible cheek mass and occasionally at anterolateral corner of snout; 1-26 whiskerlike odontodes in evertible cheek mass (mode = 5, N = 29); 12-60 (mode = 36, N = 31) total hypertrophied odontodes in cheek mass. Cheek plates evertible to approximately 90° from head, hypertrophied cheek odontodes folded under opercle when relaxed. Odontodes on tip of pectoral-fin spine slightly hypertrophied. Odontodes on lateral plates not enlarged to form keels.

Dorsal fin not reaching preadipose plate when adpressed; dorsal-fin spine not elongate, edge of dorsal fin straight. Dorsal-fin spinelet V-shaped, dorsal-fin spine lock functional. Dorsal fin II,7 (one of 76 I,6). Adipose fin with one preadipose plate and moderately long spine. Caudal fin slightly emarginate to forked, lower lobe longer than upper, i,14,i (two of 60 i,12,i), with four to five (mode = five, N = 26) dorsal procurrent caudalfin rays and four to five (mode = four, N = 25) ventral procurrent caudal-fin rays. Anal fin short with unbranched ray weak and usually about three quarters length of first branched ray. Anal fin i,5 (one of 76 i,4), Pectoral-fin spine reaching slightly posterior to insertion of pelvic fin when adpressed ventral to pelvic fin. Pectoral fin I,6 (one of 76 I,5). Pelvic fin reaching to posterior of anal-fin when adpressed. Pelvic fin i,5 (N = 78).

Dorsal flap of iris present. Flap between anterior and posterior nares short. Lips wide, fairly thin. Upper lip with small, round papillae. Lower lip with medium-sized papillae anteriorly and smaller ones posteriorly. Maxillary barbels very short, not reaching behind lower lip, occasionally completely adnate. Buccal papilla small. Jaws moderately wide, dentaries forming very oblique angle; premaxillaries forming very shallow arc with an overall angle just slightly less than 180°. Teeth with fairly long, narrow cusps; lateral cusp approximately half-length of medial cusp, stalks of teeth long; 39-88 dentary teeth (mode = 74, N = 23) and 29-89 premaxillary teeth (mode = 67, N = 27).

Color. Body and head almost uniformly brown with slight mottling. Abdomen light tan, ventral surface of caudal peduncle slightly darker. Dorsal, caudal, and paired fins with dark spots centered on fin rays and that may form incomplete or wavy bands. Adipose and anal fins uniformly dark. Lower half of caudal fin generally darker than upper half.

Figures

Fig. 9. Dorsal, lateral, and ventral views of holotype of Lasiancistrus tentaculatus, MCNG 19744, 147.6 mm SL.