Dolichancistrus atratoensis ( Dahl, 1960 )

Ballen, Gustavo A. & Vari, Richard P., 2012, Review of the Andean armored catfishes of the genus Dolichancistrus Isbrücker (Siluriformes: Loricariidae), Neotropical Ichthyology 10 (3), pp. 499-518 : 504-506

Dolichancistrus atratoensis ( Dahl, 1960)

Fig. 1

Pseudancistrus atratoensis Dahl, 1960: 455 , figs. [Type locality: Colombia, Quebrada La Noche , tributary to upper río Atrato, approximate height above sea level 550 m].

Dolichancistrus atratoensis Isbrücker, 1980: 47 [shift to Dolichancistrus ]. - Burgess, 1989: 434 [in listing of species of the Loricariidae ].- Isbrücker, 2001: 26 [in listing of species of the Loricariidae ].- Isbrücker, 2002: 29 [in listing of species of the Loricariidae ]. - Fisch-Muller, 2003: 384 [in checklist of species of the Ancistrinae ]. - Maldonado-Ocampo et al., 2005: 153, map 143 [Andes of Colombia, upper río Atrato; summary data; common name]. - Maldonado-Ocampo et al. 2006: 149 [ Colombia, río Atrato; misidentified in part]. - Ferraris, 2007: 235 [in checklist of catfishes]. - Maldonado-Ocampo et al., 2008: 198 [ Colombia].

Pseudancistrus atratoensis, Cala, 1981: 3 [type depository]. - Mojica & Castellanos-C, 2007: 84 [type repository; type locality erroneously cited as in Município Riosucio, Departamento de Antioquia, see Remarks].

Material examined. All collections from Colombia. CIUA 768 , 1, 120.3 mm SL, Departamento de Antioquia, río Atrato drainage, Urrao, vereda Calles, Quebrada La Selva, 1365 masl. CIUA 769 , 2 , 92.9-111.6 mm SL, Departamento de Antioquia, río Atrato drainage, Urrao, vereda Calles, quebrada La Crespa, 1346 masl, 6°31’10”N, 76°17’05.1”W. CIUA 771 , 1, 114.6 mm SL, Departamento de Antioquia, río Atrato drainage, Frontino , vereda Venados , río Venados , 824 masl, 6°32’22.5”N, 76°19’33.9”W. CIUA 772 , 2 , 51.0-70.0 mm SL, Departamento de Antioquia, río Atrato drainage, Frontino , vereda Venados , quebrada La Aguada , 1110 masl, 6°33’26.4”N 76°17’03.8”W. IAvH-P 6630 , 1 , 63.9 mm SL, Departamento de Chocó , Quibdó, río Tutunendo. ICNMHN 51 , holotype, 81.0 mm SL, male, Departamento de Chocó , Carmen de Atrato , río Atrato , quebrada La Noche, 500 masl. ICNMHN 46 , paratypes, 42, 42.0- 68.6 mm SL; erroneously cited as ICNMHN 48 by Maldonado-Ocampo et al. (2008), Departamento de Chocó , Carmen de Atrato , río Atrato , Quebradas La Noche and La 16. ICNMHN 74 , paratype, 1, 61.1 mm SL, male, Departamento de Chocó , Carmen de Atrato , río Atrato , Quebradas La Noche and La 16. ICNMHN 3460 , 1 , 50.9 mm SL, Departamento de Chocó , Pacific Ocean versant, Purrichá, río Cubarradó , quebrada Purrichá.

Diagnosis. Dolichancistrus atratoensis is diagnosable from all congeners in having a unique form of the cheek plates in which the anterior plate is smaller than the posterior plate and has the form of a ventrally oriented triangle from a lateral view (vs. anterior and posterior cheek plates of nearly the same size and square or rectangular from a lateral view, respectively), in having the tip of the adpressed pectoral-fin spine in mature males falling within the area between the base and middle of the adpressed pelvic-fin spine (vs. reaching to the tip of the pelvic-fin spine in D. carnegiei , falling slightly short of, to extending somewhat beyond, the tip of the spine in D. cobrensis , and far surpassing the tip of the spine in D. fuesslii ). Dolichancistrus atratoensis is additionally distinguished from D. carnegiei in the length of the anal-fin spine (one-third or less vs. one-half or more of the length of the pelvic-fin spine, respectively). Dolichancistrus atratoensis further differs from D. cobrensis in the condition of the buccal papilla within the oral cavity at the limit of the symphysis of the premaxillae (present vs. absent, respectively). Dolichancistrus atratoensis can also be differentiated from D. fuesslii in the form of the distal margin of the pelvic fin in mature males (either straight or approximately smoothly convex vs. Wshaped, respectively) and in the relationship of the posterior cheek plate with the exposed portion of the opercle (ossifications distinctly separated vs. the margin of the anteromedial corner of the posterior cheek plate in contact with the anterior margin of the exposed portion of the opercle, respectively).

Description. See description under generic account for features common to all species of Dolichancistrus . Largest examined specimen 120.3 mm SL. Morphometrics presented in Table 1 . Dorsal-fin rays ii,8; anal-fin rays ii,3 or 4 [one malformed individual with ii,1]; caudal-fin rays i,14,i; pectoral-fin rays i,6; pelvic-fin rays i,5. Preadipose plates 1-2; median plates 22-25. Buccal papilla present within oral cavity at limit of symphysis of premaxillae. Enlarged odontodes variably present along entire anterior or anterolateral margins of snout (see Sexual dimorphism for comments on variation). Anterior margin of posterior cheek plate distinctly separated from anterior margin of exposed portion of opercle.Anterior cheek plate triangular, obliquely oriented, approximately one-half length of, and positioned largely ventrolateral to, posterior cheek plate. Hypertrophied cheek odontodes distally recurved. Distal margin of pelvic fin straight to convex. Spine of adpressed pectoral fin in mature males reaching posteriorly approximately midway along length of adpressed pelvic fin and in mature females approximately to insertion of pelvic fin. Odontodes extending along distal one-half of pectoral-fin spine. Anal fin usually present, but highly reduced in the male and absent in the female of CIUA 772.

Coloration in alcohol. Overall ground coloration of head and body brownish on lateral and dorsal surfaces, lightly pigmented ventrally other than for upper lip. Body pigmentation pattern variable and ranging from unpatterned to highly vermiculated and mottled, sometimes with unpigmented region on ventral portion of caudal peduncle. Variation in color pattern apparently not correlated with age, sex, or breeding condition. Largest examined individual with nearly uniform dark gray coloration over head and body. Dorsal fin with alternating dark and light areas along rays that form irregular, somewhat transverse bar-like pattern along length of fin. Spacing between dark areas variable, but usually of same expanse as width of dark regions. Membranes lack dark pigmentation. Anal fin with scattered chromatophores covering basal portion of fin rays, but with membranes unpigmented. Caudal fin with alternating dark and light areas along rays that form irregular transverse bar-like pattern across vertical extent of fin. Pectoral-fin spine with alternating dark and light regions on dorsal surface; ventral surface lacking dark pigmentation. Pectoral and pelvic fins with pattern of alternating transverse dark and light pigmentation on lateral rays, with medial rays and all of membranes unpigmented.

Sexual dimorphism. Mature males of Dolichancistrus atratoensis demonstrate greater degrees of development of the odontodes along the margin of the snout, the medial region of head from the tip of the snout to nares and in the area between the orbit and nares than do mature females. The pectoral-fin spine of mature males is proportionally longer than that of mature females.

Distribution. Dolichancistrus atratoensis is known from southeastern tributaries of the río Atrato in northern Colombia along with the río Cubarradó, a small Pacific versant system draining a portion of the southern slope of the Serranía de Baudó in western Colombia ( Fig. 2 ).

Common name. Cacucho, Guacuco ( Maldonado-Ocampo et al., 2005: 153).

Remarks. Dahl (1960) identified the holotype of Pseudancistrus atratoensis as a female and the allotype (= paratype) as a male. Examination revealed that both are males with the holotype lacking hypertrophied odontodes despite having an obvious male genital papilla and the elongate pectoral spine characteristic of male congeners. Presumably Dahl’s identification of the holotype as a female was based on the absence of hypertrophied odontodes in females of some ancistrin species. As noted above, these odontodes are seasonally absent in males of Dolichancistrus .

Dahl (1960: 455) reported the type locality of Pseudancistrus atratoensis as “quebrada La Noche, tributary to the upper Atrato, approximate height above sea level 550 m ” and that the types were collected on “ August 10 th, 1959.” In a compendium of ICNMHN fish types, Mojica & Castellanos-C (2007: 84), modified this to “ Departamento de Antioquia, Riosucio, alto río Atrato, quebrada La Noche, vertiente occidental, Cordillera Occidental, altitud 550 m ” thereby shifting the locality to a different department. ICNMHN catalog cards indicate Dahl collected at Quibdó in the Departmento de Chocó on 5 and 14 August, at El Carmen de Atrato on August 8, and quebrada La Noche on 7-10 August. All these localities are distant from Riosucio, which is clearly an incorrect emendation. One of the two lots (IAvH-P 6629) cited as Dolichancistrus atratoensis by Maldonado-Ocampo et al. (2006) is instead a species of Leptoancistrus .

Figures

Fig. 1. Dolichancistrus atratoensis, CIUA 768, 120.3 mm SL. Colombia, Departamento deAntioquia, quebrada la Selva; dorsal, lateral and ventral views.

Fig. 2. Map of Colombia showing localities for the species of Dolichancistrus. Dotted contours represent 1000 masl isoclines and striped areas indicate regions above 3000 masl. Some symbols represent more than one locality and/or lot of specimens. Dolichancistrus atratoensis (triangles; type locality = 1); D. carnegiei (squares; type locality = 2); D. cobrensis (circles; type locality = 3); D. fuesslii (inverted triangles; type locality = 4). Base map provided by John D. Lynch.