Lasiancistrus caucanus Eigenmann, 1912

Poveda-Cuellar, José Luis, Conde-Saldaña, Cristhian Camilo, Villa-Navarro, Francisco Antonio, Lujan, Nathan K. & Santos, Jorge Abdala Dergam dos, 2023, Phylogenetic revision of whisker-cheeked suckermouth catfishes (Loricariidae: Lasiancistrus) from east of the Andes: five species where once there were two, Zoological Journal of the Linnean Society 199 (3), pp. 688-712 : 699-703

Lasiancistrus caucanus Eigenmann, 1912

( Fig. 4 ; Tables 4 and 5 )

Lasiancistrus caucanus Eigenmann, 1912: 11 [type locality: La Vieja River , Cauca River drainage, Cartago, Colombia; holotype: FMNH 56034 , length 133.7 mm standard length (SL)]. Holotype illustrated by Eigenmann (1922: 76, pl. 11).

Diagnosis: Lasiancistrus caucanus differs from all other trans-Andean species of Lasiancistrus except L. guacharote by having a suture between the parieto-supraoccipital and compound pterotic straight (vs. slightly concave; Fig. 5 ), and from L. guacharote by lacking abdominal plates (vs. abdomen with patch of plates medial to pectoral-fin spine insertion). Moreover, L. caucanus differs from L. mayoloi by having the head with a brown reticulated colour paưern (vs. head covered by small light brown spots) and the snout more rounded (vs. more acute; Fig. 5 ), from L. volcanensis by having the dorsal rim of the orbit slightly above the interorbital space (vs. dorsal rim of orbit level with interorbital space), abdominal region pyriform (vs. rectangular; Fig. 6 ) and seven ribs, (vs. eight); from L. wiwa by having the parieto-supraoccipital posteromedially projected (vs. not posteromedially projected; Fig. 5 ) and the posterior margin of the urohyal rounded (vs. V-shaped; Fig. 7 ).

Description: Morphometrics are presented in Table 4 , meristics in Table 5 . Abdomen naked. Body broadest anteriorly, narrow (depressed), with greatest body width at cleithrum. Dorsal profile gently ascending from snout to supraoccipital, flat to dorsal-fin origin, gently descending in a straight line to dorsal procurrent caudal-fin rays, then slightly ascending to dorsal caudal-fin insertion. Body depth greatest at dorsal-fin origin. Ventral profile flat from snout to ventral caudal-fin insertion. Robust caudal peduncle almost triangular in cross-section: flaưened ventrally, with flaưened flanks converging to more acute dorsum.

Twenty-four median plates (mode = 24); three predorsal plates; six plates along dorsal-fin base; seven plates between dorsal and adipose fins; five plates between adipose and caudal fins; 10 or 11 plates between anal and caudal fins (mode = 10); three horizontal series of lateral plates on caudal peduncle. Parieto-supraoccipital level with nuchal region. Nuchal plate small and curved posterolaterally. Snout slightly rounded. Eye small (orbit diameter 17.5 ± 1.7% of head length), with dorsal rimoforbitslightlyelevatedaboveinterorbitalspace.Interorbital space flat. Iris operculum present. Frontals, infraorbital, nasals, opercles, pterotics, sphenotics and supraoccipital supporting odontodes. Cheek odontodes robust, sharp (mode = 13, N = 51).

Whisker-like odontodes present in evertible cheek mass and in some individuals at anterolateral corner of snout and oriented ~90° from head. Distal pectoral-fin spine odontodes slightly hypertrophied. Odontodes on lateral plates not enlarged to form keels. Lips covered with minute hemispherical papillae; papillae larger near mouth. Lower lip wide, reaching almost to pectoral girdle; upper lip narrower. Maxillary barbel short, not reaching gill opening. Teeth bicuspid; 25–80 less dentary teeth (mode = 52); 26–61 less premaxillary teeth (mode = 47).

Dorsal-fin origin situated slightly anterior to vertical through pelvic-fin insertion. Dorsal-fin spine shorter than snout length; last dorsal-fin ray reaching third preadipose plate when depressed. Adipose-fin spine curved, stout, not embedded; membrane present, easily visible beneath spine. Pectoral-fin spine reaching almost one-third pelvic-fin length when adpressed; some large specimens with pectoral-fin spine reaching middle of pelvic fin. Pelvic-fin spine reaching to origin or middle of anal fin when adpressed. Unbranched anal-fin ray slightly shorter than first branched ray. Caudal fin slightly forked; ventral lobe longer than dorsal. Tiny odontodes present on body plates and all fin spines and rays. Dorsal fin i (one dorsal-fin spine),7 (seven dorsal-fin rays); caudal fin i,14,i; pectoral fin i,6; pelvic fin i,5; anal fin i,5. Twenty-six vertebrae (N = 4). Seven ribs (N = 4).

Coloration in life: Body and head with light brown base colour and darker brown wavy stripes or reticulations on head and four darker brown dorsolateral stripes on body. Abdomen uniformly light brown. All fins with darker brown bands. Adipose fin uniformly light brown.

Coloration in alcohol: As in life but faded, with less distinctive paưerns.

Distribution: Lasiancistrus caucanus is distributed in drainages throughout the upper Cauca River basin, Colombia ( Fig. 1 ).

Comments: Lasiancistrus caucanus was originally described from the upper Cauca River (Cartago); however, the taxonomic revision by Armbruster (2005) redefined the species range to include that previously associated with L. mayoloi (originally described from the San Juan River basin), L. volcanensis (originally described from the middle Magdalena River basin) and L. planiceps (originally described from the Tuyra River basin), all of which were hypothesized by Armbruster to be junior synonyms. Here, we restrict L. caucanus to the Upper Cauca River basin, removing the resurrected L. mayoloi and L. volcanensis , but retaining L. planiceps as a junior synonym of L. mayoloi . In addition to diagnostic characters mentioned above, interspecific COI genetic distances were> 3.1% between L. caucanus and all congeners.

Material examined: All Colombia, upper Cauca River, Valle del Cauca department: CZUTIC 12434 (c&s), 19 individuals, 20.8–98.8 mm SL, La Vieja River , 4°32 ʹ 45.4 ″ N, 75°52 ʹ 14.8 ″ W; CZUTIC 12467, nine, 24.9–96.6 mm SL, La Vieja River , 4°32 ʹ 45.4 ″ N, 75°52 ʹ 14.8 ″ W; CZUTIC 13847, five, 32.4–59.7 mm SL, Hato River , no coordinates; CZUTIC 13853, five, 37.1–98.6 mm SL, Mandiua River , no coordinates; CZUTIC 18267, six, 31.3–67.4 mm SL, Melendez River , 3°23 ʹ 21.5 ″ N, 76°30 ʹ 56.8 ″ W; CZUTIC 18344, four, 17.9–58.4 mm SL, Mediacanoa River , 3°53 ʹ 43.0 ″ N, 76°22 ʹ 01.2 ″ W; CZUTIC 18355, three, 61.2–82.1 mm SL, Mediacanoa River , 3°53 ʹ 43.0 ″ N, 76°22 ʹ 01.2 ″ W; FMNH 56034 (ph), one, 133.7 mm SL, holotype, La Vieja River ; MCZ 35871 (ph), one, 44.5 mm SL, Frío River , 5°41 ʹ 36.6 ″ N, 75°46 ʹ 14.9 ″ W; ROM 106929, seven, 18.9–75.8 mm SL, Mediacanoa River at community of Mediacanoa , 3.89536, −76.36697; ROM 106915, 477– 52 mm SL, Rio Mediacanoa River at finca Los Chorros .

Figures

Figure 1. Geographical distributions of trans-Andean species of Lasiancistrus individuals and species examined in this study. Key:purple stars, Lasiancistrus caucanus; orange triangles, Lasiancistrus guacharote; green circles, Lasiancistrus mayoloi; red diamonds, Lasiancistrus volcanensis; yellow squares, Lasiancistrus wiwa.

Figure 4. Lasiancistrus caucanus Eigenmann, 1912. CZUTIC 17449, 58.48 mm standard length, from Río Mediacanoa, Upper Cauca basin. Scale bar: 10 mm. Photographs by N. K. Lujan.

Figure 5. Dorsal view of anterior portion of body.A, Lasiancistrus caucanus, CZUTIC12434, 98.83 mm standard length (SL). B, Lasiancistrus volcanensis, CZUTIC5898, 83.59 mm SL. C, Lasiancistrus mayoloi, CZUTIC21345, 91.68 mm SL.D, Lasiancistrus wiwa, CZUTIC17449, 79.55 mm SL. Abbreviations: F, frontal; PT, compound pterotic; SO, parieto-supraoccipital; SP, sphenotic. Scale bars:10 mm.

Figure 6. Ventral view of abdominal region.A, Lasiancistrus caucanus, CZUT-IC 12434, 98.83 mm standard length (SL). B, Lasiancistrus volcanensis, CZUT-IC 5898, 83.59 mm SL.C, Lasiancistrus mayoloi, CZUT-IC 21345, 91.68 mm SL. D, Lasiancistrus wiwa, CZUT-IC 17449, 79.55 mm SL. Scale bars: 1 mm.

Figure 7. Urohyal (UH) and hypohyals (HH) in ventral view. A, Lasiancistrus wiwa, CZUTIC17449, 79.55 mm standard length (SL). B, Lasiancistrus caucanus, CZUTIC12434, 98.83 mm SL. C, Lasiancistrus volcanensis, CZUTIC5898, 83.59 mm SL. D, Lasiancistrus mayoloi, CZUTIC21345, 91.68 mm SL. Scale bar: 1 mm.