GBIF Taxonomic Backbone & Wikipedia Registry Profile
Description. Morphometrics are given in Table 1. Head and body robust but relatively narrow, greatest body depth near dorsal-fin origin. Greatest width of body between opercles and pectoral-fin origins, then narrowing progressively to end of caudal peduncle. Dorsal profile of head and body convex from tip of snout tip to dorsal-fin origin, from there, nearly straight and sloping gradually down to dorsal procurrent caudal-fin rays, then angled dorsally ~ 45 o to caudal fin. Ventral profile convex from tip of snout to below pectoral-fin insertions, abdomen slightly concave to pelvic-fin insertions, from there, straight and sloping gently up towards caudal fin. Caudal peduncle deep and robust. Snout broadly rounded with large broad naked margin in males, less developed in females and juveniles. As in all species of Ancistrus the tentacles are better developed in males (Figure 1) and present in all areas defined by Sabaj et al. (1999): cheek, posterior and anterior margins, anteromedial and posteromedial regions of the unplated snout. Tentacles absent in females, or if present much smaller and only along posterior and anterior snout margins. Eye moderate, dorsal margin of orbit not elevated, interorbital area slightly concave. Hypertrophied cheek odontodes eight to 17 (mode 12), stout with tips hooked anteriorly, strongly evertible, the longest reaching beyond pectoral fin insertion, bases encased in thick fleshy sheaths. Oral disk slightly ovate, wider than long. Lips covered with minute papillae, larger near mouth. Lower lip moderate in size, not reaching pectoral girdle, its border covered with very small papillae. Maxillary barbel short, slightly longer than buccal papilla. Dentary tooth row curved, slightly narrower than premaxillary tooth row. Teeth unevenly bifid, medial cusp much larger and spatulate, lateral cusp minute and pointed, usually not reaching more than half length of medial cusp, but equal in worn teeth. Exposed part of opercle roughly triangular and bearing short stout odontodes. Three to five dermal plates present in postopercular area. Supraoccipital with margins between surrounding bones and plates usually clearly visible. Nuchal plate small and curved posterolaterally. Five series of lateral plates anteriorly, middorsal and mid-ventral plate series end on caudal peduncle. Mid-dorsal plates 10 (1), 14 (2) 15 (8) 16 (17), 17 (19), 18 (17), 19 (2); median plates 21 (5), 22 (38), 23 (23); mid-ventral plates 16 (8), 17 (35), 18 (22), 19 (1); plates bordering dorsal-fin base 6 (39), 7 (26), 8 (1); plates between dorsal and adipose fins 6 (23), 7 (43); preadipose plates: 1 (63), 2 (3). Mid-dorsal and mid-ventral plate series ending at point near vertical through adipose-fin origin. Last plate in median series slightly smaller than penultimate plate, base of caudal fin with about four small platelets after main series, then about eight roughly triangular platelets covering bases of caudal-fin rays. Tiny odontodes present on body plates, largest on posterior margins of plates. All fin spines with small odontodes, more developed in pectoral-fin spine of males. All fin rays with tiny odontodes on rays. Abdomen entirely devoid of plates; no exposed platelets anterior to anal-fin spine. Dorsal-fin origin situated slightly anterior to vertical through pelvic-fin insertion. Dorsal fin short, tip of adpressed fin falling just short of single median preadipose plate. Adipose fin with stout spine and welldeveloped adnate membrane that adheres to plate just anterior to first procurrent caudal-fin ray. Pectoral spine long and slender, extending to middle of pelvic spine. Anal fin well developed, short; first anal-fin pterygiophore covered by skin. Caudal fin with straight oblique posterior margin, spines and first dorsal and ventral rays slightly longer than others, base not visible as plate-like structure. Ventral caudal-fin ray extends posteriorly following horizontal profile of caudal peduncle, not angled downward. Fin-ray formulae (N = 66): dorsal i, 7; pectoral i, 6; pelvic i, 5; anal i, 4; caudal i, 14, i. Caudal procurrent spines: dorsal: 5 (64), 4 (2) ventral: 3 (45), 4 (20), 5 (1). Color in alcohol. Body gray, brown or tan, without dark or light spots; some plates outlined with lighter or darker tones. Ventral portions of head, abdomen and caudal peduncle usually paler, not spotted. The one observed exception is in two specimens from Totoremo, in the middle Tocuyo River drainage, where we observed light spots on the abdomen. In nearby localities of the same tributary no spots were observed. Morphologically these two specimens grouped with A. gymnorhynchus in the PCA analysis. Dorsal fin usually with black pigment at base of first membrane. Caudal fin sometimes very dark gray. A few specimens have numerous inconspicuous pale spots on rays of paired fins upon close inspection. Lips cream color or light gray to whitish.
