Pseudancistrus kayabi Silva, Roxo & Oliveira 2015

Morphometric data is presented in Table 1. In lateral view, dorsal profile convex from snout tip to dorsal-fin origin; straight, gradually descending from dorsal-fin origin to posterior insertion of adipose fin; straight, steeply ascending to insertion of caudal-fin; ventral profile flat from snout tip to anal-fin origin; shallowly concave from anal-fin insertion to lower caudal-fin spine; greatest body depth at dorsal-fin origin. In dorsal view, greatest body width across cleithral region; snout broadly elliptical; body progressively narrow from opercular region to caudal fin. Cross-section of body between pectoral and pelvic fins rounded dorsally and flattened ventrally; cross-section of caudal peduncle ellipsoid. Body almost entirely covered with plates except on ventral portions of head, abdomen, and dorsal-fin base. Five lateral rows of dermal plates, dorsal plates 21−22, lateral mid-dorsal plates 21−22, lateral median plates 22−23, lateral mid-ventral plates 21−22, lateral ventral plates 19−20. Three predorsal plates; eight plates below dorsal-fin base; four plates between dorsal fin and adipose fin; five rows of plates on caudal peduncle. Dorsal spinelet present. Morphometric data for Pseudancistrus kayabi and Pseudancistrus asurini. SD = standard deviation. Pseudancistrus kayabi n = 21 Pseudancistrus asurini n = 21 Holotype Range Mean SD Holotype Range Mean SD SL 88.4 61.5−87.7 78.5 7.2 195.8 195.8−45.9 85.9 37.9 Percentage of SL Predorsal length 42.7 39.4−48.5 43.8 1.9 39.5 39.1−42.7 40.9 1.2 Head length 34.6 30.2−40.2 34.9 1.9 33.6 31.9−35.8 33.9 0.9 Head-dorsal length 8.0 7.1−11.0 9.3 1.0 7.5 5.3−8.2 6.9 0.7 Cleithral width 33.4 31.2−38.6 33.5 1.7 35.8 30.9−35.8 32.8 1.4 Head-pectoral length 29.1 24.5−33.6 29.6 2.0 31.7 21.9−31.7 28.3 1.8 Thorax length 22.8 19.6−25.6 22.2 1.6 20.1 20.1−25.5 22.7 1.5 Pectoral spine length 30.0 22.3−29.7 27.7 1.7 36.2 27.8−36.7 31.6 2.5 Abdominal length 24.2 20.3−30.4 24.3 2.2 20.5 20.5−26.0 23.9 1.4 Pelvic spine length 25.9 20.3−29.8 23.7 2.0 27.0 23.8−27.4 25.9 1.0 Postanal length 32.3 25.9−35.9 31.3 2.5 29.2 29.2−35.3 32.8 1.6 Anal-fin spine length 9.6 5.4−12.9 10.1 1.7 16.6 7.8−16.6 10.1 1.9 Dorsal-pectoral depth 26.4 20.2−29.4 25.9 1.9 24.0 23.3−26.5 24.8 0.9 Dorsal spine length 24.3 17.7−29.2 23.0 2.1 22.5 22.5−32.7 20.0 2.2 Dorsal-pelvic depth 22.4 15.2−26.7 21.2 2.3 19.3 17.2−26.5 20.1 2.0 Dorsal-fin base length 28.1 20.4−28.1 26.0 1.7 29.9 24.9−30.6 27.4 1.6 Dorsal-adipose distance 14.3 9.0−14.3 12.0 1.9 13.3 13.1−17.4 15.4 1.2 Adipose-spine length 10.1 6.3−16.9 9.1 2.4 8.6 7.7−10.3 8.6 0.6 Dorsal adipose-caudal distance 16.0 13.4−22.0 16.3 2.3 12.1 12.1−16.5 15.0 1.0 Caudal peduncle depth 11.3 10.0−16.7 11.0 1.5 10.6 9.1−11.0 10.2 0.5 Ventral adipose-caudal distance 22.6 20.3−25.6 22.2 1.2 19.5 19.5−22.9 21.3 1.0 Adipose-anal distance 18.9 16.9−24.8 19.6 1.9 18.8 16.9−19.9 18.8 0.8 Dorsal-anal distance 33.1 29.3−35.4 32.8 1.4 12.6 12.1−19.1 13.3 1.5 Pelvic-dorsal distance 27.6 17.4−27.6 21.1 1.8 28.2 18.3−29.4 25.7 2.7 Percentage of HL Head-eye length 26.4 25.8−31.4 28.8 1.5 27.7 25.9−33.1 29.2 1.8 Orbital diameter 13.8 12.7−20.3 15.5 1.7 13.1 13.1−19.9 16.8 1.7 Snout length 67.4 62.3−69.3 65.4 1.6 69.5 56.6−72.4 62.2 4.5 Internares width 14.8 13.2−18.7 15.8 1.3 15.5 11.9−16.3 14.5 1.2 Minimal interorbital distance 30.6 27.4−35.7 29.1 1.9 31.9 24.0−32.6 28.2 2.4 Mouth length 48.8 48.8−62.3 57.5 2.5 49.7 39.8−51.9 45.9 3.5 Barbel length 10.9 4.2−10.9 8.0 1.6 5.5 4.6−8.7 7.2 1.3 Dentary tooth cup length 20.8 15.4−24.6 20.5 2.6 20.1 16.1−22.4 19.8 1.7 Premaxillary tooth cup length 19.5 16.5−25.6 19.5 2.2 18.1 17.8−24.3 20.5 1.9 Head depth 64.2 59.7−65.7 62.4 1.8 64.3 56.6−66.2 62.6 2.4 Body plates and cleithrum with minute odontodes. Odontodes slightly hypertrophied on pectoral-fin spines, gradually larger towards tips. Numerous yellowish hypertrophied odontodes along lateral margins of head including snout; odontodes small on tip of snout increasing gradually in length from anterolateral margin of snout to cheeks; longest odontodes on posteriormost portion of non-evertible cheek plates. Eye small (orbital diameter 13−20% HL), dorsolaterally positioned. Oral disk transversely ellipsoid. Lower lip not reaching transverse line between gill openings. Lower lip covered with numerous small papillae. Maxillary barbel developed. Mouth relatively large. Premaxillary teeth 33−70 per ramus; dentary teeth 39−74 per ramus. Teeth bifid, medial cusp large and rounded, lateral cusp minute and rounded. Jaws wide, dentaries forming oblique angle, premaxillaries almost co-linear. Dorsal fin I,7, origin approximately at midpoint between pectoral- and pelvic-fin origins, last dorsal-fin ray reaching adipose fin when depressed. Pectoral fin I,6, spine tip slightly curved inward, covered with enlarged odontodes distally; depressed tip reaching one-third length of pelvic-fin spine. Pelvic fin I,5, spine tip curved inward, almost reaching anal-fin origin when depressed. Anal fin I,5, spine tip straight, reaching sixth plate posterior to its origin. Caudal fin I,7-7I, distal margin concave, inferior lobe longer than superior. Adipose fin with straight spine, preceded by single median preadipose plate.

Pseudancistrus kayabi is known from the rio Teles Pires, rio Tapajós basin, municipality of Itaúba and Paranaíta, Mato Grosso State, Brazil (Fig. 2a).