Diagnosis: Doumea skeltoni is distinguished from all congeners other than D. chappuisi, D. sanaga, and D. thysi in the number of pectoral-fin rays, being 10, rarely 9 or 11, versus 11 to 13 (Ref. 94772). It differs from D. chappuisi in the predorsal length, 38-45% of standard length vs. 32-37%; the body depth at the dorsal-fin origin, 13-16% of standard length vs. 9-13%; and modal value of the number of vertebrae, mode 35 and range 34-37 vs. mode 37 (Ref. 94772). Doumea skeltoni differs from D. sanaga in the predorsal length, 38-45% of standard length vs. 34-37%; the ratio of caudal-peduncle depth to caudal peduncle length, 12-15% vs. 9-11%; the number of vertebrae, 34-37 vs. 38-41; and nearly completely in the head length, 21-26% of standard length vs. 18-21%; and the body depth at the dorsal-fin origin, 13-16% of standard length vs. 10-13% (Ref. 94772). It differs from D. thysi in the caudal-peduncle length, 23-26% of standard length vs. 19-22%; the caudal-peduncle depth, 3-4% of standard length vs. 5-8; the ratio of the caudal-peduncle depth to caudal-peduncle length, 12-15% vs. 25-40%; and the interorbital width, 27-32% of head length vs. 33-38% (Ref. 94772).

Description: Body elongate and tapering posteriorly (Ref. 94772). Dorsal and ventral profiles of body progressively converge from dorsal-fin origin to posterior terminusof caudal peduncle; greatest body depth located at dorsal-fin origin and greatest body width at anterior limit of pectoral-fin insertion; body smooth skinned; abdominal region transversely flattened (Ref. 94772). Lateral line complete, running along midlateral surface of body, with short, variably spaced and positioned, dorsal and ventral branches extending off main portion of lateral line (Ref. 94772). Caudal peduncle elongate, slender, and dorsoventrally depressed over much of its length, but approximately twice as high as wide at caudal-fin base; least depth of caudal peduncle approximately equal to length of eye (Ref. 94772). Head profile squared off overall in dorsal view with lateral margin slightly convex to straight and snout tip very broadly rounded; head convex dorsally, flat and horizontal ventrally in lateral view; snout convex in lateral view (Ref. 94772). Eye situated entirely within posterior half of head; diameter of eye slightly greater than one-half of interorbital distance; distance from posterior naris to anterior margin of eye equals distance between anterior naris and tip of snout; posterior naris closer to anterior naris than to eye; distance between anterior and posterior nares slightly less than distance of each to contralateral naris (Ref. 94772). Mouth ventral, small, ovoid when open, with broad fleshy tuberculate upper lip and more narrow tuberculate lower lip; barbels short, distally tapered, and tuberculate along ventral surface; maxillary barbel longest, reaching approximately to anterior margin of orbit; inner mandibular barbel shortest, with base situated slightly lateral of midline; outer mandibular barbel arises from angle of mouth and extends posteriorly to tip of maxillary barbel (ref. 94772). Branchiostegal membrane continuous medially, with portion of posterior margin near base of pectoral fin slightly concave; gill slit extends posterodorsally to horizontal through eye; humeral process located above origin of gill opening; suraoccipital process broad and triangular, separated from subdermal nuchal shield by large gap (Ref. 94772). Distal margin of dorsal fin nearly straight, with unbranched ray longest; tip of adpressed dorsal fin extends to vertical through middle of pelvic fin (Ref. 94772). Adipose-fin origin situated above middle of anal-fin base; adipose fin adnate, with posterior limit of fin posterior of vertical through anal-fin base, but not posterior of vertical through tip of adpressed anal fin (Ref. 94772). Pectoral fin large and falcate, with outer ray curved and broad; fin with fleshy pad covering ventral surface (Ref. 94772). Pelvic fin distinctly shorter than pectoral fin; its origin located slightly posterior of vertical through posterior terminus of dorsal-fin base (Ref. 94772). Anal fin small, with distal margin slightly convex (Ref. 94772). Dorsal-fin rays i,6,i or i,7; pectoral-fin rays i,8,i or i,9; pelvic-fin rays i,5; anal-fin rays ii-iii,6,i or ii-iii,7; principal caudal-fin rays i,6,7,i (Ref. 94772).

Colouration: In alcohol, body with scattered brown pigmentation overlying yellowish ground color on dorsal and lateral surfaces of head and body; brown pigmentation absent from ventral surface of head and abdomen, but present on ventral portion of body posterior of pelvic fin; several wide bands of darker regions of pigmentation extend dorsally across midline of body and ventrally to slightly below lateral-line; bands of dark pigmentation approximately equal in anteroposterior expanse to adjacent paler interspaces (Ref. 94772). Head generally darkly pigmented other than for ventral surface and distinctly lighter triangular patch corresponding in position to supraoccipital process; dorsal surface of maxillary barbel dusky, remainder of barbel as well as all surfaces of mental barbels pale (Ref. 94772). Dorsal fin with scattered dark pigmentation along fin rays; pigmentation becoming less concentrated distally; dorsal-fin interradial membranes hyaline (Ref. 94772). Adipose fin with scattered dark pigmentation throughout; pigmentation somewhat less concentrated along distal margin (Ref. 94772). Pectoral and pelvic fins with scattered pigmentation along dorsal surface; pigmentation more concentrated along middle of fin rays and forming dark triangle (Ref. 94772). Anal fin with scattered dark pigmentation along all rays; pigmentation reduced towards distal margin of fin and absent from interradial membranes (Ref. 94772). Caudal fin with dense concentration of dark pigmentation on basal portion of fin and most of distal portions of each lobe; middle portion of caudal fin and narrow distal margin of each lobe pale (Ref. 94772).