|
Dorsal spines (total): 0-0; Dorsal soft rays (total): 16-18; Anal spines: 0-0; Anal soft rays: 16-19. Diagnosis: Nothobranchius itigiensis belongs to the N. ugandensis species group presenting the following combination of characters in males: body colouration light blue with red to red-brown scale margins; frontal part of head red-brown and throat light blue or red; caudal fin uniform red; anal-fin base light blue or yellow with red-brown spotted pattern (Ref. 123150). Nothobranchius itigiensis differs from all other members of the N. ugandensis species group by an anal fin yellow with red-brown spots proximally, that are merged medially to a pattern parallel to fin rays and may be fused distally to form a slender marginal band; caudal peduncle length 14.9-15.7% of standard length vs. 16.1-23.8%, and 96-103% of its depth vs. 111-157%; and head width 68-72% of its depth vs. 73-83% (Ref. 123150).
Description: Medium size Nothobranchius species, maximum recorded size 43.3 mm standard length; general body shape robust, laterally compressed and deep; greatest body depth at vertical in front of pelvic-fin origin, 31.1-33.1% of standard length; greatest body width at pectoral-fin base with body progressively narrowing towards caudal-fin base (Ref. 123150). Dorsal profile slightly convex from tip of snout to base of last dorsal-fin ray, straight on caudal peduncle; ventral profile convex from lower jaw to base of last anal-fin ray, straight on caudal peduncle; caudal peduncle deep, length 96-103% of its depth; anus situated directly in front of anal-fin origin (Ref. 123150). Head moderately long, 30.5-33.4% of standard length, laterally compressed, deeper than wide, head width 68-72% of its depth; snout slightly pointed, smaller than eye diameter; mouth supraterminal, slightly oblique in profile; jaws subequal, lower jaw longer than upper, posterior end of rictus at same level or slightly ventral to centre of eye; premaxilla and dentary with many irregularly distributed conical teeth on inner rows and slightly curved teeth on outer row; eye diameter 28-31% of head length, entirely in anterior half of head, snout to eye end length 43-48% of head length; branchiostegal membrane projecting posteriorly from opercle (Ref. 123150). Dorsal-fin origin anterior to anal-fin origin, both fins originating posterior to mid-length of body, predorsal length 56.1-59.9% of standard length, preanal length 58.0-62.3% of standard length; extremity of dorsal and anal fins rounded, with small contact organs in form of papillae on fin rays and distal margin with short filamentous rays; posterior extremity of dorsal fin reaching caudal-fin base; dorsal fin with 16-18 rays; anal fin with 16-19 rays; pectoral fin subtriangular, insertion slightly posterior to margin of opercular opening, base slightly oblique, upper fin rays positioned slightly anteriorly to lower fin rays, its tip reaching or slightly overlapping base of pelvic fin; pelvic fin subabdominal, origin at about mid-length of body, short, base medially separated, tips reaching urogenital papilla; caudal fin subtruncate, with 19-22 branched rays, plus 3 or 4 dorsal and ventral procurrent rays (Ref. 123150). Scales cycloid, body and head entirely scaled, except for ventral surface of head; no scales on base of dorsal and anal fins; scales in mid-longitudinal series 29-33 plus two or three small scales on caudal-fin base; transverse rows of scales in front of dorsal-fin origin 12; scale rows around caudal peduncle 12-14 (Ref. 123150). Cephalic squamation pattern variable; frontal neuromasts separate in two rows of shallow grooves behind the upper lip, with one neuromast in each groove; cephalic sensory system at supraorbital level undivided in a long continuous shaloow groove with eight exposed neuromasts; at supratemporal level with five exposed neuromasts in undivided, curved deep groove; preorbital canal in shallow groove with six to eight exposed neuromasts; infraorbital level with series of about 12 exposed neuromasts or small buttons and ventral and posterior margin of orbit, as a continuous part of preorbital canal; postorbital canal in deep groove with one exposed neuromast; preopercular system with exposed neuromasts in deep groove on preopercle portion; in shallow groove with exposed neuromasts and small buttons on ventral portion; mandibular canal in shallow groove with about six small neuromasts; one neuromast on each scale along trunk mid-longitudinal series (Ref. 123150).
Colouration: Colouration of live male: scales on trunk and head light iridescent blue with red-brown margins, forming regular reticulation pattern; scales on abdomen faint blue with less pronounced margins; scales on dorsum anterior to dorsal fin with wider margins and red-brown conferring an overall darker appearance towards the head; snout and frontal portions of head red-brown; throat light blue; posterior scale margins on post-orbital portion of opercle forming two to three red-brown oblique bars; iris light blue to golden; exposed branchiostegal membrane cream; dorsal fin light blue or yellow with irregular red-brown spots proximally that may merge to a red-brown striped pattern perpendicular to fin rays in medial and distal zones; anal fin yellow with red-brown spots proximally, merged medially to a pattern parallel to fin rays and might be fused distally to form red-brown marginal band; caudal fin uniform red; in some specimens with irregular lighter red distal band; pelvic fin light blue proximally and yellow with red brown dots distally; pectoral fins hyaline with narrow light blue distal margin (Ref. 123150). Colouration of live female: trunk and head light grey-brown, darker on dorsum and lighter ventrally; scales with a very narrow grey margin; scale centres iridescent silver to very pale green or blue-green; all fins hyaline; iris golden (Ref. 123150). |