| Diagnosis: |
Dorsal spines (total): 0-0; Dorsal soft rays (total): 15-18; Anal spines: 0-0; Anal soft rays: 16-18. Diagnosis: Nothobranchius albertinensis is distinguished from all other species of the genus, with the exception of N. ugandensis, by the following combination of characters in males: body colouration light blue with red-brown scale margins; frontal part of head and snout red-brown and throat light blue; caudal fin uniform red (Ref. 123150). Furthermore, it differs from N. ugandensis by a yellow dorsal fin with red-brown stripes in medial part parallel to fin rays vs. light blue with red-brown spots and irregular stripes perpendicular to fin rays; yellow anal fin without markings vs. light blue and occasionally with red-brown spots; anal fin positioned anterior to dorsal fin, mean preanal length 59.8% of standard length and mean predorsal length 60.7% of standard length vs. posteriorly positioned with 60.9% of standard length and 60.2% respectively in N. ugandensis; and greater anal-fin base length, 22.5-25.9% of standard length vs. 19.3-22.2% (Ref. 123150).
Description: Medium size Nothobranchius species; general body shape robust, laterally compressed and deep; greatest body depth at vertical in front of pelvic-fin origin, 29.6-34.8% of standard length; greatest body width at pectoral-fin base with body progressively narrowing towards caudal-fin base (Ref. 123150). Dorsal profile slightly concave from tip of snout to nape and convex from nape to base of last dorsal-fin ray, straight to slightly concave on caudal peduncle; ventral profile convex from lower jaw to base of last anal-fin ray, straight to slightly concave on caudal peduncle; caudal peduncle relatively deep, length 130-138% of its depth; anus situated directly in front of anal-fin origin (Ref. 123150). Head moderately long, 26.4-33.2% of standard length, laterally compressed, deeper than wide, head width 78-82% 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 25-31% of head length, entirely in anterior half of head, postorbital length51-58% of head length; branchiostegal membrane projecting posteriorly from opercle (Ref. 123150). Dorsal-fin origin posterior to anal-fin origin, both fins originating posterior to mid-length of body, predorsal length 58.2-64.3% of standard length and preanal length 56.8-63.5% 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 15-18 rays and anal fin with 16-18 rays; pectoral fin subtriangular, insertion slightly posterior to margin of opercular opening, base slightly oblique, upper fin rays positioned slightly anterior 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, its tip reaching urogenital papilla; caudal fin subtruncate, with 17-20 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 27-31 plus two or three small scales on caudal-fin base; transverse rows of scales in front of dorsal-fin origin 11-12; scale rows around caudal peduncle 12-14 (Ref. 1123150). 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 fragmented in two discontinuous shallow grooves with two exposed neuromasts in each, whereas at supratemporal level with four exposed neuromasts in undivided, slightly curved shallow groove; preorbital canal in deep groove with four exposed neuromasts; infraorbital level with series of about 20 small buttons at ventral and posterior margin of orbit; postorbital canal in deep groove with one exposed neuromast; preopercular system with exposed neuromasts in deep groove on preopercle portion, whereas in shallow groove with exposed neuromasts and small buttons on ventral portion; mandibular canal in shallow groove with about ten 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 a regular reticulation pattern, occasionally forming oblique bars; scales on abdomen faint blue with less pronounced margins; scales on dorsum anterior to dorsal fin with wider margins conferring an overall darker appearance; lower jaw, 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 golden; exposed branchiostegal membrane light blue; dorsal fin yellow with red-brown spots proximally, with red-brown stripes parallel to fin rays in the medial and distal zones, and with dark grey fin tips; anal fin yellow, without markings, and with narrow dark grey distal margin on fin tips; caudal fin uniform red and occasionally with a narrow or slender dark grey distal margin; pelvic fin hyaline proximally and light blue medially and distally; pectoral fin hyaline with narrow light blue distal band (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 blue; all fins hyaline; iris golden (Ref. 123150). |