Nothobranchius moameensis Nagy, Watters & Bellstedt, 2020

Family:  Nothobranchiidae (African rivulines)
Max. size:  4.34 cm SL (male/unsexed)
Environment:  benthopelagic; freshwater; pH range: 7.4 - 9.3,
Distribution:  Africa: ephemeral pools and marshes of Moame and other smaller river systems south of Lake Victoria in northern Tanzania (Ref. 123150).
Diagnosis:  Dorsal spines (total): 0-0; Dorsal soft rays (total): 15-19; Anal spines: 0-0; Anal soft rays: 16-19. Diagnosis: Nothobranchius moameensis 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; and anal fin light blue or yellow with red-brown spotted pattern (Ref. 123150). Nothobranchius moameensis differs from all other members of the N. ugandensis species group by a light blue anal fin with red-brown dots proximally and medially, and with light blue or yellow distal zone without markings; interorbital width 52-59% of head length vs. 38-51%; and caudal peduncle length 111-121% of its depth vs. 96-103% or 122-157% (Ref. 123150). Furthermore, it differs from N. attenboroughi by a greater body depth, 31.6-33.2% of standard length vs. 25.7-31.0%; a greater head depth, 87.1-94.3% of head length vs. 80.1-86.2%; and a dorsal fin positioned anterior to the anal fin, preanal length mean 62.2% of standard length and predorsal length mean 60.9% of standard length vs. posteriorly positioned with mean values of 59.8% of standard length and 60.6% of standard length, respectively, in N. attenboroughi (Ref. 123150). Description: Medium size Nothobranchius species, maximum recorded size 43.4 mm standard length; general body shape robust, laterally compressed and deep; greatest body depth at vertical in front of pelvic-fin origin, 31.6-33.2% 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 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 deep, length 110-121% of its depth; anus situated directly in front of anal-fin origin (Ref. 123150). Head moderately long, 26.1-30.1% of standard length, laterally compressed, deeper than wide, head width 73-78% 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 30-34% of head length, mainly in anterior half of head, snout to eye end length 47-53% 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 57.9-62.3% of standard length, preanal length 59.8-63.8% 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 15-19 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, its tip reaching urogenital papilla; caudal fin subtruncate, with 17-19 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 28-33 plus two or three small scales on caudal-fin base; transverse rows of scales in front of dorsal-fin origin 12-13; scale rows around caudal peduncle 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 shallow groove with four exposed neuromasts; at supratemporal level with four to six exposed neuromasts in undivided, curved deep groove; preorbital canal in shallow groove with three or four exposed neuromasts; infraorbital level with series of about 12 small buttons at ventral and posterior margin of orbit; postorbital canal in deep groove with one or two exposed neuromasts; preopercular system with exposed neuromasts in deep groove on preopercular 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 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 and red-brown conferring overall darker appearance towards head; frontal portions of head red-brown; lips light blue; 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 white to light blue; dorsal-fin base light blue, almost completely covered by pattern of irregular red-brown patches proximally and wide red-brown stripes parallel to fin rays medially and distally; anal fin light blue with red-brown spots proximally and medially; some specimens with light blue or yellow distal zone without markings; caudal fin uniform red; pelvic fin light blue with red brown dots in proximal and medial zones; pectoral fin 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 pale blue; all fins hyaline; iris golden (Ref. 123150).
Biology:  Found in an ephemeral pool, circular with a diameter of about 10 m, and less than a meter at the deepest point; in turbid water and the bottom of the pool not visible (Ref. 123150).
IUCN Red List Status: Endangered (EN); Date assessed: 18 May 2020 (B1ab(iii)+2ab(iii)) Ref. (130435)
Threat to humans:  harmless


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