Nothobranchius insularis

description

Colouration in alcohol (Fig. 3). Males. Flank, dorsum and head light brown, darker on posterior portion of scales of dorsal portion of flank, dorsum and opercle; venter pinkish grey; branchiostegal membrane dark grey. Dorsal and anal fins hyaline with transverse series of grey spots, almost inconspicuous in anal fin. Caudal fin pale yellow with dark grey to black stripe along whole fin margin, broader on posterior margin. Pectoral fin hyaline, pelvic fin greyish hyaline with black tip. Females. Flank and dorsum pale brown, side of head and venter pale yellow; vertically elongated dark grey to black dots irregularly arranged in oblique rows on whole flank; sometimes few pale grey dots on opercular region. Unpaired fins hyaline; elongated grey dots on basal portion of dorsal fin; anal and caudal fin often without dark marks, sometimes with almost inconspicuous pale grey dots on basal portion. Paired fins hyaline.

Redescription of Nothobranchiuslucius and description of a new species from Mafia Island, eastern Tanzania (Cyprinodontiformes, Aplocheilidae)

description

Description. Morphometric data appear in Table 2. Dorsal and ventral profiles slightly convex from snout to posterior end of dorsal and anal-fin bases, about straight on caudal peduncle. Body relatively slender, compressed. Greatest body depth at vertical just in front of pelvic-fin base. Jaws slightly elongated, snout pointed in lateral view. Jaw teeth canine, numerous, irregularly arranged, outer teeth greater than internal teeth. Gill-rakers of first branchial arch 4 - 5 + 14 - 15. Six branchiostegal rays. Dorsal and anal fins broad in males, extremity rounded, with short filamentous rays along distal margin, dorsal fin slightly longer than anal fin; in females, dorsal fin rounded, anal fin sub-triangular and slightly longer than dorsal fin. Caudal fin subtruncate. Pectoral fin rounded, posterior extremity between pelvic-fin base and anus. Pelvic fin small, tip reaching between anus and urogenital papilla; pelvic-fin bases medially in close proximity. Dorsal-fin origin on vertical between base of first and third anal-fin rays. Dorsal-fin rays 15 - 16; anal-fin rays 16 - 18; caudal-fin rays 29 - 30; pectoral-fin rays 19; pelvic-fin rays 6. Minute contact organs on first and secon

Redescription of Nothobranchiuslucius and description of a new species from Mafia Island, eastern Tanzania (Cyprinodontiformes, Aplocheilidae)

diagnosis

Diagnosis. Nothobranchius insularis is distinguished from all species of the Nothobranchius melanospilus group, except Nothobranchius lucius, in possessing snout pointed in lateral view, jaws moderately long (vs. snout blunt to weakly pointed, jaws short); caudal fin, in males, with broad dark grey to black band on the posterior margin (vs. narrow); presence, in females, of dark dots over the whole flank (dark dots when present restricted to the posterior portion of the flank). The new species differs from Nothobranchius lucius by having inner premaxillary teeth smaller than teeth of the outer premaxillary tooth row (vs. larger); caudal fin subtruncate in males (vs. rounded); in females, flank dark dots are vertically elongated and often arranged in oblique rows (vs. dots rounded, arranged in horizontal rows); unpaired fins, in females, with dark grey dots when present restricted to their basal portion (extending over most fin); caudal, pectoral and pelvic fins shorter (caudal fin length 26.9 - 29.6 % SL in males and 22.8 - 27.4 % SL in females of Nothobranchius insularis, vs. 31.3 - 34.9 % SL in males and 30.3 - 32.9 % SL in females of Nothobranchius lucius; pectoral-fin length 17

Redescription of Nothobranchiuslucius and description of a new species from Mafia Island, eastern Tanzania (Cyprinodontiformes, Aplocheilidae)

distribution

Distribution. Nothobranchius insularis is known from two close localities in the northern part of the Mafia Island, Tanzania, at about 10 - 15 m asl (Fig. 2).

Redescription of Nothobranchiuslucius and description of a new species from Mafia Island, eastern Tanzania (Cyprinodontiformes, Aplocheilidae)