Nothobranchius fuscotaeniatus

description

Description. General body features illustrated by Figures 7 A – B. Morphometric and meristic characters of examined material are summarized in Table 7. Male: Medium-sized Nothobranchius species, maximum recorded size 43.4 mm SL. General body shape robust, laterally compressed and deep. Greatest body depth at vertical passing through pelvic-fin origin, 32.5 – 35.3 % SL. Greatest body width at pectoral-fin base with body progressively narrowing towards caudal-fin base. Dorsal profile convex from tip of snout to dorsal-fin origin, 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 146 – 153 % of its depth. Anus situated directly in front of anal-fin origin. Head moderately long (30.4 – 33.6 % SL), laterally compressed, deeper than wide (head width 64 – 69 % of its depth). Snout distinctly 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 distribu

A review and redefinition of the subgenus Aphyobranchius Wildekamp, 1977, in the seasonal killifish genus Nothobranchius Peters, 1868 (Teleostei: Nothobranchiidae), from ephemeral wetlands of eastern Tanzania

diagnosis

Diagnosis. Nothobranchius fuscotaeniatus is here assigned to the N. lourensi species group of the subgenus Aphyobranchius by presenting the following combination of characters in males, compared to those of other subgenera: anal fin trapezoidal in shape with a concave lower margin (vs. rounded with convex lower margin); caudal fin rounded with 2 – 3 central rays slightly elongated forming a mild central lobe (vs. central lobe absent); spawning behaviour in mid-water levels (vs. spawning directly into the substrate), and molecular phylogenetic relationships. Nothobranchius fuscotaeniatus is further distinguished from all the other members of the genus Nothobranchius by the unique diagnostic characters of male colouration comprising a green-blue body with 10 – 12 distinct red-brown crossbars on entire trunk that extend into dorsal and anal fins; anal and dorsal fins green-blue with crossbars extending from trunk into the proximal and medial parts and with broad black distal band; caudal fin with slender yellow to yellow-green medial band and broad black distal band; as well as female colouration with a unique pattern of light blue and red-brown crossbars on the body and a light blue

A review and redefinition of the subgenus Aphyobranchius Wildekamp, 1977, in the seasonal killifish genus Nothobranchius Peters, 1868 (Teleostei: Nothobranchiidae), from ephemeral wetlands of eastern Tanzania

distribution

Distribution. Nothobranchius fuscotaeniatus is known from a single site only, comprising an originally thickly vegetated ditch on the immediate west side of a now defunct road, about 2 km southwards from the south bank terminus for the old ferry across the Rufiji River (Fig. 1). It is, therefore, within the lower Rufiji River drainage. Since the original discovery of this species by the first author and colleagues in May, 1997, and also soon after by Seegers (1997), numerous visits to that site have been unable to find it there again. Conservation status. Nothobranchius fuscotaeniatus is listed as Critically Endangered B 2 ab (iii) (Nagy & Watters 2019 e). The species is currently known only from the type locality with an area of occupancy (AOO) of 4 km 2. Several surveys in the years following the original discovery were unable to detect its presence at either the type locality or elsewhere in the drainage of the Rufiji River, whereas other congeners were found in abundance at the type locality and in the general area. As shown in Nagy & Watters (2021) and Figure 7 D herein, the type locality has been significantly modified since the species was first discovered in 1997. Extensive

A review and redefinition of the subgenus Aphyobranchius Wildekamp, 1977, in the seasonal killifish genus Nothobranchius Peters, 1868 (Teleostei: Nothobranchiidae), from ephemeral wetlands of eastern Tanzania

materials_examined

Material examined. RMCA 1997.082. P. 0032 - 0033, 1 male, 36.2 mm SL, 1 female, 24.2 mm SL; Tanzania: Rufiji drainage, Kitonga; 08 ° 03.13 ’ S, 39 ° 00.53 ’ E; B. Watters, R. Wildekamp, B. Cooper; 31 May 1997; field code: TAN 97 - 9. Additional material examined. 2 males, 35.1 – 43.4 mm SL, 1 female 25.9 mm SL; Tanzania: Rufiji drainage, Kitonga; 08 ° 03.13 ’ S, 39 ° 00.53 ’ E; B. Watters, R. Wildekamp, B. Cooper; 31 May 1997; field code: TAN 97 - 9.

A review and redefinition of the subgenus Aphyobranchius Wildekamp, 1977, in the seasonal killifish genus Nothobranchius Peters, 1868 (Teleostei: Nothobranchiidae), from ephemeral wetlands of eastern Tanzania