Nothobranchius lourensi

description

Description. General body features illustrated by Figures 6 A – D. Morphometric and meristic characters of examined material are summarized in Table 6. Male: Medium-sized Nothobranchius species, maximum recorded size 40.6 mm SL. General body shape robust, laterally compressed and deep. Greatest body depth at pelvic-fin origin, 28.6 – 34.0 % 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 144 – 152 % of its depth. Anus situated directly in front of anal-fin origin. Head moderately long (29.2 – 32.8 % SL), laterally compressed, deeper than wide (head width 64 – 70 % 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 distributed conical teeth on inne

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 lourensi is distinguished from all the other members of the genus Nothobranchius by the unique combination of diagnostic characters of male colouration comprising: blue-green scales with dark brown posterior scale margins, creating a reticulation on the body, with a chevron pattern on the posterior part of trunk; light blue throat; anal and caudal fins with 8 – 12 distinct narrow to slender bands on the entire fin, perpendicular to fin rays, alternating red-brown and light blue to light yellow, with iridescent light blue to yellow subdistal band and dark grey to black distal band; dorsal-fin anterior half with irregular red brown spots and stripes parallel to fin rays, whereas posterior half with alternating red-brown and light blue to light yellow narrow to slender bands, perpendicular to fin rays; as well as having an anal fin with posterior lower margin straight to mildly concave. Also, the female has a grey-brown body, with a dark grey chevron pattern on the posterior half of trunk.

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 lourensi is endemic to seasonal freshwater habitats in coastal Tanzania and is the most widespread member of the Aphyobranchius subgenus, occurring most abundantly in the marginal and peripheral zones of the Kibasira Swamp in the Kilombero River valley but relatively sparsely elsewhere (Fig. 1). The Kilombero system represents a fairly remote component of the Rufiji River system, connected to it through the Ulanga River, the downstream continuation of the Kilombero River. Relatively rare, isolated, single site occurrences have also been reported from: the lower Ruvu River near Kwaraza, representing the type location; a couple of sites in the lower Rufiji River system, one associated with the Ruhoi River and another situated 2 km south of the main course of the Rufiji River near where it approaches the delta; a single occurrence is also known from the Luhule / Luhute River floodplain within the so-called Mbezi Triangle (sensu Watters et al. 2007; Watters 2009). Conservation status. Nothobranchius lourensi has been evaluated as Near Threatened (Nagy & Watters 2019 d). The known extent of occurrence (EOO) is 28,006 km ². Within its area of distribution, th

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 77 - 16 - P- 28, holotype, male, 40.6 mm SL; – RMCA 77 - 16 - P- 29 - 33, 5 males, 39.3 mm SL, 4 females, 30.4 – 35.4 mm SL; Tanzania: Kwaraza village; approx. 06 ° 41.9 ’ S, 38 ° 42.3 ’ E; R. Wildekamp, T. Steinfort, R. van Haarlem; 12 June 1976; field code: T 76 - 8. Additional material examined. 3 males, 32.5 – 35.6 mm SL; Tanzania: Kilombero drainage, Ifakara; 08 ° 10.042 ’ S, 36 ° 41.611 ’ E; B. Watters, R. Wildekamp, I. Sainthouse; 7 June 1995; field code: TAN 95 - 4.

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