Nothobranchius nikiforovi

biology_ecology

Ecology. The lower reaches of the Matandu drainage in south-eastern Tanzania, where N. nikiforovi occurs, has a unimodal rainfall pattern extending from November to April, inferring an annual mode of reproduction in this species. The mean annual rainfall decreases southwards along the coast and is around 1000 mm at the Matandu River (Hughes & Hughes 1992). Wetlands are at their lowest levels in August to September, when seasonal streams and most temporary habitats are dry. The type locality is a small temporary pool formed in the drainage of the seasonal Zinga River, a tributary of the Matandu River (Fig. 5). The habitat belongs to category 2.1.1 as defined by Watters (2014), representing ditches and excavated or eroded depressions associated with culverts along roads traversing the floodplain. At the end of the rainy season, the habitat was a shallow pool, about 10 m long and less than 5 m wide, and less than 1 m at the deepest point. At the type locality, all sampling took place in the same general habitat. The water was turbid, the bottom of the pool was not visible. Accompanying congeners consisted of N. cf. melanospilus. No water quality determinations were made at the time of

Nothobranchius nikiforovi, a new species of seasonal killifish from the lower Matandu drainage in south-eastern coastal Tanzania (Cyprinodontiformes Nothobranchiidae)

description

Description. General body features of males illustrated by Figure 4 A – C. Morphometric and meristic characters of holotype and paratypes summarised in Table 2. Relatively small-sized Nothobranchius species, maximum observed length of specimens examined 24.5 mm SL, although specimens were observed to attain 30 mm SL. General body shape robust, laterally compressed and deep. Greatest body depth at vertical passing through pelvic-fin origin: 25.3 – 31.6 % SL. Greatest body width at pectoral-fin base with body progressively narrowing towards caudal-fin base. Dorsal profile convex from tip of snout to base of last dorsal-fin ray; postdorsal profile slightly concave on caudal peduncle. Ventral profile convex from lower jaw to base of last anal-fin ray; postanal profile slightly concave on caudal peduncle from insertion of posteriormost anal-fin ray to caudal-fin base. Caudal peduncle deep, length 124 – 132 in % of its depth. Anus slightly anterior to anal-fin origin. Head moderately long (27.5 – 32.7 % SL), laterally compressed, deeper than wide (head width 64 – 71 in % of its depth). Snout slightly pointed, smaller than eye diameter. Mouth supraterminal, slightly oblique in profile. Ja

Nothobranchius nikiforovi, a new species of seasonal killifish from the lower Matandu drainage in south-eastern coastal Tanzania (Cyprinodontiformes Nothobranchiidae)

description

Figure 4 urn: lsid: zoobank. org: act: B 1465766 - 5959 - 4 EE 4 - 9 E 1 E-AF 82 EC 939 B 17

Nothobranchius nikiforovi, a new species of seasonal killifish from the lower Matandu drainage in south-eastern coastal Tanzania (Cyprinodontiformes Nothobranchiidae)

diagnosis

Diagnosis. Nothobranchius nikiforovi is distinguished from all other congeners, except N. eggersi, by males presenting two phenotypes; the blue phenotype having a bright iridescent light blue to blue-green body, with narrow red-brown scale margins creating irregular reticulated pattern forming chevron-shaped crossbars on posteroventral portion of body and median fins light blue with red-brown dotted pattern; the red phenotype has a dark red head, light blue dorsal and anal fins proximally and medially, dark red distally, with dark red stripes parallel to the fin rays, and plain dark red caudal fin. Nothobranchius nikiforovi differs from N. eggersi by male colour pattern: the blue phenotypes having median fins with dark grey distal portion, some of the rays of dorsal and anal fins with white tips only (vs. median fins light blue with distinct slender white distal band), the caudal fin lacking a spotted pattern (vs. dots arranged into irregular curved stripes); the red phenotype has a golden stripe between the nape and dorsal-fin origin (vs. light blue stripe), the dorsal and anal fin distal portion plain red and without light distal band (vs. with distinct narrow white distal band),

Nothobranchius nikiforovi, a new species of seasonal killifish from the lower Matandu drainage in south-eastern coastal Tanzania (Cyprinodontiformes Nothobranchiidae)