THE NOTHOBRANCHIUS SITE

MRAC 2018.015.P.0036, male, 41.9 mm SL; Tanzania: Rungwa drainage: small pool with grassy fringes, and associated narrow channel, in the course of the seasonal Rungwa River, 3 km south of Rungwa village, 06°57.5' S 33°31.0' E; B. Watters, B. Cooper & W. Bishopp, 19 May 2003; preserved in the field, [field code: Rungwa River TAN 03-6].

MRAC 2018.015.P.0037

Nothobranchius rungwaensis is distinguished from all other species of the genus by the following characters in males: body coloration light blue to blue-green with red-brown scale margins; anal fin yellow with a narrow red-brown submedial band, a broad yellow medial band with red to red-brown spots, and a broad black distal band; caudal fin light grey with slender semi-translucent dark grey distal band; pelvic fins light blue-grey, with broad yellow medial band with red-brown spots, and narrow black distal band. Furthermore, it differs from the other members of the N. taeniopygus species group in central and western Tanzania by a head width 54 % HL (vs. 56-73) and 62 % of its depth (63-77); interorbital width 38 % HL (vs. 39-52); postorbital length 46 % HL (vs. 47-63); snout length 22 % HL (vs. 16-22); and caudal peduncle length 119 % of its depth (vs. 121-169). (Watters et al., 2019)

​Subgenus: Zononothobranchius

Species group: N. taeniopygus group

Following its discovery in 1994, populations of this species were referred to as N. taeniopygus, based on general similarities of colour pattern with that species. Since the redescription by Wildekamp (1990), many more populations of members of the N. taeniopygus group across a wide distribution range in western and central Tanzania have been found. These resulted in the name N. taeniopygus or N. aff. taeniopygus being attached to various populations, and notable differences, primarily in colour pattern, led to the informal designation of numerous ‘phenotypes’ by Wildekamp (2004).

Populations of this species had been regarded as representing ‘phenotype 2’ (Wildekamp, 2004). Morphometric and molecular analyses confirmed the distinction from N. taeniopygus and the species was described as N. rungwaensis by Watters et al. in 2019.

Tanzania: Rungwa drainage: small pool with grassy fringes, and associated narrow channel, in the course of the seasonal Rungwa River, 3 km south of Rungwa village, 06°57.5' S 33°31.0' E.

This species is endemic to south-westernTanzania. It is known from two sites, including the type locality, which are within 12 km of each other, comprising seasonal pools associated with the upper Rungwa River and with the Musa tributary of the same system. The Rungwa River system occurs in south-western Tanzania and drains into Lake Rukwa. Additional sites inhabited by this species are likely to occur in the Rungwa system, especially in association with marshes in the lower-middle reaches.

Lake Rukwa (565)

1199–1230 m

Water parameters at the type locality (Watters, personal data): temperature of 26°C; pH of 8.2; conductivity of 100 µS; and turbid (Nagy & Watters, 2019).

None

This species has an annual life cycle.

Embryonic development under captive conditions in peat moss is about three to six months at room temperature.

Maximum size reported: 41.9 mm SL; MRAC 2018.015.P.0036, holotype, male, (Watters et al., 2019)

Not known

The specific name is in reference to the Rungwa River, in which drainage system this species is found. An adjective derived from the geographical name.

Vulnerable B1ab(iii)+2ab(iii) (Nagy & Watters, 2019)

    Watters, B. R., B. Nagy, P. D. W. van der Merwe, F. P. D. Cotterill & D. U. Bellstedt. 2019. Review of the Nothobranchius taeniopygus species group from central and western Tanzania with descriptions of five new species and redescription of Nothobranchius taeniopygus (Teleostei: Nothobranchiidae). Ichthyological Exploration of Freshwaters, IEF-1110, pp. 1–41. [taxonomy as Nothobranchius rungwaensis, distribution, ecology, phylogeny, systematics]

    Nagy, B. & B. R. Watters. 2020. Nothobranchius rungwaensis. The IUCN Red List of Threatened Species 2020: e.T156302297A156302311. [conservation]