THE NOTHOBRANCHIUS SITE

ZMB (not disclosed), holotype, female, 33 mm TL; Mombo, Deutsch-Ostafrika (presently in north-eastern Tanzania); J. Vosseler [unique, lost]

Nothobranchius vosseleri is a member of a group of Nothobranchius species, here referred to as N. melanospilus group, of relatively large size (up to 60 mm SL for N. melanospilus) and with a slender body (less than 30 % of SL) compared to the other species of the genus, and a distinct red caudal fin in male. Nothobranchius vosseleri can be distinguished from the other species of this group by a pointed snout, and the presence of a dark vertical bar through the iris (vs.none in the other members of the N. melanospilus group, except N. elongatus) (Wildekamp et al., 1998).

Subgenus: Adiniops

Species group: N. melanospilus group

Nothobranchius vosseleri was established as a species by Ahl in 1924. The original description was based on a single female specimen from Mombo in north-western Tanzania. Additionally, the unique holotype is no longer present in the collection of ZMB (Paepke & Seegers, 1986). Wildekamp (1977) regarded N. vosseleri as a possible synonym of N. palmqvisti, a species leaving nearby. However, field studies near Mombo led to understand the true identity of N. vosseleri and the species was redescribed by Wildekamp et al. in 1998, based on the more recent material.

Mombo, Deutsch-Ostafrika (presently in north-eastern Tanzania).

This species is endemic to seasonal freshwater habitats in north-eastern Tanzania. It is known from ephemeral pools and swamps in the upper and middle Pangani River floodplain, above the Pangani Falls, in north-eastern Tanzania.

Pangani (568)

286–699 m

Water parameters (Wildekamp et al., 1998; Watters personal data) are as follows: temperature of 23–31°C; pH of 7.0–8.3; conductivity of 180–>4040 µS; and typically turbid.

None

This species has a semi-annual life cycle.

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

Maximum size reported: 44.6 mm SL (MRAC 96-45-P-13-15, male)

Diploid chromosome number 2n = 38, NF = 60, karyotype structure 6m+16sm+16st/a (Krysanov & Demidova, 2018).

Karyotype structure unique in the genus.

The specific name is given in honour of Julius Vosseler, the discoverer of the species, who at that time worked as zoologist at the Amani Biological and Agricultural Institution in German East Africa.

Vulnerable B1ab(iii) (Nagy & Watters, 2019)

    Ahl, E. 1924. Neue afrikanische Zahnkarpfen aus dem zoologischen Museum Berlin. Zoologischer Anzeiger, 61 (3–4): 135–145. [taxonomy as Nothobranchius vosseleri]

    Wildekamp, R. H., B. R. Watters & I. F. N. Sainthouse. 1998. Redescription of Nothobranchius vosseleri (Cyprinodontiformes: Aplocheilidae) an annual fish from the Tanzanian coastal plains. Ichthyological Exploration of Freshwaters, 8 (4): 289–298. [systematics]

    Nagy, B. & B. R. Watters. 2019. Nothobranchius vosseleri. The IUCN Red List of Threatened Species: e.T55326766A58340574. [conservation]