THE NOTHOBRANCHIUS SITE

MRAC 2019.016.P.0036, holotype, male, 50.5 mm SL; Tanzania: upper Wembere drainage: Mhwala system: seasonal pool on the road between Tabora and Itigi, 05°18'14" S, 33°26'04" E; W. Krammer, 29 Apr 2018 [Bumburi TZHK 2018-03].

MRAC 2019.016.P.0037–0038 (2)

Nothobranchius hoermanni belongs to the N. ugandensis species group presenting the following combination of characters in males: body coloration light blue with red to red-brown scale margins; frontal part of head red-brown and throat light blue or red; caudal fin uniform red; and anal fin light blue or yellow with red-brown spotted pattern. Nothobranchius hoermanni differs from all other members of the N. ugandensis species group by a red throat; light blue anal fin with red-brown spots and stripes proximally and medially, and broad light blue distal zone without markings; pectoral fin hyaline with red-brown stripes parallel to fin rays; exposed branchiostegal membrane red-brown, with cream distal margin; suborbital depth 28 % HL (vs. 19–27) (Nagy et al., 2020).

Subgenus: Zononothobranchius

Species group: N. ugandensis group

Nothobranchius hoermanni was established as a species by Nagy, Watters & Bellstedt in Nagy et al. (2020).

Tanzania: upper Wembere drainage: Mhwala system: seasonal pool on the road between Tabora and Itigi, 05°18'14" S, 33°26'04" E.

Nothobranchius hoermanni is endemic to seasonal freshwater habitats in central Tanzania. It is currently known from ephemeral pools and marshes associated with the Mhwala system in the upper Wembere drainage, as well as the Wala system, a tributary of the Malagarasi drainage. The type locality is associated with the headwaters of the Mhwala system (Nagy et al., 2020).​

Southern Eastern Rift (566)

1168–1177 m

At the type locality, the water was turbid, the bottom of the pool not visible. The water hardness was approximately 3° German hardness and the pH was 6.0 (Krammer, pers. comm). Water parameters of another observation of this species at the Mhwala River TAN 03-10 location, measured by Watters, are as follows: temperature 23°C; pH 8.6; conductivity 40 µS; and turbid (Nagy et al. 2020).

At the collecting localities, N. hoermanni can be found syntopic with N. sonjae and N. neumanni.

This species has an annual life cycle.

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

Maximum size reported: 50.5 mm SL; MRAC 2019.016.P.0036, holotype, male (Nagy et al., 2020)

Diploid chromosome number 2n = 36, NF = 62, karyotype structure 8m+18sm+10st/a (Krysanov et al., 2023).

Karyotype structure unique in the genus.

The specific name is given in honour of Alwin Hörmann from Kühnhausen in Germany, a well-known aquarist and breeder of Nothobranchius fishes. He maintained and propagated the wild specimens collected in the field by Werner Krammer, during the field trip organized by Sonja and Holger Hengstler. Without his dedication and expertise, the population from the type locality would not have been available for researchers and others. A noun in genitive case.

Vulnerable B1ab(iii)+2ab(iii) (Nagy & Watters, 2021)

    Nagy, B., B. R. Watters, P. D. W. van der Merwe, F. P. D. Cotterill & D. U. Bellstedt. 2020. Review of the Nothobranchius ugandensis species group from the inland plateau of eastern Africa with descriptions of six new species (Teleostei: Nothobranchiidae). Ichthyological Exploration of Freshwaters, 30 (1): 21–73. [taxonomy as Nothobranchius hoermanni, distribution, ecology, phylogeny, systematics]

    Nagy, B. & B. R. Watters. 2021. Nothobranchius hoermanni. The IUCN Red List of Threatened Species: e.T175184881A175184889. [conservation]

    Krysanov, E. Y., B. Nagy, B. R. Watters, A. Sember & S. A. Simanovsky. 2023. Karyotype differentiation in the Nothobranchius ugandensis species group (Teleostei, Cyprinodontiformes), seasonal fishes from the east African inland plateau, in the context of phylogeny and biogeography. Comparative Cytogenetics, 17 (1): 13–29. [chromosomes]