THE NOTHOBRANCHIUS SITE

MRAC 2018.015.P.0022, holotype, male, 40.0 mm SL; Tanzania: flooded grassy area with reeds adjacent to rice fields on SE side of road B 163, 40 km SW of Sengerema in the direction of Geita, or 17 km SW of Sima, or 67 km SW of Karumo ferry terminal, approx. 02°48' S, 32°29' E; B. Watters, I.  Sainthouse & M. Agnew, 15 May 1993, [field code: Ibanda TAN 93-12].

MRAC 2018.015.P.0023, MRAC B2.039.P.0010, MRAC 2018.015.P.0024-8 (5), MRAC 2018.015.P.0029, MRAC 2018.015.P.0030-0035 (6)

Nothobranchius skeltoni is distinguished from all other species of the genus by the following characters in males: body coloration light blue with grey to brown scale margins; anal fin grey to red-grey with irregular dark grey spots proximally, followed by a broad dark red to maroon medial band, a narrow light grey subdistal band, 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 dark red to maroon medial band and narrow black distal margin. Furthermore, it differs from the other members of the N. taeniopygus species group in central and western Tanzania by a body depth at pelvic-fin origin 26.3-30.0 % SL (vs. 30.3-37.6); suborbital depth 15-22 % HL (vs. 23-31); caudal peduncle depth 11.8-12.9 % SL (12.9-16.8); and caudal peduncle length 160-169 in % its depth (vs. 119-151) (Watters et al., 2019).

​Subgenus: Zononothobranchius

Species group: N. taeniopygus group

Following its discovery in 1990, populations of this species were referred to N. taeniopygus, based on some 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. 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 3’ (Wildekamp, 2004). Morphometric and molecular analyses confirmed the distinction from N. taeniopygus and the species was described as Nothobranchius skeltoni by Watters, Nagy & Bellstedt in Watters et al. in 2019.

Tanzania: flooded grassy area with reeds adjacent to rice fields on SE side of road B 163, 40 km SW of Sengerema in the direction of Geita, or 17 km SW of Sima, or 67 km SW of Karumo ferry terminal, approx. 02°48' S, 32°29' E.

This species is endemic to north-central Tanzania. The known occurrence of Nothobranchius skeltoni is limited to six sites: four within 17-26 km east of Mwanza, Tanzania, and two sites very close to each other, including its type locality, approximately 56 km southwest of Mwanza, near the village of Ibanda. All sites are close to Lake Victoria. Two of the eastern sites are also very close to each other and essentially within the same local drainage system. The latter sites are associated with minor seasonal drainage flowing into Lake Victoria, whereas the two westernmost localities are associated with a seasonal stream and marsh system, the Nyaruha River and tributaries, draining into the Smith Sound arm of the Mwanza Gulf. The fact that the general area within which the sites occur has been fairly well investigated suggests that this species is relatively uncommon.

Lake Victoria basin (521)

1171–1190 m

Water parameters (Watters & Nagy, personal data): temperature of 21–29°C; pH of 7.3–8.3; conductivity of 70–200 µS; and turbid (Nagy & Watters, 2020)

None

This species has a semi-annual life cycle.

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

Maximum size reported: 53 mm SL; MRAC 2018.015.P.0023, paratype, male (Watters et al., 2019)

Not known

The specific name is given in honour of Professor Paul Skelton, emeritus managing director of the South African Institute of Aquatic Biodiversity, for his dedication to the science of ichthyology, and in recognition of his vast contributions to the study and documentation of African freshwater fishes and biodiversity. A noun in genitive.

​​Vulnerable B1ab(iii)+2ab(iii) (Nagy & Watters, 2020)

    Østergaard, K. 1991. Nothobranchius in Sukumaland. Journal of the American Killifish Association, 24: 202–212. [discovery and collecting as Nothobranchius sp. Bujora] 

    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 skeltoni, distribution, ecology, phylogeny, systematics]

    Nagy, B. & B. R. Watters. 2020. Nothobranchius skeltoni. The IUCN Red List of Threatened Species: e.T156302361A156302373. [conservation]

    Nagy, B. 2020. An expedition around Lake Victoria. Tropical Fish Hobbyist, #744, Sep/Oct 2020, 69 (1): 44–50. [collecting]