Redescription of Nothobranchius lucius and description of a new species from Mafia Island, eastern Tanzania (Cyprinodontiformes, Aplocheilidae)

Wilson J.E.M Costa

doi:10.3897/zse.93.11041

Abstract

Examination of specimens listed in the original description of Nothobranchius lucius revealed that they belong to two species. Nothobranchius lucius is redescribed based on the type series and other specimens collected in the type locality area, the Kibasira Swamp area, Rufiji River basin, Tanzania, at elevations between 250 and 300 m. Nothobranchius insularis sp. n. is described on the basis of specimens collected in the north part of Mafia Island, Tanzania, at about 10–15 m elevation. Nothobranchius lucius and N. insularis are considered closely related species based on the shared presence of long jaws; caudal fin, in males, with a broad dark grey to black band on its posterior margin; black dots over the whole flank, in females; metapterygoid curved, with its middle and dorsal portions separated from the sympletic by a broad interspace; and posterior process of the quadrate shorter than the ventral length of the quadrate without process. Characters useful to distinguish them include premaxillary dentition, caudal fin shape, colour pattern of flank and unpaired fins in females, fin length, and number of neuromasts of the posterior section of the anterior supraorbital series. Both species are members of a group that also includes N. elongatus, N. hengstleri, N. interruptus, N. jubbi, N. krammeri, and N. melanospilus, which are all diagnosed by the presence of two neuromasts in the anterior section of the anterior supraorbital series.

Highlights

The East Africa region comprising the coastal forests of south-eastern Kenya and eastern Tanzania is an important centre of biological diversity often known as the East Africa biodiversity hotspot (EABH), with high occurrence of endemic species (Myers et al 2000, Azeria et al 2007)
Wildekamp et al (2009) designated the type series of N. lucius containing the holotype and 22 paratypes that were collected in the Kilombero River drainage
Such discrepancy supports the idea that the number of specimens used in the description was larger than that reported in the type material list, even when adding specimens listed under the non-types section that includes material described as N. insularis

Summary

Introduction

The East Africa region comprising the coastal forests of south-eastern Kenya and eastern Tanzania is an important centre of biological diversity often known as the East Africa biodiversity hotspot (EABH), with high occurrence of endemic species (Myers et al 2000, Azeria et al 2007) This region exhibits the greatest species diversity of Nothobranchius Peters, 1868, a killifish genus that occurs in a wide geographical portion of central and eastern Africa (e.g., Parenti 1981). Species of Nothobranchius and other African and South American aplocheiloid killifishes possessing this uncommon life cycle have been equivocally called annual fishes, reflecting the past belief that these fishes have a single generation per year (e.g., Myers 1942) Aplocheiloid killifishes with this life cycle have been alternatively known as seasonal killifishes in more recent studies (e.g., Costa 2002)

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Results

Conclusion