[latin] Batis crypta | [UK] Dark Batis | [year] 2006 | [status] LEAST CONCERN

Dark Batis new species



The forest batis, Batis mixta, is a common bird of the forests of the Eastern Arc Mountains of Tanzania and in some adjacent montane and coastal forests. Through new collecting efforts in most of this range we documented a well-marked change in morphology in the middle of the range. Supplementary genetic studies of the historical population structure suggest connectivity among the south-western and northern/coastal populations, but not between these parapatric groups. It is concluded that two species are involved, and a new name B. crypta is proposed for the south-western populations. A marked genetic break also exists towards B. capensis sola in northern Malawi. The morphologically distinctive form reichenowi in south-eastern Tanzania is genetically nested within B. mixta, and for now we keep it as a subspecies of B. mixta. The many species of Batis (Platysteiridae, Dickinson 2003; Fuchs et al. 2004) are confusing because of the complex variation in sexual dimorphism, combinations of plumage characters and eye colour changes between different geographical populations. This also applies to the subgroup of forest-dwelling forms of eastern Africa. Opinions about how to classify these forms have varied, but they are usually (Dowsett and Dowsett-Lemaire 1993; Harris and Franklin 2000) divided into the species Batis capensis (Cape batis of southeastern Africa, including the form reichenowi, see Dowsett-Lemaire 1989, contra Lawson 1986; Traylor 1986), B. fratrum (Woodward?s batis of Mozambique coastal forests), B. margaritae (Margaret?s batis of Zambia and Angola), B. diops (Ruwenzori batis of the Albertine Rift Mts) and B. mixta (forest batis, mainly in Tanzanian montane forests). The affinities of B. mixta, and its rank as an independent species, have been discussed by Dowsett and Dowsett-Lemaire (1980), Lawson (1986) and Dowsett- Lemaire (1989). Lawson (1986) placed the B. mixta populations of the Kenyan coastal forests in a separate subspecies ultima, diagnosed by white supralores in the male, but although he examined material from the entire range he did not recognise any differences between other populations. It was therefore a surprise when, as a result of a comprehensive new collecting effort for analysing speciation patterns of afromontane forest birds (Bowie 2003; Bowie et al. 2004a, 2006; J.Fjeldsa° , unpublished), we discovered a clear-cut morphological change in B. mixta in central Tanzania. This was unexpected, since this ??species?? appears to be fairly continuously distributed along all the Eastern Arc Mountains of Tanzania and some adjacent highlands. It is generally common, even in degraded forest, and it sometimes ventures out into the widespread Brachystegia (??miombo??) woodlands and (seasonally) into wooded foothill habitats. It is also known to breed in some semi-evergreen coastal forests. Because of this flexibility in habitat use and apparent seasonal movements (Burgess and Mlingwa 2000; Romdal 2001), we would expect some gene flow between populations. A detailed morphological study, supplemented by genetic data to assess the historical population structure, suggests some connectivity among populations in the south-western and northern parts of the range, but not between these two population groups.

Jon Fjeldså, Bowie, R.C.K. & Kiure, J. 2006. The forest batis, Batis mixta, is two species: description of a new, narrowly distributed Batis species in the Eastern Arc biodiversity hotspot. ? Journal of Ornithology 147: 578?590

Download PDF