Wednesday, July 27, 2016

[Herpetology • 2014] Adolfus masavaensis • Resolving Sky Island Speciation in Populations of East African Adolfus alleni (Sauria, Lacertidae)

Adolfus masavaensis 

Wagner, Greenbaum & Branch
in Wagner, Greenbaum, Malonza & Branch, 2014 

The genus Adolfus Sternfeld, 1912 currently contains three species from Equatorial Africa. Two of these occur in widespread, low- to mid-elevation habitats, but Adolfus alleni is only known from four montane peaks (Aberdares, Mt. Kenya, Cherangani Hills, Mt. Elgon) in Kenya and Uganda. An integrative approach using 58 morphological characters and genetic analyses of mitochondrial (16S and cyt b) and nuclear (c-mos and RAG1) DNA sequence data revealed differences between these populations, and indicated that A. alleni is a complex of at least two cryptic species. Herein, we describe the populations from the Aberdares and Mount Elgon as a new species, and restrict A. alleni to Mount Kenya. This action underscores the importance of conservation strategies to protect these montane peaks, which may harbour additional, unique evolutionary lineages. 

Key words. Uganda, Kenya, montane grassland, Squamata, Adolfus, systematics.

Adolfus masavaensis
Wagner, Greenbaum & Branch in Wagner, Greenbaum, Malonza & Branch, 2014

Diagnosis: This species is unique by the following combination of characters: small size (SVL 38.9–55.5 mm), low number of temporal scales (3–12; Mt. Elgon: 8–12, Aberdares: 3–5), low number of scales around midbody (19–23), and a vertebral stripe often including the occipital scale. 

Etymology: The English name of ‘Mount Elgon’ refers to the indigenous tribe of the Elgonyi who live on the southern slopes of the mountain. ‘Masava’ is the local name for Mount Elgon used by the tribes on the Ugandan side of the mountain, and is used to form the species name for the taxon described herein.

Distribution and habitat: Adolfus masavaensis sp. n. is known from the Mt. Elgon area and the Aberdare Range. Within the Mt. Elgon area, there is a single record from the Cherangani Hills (BMNH 1969.2584, Sondang, 3,150 m; Arnold 1989a) that probably represents a third distinct population of the new species, but still requires additional study. Like A. alleni, specimens of the new species were only found at high altitudes from 2,895.5 m (CAS 162680–81) to 3,372 m (ZFMK 75011), and are presumed to have similar habitat preferences, i.e., the Páramo-like [alpine] zone, a form of open grassland with Dendrosenecio battiscombei (Asteraceae). However, Angel (1925) mentioned a specimen from the bamboo forests on the Aberdares, at the lower altitudinal limit of the species, a zone that is ecologically distinct from the other species’ known habitats.

Conservation: Because of our division of A. alleni into two taxa, the conservation status of both species need to be reassessed. Adolfus alleni was categorised by the IUCN (Spawls 2010) as ‘Vulnerable’ due to its small area of occupancy of about 5,226 km2 , and because individuals were known from only four localities, even though they mainly occurred within National Parks (Mt. Kenya, Mt. Elgon, Aberdares).

However, because of our taxonomic partition, both species have more reduced areas of occupancy and are only known from one population (A. alleni, Mt. Kenya) and two clearly isolated populations (A. masavaensis sp. n., Aberdares/Mt. Elgon + Cherangani Hills), respectively, which may render their conservation status more critical. Habitat degradation was considered the major threat (Spawls 2010), because despite the protected status of the parks, moorlands were still being burned and the human population in proximity to the parks was dense. These observations now also apply to the new species Adolfus masavaensis sp. n.  

Philipp Wagner, Eli Greenbaum, Patrick Malonza and Bill Branch. 2014. Resolving Sky Island Speciation in Populations of East African Adolfus alleni (Sauria, Lacertidae). Salamandra. 50(1); 1-17.