Saturday, February 18, 2012

[Herpetology • 2006] 3 new Rhampholeon | R. beraduccii, R. acuminatus & R. viridus • The pygmy chameleons of the eastern Arc range (Tanzania): Evolutionary relationships

The pygmy chameleons of the Eastern Arc Range forests in Tanzania are reviewed on the basis of  known  and newly  collected material. Two new species be longing to Rhampholeon (Rhinodigitum) and one to Rh. (Rhampholeon) from the Pare, Nguru and Mahenge Mountains are described. The status and distribution of the other species known in the area are reviewed, and an identification key is provided. The phylogenetic relationships between these taxa are discussed on the basis of small and large mt-rDNA subunits sequences and the relative importance of some morphological characters is evaluated. Hypotheses about the evolution of the group in the area are presented.
Key words: biodiversity hotspot, biogeography, molecular systematics, Rhampholeon, Rieppeleon

Rhampholeon (Rhinodigitum) beraduccii n. sp.

Etymology. The new species is named in honour of Joe Beraducci, Arusha, Tanzania, as an appreciation for his generous assistance and help provided to us and to numerous other scientists working in the EAR.

Distribution and ecology. Rh. beraduccii is to date only known from the vicinity of Sali in the Mahenge mountains, an isolated massif separated from the Udzungwa range by the Kilombero valley. All animals were found alone, on low shrubs or herbs, within a few centimetres of the ground, in open land, in the immediate vicinity of the village.

Rhampholeon (Rhinodigitum) acuminatus n. sp.

Etymology. From Latin acuminare (to sharpen), in reference to the numerous sharp spines found on the head and body

Distribution and ecology. So far Rh. acuminatus is known from a single population in an Afro-montane rainforest between 1500 and 1600 m above the village of Ubili in the Nguru mountains. The species seems to be locally abundant. Six specimens have been collected for the present description; another six have been transferred to a reptile park in Arusha to attempt captive breeding. Most animals have been found between 50 cm and 2 m high on large ferns and shrubs, although several have been spotted up to an estimated 3-4 m high. This spatial distribution is rather unusual for pygmy chameleons, which generally stay closer to the ground. Interestingly it is comparable in its arboreal inclination to the morphologically similar Rh. spinosus from the Usambara mountains. The living specimens laid 2-4 eggs, hatching in January (J. Beraducci, Arusha, in litt.).

Rhampholeon (Rhampholeon) viridis n. sp. 

Etymology. The specific name derives from Latin viridis (green) and refers to the rich green colour of the males.

Distribution and ecology. This species inhabits the undergrowth and lower story vegetation of the submontane evergreen forests of the South and North Pare mountains. Its occurrence in the West Usambara is based on a single specimen in the British Museum collected in 1980 but its presence in these mountains has not since been reconfirmed. The holotype was collected at an altitude of 1450 m, but specimens have been found up to 2070 m in the South Pare and 1700 m in the North Pare. These forests are typical examples of the Afromontane forests that are dominated by emergent trees such as  Albizia gummifera, Macaranga kilimandscharica, Xymalos monospora, Ocotea usambarensis, Podocarpus latifolius and Chrysophyllum gorongosanum.
When handled these chameleons produced an easily felt “buzzing” vibration, particularly if touched lightly on the back. At the time of collection in early July, an adult male and female chameleon were found sleeping within a few centimetres of each other, indicating pairing off and thus possible recent past or potentially future mating activity.

Mariaux, Jean and Colin R. Tilbury. 2006. The pygmy chameleons of the eastern Arc range (Tanzania): Evolutionary relationships and the description of three new species of Rhampholeon (Sauria: Chamaeleonidae). Herpetological Journal. 16 (3): 315-331: [Fulltext]