Abstract
Madagascan skinks of the genus Mabuya can be divided into two groups based on the shape of the subocular scale, which is rectangular in the aureopunctata-Group and trapezoidal in the elegansGroup. The former group includes Mabuya aureopunctata, M. betsileana, M. boettgeri, and M. vato; the latter includes M. elegans, M. gravenhorsti, and M. madagascariensis. We describe herein a new species of the aureopunctata-Group, Mabuya dumasi, which differs from all other species of this group in having a distinctive longitudinal row of white spots on the side of the neck bordered above by a coextensive, dark brown or black, dorsolateral stripe. Mabuya dumasi differs further from M. boettgeri in lacking the body and neck stripes of the latter species; from M. aureopunctata and M. vato in lacking white spots on the dorsum of the head, neck, and anterior body, which are present in the latter two species; and from M. betsiliana in having fewer scales between the postmentals and the cloaca (fewer than 61 in M. dumasi, 71 in M. betsiliana). Mabuya dumasi was found at two sites 270 km apart in the dry regions of southern Madagascar: Amboanemba, 46 km N Amboasary, in dry spiny forest; and Zombitsy, 113 km NE Toliara, in dry deciduous forest. Although the new species is known from only nine specimens taken at two localities, there is no reason to believe it is threatened or endangered. It occurs in at least two distinctive habitats, and new localities are likely to be found when the region is adequately surveyed for reptiles. The ecological relationships among the Madagascan Mabuya are discussed, and an updated key to the eight species of Madagascan Mabuya is provided. The scincid subfamily Lygosominae is represented in Madagascar only by the genera Cryptoblepharus and Mabuya. A single, non-endemic species of Cryptoblepharus, C. boutoni, occurs in Madagascar, and this species apparently is a recent colonizer, either from Africa or the Australasian region. By contrast, Mabuya has had a longer history in Madagascar as is indicated by the modest radiation of seven species, all of which are endemic (Brygoo, 1983; Nussbaum and Raxworthy, 1994). The seven currently recognized species of Madagascan mabuyas can be divided into two groups on the basis of the shape of the subocular scale, which is normally the fifth supralabial scale. The aureopunctata-Group, characterized by a rectangular subocular scale, consists of four species: Mabuya aureopunctata, M. betsileana, M. boettgeri, and M. vato. Mabuya betsileana is a problematic form nearly identical to the west African M. perroteti. It is known only from the holotype, which may have been collected in Africa rather than Madagascar (Brygoo, 1983). The second group of three species, the elegans-Group, is distinguished by a trapezoidal subocular scale in which the lower border is much shorter than the upper border. This condition is caused by intrusion of the adjacent anterior supralabial scale into the space normally occupied by the anteroventral portion of the subocular scale. The elegans-Group consists of Mabuya elegans, M. gravenhorsti, and M. madagascariensis. Some Madagascan lizard communities studied by us have mabuyas of both the aureopunctataand elegans-Groups that are difficult to assign to species because of intermediacy of characters. We believe this is caused by hybridization, and we are collecting tissues for DNA and allozyme studies to resolve these problems. Hybridization seems especially evident between Mabuya elegans and M. gravenhorsti, both in northern and southern Madagascar, and between M. aureopunctata and M. gravenhorsti in southern Madagascar. We recently discovered two populations of a distinctive new species of the aureopunctataGroup that clearly are not of hybrid origin. These two populations occur in Zombitsy Forest and near Amboanemba river crossing, 270 km apart in the dry forests of southern Madagascar. In this paper, we describe this new species, briefly discuss its distributional and ecological relationships with other species of the genus, and provide an updated key to the Madagascan species of Mabuya. MATERIALS AND METHODS Specimens were photographed soon after capture to document color, which fades in preservative. Individuals were killed by injecting concentrated chlorobutanol, fixed in 10% buffered formalin, soaked in water to remove the formalin, and transferred to a final solution of 70% ethanol. This content downloaded from 207.46.13.57 on Thu, 08 Sep 2016 04:39:55 UTC All use subject to http://about.jstor.org/terms NEW SPECIES OF MABUYA
Published Version
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