65.1 Friday, Jan. 6 A New Species of Hemidactylus Gecko Endemic to the Gulf of Guinea: A Story of Transoceanic Colonization Events MILLER, EC*; DREWES, RC; University of California, San Diego; California Academy of Sciences email@example.com
The Gulf of Guinea islands São Tomé and Príncipe are home to a poorly-known endemic herpetofauna. Native and non-native Hemidactylus geckos inhabit the islands, including the endemic Hemidactylus greefi (Greef’s giant gecko). Previous work has found species-level differences in mtDNA between populations found on São Tomé and Príncipe, requiring a closer analysis of morphological and molecular data in order to determine the level of divergence between the two island populations. Fourteen measurements were taken on 12 Príncipe specimens and 14 São Tomé specimens and standardized by snout-vent length, in addition to meristic counts. It was discovered that on São Tomé, individuals were significantly larger across all body measurements, and also had proportionally longer limbs and a more robust head. The two island populations can be visually distinguished by the divided lamellae counts on the third finger, tubercle scale size, and the number of preanal/femoral pores in males. We also sequenced 10 Príncipe and 12 São Tomé specimens for the nuclear intron &alpha-Enolase, which has an intermediate rate of change between those of mtDNA and other nuclear genes previously employed on this species. The two populations are distinguished by a fixed site difference. São Tomé geckos are much more genetically diverse than Príncipe geckos, having eight haplotypes for the gene compared to only two in Príncipe specimens. Not only does our data provide enough evidence to distinguish the two populations as different species, but the lack of genetic diversity in Príncipe geckos suggests a possible founder effect in which the Príncipe population is a result of a single colonization event originating from São Tomé. These results confirm that a description of the new species is needed, as well as the designation of a neotype to represent H. greefi.