Wednesday, August 12, 2015

[Herpetology • 2011] Chatogekko amazonicus • A New Genus of Miniaturized and Pug-nosed Gecko (Sphaerodactylidae: Gekkota) from South America

Figure 4. Chatogekko amazonicus specimens.
A, lateral view of the head showing 2–4 loreal scales (ls); B, dorsal view of the left hand showing the inner supero-lateral and outer supero-lateral (isl and osl, Fig. 5B); C, ventral view of the left hand showing the inner infero-lateral and outer infero-lateral (iil and oil, Fig. 5C); and D, keeled scales along the dorsal surface of the body. A–C, USNM 288775; D, MZUSP 91394. Scale bar = 1 mm.
Figure 8. Articulated skeleton of Chatogekko sp. Specimen (USNM 289061) from Reserva Biologica Rio Trombetas, Pará, Brazil. Scale bar = 10 mm.

Sphaerodactyl geckos comprise five genera distributed across Central and South America and the Caribbean. We estimated phylogenetic relationships among sphaerodactyl genera using both separate and combined analyses of seven nuclear genes. Relationships among genera were incongruent at different loci and phylogenies were characterized by short, in some cases zero length, internal branches and poor phylogenetic support at most nodes. We recovered a polyphyletic Coleodactylus, with Coleodactylus amazonicus being deeply divergent from the remaining Coleodactylus species sampled. The C. amazonicus lineage possessed unique codon deletions in the genes PTPN12 and RBMX while the remaining Coleodactylus species had unique codon deletions in RAG1. Topology tests could not reject a monophyletic Coleodactylus, but we show that short internal branch lengths decreased the accuracy of topology tests because there were not enough data along short branches to support one phylogenetic hypothesis over another. Morphological data corroborated results of the molecular phylogeny, with Coleodactylus exhibiting substantial morphological heterogeneity. We identified a suite of unique craniofacial features that differentiate C. amazonicus not only from other Coleodactylus species, but also from all other geckos. We describe this novel sphaerodactyl lineage as a new genus, Chatogekko gen. nov. We present a detailed osteology of Chatogekko, characterizing osteological correlates of miniaturization that provide a framework for future studies in sphaerodactyl systematics and biology.

Keywords: Amazon, Chatogekko gen. nov., Coleodactylus, lizard, morphology, osteology, phylogeny, polytomy, Squamata


Type species: Sphaerodactylus amazonicus (Andersson, 1918)

Distribution: Central and eastern Amazonia, including the Brazilian states of Acre, Amazonas, Rondônia, Mato Grosso, Roraima, Pará, and Amapá; French Guiana; Guyana; Suriname; the Venezuelan state of Amazonas; and northern Bolivia (Gasc, 1990; Avila-Pires, 1995; Langstroth, 2005; Geurgas & Rodrigues, 2010).

Natural history: Chatogekko lives in the leaf litter in a variety of undisturbed lowland forested habitats (Vitt et al., 2005). These geckos are active throughout the day although they do not bask (Hoogmoed, 1973). Diet is made up of small insects including springtails, mites and ticks, termites, homopterans, and larval insects (Hoogmoed, 1973; Ramos, 1981; Vitt et al., 2005). Females lay one egg per clutch and can produce several clutches during the year (Hoogmoed, 1973; Gasc, 1990). Chatogekko can be locally very abundant but appears to be negatively affected by forest fragmentation (Carvalho et al., 2008).

Etymology: A composite word from the Spanish and Portuguese ‘Chato’, derived from the Greek ‘Platus’, meaning ‘flat’ and referring to its pug-nosed snout; and gekko from the Malay ‘gekoq’, onomatopoeic of the call of the species Gekko gecko and the common name to all limbed gekkotans. A Sri Lankan origin for the word gekko, derived from the Sinhalese word ‘gego’, is also possible (de Silva & Bauer, 2008). The name is masculine. 

Species composition: Chatogekko amazonicus (Andersson, 1918). In addition, the names C. zernyi (Wettstein, 1928) and C. guimaraesi (Vanzolini, 1957) are available for populations from eastern Amazonia and southwest Amazon, respectively. See Discussion for details.

Tony Gamble, Juan D Daza, Guarino R Colli, Laurie J Vitt and Aaron M Bauer. 2011. A New Genus of Miniaturized and Pug-nosed Gecko from South America (Sphaerodactylidae: Gekkota). Zool. J. Linn. Soc. 163(4): 1244–1266.  doi:  10.1111/j.1096-3642.2011.00741.x