endemic

The Curaçao Whiptail (Cnemidophorus murinus) (Squamata: Teiidae) was once considered to have two subspecies, C. m. murinus (endemic to Curaçao and Klein-Curaçao) and C. m. ruthveni (endemic to Bonaire and Klein-Bonaire), but the two are now considered separate species (Ugueto and Harvey 2010). Little has been published on the natural history of C. murinus. Most of the literature on the natural history of “C. murinus” actually pertains to C. ruthveni and includes studies on diet (Dearing and Schall 1992, Schall 1996), body temperature (Schall and Dearing 1994), metabolic expenditure (Bennett and Gleeson 1979), population density and energetics (Bennett and Gorman 1979), signaling behavior (Cooper et al. 2004), escape behavior (Cooper et al. 2003), and learning (Schall 2000). In contrast, published literature on C. murinus that deals with topics other than its taxonomy, morphology, and distribution is limited to a few notes on its parasites (Specian and Whittaker 1980), pathology (Hughes and Delis 2014), clutch size (van Buurt 2011), conservation (van Buurt 2006), and interactions with tourists (van Buurt 2011). Herein I add to the published knowledge of C. murinus with observations on diet and foraging.

A common response among lizards to the approach of a predator is to attempt to avoid detection by moving out of the predator’s view. This may involve moving to the opposite side of a twig or tree trunk, moving into a burrow, or moving into vegetation or other structures (McElroy 2019). Here, I report an unusual behavior to avoid detection in the Aruba Whiptail (Cnemidophorus arubensis), a teiid endemic to the island of Aruba. This behavior involves movement into a shadow in the open, with no further concealment.A common response among lizards to the approach of a predator is to attempt to avoid detection by moving out of the predator’s view. This may involve moving to the opposite side of a twig or tree trunk, moving into a burrow, or moving into vegetation or other structures (McElroy 2019). Here, I report an unusual behavior to avoid detection in the Aruba Whiptail (Cnemidophorus arubensis), a teiid endemic to the island of Aruba. This behavior involves movement into a shadow in the open, with no further concealment.

Three teiid species (Squamata: Teiidae) are endemic to the ABC islands (Aruba, Bonaire, and Curaçao) of the former Netherlands Antilles: the Aruba Whiptail (Cnemidophorus arubensis) of Aruba, the Bonaire Whiptail (C. ruthveni) of Bonaire and Klein-Bonaire, and the Curaçao Whiptail (C. murinus) of Curaçao and Klein-Curaçao. Before now, social displays have been described only for one of these three species: C. ruthveni (Baird et al. 2003). All three species engage in an arm-waving display that involves forelimb circumduction (Baird et al. 2003; van Buurt 2005; van Buurt 2011), which conveys social signals to conspecifics in some iguanian and lacertid lizard species (Carpenter et al. 1970; Verbeek 1972; Mitchell 1973). However, this behavior in the ABC island species of Cnemidophorus has not been shown to have a social function (Baird et al. 2003). Instead, experimental evidence demonstrates that in C. ruthveni it functions as a pursuit deterrent display that is performed in response to approaching humans, whom the lizard may view as potential predators (Cooper et al. 2004), although there are not yet any published reports of C. ruthveni performing the display in response to the approach of a non-human predator. My observations and those of others (van Buurt 2011) also confirm that in C. arubensis the display is performed in response to approaching humans.

Accurate assessment of species ranges is important not only for conservation planning but also for our understanding of their ecology and evolution (e.g., Kodric-Brown and Brown, 1993; Carlton, 1996; Blackburn and Gaston, 1998; Rondinini et al., 2006). Although several Lesser Antillean reptile groups show high levels of endemism, with most islands hosting at least one local endemic species (Lazell, 1972; Hedges et al., 2009; Tucker et al., 2017), it is not uncommon for Sphaerodactylus geckos to range across multiple islands (Schwartz and Henderson, 1991; Thorpe et al., 2008; Surget-Groba and Thorpe, 2012; Yuan et al., 2020). The Island Least Gecko, Sphaerodactylus sputator (Sparrman, 1784), is known to occur on the islands of Anguilla, St. Barthélemy, St. Eustatius, St. Kitts, St. Martin, and Nevis, as well as their satellite islands (King, 1962; Schwartz and Henderson, 1991; Malhotra and Thorpe, 1999; Powell et al., 2005; Questel, 2012, 2018). Here, we confirm the presence of S. sputator on Saba, from where, to the best of our knowledge, the species has not previously been reported (Schwartz and Thomas 1975; Schwartz and Henderson, 1991; Powell and Henderson 1996; Powell et al., 2005; Powell and Bauer 2012; Powell and Henderson 2012).

Abstract

The Lesser Antilles, in the Eastern Caribbean, is inhabited by three Iguana species: the Lesser Antillean iguana Iguana delicatissima, which is endemic to the northernmost islands of the Lesser Antilles, the introduced common iguana from South America, Iguana iguana iguana, represented also by the two newly described endemic subspecies Iguana iguana sanctaluciae from Saint Lucia and Iguana iguana insularis from Saint Vincent and the Grenadines, and Grenada, and the introduced Iguana rhinolopha from Central America. Drawing on both morphological and genetic data, this paper describes the Iguana populations from Saba and Montserrat as a new species, Iguana melanoderma. This species is recognized on the basis of the following combination of characteristics: private microsatellite alleles, unique mitochondrial ND4 haplotypes, a distinctive black spot between the eye and tympanum, a dorsal carpet pattern on juveniles and young adults, a darkening of body coloration with aging (except for the anterior part of the snout), a black dewlap, pink on the jowl, the high number of large tubercular nape scales, fewer than ten medium sized–triangular dewlap spikes, high dorsal spikes, and lack of horns on the snout. This new melanistic taxon is threatened by unsustainable harvesting (including for the pet trade) and both competition and hybridization from escaped or released invasive alien iguanas (I. iguana iguana and I. rhinolopha) from South and Central America, respectively. The authors call for action to conserve Iguana melanoderma in Saba and Montserrat and for further research to investigate its relationship to other melanistic iguanas from the Virgin Islands and coastal islands of Venezuela.

Keywords: Conservation Biology, Iguana, Lesser Antilles, microsatellites, mtDNA, new endemic species, phylogeny