RESUMO
The Lesser Antilles, in the Eastern Caribbean, is inhabited by three Iguana species: the Lesser Antillean iguanaIguana 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.
RESUMO
The Lesser Antilles, in the Eastern Caribbean, were long considered to have only two species in the genus Iguana Laurenti 1768: the Lesser Antillean iguana Iguana delicatissima, which is endemic to parts of the Lesser Antilles, and the Common green iguana Iguana iguana, which also occurs throughout Central and South America. No subspecies are currently recognised. However, herpetologists and reptile collectors have pointed out strong physical differences between some of the island populations of Iguana iguana and those from the continent. Drawing on both morphological and genetic data, this paper describes two subspecies of the Common green iguana Iguana iguana from the southern Lesser Antilles, specifically the countries of Saint Lucia Iguana iguana sanctaluciae and Iguana iguana insularis from St Vincent the Grenadines, and Grenada. The form on the island of Saint Vincent has not been identified. The new subspecies are described based on the following unique combination of characters: Presence of high median and medium to small lateral horns on the snout; Small subtympanic plate not exceeding 20% of the eardrum size; Two or three scales of decreasing size anterior to the subtympanic plate; Fewer than ten small to medium triangular gular spikes; Medium sized dewlap; Low number of small to medium dispersed nuchal tubercles; Dark brown iris, with the white of the eye visible; Oval, prominent nostril; Short and relatively flat head; High dorsal spines; No swelling of the jowls in reproductively active males. Iguana iguana sanctaluciae has in adults vertical black stripes on body and tail and a black dewlap whereas Iguana iguana insularis is pale grey or creamy white in adults. Both subspecies are globally threatened by unsustainable hunting (including the pet trade) and by invasive alien species, including hybridization from invasive iguanas from South and Central America (I. iguana iguana and I. rhinolopha, considered here as full species) that have become established in all three countries. The authors call for stronger measures to conserve the remaining purebred Iguana i. insularis and Iguana i. sanctaluciae ssp. nov. throughout their ranges and for further research to identify other cryptic species and subspecies of Iguana in the Lesser Antilles.