A story of nasal horns: two new subspecies of Iguana Laurenti, 1768 (Squamata, Iguanidae) in Saint Lucia, St Vincent & the Grenadines, and Grenada (southern Lesser Antilles)

Abstract

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.

Painted black: Iguana melanoderma (Reptilia, Squamata, Iguanidae) a new melanistic endemic species from Saba and Montserrat islands (Lesser Antilles)

“…Morphological studies of the St. Lucia Iguana, belonging to the third group of Lazell (1973), indicated this iguana population is very different from the horned iguana population from Central America (Breuil , 2016. Breuil et al (2019) showed with genetic (microsatellites, mtDNA) and morphological studies that this third group comprises two subspecies, Iguana iguana sanctaluciae, endemic to Saint Lucia and I. iguana insularis, endemic to the Grenadine Bank. Lazell (1973) in the 1960s and new taxonomic proposition.…”

“…Now, alien iguanas are present and breed on every bank (van den Burg et al 2018b). The southern group is now considered to support two subspecies Iguana iguana insularis and Iguana iguana sanctaluciae (Breuil et al 2019). The northern group is considered here as a new species.…”

Illegal trade of morphologically distinct populations prior to taxonomic assessment and elevation, with recommendations for future prevention

“…1), occurs throughout most of Central-and South America, including a number of Caribbean islands (Bock, Malone, Knapp, Aparicio, & Avila-Pires, 2019). Despite this species' wide native distribution and identified phenotypic and genetic differences (Lazell, 1973;Malone, & Davis, 2004), extensive phylogeographic and phenotypic diversity research only recently commenced (Breuil, 95 2013;Stephen, Reynoso, Collett, & Hasbun, 2013;Breuil et al, 2019). However, a thorough study on range-wide phenotypic variation is still lacking.…”

“…Besides native populations, numerous established alien populations are known, having originated primarily in the pet-trade (Falcón, Ackerman, & Daehler, 2012;van den Burg, van Belleghem, & De Jesús Villanueva, 2020). In fact, the pet trade has been identified as a threat to local mainland populations due to the unsustainable harvest of wild 100 animals (Stephen, Pasachnik, Reuter, Mosig & Ruyle, 2011), and despite an allowable and robust legal trade under CITES, trafficking of the species has been recorded from several countries in Central America Caribbean islands Noseworthy, 2017;Breuil et al, 2019). to scientifically establish the Saba Black Iguana as a distinct subspecies of the Green Iguana (Iguana iguana), only found on Saba".…”

Testing for hybridisation of the Critically Endangered Iguana delicatissima on Anguilla to inform conservation efforts

“…Two species of Iguana are currently recognised: the Critically Endangered Lesser Antillean iguana Iguana delicatissima (van den Burg et al 2018), the green or common iguana Iguana iguana (classified by IUCN as Least Concern Bock 2018). The latter includes several native subspecies, including Iguana iguana insularis (first described and evaluated as Vulnerable by Breuil et al 2019) and Iguana iguana sanctaluciae (described and evaluated as Critically Endangered, Breuil et al 2019).…”