Iguana iguana subsp. insularis Breuil & Vuillaume & Schikorski & Krauss & Morton & Haynes & Daltry & Corry & Gaymes & Gaymes & Bech & Jelić & Grandjean 2019, nov. ssp.
Creators: name: Breuil, Michel
name: Vuillaume, Barbara
name: Schikorski, David
name: Krauss, Ulrike
name: Morton, Matthew N.
name: Haynes, Pius
name: Daltry, Jennifer C.
name: Corry, Elizabeth
name: Gaymes, Glenroy
name: Gaymes, Joanne
name: Bech, Nicolas
name: Jelić, Mišel
name: Grandjean, Frédéric
Publisher: name: Zenodo
Year: 2019
Subjects: Biodiversity
Taxonomy
Animalia
Chordata
Reptilia
Squamata
Iguanidae
Iguana
Iguana iguana
Iguana iguana insularis

description: Iguana iguana insularis nov. ssp.
Grenadines horned iguana, pink rhino iguana
Figs. 3–6.
Holotype. The holotype of Iguana iguana insularis housed in MCZ under the numbers X-17620/R-79057 (Fig. 3). This specimen was caught by James Lazell on Bequia, St Vincent & the Grenadines (10 April 1964).
Sex: Undetermined.
Age: Young, possibly 2 years old, based on its size.
Morphological measurements: Total length: 51.5 cm, SVL: 13.5 cm, tail length: 38 cm. Height and width of the left subtympanic plate: 3.2 mm, 4.3 mm.
Meristics: Number of gular spikes, 5 medium + 2 small. Number of dorsal spikes to cloaca: 54 ± 1.
Paratypes. Two other young specimens MCZ X-17619/R-79056 and X-17621/R-79058) from the same location and the same collector.
Diagnosis of Iguana iguana insularis (Figs 4, 5). We define the typical morphology of this new taxon based on our own observations on both adults and juvenile specimens on Palm and Union Islands (St Vincent & the Grenadines), complemented by the specimens from MCZ R-79056-57-58 collected on Bequia (also in St Vincent & the Grenadines) and R-79747 from Sandy Bay, Grenada. The latter four are young individuals with SVL from 128 mm to 135 mm, and thus lack some details specific to adults.
The iguanas from the Grenada Bank, including the Grenadines, are characterised by the following association of characters in adults compared with iguanas from Saint Lucia (I. iguana sanctaluciae ssp. nov., see below).
– In most old adults (both males and females), the green colouration and black bands fade to an almost uniform light cream to nearly white, except on the posterior end of the tail where the black banding persists;
– In old adults, the head is nearly light cream to white;
– The dewlap is predominantly white but may have some black scales;
– There are no black margins on the subtympanic plate and on the sublabial scales;
– The snout has 2 to 5 median horns (usually 3 or 4) and 2 to 6 less developed lateral horns on each side;
– The horns may or may not remain black throughout the animal’s life;
– There are light yellow scales on the head and on the dewlap in old adults;
– The tips of the dorsal spikes of mature adults during the breeding season are light yellow to light orange;
– The anterior part of the dewlap is rounded.
Size. The largest purebred I. iguana insularis measured by the authors had an SVL of 45 cm (IGU77, an adult male on Palm Island, Fig. 4). Its tail was incomplete.
Another large individual fitting the morphology of this subspecies (but not genetically tested) on Petit Bateau had a total length of 136 cm.
Geographical distribution (Fig. 6). Of the c. 30 islands of Grenada Bank, including the Grenadine islands and the main island of Grenada, 26 have been reported to have iguanas (Henderson & Powell 2018). The entire bank is inferred to have been originally inhabited by I. iguana insularis but morphological (e.g. Henderson & Powell 2018, photograph p. 50) and genetic data indicate that several islands, including the main island of Grenada, have had incursions of iguanas from South American and/or Central American lineages.
From our collection of photographs of specimens captured by the authors and obtained from internet searches, it is clear that most Grenadine islands still have the indigenous white, horned and more or less black-banded phenotype, but there is the Central America phenotype with various hybrids among them that make it difficult to confirm which islands still have purebred populations of this subspecies. Further genetic testing is required to accurately map the present distribution of I. iguana insularis and invasive iguanas.
Etymology. The subspecific name refers to the numerous islands in the southern Lesser Antilles where the new subspecies lives.
description: Published as part of Breuil, Michel, Vuillaume, Barbara, Schikorski, David, Krauss, Ulrike, Morton, Matthew N., Haynes, Pius, Daltry, Jennifer C., Corry, Elizabeth, Gaymes, Glenroy, Gaymes, Joanne, Bech, Nicolas, Jelić, Mišel & Grandjean, Frédéric, 2019, 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), pp. 201-232 in Zootaxa 4608 (2) on pages 208-212, DOI: 10.11646/zootaxa.4608.2.1, http://zenodo.org/record/3055184