The beetle fauna of Dominica, Lesser Antilles (Insecta: Coleoptera): Diversity and distribution

The beetle fauna of the island of Dominica is summarized. It is presently known to contain 269 genera, and 361 species (in 42 families), of which 347 are named at a species level. Of these, 62 species are endemic to the island. The other naturally occurring species number 262, and another 23 species are of such wide distribution that they have probably been accidentally introduced and distributed, at least in part, by human activities. Undoubtedly, the actual numbers of species on Dominica are many times higher than now reported. This highlights the poor level of knowledge of the beetles of Dominica and the Lesser Antilles in general. Of the species known to occur elsewhere, the largest numbers are shared with neighboring Guadeloupe (201), and then with South America (126), Puerto Rico (113), Cuba (107), and Mexico-Central America (108). The Antillean island chain probably represents the main avenue of natural overwater dispersal via intermediate stepping-stone islands. The distributional patterns of the species shared with Dominica and elsewhere in the Caribbean suggest stages in a dynamic taxon cycle of species origin, range expansion, distribution contraction, and re-speciation. 166 Volume 20, No. 3-4, September-December, 2006, INSECTA MUNDI butional patterns are of overwater dispersal, not a vicariant separation of prior continuous biotic distributions existing on a land bridge as in the model proposed by Iturralde-Vinent and MacPhee (1999). The beetle fauna. The beetles of the entire West Indies are still very poorly known. Blackwelder (19441957) summarized beetle data for the Neotropics, including the West Indies, as of the date of that publication. A recent summary of the Greater Antillean island of Cuba enumerates 2673 beetle species (Peck 2005). This compares to the 4675species known in the continental beetle fauna of Florida (Peck and Thomas 1998). The island of Hispaniola has 1466 known beetle species (Perez-Gelabert 2005). Tiny Guana Island in the eastern-most part of the Greater Antilles has received intensive attention by a variety of workers, and now has 405 documented beetle species (Valentine and Ivie 2005). Within the Lesser Antilles, Leng and Mutchler (1914, 1917), listed 705 species of beetles for the Guadeloupe island group from the work of Fleutiaux and Sallé (1890), Grouvelle (1902), and Grouvelle and Raffray (1908, 1912). The next best-known island may be St. Vincent, which was collected by Mr. H. H. Smith in 1887-1889 as a part of a project of the British Association for the Advancement of Science on the insects of the islands of “British West India” (Holland 1919). The beetles were described by several workers (e. g. Champion 1897), and Howard (1898) summarized the results of the project up to that time. Later references are in Blackwelder (1944-1957). For the islands of Grenada and the Grenadines, Woodruff et al. (1998) list 507 species of beetles (in 51 families). Bennett and Alam (1985) list the insect fauna of Barbados, with 239 species of beetles. Peck et al. (2002) list a very incompletely known fauna of 672 species of beetles from the continental shelf island of Tobago, northeast of Trinidad. The most important “recent” work on presenting a multi-family overview of the beetles of a part of the Lesser Antilles may be Fleutiaux et al. (1947) on the French Antilles, because of its scope and thoroughness. This was projected to be a set of volumes, but I am aware of only one volume being published. This covers 25 families of Polyphaga, including 118 genera and 207 species, with keys for generic and species identification, and many descriptions and fine illustrations. It estimates the entire beetle fauna of the French Antilles to be about 500-600 genera and about 1500 species. In the first summary compilation for Dominica, 57 beetle species were reported by Leng and Mutchler (1914, 1917) and then 123 species by Blackwelder (1944-1957) according to Spilman (1971). The first focused beetle survey of Dominica is that of Blackwelder (1943) as a part of his study of the Staphylinidae of the West Indies. He sampled in Dominica from 18 May to 12 July, 1936, with 26 sample stations, and found 26 species of Staphylinidae, excluding Aleocharinae. Spilman (1971) inaugurated a series of modern reviews of the beetles of Dominica, but, unfortunately, only a few papers on the beetle fauna have appeared since then (e. g., Cartwright and Chalumeau 1978). Chalumeau (1983a) and Chalumeau and Touroult (2005a) are summaries of their many studies on Scarabaeoidea and Cerambycidae of the Lesser Antilles, with a focus on Guadeloupe, Dominica, and Martinique. Anderson, D. M. 1965 Angus, G. F. Godman and Salvin (1884); Druce (1884) Ballou, H. A. Fisher (1932: 49) Becher, E. F. 1908; Champion (1917: 230) Blackwelder, R. E.July, 1936; Blackwelder (1943) Busch, A. August, 1905 Clarke, J. F. G. March, 1956; 1964