Probable origins of the West Indian Trichoptera and Odonata faunas

Abstract

Upon analysis of the distribution of the West Indian Trichoptera and Odonata the following patterns become clear. The Trichoptera are very highly endemic, over 80% of the species being known from only one island, whereas the Odonata are much less so with only 15% of the species apparently restricted to one island. There does seem to be a correlation between the size of the organism as well as its ecological tolerance and the area it occupies. The small Hydroptilidae and the largest dragonflies, and those species the most ecologically tolerant are the most widely distributed.

The Greater Antilles support a distinct fauna that appears to have been isolated for a long time and which shows three relationships, as follows: 1. a North American element which appears to be rather minor; 2. a Neotropical element, closely related to the fauna of Mexico and Central America, which is the overwhelming percentage; and 3. a very small element that is related to equatorial or southern Africa.

The Lesser Antilles also has a distinct fauna, although seemingly less highly endemic than that of the Greater Antilles. There is a small element that may be called Antillean, but in general the fauna is quite different from that of the Greater Antilles. The primary relationship is with northern South America, from which a part of the fauna seems to have been derived by dispersion.

The entire picture agrees well with the Vicariance Model of Biogeography as proposed by CROIZAT and specifically as developed by ROSEN for the West Indies.