PHYLOGENY AND BIOGEOGRAPHY OF LONGIDORUS (NEMATODA: LONGIDORIDAE) IN EUROMEDITERRANEA

Abstract

Patterns of distribution of a monophyletic branch of Longidorus species in previously established chorological units (CUs) of Euromediterranea, provide a basis for historical biogeography and a phylogenetic hypothesis of the species. The centre of distribution of each Longidorus species within each CU was estimated by statistical methods to correct the apochoric component of the species due to expansion. CUs are compared geographically and faunistically (with respect to Longidorus composition). Distribution graph matrix analysis, applied to define the direction of the connections between CUs, did not establish which endemic species is most ancestral; rather, hypotheses of ancestry and polarity of multistate characters were tested by a morphologically-based cladogram congruent with the distribution graph. Longidorus carpetanensis is supported as an outgroup of all the other species. The results suggest that vicariant biogeography can resolve some aspects of the current pattern of Longidorus distribution and speciation origin, but that a dispersalist model is a primary explanation for large groups of Longidorus species in Euromediteranea.