Chromosomal and distributional insights into the cytoforms of Simulium ruficorne (Diptera: Simuliidae)

Analysis of the giant polytene chromosomes from larvae collected at four locations near the distributional periphery of Simulium ruficorne Macquart revealed a new cytoform, “E”, from Mauritius and a new country record, Greece (Crete), for Europe. Samples from Crete and Israel represent the widespread cytoform A, specifically cytoform A1. With the discovery of cytoform E, about 215 km from the type locality of S. ruficorne on Réunion, the new chromosomal insights draw us closer to the possibility of recognizing distinct species within S. ruficorne. Of the six cytoforms of S. ruficorne, E is chromosomally most similar to cytoform A1/A2. The discovery of S. ruficorne breeding in Crete mirrors previous recent discoveries of breeding populations on other islands, such as Madeira and Majorca. We suggest that females of S. ruficorne are highly adapted to finding suitable habitat for the preimaginal stages, often small, intermittent, flows, and have persisted undetected on these islands for long periods of time, perhaps aided by resistant eggs.