Chromosomal analysis has revealed that what appeared to beHelophorus minutusF. from Tarifa (Spain, Provincia de Cadiz) is in fact a separate, sibling species, here described asH. calpensissp.n. Crossing maleH. calpensiswith femaleH. minutusfrom Surrey, England, resulted in embryos, most of which failed to hatch, and none of which survived beyond the second larval instar. Study of the chromosomes of hybrid embryos did not reveal obvious irregularities in chromosomal condensation, such as have been found in hybrids betweenH. minutusandH. paraminutusAngus, andH. lapponicusThorns, andH. paraminutus.