Redescription of Leuctra costai Aubert, 1953 and Considerations about its Morphological Variability (Plecoptera, Leuctridae)

The male of Leuctra costai (Aubert, 1953) is redescribed. In all specimens studied, we noted the presence of two sclerotized processes in the tenth urosternite (not reported in any other Leuctra species) and the presence of lateral sclerotized processes on the last four abdominal segments (previously cited only in Leuctra moreae, Zwick, 1978). These characters, which were not mentioned nor illustrated in the original description and never quoted in papers where this species was cited, can be of importance from the systematic and phylogenetic points of view. Moreover the existence of morphological variability, i.e., the presence in a southern Italian population of two additional sclerotized processes on the fifth urotergite, is reported and discussed.