Skrjabinelazia rizzoi n. sp. (Nematoda: Seuratoidea) from a Sicilian lacertid, with comments on specific and biological diversity in the genus.

Skrjabinelazia rizzoi n. sp. (Seuratoidea), from Podarcis sicula captured at Cammarata, Agrigento Province, Sicily, is distinct from the 13 known species of the genus, including Skrjabinelazio sp. Rizzo from Catania. It is identified with the following set of characters: in the male, short spicules and gubernaculum, thin body; in the female, buccal cavity with a crown of leaflets, body cuticle without internal ornamentation, presence of cephalic and caudal vesicles, tail with a terminal digitiform spike 42-48 microm long. The morphology of the new species supports our previous hypothesis of two Skrjabinelazia lineages, one with spicules and one without spicules, respectively linked to Lacertidae and Gekkonidae. In Palearctic lacertids, five named species are presently known, S. taurica from Crimea (Ukraine), S. hoffmanni from Beijing (China), S. pyrenaica from Pyrenees (Spain), S. vozae from Cevennes (France), S. rizzoi from Agrigento Province, Sicily (Italy), but analysis of some published works suggests a greater diversity. S. rizzoi infection, found in April-May in 1/5 lizards, was recent with young females in the host's stomach and intestine, and males in the stomach. One female contained four membranous-shelled eggs. The two other females contained a few hatched infective larvae, membranous-shelled eggs with developing embryos and, unexpectedly at this early stage, a few thick-shelled divided eggs. As in several other Skrjabinelazia species, the progeny of S. rizzoi are adapted for intra-host suprainfection and inter-host transmission, but in this species the production of resistant eggs appears in very young females.