Further experimental proof of thelytokous parthenogenesis in oribatid mites (Acari: Oribatida: Desmonomata)

Abstract

Based on available sex-ratio data, and a few published laboratory proofs, it appears that thelytokous parthenogenesis is probably widespread in the oribatid mites. It is especially common in early-derivative taxa, such as the Desmonomata, where it seems to characterize whole families. Fifteen species of that group were proven capable of parthenogenesis by rearing immatures in groups or in isolation, and following the reproductive success of resulting adults; these include:Afronothrus incisivus, Allonothrus giganticus, Archegozetes longisetosus, Heminothrus ornatissimus, Nanhermannia dorsalis, Na. elegantula, Nothrus anauniensis, No. terminalis carolinae, Platynothrus banksi, P. biangulatus, P. bicarinatus, Trhypochthoniellus badius, Trhypochthoniellus excavatus, andTrhypochthonius americanus. Males are rare or absent in natural populations of each of these species. For three,P. biangulatus, Al. giganticus, andAr. longisetosus (two populations), thelytoky was proven by rearing parthenogenetically generated progeny. Existing evidence suggests that highly female-biased sex-ratios in the Desmonomata are a reliable indication of thelytokous capability, rather than reflecting an evolutionarily stable ratio of sexually reproducing species.