Berlesia, Canestrini, 1884

Lindquist, Evert E., Oconnor, Barry M., Shaw, Matthew D. & Sidorchuk, Ekaterina A., 2020, Review of the genera Berlesia Canestrini, 1884, and Katydiseius Fain & Lukoschus 1983, the subfamily Katydiseiinae Fain & Lukoschus, 1983, and their family group relationships (Acari: Mesostigmata: Gamasina), with description of three new species parasitic on gryllacridid crickets (Orthoptera), Zootaxa 4857 (1), pp. 5-70 : 35

Berlesia and Katydiseius as separate genera

The above descriptions, presenting morphological similarities as well as distinctions between Berlesia and Katydiseius , may indicate that the latter taxon is a derivative subset of the former, such that it could be considered as either a subgenus or as fully congeneric with it. A critical missing piece of the puzzle is any knowledge of the male of the monotypic Katydiseius . However, Fain & Lukoschus (1983) described the type species as having a free-living larva with chelicerae nearly as fully developed as in the protonymph, whose chelicerae in turn were not indicated to differ from the deutonymph. A fully developmental ontogenetic sequence of instars may in turn suggest other differences in behavior, including copulation. The life history of species of Berlesia is compacted/shortened, by way of nymphipary and by male copulation with females not yet eclosed from their deutonymphal skins, which may be facilitated by an extremely elongated spermatodactyl of the male. Based on the presence of a free-living and apparently functional larva, such life history compaction is not indicated in Katydiseius nadchatrami . Indeed, the parasitic association of Berlesia species with gryllacridid crickets may differ considerably from that of K. nadchatrami with pseudophylline tettigoniid crickets, such that perhaps males with extremely elongated spermatodactyls adapted for mating with pharate females should not be assumed for the latter. Note also that the deutonymph of K. nadchatrami has an entire dorsal shield like that of the female, rather than the unusual, apomorphic condition of that shield being divided in the deutonymph but entire in the adult of Berlesia species. Unlike that of Berlesia spp., the deutonymph of K. nadchatrami was not noted to have more distinctly developed claws than in other instars; this is notable as it may indicate a difference in phoresy, or even more interestingly in copulatory behavior (see ontogenetic considerations, below). The bulbiform subcapitular and coxal setae in female Berlesia are also apomorphic with respect to the simple form of those setae in Katydiseius . Each genus is diagnosed above with unique apomorphies, with the presence of other, shared apomorphies from which we infer a sister relationship.