Evolution and taxonomic significance of the copulatory apparatus in Ensifera (Orthoptera). Part 2: Male genitalia in Grylloidea

Abstract

In the superfamily Grylloidea, the main trends in the evolution of the copulatory apparatus were probably connected with the transformation of simple membranous (hagloid) genitalia, characteristic of ancient groups of Ensifera, into a complicated organ with highly specialized sclerites for fixation of the female during copulation. This evolutionary process was probably accompanied by partial reduction and disappearance of paraproctal hooks or other external abdominal processes which may have been used by these ancient groups for female fixation. Sclerites in the male genitalia of Grylloidea appeared independently not less than four times: in Gryllotalpidae, Myrmecophilidae, Gryllidae and Mogoplistidae. This hypothesis, proposed by Gorochov in 1984, was one of the reasons for division of the recent Grylloidea into four families. Each of the first three families acquired sclerites in the male genitalia once, whereas Mogoplistidae possibly acquired them more than once: male genitalia of the tribe Mogoplistini are of the hagloid type, membranous; in most genera of Arachnocephalini (Mogoplistinae), in Pseudomogoplistes (Mogoplistinae) and in Malgasiinae, male genitalia have three types of sclerites which could have also appeared independently. Moreover, many sclerites of the male genitalia in Grylloidea are formed independently and have significant convergent similarity; this is why the nomenclature of male genital structures based partly on their function and position but not exclusively on their homology is simpler and much more suitable for descriptions and morphological investigations. This nomenclature is considered here.