EVOLUTION OF AEDEAGAL PARAMERES OF ALEOCHARINE STAPHYLINIDS (COLEOPTERA: STAPHYLINIDAE: ALEOCHARINAE)

Abstract

AbstractThe structure of the parameres (lateral lobes) of aleocharine aedeagi was examined in detail, with special attention to the basal lineages. Paramere structure was compared in the context of a hypothesis of phylogeny of the basal lineages of the Aleocharinae and the Tachyporine Group of subfamilies. The ancestor of all contemporary aleocharines had parameres with the following characteristics: dorsobasal and ventrobasal lobes of more similar size than in extant higher aleocharines; dorsobasal lobe (condylite) continuous with distal lobe (not articulated); a striated velum (velar sac), extended from near the base of the dorsobasal lobe to near the apex of the distal lobe and derived from the dorsal surface of the distal lobe; distal arm entire, without articulations or independently movable parts; and four apical setae on the distal lobe, probably with the most apical and basal ones directed mediad and the two medial ones directed more-or-less laterad. In addition, each paramere was articulated with a separate condyle of the median lobe of the aedeagus near the middle of the condylite of the paramere, and the apices of the dorsobasal lobes of the two parameres articulated with each other substantially distal to the articulation with the median lobe of the aedeagus. The most parsimonious resolution of paramere evolution suggests that aleocharine parameres were derived from structures similar to those found in Trichophyinae, Phloeocharinae, and Olisthaerinae and that they are not de novo structures. Hypotheses about homologous regions between aleocharine parameres and those of these latter three groups are suggested.