A comparative morphological study of the genital tube in some hydrophilid species (Coleoptera: Hydrophilidae) with a discussion on the importance of the internal genital characters in phylogenetic studies

Abstract

The morphology of internal genital tubes in 52 species of water scavenger beetles (Col., Hydrophilidae) are investigated based on personal observation of 22 species and collecting data of formerly published studies of 30 species. In males, morphological differences are observed in generic level and in the structures of the testes. In females, morphological variations are detected in several features in different taxonomic levels: 1. connection position of spermathecal duct to bursa copulatrix, 2. length of spermathecal duct, 3. size and shape of spermathecal gland, 4. size and shape of spermathecal bulb, 5. connection of spermatheca and spermathecal gland with spermathecal bulb, and 6. presence or absence of sclerotized spine inside the membranous wall of the bursa. The length of the spermathecal duct is highly variable across the species, while, the connections of the spermathecal duct and gland with the bulb remain constant in tribe or subfamily level. The importance of using the female genital tube characters in phylogenetic analysis is discussed along with investigating the CI and RI of the genital characters of Sternolophus species in a data set of its morphological characters.

Keywords

• hydrophilidae
• comparative study
• genital tube features
• female genital morphology