Further challenges in taxonomic studies of Chironomidae (Insecta, Diptera) from morphological perspective

Contributions by many Japanese workers have greatly increased our knowledge of Japanese chironomid taxonomy over the last three decades. Currently, 1,206 chironomid species are recorded in Japan, but given the high diversity of natural environments, 2,000 species of chironomids are belived to be distributed in Japan. A detailed understanding of external morphological features in chironomids is one of the most important prerequisites for inferring their phylogenetic relationships. Concerning to the appendages on the gonocoxites of the hypopygia of the family Chironomidae, the term“volsellae” from Hymenoptera and named these appendages superor, inferior, and median volsellae are adopted by Sæther in 1980. Although his usage is reasonable based on the 1957 interpretation of Snodgrass, its applicability remains questionable because no distinct proof exists on whether the structures labeled as volsellae are homologous throughout the family. Instead, I recommended using terms proposed by Tokunaga in 1938 or those proposed in 1929 by Edwards for the subfamily Chironominae, as well as the neutral term accepted by Soponis in 1977 for the subfamily Orthocladiinae. Concerning the morphological terminology for the larval head, I follow Tokunaga’s interpretation in 1935.