Melanism, Ring-Segments, and Associated Abnormalities in Female Hover Flies (Diptera-Syrphidae)

摘要

Various combinations of morphological abnormalities have been found in females of 23 species of Megasyrphus, Melangyna, Melanostoma, Metasyrphus, Platycheirus, Pyrophaena, Scaeva, and Spaerophoria (Syrphidae: Syrphinae). Cases of melanism in females associated with ring-like terminal abdominal segments, absence of ovaries, absence or reduction of spermathecae, irregularly arranged abdominal surface hairs, development of male secondary sexual characters, and reduced size are reviewed. The usefulness of these characters as objective means of recognizing invalid species based on aberrant specimens is discussed. Sphaerophoria cleoae Metcalf, described from abnormal females, is placed as a nomen dubium.