Chaetotaxy and larval morphometry of Cercyon praetextatus (Say) and C. quisquilius (Linnaeus) (Coleoptera: Hydrophilidae: Sphaeridiinae) and their phylogenetic implications

Abstract

The primary and secondary chaetotaxy of the head capsule and head appendages of the three larval instars of Cercyon praetextatus (Say, 1825) and Cercyon quisquilius (Linnaeus, 1761) are described for the first time. Morphometric characters derived from the head capsule and mouthparts are also included, together with detailed illustrations of all characters. Morphology and chaetotaxy of these larvae is compared to that of Cercyon convexiusculus Stephens, 1829. Comparison of character states with other larvae of the tribes Megasternini, Coelostomatini, Protosternini and Shaeridiini confirms a well supported Megasternini, and a close relationship between Megasternini and Sphaeridiini.