Ctenodactylini

Erwin, Terry L. & Medina, Raul F., 2003, The Neotropical species Askalaphium depressum (Bates): Larval description, first diagnosis and illustrations of immature Ctenodactylini, with natural history notes on the genus and tribe (Coleoptera: Carabidae), Zootaxa 273, pp. 1-15 : 14

Characteristics of Ctenodactylini

Although van Emden (1948) mixed attributes of two unrelated tribes, Odacanthini and Ctenodactylini , some features of the latter may be extracted from his descriptions. His observations of members of the genus Leptotrachelus contain the following which we also found in larvae of A. depressum : epicranial suture short; cervical groove and keel present; maxilla with inner lobe present; neck not severely constricted; urogomphi nodal, yet not segmented. We located the collection of L. dorsalis larvae that van Emden studied (collected at Oxford, Indiana) in the NMNH, however, they are not in very good condition. We confirm his observations and add that second and third instars lack a pencillus and the terebral blade is serrate, but refrain from making a more detailed comparison until better specimens are discovered in future field work. These observations are at least a beginning in our understanding of the structural features of the larval stages for the carabid tribe Ctenodactylini . There are some poorly preserved specimens of Odacanta melanura Linneaus in the NMNH collection, as well, and we studied these as well as possible considering their condition. These specimens differ from ctenodactyline larvae in that the mandible has a single seta pensillus and the maxilla lacks an inner lobe, other features are not discernible.

The postulated commensal association with monocotyledonous plants and larvae of a genus of chrysomelids provides an additional characteristic feature of ctenodactylines. Species representing other genera of the this tribe are known to occur commonly as adults on the culms of marsh grasses such as Panicum dichotomiflorum ( Leptotrachelus dorsalis: Steiner 1984 ) in Maryland, USA, and Paspalum sp. ( Leptotrachelus spp.: Erwin 1991) in the western Amazon Basin. Undescribed larvae of some genera of ctenodactylines were also found in the rotten stems and leaf axils of species of the plant genera Heliconia and Calathea in low wet places. Further discovery is necessary and subsequent documentation is required to define more accurately the Ctenodactylini , and to explore the patterns that must link these beetles evolutionarily and ecologically to the plants on which they live and the food which they eat.