Primary chaetotaxy of larval head of the hydrophiloid beetles

FIKACEK, M.; ARCHANGELSKY, M.; TORRES, P. L. M.

Izmir, Turkey

Congreso; VIIIth European Congress of Entomology; 2006

Primary chaetotaxy of the head of 13 species of Hydrophilidae (representing the tribes Hydrophilini, Anacaenini, Berosini, Laccobiini, Chaetarthriini, Coelostomatini, Megasternini and Sphaeridiini) as well as of larvae of the hydrophiloid families Helophoridae, Hydrochidae and Spercheidae was examined and homologized on the basis of the chaetotaxic nomenclature prepared for the first instar larva of Hydrobius fuscipes. Prelusive cladistic analyses based on three data partitions (head chaetotaxy of larva, non-chaetotaxic larval characters, and adult characters) and their combinations under different coding/ordering/weighting assumptions were performed and compared in order to evaluate impact of larval chaetotaxic characters for phylogenetic studies. Larval chaetotaxic characters were found adequate to define the phylogenetic relationships among tribes and subtribes and also very useful for identification of larvae. They seem to be, however, inadequate for defining of relationships among hydrophiloid families especially because of extensive modification of head chaetotaxy of Hydrochus and Spercheus. All three data partitions were found incongruent to each other and the incongruence seems to affect the results much more considerably than different coding/ordering/weighting assumptions. Comparison of tree topologies based on separate chaetotaxic and nonchaetotaxic larval data showed that the former corresponds with earlier published hypotheses in many aspects whereas the latter stands in contrast with them and seems to depend more on lifestyle of larva. In addition, the interpretation of some non-chaetotaxic characters of spercheid and hydrochid larvae was corrected on the basis of their chaetotaxy.