Larval morphology and phylogenetic position ofHorelophopsis hanseniSatô et Yoshitomi (Coleoptera, Hydrophilidae, Horelophopsinae) : Larva of the hydrophilid subfamily Horelophopsinae

As a first attempt to use molecular data to resolve the relationships between the four suborders of lice and within the suborder Ischnocera, we sequenced a 347-bp fragment of the elongation factor 1alpha gene of 127 lice (Insecta: Phthiraptera) as well as outgroup taxa from the order Psocoptera. A number of well-supported monophyletic groups were found but the relationships among many of these groups could not be resolved. While it is probable that multiple substitutions at high divergences and ancient radiation over a short period of time have contributed to the problem, we attribute most of this lack of resolution to the high ratio of taxa to characters. Nevertheless, the sequence data unequivocally support a number of important relationships that are at variance with the conclusions of morphological taxonomy. These include the sister group relationship of Chelopistes and Oxylipeurus, two lice occupying different ecological niches on the same host, which have previously been assigned to different families. These results provide evidence in support of the hypothesis that lice have speciated in situ on the host in response to niche specialization and that this has given rise to convergent morphologies in the lice of different host groups which share similar ecological niches. We discuss our attempts to overcome the limitations of this large data set, including the use of leaf stability analysis, a new method for analyzing the stability of taxa in a phylogenetic tree, and examine a number of hypotheses of relationships based on both traditional taxonomy and host associations. Copyright 2001 Academic Press.

The Staphyliniformia is one of the most diverse lineages of Coleoptera, with representatives occupying every conceivable non-marine niche. Phylogenetic relationships among its varied families and lower taxa have defied resolution. The problem has been further complicated by the recent suggestion that another major coleopteran series, Scarabaeiformia, is derived from within it. Here we present the first phylogenetic analyses, based on 18S rDNA sequences and morphological data, to explicitly examine this possibility. Thorough evaluation of alternative alignments and tree construction methods support the contention that Scarabaeiformia is derived from within Staphyliniformia. Though the analyses yielded strong support for few family level groupings within the expanded Staphyliniformia, they conclusively support a close relationship between Hydraenidae and Ptiliidae, which has often been debated. The primary factor hindering additional resolution appears to be the inconsistent rate of divergence in 18S among these taxa.