My work on Dytiscidae (see fig. 1-4 below) includes the entire group with a large amount of species-level taxonomy as well as higher-level cladistic phylogenetics. I have described about 50 species and revised or otherwise treated 10 genera and species-groups.

My primary area of interest for alpha taxonomy is the neotropics which represents the greatest species and phylogenetic diversity of any bioregion. My interest in higher-level phylogenetics is based mainly in the subfamilies Hydroporinae and Dytiscinae. This last group represents one of the best examples of sexual conflict across a larger group, and I have ongoing research on the evolution of this sexual selection scenario in this group as it relates to the phylogeny. Females appear to vigorously resist male mating attempts, possibly because of prohibitive costs of multiple matings.

Some members of the Dytiscinae have males bearing sucker-setae on the protarsi which are used to adhere to the smooth dorsal surfaces of females prior to mating (e.g. Fig. 3 below), apparently helping males to hang on during the female resistance. However, females in some groups have a variety of surface sculpturing which is quite dramatic and appears to inhibit the ability of the male to adhere (e.g. Figs 4-6 below).

Thus there appears to have been an evolutionary arms race between the sexes as each seeks to gain greater control over the decision to mate. This scenario is evident in the phylogeny (see Miller 2003).

My work on this is partly a collaboration with Johannes Bergsten (Umeå University). We are currently working on a more comprehensive phylogeny of this group to study certain finer details of this scenario. We are also working on comprehensive phylogenies of a couple of genera and tribes within this group, each of which appear to have evolved different strategies in response to the pressures of this type of sexual selection.

Current projects in Dytiscidae:

• Revision of the tribe Vatellini for the New World
• Revision of the genus Laccophilus for the Neotropical region
• Revision of the genus Celina.
• Phylogenetic analysis of Hydroporinae to place the genus Peschetius (in collaboration with Bill Wolfe and Olof Biström)
• Collaborative work on African Cybister and Laccophilus with Bill Wolfe
• Description of several species from Peru
• Revisionary and phylogenetic work on Acilius (in collaboration with Johannes Bergsten)
• Phylogenetic and evolutionary work on Dytiscinae emphasizing sexual conflict (in collaboration with Johannes Bergsten)

Fig. 1: Thermonectus marmoratus (Gray)	Fig. 4: Dytiscus marginalis, L.; male, female, and female dorsal sculpture
Fig. 2: Acilius sylvanus, Hilsenhoff	Fig. 5: Hyderodes shuckardi Hope; male, female, and female dorsal sculpture
Fig. 3: Dytiscus marginalis, L.; male, ventral surface showing expanded protarsi and sucker-setae	Fig. 6: sulcatus (L.); male, female, and female dorsal sculpture