Cybister Curtis, 1827

Figs 5, 7, 9, 10, 15-18, 30-35, 51, 52, 58, 59, 66, 72

Type species.

Dytiscus lateralis Fabricius, 1798.

Diagnosis.

Within Cybistrinae Cybister is characterized by the following: (1) a series of setae present along the posteroventral apical margin of the mesotarsomeres of males and pro- and mesotarsomeres of females (Fig. 5); (2) males with a single metatarsal claw, females with one or two, and if two, then the posterior claw small (some species with females dimorphic, some with a small posterior claw, others with only a single claw) (Figs 15-18); and (3) the medial margin of the lobes of the male abdominal sternite IX emarginate (Figs 51, 52). Larvae of Cybister (Neocybister) are unknown.

Distribution.

Cybister are found in all major biogeographic regions but are most diverse in the Afrotropical and Oriental regions, mainly in low latitudes. The group is not diverse in the Neotropical region where it is largely replaced in numbers of species and individuals by species previously in Megadytes (Megadytes) (most of these in a newly described genus, see below).

Phylogenetic relationships of Neotropical Cybister .

Cybister is the sister group to Megadytes as newly constituted (Figs 54, 76, see below). The Neotropical species of Cybister are in the subgenus Cybister (Neocybister) Miller, Bergsten & Whiting, 2007, which is restricted to the New World (Miller et al. 2007). This subgenus was resolved as sister group to all other Cybister in the analysis by Miller et al. (2007). It is resolved nested within Cybister here based on morphological data (Figs 75, 76), although previously examined molecular data (Miller et al. 2007) are not analyzed here. More investigation is needed. The two South American species are different from other Cybister in having (1) females always with a second, rudimentary posterior claw (Figs 15-18), (2) the medial margin of the gonocoxa distinctly emarginate (Figs 58, 59), and (3) the apex of the ventral sclerite of the male median lobe distinctly bifid (Figs 31, 34).