Ochodaeus Dejean 1821: 56, 1995

Paulsen, M. J., 2007, Nomenclatural changes in the Nearctic Ochodaeinae and description of two new genera (Coleoptera: Scarabaeoidea: Ochodaeidae), Insecta Mundi 2007 (21), pp. 1-13 : 8-9

Ochodaeus Dejean 1821: 56

Remarks. Ochodaeus consists of approximately 60 Old World species, with 28 species in the Palearctic region ( López-Colón et al. 2006), some of which are not members of that genus based on propygidial structure. Nikolajev (2005) recently created the genus Notochodaeus (type species = O. maculatus Waterhouse ) based on the presence of a propygidial sulcus and differences in the metasternum and wing venation, although this is not reflected in the Palearctic catalog ( López-Colón et al. 2006). Similarly, I have not seen any New World species that should remain in Ochodaeus .

In North America, the only taxa (other than Codocera gnatho ) with an unmodified propygidium are O. sparsus LeConte and O. mandibularis Linell , and these appear to be conspecific. LeConte (1868) described O. sparsus from Cañon Blanco, NM. Linell (1896) subsequently described O. mandibularis from Winslow, AZ, comparing his new species with N. frontalis (LeConte) without mentioning O. sparsus . Both O. sparsus and O. mandibularis were considered valid by Fall (1909), and the species were distinguished by a “somewhat difficult mental character” and placement of the frontal horn, both of which might differ with size. Almost all specimens in collections were previously determined as O. mandibularis , and the name O. sparsus has become more or less disused. The holotype of O. sparsus (MCZ) is conspecific with the species currently treated as O. mandibularis . Although the type of O. mandibularis could not be located at the USNM (D. Furth, personal communication), there appears to be only one taxon present and O. mandibularis Linell is therefore a junior synonym of O. sparsus .

Although O. sparsus lacks a propygidial sulcus or tubercles, it has little else in common with Palearctic Ochodaeus , the type species of which is O. chrysomeloides (Schrank) . Ochodaeus sparsus is the only species of Nearctic ochodaeid examined in which the head is declivous behind the eyes, and the anterior marginal bead of the pronotum is correspondingly thickened and produced to contact the head; in the other Nearctic ochodaeids examined and O. chrysomeloides the anterior margin of the pronotum is simply convex. The stridulatory peg of the abdomen (see Fig. 4 ) is lacking in O. sparsus , and the antennal club has only nine antennomeres, not ten as in the type species of Ochodaeus . Due to these differences together with a complete lack of shared, derived characters that would unite it with Old World taxa, it is inappropriate to leave this species in the genus Ochodaeus , and a new genus is created for it.

Figures

Figure 1-4. Propygidia of Nearctic Ochodaeinae genera. Scale bars = 0.5 mm. 1) Unmodified propygidium of Cucochodaeus sparsus, with elytral apices evenly rounded. 2) Two tubercles present on apex of propygidium in Parochodaeus duplex, dentate elytral apices also shown. 3) Elongate propygidium with subparallel sulcus in Xenochodaeus simplex. 4) Short propygidium with trapezoidal sulcus in Neochodaeus praesidii, arrow indicates stridulatory peg.