Descriptions of the Male and Female Genitalia of Phanaeus (Macleay) (Scarabaeidae: Scarabaeinae): the Vindex Species Group

Illustrated descriptions of the male genitalia and notes on the spermathecae are provided for the Phanaeus vindex species group: P. vindex (Macleay), P. difformis (LeConte), and P. igneus (Macleay). These represent the first descriptions of the internal sac (aedeagus) for these species. Examination of the genital capsule (i.e., phallobase and parameres) and the sclerites within the internal sac (aedeagus) revealed only slight differences in shape and sclerotization.

No differences were observed among the spermathecae of the three species. The dung beetle genus Phanaeus Macleay consists of 13 species groups found in the New World (Edmonds 1994). The vindex species group can be distinguished from closely related groups by the sculpturing of the elytra.

Several observations of biology, life cycle, feeding habits and nesting behavior of these beetles have been reported, but the only studies of the male internal sac of Phanaeus is that of Zunino (1985) who in his examination of the taxonomic relationships of the Phanaeina examined an unidentified Phanaeus. Other studies of the male genitalia of Phanaeus include; Edmonds (1972; genital capsule of P. vindex); Blume and Aga (1978; genital capsule of P. vindex and P. difformis); and Howden and Young (1981; genital capsule of P. beltianus).

The spermatheca, on the other hand, has been examined in several species of Phanaeus, but not difformis, vindex or igneus. Species for which the spermatheca has been described or illustrated include; P. daphnis and P. mexicanus (Halffter and Lopez 1977), P. daphnis (Lopez-Guerrero and Halffter 1982), and P. quadridens (Marchisio 1982 –83). In addition, the following species were examined by Lopez-Guerrero and Halffter (2002) in a study on the evolution of the spermatheca in Scarabaeoidea; P. mexicanus, P. daphnis, P. demon, P. sallei, P. palliatus, P. quadridens, P. tridens, P. endymion, P. guatemalensis, P. halffterorum.

In general, these authors found the spermatheca to be very similar in all species of Phanaeus examined. The purpose of this paper is to present the first detailed morphology of the external genitalia of three closely related species of Phanaeus found in the United States. In addition, the discussion includes comments concerning structure of the male genital capsule, the internal sac, and the spermatheca.

Materials and

Methods

In this study I used dried museum specimens of Phanaeus from the National Museum of Natural History as well as specimens from the personal collection of W. D. Edmonds. Locality data are listed below.