The anatomy, histology, and physiology of the reproductive systems of Lytta nuttalli Say (Coleoptera: Meloidae). I. The internal genitalia.

Abstract

The anatomy and histology of the male and female internal genitalia of Lytta nuttalli Say and the functions of the various organs during copulation and oviposition are described. In addition to the ovaries, lateral and common oviducts, and vagina, the female system includes a spermatophoral receptacle, accessory gland, and spermatheca. The most distinctive feature is the voluminous spermatophoral receptacle, which seems to be homologous with the bursa copulatrix of other Coleoptera, but serves to store and digest old spermatophores. The accessory gland is not a colleterial gland, but instead produces materials that probably are involved in the transfer of the spermatozoa into the spermatheca. The epithelia of the calyces and oviducts secrete the frothy, mucilaginous material that coats the eggs at oviposition. In the absence of a separate spermathecal gland, the epithelium of the spermatheca apparently has taken over its functions. The ovaries contain several hundred ovarioles of the telotrophic type. The chief structures of the male system are three pairs of accessory glands plus the testes, vasa deferentia, and ejaculatory duct. Each vas deferens consists of an enlarged portion that serves as an additional accessory gland and a narrow part, which is the seminal vesicle. Materials produced in the three pairs of accessory glands and the glandular portions of the vasa deferentia are used in spermatophore formation. The testes contain several hundred short sperm tubes similar to those of other insects. The arrangement, form, and functions of the internal reproductive organs of L. nuttalli are compared with those of other insects. Observations made on the reproductive systems of four species of Epicauta are also discussed in this context.