The Digestive and Reproductive Systems of the Meloidae (Coleoptera) and Their Significance in the Classification of the Family1

Abstract

The digestive and reproductive systems of 46 meloid species, representing 32 genera from North America, Europe, North Africa, and India, were studied, and a subfamily and tribal system based on these internal systems is proposed. The fore-gut of the meloids includes a fairly well-developed esophagus, a simple proventriculus, and a stomodaeal or cardiac valve. There is no crop. The stomodaeal intima shows definite longitudinal and irregularly arranged internal folds; in addition, it exhibits other modifications such as transverse corrugations, emarginate, transversely oriented {-shaped and dotlike thickenings, and polygonal patterns. The spines on the intima may be scattered or may follow a definite arrangement. The size, number, and position of the lobes of the stomodaeal valve vary greatly. The mid-gut (ventriculus) is well developed; it is transversely wrinkled and granulate in Meloinae and rather smooth in Nemognathinae. The hind-gut (proctodaeum) usually is well developed. There are 6 cryptonephridial malpighian tubules, which may arise separately or in pairs; they are attached posteriorly either on the distal portion of the ileum or on the inner bend of the posterior flexure of the hind-gut; in some groups these tubules have basal pouches. The spermathecal capsule of the female reproductive system exhibits various modifications in size and shape; also, it may have a well-developed tubular or vesicular basal diverticulum, or it may merely show a basal swelling. A single, tubular or vesicular accessory gland is always present. The vagina is variable in length and width, but was not found to have taxonomic significance. In the male system, the testes are spherical or oval; they are much enlarged in the Nemognathinae. The vesicula seminalis varies in size; it is usually smooth externally but is transversely wrinkled in Lyttini. The first of the 3 pairs of accessory glands is spherically or ovally coiled or irregularly convoluted; the second pair (usually the smallest) arises posterior to it; the third pair (usually the largest) is variously convoluted. The ejaculatory duct was found frequently to be curved or looped and to be of differing widths; however, this structure was not used as a character in classification. The present study recognizes 2 subfamilies, Meloinae and Nemognathinae. The former includes the tribes Mylabrini, Cerocomini, Eupomphini, Epicautini, Pyrotini, Lyttini, Meloini, and Tetraonychini. The Nemognathinae contains the tribes Horiini, Apalini, and Nemognathini. Of all the tribes studied, the Eupomphini shows the greatest variation; several of its genera may eventually have to be assigned elsewhere. The genus Linsleya is removed from the Epicautini and tenatatively placed in the Lyttini. The Old World genera Cabalia and Sybaris have, with some question, been retained in the Lyttini although they lack the well-developed spermathecal diverticulum which has been considered an important character of this tribe.