Testicular development and spermatogenesis in Calpodes ethlius Stoll (Hesperiidae, Lepidoptera)

Abstract

Some general features of the internal male reproductive system of Calpodes ethlius are described. The visibility of the testes through the transparent integument makes males distinguishable from hatching to the midpupal stage. The paired larval testes fuse at metamorphosis into a single adult testis. The major nongerminal cells of the testis consist of an outer capsule layer and an inner follicular layer which also extends inwards as septa separating the follicles. The cells of these two layers undergo extensive changes in shape and contents throughout larval life and during metamorphosis. Meiosis begins during the third larval instar with development of primary spermatocytes, followed by preparation for first meiotic division. Six spermatogonial and two meiotic divisions give rise to 256 sperm per cyst. Eight cyst cells are present in each cyst. Eupyrene spermatids first appear about 24 h before ecdysis into the last (fifth) larval instar, and apyrene spermatids in the early wax-secreting fifth larva. Both kinds of spermatids continue to be produced in approximately the same relative proportions throughout the pupal and adult stages.