Osservazioni anatomiche sull’apparato genitale femminile in Ditrysia di 13 famiglie (Lepidoptera)

Abstract

ANATOMY OF THE FEMALE INTERNAL GENITALIA EXAMINED IN DITRYSIA OF 13 FAMILIES (LEPIDOPTERA)

Study deals with 29 species and is based on inseminated females. These were recognized from the presence of a very dense mass of sperm in their spermatheca. Spermatozoa did usually fill the receptacle and occupied also the duct of the spermathecal gland in some species; in Lycaenidae they were found also in the distal enlargement of the spermathecal duct. No trace of sperm was found in the spermatophore throughout, except in a minor number of Tortrix viridana females. In most families, copulatory pouch included only 2 regions: the corpus bursae and the copulatory channel. A third region, namely the caput bursae, was found in all Pieridae. Shape of the corpus bursae is usually supported by its content, which included one spherical or ellipsoid spermathophore; in Rhodometra sacraria (Geometridae) and Noctuidae, it does depend on the rigid integument of the bursa itself. Multiple spermathophore does seemingly arise from a single mating: examples of it are the snakelike item of Noctuidae and the superabundant spermatophore of Syntomis phegea (Syntomidae). Copulatory channel is entirely sclerotized and pipe-like in a minor number of species; elsewhere, it is supported by a sclerotized section, which surrounds the copulatory orifice. Signum was usually represented by a single sclerite; otherwise, it included either 2 symmetrical sclerites or 3 items in Syntomis phegea (Syntomidae). Although it is reported in the literature as the typical sclerite of Ditrysia, only 18 species out of 29 examined are provided with it. Seminal channel is present everywhere; it is lined by soft cuticle and bears a powerful muscular sheath; according to species, it connects to the copulatory channel as follows: (a) near the copulatory orifice; (b) at the distal end of the sclerotized channel; (c) within a membranous window of the latter. Spermathecal regions of every species are: (I) the duct; (II) the receptacle; (III) the gland. A further region, (IV) the inflatable diverticulum, was found in all Pieridae and in a minor number of species of other families. Spermathecal duct is always lined by membranous cuticle and is mechanically supported by a helical sclerite. This was misinterpreted as a second duct in the literature; according to species, is exhibits a very different number of spires (from 1 to 8) and is abruptly enlarged at its distal end in Lycaenidae. Receptacle has usually a shape simply elongated; sometimes, it is divided in two branches, and one the latter is able to inflate in Lycaena phleas and Satyrium spini (Lycaenidae). Spermathecal gland is heavily ramified only in Aporia crataegi (Pieridae), where its length is difficult to be entirely appreciated; elsewhere, it can be either very long (20 mm in Papilio machaon, Papilionidae) or less than 2,5 mm long; its intraspecific variability in very large in Maniola jurtina

(Satyridae), where length ranges from 2 up to 15 mm. Annexed sclerites of the copulatory orifice are a hemispheric item in Hypparchia statilinus (Satyridae) and a pair of tongs in Papilio machaon (Papilionidae). As already stated from the literature, abdomen of Polyommatus (Lycaenidae) exhibits a protrusile region, which supports the copulatory orifice at its apex.

Key words: inflating regions, sperm dislocation.

Viene studiato l’apparato genitale femminile in 29 specie di Ditrysia e messo a confronto con lo schema generale riportato dalla letteratura. La variabilità interspecifica riguarda in primo luogo la presenza/assenza delle parti note come bulla, caput bursae e signum e si esprime anche in ulteriori lineamenti anatomici della borsa copulatrice, del canale seminale e della spermateca. Viene rilevata qualche particolarità specie-specifica negli organi annessi all’apertura di copula e viene ridescritta la singolare regione esertile dell’addome dei Polyommatus (Lycaenidae). Lo studio si basa sull’esame di femmine inseminate, riconosciute come tali dalla presenza di una densa massa di sperma nella spermateca. Le stesse femmine recavano nella borsa copulatrice uno spermatoforo singolo o multiplo, che generalmente non conteneva tracce di spermatozoi.

Parole-chiave: regioni espandibili, dislocazione sperma.