Dettagli anatomici dei genitali interni in Melanthrips fuscus (Sulzer) e altri tisanotteri

Abstract

SOME ANATOMICAL DETAILS OF THE INTERNAL GENITALIA IN MelAnthrips fuscus (SULZER) AND OTHER THRIPS

Internal genitalia were examined in males and/or females of 20 species of Terebrantia and 6 species of Tubulifera; they were extracted to live individuals anaesthetized with ethyl-acetate vapour and dissected in saline 0,9%. Spermatozoa were set free by squashing testes and/or spermatheca on slides in the same solution.

Besides the usual four-paired ovarioles, females of M. fuscus possess the spermatheca and an unpaired ovipositor gland. Spermatheca includes: a spherical receptacle, a short duct and a small basal sclerite. Receptacle is nearly 50 μm large and is screened by bright-orange fat-body. The ovipositor gland includes: a large reservoir and a short duct. The latter connects to the apical bulb of a canal belonging to the first pair of valvae. Males of M. fuscus exhibit: two clavate testes, each with a short deferent, and a single pair of accessory glands. A violaceous fat-body screen protects testes.

The following major interspecific variations were found throughout: (a) receptacle is very large (as many as 120 μm in diameter) in Aeolothrips tenuicornis; (b) receptacle is able to inflate (up to nearly 1.000 μm in length) in Compsothrips albosignatus; (c) spermathecal duct of C. albosignatus bears a pumping and/or valvular device; (d) all Tubulifera lack ovipositor gland; (e) duct of this gland is exceedingly long (700-1.000 μm) in some Terebrantia; (f) males of Tubulifera possess 2 pairs of accessory glands; (g) deferents of Tubulifera are very long.

Usually, receptacle of Terebrantia stores a self-moving mass of sperm; in some species it stores a motionless spherical mass of sperm. Usually, length of spermatozoa ranges between 70 and 200 μm. Giant spermatozoa (as much as 700 μm long) were found in C. albosignatus.

Key words - Spermatheca, ovipositor gland, testes, male accessory glands, sperm.

In 20 specie di terebranti e 6 specie di tubuliferi sono state esaminate: (a) la variabilità anatomica dei genitali interni maschili e femminili, (b) la forma e la lunghezza degli spermatozoi. Il terebrante Melanthrips fuscus viene utilizzato come specie di confronto.

La spermateca manifesta ampia variabilità interspecifica; nei terebranti, essa manifesta un’ampia gamma di dimensioni, riguardo al diametro del ricettacolo. Un tipo particolare di spermateca spetta al tubulifero Compsothrips albosignatus. La massa degli spermatozoi all’interno del ricettacolo può essere mobile o immobile, secondo la specie.

La ghiandola dell’ovopositore è ovviamente posseduta solo dai terebranti; essa ha dimensioni molto variabili ed esibisce un dotto particolarmente lungo in alcune specie della fam. Thripidae.

Le ghiandole accessorie maschili sono in coppia singola nei terebranti e in doppia coppia nei tubuliferi.

La lunghezza degli spermatozoi ha valori compresi generalmente fra 70 e 200 μm. Spermatozoi giganti, della lunghezza di 700 μm, sono stati trovati nel tubulifero Compsothrips albosignatus.

Parole chiave: Spermateca, ghiandola dell’ovopositore, testicoli, ghiandole accessorie maschili, spermatozoi.