HESPERINIDAE

Sinclair, Bradley J., Borkent, Art & Wood, D. Monty, 2007, The male genital tract and aedeagal components of the Diptera with a discussion of their phylogenetic significance, Zoological Journal of the Linnean Society 150 (4), pp. 711-742 : 718-720

HESPERINIDAE

Description ( Fig. 3A )

Testis: Each testis of Hesperinus Walker is oval and sack-like, partially collapsed in the material examined.

Epididymis: Not differentiated.

Vas deferens: These ducts are long, slender, and slightly twisted. The ducts extend posteriorly to the base of a large fused accessory gland complex. At their most posterior extension, the vasa deferentia are expanded into kidney-shaped chambers of unknown function (perhaps similar to the inflated sacs in Tipulidae ). From these structures, the ducts join medially and arch anteriorly and are continuous with the apex of the accessory gland complex.

Accessory gland and seminal vesicle: A large accessory gland complex is present with at least two distinct chambers visible. The gland remains divided medially throughout its length. No distinct seminal vesicle is present, although the large kidney-shaped expansions of the vasa deferentia may function as storage chambers.

Ejaculatory duct: At the posterior end of the accessory gland complex, a pair of medially joined ejaculatory ducts exits. They are rather thick walled and extend to the sperm pump.

Ejaculatory apodeme, sperm pump, and aedeagus: The ejaculatory apodeme is T-shaped in Hesperinus , with broad wing-like lateral arms ( Sinclair, 2000: fig. 8). The apodeme extends posteriorly to near the apex of the aedeagus. The aedeagus is mostly sclerotized in Hesperinus , with a narrow apical phallotrema (or secondary gonopore at the apex of the aedeagus) ( Sinclair, 2000: fig. 11).

Remarks: The male genital tract of Hesperinus is here described and illustrated for the first time. The broad lateral plates on the ejaculatory apodeme for the insertion of large muscles appear to be unique among the Bibionomorpha and similar to those observed in some Tipulidae ( Wood, 1991: fig. 3a) and lower Brachycera ( Sinclair, Cumming & Wood, 1994).

Figures

Figure 3. Male internal reproductive organs (dorsal view). A, Hesperinus rohdendorfi (Hesperinidae). B, Plecia membranifera (Bibionidae). C, Bibio flavihalter (Bibionidae), left vas deferens and testis removed (based on the specimen photographed in Fig. 4A). D, Pachyneura fasciata (Pachyneuridae). acc gl cplx, accessory gland complex; ej dt, ejaculatory duct; tes, testis; vas df, vas deferens. Scale bars = 0.1 mm.