CHIRONOMIDAE

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 : 729

CHIRONOMIDAE

Description ( Figs 5F , 7D )

Testis: Each testis is a narrow, spindle-shaped gland ( Abul-Nasr, 1950).

Epididymis: Not differentiated.

Vas deferens: The vasa deferentia are thread-like at the base of the testes, but expand when they abruptly turn and become juxtaposed. They lie to one side and do not lie on the dorsal surface of the accessory gland complex. The ducts are particularly enlarged near the anterior end, packed with spermatozoa. The ducts terminate at the anterior end of the accessory gland complex. The walls of the ducts are thin, often with an outer layer of fat cells ( Wensler & Rempel, 1962: fig. 21).

Accessory gland and seminal vesicle: The accessory gland complex is fused into a slender, paired threechambered complex ( Wensler & Rempel, 1962: fig. 14; Abul-Nasr, 1950: fig. 9). Each section or chamber is separated by a plug ( Wensler & Rempel, 1962). The anterior and posterior sections are short with large oval vacuoles in the epithelium, whereas the middle section is more than twice the length of either of the other chambers, with hexagonal epithelial vacuoles. The divisions of this glandular complex are readily differentiated in whole mounts. The first and third sections are pale compared with the dark middle chamber. The specific function of each section remains unknown in this family.

Ejaculatory duct: A small valve separates the accessory gland complex from the ejaculatory ducts. The paired ducts are bound by circular muscle and remain paired and enter the base of the aedeagus separately ( Abul-Nasr, 1950). This duct is nonglandular throughout.

Ejaculatory apodeme, sperm pump, and aedeagus: As in all other Chironomoidea , the ejaculatory apodeme is absent and the aedeagus is membranous. The homology of the ventral plate remains unconfirmed in Chironomidae . Wood & Borkent (1982) considered the ventral sclerites fused between the gonocoxites of the genus Buchonomyia Fittkau as probable homologues, resembling the condition in thaumaleids. Dorsomedial lobes in several other genera are positioned where a ventral plate occurs in other Chironomoidea .

Remarks: The production of spermatophores has been verified in the Chironomidae , each characterized by two internal cavities ( Nielsen, 1959).

Figures

Figure 5. Male internal reproductive organs (dorsal view). A, Trichocera sp. (Trichoceridae). B, Dixa yamatoma (Dixidae). C, Dixa yamatoma (Dixidae). D, Austrothaumalea zentae (Thaumaleidae). E, Austrosimulium furiosum group (Simuliidae). F, Chironomus plumosus (Chironomidae). acc gl cplx, accessory gland complex; ej dt, ejaculatory duct; tes, testis; vas df, vas deferens. Scale bars = 0.1 mm.

Figure 7. Male internal reproductive organs (dorsal view). A, Androprosopa japonica (Thaumaleidae). B, Austrothaumalea zentae (Thaumaleidae) (based on the specimen photographed in Fig. 5D). C, Culicoides nubeculosus (Meigen) (Ceratopogonidae) [modified from Pomerantzev (1932)]. D, Chironomus plumosus (L.) (Chironomidae) [modified from Wensler & Rempel (1962)]. E, Austrosimulium furiosum species group (Simuliidae) (based on the specimen photographed in Fig. 5E). acc gl cplx, accessory gland complex; ej dt, ejaculatory duct; tes, testis; vas df, vas deferens. Scale bars = 0.1 mm.