TRICHOCERIDAE

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 : 722

TRICHOCERIDAE

Description ( Figs 2D , 5A )

Testis: Each testis is oval to pyriform, with a thin epithelium continuous with the vasa deferentia.

Epididymis: Not differentiated.

Vas deferens: The vasa deferentia extend posteriorly to the base of the accessory glands, where they arch medially. Each duct abruptly terminates near the anteromedial margin of the accessory gland ( Neumann, 1958; Dahl, 1980).

Accessory gland and seminal vesicle: The accessory glands are paired spherical structures, divided internally into two functionally different chambers ( Neumann, 1958; ‘Samenblase’). The chambers are lined with columnar cells, producing secretions that empty separately into the duct that separates the seminal vesicle and the ejaculatory duct. No spermatozoa have been observed within the chambers of the accessory gland ( Neumann, 1958). The seminal vesicle is interpreted to occur at the apex of each of the vasa deferentia, adjacent to and fused with the accessory glands ( Dahl, 1980). A narrowing of the duct separates the seminal vesicle from the anterior fork of the ejaculatory duct. The seminal vesicle and the accessory gland are enclosed in a continuous sheath of circular muscle ( Neumann, 1958).

Ejaculatory duct: Anteriorly, the ejaculatory duct is paired for a short distance before fusing into a single duct. The circular muscle is very thin and does not function as a pump ( Neumann, 1958).

Ejaculatory apodeme, sperm pump, and aedeagus: There is a small flexible ejaculatory apodeme at the base of a narrow sclerotized aedeagus ( Neumann, 1958; Wood, 1991). The ejaculatory apodeme rotates, compressing the sperm pump and forcing the spermatozoa out through the narrow opening of the phallotrema.

Remarks: The configuration of the male genital tract of the Trichoceridae was thoroughly investigated by Neumann (1958). Our examination of material confirms his interpretation. The male genital duct of Trichoceridae is somewhat similar to Culicidae and Chaoboridae in basic configuration and no preformed spermatophore is produced. Matsuda (1976) assumed that one of the chambers in the accessory gland corresponded to the seminal vesicle in Aedes Meigen. This appears unlikely as spermatozoa are not stored in the accessory gland chambers of Trichocera Meigen.

Figures

Figure 2. Male internal reproductive organs (dorsal view). A, Tipula oleracea L. (Tipulidae) [modified from Keuchenius (1913)]. B, Philorus vividis Kitakami (Blephariceridae) (accessory glands not observed) (scale bar = 0.1 mm). C, Lucilia sp. (Calliphoridae) [modified from Hori (1960)]. D, Trichocera annulata Meigen (Trichoceridae) [modified from Neumann (1958)]. E, Phlebotomus sp. (Psychodidae) [modified from Just (1973) and Perfil’ev (1968)]. F, Sylvicola sp. Anisopodidae [modified from Abul-Nasr (1950) and Dahl (1980)]. acc gl, accessory gland; aed, aedeagus; ej dt, ejaculatory duct; sem ves, seminal vesicle; spm pmp, sperm pump; tes, testis; vas df, vas deferens.

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.