CULICIDAE

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 : 731-732

CULICIDAE

Description ( Fig. 6C )

Testis: Each testis is pyriform in shape, often partially clothed in a thick pigmented fat body. The testis is divided internally into a number of clearly defined zones ( Hodapp & Jones, 1961).

Epididymis: Not differentiated.

Vas deferens: The ducts are initially thin walled, but distally a circular muscle sheath occurs ( Hodapp & Jones, 1961). At the level of the accessory glands, the ducts of the vasa deferentia are enlarged and the seminal vesicle is differentiated ( Jobling & Lewis, 1987).

Accessory gland and seminal vesicle: The accessory gland and seminal vesicle are separate glands. The seminal vesicles are either completely separated from each other or are fused through part or all of their length ( Hodapp & Jones, 1961; Lum, 1961a; Jobling & Lewis, 1987). The chambers are united just prior to the entrance to the ejaculatory duct. The accessory glands are either spherical or pyriform glands separated throughout their lengths. The contents of both seminal vesicles and accessory glands empty separately into the ejaculatory duct ( Hodapp & Jones, 1961). The accessory gland of Aedes aegypti (L.) is separated into an anterior and posterior zone on the basis of different secretory cells ( Chen, 1984).

Ejaculatory duct: The ejaculatory duct is generally short, sheathed in circular muscle.

Ejaculatory apodeme, sperm pump, and aedeagus: The true aedeagus is membranous in Culicidae (see ‘Remarks’). The ventral plate (= claspettes) is a complex structure in this family, with detailed arrangements of bristles and processes ( Wood, 1991). The ejaculatory apodeme and sperm pump are absent in Culicidae .

Remarks: As suggested by Belkin (1968), the ‘aedeagus’ of Culicidae is probably a secondary subdivision of the paramere (phallus sensu Belkin, 1968), and hence a sclerotized true aedeagus is considered absent in all Culicomorpha ( Sinclair, 2000) . Consequently, the structures in red in Wood (1991: figs 11, 12 and 14, but not 15) represent articulated lobes of parameral origin. Nevertheless, this sclerite is trough-like and restricts the opening of the phallotrema.

The shape of accessory glands is variable among and within genera of the Culicidae ( Hodapp & Jones, 1961; Lum, 1961a), ranging from spherical to tubular or pyriform. Secretions of the male accessory glands in some Aedes mosquitoes stimulate oviposition and induce monogamy ( Chen, 1984).

Remarks – features of Culicoidea: Among the four families recognized in the Culicoidea, the shape and details of the male genital tract are very similar in both the Culicidae ( Christophers, 1960; Hodapp & Jones, 1961; Lum, 1961a; Jobling & Lewis, 1987) and the Corethrellidae ( McKeever, 1985) .

A mating plug is produced in some Culicidae ( Lum, 1961b; Giglioli & Mason, 1966), secreted from the accessory glands following seminal emission. It has been considered a vestige of the spermatophore rather than a specialized structure ( Giglioli & Mason, 1966; Gerber, 1970). Wood (1978) did not consider the mating plug in Culicidae as homologous to the spermatophore of the Chironomoidea because it is deposited following deposition of the spermatozoa.

Figures

Figure 6. Male internal reproductive organs (dorsal view). A, Dixa yamatoma (Dixidae) (based on the specimen photographed in Fig. 5B). B, Corethrella sp. (Corethrellidae) [modified from McKeever (1985)]. C, Anopheles quadrimaculatus (Culicidae) [modified from Hodapp & Jones (1961)]. D, Ptychoptera nr japonica (Ptychopteridae) (scale bar = 0.1 mm). E, Ptychoptera lacustris (Ptychopteridae) [modified from Just (1973)]. acc gl, accessory gland; acc gl cplx, accessory gland complex; ej dt, ejaculatory duct; sem ves, seminal vesicle; tes, testis; vas df, vas deferens.