SIPHONAPTERA

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 : 715-716

SIPHONAPTERA

Description ( Fig. 1C )

Testis: Each testis is spindle-shaped, not divided into follicles ( Matsuda, 1976), but comprising bundles of spermatozoa ( Mead-Briggs, 1962).

Epididymis: The outer tissue of the testis is enclosed posteriorly in a coiled tubular epididymis and probably functions as the seminal vesicle ( Mead-Briggs, 1962).

Vas deferens: Each vas deferens leads posteriorly from the epididymis and the two are united at midlength in a common sheath. After uniting, the common duct arches anteriorly and loops around the median accessory glands, to which it is loosely attached (Mead- Briggs, 1962). This duct empties directly into the fused ejaculatory ducts.

Accessory gland and seminal vesicle: Paired accessory glands, sometimes comprising two pairs of lobes of unequal sizes, separately enter the ejaculatory duct prior to the ejaculatory bulb (see Fig. 1C , right). The glands are composed of columnar epithelial cells and have a secretory function ( Günther, 1961; Mead- Briggs, 1962; Matsuda, 1976; Cheetham, 1988: fig. 84). No seminal vesicle has been identified.

Ejaculatory duct: The paired vasa deferentia become continuous with the paired, ejaculatory ducts, which unite at the level of the ejaculatory bulb ( Mead-Briggs, 1962; Cheetham, 1988).

Ejaculatory apodeme, sperm pump, and aedeagus: There are two sperm pumping devices in Siphonaptera ( Günther, 1961; Cheetham, 1988; Hünefeld & Beutel, 2005). The proximal pump is termed the ejaculatory bulb (sometimes the walls bear an ejaculatory sclerite) and is separated from the base of the endophallus ( Günther, 1961: fig. 26; Mead-Briggs, 1962). Distally beyond the gonopore is the second pumping device, a musculated chamber ( Günther, 1961; Cheetham, 1988; Hünefeld & Beutel, 2005). The aedeagus emerges as a narrow tube, bearing a pair of apical hooks or crochets ( Matsuda, 1976). A pair of penis rods lies within the endophallus and at least one can be protracted from the aedeagus to enter the female bursa copulatrix ( Matsuda, 1976).

Remarks: See the remarks under Mecoptera for a discussion of the phylogenetic position of the Siphonaptera . The vasa deferentia are looped anteriorly, as in many lower Diptera and Mecoptera . However, they do not enter the accessory glands anteriorly, but empty directly into the ejaculatory duct.

Hünefeld & Beutel (2005) also did not regard the sperm pump of Siphonaptera as being homologous with that of Mecoptera or Diptera . The proximal pump may include an ejaculatory sclerite, which is withdrawn anteriorly from the base of the endophallus.

Figures

Figure 1. Male internal reproductive organs (dorsal view). A, Panorpa (Mecoptera), left testis removed [modified from Grell (1942)]. B, Nannochorista (Mecoptera), left testis removed, shaded areas mark discoloured regions (scale bar = 0.1 mm). C, Spilopsyllus (Siphonaptera), with ventral surface of accessory gland on right [modified from Mead-Briggs (1962)]. D, Xenos (Strepsiptera) [modified from Carcupino et al. (1995)]. acc gl, accessory gland; acc gl app, accessory gland appendix; ej dt, ejaculatory duct; epid, epididymis; p ej dt, proximal ejaculatory duct; sem ves, seminal vesicle; tes, testis; vas df, vas deferens.