Reproductive biology of the male little mastiff bat, Mormopterus planiceps (Chiroptera: Molossidae), in Southeast Australia

Abstract

The anatomy, biology, and chronology of reproduction in the male of the long penile form of Mormopterus planiceps was studied in southeast South Australia and Victoria. In the morphology of its primary and accessory reproductive organs, M. planiceps was generally reminiscent of other Molossidae; however, in the specialized (sebaceous) nature of the Cowper's gland ducts, in the presence of para-anal glands, and in the unusual, horizontally bifid glans penis and the greatly elongated os penis, it was distinct from other Molossidae studied to date. Young of the year were not reproductively active. Adults displayed a single annual spermatogenic cycle that commenced in spring (September/October) and culminated in spermiogenesis in autumn (February-May), during which period plasma levels of testosterone overtook androstenedione. Thereafter, spermatogenesis appeared to cease (though scattered sperm were seen in the seminiferous tubules until August), but abundant epididymal sperm reserves persisted until September/(October). The accessory glands were hypertrophied during this period, becoming involuted by October. Although the numbers of animals available for study were small, these observations, together with the appearance of spermatozoa in the ductus deferens in August/September suggested that mating could occur during the interval from autumn to spring. Late winter/spring insemination is normal for molossids from temperate environments. However, protracted spermatogenesis commencing in spring that is not accompanied by the availability of spermatozoa until autumn, and a subsequent apparent extension of fertility (epididymal sperm storage, accessory gland hypertrophy) beyond the testicular gametogenic phase, are aspects of the male reproductive cycle in M. planiceps that have not heretofore been described in another molossid bat.

Patterns of Leydig cell and LH gonadotroph activity, and plasma testosterone concentrations in the seasonally reproducing Schreibers' long-fingered bat (Miniopterus schreibersii)

“…Similar changes in size and ultrastructure of the Leydig cells of bats have been described and correlated with changes in reproductive condition and testosterone production (Miller, 1939;Pearson et ai, 1952;Krutzsch, 1975;Kayanja & Mutere, 1978;Gustafson, 1979Gustafson, , 1987Ohata, 1979;Loh & Gemmell, 1980;Bernard, 1986;Krutzsch & Crichton, 1987). In the present study, the increase in size of the Leydig cells and concomitant changes in ultrastructure during spermatogenesis support the occurrence of a period of elevated steroidogenesis at this time.…”

A molecular and morphological investigation of species boundaries and phylogenetic relationships in Australian free-tailed bats Mormopterus (Chiroptera : Molossidae)

“…The phallus is by far the longest in the genus (9-11 mm) and is described in detail in Krutzsch and Crichton (1987). The glans penis averages nearly 9 mm and is highly distinctive in shape (Fig.…”

“…The glans is long and slender and divided into two parts roughly equal in length. Krutzsch and Crichton (1987) describe these two parts as the primary glans (dorsal) and secondary glans (ventral) and these are demarcated by a large lateral opening on the ventral side. The head of the glans (bacular mound) is broad and rounded posteriorly but quickly tapers to a blunt point that is ventrally inflected.…”

Testicular migration, spermatogenesis, temperature regulation and environment of the sheath-tail bat, Taphozous georgianus

“…In the majority of mammals the testes and epididymides migrate to their final position soon after birth, but in some species there is a seasonal testicular migration with the testes and epididymides descending into the scrotum only for the duration of the breeding season. Such seasonal testicular migrations are seen in chiropterans (Krutzsch, 1955;Marshall & Corbet, 1959; Krutzsch & Crichton, 1987), insectivores (Marshall, 1911), rodents (Rasmussen, 1917;Moore et al, 1934), carnivores (Koudele, 1986) and primates (Ramakrishna & Prasad, 1967).…”