Cockroache; Ecology, behavior & history - W.J. Bell

In those cockroaches that apparently possess both
spermathecae and spermathecal glands, ambiguity as to
whether all branches function in sperm storage has implications
for species in the Blaberidae. Based on morphological
observations, most species in this family have
been described as having a pair of spermathecae and a
pair of spermathecal glands, some of them quite elaborate
(McKittrick, 1964). In R. maderae, for example (Fig.
6.17), the glands are large, slender, highly branched, and
open posterior to the openings of the spermathecae (van
Wyk, 1952). Spermathecal glands in Diploptera entwine
each spermatheca, and are “constantly filled with an intensely
basophilic secretion” (Hagan, 1941). Marks and
Lawson (1962), however, reported four paired spermathecae
in Blab. craniifer, with the posterior member of each
pair coiled, slender, and unbranched, and the anterior
member sparsely branched. A functional analysis of these
organs is necessary given their potentially influential role
in sperm handling by the female. Spermathecal glands are
thought to stimulate spermatozoa to enter the spermathecae
(Khalifa, 1950), activate sperm, provide “lubrication”
(van Wyk, 1952), and facilitate the extrusion of the
spermatophore after mating (Engelmann, 1959, 1960).
Spermathecal Shape
Two “basic” spermathecal shapes are represented in cockroaches:
the tubular form, with little difference in width
between the duct and the spermatheca proper ( ampulla),
and the capitate form, shaped like a lollipop. Shape
varies widely across cockroach species and sometimes
within a species. In Agmoblatta thaxteri each spermatheca
has a double terminal bulb, like a figure 8 (Gurney and
Roth, 1966). The genus Tryonicus can be inter- and intraspecifically
polymorphic (Fig. 6.18) (Roth, 1987b);
however, some apparent variation in spermathecal shape
may be due to the amount of ejaculate stored or to the
preservation of specimens at different stages of muscular
activity. Both the ampulla and ducts are surrounded by a
sheath of profusely innervated striated muscle (Gupta
and Smith, 1969). The sheath is best developed at the
base, where it consists mainly of circular fibers and functions
as a sphincter in opening and closing the entry (van
Wyk, 1952).
It has been suggested that spermathecal shape can pre-
Fig. 6.16 Morphological variation in cockroach spermathecae
(A) Arenivaga bolliana; (B) Hypercompsa fieberi; (C) Neoblattella
sp.; (D) Plecoptera sp.; (E) Miriamrothschildia notulatus;
(F) Pseudomops septentrionalis; (G) Parcoblatta virginica; (H)
Blattella germanica; (I) Ectobius pallidus; (J) Loboptera decipiens;
(K) Xestoblatta festae. From McKittrick (1964) and Gurney
and Roth (1966).
Fig. 6.17 Drawing of the anterior view of the female genitalia
of Rhyparobia maderae, showing the tubular spermathecae
(spth, shaded gray) and extensive, branched spermathecal
gland (sp gl). Slightly modified from McKittrick (1964).
MATING STRATEGIES 113