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

ization success. This may be accomplished in one of three
basic ways: via the manipulation of rival sperm, by the
circumvention of female control of sperm use, or via internal
courtship of the female (Eberhard, 1985; Simmons,
2001).
A number of intromittent structures in male cockroaches
have been called a penis, pseudopenis, phallus, or
pseudophallus. Although these structures may be associated
with the ejaculatory duct or have the appearance of
organs specialized for penetration, sperm is transferred
indirectly in cockroaches, via a spermatophore. Penis-like
organs therefore function in some capacity other than to
convey sperm directly from the testes of the male to the
sperm storage organs of the female. In P. americana the
pseudopenis, a structure of the left phallomere, is characterized
as having a blunt, hammer-like tip and a thin dark
ridge along its length (Bodenstein, 1953). According to
Gupta (1947) the expanded tip of the pseudopenis enters
the female gonopore (entry to the common oviduct) during
copulation, and rotates 90 degrees on its own axis. In
some Blattellidae (including Blattella) a conical membranous
lobe between the right and left phallomeres is considered
a penis. It is a posterior continuation of the ejaculatory
duct and projects into the female genital chamber
during copulation. A free spine, or virga, extends through
the membranous wall of the penis above the gonopore.
Snodgrass (1937) noted that males insert the virga into
the female’s spermathecal groove during copulation, and
suggested that it functioned to guide the sperm of the
copulating male to their storage destination. Because
sperm remain in the spermatophore until after the pair
disengages, however, the functional basis of the virga
must be sought elsewhere. In Pseudophyllodromiinae,
R3, a sclerite of the right phallomere, has an expanded anterior
edge that is elongate, in some genera extraordinarily
so. Most often it is curved and flat, but in Supella it is
Fig. 6.12 Diagrammatic representation of the external genitalia of Blattella germanica during
copulation. (A) Side view of the initial position, female superior. The hooked left phallomere is
extended and inserted into the genital chamber of the female. (B) The insects in the end-to-end
position, ventral view. The paraprocts are holding the ovipositor from each side and the cleft sclerite
is holding it from the ventral side. The last sternite in both insects and the endophallus have
been removed. After Khalifa (1950), with permission from the Royal Entomological Society. Labels
of the various structures courtesy of K.-D. Klass.
MATING STRATEGIES 103