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

mounting by the female. Nonetheless, females of C. punctulatus
have been observed straddling the male prior to
assuming the opposed position (Nalepa, 1988a).
Because tergal glands are often markedly different
among different genera and species, they can be useful
characters in cockroach taxonomy (Brossut and Roth,
1977; Bohn, 1993). Morphologically they range from very
elaborate cuticular modifications to the complete absence
of visible structures. The glands may take the form
of shallow or deep pockets containing knobs, hairs, or
bristles (Fig. 6.7), fleshy protuberances, cuticular ridges,
groups of agglutinated hairs, tufts or concentrations of
setae, or just a few setae scattered on the tergal surface. In
species with no externally visible specializations, internal
cuticular reservoirs nonetheless may be present (Roth,
1969; Brossut and Roth, 1977). Sometimes secretory cells
are merely distributed in the epithelium beneath the cuticle,
opening to the exterior via individual pores, and the
presence of pheromone-producing cells is inferred from
female mounting and feeding behavior (e.g., Blaberus,
Archimandrita, Byrsotria—Roth, 1969; Wendelken and
Fig. 6.7 Scanning electron micrographs of the tergal gland of
male Phyllodromica delospuertos (Blattellidae), in increasing
detail. Top, tergite 7, middle, tergal gland, bottom, bristles of the
gland. From Bohn (1999), courtesy of Horst Bohn, with permission
from the journal Spixiana.
considered to be the more anterior ones, because they
draw the female forward, bringing her genitalia into
closer alignment with those of the male (Roth, 1969). The
Anaplectinae and Cryptocercidae have tergal modifications
of unknown functional significance because they
occur in unusual locations. In the former the tergal gland
is on the supra-anal plate (Roth, 1969). In C. punctulatus
the gland is located on the anterior part of the eighth tergite,
completely concealed beneath the expanded seventh
tergite (Farine et al., 1989). Because of its relatively inaccessible
position, it is unlikely that it functions to elicit
Fig. 6.8 Male tergite 7 of representative species of Phyllodromica
(Blattellidae: Ectobiinae) showing two sets of tubular
pouches underlying the tergal gland. The anterior pair of tubes
(“t”) are thick and sometimes branched; the posterior pair of
tubules (“tl”) are very thin and unbranched. The “tl” tubules of
Phy. ignabolivari were lost during preparation and are indicated
by dotted lines. From Bohn (1993), courtesy of Horst
Bohn, and with permission from the Journal of Insect Systematics
and Evolution ( Entomologica Scandinavica).
MATING STRATEGIES 97