54 Invasive Stink Bugs and Related Species (Pentatomoidea)
2.2.10.2 Aphylinae Bergroth, 1906
This is a small group (two genera, three described and several undescribed species) endemic to Australia
(Tables 2.2, 2.3). As with other pentatomine taxa, it has had an interesting taxonomic history. Originally,
it was described as a subfamily of the Pentatomidae (Bergroth 1906b); that same year, Schouteden pub-
lished a detailed monograph of the subfamily (Schouteden 1906). Reuter (1912) and China and Miller
(1959) treated this group as a family; Gross (1975b) lowered it back to a subfamily, indicating that it might
be related to the podopine genus Tar isa Amyot and Serville. In their review of the World Heteroptera,
Schuh and Slater (1995) once again treated this group as a family, a position which was followed by
Cassis and Gross (2002) and Kment et al. (2012). Recently, as a result of their cladistic analysis, Grazia
et al. (2008) concluded that for now, it should be treated as a pentatomid subfamily. The genitalia of both
sexes, particularly the presence of a distinct pentatomid-type sclerotized rod within the dilation of the
female spermathecal duct, support this placement.
Members of this subfamily are relative small (usually less than 5 mm), oval, with the dorsal surface
strongly convex and the pleural and abdominal areas flattened or concave (Schuh and Slater 1995) (Figure
2 .17A). The scutellum, somewhat enlarged, usually extends to the apex of the abdomen but leaves the con-
nexiva and lateral portions of the coria exposed (Figure 2.27A). The pronotum curves downward and pos-
teriorly forming a large posterolateral lobe on each side, with a large, distinct posterolateral notch, which
in turn leaves three to four sclerites of the mesopleural region exposed (normally covered by the forewings
in other pentatomoids); this region has been given the term exponium by Štys and Davidová-Vilímová
(2001). Its function is to draw the defensive secretion from the metathoracic scent glands upwards to the
outer surface of the body (Kment et al. 2012). The head is relatively short and broad, barely extending
anteriorly beyond the compound eyes. The parameres, at least in the genus Aphylum Bergroth, have two
articulating sections. The female spermathecal duct has a distinct sclerotized rod that is narrowed apically
and hooked; the spermathecal bulb is globose with two finger-like diverticula (McDonald 1970).
This subfamily contains two genera, Aphylum (Figures 2.17A, 2.27A) with two described species dis-
tributed in eastern Australia, and the recently described Neoaphylum Štys and Davidová-Vilímová with
a single species only known from western Australia. The only known biological information is that some
specimens have been collected from under the bark of the River Red Gum, Eucalyptus camaldulensis
(Myrtaceae) (Cassis and Gross 2002). Štys and Davidová-Vilímová (2001) stated that the spiracular
structure in Neoaphylum (with a “stopper”-like structure located in each spiracle) indicated that this spe-
cies might be adapted to live in dry, arid regions.
2.2.10.3 Asopinae Amyot and Serville, 1843
The asopines are considered and recognized as a natural (e.g., monophyletic) taxon, having as a defin-
ing synapomorphy a crassate rostrum (Figures 2.5C-E) (Gapud 1991). An adaptation for predation, the
“beak” consists of barbed stylets strengthened by the thickened rostrum are used to “spear” their prey
and hold it at beaks-length, thus limiting potential injury when the prey, typically larvae of holome-
tabolous insects, thrashes in an effort to escape. Additionally, the bucculae are united behind the oral
groove, not open as in the Pentatominae. United bucculae is likely a plesiomorphic character as it is
found in other pentatomid groups (e.g., Edessinae) as well. In many, but not all, genera, the forelegs seem
to be adapted for predation with spurs on the profemora and a foliate expansion of the protibiae (also
seen in several phytophagous species) (Figure 2.27B), possibly to ward off counter-attacks by the prey.
Barão et al. (2013) cite the protibiae of asopines as unique and a defining apomorphy for the subfamily.
Many asopines have the evaporatoria reduced compared to the typical non-predatory stink-bugs and such
reduction would presumably minimize the problem of the scent giving away their presence to potential prey.
Predatory behavior is not limited to the asopines. Insectivory by species in the halyine genus
Brochymena Amyot and Serville has been observed with sufficient frequency to conclude that they
are at least adventitious predators. They have a non-crassate rostrum and, thus, lack specific adapta-
tions for predation unless one counts the foliate protibiae and reduction in the external structures of the
metathoracic scent gland apparatus. Reductions in the scent gland apparatus occurs in some unrelated
pentatomines and podopines (e.g., Braunus Distant, Murgantia Stål, Tor nosia Bolívar) but is likely a