Hemitrochostoma Bergroth, 1913

Redei, David & Jindra, Zdenek, 2015, A revision of the genus Hemitrochostoma (Hemiptera, Heteroptera, Plataspidae), ZooKeys 495, pp. 63-77 : 64-69

Taxon classification Animalia Hemiptera Plataspidae

Genus Hemitrochostoma Bergroth, 1913

Hemitrochostoma Bergroth, 1913: 176. Type species by monotypy: Hemitrochostoma altilabris Bergroth, 1913.

Inflatilabrum Tomokuni, 2012: 40. Type species by original designation: Inflatilabrum lambirense Tomokuni, 2012. New subjective synonym.

References.

Rédei and Bu 2013: 272 (morphology).

Diagnosis.

Recognized within Plataspidae based on the combination of the following characters: body of medium size (6-7 mm), relatively elongate, about 1.5-1.8 times as long as wide, moderately convex dorsally (Figs 1-4); mandibular plates broadly laminate, produced far anteriad of apex of anteclypeus and broadly overlapping in both sexes (Figs 5-8); labrum highly elevated, crest-like, semicircular in lateral view (Fig. 11).

Redescription.

Body of medium size (total length about 6-7 mm), elongately oval, moderately convex dorsally, nearly flat ventrally (Figs 1-4). Colour, integument and vestiture. Dorsum brown with stramineous areas on head and pronotum; integument dull, smooth, with dense, weak, superficial, rather irregular punctation dorsally, with only insignificant, indistinct punctures ventrally; with scattered, inconspicuous, fine, short, erect setae dorsally and ventrally, antennae and legs with more conspicuous short, semierect pilosity.

Head and cephalic appendages. Head (Figs 5-8) 1.05-1.1 times as long as its width across eyes, about as long as or slightly longer than median length of pronotum, about half as broad across eyes as humeral width of pronotum, width across eyes 1.3-1.35 times (male, female) as broad as interocular distance; sexually dimorphic: males (Figs 5, 7) with more strongly broadened mandibular plates than females (Figs 6, 8); anteclypeus thick, with lateral margins arched, therefore anteclypeus distinctly broader at its middle than apically and basally, dorsally elevated above level of mandibular plates (Fig. 11); mandibular plates broadly, laminately produced, far surpassing apex of clypeus, overlapping medially anteriad of clypeus but separated from apex of clypeus by a distinct gap, lateral margin of mandibular plates sharp, reflexed, distinctly ( Hemitrochostoma altilabris male, Hemitrochostoma rutabulum male, female) or insignificantly ( Hemitrochostoma altilabris female) emarginate anteriad of eye, portion anteriad of apex of clypeus strongly turned upwards; antennal insertion situated closer to mesal margin of eye than to base of labium (Fig. 10); buccula short, restricted to basal half of ventral side of head; labrum subdivided into a broadly inflated proximal portion (Figs 10-11: lbrp) and a highly elevated, crestlike distal portion semicircular in lateral view (Figs 10-11: lbrd); compound eyes very small (male, female), distinctly protruding laterally; ocelli small, interocellar distance about 2 times as long as distance between ocellus and ipsilateral eye. Antenna simple, segment II subdivided into two secondary segments, segment I not reaching apex of head, thickened at its basal half, segment IIb very short, ring-like, segments IIb–IV distinctly flattened. Labium reaching or surpassing posterior margin of abdominal ventrite III; segment I (Figs 10-11: lb1) thick and short, not reaching base of head, diameter of segments II–IV much smaller, segment III distinctly longer than segment I, segments II and IV subequal in length, both distinctly longer than segment I.

Thorax and thoracic appendages. Pronotum (Figs 5-8) more than two times as broad as its median length, moderately declivous anteriorly; anterior collar narrow but distinct; lateral margin broadly, laminately explanate, more or less strongly produced anterolaterad reaching or surpassing anterior margin of eye, gradually narrowed posteriad, more or less emarginated anteriad of humeri in dorsal view; humeral angle rounded, obtuse, distinct; posterior margin broadly rounded, posterolateral angle obsolete. Scutellum wider than long, lateral margins abruptly broadened at their extreme base, then moderately broadening posteriad, forming a broadly rounded angle at two thirds of its length, then more strongly narrowing towards apex; basal tumescence weak, posteriorly delimited by a broad and very shallow transversal furrow; disk with a very indistinct median carina; basolateral angle not delimited by furrow; with a fine submarginal impression along almost entire length except at extreme base; posterior margin shallowly (female) or more deeply (male) excised above terminalia. Thoracic pleura and sterna (Fig. 9). Proepisternum simple, not tumescent; metapleuron with a well developed scent gland ostiole situated about halfway between base of hind coxa and dorsal margin of metapleurite, associated with a distinct, well developed but rather short, highly elevated, elongate, weakly curved peritreme; mesosternum forming a broad, obtuse, rather low median carina, posterior margin V-shaped and distinctly produced between mid coxae; metasternum relatively narrow, elevated and somewhat tumescent, but meso- and metasterna not forming a contiguous carina. Evaporatorium occupying most of thoracic pleuron and sternum except broad lateral explanate margin of propleuron, adjacent broad region of proepisternum, and pro-and mesothoracic supracoxal lobes. Fore wing. Exocorium and adjacent small, triangular basal portion of mesocorium exposed in rest. Legs short, femora thickened, tibiae with distinct, broad, deep dorsal furrow along their whole length.

Pregenital abdomen (Figs 9, 26) distinctly broader than long; connexival segments distinctly separated, intersegmental sutures running to lateral margin of abdomen; posterolateral angles of segments IV and V minutely, obtusely, protruding; dorsal laterotergites present in segments III–VI, rather broad; ventral laterotergites greatly fused with the respective sternites (these ventral plates of composite origin are termed ventrites), lateral portions of ventrites III–VII demarcated by a longitudinal furrow, spiracles III–VII situated close to this furrow mesally and about halfway between anterior and posterior margin of each segment; segments III–VII each with 2 pairs of longitudinally arranged trichobothria situated posteriad and somewhat mesad of the respective spiracles in an oval impression; median lengths of ventrites III–VI subequal, that of ventrite VII somewhat longer (female); posterior margin of ventrite VII of female deeply, subtriangularly emarginate (cf. Figs 26, 28, 32); tergite VIII (Fig. 27: t8) short, narrowly desclerotized along midline.

External male genitalia. Genital capsule (Figs 12-15) relatively small (more narrow than width of head), robust, simple, with dorsal sinus elongate. Paramere (Figs 16-17, 22-23) simple, relatively narrow, S-shaped, gradually tapering towards apex. Phallus described in detail for Hemitrochostoma altilabris .

External female genitalia (Figs 28-31). Valvifers VIII subtriangular; laterotergites IX subhorizontal, mesal margin subtruncate; ectodermal genital tracts described in detail for Hemitrochostoma altilabris .

Postgenital abdomen . Male: proctiger elongate, concealing dorsal sinus of posterior aperture of genital capsule in rest, weekly trilobate apically (Figs 13, 15). Female: segment X transversally subdivided into two secondary segments (Fig. 29: t10-p, t10-d) and each of these secondary segments subdivided into a pair of contralateral sclerites along midline.

Distribution and diversity.

The genus previously contained only the type species occurring in northern Borneo. Another species is described in the present paper from Peninsular Malaysia (Perak).