Taxonomy of the genus Amphiareus (Heteroptera: Anthocoridae) in Southeast Asia

Four species of the genus Amphiareus are recognized in southeastern Asia, including two new species, A. edentulus and A. rompinus, both from Johor, Malaysia. The two known species, A. constrictus (Stål) and A. ruficollaris Yamada & Hirowatari are also diagnosed and figured; the latter is recorded from this region for the first time. The genus is diagnosed and briefly discussed.


INTRODUCTION
The flower bug genus Amphiareus Distant of the tribe Dufouriellini is represented by one cosmopolitan and four Palearctic species (Yamada & Hirowatari, 2003).Among the latter, A. obscuriceps (Poppius, 1909) was recently recorded from North America (Henry et al., 2008).The cosmopolitan species, A. constrictus (Stål, 1860), is distributed mainly in the Old and New World tropics and subtropics.In turn, Palearctic species are inhabitants of temperate to cold temperate areas, except for a single subtropical species, A. ochraceus Yamada & Hirowatari, 2003, that is restricted to the Ryukyus, Japan.Though Amphiareus is widely distributed in the world, its fauna in the tropical region, such as southeastern Asia, has been lightly studied.Only A. constrictus was known to occur in this region to date (Distant, 1910;Péricart, 1996).Three species of this genus have been recognized through the recent continuing investigations of the author and colleagues.
In this paper, Amphiareus of southeastern Asia is revised.Two new species, A. edentulus and A. rompinus, are described below, and the two previously known species are diagnosed based on the specimens from southeastern Asia.The genus is diagnosed, supplementary illustrations included and briefly discussed for distinguishing characters.

MATERIAL AND METHODS
Most specimens were preserved in 80% ethyl alcohol, then dried and mounted for study.Other specimens examined are housed in several other institutions.Examination and illustration of the genitalia and other detailed external structures, such as the metathoracic scent gland, were made from specimens macerated in 5% hot KOH solution for 3-5 min.They were dissected with micro-pins in glycerin on a well-glass slide under a Nikon Stereoscopic Zoom Microscope SMZ1500 binocular microscope.Illustrations were made with this microscope, and with the aid of an eyepiece grid.Photographs presented in this paper were taken using a Hirox digital microscope KH-7700.All measurements are given in millimeters.
Diagnosis.Easily distinguished from other genera of the tribe Dufouriellini by the following characters: oblong ovate body principally yellowish to brownish colored; head produced anteriorly, about as long as width across eyes; rostrum nearly reaching middle of mesosternum; pronotum narrowed anteriorly, with distinct collar and swollen callus; apical portion of corium about as wide as embolium; membrane usually with three veins; ostiolar peritreme almost straight, connected to angulate carina and extending to anterior margin of metapleura; metasternum with bifurcate projection at middle of posterior margin; scissures on abdominal tergite reaching posterior margin of segment II.Yamada & Hirowatari (2003) provided further diagnostic characters.
Remarks.Morphological characters for accurately distinguishing the species in Amphiareus as are stated below: (1) color; (2) length of antennal segment II to head width across eyes ratio; (3) shape of pronotum; (4) length and density of setae on head, pronotum and hemelytra; (5) shape of ostiolar peritreme; (6) shape of pygophore and paramere.
Further, the number and position of teeth on the male fore tibia may be useful in distinguishing the species.Geographical variation may occur in the number of teeth on male fore tibia.The male genitalia is indispensable for reliable identification of the species, as the female lacks useful genital organs such as copulatory tube and omphalus for species separation.
In the key to Japanese species of Amphiareus presented by Yamada & Hirowatari (2003: 291), the present new species, A. edentulus sp.n. and A. rompinus sp.n., will key to couplets 2 and 3 respectively, with A. ochraceus as well as A. ruficollaris and A. obscuriceps.Therefore, the key (2nd and 3rd couplets) is revised as follows: Biology.The species of this genus in southeastern Asia seem to inhabit principally dead plant materials, and are found in various types of dead leaf clusters of the upper part of evergreen trees, on the ground, dead drooping banana leaves, and sometimes dead ferns, where they were collected along with tiny arthropods.These microenvironments in southeastern Asia are characterized by high temperatures and humidity, providing preferable environments, and a variety of prey for Amphiareus and other anthocorid bugs (cf.Mockford, 1993;Lattin, 1999;Henry et al., 2008).The occurrence of Amphiareus species in such habitats was more common than the other genera of Dufouriellini (e.g.Buchananiella, Cardiastethus, Physopleurella).

Diagnosis.
Recognized by the body (Figs 1, 2) that is generally shining yellowish brown, sparsely covered with silky, long, reclining setae, the antennal segment II about 1.2 times as long as head width across eyes, the ostiolar peritreme evenly straight laterad, blunt apically, the male fore tibia (Fig. 17) curved outwards at middle, bearing 15-17 teeth on midventral surface, and the paramere long, weakly curved, gradually tapered toward apex in dorsal view.Remarks.The specimens from southeastern Asia are divisible into two color patterns: (1) head, pronotum, scutellum uniformly yellowish brown, rostrum uniformly pale yellow, hemelytra yellowish brown with apical part of corium and inner half of cuneus widely dark brown, venter of thorax uniformly yellowish brown (Figs 1, 6); (2) head yellowish brown, vertex dark brown, rostral segment II with dark brown tinge, pronotum yellowish brown with posterior half or posterior angles dark brown, scutellum dark brown, hemelytra yellowish brown to brown with apical part of corium and whole of cuneus widely dark brown, posterior half of prosternum and whole of mesosternum dark brown (Figs 2, 7).The specimens of these two types were frequently collected simultaneously and at similar frequences from many localities and various habitats.
Among specimens with coloration type (1) there are sometimes a few specimens that superficially resemble A. morimotoi (Hiura, 1958).They may differ from A. morimotoi by the eye not sexually dimorphic (in A. morimotoi, larger in males than in females), the antennal segment II about 1.2 times as long as head width across eyes (vs.as long as head width across eyes), and ostiolar peritreme evenly straight and blunt at apex (vs.rounded posterior margin and apically connecting to carina).
Structure.Head (Figs 3,8,11) shiny, smooth, sparsely covered with yellow, long, erect setae intermixed with suberect setae; head excluding neck 0.88 times as long as width across eyes; ante-ocular region 0.88 times as long as length of eye in dorsal view; vertex about 1.3 times as wide as eye in dorsal view; postocular region slightly constricted; neck distinct; eye moderately large, prominent, exceeding level of ventral surface of head in lateral view, sparsely covered with very short setae.Antennal segment I (Figs 3,8,11) just reaching apex of head, with short setae around apex; segment II (Figs 3, 8, 11) about 1.1 times as long as head width across eyes, slightly thickened toward apex, sparsely covered with erect setae intermixed with suberect setae, each seta slightly longer than width of segment; segments III and IV (Figs 3,11) subequal in length, 0.73 times as long as segment II, covered with long erect setae intermixed with short reclining setae; longest seta much longer than twice width of segment; segment IV (Figs 3,11) weakly flattened.Rostrum sparsely clothed with silky, short setae; segment III about 1.8 times as long as segment IV; segment IV about twice as long as segment II.
Pronotum (Figs 3,8,11) shiny, smooth, with long, stout, erect setae at one-third of lateral margin and posterolateral corner, sparsely covered with yellow, short, reclining setae; collar with a row of short setae; anterior margin slightly curved inwardly, 0.77-0.79times as long as mesal length; lateral margin sinuate, distinctly carinate on anterior half; posterior margin deeply curved inwardly, about 2.3 times as wide as anterior margin; callus scattered setae, with stout, erect setae and shallow depression near anterior angle, demarcated posteriorly by transverse, sinuate impression with furrows.Scutellum (Fig. 3) sparsely covered with yellow, long, reclining setae, without two foveae at middle.Hemelytra (Figs 3,12) sparsely covered with yellow, long, reclining setae; costal margin slightly constricted basally; most setal bases on clavus distinctly raised trilobed; embolial margin longer than twice length of cuneal margin; membrane with one distinct outermost vein and two invisible inner veins, out-ermost vein bifurcated basally, inner veins remote from outermost vein.Ostiolar peritreme (Fig. 13) evenly straight laterad, most similar to that of A. constrictus; carina touching lateral margin of metapleura.Legs slender, densely covered with yellow, long, suberect setae; male fore tibia (Fig. 18) straight, lacking row of teeth on ventral surface; each tibia bearing several slender spines.
Abdomen densely covered with yellow, short, reclining setae.Pygophore (Fig. 21) strongly asymmetrical in dorsal view, posteroventrally covered with two long, stout setae intermixed with short and medium length setae; paramere (Figs 21-23) very long, nearly straight, curved along left margin of pygophore, approaching the anterior margin of the pygophore; groove running along paramere broad, entirely visible from left posterolateral aspect.
Etymology.From Latin edentulus (= no teeth, toothless), referring to the male fore tibia lacking a row of teeth on ventral surface; an adjective.

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Figs 17-20.Male fore tibia and tarsus.17 Remarks.Amphiareus edentulus sp.n. is closely related to A. constrictus in general habitus and the shape of ostiolar peritreme; it can be distinguished by the straight fore tibia of the male and the lack of a row of teeth on ventral surface (in A. constrictus, curved outwards at middle, with 15-17 teeth on midventral surface), the apex of paramere approaching the anterior margin of the pygophore (vs.much remote from anterior margin).The coloration of pronotum of the new species is also similar to that of A. obscuriceps.However, it is separated from A. obscuriceps by the base of fore tibia tinged with dark brown (in A. obscuriceps, uniformly pale yellow), hemelytra yellowish brown with clavus, apical part of corium, and cuneus widely dark brown (vs.mostly light brown to brown), and the paramere very long, nearly straight, curved along left margin of pygophore (vs.moderately curved, not along left margin of pygophore).
Description.Coloration.Body (Fig. 4) generally reddish brown.Head and pronotum (Figs 4, 9) uniformly reddish brown; margin of the ocelli red.Antennae and rostrum pale yellow; antennal segments III and IV tinged with dark brown; rostral segment II dark brown.Scutellum (Fig. 4) more reddish than pronotum.Hemelytra (Fig. 4) largely reddish brown; clavus and apical part of corium tinged with dark brown; membrane smoky dark ochre, basally blackish.Legs pale yellow; fore tibia basally tinged with dark brown.Venter of thorax brown to reddish brown.Ostiolar peritreme and evaporative area slightly reddish.
Structure.Head (Figs 4, 9, 14) shiny, covered with short, yellow, reclining setae intermixed with long erect setae, densely punctured on dorsal surface; head excluding neck 0.86 times as long as width across eyes; ante-ocular region 0.88 times as long as length of eye in dorsal view; vertex about 1.5 times as wide as eye in dorsal view; postocular region slightly constricted; neck distinct; eye moderately large, prominent, slightly exceeding level of ventral surface of head in lateral view, covered with very short setae.Antennal segment I (Figs 4, 9, 14) just reaching apex of head, with short setae around apex; segment II (Figs 4, 9, 14) about 0.9 times as long as head width across eyes, slightly thickened toward apex, sparsely covered with erect setae intermixed with suberect setae, each seta slightly longer than width of segment; segments III and IV (Figs 4,14) subequal in length, about 0.8 times as long as segment II, covered with long, erect setae intermixed with short, reclining setae; longest setae much longer than twice width of segment; segment IV (Figs 4,14) weakly flattened.Rostrum sparsely furnished with silky, short setae; segment III longer than 1.6 times length of segment IV; segment IV about twice as long as segment II.
Remarks.Amphiareus rompinus sp.n. is most similar in general appearance to A. ochraceus and A. obscuriceps, but is distinguished from both species by the ostiolar peritreme slightly bent posteriorly (in A. ochraceus and A. obscuriceps it is nearly straight and not bent posteriorly); differing from A. ochraceus by antennal segment II about 0.9 times as long as width of head across eyes (in A. ochraceus, about 1.2 times), the callus demarcated posteriorly by transverse, wide, sinuate depression with dense punctures (vs.demarcated posteriorly by dense punctures and rugula, without depression), and nearly symmetrical pygophore (vs.asymmetrical); differing from A. obscuriceps by the uniformly reddish brown head and pronotum (in A. obscuriceps, brown to dark brown) and the groove running along paramere entirely visible from dorsal aspect (vs.visible from left posterolateral view).(Figs 5,10,20) Amphiareus ruficollaris Yamada & Hirowatari, 2003: 298.Holotype: %, Nara, Japan; Osaka Prefecture University.

Amphiareus ruficollaris Yamada & Hirowatari
Diagnosis.Recognized by the blackish brown body (Fig. 5) covered with short dense reclining setae, red to reddish brown postocular region, collar, and callus (Figs 5, 10); antennal segment II as long as head width across eyes, the ante-ocular region about 0.8 times as long as length of eye in dorsal view, and male fore tibia (Fig. 20) nearly straight, bearing 14 teeth on posteroventral surface.
Distribution.Vietnam*, Laos*, Thailand*, Malaysia*; Japan.This species is recorded from southeastern Asia for the first time.
Remarks.This species is allied to A. obscuriceps, from which it is distinguished by the antennal segment II as long as the head width across eyes (in A. obscuriceps, slightly longer than head width across eyes), the red to reddish brown postocular region, collar and callus (vs.uniformly brown to dark brown), the pronotal posterior margin about 2.6 times as wide as anterior margin (vs.2.4 times as wide as anterior margin), and the male fore tibia bearing 14 teeth (vs.18-22 teeth).