The Oriental flat bug genus Libiocoris Kormilev, 1957 revisited: re-examination, synonymy, and description of a new genus (Heteroptera, Aradidae)

Abstract Re-examination of type specimens of LibiocorisKormilev 1957, L.poecilus from New Guinea and other taxa assigned to this genus, the Chinese Libiocorisheissi Bai, Yang & Cai, 2006 and Libiocorissinensis Bai, Yang & Cai, 2006 proved to be synonyms, thus L.heissi = L.sinensis syn. n. They are, however, different from Libiocoris Kormilev, 1957 to which they were originally assigned and a new genus Paralibiocorisgen. n. is proposed for them. Therefore Paralibiocorisheissi comb. n. = Libiocorisheissi Bai et al., 2006 = Libiocorissinensis Bai et al., 2006, syn. n. From Hainan Island, China, the following new species, P.roundangulussp. n., P.hainanensissp. n., and P.limuensissp. n., are described and figured and a key to species is provided.

Paralibiocoris gen. n. http://zoobank.org/BE3C5C3E-DE96-418B-A434-A60EBC5E0FB8 Type species. Libiocoris heissi Bai, Yang & Cai, 2006. Diagnosis. General aspect similar to Libiocoris Kormilev, 1957 but is distinguished from the type species Libiocoris poecilus (characters in brackets) by the following set of morphological characters: • position of spiracles: II ventral, III-VII lateral and visible from above (II-III ventral IV-V sublateral not visible from above, VI-VII lateral and visible); • fused deltg II+III shorter, reaching only posterior border of metanotum (Figs 1, 3) (extending forward to half-length of mesonotum which is not shown in Fig. 1 of  description but mentioned by Usinger and Matsuda's (1959) redescription, and verified at types (Figs 81,82); • presence of a smooth oblique callus on vltg VII of male which is independent of spiracle VII (Figure 12) (lacking and not developed, fig. 4 of ); • fused median longitudinal sclerite reaching from pronotum to tergal plate bottleshaped along meso-and metanotum, then restricted along mtg I+II and carinate, the fusion line between metanotum -mtg I+II marked by a suture (Figs 5, 7) (narrow and subparallel along meso-metanotum with a longitudinal sulcus, fused to but without a suture between metanotum -mtg I+II) (Figs 81, 82); • median ridge of abdomen distinctly elevated along midline (flat, not developed), dorsally reflexed vltg VII subrectangular (produced posteriorly, long and acute in male, shorter and acute in female); • shape of male pygophore pyriform, produced posteriorly (wide and short).
Paralibiocoris gen. n. is very similar to Bruneiaptera Heiss, 2011 from Borneo, sharing basic habitus and dorsal thoracic structures; however, in Brunneiaptera all spiracles (II-VII) are lateral and visible from above.
Head. Subquadrangular, longer or as wide as distance across eyes; clypeus short, genae slightly produced; antenniferous tubercles short with acute apices; antennae long and slender, first and third and second and fourth segments subequal in length, first stout, incrassate, second and third cylindrical, fourth fusiform; eyes small, granulate; postocular tubercles distinct; rostrum arising from a slit-like atrium, not reaching limits of rostral groove.
Thorax. Pronotum short and wide; anterolateral angles produced forward beyond collar forming large blunt or rounded lobes; disc with a median sulcus; separated from mesonotum by a transverse intersegmental furrow; meso-and metanotum separated only laterally, the elevated median ridge smooth without sulcus; lateral sclerites with longitudinal elevations; metanotum separated from fused mtg I+II by a narrow transverse sulcus; Abdomen. Mtg I and II fused together; mtg III to VI fused into a subquadrangular tergal plate, elevated along midline with usual pattern of large and small callous spots and dots; mtg VII strongly elevated posteriorly in male and slightly elevated in female; pygophore cordate; paratergites VIII clavate or lobiform.
Venter. Prosternum raised and with Y-shaped median carina; meso-and metasternum and sternum II+III fused and flattened medially. Spiracles II ventral, III-VII lateral on dorsally reflexed vltg III-VII and visible from above; spiracle VIII terminal on ptg VIII.
Key to species Paralibiocoris gen. n. from China. As both taxa were described on single females and males are now available, the holotype of heissi is redescribed and additional features of the male added.
Head. Slightly longer than wide across eyes (1.0/0.9); clypeus short reaching basal one-third of first antennal segment, strongly raised anteriorly, with tubercle near apex; genae slightly produced over clypeus; antenniferous tubercles short, dilated, apices acute, diverging anteriorly; antennae 2.1 times as long as width of head across eyes, length of antennal segments I to IV = 0.65, 0.30, 0.65, 0.30; eyes small, not protruding; postocular tubercles small but distinct, not reaching outer margin of eyes; pos- tocular borders behind tubercles straight and converging to constricted collar; vertex with Y-shaped granulate carina flanked by two(1+1) large, ovate infraocular callosities; rostrum short, rostral groove wide and deep, closed posteriorly.
Abdomen. Mtg I and II completely fused, depressed at middle, there with a median longitudinal ridge laterally separated by deep furrows from wide oblique lateral plates, sloping posteriorly and sideways, further laterally with two (1+1) large subtriangular depressions; tergal plate with a slightly raised median ridge on mtg III, a pentagonal elevation on mtg IV then tapering posteriorly.
Male. Morphological features similar to female but of smaller size. Head as long as wide across eyes; median plate of meso-metanotum more elongate 1.82 times as long as wide (0.73/0.40); mtg VII strongly elevated posteriorly; reflexed vltg VII forming triangular lobes posterolaterally, ventral side with a distinct oblique smooth callus, reaching lateral margin; ptg VIII short and clavate much shorter than cordate pyriform pygophore (Figs 13,14); parameres slender .
Distribution. China (Hainan). Comments. As the generic characters and diagnosis are valid for all hereafter described new congeneric taxa, common features are not repeated except those differing in structure of thoracic median plate, size, and measurements distinctive for the specific taxa.  widely rounded (narrow and more produced), shorter antennae 1.79 times as long as width of head (2.1). Paralibiocoris roundangulus sp. n. differs from P. hainanensis sp. n. and P. limuensis sp. n. by a different shape of the median ridge of meso-and metanotum (Figs 22, 24) and shorter antennae which are 1.79 times as long as width of head (1.89 and 1.82 respectively).

Paralibiocoris roundangulus
Description. Male. Basic morphological structures as of P. heissi. Head. As long as wide across eyes (0.82/0.82); antennae 1.79 times as long as width of head across eyes, length of antennal segments I to IV = 0.48, 0.24, 0.44, 0.31.
Etymology. The name of species refers to the widely rounded anterolateral angles of pronotum.

Diagnosis.
General aspect similar to Paralibiocoris heissi, but distinguished from the latter by the wider pronotum, 2.91 times as wide as long (2.80 in P. heissi) and more rounded less produced anterolateral lobes (produced and blunt), shorter anten-  nae 1.89 times as long as width of head (2.1) and by posterolateral angles of deltg V to VII slightly protruding and rounded in female. Paralibiocoris hainanensis sp. n. differs from P. roundangulus sp. n. and P. limuensis sp. n. by a different shape of the median ridge of meso-and metanotum (Figs 43,45 vs. Figs 22,24 and Figs 64,66,respectively) and antennal segment I as long as III (III shorter than I).
Description. Male. Basic morphological structures as of P. heissi and other congeners. Head. Slightly longer than wide across eyes (0.8/0.78); antennae 1.89 times as long as width of head across eyes, length of antennal segments I to IV = 0.47, 0.24, 0.47, 0.30.
Abdomen. Mtg I and II completely fused, disc depressed at middle with a flat rectangular sclerite separated from lateral ovate plates by deep furrows; tergal plate with a slightly elevated granulate ridge which is widest on mtg III, sloping posteriorly; pygophore elongate cordate, surface rugose (Figs 55, 56); parameres slender (Figs 57-59).
Venter. Vltg VII with a small shiny callus, near spiracle VII; spiracles II ventral, III-VIII lateral and visible from above.
Measurements Diagnosis. General aspect similar to Paralibiocoris heissi, but distinguished from the latter by wider pronotum 3.06 times as wide as long (2.80) and more rounded less produced anterolateral lobes (produced and blunt), shorter antennae 1.82 times as long as width of head (2.1) and by antennal segment I longer than III (of same lengths in heissi). Paralibiocoris limuensis sp. n. differs from P. roundangulus sp. n. and P.hainanensis sp. n. by a wider pronotum (3.06 vs. 2.86 and 2.91 respectively) and a leaf-like shape of the median ridge of meso-and metanotum (Figs 60, 62) and smaller size.
Description. Male. Basic morphological structures as of P. heissi and other congeners. Head. Slightly longer than wide across eyes (0.75/0.68); antennae 1.82 times as long as width of head across eyes, length of antennal segments I to IV = 0.40, 0.20, 0.37, 0.27. Pronotum. 3.06 times as wide as long (1.13/0.37); collar narrow; anterolateral lobes produced forward beyond collar as two (1+1) widely rounded granulate lobes, lateral margins converging anteriorly; structure of disc as in other congeners.
Abdomen. Mtg I and II completely fused, disc medially with a barrel-shaped sclerite resembling the leaf-stalk of the leaf -shaped ridge, separated from lateral ovate plates by deep furrows; tergal plate with a slightly elevated granulate ridge which is widest on mtg III, sloping posteriorly; pygophore elongate cordate, surface rugose (Figs 76, 77); parameres slender (Figs 78-80).
Venter. Vltg VII with a glabrous callus near spiracle VII; spiracles II ventral, spiracles III-VIII lateral and visible from above.

The case of Libiocoris indicus Heiss, 1982
The species was described upon two males and a female from Meghalaya State in the north of India, and shares several morphological characters with Libiocoris (habitus, head and antennae, fusion of thoracic segments) and according to the (misleading) redescription of Libiocoris (based on their new species L. antennatus Usinger & Matsuda, 1959) also the position of spiracles II-VII placed laterally and visible from above. Due to this similarity it was "tentatively" assigned to Libiocoris. Re-examination of the paratype male of indicus has shown that it belongs neither to Libiocoris sensu Kormilev, 1957 (abbreviated L below) nor to Paralibiocoris gen. n. (abbreviated P below) showing following set of characters: • position of spiracles: II-VII lateral and visible from above (not L, not P); • fused deltg I+II shorter, reaching laterally only to metanotum (as P, not L); • distinct glabrous oblique callus on vltg VII of male is lacking (as L, not P); • fused median thoracic ridge of different shape (not L, not P); • median thoracic ridge is elevated to sulcus of border metanotum, mtg I+II then sloping posteriorly (as P, not L); • median ridge of abdomen raised along midline (as P, not L); • dorsally reflexed vltg VII is subrectangular and not produced (as P, not L); • shape of pygophore pyriform and produced posteriorly (as P, not L).
The position of spiracles, different from both Libiocoris and Paralibiocoris, is recognized as a diagnostic character used in Aradidae taxonomy for distinguishing genera [e.g., Acaricoris from Kolpodaptera; Parapictinus from Mezira (Usinger & Matsuda, 1959)] which supports a separate generic category for indicus. As other similar specimens from Vietnam and Japan present in our collections need to be included in a separate study, we refrain here from describing a new genus, but this species should be removed from Libiocoris sensu . Inconsistencies and remarkable differences in the descriptions and illustrations of angulatus, antennatus, lobatus, and pilosus compared with poecilus raise questions about their generic assignment.