Acanthosoma fallax, Tsai & Rédei, 2015

Tsai, Jing-Fu & Rédei, Dávid, 2015, The genus Acanthosoma in Taiwan (Hemiptera: Heteroptera: Acanthosomatidae), Acta Entomologica Musei Nationalis Pragae 55 (2), pp. 625-664 : 634-637

Acanthosoma fallax sp. nov.

( Figs 8–9 , 29–32 , 50–51 , 68–71 )

Acanthosoma forfex (non Dallas, 1851): ISHIHARA (1943: 495). Misidentification (cf. TSAI & RÉDEI 2015b: 31).

Acanthosoma asahinai (non Ishihara, 1943): ZHENG & LIN (2013: 92) (partim). Misidentification.

Type material. HOLOTYPE: J, TAIWAN: NANTOU CO.: Meifeng Farm , faculty dorm, 5.v.2014, at light, leg. J.F.Tsai; mounted on card, left antennal segments III–IV lacking; deposited at NMNS ( Figs 68–69 ) . PARATYPES: TAIWAN: CHIAYI CO.: Jhuchi, Fenchifu , 30–31.x.2003, sweeping, leg. C.S. Lin, NMNS ENT 4288–1069 (1♀ NMNS) . HSINCHU CO.: Guanwu , 16.xi.2011, leg. Y.B. Fan (1 J 1 ♀ TFRI) . TAICHUNG CO.: Da Syue Shan Forstry Rd. 42k, 26.ix.2009, leg. Y.J. Liu (1 J HNHM) ; Wuling Farm, Cika Cabin , 2.x.2010, leg. C.T. Tang (1 J 1 ♀ NCHU) ; Anmashan , 6–9. vii.1979, leg. W.J. Wu (1 J [dissected], NCHU) . NANTOU CO.: Tsuifeng , 1.viii.1985, H. Takizawa leg. (1 J SEHU) ; Yuanfeng , 13.iii–10.iv.2007, Malaise trap, leg. C.S. Lin & W.T. Yang (1 J NMNS) .

Diagnosis. Recognized by the following combination of characters: humeri relatively short, spiniform, directed laterad, apically sharp; hind tibia simple, not dilated (J, ♀); genital capsule of male with a pair of very long, posteriorly directed, weakly diverging lateral projections slightly curved inward and gradually tapering distally, apically with a tuft of setae ( Figs 8–9 ); minute denticles at posterolateral angles of ventrites III–VI black but otherwise lateral margin of pregenital abdomen without conspicuous black markings. The female of this species is similar in size, colour, and in the presence of sharp humeral processes to that of A. asahinai , but the broadly rounded posterior margin of laterotergites VIII ( Figs 50–51 ) sharply differs from the condition found in the latter species ( Figs 48–49 ).

Description. Colour. Dorsum rather uniformly bright green (becomes paler in dead specimens), venter pale yellow; humeral processes yellow to pale orange; abdominal ventrite VII laterally (J, ♀), genital capsule (J) / terminalia (♀) suffused with red; minute denticles at posterolateral angles of ventrites III–VI black but otherwise lateral margin of abdominal segments II–VII (J) / II–VI (♀) pale yellow, posterior portion of connexival plates of segment VII and neighbouring proximal portion of tergite VIII (♀) with black markings ( Fig. 50 ), mesal portions of laterotergites VIII with dark marking surrounding postgenital segments ( Fig. 51 ); antenna as ground colour of body but apical 3/4 of segment IIb and whole of segments III–IV black in male; legs yellowish.

Integument and vestiture. Body glabrous except of fine, scattered hairs on appendages and terminalia; mandibular plates with a few scattered black punctures, interocular area with a pair of irregular longitudinal rows of black punctures; maxillary plate with an obtuse tubercle anteriad and mesad of antennal insertion; pronotum, scutellum and sclerotized parts of fore wings with rather uniform black punctation except on calli, distal portions of humeral processes and costal margin of fore wing, punctation of exocorium and neighbouring part of endocorium not conspicuously different; ventral surface of body virtually unpunctured.

Structure. Body elongate oval with distinctly produced humeri, distance between tips of humeral processes about 1.3–1.35 (J) / 1.4 (♀) times as long as greatest width of body posteriad of humeri. Head 1.1–1.15 (J) / 1.2–1.3 (♀) times as broad as its median length, 1.5–1.6 (J) / 1.5–1.55 (♀) times as broad as interocular distance, finely transversely rugose, anterior portion of clypeus with a broad median longitudinal groove. Labium projecting between or slightly surpassing mid coxae. Pronotum with anterolateral margin weakly concave, gradually transitioning into humeral process which is short, spiniform, directed subhorizontally, apically sharp. Thoracic pleuron and sternum. Mesosternal carina distinctly surpassing base of head, highly elevated, rather broadly rounded anteriorly; metathoracic scent gland ostiole with a long, slightly arched peritreme.

Male and female terminalia. Male. Genital capsule ( Figs 8–9 ) with a pair of elongate and rather gracile, posteriorly directed, curved lateral projections tapering distally, apex of each projections with a tiny denticle and a tuft of hairs; dorsal rim with a small, obtuse concavity medially; ventral rim with a pair of setal tufts laterad of paramere sockets. Paramere ( Figs 25–28 ) T-shaped, dorsal arm with a small subapical denticle directed backward, ventral arm beak-like apically. Female ( Figs 50–51 ). Posterolateral angle of ventrite VII relatively strongly produced, curved, posterior margin with a deep, broadly U-shaped median incision surrounding valvifers VIII; posterior margin of laterotergites VIII truncate; Pendergrast’s organs of ventrites VI and VII elliptical, subequal in size.

Measurements (in mm). Body length from apex of head to apex of membrane 13.7–15.3 (J) / 16.1–16.7 (♀), from apex of head to line connecting apices of projections of genital capsule 17.2–17.8 (J); greatest width of body posteriad of humeral processes 6.40–8.05; median length of head 2.09–2.23, width across eyes 2.40–2.68, interocular distance 1.55–1.80; length of antennal segments (I) 1.60–1.88: (IIa) 1.90–2.00: (IIb) 1.45–1.85: (III) 2.15–2.30: (IV) 1.90–2.00; median length of pronotum 2.68–3.28, greatest width (across tips of humeri) 8.70–11.02; median length of scutellum 4.02–5.36, width at base 3.58–4.77.

Etymology. The specific epithet is the Latin adjective fallax (m, f, n) (‘deceptive, deceitful’) referring to the fact that the species was misidentified by previous authors.

Bionomics. Unknown. It is sometimes attracted to light.

Distribution. The species is apparently endemic to Taiwan, distributed in the Quercu s forest zone of mountains ranging from 1500 to 2500 m in altitude. Its distribution overlaps with that of A. asahinai , but the latter species frequently occurs at lower altitudes.

Remarks. The identity of Acanthosoma forfex Dallas, 1851 was elucidated by TSAI & RÉDEI (2015b). The record of A. forfex from Taiwan ( ISHIHARA 1943) is based on misidentification and pertains to A. fallax sp. nov. The redescription of A. asahinai by ZHENG & LIN (2013) contains a combination of characters of both A. asahinai and A. fallax sp. nov.; the top left photo in their p. 92 shows A. asahinai , the top right one A. fallax sp. nov.

The elongate posterolateral projections of the genital capsule and the shape of the paramere indicate that the new species belongs to the Acanthosoma forfex species group as it was defined under A. asahinai . It is morphologically similar to A. forfex , but it can be distinguished by the apically sharp humeral process (obtuse in A. forfex ), unicolorous abdominal connexiva and ventrites (with conspicuous black markings in A. forfex ), and the long, gracile, curved lateral projections of the genital capsule (much shorter and less gracile in A. forfex ). The character states of A. forfex were illustrated by TSAI & RÉDEI (2015b). The species can readily be distinguished from A. asahinai by the shape of genital capsule of the male, the truncate posterior margin of laterotergites VIII of female, and the simple hind tibiae of male (subbasally dilated in A. asahinai ). The processes of the male genital capsule of A. fallax sp. nov. are distinctly longer than those of all other known congeners.

Figures

Figs 1–10.Acanthosoma spp., males. 1 – A.atayal sp.nov., posterior part of abdomen, ventral view; 2 – same, genital capsule and exposed part of segment VIII, ventral view; 3 – same, genital capsule, lateral view; 4 – A. haemorrhoidale formosanum subsp. nov., holotype, genital capsule, posterior view; 5 – A.haemorrhoidale haemorrhoidale (Linnaeus, 1758) (Spain: Fuente Dé, HNHM), genital capsule, posterior view; 6 – A. asahinai Ishihara, 1943, posterior part of abdomen, ventral view; 7 – same, genital capsule, ventral view; 8 – A. fallax sp. nov., posterior part of abdomen, ventral view; 9 – same, genital capsule, ventral view; 10 – A. pugnax sp. nov., genital capsule and exposed part of segment VIII, ventral view. Scales in mm.

Figs 20–44. Acanthosoma spp., right parameres in different views. 20–21 – A. atayal sp. nov.; 22 – A. haemorrhoidale formosanum subsp. nov., holotype; 23 – A. haemorrhoidale ouchii Ishihara, 1950 (China: Sichuan, Mt. Emei, USNM); 24 – A. haemorrhoidale haemorrhoidale (Linnaeus, 1758) (Spain: Fuente Dé, HNHM); 25–28 – A. asahinai Ishihara, 1943; 29–32 – A. fallax sp. nov.; 33–36 – A. pugnax sp. nov.; 37–39 – A. axicia sp. nov.; 40–41 – A. laevicorne Dallas, 1851; 42–44 – A. expansum Horváth, 1905. Scales in mm.

Figs 45–51. Acanthosoma spp. 45 – A. atayal sp. nov., female terminalia, posteroventral view; 46 – A. haemorrhoidale formosanum subsp. nov., paratype, female terminalia, posteroventral view; 47 – A. asahinai Ishihara, 1943, hind tibia of male; 48 – same, female terminalia, dorsal view; 49 – same, posteroventral view; 50 – A. fallax sp. nov., female terminalia, dorsal view; 51 – same, posteroventral view. PO6, PO7 = Pendergrast’s organs of ventrites VI and VII, respectively. Scales in mm.

Figs 68–71. Acanthosoma fallax sp. nov. 68–69 – male (holotype, right antennal segments III–IV reconstructed digitally); 70–71 – female. Scales in mm.