Acanthosoma Curtis 1824
Creators: name: Tsai, Jing-Fu
name: Rédei, Dávid
Publisher: name: Zenodo
Year: 2015
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Hemiptera
Acanthosomatidae
Acanthosoma

description: Key to the species of Acanthosoma occurring in Taiwan   
1 Humeri rounded, slightly surpassing costal margins of fore wing laterally................. 2  
– Humeri produced into distinct processes of various length (Figs 56–91).................... 3  
 2 Body large (17.5–19.5 mm). Posterolateral angle of pronotum provided with a small, triangular process directed posteriad and extending over base of corium. Black markings of connexival plates enclosing intersegmental sutures broad (as wide as or wider than tibia). Genital capsule of male large, robust, with short, broad, apically rounded lateral projections not surpassing apex of membrane, ventrally densely pilose, provided with 1+1 pigmented denticles subapically and 1+1 denticles proximally. Posterior margin of laterotergites VIII of female broadly rounded, ventrites VI and VII each with a pair of large Pendergrast’s organs............................. A. crassicaudum Jakovlev, 1880   
 – Body of medium size (14.5–16.5 mm). Posterolateral angle of pronotum without small triangular process. Black markings of connexival plates enclosing intersegmental sutures narrow (narrower than tibia). Genital capsule of male provided with a pair of long, slender, posteriorly strongly diverging posterolateral projections, apical halves of projections surpass apex of membrane, ventral surface lacking pigmented denticles. Posterior margin of laterotergite VIII of female truncate, ventrites VI and VII each with a pair of small Pendergrast’s organs................................... A. forficula Jakovlev, 1880   
 3 Posterolateral angles of pregenital abdominal ventrites not produced (Fig. 16). Posterolateral angle of pronotum horizontal, subtriangularly produced and broadly obtuse apically (population in Japan and the Asian mainland) or elevated, finger-shaped, with rounded apex (population in Taiwan), in both cases with black punctures nearly to their tip (Figs 86–91). Genital capsule of male without lateral projection, subquadrate in posterior view, ventral rim with 1+1 pigmented denticles laterally (Figs 16–19). Ventrite VII of female with 1+1 small, black, rounded spots laterad of median incision of posterior margin, Pendergrast’s organs on ventrites VI and VII narrowly separated (Fig. 55).................................................................................... A. expansum Horváth, 1905   
– Posterolateral angles of abdominal ventrites II–VI produced into small, sharp denticles (as in Figs 1, 6, 8, 15, 45–46, 48–55)........................................................................... 4  
4 Connexivum uniformly pale........................................................................................ 5  
– Connexival plates with conspicuous black markings anteriorly and posteriorly, enclosing intersegmental sutures.......................................................................................... 10  
5 Head unpunctured or at most with very few punctures which are pale, never contrasting black............................................................................................................................. 6  
– Head with irregularly distributed black punctures on mandibular plates and between eyes.............................................................................................................................. 7  
 6 Body very large (16.5–20.7 mm) (Figs 80–83, 92–93). Genital capsule of male with a pair of robust, apically rather acute posterolateral projections, with 2+2 denticles on dorsal rim due to extension of dorsal wall over ventral infolding, and 1+1 of protuberances on ventral rim laterally (Fig. 15). Paramere as in Figs 40–41. Posterior margin of laterotergites VIII of female truncate, reaching or slightly surpassing posterolateral angles of ventrite VII; Pendergrast’s organs of ventrite VII larger (diameter more than 0.5 mm) (Fig. 54)................................................................ A. laevicorne Dallas, 1851   
 – Body relatively small (13.8–16.5 mm) (Figs 84–85). Genital capsule of male with a pair of short posterolateral projections, dorsal rim broadly U-shaped, apex of paramere bifurcated. Posterior margin of laterotergites VIII of female broadly rounded, far surpassing posterolateral angles of ventrite VII, posterior margin of ventrite VII with a deep, U-shaped incision margined with black; Pendergrast’s organ of ventrite VI small (diameter less than 0.5 mm).............................................. A. sichuanense (Liu, 1980)   
7 Humeral process long, directed distinctly anterolaterad, apically sharp (Figs 60–63, 72–75).......................................................................................................................... 8  
– Humeral process short, directed laterad, apically sharp (Figs 68–71) or obtuse (Figs 56–59).......................................................................................................................... 9  
 8 Humeral process bright red (Figs 60–63). Head punctured, interocular area with a pair of longitudinal rows of black punctures, maxillary plate without tubercle......................................................................................  A. haemorroidale formosanum subsp. nov.    
 – Humeral process black or brownish (Figs 72–75). Head with very few and faint punctures, interocular area without longitudinal rows of black punctures, maxillary plate with a conspicuous, obtuse tubercle anteriad and mesad of antennal insertion........................................................................................................................  A. pugnax sp. nov.    
 9 Maxillary plate without tubercle. Humeral process short and broad, subtriangular, apically obtuse, reddish brown to red with more or less distinct dark suffusion (Figs 56– 59). Genital capsule of male with a pair of short and broad posterolateral projections, dorsal rim broadly U-shaped, greatly covered by membrane (Figs 1–3). Posterior margin of laterotergites VIII of female strongly protruding; Pendergrast’s organ on ventrite VII of female small (Fig. 45)............................................................  A. atayal sp. nov.    
 – Maxillary plate with a conspicuous, obtuse tubercle anteriad and mesad of antennal insertion. Humeral process spiniform, directed laterad, yellow to pale orange (Figs 68– 71). Genital capsule with a pair of elongate, gracile, arched posterolateral projections far surpassing apex of membrane, dorsal rim narrowly U-shaped, concave at midline (Figs 8–9). Posterior margin of tergite VIII of female truncate, not surpassing posterolateral angles of abdominal segment VII; Pendergrast’s organs of ventrites VI and VII of female elliptical, of equal size (Fig. 51)........................................  A. fallax sp. nov.    
 10 Head with irregularly distributed black punctures on mandibular plates and between eyes. Hind tibia of male dilated subbasally (Fig. 47). Genital capsule of male with a pair of long, subparallel posterolateral projections (Figs 6–7). Posterior margin of tergite VIII of female prominent, far surpassing posterolateral angles of segment VII (Fig. 48–49)................................................................................. A. asahinai Ishihara, 1943   
– Head unpunctured or at most with very few punctures which are pale, never contrasting black. Hind tibia of male not dilated.......................................................................... 11  
 11 Humeral process relatively long, directed laterad (population in Taiwan) or more or less anterolaterad (population in Japan and the Asian mainland), frequently red. Male genital capsule with a robust, apically obtusely rounded posterolateral projections not surpassing apex of membrane, widely separated by a broad median incision, ventral rim broadly excavate, of rather rectangular outline, densely pilose, with a pair of small, pigmented denticles. Posterior margin of ventrite VII of female with a pentagonal median incision; Pendergrast’s organs of ventrites VI and VII small (diameter less than 0.5 mm), rather broadly separated.......................................... A. firmatum (Walker, 1868)   
 – Humeral process short, invariably directed laterad, yellow to pale orange, never red (Figs 76–79). Male genital capsule with a pair of scissors-like posterolateral projections surpassing apex of membrane by their apical halves, dorsal rim nearly V-shaped, ventral surface densely covered by long setae (Figs 11–14). Posterior margin of ventrite VII of female with a shield-shaped median incision; Pendergrast’s organs of ventrites VI and VII large (diameter more than 0.5 mm), narrowly separated (Fig. 52)...........................................................................................................................  A. axicia sp. nov.
description: Published as part of Tsai, Jing-Fu & Rédei, Dávid, 2015, The genus Acanthosoma in Taiwan (Hemiptera: Heteroptera: Acanthosomatidae), pp. 625-664 in Acta Entomologica Musei Nationalis Pragae 55 (2) on pages 627-629, DOI: 10.5281/zenodo.5303571