Acanthosoma haemorrhoidale formosanum, 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 : 631-632

Acanthosoma haemorrhoidale formosanum subsp. nov.

( Figs 4 , 22 , 46 , 60–63 ) Type material. HOLOTYPE: J, TAIWAN: TAICHUNG CO.: Dasyueshan logging Rd. 37.5K, 5.vi.2011, leg. W.M. Hunting ; deposited in NCHU ( Figs 60–61 ). PARATYPE: TAIWAN: NANTOU CO.: Habonsan , 29.vii.1983, leg. K. Ra (1 ♀ SEHU > NMNS) ( Figs 62–63 ) .

Diagnosis. Differs from the nominotypical subspecies A. haemorrhoidale haemorrhoidale as well as from A. h. angulatum and A. h. ouchii in the greatly elongate, anterolaterally directed, and apically sharp humeral processes ( Figs 60–63 ). The nominotypical species and A. h. angulatum have short, apically obtuse and recurved humeri. Acanthosoma h. ouchii has elongate and anterolaterally directed, but apically broadly rounded and obtuse humeral processes. Morphology of the exoskeleton and genitalia of both sexes ( Figs 5 , 22 , 46 ) as in the other subspecies.

Etymology. The subspecific epithet formosanus of this endemic Taiwanese subspecies is derived from Formosa, the historic name of Taiwan (of Portuguese origin), to which the Latin adjectival suffix - anus (- ana, - anum) was added, therefore to be treated as a latinized adjective.

Distribution. The subspecies is restricted to Taiwan, thus representing the southernmost population of the species. The two specimens known so far were collected in mountainous regions of medium altitude (around 2000 m a.s.l.).

Remarks. The humeral process of the pronotum of A. haemorroidale shows strong intraspecific variability. The following subspecies are currently recognized:

Acanthosoma haemorrhoidale haemorrhoidale: Humeri weakly produced. Distribution: Europe!, the Caucasus ( Azerbaijan, Armenia, Georgia), Iran ( KERZHNER 1964, GÖLLNER- SCHEI- DING 2006). According to KERZHNER (1964) it occurs sporadically in West and East Siberia, the Russian Far East, and Korea, but all records from the Asian parts of Russia were considered as pertaining to A. h. angulatum by VINOKUROV et al. (2010). Records from China are erroneous, probably most of them pertain to A. emeiense Liu, 1980 ( TSAI & RÉDEI 2015b).

Acanthosoma haemorrhoidale angulatum Jakovlev, 1880 : Humeri more strongly produced horizontally, apically slightly recurved, reddish to black. Distribution: East and West Siberia, Russian Far East ( VINOKUROV et al. 2010), Japan!, northeastern China!, Korea (GÖLLNER- SCHEIDING 2006).

Acanthosoma haemorrhoidale ouchii Ishihara, 1950 : Humeri produced into a pair of strongly elongate, anterolaterally directed process with apex broadly rounded, distal part of its anterior margin strongly recurved; humeral process bright red. Distribution: China: Zhejiang (Mt. Tianmu!), Sichuan ( Mt. Emei !) .

Acanthosoma haemorrhoidale formosanum subsp. nov.: Humeri produced into a pair of strongly elongate, anterolaterally directed, apically sharp, bright red processes. Distribution: Taiwan!

Acanthosoma haemorrhoidale is apparently rare in China, and its few available literature records are partially wrong ( TSAI & RÉDEI 2015b). We only could examine a very small number of specimens and it is therefore difficult to decide whether the local forms can be recognized as subspecies, or rather a distinct clinal variation on a latitudinal gradient is present. The difference between the nominotypical subspecies and A. h. angulatum is rather small, it is not always easy to assign a given specimen to any of the two taxa. Both of these forms are distributed over a vast area, and their distribution areas are broadly contiguous. Specimens with long humeri, resembling A. h. angulatum, are present in the southern border of the area of A. h. haemorrhoidale (Crimea, Caucasus) ; the humeri also exhibit geographic variability within the range of A. h. angulatum, e.g. specimens from the Russian Far East have particularly long humeral processes ( KERZHNER 1964). In contrast, A. h. ouchii is separated from the other two above mentioned subspecies by a striking morphological gap. This form is apparently restricted to southern China, and so far it is known only from two localities (Mt. Tianmu in Zhejiang and Mt. Emei in Sichuan) situated far from each other. The new Taiwanese subspecies A. h. formosanus is also distinct morphologically, and its area is separated from those of the populations on the Asian mainland by the Taiwan Strait.

As there are only minor differences in the genitalia of these local populations, we consider them conspecific. The status of the described taxa needs a careful study based on a material more extensive than the one currently accessible to us. Considering their morphological distinctness and geographic isolation it is unlikely that A. h. ouchii and A. h. formosanum are parts of a continuous morphocline, and therefore they convincingly merit subspecies rank.

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 60–63. Acanthosoma haemorrhoidale formosanum subsp. nov. 60–61 – male (holotype); 62–63 – female (paratype, right antennal segment IV reconstructed digitally). Scales in mm.