Picromerus griseus (Dallas, 1851)

Souma, Jun, Utagawa, Akihiro & Ishikawa, Tadashi, 2023, First record of the predatory stink bug species Picromerus griseus (Dallas) (Hemiptera, Heteroptera, Pentatomidae, Asopinae) in Japan, with an illustrated key to the Japanese species of the genus Picromerus Amyot & Serville, Biodiversity Data Journal 11, pp. 105293-105293 : 105293

Picromerus griseus (Dallas, 1851)

Picromerus griseus Canthecona grisea Dallas, 1851 - Dallas (1851): 92, new species and description.

Picromerus griseus Picromerus obtusus Walker, 1867 - Walker (1867): 133, new species and description; Schouteden (1907): 25, synonymised with Picromerus griseus .

Picromerus griseus Picromerus nigrivitta Walker, 1867 - Walker (1867): 133, new species and description; Distant (1900): 58, synonymised with Picromerus obtusus .

Picromerus griseus Picromerus sundanus Breddin, 1902 - Breddin (1902): 96, new species and description; Thomas (1994): 192, synonymised with Picromerus griseus . Gaedike (1971): 100, designation of lectotype.

Picromerus griseus Picromerus griseus Schouteden, 1907 - Schouteden (1907): 25, new combination; Thomas (1994): 192, catalogue and distribution; Rider (2006): 243, catalogue and distribution; Zhao et al. (2013): 73, diagnosis, figure, and distribution; Zheng and Lin (2013): 145, figure and distribution.

Materials

Type status: Other material. Occurrence: recordedBy: Akihiro Utagawa; individualCount: 1; sex: male; lifeStage: adult; occurrenceID: B9C40A18-594B-59E7-BCA1-4AB46599AC3E; Taxon : scientificName: Picromerus griseus (Dallas, 1851); namePublishedIn: 1851; kingdom: Animalia ; phylum: Arthropoda ; class: Insecta ; order: Hemiptera ; family: Pentatomidae ; genus: Picromerus ; specificEpithet: griseus; scientificNameAuthorship: Dallas ; Location : islandGroup: Ryukyu Islands ; island: Ishigaki Island ; country: Japan; countryCode: Okinawa; municipality: Ishigaki-shi ; locality: Sakieda ; decimalLatitude: 24.438250; decimalLongitude: 124.102167; geodeticDatum: WGS84; Identification : identifiedBy: Jun Souma ; dateIdentified: 2023; Event : samplingProtocol: none specified; eventDate: 08-11-2022; Record Level: institutionCode: TUA; basisOfRecord: PreservedSpecimen

Diagnosis

Picromerus griseus can be distinguished from other species of the genus using a combination of the following characteristics: head, pronotum, scutellum and femora uniformly brown (Fig. 1 a, b); humeral angle of pronotum strongly protruding laterad, acute at apex, posteriorly with a distinct subapical prominence (Fig. 2 a); posterior margin of genital capsule weakly curved inwards in middle part (Fig. 4 a); and paramere weakly curved inwards in apical part in dorsal and caudal views, distinctly concave along inner margin in dorsolateral view (Figs 3 a, 5 a, 6 a).

Distribution

Japan (Ryukyu Islands: Ishigaki Island), Bangladesh, Bhutan, China, Indonesia, Myanmar, Pakistan, Taiwan ( Thomas 1994, Rider 2006, Zhao et al. 2013, Zheng and Lin 2013, present study).

The discovery of Picromerus griseus from Japan represents the easternmost record of the species.

Biology

Picromerus griseus was collected from grasslands surrounding fields in Japan. In Japan, adult s are collected in November; however, the nymphs are unknown.

Taxon discussion

The specimen recorded above (Figs 1 a, b, 2 a, 3 a, 4 a, 5 a, 6 a) matched the photographs and descriptions ( Dallas 1851, Zhao et al. 2013) of Picromerus griseus in terms of morphological characteristics, including the humeral angle and male genitalia. The Japanese specimen was identified as P. griseus using a key for the East Asian species of Picromerus ( Zhao et al. 2013), based on its morphological characteristics. However, the colouration of the connexivum of the Japanese specimen (yellow and black) did not match the above-mentioned key (entirely black). To the best of our knowledge, Japanese populations of P. bidens and P. lewisi show a high degree of intraspecific variation in the colouration of the connexivum (yellow and black to entirely black) (Figs 1 c, d, 7). In conclusion, we did not use the colouration of the connexivum as a diagnostic characteristic of Picromerus and identified the Japanese specimen as P. griseus , based on the shape of the humeral angle and male genitalia.