Onychotrechus rhexenor Kirkaldy, 1903

Kment, Petr & Carapezza, Attilio, 2022, Heteroptera (Hemiptera) of the Socotra Archipelago I: Introduction, Nepomorpha, Gerromorpha and Leptopodomorpha, Acta Entomologica Musei Nationalis Pragae (Acta. Ent. Mus. Natl. Pragae) 62 (2), pp. 475-519 : 500-501

Onychotrechus rhexenor Kirkaldy, 1903

( Fig. 46 )

Onychotrechus rhexenor Kirkaldy, 1903b: 44–45 (original description). Holotype: ♂ (macropterous), India: Karnataka, Kanara (BMNH).

Published record. ANDERSEN (1980): Hadibo [= Hadiboh] plain, 2000 ft [= 610 m a.s.l.] (BMNH). WRANIK (2003, as Gerris sp. larva): Socotra (no exact locality).

Material examined. SOCOTRA: Firmihin, [ca. 390–760 m a.s.l.], iii.1999, 1 ♂ (ap), W. Wranik lgt. ( WWRG → NMPC).

Identification. ANDERSEN (1980) (key, redescription, larva, figures).

Habitat. There are only two specimens recorded from Socotra, referring to the medium-elevation and montane zone, but without details on sampled habitat ( ANDERSEN 1980, this paper). A hygropetric species; in India it was found resting or walking on wet, inclined and seeping rock faces and on rocks close to mountain streams, covered by algae and a thin sheet of trickling water. Both larvae and copulating adults were collected on wet cliffs far from surface waters. When disturbed the insects jump from rock to rock, and only rarely were captured by sweeping net through water. Both specimens from Socotra are apterous, but in South India the macropterous morph occurred with high frequency and was also taken at light ( ANDERSEN 1980).

Distribution. Palaearctic Region: Socotra ( ANDERSEN 1980, 1995). Oriental Region: India: Chhattisgarh, Karnataka, Kerala, Maharashtra, Rajasthan, Tamil Nadu ( KIRKALDY 1903b, ANDERSEN 1980, THIRUMALAI 2002, SUBRAMANIAN et al. 2014, JEHAMALAR & CHANDRA 2016).

Note. Onychotrechus rhexenor as well as all other members of Eotrechinae are confined exclusively to the Oriental Region ( ANDERSEN 1980, 1982: fig. 622). The extension of the species to Socotra is very unusual, so doubts about the authenticity of the material occurred. However, finding the apterous male from Firmihin in the collection of Wolgang Wranik, which included only materials from Socotra and continental Yemen, makes the possibility of mislabelling of both existing specimens highly unlikely. The colouration of the Firmihin specimen fits the illustrations of O. rhexenor by ANDERSEN (1980: fig. 14) but application of the tarsal characters was problematic; we follow the opinion of ANDERSEN (1980) in identifying the Socotran specimens as O. rhexenor , but a future taxonomic revision is needed.

Figures

Figs 45–46. 45 – Limnogonus cereiventris (Signoret, 1862): 45 – macropterous ♀, wadi Zerig (body length 9.12 mm). 46 – Onychotrechus rhexenor Kirkaldy, 1903, apterous ♂, Firmihin (4.71 mm). (Orig. P. Kment).