Emmidolium excavatum Orchymont 1937
Creators: name: Fikáček, Martin
Publisher: name: Zenodo
Year: 2007
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Coleoptera
Hydrophilidae
Emmidolium
Emmidolium excavatum

description: Emmidolium excavatum Orchymont, 1937
Emmidolium excavatum Orchymont, 1937: 467. Type locality: Vietnam, Tonkin, Hoa Binh.
Emmidolium excavatum: HANSEN (1991): generic revision; HANSEN (1999): catalogue; HANSEN (2004): catalogue; HORI & SATÔ (2002): redescription, distributional records; SATÔ & HORI (2006): distributional records.
Type material examined. Hol ot ype: ♀, ‘ ♀ // Hoa – Binh (Tonkin) / A. de Cooman // A. d’Orchymont det. / Emmidolium / excavatum. // TYPE’ (IRSN).
Additional material examined. UNITED ARAB EMIRATES: ABU DHABI EMIRATE, National Avian Research Centre near Sweihan, 24°24′N 55°26′E, 29.xii.2005 - 22.i.2006, light traps (UAE 7055), 1 ♀, A. van Harten lgt.; Shar jah Emir at e, Sharjah Desert Park, 25°17′N 55°42′E, 6.-30.iv.2005, light trap (UAE 1878), 1 J, A.van Harten lgt. (NMPC). REPUBLIC OF THE CONGO: Congo – Brazzaville, Mt. Fouari reservation near Gabon, Soilzoological expedition, 14.xii.1963, singled and sifted from buffalo dung, No. 465, 1 J 2 ♀♀, 3 unsexed specimens, Endrödy-Younga lgt. (HMNH, NMPC, KSEM).
Morphology. Examined specimens from Africa and the United Arab Emirates are identical in external characters, coloration and the morphology of the aedeagus (Figs. 1-4). The only difference was found in the shape of the apical part of median projection of male sternite 9, which is wider and more excised in the male from Congo (Figs. 5-6). As the projection is very weakly sclerotized and the specimens correspond to each other in all other characters including the morphology of the aedeagus, I consider this difference as intraspecific variability. Externally, all examined specimens completely correspond with the holotype. The aedeagus of the specimen from the Ryukyu Islands figured by HORI & SATÔ (2002) also seems to be identical with the specimens examined in this study. In contrast to the ‘distinctly chagreened ventral surface’ mentioned by HORI & SATÔ (2002), all examined specimens including the holotype lack any microsculpture on the median portions of prosternum, meso- and metaventrite (the interstices are opaque but lack any trace of microsculpture under 90× magnification). The phallobase is distinctly asymmetrical in all specimens examined (male genitalia were mentioned as symmetrical but drawn with an asymmetrical phallobase by HORI & SATÔ (2002)).
Bionomics. Most of the known specimens were collected in the dung of various herbivorous mammals (cows: HORI & SATÔ (2002), SATÔ & HORI (2006); buffalo: present record from the Republic of Congo; elephants: HANSEN (1991)). Similar to other dung-inhabiting Hydrophilidae, E. excavatum is a good flier and can be attracted to light (present record from the United Arab Emirates).
Distribution. Reliably recorded from the Oriental region (Vietnam, Taiwan, Ryukyu Islands), Palaearctic region (United Arab Emirates) and Afrotropical region (Republic of the Congo) (Fig. 7). Previous records from Indonesia and Africa (HANSEN 1991) most probably also concern this species but need confirmation.
description: Published as part of Fikáček, Martin, 2007, Emmidolium excavatum Orchymont (Coleoptera: Hydrophilidae: Sphaeridiinae) confirmed in Africa and the Arabian peninsula, pp. 117-122 in Acta Entomologica Musei Nationalis Pragae 47 on pages 118-120, DOI: 10.5281/zenodo.5328110