Emmidolium excavatum Orchymont, 1937

Fikáček, Martin, 2007, Emmidolium excavatum Orchymont (Coleoptera: Hydrophilidae: Sphaeridiinae) confirmed in Africa and the Arabian peninsula, Acta Entomologica Musei Nationalis Pragae 47, pp. 117-122 : 118-120

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.

Figures

Figs. 1-6. Emmidolium excavatum Orchymont, 1937.1-2 – habitus, specimen from the Republic of the Congo: 1 – dorsal view; 2 – ventral view. 3-4 – aedeagus, specimen from Sharjah Desert Park (UAE): 3 – dorsal view; 4 – lateral view. 5-6 – male sternite 9: 5 – specimen from Sharjah Desert Park (UAE); 6 – specimen from Congo.

Fig. 7. Known distribution of Emmidolium excavatum Orchymont, 1937.