Tomogenius Marseul, 1862

Lackner, Tomas & Leschen, Richard A. B., 2017, A monograph of the Australopacific Saprininae (Coleoptera, Histeridae), ZooKeys 689, pp. 1-263 : 174-176

Tomogenius Marseul, 1862 Figs 619, 620-628, 629-637, 638, 639-647, 648-650, 651-659, 660, 661-669, 670-678, 679, 680-688, 689-697, 698, 699-707, 708-715, 716, 717-722, 723-731, 732, 733-741, 742-750, 755, 766, 767

Tomogenius Marseul, 1862: 499. Type species Saprinus incisisternus Marseul, 1862 (= Tomogenius incisus (Erichson, 1842)), by monotypy.

Diagnosis.

Cuticle brown to black; elytra in one species with faint bluish hue; frontal, supraorbital striae absent (in T. papuaensis supraorbital striae vaguely present); lacinial hook present; antennal club with two oval sensory areas dorsally and two slit-like pits ventrally. Elytral epipleuron with double marginal epipleural stria; elytra with short hooked appendix between fourth dorsal and sutural striae (absent in T. papuaensis ); pronotal depressions absent; prosternum apically with two large deep foveae, separated by thin ‘bridge’ formed by the apex of prosternal process (in case of one species widely separated); lateral costa of antennal groove reaching prosternal process (except in T. papuaensis ), but not elevated; ninth tergite of male genitalia divided longitudinally.

Biology.

Species of the genus Tomogenius are found in bat guano as well as bird’s nests: T. latipes has been collected in the guano of the New Zealand lesser short-tailed bat ( Mystacina tuberculata Gray, 1843) and in the nest of the New Zealand Kingfisher Halcyon sancta vagans (Gray, 1844). Tomogenius australis and T. kuscheli have been found in petrel burrows ( Dahlgren 1976; T. kuscheli has also been found in the nest of Fluttering Shearwater, Puffinus gavia (Forster, 1844)); T. latipes has been found in the nest of Kaka ( Nestor meridionalis Gmelin, 1788; Jackson 1963), as well as sifted from the forest litter; T. ripicola was collected in bat guano and under a sheep carcass.

Distribution.

The genus is endemic for the Australopacific Region: seven species are currently known from Australia, New Zealand and New Guinea ( Mazur 2011; Figs 766-767).

Remarks.

Tomogenius is most similar to the Holarctic genus Gnathoncus Jacquelin du Val, 1857 from which it differs chiefly by larger body size, different arrangement of sensory structures of antennal club, lateral costa of antennal groove not being elevated and the presence of two large median foveae situated at the apex of prosternal process. On the other hand, it shares with Gnathoncus several putative synapomorphies: absent both frontal and supraorbital striae, double marginal epipleural stria, presence of characteristic short, hooked appendix between fourth dorsal and sutural stria (except T. papuaensis ), presence of lacinial hook (=uncus) of maxilla and longitudinally divided ninth tergite of male genitalia. Tomogenius and Gnathoncus are both found mostly in nests of birds and/or mammals, with some species also found in caves presumably feeding on arthropod larvae present on guano or carrion. They represent an amphi-polar clade with few species from the tropics (only two of the 25 currently known species of Gnathoncus are present in the Old World tropics; see Mazur 2011 and Vienna and Ratto 2013). In the published phylogenetic analysis of the senior author ( Lackner 2014d), Tomogenius and Gnathoncus were recovered as sister taxa, supported by three ‘strong’ synapomorphies. Together with the genera Erebidus Reichardt, 1941 and Myrmetes Marseul, 1862 they were placed near the root of the tree; this position was further confirmed by the ongoing molecular studies (Lackner, unpublished).

Key to Australopacific species of Tomogenius Marseul, 1862