Ryssonotus MacLeay, 1819

Reid, C. A. M. & Beatson, M., 2016, Revision of the stag beetle genus Ryssonotus MacLeay (Coleoptera: Lucanidae), with descriptions of a new genus and three new species, Zootaxa 4150 (1), pp. 1-39 : 2-3

Ryssonotus MacLeay, 1819

Ryssonotus MacLeay 1819: 98 ; Thorpe 2001: 22; Holloway 2007: 115. Rhyssonotus Agassiz, 1846: 329 , unjustified emendation.

Type species. Lucanus nebulosus Kirby, 1819 , by monotypy.

Diagnostic description. Adult. Length: excluding mandibles: 12–26 mm; including mandibles: 15–33 mm. Upper surface densely microreticulate, with mottled colour pattern; ventral setae multifid; eyes completely divided by expanded canthus, eye segments separated by less than half upper eye segment height in lateral view; antennae geniculate, with antennomeres 1–5 sparsely setose and symmetrical, and antennomeres 6–10 partly densely setose and asymmetric, forming a loose club; mandibles strongly punctured, inner faces densely setose; side of head without genal lobe; upper surface of head with median tubercle, without deep pit at base; mentum relatively small, semicircular, impunctate and membranous; pregular area feebly convex, with slightly convergent sides; pronotum with foveolate depressions; posterior corners of pronotum not margined, but also not deeply concavely excavate; prosternal process strongly arched and visible between coxae; lateral margins of female pronotum almost even, with a few irregularly spaced small indentations about middle, but not distinctly crenulate; lateral margins of elytra not explanate; mesoventrite process anteriorly excavate; tarsal empodium short, much less than half length of claws; aedeagus with everted unbranched endophallus; dorsal edge of parameres not notched; male paraproct fused dorsally not split into two sclerites; proctiger of ovipositor weakly sclerotised and quadrate, paraproct complete; vaginal palp conico-cylindrical and thickly setose; spermatheca membranous.

Larva. The following diagnosis is based on examined material from the Dorrigo area, New South Wales ( AMS, collected Reid & Day), North Queensland ( ANIC, collected Brooke & Parrott), and the published description ( Lawrence 1981).

Mandible with 1 apical tooth plus 4 internal subapical (scissorial) teeth; tibiotarsus reduced to a small lobe, length equal to width at base; no dorsal anal lobe, lateral lobes with well-defined ovoid pads, margined, smooth and glabrous; 10th abdominal segment dorsally foreshortened, with raster of moderately dense, very short, outwardly directed setae; metatrochanteral stridulatory file (pars stridens) present as a single ridge of about 16 sparse, almost quadrate granules ( Lawrence 1981: fig. 4); mesocoxal stridulatory file (pars stridens) present as a fine line of densely packed small transverse granules, ending in a basal oval field of scattered minute granules.

Notes. The original spelling of this genus was emended by Agassiz (1846) to Rhyssonotus . Prior use of Ryssonotus was well-established ( Kirby & Spence 1826), but the emended name has become standard in Australian literature ( Moore & Cassis 1992, updated by Calder 2010; Lawrence & Ślipiński 2013). However, outside Australia, use of Ryssonotus has prevailed ( Thorpe 2001; Holloway 2007; Bouchard et al. 2011). As Agassiz’ action was an unjustified emendation (International Commission on Zoological Nomenclature 1999, Article 33.2.3) and its use has arguably not prevailed in a global context (Article 33.2.3.1), we follow Holloway (2007) and use Ryssonotus , consigning Rhyssonotus Agassiz, 1846 to junior objective synonymy (Article 33.2.3).

The name Lucanus foveolatus Thunberg, 1806 , hitherto considered a probable senior synonym of R. nebulosus ( Parry 1870; Gourlay 1954; Moore & Cassis 1992), refers to the North American species Lucanus capreolus ( Linnaeus, 1763) (new synonym) and is therefore unlikely to have been collected in Australia (photograph of holotype examined, courtesy UUS).

The type species of Ryssonotus , R. nebulosus , differs markedly from all other species hitherto placed in this genus. These other species, which do not belong to any genus from elsewhere, for example the potentially related lucanid faunas of New Zealand ( Holloway 2007), Africa ( Switala et al. 2014), and South America ( Mizunuma and Nagai 1994; Paulsen 2010a), are removed and placed in a new genus, defined below. The name Ryssonotus is retained for R. nebulosus , endemic to Australia but widespread on the eastern margin of the continent.