Umbothynnus, Brown, Graham, 2008

Brown, Graham, 2008, Umbothynnus, a newly recognised genus for the Rhagigaster alexius Guérin group of species (Hymenoptera: Tiphiidae: Thynninae: Rhagigasterini) from northern Australia, Zootaxa 1933, pp. 43-58 : 44-45

Umbothynnus , gen. nov.

Type species. Umbothynnus katherinensis n. sp.

Diagnosis. Male. Small (body 8–12 mm), black; metasoma long, narrow, cylindrical, segments strongly constricted (fig. 1); antennal prominence (viewed dorsally) projecting and rounded above each antennal insertion (fig. 2); lateral margins of T7 usually straight, enclosing a smooth impunctate medial area, never with a U-shaped carina.

Head. Wider than long (viewed anteriorly); clypeus medially raised and convex at least basally, apical margin truncate to emarginate; mandibles bidentate, not tuberculate; antennae short, segments at least 2x longer than wide; antennal prominence strongly produced (viewed dorsally) as two parallel-sided and apically obliquely truncate lobes, one above each antennal insertion; transverse frontal carina usually distinct but may be obscured by rugose-punctate microsculpture.

Mesosoma . Anterior margin of pronotum raised, usually carinate, weakly laterally produced; propodeum rounded; 2m-cu received distal to 1r-m on M by less than half length of 1r-m; metasoma cylindrical to elongate fusiform.

Metasoma. Long, narrow, cylindrical with segments strongly constricted; T1 oblique anteriorly, as wide as long; S1 medially raised; T7 convex, narrowly truncate, usually laterally carinate; hypopygium (S8) concave dorsally with strongly developed upwardly curved apical spine which has dorsal subapical spines (visible in profile), basal angles obtuse, rounded, angulate or absent; genitalia with basal ring strongly constricted basally and expanded apically so that the maximum width is greater than that of the basiparameres; parameres strongly laterally convex internally without being strongly narrowed apically; paramere-basiparamere suture distinct; basiparameres usually short medially; vosellae short and ending near the apex of the basiparameres; parapenal lobes and digitus absent.

Colour. Integument black; wings usually infuscate, more hyaline basally.

Female. Insufficiently known.

Remarks. The male is similar in appearance to Dimorphothynnus Turner , Rhagigaster and Rhytidothynnus. However, Rhytidothynnus and Umbothynnus are mostly small species with most species less than 12 mm in length but rarely up to 17 mm. Those of Dimorphothynnus and Rhagigaster are larger with ranges up to 23 mm (in Rhagigaster sensu stricto) or more, but rarely less than 12 mm in length.

Umbothynnus is further distinguished from Rhytidothynnus by the face wider than high and the anterior margin of the pronotum is often carinate.

There are insufficient females of Umbothynnus known to give a diagnosis or to compare these genera. Etymology. The prefix umbo - is derived from Latin and is a reference to the curved projections above the antennal insertions of the male. This character is distinctive within the Australian Rhagigasterini.