Type species: Yunnaniella mandian sp. n.

Description

Body (Fig. 1) of medium-small size; labrum with two long divergent lobules (Fig. 4a); maxillary palpi with long narrow segments, the 2^nd longer than 3^rd , the last shorter than 3^rdand subacute (Fig. 4b); labial palpi with 3^rdsegment longer than 2^nd , narrow (Fig. 4c); mandibles with narrow prostheca and only very small teeth, large lateral groove provided with two structures connected by a callous portion at their base, asymmetrical and matching when they are closed (Fig. 2); anterior tarsi narrow, the 3^rd tarsomere longer than the others, apart from the last (Fig. 4e) (posterior tarsi missing); antennae with long scape, 2^nd and 3^rd segments sub-equal in length, the following short and wide (Fig. 4d); frontal grooves absent; ocular grooves short, deep; gular sutures as in Fig. 4f; antesternal plate short, entire, with median protrusion; mesosternum flat, with very small median apophysis; pronotal epipleura thick; upper epipleural line very close to the lower one, parallel to this, truncated at half the length of the pronotum and not joining the lower line; male genital segment dorsally entire, with modified tergite; aedeagus large, with more or less symmetrical parameres.

Female unknown.

Etymology. The generic name refers to Yunnan.

Distribution. South Yunnan.

Remarks. This genus differs from all known genera of the tribe Xantholinini in the external characters listed above.

Material examined

Holotype ♂: China, S Yunnan, Xishuangbanna, 20 km SW Jinhong (recte Jinghong), vic. Man Dian (NNNR), 22.07.80N, 100.40.05E, 730 m, forest, A. Weigel 30.IX.2008 (Naturkundemuseum Erfurt).

Description

Length of body: 5.7; from anterior margin of head to posterior margin of elytra: 2.4 mm. Body shiny, dark reddish-brown, with light brown antennae and pale yellowish legs. Head sub-spherical, with broadly rounded sides from the eyes to the neck. Eyes small and flat. Surface of head with two parallel, irregular series of deep punctures on the clypeus and finer, not close punctation, apart from on a wide median band; the punctation denser on the lateral portion, provided with dense, erected setae. Pronotum of peculiar shape, dilated anteriad and narrow posteriad, with very oblique anterior margins and strongly sinuate sides, longer than head and as wide as it anteriad. Surface with irregular dorsal series of 12–13 punctures and lateral series difficult to define between other, deep, lateral punctures. Elytra large, a little dilated posteriad, as long as and much wider than pronotum, with rounded humeral angles. Surface with numerous punctures arranged in several series; the punctures fine and not close to each other. Abdomen with segments increasingly wider up to the 5^thvisible segment which is longer than the others. Surface with more or less evident, polygonal micro-reticulation at the base of the segments which are covered in dense punctation furnished with decumbent pubescence, particularly evident on the 5^th visible segment.

Male genital segment (Fig. 4g) with pleurae combined dorsally into a single sclerite, without any trace of a corresponding suture, with metamorphosed tergite; sternite as in Fig. 4h. Aedeagus (Fig. 4i) 2 mm long, ovoid, with truncate distal margin, with more or less symmetrical parameres furnished with small setae on the external margin; inner sac tubular, narrow and long, folded on itself and covered in fine spinulae.

Etymology. The specific epithet refers to the type locality, as a noun in apposition.

Distribution. The species is only known from the type locality.

Remarks. The particular conformation of the mandibles, combined with other significant exoskeletal characters, characterizes this genus. The two structures connected to the base of the mandibles are chitinized, asymmetrical and yet fit perfectly together when the mandibles are closed, as can be seen in the photographs (Figs 2–3). This absolutely excludes the possibility of it being a teratological phenomenon. Instead, this peculiar conformation may be related to particular, as yet unknown, feeding habits.