Unicornileptura Bi, Chen & N. Ohbayashi, 2022

Bi, Wen-Xuan, Chen, Chang-Chin & Ohbayashi, Nobuo, 2022, Unicornileptura gen. nov., a unique lepturine genus from China (Coleoptera, Cerambycidae, Lepturinae, Lepturini), Zootaxa 5129 (1), pp. 145-150 : 146

Unicornileptura Bi, Chen & N. Ohbayashi , gen. nov.

Type species: Unicornileptura emeiensis Bi, Chen & N. Ohbayashi sp. nov.

Description. Body narrowly elongate. Head short with obliquely inclined mouthparts, broadest at across the eyes; frons steep and narrow, with a vague median ridge reaching vertex; genae very short; postvertex of male protruding backward to form a short horn in lateral view ( Fig. 8a ), triangular shaped in frontal view ( Fig. 8b ), almost reaching anterior margin of pronotum; temples moderately developed, shorter than longitudinal eye diameter, roundly constricted to neck. Eyes almost entire, finely facetted; interocular space wider than distance between antennal cavities. Maxillary palpus with fusiform terminal segment, about 1.5 times as long as the penultimate segment. Antennae inserted near anterior margin of eyes, reaching or exceeding elytral midlength; scape clavate, abruptly bent down near apex; flagellum filiform with apices of basal 5 flagellomeres slightly thickened, first flagellomere longer than second, shorter than third.

Pronotum trapezoid, nearly as broad as head; sides weakly rounded with obtusely angulate or broadly rounded apical corner and short acute hind angles; hind angles short and acute; disk gently convex. Prosternum without transverse excavation between procoxae and anterior margin; procoxal cavities widely opened posteriorly; prosternal process very narrow with slightly dilated apex. Mesosternal process gradually declivous anteriorly in lateral view. Mesocoxal cavity open to episternum.

Elytra elongate, more than 3 times as long as humeral width, more than 2.5 times as long as head and pronotum combined; slightly narrowed apically in male, subparallel sided in female, then roundly narrowed to apices; disk metallic green or blue. Abdomen completely covered by elytra; abdominal ventrites I about 1.5 times as long as II to V respectively. Legs moderately long and slender; femora weakly clavate; hind tarsi with first tarsomere slightly longer than the following two tarsomeres combined.

Etymology. From the combination of Latin ūnicornis, meaning one-horned and leptura, the name of the type genus of Lepturini . Gender feminine.

Distribution. China: Sichuan; Hubei.

Remarks. This new genus should be placed into Lepturini by the feature of prothorax without transverse groove or depression in front of coxal cavities ( Gressitt, 1951; Villiers, 1978; Tsherepanov, 1990; Bense, 1995; etc.). It superficially resembles Grammoptera Audinet-Serville, 1835 especially the group of the subgenus Neoencyclops regarding their overall habitus e.g. slender body, metallic colored elytra and similar proportion of body, but it can be readily distinguished from the latter by the curved scape, transverse pronotum and extremely elongate elytra. And fundamentally, it is rather unique among the Asia lepturine genera by its head significantly sexually dimorphic, provided with a cranial horn in male ( Fig. 8a ) which absent in female ( Fig. 9a ).

The presence of horn-shaped projection of head mostly found in male was rarely reported from worldwide Cerambycidae and currently limited to some lamiine tribe which originated from different portions, e.g. single postclypeal horn in Momisis of Astathini or paired in Mauesia of Mauesiini; mandibular horns in Chariesthoides of Tragocephalini; antennal tubercular horns in some taxon of Onciderini ( Švácha & Lawrence, 2014) and also a postclypeal horn in Afirican genus Prosopocera of Prosopocerini ( Adlbauer et al., 2015) . The cranial specialized horn found in Unicornileptura gen. nov. probably the first discover of such structure in Lepturinae , or even firstly reported from the whole group of longicorn beetles. Unfortunately such unique feature was recognized later in the laboratory based on dry specimens, its biological or ecological significance remains uncertain and requires further field observation.

Figures

FIGURES 8–13. Head and pronotum of Unicornileptura spp. 8–11, U. emeiensis sp. nov.; 12,13, U. laticollis sp. nov. 8, 9, head in lateral view (a) and frontal view (b); 10–13, pronotum in dorsal view. 8, 10, 12, male; 9, 11, 13, female.