Tumidusternus Huo & Ren

Huo, Lizhi, Li, Wenjing, Chen, Xiaosheng, Wang, Xingmin & Ren, Shunxiang, 2015, Tumidusternus, a new genus of Aspidimerini from China (Coleoptera, Coccinellidae), ZooKeys 511, pp. 81-87 : 82

Taxon classification Animalia Coleoptera Coccinellidae

Tumidusternus Huo & Ren gen. n. Figures 1, 2

Type species.

Tumidusternus fujianensis Huo & Ren, sp. n.

Diagnosis.

Tumidusternus can be easily distinguished from other genera of Aspidimerini by middle part of prosternum extremely tumid, highly raised above the ventral surface (Fig. 1 a–d) and anterior margin of mentum triangularly emarginate (Fig. 1g). While in Acarinus and Cryptogonus , middle part of prosternum is flat and anterior margin of mentum has a small, rectangular notch at middle; in Aspidimerus , middle part of prosternum is evenly convex, but not tumid and anterior margin of mentum is truncate, without a notch or an emargination; in Pseudaspidimerus , only area of the prosternum between the parallel carinae lies at a higher level than the lateral parts outside the carinae, and anterior margin of mentum possesses a small, triangular emargination at middle.

Description.

Body small (TL: 2.73-2.95 mm), oblong oval (TL/TW=1.25-1.29) and moderately convex, dorsum finely punctate and pubescent.

Head. Head transverse, brown. Eyes large, rounded and finely faceted, with sparse interfacetal setae. Clypeus widely emarginate, partially covering labrum. Antenna (Fig. 1h) very short, 9-segmented, with sparse long setae at inner side, hidden in antennal grooves, invisible from above and partially visible from below. Scape large, transversely oval, 1.5 times as wide as long, pedicel smaller and subtriangular, Antennal club fusiform, distinctly longer than width of scape, terminal antennomere acutely conical, as long as penultimate one. Maxilla (Fig. 1f) with cardo and stipes subtriangular. Maxillary palp 3-segmented, always hidden under the cardo and stipes for protection, terminal palpomere securiform. Mentum (Fig. 1g) subtrapezoidal, with anterior margin widely triangularly emarginate and posterior margin slightly incurved, partially covering labium. Labial palp (Fig. 1g) 2-segmented, basal palpomere gradually thicker to apex, apex 2 times as wide as base of terminal palpomere. Terminal palpomere cylindrical, slightly tapering apically, rounded at apex. Mandible (Fig. 1e) broad with apex bifid and basal tooth pointed. Labrum transverse (Fig. 1i), 2.0-2.5 times as long as wide, covered with long and sparse setae.

Prothorax. Prothorax convex and transverse, anterior margin deeply emarginate, lateral margins arcuate with anterior corners rounded and posterior corners nearly orthogonal. Prosternum T-shaped with middle part extremely tumid, highly raised above ventral surface of the body, with surface coarsely punctate and densely pubescent (Fig. 1 a–d). Each side folded down constituting a prosternal fold (Fig. 1c). Anterior margin of prosternum with broad border well visible in front view (Fig. 1d). Procoxal cavity distinctly transverse, longitudinal diameter shorter than prosternum in front of coxae. Prosternal process broad, width equal to length of prosternum in front of coxae, with apex rounded. Carinae parallel along 3/4 length of prosternal process then confluent with the tumid part of prosternum (Fig. 1c).

Prerothorax. Mesoventrite (Fig. 1j) with mesoventral process 0.5 times as long as longitudinal mesocoxal diameter; anterior margin widely emarginate and concave at middle to receive prosternal process; mesoventral process as broad as mesocoxal diameter; meso-metaventral junction slightly arcuate anteriorly. Metaventral postcoxal lines joined medially, recurved and complete laterally. Discrimen long but incomplete. Metendosternite stalk 0.5 times as long as broad, tendons separated by less than width of stalk and situated on laminae (Fig. 1l). Scutellum small, subtriangular, black. Elytra moderately convex. Humeral calli weakly visible. Elytral epipleuron incomplete, gradually narrowing from base to 3/5 of elytral length, with clearly delimited cavities to accommodate apices of mid and hind femora (Fig. 2d). Wings well developed. Legs with trochanters and femora extremely broad and flattened, forming together trochanter-femur clubs. Front leg with trochanter-femur club very broad, inner margin partially straight (Fig. 1m); mid and hind leg with trochanter-femur club oval, inner margin arcuate (Fig. 1 n–o). Tibia and tarsus can be completely hidden under the trochanter-femur club for protection. Tibia flattened, outer margins with groove for receiving the folded tarsus, tarsi 3-segmented, tarsal claws bifid.

Abdomen. Abdomen with 6 ventrites in both sexes. Ventrite 1 distinctly longer than ventrite 2, at middle 4-5 times as long as ventrite 2 and laterally slightly longer than ventrite 2. Ventrite 2 short at middle, 0.5 times length of lateral margin. Ventrites 3-4 with margins straight, equal in length. Ventrite 5-6 longer than 3-4. Ventrite 6 weakly emarginate apically in male (Fig. 1k) and rounded in female. Postcoxal lines deep but not merging with hind margin of ventrite, laterally incomplete.

Etymology.

The generic name is derived from Latin tumidus and sternum, referring to its tumid prosternum. Gender masculine.