Tumidusternus, a new genus of Aspidimerini from China (Coleoptera, Coccinellidae)

Abstract Tumidusternus gen. n., along with Tumidusternus fujianensis sp. n. (Coleoptera, Coccinellidae, Aspidimerini) from China is described and illustrated. A key to the tribe Aspidimerini is given.

During our recent study on Aspidimerini, an unusual species was discovered, which prosternum is extremely tumid, highly raised above the ventral surface. A further comparison of more characters (e.g. prosternum, mentum, antenna and legs) with other genera of Aspidimerini revealed that this species is distinctive. Hence, a new genus, Tumidusternus gen. n., is here proposed to accommodate this unusual species.

Material and methods
All studied materials were collected from China. Type specimens designated in the present paper are deposited in the Department of Entomology, South China Agriculture University, Guangzhou and the Institute of Zoology (IOZ), Chinese Academy of Science, Beijing.
External morphology was observed with a stereomicroscope (SteREO Discovery V20, Zeiss). Measurements were made using an ocular micrometer attached to the stereomicroscope as follows: (TL) total length, from apical margin of clypeus to apex of elytra; (TW) total width, across both elytra at widest part; (TH) total height, through the highest point of elytra to metaventrite; (HW) head width, including eyes; (PL) pronotal length, from the middle of anterior margin to the base of pronotum; (PW) pronotal width at widest part; (EL) elytral length, along the suture, from the apex to the base including the scutellum; (EW) elytral width, across both elytra at widest part; (ID) interocular distance, nearest distance between two eyes. Male and female genitalia were dissected, cleared in 10% solution of NaOH by boiling for several minutes, and examined with an Olympus BX51 compound microscope. Images were photographed with digital cameras (AxioCam HRc and Coolsnap-Procf & CRI Micro*Color). The software AxioVision Rel. 4.8 and Image-Pro Plus 5.1 were used to capture images from both cameras, images were cleaned up and laid out in plates with Adobe Photoshop CS5. Morphological terms follow Ślipiński (2007) and Ślipiński and Tomaszewska (2010 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. 1a-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.
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.  1a-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 ac-commodate apices of mid and hind femora (Fig. 2d). Wings well developed. Legs with trochanters and femora extremely broad and flattened, forming together trochanterfemur 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. 1n-o). Tibia and tarsus can be completely hidden under the trochanterfemur club for protection. Tibia flattened, outer margins with groove for receiving the folded tarsus, tarsi 3-segmented, tarsal claws bifid.
Male genitalia. Penis slender, curved at basal half, apex pointed (Fig. 2f). Penis capsule with inner arm slightly longer and thinner than outer one. Tegminal strut as long as main part of the tegmen. Parameres 2 times of phallobase length and 1.5 times of penis guide length, apical half with long sparse setae (Fig. 2g-h). Penis guide 4 times as long as wide, parallel for basal 3/4, then convergent to rounded apex (Fig. 2i).
Etymology. The specific name refers to the holotype locality, Fujian, China. Distribution. China (Fujian, Guangdong).