Trisunius, Assing, 2011

Assing, V., 2011, Trisunius gen. nov. from the southern East Palaearctic and the Oriental regions (Coleoptera: Staphylinidae: Paederinae: Medonina), Linzer biologische Beiträge 43 (1), pp. 195-220 : 196-197

Trisunius nov.gen.

T y p e s p e c i e s Trisunius spathulatus nov.sp.; present designation.

E t y m o l o g y: The name is composed of the Latin prefix tri- (three) - alluding to the trilobed ligula - and the generic name Sunius. The gender is masculine.

D e s c r i p t i o n: Body of rather small size, body length 2.7-4.0 mm. Forebody with very fine to moderately coarse punctation (finer than in Sunius) ( Figs 3 , 20 , 59 , 69 ); head and pronotum with or without ( Figs 3 , 20-21 , 59, 62 , 69, 75 ), elytra without microsculpture; pubescence short and indistinct. Head approximately as long as wide or weakly oblong; posterior angles moderately marked; neck almost half as wide as head (e.g., Figs 2 , 11-12 , 18-19 ). Eyes much shorter than postocular portion in dorsal view. Ventral aspect of head with or without microsculpture; gular sutures separated by a distance of nearly the width of antennnomere IV. Antenna of moderate length, of similar morphology as in Sunius ( Fig. 4 ). Labrum strongly transverse; anterior margin with deep Ushaped median incision, with a tooth-like projection on either side of this incision and usually with an additional tooth-like process laterally ( Figs 36 , 70 ). Maxillary palpus 4- jointed, preapical palpomere somewhat flattened and enlarged, barely twice as wide as long; apical palpomere needle-shaped and short ( Fig. 73 ). Labial palpus 3-jointed; apical palpomere needle-shaped ( Figs 5 , 61 , 74 ); ligula trilobed ( Fig. 60 ); left mandible with three, right mandible with three to five molar teeth ( Figs 71-72 ).

Pronotum noticeably oblong, slightly narrower than head; weakly tapering posteriad; posterior angles weakly marked; midline with more or less pronounced, narrow to broad impunctate band.

Elytra slightly to distinctly broader than pronotum, in some species subject to more or less pronounced dimorphisms. Legs short and with short tarsi. Protarsomeres I-IV distinctly dilated in both sexes. Mesotarsomeres II-IV broader than long. Metatarsus distinctly shorter than metatibia; metatarsomere I short, approximately as long as broad and only slightly longer than II, II-IV approximately as long as broad or even broader than long.

Abdomen widest at segment VI. Tergal surfaces with dense fine punctation and with fine microsculpture ( Fig. 76 ).

Ƌ: sternite VII with or without modified pubescence, in posterior portion with or without impression, posterior margin usually weakly concave in the middle (e.g., Figs 6 , 13 , 23 , 30 , 37 ); sternite VIII posteriorly with median incision of variable depth and width (e.g., 7, 14, 24, 31, 38); sternite IX relatively broad, usually 2.0-2.5 times as long as wide ( Figs 22 , 32 ). Aedeagus with basal portion more or less strongly produced ventrad in lateral view; ventral process of variable shape; dorso-apical structures more or less hookshaped; internal structures at most weakly sclerotized.

D i a g n o s i s: The genus is characterized and distinguished from other genera of Medonina resembling Sunius particularly by the trilobed ligula, the enlarged, flattened preapical maxillary palpomere, and the shape of the labrum. It is additionally distinguished from Sunius by the finer punctation of the forebody, the often more pronounced microsculpture of the head and pronotum, the distinctly dilated protarsomeres I-IV, as well as by the much shorter meso- and metatarsomeres. For illustrations of the mouthparts of Sunius see ASSING (2011).

D i v e r s i t y: The genus currently includes ten species, the vast majority of which (eight species) are known only from the Chinese province Yunnan.

D i s t r i b u t i o n: The currently known distribution ranges from Uttarranchal in the northwest to Thailand in the southeast. Although most species are distributed in regions assigned to the East Palaearctic region by LÖBL & SMETANA (2004), Trisunius appears to be an essentially Oriental genus, as can be inferred from its absence from high altitudes, as well as from the northern and central parts of China. The distributions of all the Chinese representatives are confined to Yunnan. The individual distributions of the species do not appear to be very restricted and strongly overlap, particularly so in Yunnan.

N a t u r a l h i s t o r y: Based on the data indicated on the labels attached to the examined specimens, the species primarily inhabit the litter layer of various forest habitats. On a few occasions, however, specimens were collected also in open (grassland) or shrub habitats. The altitudes range from 850 to 3000 m. On many occasions, several species were recorded to occur syntopically; in one locality as many as four Trisunius species were found. Adult beetles were collected in March, May-June, August- September, and November. Teneral specimens of several species were observed in August and September. At least some of the species are wing-dimorphic, this dimorphism in two species not only affecting the length of the elytra and the hind wings, but also the shape of the head and the size of the eyes.

Figures

Figs 1-9: Trisunius spathulatus nov.sp.: (1) habitus; (2) forebody; (3) median dorsal portion of head; (4) antenna; (5) labial palpi; (6) male sternite VII; (7) male sternite VIII; (8-9) aedeagus in lateral and in ventral view. Scale bars: 1: 1.0 mm; 2: 0.5 mm; 4, 6-7: 0.2 mm; 3, 5, 8-9: 0.1 mm.

Figs 17-26: Trisunius cultellatus nov.sp.: (17) habitus (micropterous morph); (18) forebody (micropterous morph); (19) forebody (macropterous morph); (20) median dorsal portion of head; (21) median dorsal portion of pronotum; (22) male sternite IX; (23) male sternite VII; (24) male sternite VIII; (25) aedeagus in lateral view; (26) ventral process of aedeagus in ventral view. Scale bars: 17: 1.0 mm; 18-19: 0.5 mm; 23-24: 0.2 mm; 20-22, 25-26: 0.1 mm.

Figs 57-66: Trisunius monticola (CAMERON): (57) habitus; (58) forebody; (59) median dorsal portion of head; (60-61) labium; (62) median dorsal portion of pronotum; (63) male sternite VII; (64) male sternite VIII; (65-66) aedeagus in lateral and in ventral view. Scale bars: 57: 1.0 mm; 58: 0.5 mm; 59, 62-64: 0.2 mm; 60-61, 65-66: 0.1 mm.

Figs 67-80: Trisunius thaicus nov.sp.: (67) habitus; (68) forebody; (69) median dorsal portion of head; (70) labrum; (71-72) mandibles; (73) maxilla; (74) labial palpi; (75) median dorsal portion of pronotum; (76) abdominal tergite VII; (77) male sternite VII; (78) male sternite VIII; (79-80) aedeagus in lateral and in ventral view. Scale bars: 67: 1.0 mm; 68: 0.5 mm; 69, 75-78: 0.2 mm; 70-74, 79-80: 0.1 mm.

Figs 10-16: Trisunius ligulatus nov.sp.: (10) habitus (macropterous morph); (11) forebody (macropterous morph); (12) forebody (submacropterous morph); (13) male sternite VII; (14) male sternite VIII; (15) aedeagus in lateral view; (16) ventral process of aedeagus in ventral view. Scale bars: 10: 1.0 mm; 11-12: 0.5 mm; 13-14: 0.2 mm; 15-16: 0.1 mm.

Figs 34-40: Trisunius iaculatus nov.sp.: (34) habitus; (35) forebody; (36) labrum; (37) male sternite VII; (38) male sternite VIII; (39) aedeagus in lateral view; (40) ventral process of aedeagus in ventral view. Scale bars: 34: 1.0 mm; 35: 0.5 mm; 37-38: 0.2 mm; 36, 39-40: 0.1 mm.

Figs 27-33: Trisunius discrepans nov.sp.: (27) habitus (micropterous morph); (28) forebody (micropterous morph); (29) forebody (macropterous morph); (30) male sternite VII; (31) male sternite VIII; (32) male sternite IX; (33) aedeagus in lateral view. Scale bars: 27: 1.0 mm; 28-29: 0.5 mm; 30-32: 0.2 mm; 33: 0.1 mm.