Orsunius, Assing, 2011

Assing, V., 2011, Orsunius gen. nov. from the Oriental region (Coleoptera: Staphylinidae: Paederinae: Medonina), Linzer biologische Beiträge 43 (1), pp. 221-244 : 222-224

Orsunius nov.gen.

T y p e s p e c i e s: Orsunius wunderlei nov.sp.; present designation.

E t y m o l o g y: The name is composed of the prefix Or- (from Oriental) and the generic name Sunius .

D e s c r i p t i o n: Body of small to moderate size, 3.2-5.0 mm long. Coloration of forebody reddish-yellow to reddish-brown, rarely dark-brown. Forebody with variable punctation and dorsally without microsculpture; pubescence sparse, suberect to erect.

Head of subquadrate to transversely rectangular shape, with pronounced posterior angles, and with moderately large and distinctly convex eyes; laterally mostly with numerous long black setae; posterior margin of head truncate or more or less distinctly concave in the middle; neck approximately half as broad as head or nearly so. Ventral aspect of head with microsculpture; gular sutures variable, often curved, very narrowly ( Fig. 34 ) to moderately broadly separated, often more widely separated posteriorly than anteriorly. Antenna ( Figs 4 , 30 ) moderately short to slender, preapical antennomeres as wide as long or weakly transverse. Labrum strongly transverse; anterior margin with U-shaped incision ( Figs 5 , 31 ), without tooth-like projections on either side of this incision. Mandibles ( Figs 12-13 , 60-61 ) apically rather long, slender, and acute; both left and right mandible with three pronounced molar teeth. Maxillary palpus ( Figs 6 , 32 , 62 ) slender, 4-jointed; preapical palpomere approximately 3 times as long as broad; apical palpomere needle-shaped and of variable length. Labial palpus ( Figs 7 , 63 ) 3-jointed; apical palpomere needle-shaped; ligula ( Figs 8 , 33 , 64 ) membranous and bilobed, each lobe with a subapical seta.

Pronotum weakly to distinctly transverse, slightly wider to slightly narrower than head, with subparallel lateral margins or posteriorly narrowed; only posterior two thirds or posterior half of lateral margins visible from above, anterior third or anterior half concealed by a protruding fold, but visible in lateral view; midline narrowly (e.g., Fig. 22 ) to broadly (e.g., Fig. 9 ) impunctate, rarely without impunctate band ( Fig. 35 ); margins mostly with some very long dark setae.

Elytra broader than pronotum and of variable length; lateral and posterior margins often with long dark setae. Hind wings present. Legs relatively short. Protarsi moderately to strongly dilated in both sexes and ventrally with dense setae. Metatarsus distinctly shorter than metatibia; metatarsomere I longer than II, but shorter than the combined length of II and III.

Abdomen widest at segments V/VI; tergal surfaces with dense fine punctation and with fine microsculpture composed of isodiametric and/or short transverse meshes ( Fig. 23 ); tergite VIII with palisade fringe; tergite IX not divided in the middle ( Fig. 40 ); tergite X very deeply incised posteriorly and with numerous long black setae ( Fig. 40 ).

Ƌ: sternite VII usually without modified pubescence and with weakly concave posterior margin ( Figs 38 , 44 ); sternite VIII mostly with dense, rarely with sparser unmodified pubescence, posterior margin usually truncate or with very shallow, rarely with moderately deep posterior excision; sternite IX slender, approximately 2.5-3.5 times as long as broad and with concavely excised posterior margin ( Fig. 46 ). Aedeagus slender, mostly with long, often more or less asymmetric, and sometimes laterally compressed ventral process; internal structures mostly weakly pronounced.

♀: sternite VII unmodified; posterior margin of sternite VIII convex.

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 shape and chaetotaxy of the labrum (similar to that of Neosclerus CAMERON ), the presence of three molar teeth on both mandibles, the relatively large head with sharply marked posterior angles, the morphology of the pronotum (lateral margins visible only in posterior two thirds or in posterior half when viewed from above), the pale coloration, the dilated protarsomeres I-IV, the morphology of the abdominal tergite X, the morphology of the aedeagus (long, slender, and often more or less asymmetric ventral process), as well as by the usually very shallow posterior excision of the male sternite VIII.

D i v e r s i t y: The genus currently includes nine named species. However, it seems likely that the true diversity is considerably greater. Most of the species described below are known only from a single locality. Orsunius immsi , on the other hand, has been recorded from northern India and from Malaysia (if the types of O. immsi and O. rubicundus are indeed conspecific). Moreover, all the examined species have hind wings and are apparently capable of dispersal by flight. These observations suggest that Orsunius species may be more or less widespread. Finally, two females representing two additional undescribed species were examined.

D i s t r i b u t i o n: The genus is apparently widespread in the Oriental region, its currently known distribution ranging from northern India (Uttaranchal) in the northwest to Indonesia and Malaysia in the southeast. According to LÖBL & SMETANA (2004), Uttaranchal and the Chinese province Yunnan are part of the East Palaearctic, but they are, in fact, situated in the transitional region between the East Palaearctic and the Oriental regions, where Oriental elements are predominant at low elevations.

N a t u r a l h i s t o r y: Rather little is known about the biology of the species. Based on the data indicated on the labels attached to the examined material, the species are found in leaf litter, compost, and in decaying wood at low to intermediate altitudes (100-1750 m).

Figures

Figs 27-37: Orsunius immsi (BERNHAUER) (lectotype of Medon rubicundus CAMERON): (27) habitus; (28) forebody; (29) median dorsal portion of head; (30) antenna; (31) labrum; (32) maxillary palpus; (33) ligula; (34) ventral aspect of head; (35) median dorsal portion of pronotum; (36- 37) aedeagus in lateral and in ventral view. Scale bars: 27: 1.0 mm; 28, 30: 0.5 mm; 29, 31-32, 34- 37: 0.2 mm; 33: 0.1 mm.

Figs 1-11: Orsunius wunderlei nov.sp.: (1) habitus; (2) forebody; (3) median dorsal portion of head; (4) antenna; (5) labrum; (6) maxilla; (7) labial palpus; (8) ligula; (9) median dorsal portion of pronotum; (10) aedeagus in lateral view; (11) apical portion of aedeagus in ventral view. Scale bars: 1: 1.0 mm; 2, 4: 0.5 mm; 3, 9-11: 0.2 mm; 5-8: 0.1 mm.

Figs 12-19: Orsunius wunderlei nov.sp. (12-14) and O. yunnanus nov.sp. (15-19): (12) left mandible; (13) right mandible; (14, 17) male sternite VIII; (15) habitus; (16) forebody; (18) aedeagus in lateral view; (19) apical portion of ventral process in lateral view. Scale bars: 15: 1.0 mm; 16: 0.5 mm; 12-14, 17-19: 0.2 mm.

Figs 57-69: Orsunius prolongatus nov.sp.: (57) forebody; (58) median dorsal portion of head; (59) labrum (paratype); (60-61) left and right mandible; (62) maxillary palpus; (63) labium; (64) ligula; (65) median dorsal portion of pronotum; (66) male sternite VIII; (67) aedeagus in lateral view; (68) apical portion of aedeagus in ventral view; (69) apex of ventral process in lateral view. Scale bars: 57: 0.5 mm; 58, 65-68: 0.2 mm; 59-64: 0.1 mm; 69: 0.05 mm.

Figs 20-26: Orsunius excisus nov.sp.: (20) forebody; (21) posterior median portion of head in dorsal view; (22) median dorsal portion of pronotum; (23) median portions of abdominal tergites VI and VII; (24) male sternite VIII; (25-26) aedeagus in lateral and in ventral view. Scale bars: 20: 0.5 mm; 24-26: 0.2 mm; 21-23: 0.1 mm.

Figs 38-40: Orsunius immsi (BERNHAUER) (lectotype of Medon rubicundus CAMERON): (38) posterior median portion of male sternite VII; (39) male sternite VIII; (40) male abdominal segments IX-X in dorsal view. Scale bar: 0.2 mm.

Figs 41-49: Orsunius parvexcisus nov.sp.: (41) forebody; (42) median dorsal portion of head; (43) median dorsal portion of pronotum; (44) male sternite VII; (45) male sternite VIII; (46) male sternite IX; (47-48) aedeagus in lateral view; (49) ventral process of aedeagus in ventral view. Scale bars: 41: 0.5 mm; 44-45, 47-49: 0.2 mm; 42-43, 46: 0.1 mm.