Megachile (Chelostomoda) guangxiense Niu, Wu & Zhu, 2012, sp. nov.

1. Megachile (Chelostomoda) guangxiense sp. nov.

(Figs. 1–10, Ƥ, holotype; Figs. 11–21, 37, 38, 3, allotype)

Diagnosis. This species can be distinguished from all other Chinese M. (Chelostomoda) species by the following combination of characters: both sexes with small body size, female clypeal median lobe with two tufts of yellowish-brown setae, apical white hair bands on T1–T3 narrower medially; male antenna short, only extending to apex of scutellum, first antennal flagellomere slightly broader than long, and less than half as long as second flagellomere; hind leg unmodified; S1 unmodified, unlike other species in the subgenus that posses a conspicuous medial projection.

Description. Female. Body length 7 mm (Figs. 1.2); head broader than long, HW: HL=80: 67 (Fig.3); gena narrower than eye in lateral view, GW: EW=20: 25 (Fig.4); width of metasoma equal to that of the tegula, MtW: TW=79: 79. First antennal flagellomere slightly longer than broad, second flagellomere broader than long, first flagellomere slightly longer than second, flagellomeres 3–9 approximately as long as broad, tenth flagellomere longer than broad (Fig. 5); clypeus broader than long, with round and shallow punctures, clypeal margin trilobed, median lobe broad and shallowly emarginated medially, with two tufts of yellowish-brown setae (Fig. 6); punctures on vertex and gena larger and denser than that of clypeus; mesoscutum and scutellum with round punctures (Fig. 7), size of punctures smaller than that of vertex; mesepisternum with round punctures, size of punctures roughly equal to that of mesoscutum; T1–T5 with punctures of different sizes; mandible roughly wide apically, with 5 teeth and a large incomplete cutting edge in second interspace only (Fig. 6); fore wing with two submarginal cells of roughly equal in length, basal vein roughly convex and meeting vein Cu at acute angle, 2nd m-cu meeting the apical margin of 2nd submarginal cell, marginal cell distal to stigma on costa longer than stigma; stigma over twice as long as broad, margin of stigma in first submarginal cell longer than width of stigma, prestigma much more than twice as long as broad; jugal lobe of hind wing less than half as long as vannal lobe, vein cu-v less than half as long as second abscissa of M+Cu; pronotal lobe carinate; axilla not produced posteriorly; metanotum without median spine; scuto-scutellar fovea absent; metasoma parallel sided; anterior surface of T1 strongly concave; T2–T4 with strong postgradular grooves, not fasciate; T1–T5 with apical bands of white hairs, bands of T1–T3 narrower at medially (Figs. 8, 9); T6 distinctly concave apically in lateral view (Fig. 9); S2–S5 with apical fasciae of white hair under scopa in lateral view; pygidial plate absent; middle and hind basitarsi distinctly shorter and narrower than corresponding tibiae, fore and middle tibiae with one spine on outer side, outer side of hind tibia without spine, outer surface of tibiae without tubercles; claws simple, without inner median tooth, arolia absent (Fig.10). Clypeus, mandible, vertex, frons, antenna, pronotal lobe, mesoscutum, scutellum, and legs black. Pubescence sparse; paraocular area, pronotal lobe, posterolateral surface of propodeum with longer plumose white hairs; apex of T6 with shorter and denser dull brownish-yellow hairs. Scopa white.

Male. Body length 6 mm (Figs. 11, 12); head round, head broader than long (Fig. 13), HW: HL=77:74; gena narrower than eye, GW: EW =19: 24; width of metasoma narrow than that of tegulae, MtW: TW=74: 81. Clypeus broader than long, with round and deep punctures; vertex, genae with round and denser punctures, punctures larger than those of clypeus; mesoscutum and scutellum with round punctures, size of punctures smaller than that of vertex; antenna short, extending to the apex of scutellum, first flagellum slightly broader than long, less than half as long as second flagellomere, flagellomeres 2–11 roughly twice as long as broad and their nearly equal to each other in length (Fig. 14); mandible tridentate, no inferior projection; characters of forewing and hindwing same as in female; fore and middle tibiae with one spine on outer surface, hind tibia without spine; tarsomeres 1–3 of the foreleg flattened and broadened, triangle-shaped, apical median deeply excavated, outer surface with golden fringes (Fig. 15), inner surface of tarsomeres 2–3 with black spot (Fig. 16); middle tibial spur present, middle tarsus somewhat broadened, outer surface with long plumose white hairs; hind basitarsus much less than half the length of hind tibia and narrower than the latter, outer surface with long plumose white hairs; claws with inner median tooth, arolia absent (Fig. 17); T2–T5 with strong postgradular grooves (Fig. 18); T6 bent to ventral surface, in dorsal view, apical margin of T6 with weakly emarginated medially, median concave and lateral region bulbous (Fig. 19); in ventral view, T6 with a carina, not toothed, the carina rounded medially and extending the apex of T6, apical region of carina bulbous except median, median concave and weakly emarginated (Fig. 20); metasoma only three sterna exposed (Fig. 21). Clypeus, mandible, vertex, frons, antenna, pronotal lobe, mesoscutum, scutellum black; except inner surface of fore tibia yellowish brown, fore tarsus brownish yellow, and middle tarsus yellowish brown, other parts of all legs black. Pubescence denser than that of female; lower part of clypeus, paraocular area, lower part of gena, pronotal lobe, mesepisternum, and posterolateral surface of propodeum with longer plumose white hairs; T3–T5 postgradular grooves covered with short plumose yellowish-brown hairs; disc of S1 covered with triangle-shaped plumose white hairs, S2 with apical band of plumose white hairs (Fig. 21); coxa, trochanter, femur of fore and middle leg, and hind coxa with plumose white hairs; genitalia as in Figs. 37, 38.

Type material. Holotype, Ƥ, China, Guangxi, Jingxi, Bangliang, 23.13ºN, 106.42ºE, 5 Aug. 2010, coll. Zeqing NIU. Allotype, 3, same label information as the holotype.

Distribution. China (Guangxi).

Floral association. Unknown.

Etymology. Named after the type locality, Guangxi province, China.