Lasioglossum (Evylaeus) bicornutum Murao

Murao, Ryuki, Tadauchi, Osamu, Goubara, Masashi & Maeta, Yasuo, 2010, Taxonomy of the carinaless group of Lasioglossum (Evylaeus) (Hymenoptera, Halictidae) from the Ryukyu Islands, Japan, with description of seven new species, Zootaxa 2669, pp. 1-33 : 7-9

Lasioglossum (Evylaeus) bicornutum Murao sp. nov.

( Figs. 3 , 4A, 4B )

Description. Female. Body length 5.4–6.6 mm, wing length 4.8–5.7 mm (n= 5).

Color. Tegula yellowish brown or brown translucent. Posterior margins of metasomal terga narrowly yellowish brown translucent.

Pilosity. T1 ( Fig. 4B ) medially with moderately dense simple and short hairs. Metasomal terga with neither basal hair bands nor apical fimbriae.

Structure. Head wider than or nearly as wide as long; head length/width ratio 0.95–1.01 (n= 10). Interocellar distance subequal to ocellocular distance. Frons and paraocular area dull, reticulate-punctate.

Supraclypeal area ( Fig. 3 B) dull, with sparse PP; IS with weak tessellation. Clypeal length 1.2x between lower rim of antennal socket and upper margin of clypeus, with moderately dense PP on upper half, and with larger shallow PP on lower half; IS with weak tessellation on upper half, and smooth on lower half. Basal area of labrum 3.1x as wide as long; lateral projections of distal process small, horn-like; keel of distal process moderately broad, apically bluntly pointed in frontal view. Scape length 0.6–0.8 mm (n= 5). Mesoscutum ( Fig. 3 C, D) shiny, with dense PP and IS with weak tessellation on the entire surface. Mesoscutellal IS marginally with weak tessellation, medially smooth; other sculptures similar to mesoscutum. Mesepisternum ( Fig. 3 F) shiny, nearly smooth on upper area, and with weak rugulae on lower area. Propodeal dorsum ( Fig. 3 H) 0.8x mesoscutellum, and 1.4x as long as metanotum; dorsomedially with longitudinal ridges on basal half, and with distinct tessellation on apical half; lateral slope, propodeal side, and shield with distinct tessellation on the entire surface. Inner hind tibial spur ( Fig. 3 I) with 3–4 teeth (n= 5). T1 ( Fig. 4B ) with weak lineolation on the entire surface, and medially with moderately dense fine PP. T2–T4 with weak lineolation on the entire surface.

Male. Unknown.

Remarks. The species code sp. Y–3 reported by Maeta et al. (2010) corresponds to this new species. Within the sexstrigatum -group, this species is similar to Lasioglossum (Evylaeus) silvicolum sp. nov. and L. (E.) zipangu Ebmer & Sakagami from the southern Ryukyus. For the differences among the species, see the key.

Etymology. The specific name is derived from the female labrum with horn-like lateral projections on the distal process.

Distribution. Japan (southern Ryukyus: Ishigaki-jima, Iriomote-jima).

Flight records. Female: March to October.

Flower records. The flowering plants visited by this species were five species in five families listed as follows. Asteraceae : Bidens pilosa var. minor . Fabaceae : Melilotus officinalis subsp. s uaveolens. Melastomataceae : Melastoma candidum . Primulaceae : Lysimachia sikokiana . Rubiaceae : Ophiorrhiza kuroiwae .

Type material. Holotype (Type No. ELKU 3305): female, Mt. Kawara-dake, Ishigaki-jima, Okinawa Pref., Ryukyus, JAPAN, 18. iii. 1964 (Y. Miyatake leg., ELKU). Paratypes: [Ryukyus: JAPAN] Ishigaki-jima, Okinawa Pref.: 1 female, same locality as the holotype, 28. x. 1963 (Y. Hirashima, ELKU); 1 female, Mt. Omoto-dake, 9. iv. 1979 (H. Makihara, ELKU). Iriomote-jima, Okinawa Pref.: 3 females, 7–11. vi. 2004 (Y. Maeta, MCDS), 23. v. 2007 (Y. Maeta, MCDS), 23–27. v. 2007 (Y. Maeta, MCDS); 1 female, Itokawa-rindô, 10–13. v. 2004 (T. Mita, RMPC); 1 female, Ôtomi, 16. iii. 2005 (R. Murao, RMPC); 2 females, Shirahama, Shirine, 23–27. iv. 2004 (T. Mita, RMPC); 2 females, Shirahama-rindô, 25. iv. 2004 (T. Mita, RMPC), 21. v. 2007 (R. Murao, RMPC); 1 female, Sonai, 15. iii. 2005 (R. Murao, RMPC); 1 female, Uehara, 25. v. 1975 (H. Makihara, ELKU).

Type depository. The holotype and 10 paratypes are deposited in ELKU, and three paratypes in MCDS.

Figures

FIGURE 3. Lasioglossum (Evylaeus) bicornutum Murao, sp. nov. A – F: holotype, female. G – I: paratype, female. A: lateral habitus. B: lower face. C: mesoscutum. D: sculpture on mesoscutum. E: mesoscutellum. F: mesepisternum. G: labrum. H: propodeal dorsum. I: inner hind tibial spur. Scale bars: H, 0.25 mm; G, I, 0.2 mm.

FIGURE 4. A, B: Lasioglossum (Evylaeus) bicornutum Murao, sp. nov. C, D: Lasioglossum (Evylaeus) silvicolum Murao, sp. nov. E, F: Lasioglossum (Evylaeus) latifacies Murao, sp. nov. A – F: holotypes, females. A, C, E: head in frontal view. B, D, F: first metasomal tergum (left half, sculpture; right half, hair pattern). Scale bar: 1 mm.