Lasioglossum (Evylaeus) silvicolum 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 : 18-19

Lasioglossum (Evylaeus) silvicolum Murao sp. nov.

( Figs. 4 C, 4D, 10)

Description. Female. Body length 4.8–5.4 mm, wing length 4.3–4.7 mm (n= 10).

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

Pilosity. T1 ( Fig. 4 D) medially with dense simple and short hairs. Basal hair bands slightly present on T2, but sometimes indistinct. Apical fimbriae on metasomal terga absent.

Structure. Head wider than long; head length/width ratio 0.93–0.98 (n= 10). Interocellar distance subequal to ocellocular distance. Frons and paraocular area dull, reticulate-punctate. Supraclypeal area ( Fig. 10 B) enamel-like luster, and with moderately dense PP; IS smooth. Clypeal length 1.2x between lower rim of antennal socket and upper margin of clypeus; enamel-like luster, with sparse PP on upper half, and with sparse larger shallow PP on lower half; IS smooth on the entire surface. Basal area of labrum 2.4x as wide as long; distal process slender, without lateral projection; keel of distal process moderately broad, apically bluntly pointed in frontal view. Scape length 0.5–0.6 mm (n= 5). Mesoscutum ( Fig. 10 C, D) dull, with dense PP and IS with distinct tessellation on the entire surface. Mesoscutellum ( Fig. 10 E) shiny, marginally and medially with moderately dense PP; IS smooth on the entire surface. Mesepisternum ( Fig. 10 F) shiny, with sparse PP on upper area, and with reticulate PP on lower area; IS smooth on upper area. Propodeal dorsum ( Fig. 10 H) 0.8x mesoscutellum, and nearly as long as metanotum, with longitudinal ridges on the entire surface; dorsomedial ridges long, but not attaining to apical margin that nearly smooth or weak tessellation; propodeal side weakly rugulose, with distinct tessellation; lateral slope and shield with weak tessellation. Inner hind tibial spur ( Fig. 10 I) with 4–5 teeth (n= 8). T1 ( Fig. 4 D) basally with very weak lineolation (but one paratype without lineolation), and medially with dense fine PP. T2 basally and medially without lineolation, apically with weak transverse lineolation. T3–T4 with weak transverse lineolation on the entire surface.

Male. Unknown.

Remarks. The species code sp. Y–2 reported by Maeta et al. (2004) corresponds to this new species. Within the sexstrigatum -group, this species is similar to Lasioglossum (Evylaeus) bicornutum sp. nov. and L. (E.) zipangu Ebmer & Sakagami from the southern Ryukyus. For the differences among the species, see the key. So far as the first author surveyed in Iriomote-jima, this species was found only in or around the humid subtropical forest.

Etymology. The specific name is derived from the habitat of this species at type locality.

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

Flight records. Female: March to November.

Flower records. The flowering plants visited by this species were four species in four families listed as follows. Apiaceae : Oenanthe javanica var. japonica . Melastomataceae : Melastoma candidum . Rubiaceae : Ophiorrhiza kuroiwae . Rutaceae : Zanthoxylum ailanthoides var. ailanthoides .

Type material. Holotype (Type No. ELKU 3308): female, Mt. Omoto-dake, Ishigaki-jima, Okinawa Pref., Ryukyus, JAPAN, 16. iii. 1964 (Y. Miyatake leg., ELKU). Paratypes: [Ryukyus: JAPAN] Ishigaki-jima, Okinawa Pref.: 4 females, same locality as the holotype, 16. iii. 1964 (H. Makihara, ELKU), 16. iii. 1964 (T.Shirôzu, ELKU). Iriomote-jima, Okinawa Pref.: 3 females, 11–12. iii. 1964 (M. Yoshimoto & J. Harrell, ELKU), 23–27. vi. 2007 (Y. Maeta, MCDS), 14–18. ix. 2003 (Y. Maeta, MCDS); 1 female, Marantu, 26. v. 2003 (M. Hannan, MCDS); 1 female, Ôtomi-rindô, 16. iii. 2005 (R. Murao, RMPC); 2 females, Shirahamarindô, 18. v. 2007 (R. Murao, RMPC), 21. v. 2007 (R. Murao, RMPC); 1 female, Ushiku-mori, alt. 250m, 3–4. xi. 1963 (G. A. Samuelson, ELKU).

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

Figures

FIGURE 10. Lasioglossum (Evylaeus) silvicolum 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.