Lasioglossum (Evylaeus) amamiense Ebmer & Sakagami, 1994

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 : 3-6

Lasioglossum (Evylaeus) amamiense Ebmer & Sakagami, 1994

( Figs. 1 , 2 , 17A–D )

Lasioglossum (Evylaeus) amamiense Ebmer & Sakagami, 1994 , Bull. Fac. Agr. Shimane Univ., 28: 32 [female, Japan: Amami-Ôshima, Kagoshima Pref.]; Tadauchi et al., 1998, Nat. Hist. Bull. Ibaraki Univ., 2: 232; Ikudome, 1999, Ident. Guide Aculeata Nansei Is., Jap.: 584.

Redescription (male: previously unknown). Female. Body length 4.8–6.1 mm, wing length 3.8–5.0 mm (n= 10).

Color. Tegula yellowish brown, translucent. Posterior margins of metasomal terga broadly yellowish brown, translucent.

Pilosity. T1 ( Fig. 2 C) disc bare. T2–T3 with small basal hair bands. T2–T4 with apical fimbriae.

Structure. Head wider than or as wide as long; head length/width ratio 0.91–1.0 (n= 58). Interocellar distance 1.2x ocellocular distance. Frons dull, reticulate-punctate. Paraocular area with dense PP, upper and middle dull, lower shiny. Supraclypeal area ( Fig. 1 B) dull, with moderately dense PP; IS with distinct tessellation. Clypeal length 1.2x distance between lower rim of antennal socket and upper margin of clypeus; shiny, with shallow PP on the entire surface; IS of upper 1/3 with weak tessellation, and lower 2/3 smooth. Basal area of labrum 2.1x as wide as long; distal process acuminate, without lateral projection; keel of distal process broad, apically pointed in frontal view. Scape length 0.6–0.7 mm (n= 10). Mesoscutum ( Fig. 1 C, D) dull, with dense PP on the entire surface; IS anteriorly and medially with distinct tessellation, posteriorly with weak tessellation or smooth. Mesoscutellum ( Fig. 1 E) similar to mesoscutum. Mesepisternum ( Fig. 1 F) shiny, with moderately dense shallow PP on upper area, and with weak rugulae on lower area; IS nearly smooth on upper area. Propodeal dorsum ( Fig. 1 N) 0.7x mesoscutellum, and 1.3x as long as metanotum, dorsomedially with irregular sinuate ridges on basal half, and with weak tessellation on apical half; dorsolaterally with longitudinal ridges; propodeal side weakly rugulose, with distinct tessellation; shield with distinct tessellation. Inner hind tibial spur ( Fig. 1 O) with 3–4 teeth (n= 20). T1 ( Fig. 2 C) almost entirely smooth. T2 basally with very weak lineolation, medially and posteriorly without lineolation. T3–T4 similar lineolation with T2 on the entire surface.

Male. As in female except as follows. Body length 4.3–5.3 mm, wing length 3.6–4.9 mm (n= 9).

Color. Lower half of clypeus slightly dark yellow; labrum yellow or brown; pedicel and F1–F2 yellowish brown ventrally; junction between femur and tibia sometimes slightly yellowish brown (generally, legs nearly black or brown).

Pilosity. T1 ( Fig. 2 D) medially with sparse short hairs. T2–T5 similar hairs with T1 on the entire surface, sparse. Metasomal terga with neither basal hair bands nor apical fimbriae. S3–S5 ( Fig. 2 B) posterior margins with fine branched hairs, moderately dense and short.

Structure. Head shape variable, usually slightly wider than, or as wide as long; head length/width ratio 0.95–1.04 (n= 12). Interocellar distance 1.2x ocellocular distance. Clypeal length 1.5x distance between lower rim of antennal socket and upper margin of clypeus. Clypeus with sparse shallow PP and IS smooth on the entire surface. Basal area of labrum 3x as wide as long. Scape length 0.38–0.52 mm (n= 12), F2 1.3x F1. Mesoscutal IS anteriorly with weak tessellation, medially and posteriorly smooth. Mesoscutellum ( Fig. 1 K) with sparse PP, IS smooth. Mesepisternum with moderately dense PP and IS smooth on lower area. Propodeum dorsomedially with short longitudinal ridges on basal half, and with weak tessellation on apical half. T1 ( Fig. 2 D) nearly smooth on the entire surface. T2–T3 basally and medially without lineolation, apically with very weak transverse lineolation. Median process of S7–S8 ( Fig. 2 H) rounded apically, short in S7, moderately long in S8. Genitalia as in Fig. 2 E–G. Gonobasal ventral arm ring-shaped, with apical ends appearing connected to each other; bottom slightly depressed. Gonocoxite smooth. Gonostylus rounded apically in lateral view, with sparse short hairs. Retrorse lobe ( Fig. 2 G) moderately long, rounded apically, with moderately dense short hairs on its surface.

Variation. In female, T1 generally smooth, but some specimens basally with very weak lineolation. In male, T2 generally only apically with very weak lineolation, but some specimens without lineolation on the entire surface. In addition, the cephalic polymorphism occurs in male as shown in Fig. 17A–D . The small males are accompanied with small process on genal area ( Fig. 17C ), on the other hand, the larger males with gigantic head and large genal process ( Fig. 17D ). In the several species belonging to sexstrigatum -group, such male polymorphism has been known to be caused by the allometric development as detailed shown in Lasioglossum (Evylaeus) ohei Hirashima & Sakagami (Sakagami et al. 1966) .

Remarks. Within the sexstrigatum -group, this species is closely similar to Lasioglossum (Evylaeus) taeniolellum (Vachal) from Japan proper, in having the head broad in both sexes, the female metasomal terga with distinct apical fimbriae, and the female T1 nearly smooth. But it is separated from L. (E.) taeniolellum by the following morphological characters: female labrum without lateral projection on distal process, female mesepisternum with shallow PP on upper area, male F2 1.3x F1, and gonostylus rounded apically in lateral view. In contrast, in L. (E.) taeniolellum , female labrum with horn-like lateral projections on distal process, female mesepisternum with deep PP on upper area, male F2 twice the length of F1, and gonostylus narrow apically in lateral view. So far as the first author surveyed in both Amami-Ôshima and Kikai-jima, this species was mainly collected from open land such as cultivated or urban areas at lowland and seaside wasteland. It was not collected from the mountain areas.

Distribution. Japan (central Ryukyus: Amami-Ôshima, Kikai-jima, Tokuno-shima).

Flight records. Female: March to October. Male: May to September.

Flower records. The flowering plants visited by this species were 13 species in nine families listed as follows. Asteraceae : Aster sp.; Bidens pilosa var. minor ; Ixeris stolonifera ; Ix. sp.; Youngia japonica . Brassicaceae : Brassica rapa var. oleifera . Caprifoliaceae : Sambucus chinensis . Crassulaceae : Sedum sp. Goodeniaceae : Scaevola taccada . Oxalidaceae : Oxalis corniculata . Plumbaginaceae : Limonium wrightii var. arbusculum . Rosaceae : Rhaphiolepis indica var. umbellata . Rubiaceae : Paederia scandens .

Specimens examined. Holotype: female, Shin-mura, Nishinakama, Amami-Ôshima, Kagoshima Pref., Ryukyus, JAPAN, 12. iv. 1970 (S. F. Sakagami & H. Fukuda, ELKU). Paratypes: [Ryukyus: JAPAN] Amami- Ôshima, Kagoshima Pref.: 6 females, Naze, 9. iv. 1970 (S. F. Sakagami & H. Fukuda, SCMH); 5 females, same locality as the holotype, 10–12. iv. 1970 (S. F. Sakagami & H. Fukuda, SCMH), 3. x. 1971 (H. Fukuda, SCMH). Kikai-jima, Kagoshima Pref.: 1 female, 3–6. x. 1985 (M. Tatsuno, SCMH). Other material: Amami- Ôshima, Kagoshima Pref.: 1 female, same data as the holotype; 22 females and 2 males, same locality as the holotype, 16. v. 1953 (T. Shiraki, ELKU), 22. v. 1954 (S. Taniguchi, ELKU), 20. vii. 1954 (S. Hisamatsu, ELKU), 23. vii. 1954 (S. Miyamoto, Y. Hirashima & S. Ueda, ELKU), 4–5. iv. 1956 (S. Miyamoto, ELKU), 2. iv. 1958 (M. Takahashi, ELKU), 12. iv. 1970 (S. F. Sakagami & H. Fukuda, SCMH); 1 female, 23. iii. 1973 (O. Tadauchi, ELKU); 6 females, 11. iii., 26. iii. 1958 (M. Takahashi, ELKU); 2 females and 1 male, Ayamarumisaki, Kasari-cho, 13. vii. 2005 (R. Murao, RMPC); 2 females, Kasarizaki, Kasari-cho, 13. vii. 2005 (R. Murao, RMPC); 1 male, Kasari, Kasari-cho, 7. vii. 1981 (Y. Haneda, SCMH); 5 females and 2 males, Naze, 27. vii. 1954 (S. Miyamoto & Y. Hirashima, ELKU), 9. iv. 1970 (S. F. Sakagami & H. Fukuda, SCMH); 1 female, Oshuku, 26. iii. 1973 (O. Tadauchi, ELKU); 2 females, Yamama, Sumiyou-son, 27. iii. 2003 (R. Murao, RMPC); 1 female, Yamato-son, 5. iv. 2005 (K. Mitai, RMPC); 3 males, Sinokawa, 21. v. 1954 (S. Taniguchi, ELKU); 1 male, Yadori-hama, Setouchi-cho, 12. vii. 2005 (R. Murao, RMPC). Kikaijima, Kagoshima Pref.: 4 females, Hyakunodai, 20. ix. 2006 (R. Murao, RMPC); 1 female and 2 males, Tonbizaki, 20. ix. 2006 (R. Murao, RMPC); 1 female, Nakama, 20m, 19. x. 1987 (S. Ikudome, SCMH).

Figures

FIGURE 1. Lasioglossum (Evylaeus) amamiense Ebmer & Sakagami. A – F: holotype, female. M – O: female. G – L, P, Q: male. A, G: lateral habitus. B, H: lower face. C, I: mesoscutum. D, J: sculpture on mesoscutum. E, K: mesoscutellum. F, L: mesepisternum. M, P: labrum. N, Q: propodeal dorsum. O: inner hind tibial spur. Scale bars: N, 0.5 mm; Q, 0.25 mm; M, O, P: 0.2 mm.

FIGURE 2. Lasioglossum (Evylaeus) amamiense Ebmer & Sakagami. A, C: holotype, female. B, D, E – H: male. A: head in frontal view. B: metasomal sterna. C, D: first metasomal tergum (left half, sculpture; right half, hair pattern). E – G: male genitalia (E: left, ventral view; right, dorsal view. F: lateral view. G: retrorse lobe). H: seventh and eighth metasomal sterna. Scale bars: A, B, C, D, 1 mm; E, F, H, 0.2 mm; G, 0.1 mm.

FIGURE 17. A – D: Lasioglossum (Evylaeus) amamiense Ebmer & Sakagami, male. E – H: Lasioglossum (Evylaeus) canaliculatum Murao, sp. nov., male. A, B, E, F: head in frontal view (stippled area: yellow coloration). C, D, G, H: head in lateral view. A, C, E, G: normal head. B, D, F, H: gigantic head. Scale bar: 1 mm.