Lasioglossum (Hemihalictus) sexstrigatus (Schenck, 1869)

Murao, Ryuki, 2021, Redefinition of the sexstrigatus group of Lasioglossum (Hemihalictus) Cockerell, 1897 (Hymenoptera, Apoidea, Halictidae), with a revision of Japanese species, European Journal of Taxonomy 763, pp. 1-74 : 59-60

Key to species of the Lasioglossum (Hemihalictus) sexstrigatus group in Japan

Females

1. Metasoma generally reddish over entire surface ( Fig. 12A ) ............................................................... ....................................... Lasioglossum (Hemihalictus) sphecodicolor Sakagami & Tadauchi, 1995

– Metasoma generally black over entire surface .................................................................................. 2

2. Disc of T1 with lineolation (e.g., Fig. 15A–B ).................................................................................. 3

– Disc of T1 without lineolation (e.g., Fig. 15C )................................................................................ 12

3. Lineolation of T1 nearly over entire surface ( Fig. 15A, D–F ) .......................................................... 4

– Lineolation of T1 over part of surface ( Figs 15B , 16A–C, E )........................................................... 7

4. Ridges of metapostnotum short, reaching anterior half ( Fig. 9F ) (distribution: northern to central Ryukyus)......................................................................... L. (H.) smilodon Ebmer & Sakagami, 1994

– Ridges of metapostnotum long, reaching posterior margin ( Figs 4F , 7F , 8F ) ................................... 5

5. IS of mesoscutum nearly smooth on posterior margin; T1 with silky dull luster................................ .......................................................................................... L. (H.) ohei Hirashima & Sakagami, 1966

– IS of mesoscutum with distinct tessellation over entire surface; T1 with enamel-like luster ........... 6

6. Head longer than wide or slightly longer than wide (HL/HW ratio= 1.02–1.07, n =5) (restricted to coastal sand dunes) ......................................................... L. (H.) frigidum Sakagami & Ebmer, 1996

– Head wider than long or nearly as long as wide (HL/ HW raito= 0.94–1.0, n =5) (distribution: Izushotô Islands) .............................................................................. L. (H.) simplicior ( Cockerell, 1931)

7. Ridges of metapostnotum short, reaching anterior half ( Fig. 5F ) (distribution: Ryukyus) ............... 8

– Ridges of metapostnotum long, reaching posterior margin or anterior ⅔ ( Figs 10F , 11E , 13E )..... 10

8. Disc of T1 with sparse short hairs ( Murao 2012: fig. 7)....... L. (H.) tadauchii Murao, 2012 (in part)

– Disc of T1 withtout distinct hairs ( Fig. 15B )..................................................................................... 9

9. Disc of T1 with very weak lineolation on only basally ....................................................................... ...................................................................... L. (H.) amamiense Ebmer & Sakagami, 1994 (in part)

– Disc of T1 with very weak lineolation interrupted on medial area ( Fig. 15B ).................................... ......................................................................................................... L. (H.) ikudomei Murao sp. nov.

10. IS of mesoscutum medially to posteriorly smooth ( Fig. 11D )............................................................. ................................................................................................. L. (H.) speculinum ( Cockerell, 1925)

– IS of mesoscutum medially to posteriorly tessellate ( Figs 10E , 13D ) .............................................11

11. Metapostnotum dimly shiny, with distinct tessellation among ridges ( Fig. 10F )................................ ..................................................................................................................... L. (H.) spectrum sp. nov.

– Metapostnotum shinier, without distinct tessellation among ridges ( Fig. 13E ) .................................. .............................................................................................................. L. (H.) subsimplicior sp. nov.

12. Disc of T1 with distinct hairs and PP ( Fig. 15C )............................................................................. 13

– Disc of T1 without hairs and PP ( Fig. 16F )..................................................................................... 14

13. IS of mesoscutum medially to posteriorly nearly smooth ( Fig. 6D ) ................................................... ................................................................................................ L. (H.) kiautschouense ( Strand, 1910)

– IS of mesoscutum medially to posteriorly distinctly tessellate ( Murao 2012: fig. 3) (distribution: central Ryukyus) ................................................................... L. (H.) tadauchii Murao, 2012 (in part)

14. Distal process of labrum with horn-like lateral projection ( Fig. 14D ) ................................................ .................................................................................................... L. (H.) taeniolellum ( Vachal, 1903)

– Distal process of labrum without lateral projection (e.g., Fig. 4D ) ................................................. 15

15. Ridges of metapostnotum short, reaching anterior half ( Murao et al. 2010: fig. 1N) (distribution: central Ryukyus) ........................................... L. (H.) amamiense Ebmer & Sakagami, 1994 (in part)

– Ridges of metapostnotum long, reaching posterior margin................................................. L. (H.) sp.

Males

1. Metasoma generally reddish over entire surface as in female ( Fig. 12A )........................................... ....................................... Lasioglossum (Hemihalictus) sphecodicolor Sakagami & Tadauchi, 1995

– Metasoma generally black over entire surface .................................................................................. 2

2. Clypeus nearly black, without distinct yellow spot on lower half ( Figs 5C , 9C ).............................. 3

– Clypeus with a distinct yellow spot on lower half ( Figs 4C , 7C , 8C , 10C , 14C ).............................. 4

3. F2 long, over 1.5× F1.................................................................................. L. (H.) ikudomei sp. nov.

– F2 short, under 1.5× F1....................................................... L. (H.) amamiense Ebmer & Sakagami, 1994 and L. (H.) smilodon Ebmer & Sakagami, 1994 (species with allopatric distributions)

4. F2 long, over 1.5× F1........................................................................................................................ 5

– F2 short, approximately or under 1.5× F1......................................................................................... 6

5. Head wider than long, HL/ HW ratio 0.90–0.96......................... L. (H.) taeniolellum ( Vachal, 1903)

– Head longer than wide, HL/ HW ratio 1.04–1.07 (restricted to coastal sand dunes) .......................... ........................................................................................ L. (H.) frigidum Sakagami & Ebmer, 1996

6. F2 nearly as long as F1; labrum without basal elevation..................................................................... .......................................................................................... L. (H.) ohei Hirashima & Sakagami, 1966

– F2 1.4–1.5 × F1; labrum with a distinct basal elevation ( Fig. 2B ) ...................................................... ............................... L. (H.) simplicior ( Cockerell, 1931) , L. (H.) spectrum sp. nov., and L. (H.) sp.

Figures

Fig. 12. Lasioglossum (Hemihalictus) sphecodicolor Sakagami & Tadauchi, 1995. A. ♀, dorsal habitus. B. ♀, head in frontal view. C. ♂, head in frontal view. D. ♀, labrum. E. ♀, mesoscutum. F. ♀, metapostnotum. Scale bars: A = 3 mm; B–C = 1 mm; D = 0.2 mm; E–F = 0.5 mm.

Fig. 15. 1st metasomal tergum, ♀. A. Lasioglossum (Hemihalictus) frigidum Sakagami & Ebmer, 1996. B. L. (H.) ikudomei sp. nov. C. L. (H.) kiautschouense (Strand, 1910). D. L. (H.) ohei Hirashima & Sakagami, 1966. E. L. (H.) simplicior (Cockerell, 1931). F. L. (H.) smilodon Ebmer & Sakagami, 1994. Scale bars: 1 mm.

Fig. 16. 1st metasomal tergum, ♀. A–B. Lasioglossum (Hemihalictus) spectrum sp. nov. C. L. (H.) speculinum (Cockerell, 1925). D. L. (H.) sphecodicolor Sakagami & Tadauchi, 1995. E. L. (H.) subsimplicior sp. nov. F. L. (H.) taeniolellum (Vachal, 1903). Scale bars: 1 mm.

Fig. 9. Lasioglossum (Hemihalictus) smilodon Ebmer & Sakagami, 1994. A. ♀, lateral habitus. B. ♀, head in frontal view. C. ♂, head in frontal view. D. ♀, labrum. E. ♀, mesoscutum. F. ♀, metapostnotum. Scale bars: A = 2 mm; B = 1 mm; C, E–F = 0.5 mm; D = 0.2 mm.

Fig. 4. Lasioglossum (Hemihalictus) frigidum Sakagami & Ebmer, 1996. A. ♀, lateral habitus. B. ♀, head in frontal view. C. ♂, head in frontal view. D. ♀, labrum. E. ♀, mesoscutum. F. ♀, metapostnotum. Scale bars: A = 2 mm; B, E–F = 0.5 mm; C–D = 0.2 mm.

Fig. 7. Lasioglossum (Hemihalictus) ohei Hirashima & Sakagami, 1966. A. ♀, lateral habitus. B. ♀, head in frontal view. C. ♂, head in frontal view. D. ♀, labrum. E. ♀, mesoscutum. F. ♀, metapostnotum. Scale bars: A = 2 mm; B = 1 mm; C, E–F = 0.5 mm; D = 0.2 mm.

Fig. 8. Lasioglossum (Hemihalictus) simplicior (Cockerell, 1931). A. ♀, lateral habitus. B. ♀, head in frontal view. C. ♂, head in frontal view. D. ♀, labrum. E. ♀, mesoscutum. F. ♀, metapostnotum. Scale bars: A = 3 mm; B–C = 1 mm; D = 0.25 mm; E–F = 0.5 mm.

Fig. 5. Lasioglossum (Hemihalictus) ikudomei sp. nov. A. ♀, lateral habitus. B. ♀, head in frontal view. C. ♂, head in frontal view. D. ♀, labrum. E. ♀, mesoscutum. F. ♀, metapostnotum. Scale bars: A = 2 mm; B–C, E = 1 mm; D = 0.2 mm; F = 0.5 mm.

Fig. 10. Lasioglossum (Hemihalictus) spectrum sp. nov. A. ♀, lateral habitus. B. ♀, head in frontal view. C. ♂, head in frontal view. D. ♀, labrum. E. ♀, mesoscutum. F. ♀, metapostnotum. Scale bars: A = 3 mm; B = 1 mm; C, E–F = 0.5 mm; D = 0.2 mm.

Fig. 11. Lasioglossum (Hemihalictus) speculinum (Cockerell, 1925), ♀. A. Lateral habitus. B. Head in frontal view. C. Labrum. D. Mesoscutum. E. Metapostnotum. Scale bars: A = 3 mm; B, D–E, = 0.5 mm; C = 0.2 mm.

Fig. 13. Lasioglossum (Hemihalictus) subsimplicior sp. nov., ♀. A. Lateral habitus. B. Head in frontal view. C. Labrum. D. Mesoscutum. E. Metapostnotum. Scale bars: A = 3 mm; B = 1 mm; C = 0.25 mm; D–E = 0.5 mm.

Fig. 6. Lasioglossum (Hemihalictus) kiautschouense (Strand, 1910), ♀. A. Lateral habitus. B. Head in frontal view. C. Labrum. D. Mesoscutum. E. Metapostnotum. Scale bars: A = 3 mm; B, D–E = 0.5 mm; C = 0.25 mm.

Fig. 14. Lasioglossum (Hemihalictus) taeniolellum (Vachal, 1903). A. ♀, lateral habitus. B. ♀, head in frontal view. C. ♂, head in frontal view. D. ♀, labrum. E. ♀, mesoscutum. F. ♀, metapostnotum. Scale bars: A = 3 mm; B–C, E–F = 0.5 mm; D = 0.25 mm.

Fig. 2. A, E. Lasioglossum (Hemihalictus) sexstrigatus (Schenck, 1869). A. ♂, lateral habitus. E. ♀, mesepisternum. — B. L. (H.) taeniolellum (Vachal, 1903), ♂, labrum. — C, F. L. (H.) frigidum Sakagami & Ebmer, 1996. C. ♂, cephalic polymorphism. F. ♀, metasomal terga. — D. L. (H.) simplicior (Cockerell, 1931), ♂, cephalic polymorphism. Scale bars: A = 2 mm; B = 0.2 mm; C, E = 0.5 mm; D, F = 1 mm.