Redefinition of the sexstrigatus group of Lasioglossum (Hemihalictus) Cockerell, 1897 (Hymenoptera, Apoidea, Halictidae), with a revision of Japanese species Author Murao, Ryuki 7E665839-6675-4365-A7EA-169D4E4DA008 Regional Environmental Planning Co., Ltd, 1 - 10 - 12, Muromi, Sawara-ku, Fukuoka, 814 – 0015 Japan. r.murao@mbr.nifty.com text European Journal of Taxonomy 2021 2021-08-18 763 1 74 http://dx.doi.org/10.5852/ejt.2021.763.1463 journal article 4854 10.5852/ejt.2021.763.1463 31f73be9-4a90-4c0a-937e-784437eff4bd 2118-9773 5235968 9823AAD7-1113-434B-9882-1CF885DE7CED 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.