Synopsis of Lasioglossum (Dialictus) Robertson, 1902 (Hymenoptera, Apoidea, Halictidae) in Japan, the Korean Peninsula and Taiwan

Twelve species in total are recognized for the subgenus Lasioglossum (Dialictus) Robertson, 1902 from Japan, the Korean Peninsula and Taiwan. Lasioglossum (Dialictus) alishanense sp. nov. and L. (D.) taiwanense sp. nov. from Taiwan, are described as new. Four species are recorded from the following localities for the first time: L. (D.) miyabei Murao, ebmer & Tadauchi, 2006 from the Korean Peninsula (South Korea); L. (D.) ellipticeps (Blüthgen, 1923), L. (D.) virideglaucum ebmer & Sakagami, 1994 and L. (D.) viridellum (cockerell, 1931) from South Korea. Lasioglossum (Dialictus) atroglaucum (Strand, 1913) is redescribed, L. (D.) ellipticeps, L. (D.) problematicum (Blüthgen, 1923), L. (D.) virideglaucum, and L. (D.) viridellum are supplementary described. a key to species is provided. Bionomical data, such as flight and flower records or habitat, are reported for some species. The distributions of all species are mapped. dNa barcodes of L. (D.) miyabei, L. (D.) pseudannulipes (Blüthgen, 1925), and L. (D.) virideglaucum are provided.

Each series is monophyletic as supported by phylogenetic analyses based on molecular data (Danforth et al. 2003;Gibbs et al. 2012).However, there is no agreement among taxonomists with regard to the number and extent of the subgeneric classifi cation of Lasioglossum and it is not necessarily applied when classifying the male.The Palaearctic subgenera Acanthalictus, Evylaeus, Dialictus, Hemihalictus and Sphecodogastra of the Hemihalictus series, e.g., have been treated as L. (Evylaeus) (e.g., Ebmer 2002;Murao & Tadauchi 2007;Pesenko 2007a, as the genus Evylaeus).Recent phylogenetic studies (Danforth 1999;Danforth et al. 2003;Gibbs et al. 2012Gibbs et al. , 2013) ) based on molecular data, however, do not recognize L. (Evylaeus), used by most Palaearctic researchers, as a monophyletic group.They will probably shed light on our understanding of the relationships among taxa, evolutionary patterns of sociality and the strict delimitation of genera and subgenera.
However, the basic information on the Lasioglossum fauna in eastern Asia is still poor, particularly in the Oriental Region.
Dialictus Robertson, 1902 is one of the subgenera in Lasioglossum.This name has been applied to the majority of species with the metallic form, including the black one without complete lateral carina on the posterior surface of the propodeum (referred to as black Dialictus, acarinate, noncarinate or carinaless Evylaeus) in the Hemihalictus series (e.g., Michener 2000Michener , 2007)).On the other hand, Dialictus in the Palaearctic Region have been treated as the green Lasioglossum (Evylaeus) (Ebmer 2002;Pesenko 2007a).In the recent treatment of Lasioglossum, as outlined above, mostly metallic species in the Hemihalictus series are recognized as Dialictus (Gibbs et al. 2013).420 L. (Dialictus) species are listed in the world (Ascher & Pickering 2015, including Afrodialictus Pauly, 1984).Recently, L. (Dialictus) species from Canada and part of North America were revised by Gibbs (2010Gibbs ( , 2011)), who provided useful identifi cation keys and good photographs of many specimens, whereas for those of eastern Asia (Russian Far East and eastern Siberia) only an identifi cation key is available (Pesenko 2007b, as Evylaeus).
A further 10 species of Dialictus have been partially described or reported from Japan, the Korean Peninsula and/or Taiwan by various researchers (Japan: Ebmer & Sakagami 1990;Ebmer et al. 1994;Murao & Tadauchi 2008;Murao et al. 2006Murao et al. , 2009a;;Usui et al. 1976. Korean Peninsula: Ebmer 1978. Taiwan: Strand 1913).No revisional study has been conducted to date in these countries.In the course of a collaborative study of the Asian Lasioglossum fauna, we examined the L. (Dialictus) specimens collected from Japan, the Korean Peninsula and Taiwan.Through our examination, we recognized 12 L.
(Dialictus) species in total for these countries.Among them, two new species were found from Taiwan European Journal of Taxonomy 137: 1-50 (2015) and four known species were recorded from South Korea for the fi rst time.In this paper, two new species from Taiwan are described and the remainder are redescribed or additionally described, and drawings, photographs and scanning electron micrographs for diagnostically important characters are provided.DNA barcodes of some species and an illustrated key of all species are presented to facilitate species identifi cation in these countries.

Collection
This study is based on the specimens deposited in the following institutions and personal collections, which are referred to using the following abbreviations:

Terminology
Terminology and style used in the descriptions follow Murao et al. (2014).Abbreviations used in the text are as follows: Body measurements are given in ranges followed by the average and standard deviation.

Flower records
Records of fl owers visited by each species are based on specimen label data.The scientifi c names of fl owering plants visited by bees are cited from Yonekura & Kajita (2003-).

DNA barcoding
DNA extraction and PCR were conducted at the Kyushu University Museum (Fukuoka, Japan).DNA was extracted using a DNeasy Blood and Tissue Kit (Qiagen, Tokyo, Japan) following the manufacturer's instructions.A region of the cytochrome oxidase subunit I (COI) gene of mtDNA was amplifi ed using polymerase chain reaction (PCR) with the primers LCO1490 (5´-GGTCAACAAATCATAAAGATATTGG-3´) and HCO2198 (5´-TAAACTTCAGGGTGACCAAAAAATCA-3´) (Folmer et al. 1994).Each PCR mixture contained 2 μl of DNA template, 2.13 μl of 10× EX Taq Buffer (Takara bio), 0.75 μl of each primer (20 μM), 1.68 μl of dNTP (2.5 mM, Takara bio), and 0.25 μl of EX Taq DNA polymerase (Takara bio).MilliQ water was added to reach a total reaction volume of 20 μl.PCR conditions were as follows: 94 °C for 1 min, followed by 10 cycles of 94 °C for 1 min, 48 °C for 1 min 30 s, and 72 °C for 1 min 30 s, then 30 cycles at 94 °C for 1 min, 52 °C for 1 min 30 s, 72 °C for 1 min 30 s, and a fi nal 72 °C for 5 min.PCR products were run on a 1% agarose gel for 20 min, and then purifi ed with 2.6 μl of ExoSAP-IT (GE Healthcare Life Sciences).DNA sequencing was outsourced to the FASMAC Co., Ltd.(Kanagawa, Japan).The resulting sequences were aligned using the program MEGA (ver. 5;Tamura et al. 2011).The sequence data reported in the present paper are deposited at the DNA Data Base of Japan (DDBJ).

Diagnosis
This subgenus is usually separated from the other subgenera of Lasioglossum occurring in eastern Asia by having a combination of the head and mesosoma with brilliant or dull green-metallic luster in both sexes and the female fore wing with a weak second submarginal vein.In eastern Asia, the female of the European Journal of Taxonomy 137: 1-50 (2015) apristum group belonging to L. (Sphecodogastra) (corresponding to the carinate L. (Evylaeus) in the dissenting classifi cation (Ebmer 2002;Pesenko 2007a, as the genus Evylaeus)) has the same character states as L. (Dialictus).However, the members of this group can easily be separated from L. (Dialictus) in having the mesepisternum coarse reticulate-rugulose, the posterior surface of the propodeum with strong complete carina, and the inner hind tibial spur fi nely serrate.

Diagnosis
Species of the leucopus group may be strictly characterized by a combination of the following character states: 1) male F2 short, approximately 1.2-1.5 × as long as F1; 2) mesepisternum reticulate-punctate on lower area in both sexes (Fig. 1E); 3) male metasomal sterna not modifi ed (apical margin straight); 4) ventral retrorse lobe of male genitalia with moderately long setae only apically and distinct lineolation on surface (Fig. 2D, F-I).

Distribution
Palaearctic to northern Oriental Region.

Comments
This group is assumed to be monophyletic, based on the ventral retrorse lobe of male genitalia with moderately long setae only apically and the distinct lineolation on the surface.This character state may be unique within the subgenus.A comprehensive comparative study of the ventral retrorse lobe has not been performed for the subgenus, but this state may be an autapomorphy for the leucopus group.

Diagnosis
This species is similar to Lasioglossum angaricum (Cockerell, 1937) andL. viridellum (Cockerell, 1931) from eastern Asia in the leucopus group.It is separated from L. angaricum by the female T1 usually being without lineolation (sometimes T1 basally lineolate, but weaker than in L. angaricum) and the male sterna with sparse uniform hairs.In contrast, in L. angaricum the female T1 has distinct lineolation and the male S3-S5 is medially bare, laterally with tufts of long dense erect hairs (Pesenko 2007b).For the differences between females of this species and L. viridellum, see Key.

Flight records
Female: April to October.Male: June to October.

Flower records
Thirty-two species in 6 families were reported as fl oral hosts in Japan by Goubara et al. (2004).

Habitat
This species was collected from grassland in the Kumamoto Pref., Kyushu, western Japan.One of the collecting sites there is shown in Fig. 23B.

DNA barcodes
The COI gene sequences are deposited as DNA barcodes of L. (D.) pseudannulipes in the DDBJ under accession numbers LC027534 and LC027535.These numbers are also available in GenBank.

Diagnosis
This species is closely similar to Lasioglossum angaricum (Cockerell, 1937) and L. pseudannulipes (Blüthgen, 1925), as stated above.It is separated from L. angaricum by the disc of male sterna having sparse and uniform hairs.In contrast, in L. angaricum, the male S3-S5 are medially bare, laterally with tufts of long dense erect hairs (Pesenko 2007b).

Additional description
LABRUM (Fig. 1C-D).Basal area approximately 2.0 × as wide as long in female; basal elevation moderately developed in both sexes, depressed centrally in male; distal process of female slender, nearly as long as basal area, and without lateral projection, that of male absent; keel of distal process narrow, apically pointed; labral fi mbria acutely pointed at apex in both sexes.S7-S8 (Fig. 2E): S7 with moderately long, apex exceeding S8; S8 without median process.
MALE GENITALIA (Fig. 2A-D).Gonobase fl at at bottom, ventral arms connected with each other at upper ends; gonocoxite smooth, gently sloped in lateral view, inner and outer dorsal margins nearly parallel; gonostylus truncate apically in lateral view, located at top of gonocoxite, with sparse short hairs; ventral retrorse lobe long, reaching gonobase, with long and dense stetae apically (remaining parts with sparse short hairs) and distinct lineolation; penis valve higher than gonocoxite, without cleft on top.

Flight records
Female: April to September.
Male: July to September.

Flower records
In South Korea, it was collected on the fl owers of Potentilla hebiichigo Yonek.& H. Ohashi (Rosaceae) and Brassica sp.(Brassicaceae).

Comments
Male specimens from Primorsky and South Korea are studied in the present paper, including characters of the labrum and genitalia.Through this examination, we have concluded that the males of both this species and L. pseudannulipes cannot be clearly separated.A female specimen of this species examined in this study shows weak lineolation on T1 basally (female T1 basally usually with strong lineolation as in Fig. 25A).The character state of this female specimen overlaps with some female specimens European Journal of Taxonomy 137: 1-50 (2015) of L. pseudannulipes (see the description of Murao et al. 2009a).Lasioglossum viridellum and L. pseudannulipes could possibly represent the same species.It is diffi cult to resolve this, because we could not examine enough material of L. viridellum in this study.This problem needs to be addressed by including DNA analysis in a future study.

Diagnosis
This species is separated from related species by the combination of the following characters: female supraclypeus with sparse PP (IS = 1-4.7),male labrum without basal elevation, and male S4-S5 (particularly S5) laterally with hair tufts that are longer than the surrounding hairs.

Distribution
Japan (Hokkaido).This species has only been collected from Mt. Meakan-dake in the eastern part of Hokkaido.

Flight records
Both sexes: August.
In addition, this group can be classifi ed into two subgroups.The atroglaucum subgroup (L.atroglaucum, L. negoroi, L. taiwanense sp.nov., L. virideglaucum, and L. yamanei) is characterized by a combination of the male S5 with apical depression and without brush-like hairs (Fig. 5B, E, H, K, N), and the gonostylus of male genitalia without setae on the inner surface.The problematicum subgroup (L.alishanense sp.nov., L. problematicum, L. sanitarium, and L. sichuanense) is characterized by the male S5 with brushlike hairs along apical margin (Figs 13, 14B, E, H) and the gonostylus of male genitalia with dense short setae on the inner surface (Fig. 16D).The latter subgroup can be regarded as a monophyletic group by the characters of the male S5 and genitalia.These character states are unique in the subgenus and are considered to be autapomorphies.

Distribution
This group is distributed from the Far East to southern Asia.It is diverse in the northern Oriental Region.

Diagnosis
This species is easily separated from other members of the atroglaucum subgroup by the male S4 having dense and curly plumose hairs (Fig. 4A) and by the shape of the gonostylus (Fig. 7C).

Redescription Male
COLORATION.Body black except for the following parts: head dark green and mesosoma metallic green; clypeus yellow on lower half; mandible reddish brown apically; fl agellum blackish brown ventrally; tegula blackish brown translucent; tibial spur yellow; metasomal terga narrowly brown translucent apically.Wings transparent, veins and stigma brown.PUBESCENCE.Body hairs whitish, and covered with erect and sparse fi ne, branched hairs except for the following parts: lower paraocular area with sparse tomentose; lower clypeus with sparse simple hairs; tibial and tarsal hairs nearly simple; disc of metasomal terga with sparse and simple short hairs; disc of S2-S3 apically with moderately dense fi ne, branched hairs; disc of S4 apically with dense and curly plumose hairs (Fig. 4A); disc of S5 with sparse short and simple hairs, mixed with sparse fi ne, branched hairs laterally; disc of S6 with sparse short and simple hairs.European Journal of Taxonomy 137: 1-50 (2015) smooth, not carinate; lateral surface weakly rugulose; posterior surface with lateral carina on lower half, without oblique carina.Fore trochanter narrow, longer than wide.Hind tibia without basitibial plate.Hind basitarsus slender, approximately 4.6 × as long as wide.Inner hind tibial spur fi nely serrate.Fore wing with three submarginal cells.
GENITALIA (Fig. 7A-D).Gonobase fl at at bottom, ventral arms not connected with each other at upper ends; gonocoxite smooth, gently sloped in lateral view, inner dorsal margin angulate at the approximately basal half; gonostylus small and thin, bud-like in lateral view, located on top of gonocoxite, and with sparse short and a few relatively long hairs; ventral retrorse lobe tongue-like, moderately long but not reaching gonobase, with dense short setae; penis valve higher than gonocoxite, with low cleft on top.

Female
Unknown.

Distribution
Taiwan.

Flight period
Male: late June to early August.

Diagnosis
This species is separated from the other members of the atroglaucum subgroup by a combination of the following characters: disc of male S4 with short and moderately dense hairs (Fig. 4B); male S6 with a pair of thin hair tufts (Fig. 4B); and the gonostylus of male genitalia nearly rounded on top (Fig. 9C).

Additional description
LABRUM (Fig. 8C-D).Basal area approximately 2.6 × as wide as long in female, 3 × in male; basal elevation of female moderately developed, that of male absent; distal process of female slender, nearly as long as basal area, and without lateral projection, that of male absent; keel of distal process narrow, apically pointed in female; labral fi mbria acutely pointed at apex in both sexes.
STERNA.S4 and S6 normal shaped, not modifi ed.S7-S8 (Fig. 9E): S7 with long, apically rounded median process, apex exceeding S8; S8 without median process.MALE GENITALIA (Fig. 9A-D).Gonobase nearly fl at at bottom, ventral arms connected with each other at upper ends; gonocoxite smooth, gently sloped in lateral view, and inner dorsal margin angulate at approximately basal 1/3; gonostylus large, located at top of gonocoxite, with sparse short and moderately long hairs; ventral retrorse lobe moderately long but not reaching gonobase, with moderately dense short setae ventrally; penis valve higher than gonocoxite, with low cleft on top.

Distribution
Russian Far East (Primorsky, Khabrovsk), the Korean Peninsula (new record), Japan (Honshu, Shikoku, Kyushu, Yaku Is.),China (Sichuan, Shanxi, Yunnan Provs.).While conducting our study, the male of this species was found from several localities in South Korea (the female cannot be clearly separated from that of some related species such as L. problematicum).On the Korean Peninsula, Lasioglossum problematicum has been recorded from North Korea based on female specimens (Ebmer 1978).Pesenko (2007b) regarded the continental records of L. problematicum as L. virideglaucum.Our results support Pesenko's opinion.It might be prudent to remove L. problematicum from the Korean fauna.

Flight period
Female: April to September in Kyushu, Japan.Male: August to October.
The fl ight record of the female is based on specimens collected from Kyushu, Japan, because one of the related species, L. problematicum, does not sympatrically inhabit this area.

Flower records
The specimens examined in this paper were collected on the fl owers of Aster var.

Habitat
This species has been collected in mountainous areas in Japan and South Korea.The collecting sites are shown in Fig. 23A, C (A = Nagano Pref., Japan; C = Mt.Gariwangsan, South Korea).

DNA barcodes
The COI gene sequences are deposited as DNA barcodes of L. (D.) virideglaucum in the DDBJ under accession numbers LC027537 and LC027538.These numbers are also available in GenBank.Murao, Ebmer & Tadauchi, 2006 Figs 4C, 5G-I, 12D

Diagnosis
This species is separated from the other members of the atroglaucum subgroup by a combination of the following characters: disc of male S4 with sparse hairs (Fig. 4C); male S5 deeply ∩-shaped apically (Figs 4C, 5H); and gonostylus of male genitalia large, obliquely truncated in lateral view (Murao et al. 2006, Fig. 11B).It may be closely related to L. taiwanense Murao sp.nov.from Taiwan in sharing the male S5 without a groove, the apical margin of male S5 incurved, and the ventral retrorse lobe of male genitalia short.

Flight period
Female: April to October.Male: June to November.

Flower records
Twelve species in 5 families were reported as the fl oral records in Japan by Goubara et al. (2004

Habitat
This species has been collected in mountain areas in Japan.One of the collecting sites in Japan (Kumamoto Pref., Kyushu) is shown in Fig. 23B.

Diagnosis
This species is separated from other members of the atroglaucum subgroup by a combination of the following characters: male S4 basally with sparse and moderately long erect hairs (Murao & Tadauchi 2008; Fig. 2H); male S5 with a linear shallow groove (Fig. 5K); male S6 with a pair of thin hair tufts; and gonostylus of male genitalia truncated on top (Murao & Tadauchi 2008; Fig. 2B-C).

Female
Unknown.

Distribution
Japan (Hokkaido, northern and central Honshu).

Flight period
Male: August to October.

Diagnosis
This species is separated from other members of the atroglaucum subgroup by a combination of the following characters: male head wider than long; disc of male S4 with sparse and short hairs (Fig. 4E); male S5 gently incurved apically (Fig. 5N); and the shape of gonostylus of male genitalia (Fig. 11C-D).

Etymology
The specifi c name is derived from the type country, Taiwan.
ABDOMEN.Discs of T1-T3 with sparse fi ne PP.T1 smooth except for punctures.T2 basally and apically lineolate, T3-T5 over entire surface.S4 and S6 normal shaped, not modifi ed.S5 gently incurved apically (Fig. 5N).S7-S8 (Fig. 11F): S7 with triangular median process, apex not exceeding S8; S8 medially weakly projecting, but not forming median process.GENITALIA (Fig. 11A-E).Gonobase short, fl at at bottom, ventral arms connected with each other at upper ends; gonocoxite smooth, gently sloped in lateral view, and inner dorsal margin angulate approximately at basal ⅓ ; gonostylus small, truncated apically in lateral view, located on top of gonocoxite, and with sparse short and a few long hairs; ventral retrorse lobe leaf-shaped, short, with moderately dense short setae ventrally; penis valve with low cleft on top.

Female
Unknown.

Variation
The postgena nearly smooth in fi ve paratypes (holotype and rest of paratypes weakly tessellate).

Distribution
Taiwan.

Flight period
Male: June to September.

Diagnosis
This species is closely related to Lasioglossum alishanense Murao sp.nov., L. sanitarium (Blüthgen, 1926) and L. sichuanense Fan & Ebmer, 1992 from the northern Oriental Region, as stated above.For the differences between this species and L. alishanense, see the Key.It is also separated from the remaining two species by having the disc of the male S5 without an apical depression (Fig. 14B).The female cannot be clearly separated from the related species, as stated above.(Blüthgen, 1923).B. Lasioglossum (Dialictus) sanitarium (Blüthgen, 1926).C.  Pref., 22 Aug. 1988 (I. Togashi, ELKU).

Additional description
LABRUM (Fig. 15C-D).Basal area approximately 2.3 × as wide as long in female, 3 × in male; basal elevation of female moderately developed, that of male absent; distal process of female slender, nearly as long as basal area, and without lateral projection, that of male absent; keel of distal process narrow, apically pointed; labral fi mbria acutely pointed at apex in both sexes.
MALE GENITALIA (Fig. 16A-E).Gonobase nearly fl at at bottom, ventral arms connected with each other at upper ends; gonocoxite smooth, gently sloped in lateral view, and inner dorsal margin gently angulate European Journal of Taxonomy 137: 1-50 (2015) at approximately basal 1/3; gonostylus large, located at top of gonocoxite, with dense short setae on inner surface; ventral retrorse lobe moderately long but not reaching gonobase, with dense short setae ventrally and relatively long blunt setae laterally; penis valve higher than gonocoxite, with high cleft on top.

Distribution
Russian Far East (Sakhalin) and Japan (Hokkaido, northern to central Honshu).Ebmer (1978Ebmer ( , 2006) ) recorded this species from Primorsky and North Korea, respectively, based on female specimens.These records are not included in this paper, because the female cannot be clearly separated from that of some of the related species.

Flight period
Female: May to September in Hokkaido, Japan.
Male: August to October.
The fl ight record of females is based on specimens collected from the eastern part of Hokkaido, Japan.This record can be considered accurate, because one of the related species, L. virideglaucum Ebmer & Sakagami, does not sympatrically inhabit this area.

Flower records
In

Biological reference
According to Sakagami & Kuribayashi (1979) and Sakagami et al. (1984), some biological information is available.Nest place and structure: the female prefers to make a nest at the forest edge; the nest structure is the IIIa type of Sakagami & Michener (1962).Social structure and life cycle: the brooding period of the overwintered generation is from early May to late July, in Sapporo city, Hokkaido; most of the overwintering females stay communally in the natal nests; the nest are communally reused in the next brooding season, hence many colonies are semisocial or sometimes delayed eusocial from the beginning of spring activities; females living in the same nests are mostly of the same generation and seem to be sisters in most cases, although some nests are inhabited by a two-year-old female and her daughters; all cohabiting females are inseminated, but only one of them has fully developed ovaries at the peak of brooding season, the others with undeveloped ovaries participate in foraging.

Diagnosis
This species may be closely related to Lasioglossum problematicum, L. sanitarium, and L. sichuanense, as stated above.For the differences between this species and L. problematicum, see the Key.It is separated from the two other related species by the disc of the male S4 having short and sparse hairs (Fig. 13D), the male S5 without an apical depression (Fig. 14H), and the shape of gonostylus of male genitalia (Fig. 18C).

Etymology
The specifi c name is derived from the type locality, Mt.Alishan in Taiwan.

Female
Unknown.

Distribution
Taiwan.MURAO R. et al., Dialictus of Japan, the Korean Peninsula, and Taiwan male F2 1.5-1.7 × as long as its diameter, 5) female mesocutum and mesopleuron punctate, 6) length of metapostnotum as long as or longer than mesoscutellum in both sexes, 7) female striate, more or less shiny, 8) posterior surface of propodeum usually with complete lateral carina in both sexes, 9) male metasoma elongate, 10) female T1 apically with fi ne lineolate or shagreened, 11) T2-T4 with apical fi mbriae or developed lateral spots in both sexes, 12) male metasomal sterna not modifi ed, 13) gonostylus of male genitalia small, rounded triangular, trapeziform or elongate elliptical, and not narrowed at base and 14) ventral retrorse lobe of male genitalia rounded, elliptical, sometimes triangular.However, it is very diffi cult or impossible to separate from all other group based on these character states.This group needs a revision of the diagnostic characters through detailed morphological and phylogenetic studies.

Distribution
Palaearctic to northern Oriental Region.It is diverse in the western Palaearctic Region.
MALE GENITALIA (Fig. 21A-D).Gonobase nearly fl at at bottom, ventral arms connected with each other at upper ends; gonocoxite smooth, gently sloping in lateral view, inner and outer dorsal margins nearly parallel; gonostylus small, bud-like in lateral view, located at top of gonocoxite, with sparse short hairs; ventral retrorse lobe tongue-like, long, apex reaching gonobase, with short hairs ventrally, apical hairs longer than around one; penis valve higher than gonocoxite, without cleft on top.

Distribution
Russian Far East (Yakutia, Khabarovsk and Primorsk Terr., Irkutsk Prov.), Mongolia and the Korean Peninsula (north, new record for south).
European Journal of Taxonomy 137:

Discussion
Twelve species in total are recognized in the countries studied.All species, except for Lasioglossum (Dialictus) ellipticeps and L. (D.) virideglaucum, are endemic in Far East Asia.The number of species per country is as follows: 7 in Japan, 4 in the Korean Peninsula and 3 in Taiwan.We could not examine enough material of L. (Dialictus) from either the Korean Peninsula (particularly, from the sample of North Korea) or Taiwan in the present study to defi nitively survey the fauna.The number of species in both countries will likely increase, resulting in additional taxonomic studies of the L. (Dialictus) fauna.In the present study, all L. (Dialictus) species from Taiwan are endemic.The other subgenera of Taiwanese Lasioglossum may include many endemic species according to the fi rst author's preliminary examination of Taiwanese Lasioglossum specimens (Murao unpublished).In eastern Asia, Taiwan (as a consequence of the isolation from or land-bridge formation with the continent) and the Ryukyu Islands (Japan, with its many endemic Lasioglossum species, see Murao 2012;Murao & Tadauchi 2006, 2009b;Murao et al. 2009bMurao et al. , 2010) ) would be important areas to consider in order to investigate the allopatric speciation of Lasioglossum.
AOD = antennocular distance (shortest distance between outer margin of antennal socket and inner margin of compound eye) BL = body length (from antennal base to tip of pygidial plate) CAL = clypealveolar distance (between lower margin of antennal socket and lower margin of supraclypeus in frontal view) CPL = clypeal length (between upper and lower margins of clypeus in frontal view) EL = eye length EW = eye width (maximum length and width of the compound eye) Fn = nth antennal fl agellomere FnL = length of nth fl agellomere (measured along the ventral surface) FnW = width of nth fl agellomere (measured from dorsal and ventral surfaces of fl agellomere) GW = genal width (maximum width of the genal area when seen in lateral view) HL = head length (from top of vertex to lower margin of clypeus) HW = head width (between outer margins of compound eyes in frontal view) IAD = interantennal distance (between inner margins of antennal socket) IOD = interocellar distance (between lateral ocelli) IS = interspace between punctures (e.g., IS 0.5d means 1/2 of the diameter of a puncture) LOD = lower interorbital distance MNL = metanotal length MOD = maximum interorbital distance MURAO R. et al., Dialictus of Japan, the Korean Peninsula, and Taiwan MPL = metapostnotal length MsW = maximum mesosomal width MtW = maximum metasomal width OCD = ocelloccipital distance (shortest distance between margins of lateral ocellus and vertex when seen in upper view) OOD = ocellocular distance (shortest distance between lateral ocellus and inner margin of compound eyesternum SPL = scape length (a straight line from base to tip of scape) Tn = nth metasomal tergum UOD = upper interorbital distance WL = wing length (length of fore wing from the apical point to the base including tegula)