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Identification Summary: Small; head relatively large, wide, and cheeks wide; hypostomal cavity widely diverging towards the mouth; tooth on mandible different from most other species with more of a triangular bump rather than the thumb of a mitten type of tooth; pits widely spaced on scutum; T1 hair fan complete; mesepisturnum very smooth.
Reprinted with permission from: Mitchell, T.B. 1960 Bees of the Eastern United States. North Carolina Agricultural Experiment Station Technical Bulletin No. 141.
FEMALE—Length 4 mm.; head and thorax greenish, abdomen piceous; pubescence very short and thin, entirely pale; head slightly broader than long; clypeus quite flat, projecting only slightly below suborbital line; eyes slightly convergent below; lateral ocelli slight- ly nearer margin of vertex than to each other, subequally distant from eyes and each other; mandibles rather elongate, with an inner median angle, but without a distinct subapical tooth; median apical projection of labrum elongate; cheeks somewhat broader than eyes; upper half of face shining, punctures fine, but deep and distinct, well separated but not sparse, becoming more minute and obscure on vertex and upper portion of cheeks, these microsopically striate below, hypostomal carinae strongly divergent apically; lower half of face shining, more obscurely and sparsely punctate, punctures widely separated on supraclypeal area and clypeus; scutum and scutellum shining (fig. 99), punctures minute, quite sparse in center of discs, becoming somewhat closer laterally; pleura rather dull, finely roughened but without distinct punctures or reticulations; dorsal area of propodeum finely striate along base, apical margin quite smooth and rounded, lateral faces smooth and shining; wings hyaline, veins and stigma pale testaceous; tegulae testaceoushyaline; legs brownish-piceous basally, becoming yellowish apically; abdominal terga somewhat shining, punctures exceedingly minute and obscure, barely visible, apical margins rather broadly impressed, more reddish, entirely impunctate, apical terga quite bare.
TYPES—Holotype: Female, Grandfather Mt., N. C., June 27, 1952 (Mitchell, on Hydrangea) [author’s coll.]. Paratypes: NORTH CAROLINA: 4females, Cruso, Haywood Co., June 25, 1934 (on Hydrangea);
22 2, Blue Ridge Pkwy. 3500 ft., Buncombe Co., June 22, 1954; 1 female, Doughton Park, Aug. 26, 1954; 1 female, Cumberland Knob Park, Aug. 3, 1954 (on Rhus) (all Mitchell); 2 females, Haywood Co., June 17, 1955 (H. V.Weems, Jr., on Hydrangea); 12, Black Mts., Aug. 1912 (Beutenmuller). TENNESSEE: 1 female, Fentress Co., Allardt, 1800 ft., Aug. 13, 1924 (T. H. Hubbell). WEST VIRGINIA: 12, Nicholas Co., Aug. 13, 1957 (on Aralia) ; 1 female, Greenbrier Co., Aug. 13, 1957 (both H. V. Weems, Jr.). PENNSYLVANIA: 2 females, Decker Valley, July 19, 1943 (V. R. Haber). INDIANA: 1 female, Morgan-Monroe, St. Forest, July 14-16, 1937, Forest insect survey (Montgomery). WISCONSIN: 1 female, St. Croix Falls, May 1939 (Don Murray). MINNESOTA: 1 female, Houston Co., May 22, 1937 (C. E. Mickel). MICHIGAN: 1 female, Sanilac Co., May 3, 1952 (R. R. Dreisbach). NEW YORK: 5 females, Granby Center, Oswego, July 17, 1956 (prey of Philcinthus) ; 1 female, South Hill, Ithaca, Aug. 25, 1957 (both Evans); 1 female, Ringwood, Aug. 25, 1947 (C. H. Robinson); 1 female, Slaterville, May 22, 1950; 1 female, Tompkins Co., July 24, 1958 (on Daucus carota) 12 females, Tompkins Co., July 18, 24 & 25, 1958 (J. Graham); 17 females, Tompkins Co., July 17, 20 & 27, 1958 (on Melilotus alba); 13
females, Tompkins Co., May 24, 27 and June 1, 1958 (on Barbarea vulgaris) ; 1 female, Tompkins Co., Aug. 22, 1958 (sweeping weeds) (all R. A. Morse). MASSACHUSETTS: 1 female, Needham, May 30, 1958 (Mitchell, on Viburnum); 7 females, Waltham, July 1, 10, 15 & 17, 1957 (on Melilotus alba); 1 female, Waltham, April 29, 1957 (on Tarazacum officinale) (both R. A. Morse). CONNECTICUT: 2 females, Stamford, Aug. 28 & 30, 1948 (S. W. Bromley); 1 female, Mt. Pisgah, Colebrook, Aug. 3, 1921 (W. M. Wheeler); 1 female, Waterbury, Aug. 14, 1945 (P. H. Timberiake, on Deutzia gracilis). VERMONT: 2 females, Weston, July 31, 1901 (Davis Coil.); NEW HAMPSHIRE: 5 females, Meredith Center, July 20, Aug. 3 & 8, 1957 (on Solidago); 8 females, Meredith Center, July 14, 1957 (on Apocynum androsaemifolium); 1 female, Meredith Center, May 30, 1957 (on Rubus) (all R. A. Morse); 2 females, Lancaster, Aug. 23, 1928 (on Aster umbellatus) and May 31, 1917 (P. H. Timberlake). NEW BRUNSWICK: 3 females, Charlotte, Co., Aug. 13, 1956 (W. T. A. Neilson). QUEBEC: 2 females, Hudson Heights, July 24-30 and Sept. 1-4, 1956 (Lindberg).
Paratypes are in the collections of Cornell University, the University of Rhode Island, the University of Minnesota, the Florida Plant Board, the New Brunswick Dept. of Agriculture, Purdue University, the Museum of Comparative Zoology, R.R. Dreisbach, T. H. Hubbell, R. A. Morse, S. W. Frost, P. H. Timberlake, H. Lindberg of Helsinki, Finland and the author.
This species bears some resemblance to inconspicuus (Smith) and apopkensis (Robertson), but differs from both in the lack of inner mandibular teeth and in the divergent hypostomal carinae. There is some variation in the form of the head, certain of the paratype specimens having much broader and more swollen cheeks. The name of this species was suggested by P. H. Timberlake, having been used as a manuscript name on the Lancaster, N. H. specimens which were received from him.
Retrieved from: Gibbs, J. 2010. Revision of the metallic species of Lasioglossum (Dialictus)in Canada (Hymenoptera, Halictidae, Halictini). Zootaxa; 2591, 136-140
Dialictus heterognathus Mitchell, 1960: 397. ♀.
Holotype. ♀ USA, North Carolina, Grandfather Mt., 27.vi.1952, [NCSU]. Examined.
Dialictus banksi Mitchell, 1960: 434. ♂.
Holotype. ♂ USA, North Carolina, West End, 14.vi.1950, (Mitchell); [NCSU]. Examined.
Taxonomy. Knerer and Atwood, 1963: Dialictus heterognathus ♂, p. 167 (description); Knerer and Atwood,
1966: D. heterognathus, p. 882 (synonymy); Krombein, 1967: Lasioglossum (Dialictus) heterognathum, p.
463 (catalogue); Hurd, 1979: Dialictus heterognathus, p. 1966 (catalogue); Moure & Hurd, 1987: Dialictus
heterognathus, p. 103 (catalogue).
Diagnosis. Females of L. heterognathum can be recognized by the diagnostic combination of a large and
wide head (length/width ratio = 0.92–0.96), gena wider than eye (Fig. 114D), divergent hypostomal carinae
(Fig. 114E) and fine mesoscutal punctures. They are most similar to L. imitatum and L. apocyni which both
have parallel hypostomal carinae.
Males of L. heterognathum can be recognised by polished moderately dense facial tomentum limited to
lower paraocular area, elongate flagellomeres (length/width ratio = 1.50–1.85), obtuse dorsolateral angles of
the pronotum, mesoscutum dull due to weak microsculpture and sparse punctures on central disc (i=2–3d),
distinct fine punctures on mesepisternum (i=1–3d), and apical impressed areas of the metasomal terga
impunctate. They are most similar to the eastern USA species L. wheeleri which have acute dorsolateral
angles of the pronotum.
Redescription. FEMALE. Length 4.64–6.19 mm; head length 1.08–1.63 mm; head width 1.18–1.68 mm;
forewing length 3.23–3.97 mm.
Colouration. Head and mesosoma bluish green. Clypeus with apical 2/3 blackish brown and basal portion,
and supraclypeal area with brassy reflections. Antenna dark brown, flagellum with ventral surface reddish
brown to orange. Mesoscutum often with substantial green reflections. Tegula reddish amber. Wing membrane
subhyaline, venation and pterostigma amber. Legs brown, medio- and distitarsi reddish brown. Metasoma
blackish brown, terga and sterna with apical margins brown to brownish yellow.
Pubescence. Dull white. Sparse. Head and mesosoma with moderately sparse woolly hairs (1–1.5 OD),
longest on genal beard, metanotum and mesopleuron (2–2.5 OD). Paraocular area with sparse subappressed
hairs. Gena with sparse tomentum. Propodeum with moderately dense plumose hairs on lateral and posterior
surfaces (2–2.5 OD). Metasomal terga with sparse, fine setae. T1 acarinarial fan with wide dorsal opening.
T2–T3 basolaterally and T4–T5 entirely with sparse, scattered tomentum.
Surface sculpture. Face polished, faintly imbricate, punctation fine. Clypeus polished, punctation sparse
(i=1–5d). Supraclypeal area with punctation sparse (i=2–3d). Lower paraocular and antennocular areas with
punctation moderately sparse (i=1–2.5d). Upper paraocular area and frons with clearly separate punctures
(i=1–1.5d). Ocellocular area minutely punctate. Gena polished. Postgena imbricate-lineolate. Mesoscutum
polished, faintly imbricate, punctation fine, moderately sparse between parapsidal lines (i=2–3d), moderately
dense laterad of parapsidal line (i=1–1.5d) and dense on anterolateral portion (i≤d). Mesoscutellum polished,
medial line punctation distinctly separated (i=d). Axilla punctate. Metanotum imbricate. Preëpisternum and
mesepisternum imbricate, rugulose above. Metepisternum with dorsal third weakly rugoso-striate, ventral
portion imbricate. Metapostnotum incompletely, weakly striate. Propodeum with dorsolateral slope imbricate,
lateral and posterior surfaces tessellate. Metasomal terga coriarious, punctation on basal halves sparse (i=1.5–
3d), apical half impunctate (except along premarginal line).
Structure. Head large and quadrate, wide (length/width ratio = 0.92–0.96), broader than mesosoma. Eyes
weakly convergent below (UOD/LOD ratio = 1.05–1.14). Clypeus projecting 1/3–1/2 below suborbital line,
apicolateral margins convergent. Antennal sockets close (IAD/OAD ratio < 0.5). Frontal line carinate, ending
>2 OD below median ocellus. OOD greater than IOD. Gena wider than eye. Hypostomal carinae divergent
towards mandible bases. Inner metatibial spur pectinate with 3–4 teeth. Metapostnotum short (MMR ratio =
1.21–1.40), posterior margin broadly rounded onto posterior surface. Propodeum with oblique carina weak,
lateral carina not reaching dorsal margin.
MALE. Similar to female except for the usual secondary sexual characters and as follows. Length 4.70–
5.37 mm; head length 1.36–1.49 mm; head width 1.34–1.39 mm; forewing length 3.54–3.97 mm.
Colouration. Flagellum with ventral surface orange-yellow. Femoral-tibial joint and tarsi brownish yellow;
protibia infused with brownish yellow.
Pubescence. Clypeus, supraclypeal area, and paraocular area with moderately dense tomentum largely
obscuring surface. Frons with sparse tomentum not obscuring surface. Metasomal sterna sparsely pubescent.
Surface sculpture. Gena lineolate. Mesepisternum punctate (i=1–3d). Metapostnotum longitudinally striate,
not reaching posterior margin. Propodeum with dorsolateral slope rugose. Metasomal terga more deeply
punctate (i=2–3d), apical impressed margin impunctate.
Structure. Head elongate (length/width ratio = 0.99–1.07). Eyes strongly convergent below (UOD/LOD
ratio = 1.57–1.64). Clypeus projecting 1/2 below suborbital line, apicolateral margins subparallel. Antennal
sockets distant (IAD/OAD ratio > 1.5). Frontal line carinate, ending >2 OD below median ocellus. OOD
greater than IOD. Gena narrower than eye. Postgena impressed adjacent to hypstome. Hypostomal carinae
parallel. Pedicel subequal to F1. F2 length 2.0–2.2X F1. F2–F10 moderately elongate (length/width ratio =
1.50–1.85). Metapostnotum moderately elongate (MMR ratio = 1.33–1.40), posterior margin rounded onto
posterior surface.
Terminalia. S7 with median lobe strongly clavate, apex rounded (Fig. 115G). S8 with apicomedial margin
weakly convex (Fig. 115G.). Genitalia as in Fig. 115D–F. Gonobase with ventral arms widely separated.
Gonostylus small, dorsal setae elongate. Retrorse lobe narrow, attenuated apically.
Range. Nova Scotia to Ontario, west to Minnesota, and south to North Carolina (Fig. 113).
Additional material examined. CANADA: NEW BRUNSWICK: 2♀♀ (paratypes) Charlotte Co.,
13.viii.1956 (W.T.A. Neilson); 1♀ Fredericton, 25.v.1961 [CNC]; ONTARIO: 1♀1♂ Constance Bay, 13–
19.viii.1977 (M. Sanborne); [PMAE]; 2♀♀Forks of Credit, 12.viii.1969 (P. MacKay); 2♀♀4♂♂ Forks of
Credit, 21.viii.1969 (P. MacKay); 2♀♀Forks of Credit, 29.viii.1969 (P. MacKay); [ROM]; 4♀♀ Madoc,
10.v.1962 (G. Knerer); [ROM; PCYU]; 1♀ Toronto, York University N43.77175 W079.4965, 20.iv.2006 (J.
Gibbs); [PCYU]; QUEBEC: 2♀♀ Gatineau Pk., Mountian Rd., 12.vii.1965 (P.S. Corbet); [PMAE]; USA:
MAINE: 1♀ Acadia, Mt. Desert Camp, 21.vii.1978 (P.E. Hallet); [PHPC]; MICHIGAN: 1♀ Huron Co., Port
Hope, 8.v.1965 (J. & L. Donahue); [CUIC]; MINNESOTA: 1♀ Minnetonka, U. of Minnesota Arboretum,
vi.2005 (L. Packer); NEW HAMPSHIRE: 1♂, 22.viii.1960, on Solidago, R.A. Morse; [PCYU]; NEW YORK:
1♂ Schuyler Co., Hector Land Use Area, nr Reynoldsville, 16.viii.1977 (G. & K. Eickwort); [CUIC]; NORTH
CAROLINA: 1♀ Great Smoky Mountain N.P., Cataloochee overlook, N35.63997 W083.06017, 6.viii.2006
(C. Sheffield); [GSNP]; WEST VIRGINIA: 1♀ Hampshire Co., N38.4049 W078.5153, 7.vii.2002 (S.W.
Droege); 1♀ Hampshire Co., N38.4376 W078.6083, 7.vii.2002 (S.W. Droege); 1♀ Hampshire Co., N38.415
W078.5012, 7.vii.2002 (S.W. Droege); 1♀ Hampshire Co., N39.2325 W078.5174, 29–30.v.2005 (S.W.
Droege); [PCYU]; WISCONSIN: 15♀♀ Dane Co., Indian Lk., 24.vii.1996 (R.A. Henderson); [IRCW]..
Floral records. ANACARDIACEAE: Rhus, APIACEAE: Daucus carota, APOCYNACEAE: Apocynum
androsaemifolium, ARALIACEAE: Aralia, ASTERACEAE: Doellingeria umbellata, Solidago, Symphyotrichum
lateriflorus, Taraxacum officinale, BRASSICACEAE: Barbarea vulgaris, CAPRIFOLIACEAE: Viburnum,
FABACEAE: Melilotus alba, HYDRANGEACEAE: Deutzia gracilis, Hydrangea, ROSACEAE:
Malus, Rubus.
Comments. Common. Females of L. heterognathum exhibit large variation in head size and shape which
are presumably related to caste differentiation with allometry.
Extracted from Jason Gibbs. 2011. Revision of the metallic Lasioglossum (Dialictus) of eastern North America (Hymenoptera: Halictidae: Halictini.) Zootaxa.
Lasioglossum (Dialictus) heterognathum (Mitchell)
Dialictus heterognathus Mitchell, 1960: 397. ♀.
Holotype. ♀ USA, North Carolina, Grandfather Mt., 27.vi.1952, [NCSU]. Examined.
Dialctus banksi Mitchell, 1960: 434. ♂. Lapsus calami.
Holotype. ♂ USA, North Carolina, West End, 14.vi.1950, (Mitchell); [NCSU]. Examined.
Taxonomy. Knerer and Atwood, 1963: Dialictus heterognathus ♂, p. 167 (description); Knerer and Atwood, 1966a: D.
heterognathus, p. 882 (synonymy); Krombein, 1967: Lasioglossum (Dialictus) heterognathum, p. 463 (catalogue); Hurd, 1979: Dialictus heterognathus, p. 1966 (catalogue); Moure & Hurd, 1987: Dialictus heterognathus, p. 103 (catalogue);
Gibbs, 2010b: Lasioglossum (Dialictus) heterognathum ♀♂, p. 136 (redescription, key).
Diagnosis. Female L. heterognathum can be recognised by the following diagnostic combination: hypostomal carinae
divergent towards mandible bases (Fig. 10B), gena wider than eye, mesoscutal punctures fine, and scopa present.
They are similar to L. apocyni and L. imitatum, which both have hypostomal carinae parallel and female L. imitatum have
T3–T4 with coarse white hairs (Fig. 20A).
Male L. heterognathum can be recognised by the following diagnostic combination: facial tomentum dense only on
lower paraocular area; flagellomeres elongate (length/width ratio = 1.50–1.85); dorsolateral angles of pronotum obtuse;
mesoscutum dull due to weak microsculpture, punctures sparse between parapsidal lines (i=2–3d); mesepisternal punctures
fine but distinct (i=1–3d); and apical impressed areas of the metasomal terga impunctate. They are most similar to L.
wheeleri, which have pronotal dorsolateral angles acute.
Range. Nova Scotia to Ontario, west to Minnesota, and south to North Carolina. USA: CT, ME, MI, MN, NH, NY,
NC, PA, VT, WV, WI. CANADA: NB, NS, ON, PQ.
DNA Barcode. Available. Multiple sequences.
Comments. Common. See Gibbs (2010b).
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