Lasioglossum subgen. Callalictus Michener

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Figure 2. Male genitalia capsules: Left – ventral views, Right – dorsal views: A–B, Lasioglossum (Callalictus) aurantiacum; C–D, Lasioglossum (Callalictus) callomelittinum; E–F, Lasioglossum (Callalictus) musgravei.

Subgeneric diagnosis: Body length moderately large (6.75 mm to 9.11 mm), non-metallic, with mesoscutum variously reddish, ochre or dark coloured and metasoma black, reddish brown or ochre coloured (Figs 3A–B, 4A–B, 5A–B); Female: labrum tapered and pointed, margins unmodified; pronotum with prominent dorsolateral angles (Figs 3A, 4A, 5A), mesoscutum surface with a dull sheen, with minute punctures at various puncture densities, propodeum not defined by strong carinae (weak posterolateral or posterior carinae at most), dorsal surface sculpture smooth or with microtessellate pattern; female inner hind tibial spur pectinate, hind basitibial plate pointed, absent on male; both sexes without tergal tomentous bands on metasoma. Male: similar to female in body colour and sculpture (Figs 3C–D, 4C–D, 5C–D); genitalia with elongated, setose gonostyli (Figs 2A–F) (one species with bifid gonostyli: Figs 2C–D), retrorse lobes enlarged, thin and membranous (Figs 2A, 2C, 2E); S4-S5 with weak hair to dense tomentous bands across sternites (Figs 3F, 4F, 5F). Males of L. aurantiacum (Cockerell 1916) and L. musgravei (Cockerell 1929b) with fore tarsal segments horizontally compressed, flattened, apically bilobed and weakly convex dorsally (forebasitarsus ratio of width versus length 0.6), with elongate lateral hair tufts from each tarsal segment (Figs 3D–E, 5D–E, 6), ventral surface of fore and mid tarsal segments dark coloured and with pale white line running down the middle of each segment, mid tarsal segments of these two species similar to fore tarsi but to a lesser degree but width versus length ratio same; male of L. callomelittinum (Cockerell 1910) with fore and mid tarsal segment not modified (forebasitarsus ratio of width versus length 0.2) (Figs 4D–E), ventral inner surface entirely white.

Remarks. Similar to Lasioglossum subgenera Australictus and Parasphecodes but differs by large dorsolateral angles of pronotum, smooth integument of mesosoma and propodeum and pectinate nature of inner hind tibial spur (inner hind tibial spur: Australictus finely serrate to simple; Parasphecodes coarsely serrate). Michener’s (1965: 170) diagnosis for the subgenus Callalictus included the character “third submarginal cell usually receiving both recurrent veins; this condition is rare in other Australian halictids”. Michener (2007) did not repeat this character in the subgeneric diagnosis for the subgenus Callalictus. Examination of the three valid species of the subgenus Callalictus showed only Lasioglossum (Callalictus) callomelittinum has the third submarginal cell receiving both recurrent veins and so this character is not used in the subgeneric diagnosis. The male fore tarsal modification in two species of the subgenus Callalictus is not a common character of Halictini males. Walker (1997) recorded males of four species of Australian Homalictus (H. atrus Walker 1997, H. grossopedalis Walker 1986, H. latitarsis (Friese 1909) and H. maitlandi (Cockerell 1910)) with horizontally compressed and flattened fore and mid tarsal segments and each broadened tarsal segment has lateral hair tufts. The distinct ventral, central white stripe against a dark background colouration, lateral hair tufts, the horizontally compressed, flattened, bilobed and broadened and concave shape associated with the modified fore and mid tarsal segments found in males of two Callalictus species suggests they may be used in mating and the shape of the tarsal segments suggests they may be placed over the eyes of the female.