Lasioglossum (Eickwortia) alexanderi (McGinley)

Hinojosa-Díaz, Ismael A., Martínez Cervantes, Ana Celeste & Gibbs, Jason, 2025, Discovery of the males of Lasioglossum (Eickwortia) hienae and L. (E.) alexanderi, with new distributional records for the species (Apoidea, Halictidae), ZooKeys 1228, pp. 53-67 : 53-67

Lasioglossum (Eickwortia) alexanderi (McGinley)

Figs 10–15 , 16–18 , 19–21

Eickwortia alexanderi McGinley 1999: 118 (♀).

Material examined.

10 specimens (2 ♂♂, 8 ♀♀). Costa Rica • 2 ♂♂, 7 ♀♀; Puntarenas, Monteverde , 10.3181, -84.8025; 09 Feb 2020; T. McMahon leg; on yellow composite; WRME ; 1 ♀; Puntarenas; Monteverde : 20 / 24 Jun 1986; W. Hanson | G. Bohart leg.; BBSL .

Diagnosis.

The male of L. (E.) alexanderi is unique among all known Western Hemisphere Lasioglossum for the thickened apex of the clypeus above the labrum. The broad hind basitarsus is also unlike any Lasioglossum in the region. The female is entirely brown-black, mandibles bidentate, and wings entirely infuscate. The metapostnotum is crescent-shaped, defined apically by a sharp edge, and covered by subparallel. longitudinal carinulae (Fig. 21 ; McGinley 1999: fig. 13). An undescribed female collected simultaneously is remarkably similar, but the metapostnotum has a smooth apicolateral area, not sharply defined from the carinulate portion. This undescribed female is notably smaller, with varying levels of golden-green reflections and the apical terga are orange.

Description.

Male:

Length 8.3–9.2 mm.

Head length 2.4–2.5 mm. Head width 2.8–2.9 mm. Intertegular span 2.0– 2.2 mm.

Forewing length 7.7–8.3 mm.

Maximum metasomal width (T 3) 2.3–2.35 mm.

Structure. Head wider than long (length / width ratio = 0.85–0.91). Gena width at midlength 1.1–1.2 × width of contiguous section of compound eye in lateral view (Fig. 10 ). Supraclypeal area weakly protuberant. Clypeus width approximately twice length, width / length ratio = 2.2, projecting approximately half its length below lower margin of eyes (Fig. 11 ). Clypeal apex thickened, half-length of labrum (Fig. 13 ). Ocellocular distance 2.5 × lateral ocellar diameter, slightly greater than distance between lateral ocellus and hind margin of vertex, and 1.3 × interocellar distance (Fig. 12 ). Compound eyes convergent below, upper ocular distance 1.4 × lower ocular distance (Fig. 2 ). Hypostomal carinae strong, subparallel; anterior angle rounded. Antennal scape short, not reaching median ocellus; pedicel wider than long, three quarters length of flagellomere 1 (subsequent flagellomeres missing). Labrum short without apical process. Mandible simple, relatively broad at midlength, nearly reaching opposing clypeal angle (Fig. 13 ). Pronotum maximum width 2.7–2.8; dorsolateral angle orthogonal; pronotal ridge strongly angled, interrupted by oblique sulcus; pronotal lobe with anterior carina. Inner metatibial spur ciliate, subequal in size to outer metatibial spur. Tegula ovoid. Forewing veins 1 rs-m and 2 rs-m not noticeably weak; hamuli arranged 3-1 - 2.

Surface sculpture. Face tessellate-granular below antennal sockets, scabriculous above (Fig. 11 ), Gena and subgena striolate in oblique view, outer subgena polished. Mesoscutum and mesoscutellum polished, anteromedial mesoscutum imbricate, becoming striolate anterolaterally (Fig. 13 ). Metapostnotum with dense, regular carinulae, slightly depressed at apex (Fig. 13 ). Mesepisternum transversely striolate on upper half, vertically striolate on anterior lower half, more irregularly sculptured towards mesocoxa. Metepisternum transverse carinulae above, imbricate, irregularly sculptured below.

Propodeum lateral surfaces similar to lower metepisternum, posterior surface tessellate noticeably.

Terga polished.

Color. Body blackish brown, with the following remarks: supraclypeal area with dull golden-green reflections, gena hints of green in certain lights, posterior surface of flagellomere 1 dark. Tegula dark brown (Fig. 12 ). Legs dark brown, pretarsal claws reddish brown (Fig. 15 ). Forewing membrane weakly infuscate throughout, with green and purple highlights; wing veins and pterostigma brown (Fig. 10 ). Metapostotum with blue tinge between carinulae. Terga blackish brown, with narrow rims reddish brown and ventrally reflexed portions amber; sterna amber (Fig. 15 ).

Pubescence. Head and mesosoma with erect branched setae (1.5–2.5 OD); tomentum sparse on clypeus, paraocular and supraclypeal areas (Fig. 11 ). Pronotal collar, lobe and adjacent pre-episternum with tomentum. Meso- and metacoxae and trochanters ventrally with dense velvety setae, extending onto ventral surface of mesofemur (Fig. 14 ), otherwise legs with short subappressed setae. Apical half of pro- and mesotibiae with long setae ventrally, somewhat curved apically becoming straight towards apex. T 1 anterior face with erect setae, remaining terga with sparse short setae, except longer on premarginal lines of T 5 – T 6. S 1 – S 4 nearly bare, S 5 – S 6 with long setae.

Genitalia. As in Figs 16–18 . S 7 with slender median process, S 8 broadly rounded apically. Gonocoxite dorsally with inner edge subparallel for length approximately equal to gonobase (Fig. 17 ); gonostylus moderately elongate, rounded apically (Fig. 18 ); retrorse lobe present, moderately long, slender, rounded apically (Fig. 16 ); volsella with prominent lateral lobe.

New distributional records

Although the holotype of L. alexanderi is lost, the description and figures are sufficient to recognize this unique species. At this point a neotype designation is not needed, and there is still hope the holotype may reemerge once more material in the former possession of McGinley is examined. The novelty of the male and co-occurrence with the female supports the association. The undescribed female co-occurring with L. alexanderi is unlikely to be the female based on the similar structure of the male and female metapostnotum, in addition to body color and size. The new collection site is approximately 70 km west of the type locality ( Costa Rica; Heredia; 8.7 km N Varablanca).

Figures

Figures 10–15. Male of Lasioglossum (Eickwortia) alexanderi 10 lateral habitus 11 face 12 dorsal habitus 13 mandibles and lower section of head 14 anterior surface of mesofemur 15 view of sterna.

Figures 16–18. Male genitalic capsule of Lasioglossum (Eickwortia) alexanderi 16 ventral aspect 17 dorsal aspect 18 lateral aspect.

Figures 19–21. Female of Lasioglossum (Eickwortia) alexanderi 19 lateral habitus 20 face 21 dorsal view of mesosoma.

Figures 1–5. Male of Lasioglossum (Eickwortia) hienae 1 lateral habitus 2 face 3 dorsal habitus 4 dorsal view of mesosoma 5 ventral view of metasoma.