Austrothurgus Gonzalez & Engel, 2013

Gonzalez, Victor H., Engel, Michael S. & Griswold, Terry L., 2013, The lithurgine bees of Australia (Hymenoptera: Megachilidae), with a note on Megachile rotundipennis, Journal of Melittology 2013 (11), pp. 1-19 : 3

Austrothurgus Gonzalez & Engel , new genus

ZooBank urn:lsid:zoobank.org:act:466F096E-7492-4B12-BD0B-4DD1A6E9D220

TYPE SPECIES: Lithurgus rubricatus Smith, 1853 .

DIAGNOSIS: This genus can be readily distinguished from all other lithurgine genera by the following combination of characters: arolia present in males, absent in females; first flagellomere long in both sexes, at least 1.5 times longer than broad, about twice as long as second, which is much broader than long; female facial prominence mostly involving base of clypeus; and male metabasitarsus with distinct, strong carina on inner surface ( Figs. 5 , 10 , 15 ).

DESCRIPTION: Robust, middle-sized species (10‒15 mm in body length) with apical fascia on metasomal terga; epistomal sulcus present between tentorial pits in both sexes; labrum about as long as clypeus, with strong transverse ridge at base; facial prominence involving base of clypeus, poorly developed in male; maxillary and labial palpi tetramerous (four-segmented); first flagellomere long, at least 1.5 times longer than broad, about twice as long as second, which is much broader than long; pretarsal claws simple in female, cleft in male; aroliae absent in female, present in male; female tibiae tuberculate on outer surfaces, in male tubercles reduced on mesotibia and absent on metatibia; metabasitarsus slightly shorter than metatibia in female, slightly longer than half metatibial length in male; metatibial spurs slender, not or scarcely bent apically.

ETYMOLOGY: The new genus-group name makes reference to the Australian distribution of this taxon. The name is masculine.

COMMENTS: Austrothurgus is most similar to Lithurgus in the proportions of the first and second flagellomeres in both sexes, but it can be distinguished by the presence of the arolia in the male, the female facial prominence mostly involving the base of the clypeus, and the male metabasitarsus with an inner asetose area projecting into a distinct carina. In Lithurgus the arolia are absent or rudimentary in both sexes, the female facial prominence involves the base of the clypeus and part of the supraclypeal area, and the inner asetose area of the male metabasitarsus is usually absent, and when present (e.g., L. atratus Smith , L. huberi ), it does not project into a distinct carina.

INCLUDED SPECIES: In addition to the type species, A. rubricatus , the genus includes A. cognatus ( Smith, 1868) and A. malgaru Gonzalez, Engel, & Griswold , new species (vide infra).

Figures

Figures 1–5. Photomicrographs of lectotype female (1–4) and male (5) of Austrothurgus rubricatus (Smith). 1. Lateral habitus. 2. Dorsal habitus. 3. Lateral view of head. 4. Facial view. 5. Male metatarsus, depicting modification of metabasitarsus.

Figures 6–10. Photomicrographs of lectotype female (6–9) and male (10) of Austrothurgus cognatus (Smith). 6. Lateral habitus. 7. Facial view. 8. Lateral view of head. 7. Detail of vertex. 10. Male metatarsus (apex missing), depicting modification of metabasitarsus.

Figures 13–16. Photomicrographs of holotype male of Austrothurgus malgaru, new species. 13. Facial view. 14. Detail of sculpturing on mesoscutum and mesoscutellum. 15. Metatarsus, depicting modification of metabasitarsus. 16. Apex of metasoma.