Lithurgus atratiformis Cockerell

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 : 10-11

Lithurgus atratiformis Cockerell

( Figs. 20–22 )

Lithurgus atratiformis Cockerell, 1905: 295 . Holotype: NHML No. 17.a.2098; ♀, NW coast of Australia.

DIAGNOSIS: Among Australian Lithurgus , L. atratiformis is most similar to L. atratus Smith in the black or dark brown sternal scopa, distal terga with dark setae ( Fig. 20 ), and mesoscutum with strong rugulae ( Fig. 21 ). The female can be distinguished from that species primarily by its larger body size (head width 4.5 mm vs. 4.2 mm) and broader facial prominence ( Fig. 22 , about two-thirds length of lower interorbital distance vs. about half length of lower interorbital distance).

COMMENTS: Cockerell (1905) did not state the number of specimens on which he based the description of L. atratiformis but the female specimen deposited in the NHML has a label in Cockerell’s handwriting that reads “type”. Cockerell usually labeled one specimen as “type” and the others in the type series as “cotypes”, corresponding to the modern holotype and paratype concepts. A designation of lectotype is therefore not necessary as the NHML specimen is assuredly a holotype .

As indicated by Michener (1965), L. atratiformis is morphologically very similar to L. atratus , L. scabrosus (Smith) , and L. collaris Smith and they may be conspecific. Except for subtle differences in body size, we did not find consistent morphological differences between the male specimens associated with females that matched the type of L. atratiformis and those males associated with females that matched the type of L. atratus . For this reason, the males of both species are not separated in the key.

Figures

Figures 20–22. Photomicrographs of holotype female of Lithurgus atratiformis Cockerell. 20. Lateral habitus. 21. Detail of sculpturing on mesoscutum and mesoscutellum. 22. Facial view.