Megachile minutissima Radoszkowski 1876

Praz, Christophe, Al-Shahat, Ahmed M. & Gadallah, Neveen S., 2021, Taxonomic revision of the subgenus Eutricharaea Thomson in Egypt, with a key to the species and the description of two new species (Hymenoptera, Anthophila Megachilidae, genus Megachile Latreille), Zootaxa 5032 (3), pp. 301-330 : 318-319

Megachile minutissima Radoszkowski 1876

Figs 37–39 .

Megachile minutissima Radoszkowski 1876: 116 , ♀ ♂, “[ Egypt]”.

Megachile uniformis Alfken 1934: 154 , ♀ ♂, “Oase Kharga [ Egypt]”. Holotype ♀, “Sammlung des Ackerbau-Ministeriums, Cairo ”. Preoccupied, not M. uniformis Mitchell 1929 . New synonymy.

Megachile minutuloides Alfken 1936: 316 . Replacement name for M. uniformis Alfken 1934 .

Type material: Two males are preserved in the Radoszkowski collection in ISZP, which are likely syntypes. Since the type locality of M. minutissima is not precise, a neotype may have to be designated for this species if future work suggests the presence of more than one species of this complex in Egypt (see below).

A female paratype of M. uniformis Alfken 1934 has been examined ( ZMHB).

Additional material: EGYPT: 3 ♀, Borgash (Giza), 31.vii.1932, leg. Mabrouk (sweep net) ( PPDD) ; 4 ♂, Shu- bra (Cairo), 3.vi.1916, leg. Qdair ( PPDD) ; 2 ♀, Faiyum, 5.ii.1952, leg. S.L.M ( ASUA) ; 1 ♀, 2♂, Kom Osheim (Fai- yum), 1.viii.1953, leg. Aly ( ASUA) ; 2 ♀, Pyramids (Giza), 21.vii. 1953, leg. H.P. ( ASUA) ; 1 ♀, Wadi Hoff (Cairo), 14.vii.1952, leg. Aly ( ASUA) ; 2 ♂, Faiyum, 5.ii,1952, leg. S.L.M ( ASUA) ; 2 ♂, Pyramids (Giza), 21.vii. 1953, leg. H.P. ( ASUA) ; 1 ♂, Dakhla Oasis (New Valley), 13.v.1918 ( AUCA) ; 1 ♀, Ismailia, 13.vi.1932 ( AUCE) ; 10 ♀ 2 ♂, Luxor, Westbank of Nile River , 25.694N, 32.628E, 1.iv.2018, leg. C. Schmid-Egger ( CES, CPCN) .

Notes: The status of M. minutuloides and more generally species delineation in this group require further work. Alqarni et al. (2014) list useful diagnostic traits for the separation of M. minutissima and the Central Asian species M. terminata Morawitz 1875 . Rebmann (1970) described two additional species, M. babylonica Rebmann 1970 , M. auripubens Rebmann 1970 , from Iraq and Iran, respectively, and provided a key to the males in this group. M. niveascopa Ferton 1908 , described from Algeria also belong to this species complex. A lectotype is designated here for this species, a female labeled as follows: “Museum Paris [printed on blue paper], Laghouat C. Ferton 1910 [handwritten; probably added after description in 1908]; “ Megachile niveascopa roseau Laghouat Fert., éclos 19/9 07 [Handwrit- ten; roseau = reed, éclos = hatched 19.9.07]; “ Lectotype M. niveoscopa des. van der Zanden 1989 [red]”. This lecto- type designation has not been published and is accepted here. A male with identical labels (except “éclos 4/9 07”; and “ paralectotype M. niveoscopa des. van der Zanden 1989”) is designated as a paralectotype. M. niveoscopa may be conspecific with M. minutissima ; specimens of the type series are slightly larger than typical M. minutissima , and the scopa is entirely white, including on S6. Future work is needed to delineate species in this challenging lineage.

With respect to the Egyptian fauna, Alfken (1934) mentions the following differences between M. minutuloides and M. minutissima : T6 with white tomentum (T6 without white hairs in M. minutissima ); scopa mostly entirely white (scopa black on S6, sometimes also S 5 in M. minutissima ); tergal fringes of hairs medially not reduced (tergal fringes of hairs medially reduced in M. minutissima ). Based on the material that we examined, we were not able to segregate our material into two groups following these criteria. In particular, the color of the scopa and the presence of white tomentum on T6 both appear to represent highly variable traits. Consequently, we tentatively place M. minutuloides in synonymy with M. minutissima .

Our molecular analyses suggest considerable variation within M. minutissima , with one clade including specimens from Oman, Morocco, Egypt and Israel, and, sister to that clade, a single specimen from Oman (05488B05) (see above). Within that clade, two specimens from Northern Egypt are weakly separated from specimens from Morocco, Oman and Israel. Future work using DNA barcodes should further examine the status of the different forms allied to M. minutissima ; in particular specimens of the Kharga Oasis, the type locality of M. minutuloides , should be analyzed genetically.

Distribution: Possibly widely distributed in North Africa, the Middle East, the island of Lesbos ( Rasmont et al. 2017), the Arabian Peninsula and possibly Central Asia, although the exact distribution remains unclear due to open taxonomic questions.

Diagnosis: Female: Small Eutricharaea of the M. rotundata group, very similar to M. rotundata , but usually smaller (although some females may be as large as M. rotundata ), vertex particularly finely and densely punctate, punctures half as large as those on mesonotum ( Fig. 37 ) (in M. rotundata , punctures similar in size to those on mesonotum); mesonotum comparatively sparsely punctate with shiny interspaces that are nearly half a puncture diameter long ( Fig. 37 ) (in M. rotundata , punctation on mesonotum dense, nearly areolate). Tergites sparsely punctate as in M. rotundata , but punctures shallower. Clypeus apically with a wide impunctate margin ( Fig. 38 ). Scopa white, dark on S6 and sometimes S5, sometimes also entirely white.

Male: Very similar to Megachile rotundata although on average slightly smaller; differs from that species in the following characters: punctation on vertex less coarse, punctures similar in size to mesonotal punctures ( Fig. 39 ) (in M. rotundata , punctation on vertex coarse, punctures deeper and larger than mesonotal punctures). Punctation on mesonotum shallow, less coarse, with shiny interspaces ( Fig. 39 ); punctation on scutellum little visible (in M. rotundata , punctation on mesonotum and scutellum coarse, well-visible, without shiny interspaces). Punctation on tergites comparatively less coarse than in M. rotundata . Front tarsi with posterior fringe of hairs slightly longer than width of tarsal segments (in M. rotundata , posterior fringe of hairs shorter or at most as long as width of tarsal segments).

Figures

FIGURES 35–40. 35. Front view of head of female Megachile levistriga. 36. Front leg of male of M. levistriga. 37. Dorsal view of mesosoma and head of female of M. minutissima. 38. Front view of head of female of M. minutissima. 39. Dorsal view of mesosoma and head of male of M. minutissima. 40. Clypeus of female of M. kruegeri.