Bembecinus zebratus R. Bohart

Gess, Friedrich W., Pulawski, Wojciech J. & Gess, Sarah K., 2015, A Revision of the rhopalocerus Species Group of Bembecinus Costa (Hymenoptera: Crabronidae: Bembicinae), Proceedings of the California Academy of Sciences 62 (7), pp. 207-256 : 243-245

Bembecinus zebratus R. Bohart

Figures 5e , 23.

Bembecinus zebratus R. Bohart, 1997:171 , Fig. 7, ♀, ♂. Holotype: ♂, South Africa: Western Cape Province: Worcester ( UCDC according to original description, but apparently lost). Neotype: ♂, South Africa: Western Cape Province: Worcester, paratype of B. zebratus (UCDC) designated by W. Pulawski.— Pulawski, 2014:44 (in catalog of world Sphecidae sensu lato).

RECOGNITION.— Bembecinus zebratus has the scutum all black mesally, and terga black, not ferruginous, with narrow, yellow apical fasciae. It differs from damarensis in having tergum I mostly black except for the narrow, yellow apical fascia, the dorsal margin of the female forefemur practically straight and the ventral margin not expanded basally, the apical flagellomere of the male only slightly curved and excavated (Fig. 23a), and tergum VII is short, trapezoid (Fig. 23b). In damarensis , the dorsal surface of tergum I is yellow except for the median, black, nearly rectangular marking that does not attain posterior margin ( Fig. 6b ), the female forefemur is somewhat concave basally and the ventral margin is slightly expanded basally ( Fig. 6a ), the apical flagellomere of male is markedly curved and excavated, and tergum VII is significantly longer, roundly triangular ( Fig. 6d ).

Differences between zebratus and pakhuisae are slight. In the female of zebratus , the clypeus is all FIGURE 23. Bembecinus zebratus : a – apical flayellow and the mesopleuron has a vertical yellow gellomeres of male, b – male tergum VII. marking (yellow marking present or absent in the male); in most males, the apical flagellomere is slightly more curved and excavated (Fig. 23a) than in pakhuisae , but about the same in the specimen from Niewoudtville, and the yellow, apical fasciae on the terga are markedly narrower (e.g., the fascia of tergum II is markedly shorter than the black, anterior portion). In the female of pakhuisae , the clypeus is all or partly black and the mesopleuron is all black (as it is in the male); in the male, the apical flagellomere is slightly less curved and excavated (Fig. 17b), and the yellow apical fasciae on terga are markedly broader (e.g., the fascia of tergum II is slightly shorter to longer than the black, anterior portion).

DESIGNATION OF NEOTYPE.— The holotype of Bembecinus zebratus was deposited in UCDC according to the original description, but Steven L.Heydon, Senior Museum Scientist, could not find it there, neither in the type collection nor in the general collection. Apparently, the holotype has been lost, and W. Pulawski designated as a neotype one of the existing paratypes, a male.

MATERIAL EXAMINED.— SOUTH AFRICA: Northern Cape: Niewoudtville Flower Reserve , 24.ix.2006, K. Timmermann (1 ♂, BMNH) . Western Cape Province: Worcester, ix-x.1931, R.E. Turner (1 ♀, BMNH); Worcester , x.1975, R.M. Bohart (9 ♀, 13 ♂, UCDC, neotype and paratypes of zebratus ) .

GEOGRAPHICAL DISTRIBUTION.— Known from the winter rainfall area of South Africa from one locality in southeastern Namaqualand and one in the Western Cape Province of South Africa ( Fig. 26e ).

FLORAL ASSOCIATIONS.— Unknown.

NESTING.— Unknown.

PREY.— Unknown.

DISCUSSION OF GEOGRAPHICAL DISTRIBUTIONS, FLORAL ASSOCIATIONS, NESTING, AND PREY

The distribution records here assembled for the Bembecinus rhopalocerus species group ( Figs. 24–26 ) make possible the recognition of geographical patterns for some species; for others, however, the number of records remains too few, drawing attention to species, which require purposeful collecting.

Current knowledge of the distributions of the species suggests that most are restricted to southern Africa and within southern Africa to the semi-arid to arid Succulent Karoo and Nama-Karoo ( Fig. 26f ). Three species ( gilvus , omaruru and quadristrigatus ) penetrate the Namib Desert along the courses of drainage channels and one ( somalicus ) is known only from Ethiopia, Kenya, and northeast Tanzania.

Bembecinus visit plants not only to obtain nectar for adult nourishment but also when hunting their Homoptera prey. Records of actual visits to flowers by members of the rhopalocerus species group are surprisingly few. Records are for 11 families: Asteraceae , Zygophyllaceae , Amaranthaceae , Molluginaceae , Fabaceae , Neuradaceae , Aizoaceae (Mesembryanthema and non-Mesembryanthema), Boraginaceae , Campanulaceae , Pedaliaceae and Vahliaceae . Most commonly the flowers visited are small and grouped in heads, as are those of the first four families listed.

Typically, the species of Bembecinus have the female foretarsus equipped with long sand-rakes, and excavate sloping nesting burrows in friable soil. The only known exceptions are two species of the cinguliger species group ( cinguliger and oxydorcus ) which lack sand-rakes and use water for excavating vertical burrows in non-friable soil (F. Gess and S. Gess 1975; F. Gess 1981; S. Gess and F. Gess 2014). Nesting has been documented for only four species of the rhopalocerus group: hyperocrus , mutabilis , pakhuisae , and rhopalocerus , but all species of this group have sand-rakes and therefore undoubtedly nest in sloping burrows excavated in friable soil.

Prey records are available for only the above four species of the rhopalocerus group. These are all Homoptera of the families Cicadellidae , Issidae , Nogodinidae and Flatidae .

Figures

FIGURE 5. Bembecinus spp.: a – quadristrigatus, female, male; b – rhopaloceroides, female, male; c – rhopalocerus, female, male; d – somalicus, female, male; e – zebratus, female, male (approximate lengths of females: a. 11.5 mm, b. 11.5 mm, c. 13 mm, d. 11.8 mm, f. 10.5 mm).

FIGURE 6. Bembecinus damarensis: a – female forefemur, b – female tergum I showing color pattern, c – apical flagellomere of male, d – male tergum VII.

FIGURE 26. Collecting records of Bembecinus spp.: a – quadristrigatus, b – rhopaloceroides, c – rhopalocerus, d – somalicus, e – zebratus, f – all species combined.

FIGURE 24. Collecting records of Bembecinus spp.: a – damarensis, b – gariepensis, c – gilvus, d – helicicola, e – hyperocrus, f – inexpectatus.

FIGURE 25. Collecting records of Bembecinus spp.: a – karasanus, b – mutabilis, c – namaquensis, d – namibius, e – omaruru, f – pakhuisae.