Hylaeus (Alfkenylaeus) arnoldi ( FRIESE, 1913 ), 2015

Dathe, Holger H., 2015, Studies on the systematics and taxonomy of the genus Hylaeus F. (9) Supplement to the taxonomy and distribution of Afrotropical Hylaeus F. species (Hymenoptera: Anthophila, Colletidae), Beiträge Zur Entomologie = Contributions to Entomology 65 (1), pp. 9-26 : 13

Hylaeus (Alfkenylaeus) arnoldi ( FRIESE, 1913)

Hylaeus arnoldi should also be included (or remain) in the subgenus Alfkenylaeus , although the male terminalia partly constitute special structures (S8). Snelling himself (1985: 18 ff.) ran this species in his determination key to Hylaeus (Alfkenylaeus) . He treated it as a separate subgenus, but could not reach a final decision on the basis of his data.

In H. arnoldi , the gonoforcipes of the male genital capsule are significantly extended, but not shaped like narrow styli. Sterna 7 and 8 are independent formations sui generis, but at least in the case of S7 are imaginable as a transitional form: the apical part can be interpreted as a ridge, the basal part as a lamella, as they appear in the other species of the group. The lobes of S8 are special structures without direct equivalents. A number of not insignificant characters seem to contradict these controversial findings. The species appear very close to each other: the sculpture of head, meso- and metasoma is smooth and shiny, the punctation strenght is strong to coarse, the pilosity is striking, white and erect, the propodeum is regularly domed just as in the other H. ( Alfkenylaeus ) species. SNELLING (1985: 13) outlines a number of features of the occipital edge, the pronotum, the mesepisterna, the gradulus, etc. In the males, the supraclypeal area is clearly set off from the frons surface, and the face drawings of females immediately remind one of H. ( Alfkenylaeus ) species, except that they differ clearly in the punctation of basal terga 1 and 2. In both sexes, the base of T1 shows a pronounced rimmed triangular impression as in H. acariphorus . However, definitive information on the taxonomic distance can probably only be provided by a DNA analysis. Until then I do not see a reason to keep H. arnoldi separate. MICHENER (2000: 194, 2007: 203) discussed the problems and reached a similar conclusion.

Distribution: Namibia, Zimbabwe ( EARDLEY & URBAN 2010: 27); new to Botswana, Kenya and Mozambique.

New records: Botswana: North of Maun , Island Sateri 01.– 31.01.1997 ,

1 ♂, M. Snižek lg. – In coll. SDEI. Kenya: Mpala Research Centre , 10.06.1999 , 3 ♀, on

Acacia gerrardii, G.N. Stone lg. – In coll. SANC, SDEI. Mozambique: Manicata pr., 70 km SE Chimoio, 23–

24.12.2003, 1 ♂ 1 ♀, J. Halada lg. – In coll. OLBL .