Euscelidia vallis Dikow, 2003

Londt, Jason G. H., 2020, A survey of grassland Asilidae (Diptera) at Jacana Eco Estate, Hilton, South Africa, African Invertebrates 61 (1), pp. 29-48 : 29

1. Euscelidia vallis Dikow, 2003 Fig. 9

Remarks.

This species was positively identified by Dikow (pers com) who reviewed the extensive Afrotropical Euscelidia fauna, comprising over fifty species ( Dikow 2003). The species was described, based on only three specimens, two from Mhlopeni Nature Reserve (29°00'S, 30°25'E), collected in February and one from Van Reenen (28°22'S, 29°23'E) collected in January.

Adults of this species were encountered in large numbers on the first sampling day and the species remained abundant for the following 11 weeks before numbers began to decrease from week 12. The species was poorly represented during weeks 13-15, before finally disappearing in week 16. The species was not collected throughout winter and most of spring, but reappeared in moderate numbers on week 42. The species was fairly common during weeks 42-47, before again being fairly abundant on week 48. For some unknown reason, the species suddenly disappeared from samples taken during weeks 49 and 50 before reappearing in low numbers on week 51 and in greater numbers on week 52. This species was, without doubt, the most commonly encountered species, especially in the upper field, during the survey, being present for some 26 weeks of the year.

This small species was invariably swept from long grass with very few actually being sighted. None were encountered mating or with prey. The species appears to be largely confined to Londt’s (1994) ecological category 4a (within grass).

Material from Jacana has been compared with specimens collected during the Queen Elizabeth Park survey ( Londt 2002b) and found to be conspecific. Table 4 provides a comparison of flight periods with those recorded from Queen Elizabeth Park. Adults were encountered at approximately the same time of year and flight periods ranged from 25 weeks at Jacana to 29 weeks at Queen Elizabeth Park.

Figures

Figures 4 - 13. Grassland inhabiting Asilidae encountered at Jacana Eco Estate (arranged alphabetically): 4 Caenoura annulitarsis (Loew, 1858) 5 Damalis monochaetes Londt, 1989 6 Dasophrys fortis Londt, 1981 7 Dasophrys tarsalis (Ricardo, 1920) 8 Dysclytus firmatus (Walker, 1857) 9 Euscelidia vallis Dikow, 2003 10 Ischiolobos mesotopos Londt, 2005 11 Leptogaster sp. 12 Microstylum sp. 13 Rhipidocephala obscurata Oldroyd, 1966. Photos: B. Muller.