A survey of grassland Asilidae (Diptera) at Jacana Eco Estate, Hilton, South Africa
Author
Londt, Jason G. H.
KwaZulu-Natal Museum, P. Bag 9070, Pietermaritzburg, 3200, South Africa & School of Biological & Conservation Sciences, University of KwaZulu-Natal, Pietermaritzburg, South Africa
londtja@telkomsa.net
text
African Invertebrates
2020
61
1
29
48
http://dx.doi.org/10.3897/AfrInvertebr.61.50895
journal article
http://dx.doi.org/10.3897/AfrInvertebr.61.50895
2305-2562-1-29
4B0D39243E014D3A9EDCF6CBA335159F
1CCA7F4D3CB555A98C0DA976F578DA16
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 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.
Table 4.
A comparison of
Asilidae
collected at two survey sites (species listed in the order collected at Jacana Eco Estate). Jacana data taken from Table
3
and Queen Elizabeth Park data from Fig.
4
of
Londt (2002b)
. Weeks of activity calculated from both actual data and presumed occurrence when gaps in data occur. Weeks of activity (actual and presumed).
| Species |
Jacana Eco Estate |
Queen Elizabeth Park |
|
Euscelidia vallis
|
1-15, 42-52 (25 weeks) |
1-18, 41-52 (29 weeks) |
|
Ischiolobos mesotopos
|
1-6, 45-52 (14 weeks) |
1-16, 52 (17 weeks) |
|
Caenoura annulitarsis
|
5-20 (16 weeks) |
1-20, 48-52 (25 weeks) |
|
Dasophrus androclea
|
11 (1 week) |
18 (1 week) |
|
Neolophonotus wroughtoni
|
21-22 (2 weeks) |
20-36 (17 weeks) |
|
Leptogaster
sp.
|
38 (1 week) |
10-16 (7 weeks) |
|
Microstylum
sp.
|
45-52 (8 weeks) |
45-49 (5 weeks) |
|
Dasophrys fortis
|
51 (1 week) |
13 (1 week) |
|
Rhipidocephala obscurata
|
51 (1 week) |
3-5, 48-52 (8 weeks) |