Edenophorus stuckenbergi, Sinclair, 2002

Sinclair, Bradley J., 2002, Revision of the South African endemic genus Edenophorus Smith (Diptera: Empididae), African Invertebrates 43, pp. 109-122 : 120-122

Edenophorus stuckenbergi sp. n.

( Fig. 10 )

Etymology: Named in honour of the collector, Brian R. Stuckenberg, who has collected innumerable other new taxa from South Africa.

Holotype male labelled: SOUTH AFRICA: Western Cape: ‘ Sevenweekspoort / Laingsburg Dist / West. Cape Prov / 19–22 Sept 1959 / B. & P. Stuckenberg [head, left wing missing] [all caps]’ ( NMSA).

Recognition: This species is distinguished by the absence of cell dm, pale legs, and male terminalia with sharp, blade-like setae arising from the cerci, and with the epandrial lobe strongly bent at mid-length.

Description:

Male:

Head: Missing in holotype.

Thorax: Dusted entirely with grey pruinescence. Thoracic setae generally short, slender, pale, reduced to numerous rows: Acr biserial; at least 9 dc, uniserial, gradually increasing in length posteriorly with prescutellar dc stout, similar to pprn; inter-alar setulae scattered, extending to wing base; 2 pprn (lower directed anteriorly, upper directed dorsomedially) and several short setulae; 1 ph; 3 npl, upper shortest; 1 pal; 4 sctl, inner pair stouter and twice length of outer pair. Antepronotum with 2 pairs of short, pale setae; upper half of anepisternum obscured by pin; precoxal bridge with 2 setae above fore coxa.

Legs: Pale yellow (concolorous with halter), apical tarsomeres darker. Fore coxa with with several stout, long, lateral pale setae; segments clothed in fine pale setulae, lacking modified setae.

Wings (length 1.6 mm): Stigma indistinct. Venation similar to other species, except crossvein dm-cu absent; M vein reduced in strength, medial fork U-shaped, petiole or stem slightly shorter than fork; M 1 not strongly arched towards wing margin, nearly parallel with R 4+5. Halter yellow.

Abdomen: Lightly dusted greyish brown, concolorous with scutum. T8 broad, one-half length of preceding tergite; S8 divided into pair of rounded, lateral sclerites, not articulated with T7.

Terminalia ( Fig. 10 ): Held upright, cercus anterior; partially retracted into segment 8. Cercus thickly sclerotised, with 3 stout apical setae and posterior row of 4 blade-like, pointed setae. Epandrium with finger-like lobe projected dorsally, sharply bent at mid-length. Hypandrium reduced to series of slender sclerites; hypandrial bridge broad, with greatly expanded, horizontally projected gonocoxal apodemes. Phallus with enlarged basal sperm chamber; ejaculatory apodeme inverted Y-shaped, broad, stout, articulated at base of chamber, subequal to onehalf length of terminalia. Postgonite tapered to small rounded apex, extended ventrally to near base of phallus.

Female: Uncertain (see Remarks).

Additional material examined: SOUTH AFRICA: Northern Cape: 1 female, Nieuwoudtville Area, Calvinia District , 14.x.1964, B.& P. Stuckenberg ( NMSA) .

Remarks: The female specimen is not included in the type series, although it is possibly conspecific based on the wing venation. A male from this locality would help to clarify the identity of this specimen.

ZOOGEOGRAPHY

Distribution

Although based on very few records, this genus exhibits a common empidoid distribution in South Africa. It is primarily confined to east and south of the Great Escarpment, and to the Cape Fold Belt ( Fig. 11 ). Similar patterns are also illustrated in Smith (1969) and Sinclair (1996).

The genus occurs in two widely separated areas, though this may be a collecting artefact. The two species in KwaZulu-Natal were found at the same place, and in midwinter (June/July), when collecting of Diptera is not normally undertaken. The locality has been visited frequently over many years in spring and summer by numerous Diptera collectors.

The two known localities for E. knysna are damp sites within indigenous forests. The other species of the SW Cape come from completely different habitats. Both E. spinosus and E. nigricans were found in the Pakhuis section of the Cederberg Range, an area with a rich Fynbos montane shrubland flora and no forest. Edenophorus stuckenbergi was also from montane sites with Fynbos. The dipteran fauna of Fynbos is rich in endemics, and the influence of the winter-rainfall regime is marked, with most of the insect fauna emerging in early spring when the flora comes into flower (Stuckenberg, pers. comm.). The type locality of E. simplex in southern Namaqualand is very different. This locality is in a highly distinctive region known as the Knersvlakte. It is an arid terrain of sandy flats and low, rounded hills; rainfall usually is less than 150 mm per annum, and the flora is low, shrubby, and dominated by succulents with a very high level of endemicity.Although the type locality was stated to be at the confluence of two rivers, these in fact are dry sandy watercourses that rarely and then only briefly have water in them (Stuckenberg, pers. comm.).

Gondwanan taxon

The rarity of Edenophorus , with only 14 specimens obtained in over 40 years of intensive collecting of flies in many parts of South Africa, suggests small, highly localised populations, with the adult stage limited to brief periods. Nevertheless, the mid-winter presence of adults in the Karkloof suggests a relict status. This scenario is similar to the apparently gondwanan rhagionid genus Atherimorpha White , in which some species have been found only in winter, including one collected by the author together with E. hiemalis .

On the basis of the above discussion, and given its proposed sister-group relationship with the clade Empidadelpha + Empidini + Hilarini (see Phylogenetic relationships), Edenophorus should be classified as a gondwanan element. It is unrelated to any other African or palearctic Empidinae , and Empidadelpha is presently known only from Chile, New Zealand and Australia.

Figures

Figs 8–10. Edenophorus male terminalia, lateral view. 8. E. hiemalis sp. n. 9. E. simplex sp. n. 10. E. stuckenbergi sp. n. Sclerites of segment 8 marked by dashed outline (not shown in Fig. 9). Scale bar = 0.1 mm. [Abbreviations: cerc = cercus; ej apod = ejaculatory apodeme; epand = epandrium; epand lb = epandrial lobe; goncx apod = gonocoxal apodeme; pgt = postgonite; ph = phallus; sp ch = sperm chamber.]

Fig. 11. Known distribution of species of Edenophorus. = E. hiemalis sp. n., = E. irwini sp. n., • = E. knysna Smith, = E. nigricans sp. n., = E. simplex sp. n.,! = E. spinosus sp. n, = E. stuckenbergi sp. n.