Leptogaster simplex Bigot, 1878

Dikow, Torsten, 2003, Revision of the genus Euscelidia Westwood, 1850 (Diptera: Asilidae: Leptogastrinae), African Invertebrates 44 (2), pp. 1-131 : 122-128

Leptogaster simplex Bigot, 1878 , stat. rev.

Leptogaster simplex Bigot, 1878: 444 ; Hull 1962: 300.

Euscelidia simplex, Oldroyd 1975: 100 ; Joseph & Parui 1983: 278 1990: 10 1998: 19.

Type material - The ơ holotype is labelled ‘ Holotype (circular label with red submarginal border) / L. simplex ơ Ceylon J. Bigot (black submarginal border) / Type Dip: 409 Leptogaster simplex Bigot Hope Dept. Oxford (black submarginal border)’. The specimen is directly mounted, is in good condition, and is deposited in the OXUM.

Type locality: Sri Lanka, no exact locality .

Remarks: Leptogaster simplex was listed as a representative of Euscelidia in different catalogues or publications (Oldroyd 1975; Joseph & Parui 1983 1990 1998). This species does not belong to Euscelidia . The synapomorphic feature for all species of Euscelidia , the ppro peg, is not present. The pronotum is slightly excavated, but this is not homologous with the ppro peg described and illustrated above ( Fig. 3 ). Oldroyd (1972: 212) mentioned this point already, however he listed the species in the Oriental catalogue (Oldroyd 1975) as Euscelidia . Furthermore, the male terminalia have a shape never found in species of Euscelidia (sur with two equally developed lobes that are separated proximally).

Biology and ecology

Londt (1994) summarised data on the biology, ethology, and ecology of Afrotropical

Asilidae . His findings for species of Euscelidia are listed here. His observations showed that species were generally found to perch on tips of grass stalks, shrubs, bushes, and tree twigs.

Habitat grassland: species ‘… perch at tips of grass stalks and hunt in the space above the grass layer rather than within it’. He describes the simple, unspecialised ovipositor ( Figs 58D–F ) and argues that they might ‘… drop their eggs at random from perches, thus avoiding visits to the ground’.

Habitat shrubs and bushes: species ‘… perch at the tips of twigs (i.e. not leaves) on the outer “surface” of bushes’; they ‘… tend to hawk repeatedly from the same perch (i.e. they dart at prey and return with or without it to the same perch)’.

Habitat trees: species ‘… perch at the tips of dead twigs’.

The general observation that all species of Leptogastrinae live within grasslands or in bushes nearby can be exemplified by evaluating the many ecological data that are available from the specimen’s label. A short summary with examples of such ecological data summarised from the examined specimens of Euscelidia is given here: Eragrostis (Poaceae) patch; Hyperthelia (Poaceae) grass in Terminalia ( Combretaceae ) veld; Themeda (Poaceae) grassveld; Themeda triandra veld; Acacia (Mimosaceae) grassland; dense grass in Acacia veld; acacias, long grass near cattle pens; Acacia thornveld and dry river course; dry wash in Acacia -covered plain; Acacia bushveld; Acacia xanthophloea forest; acacias and low shrubs; riverine Brachystegia (Caesalpiniaceae) woodland; savannah woodland; grass and hillside Macchia; open grassland; swept on open grassland; grassland and forest margins; grassland/stream edge; grass and shrubs near river; grassland and road verges; arid grassland and bush; open grassveld area; rocky grassland; grassy hillside with rocks and bushes; rocky area bushveld long grass; rocky side of koppie, grass, trees and bush; trees and grass in poorly drained area; uplands grassveld; open hillside grass; grass under trees; bushveld with long open areas of grass; grass under or near big trees near river; mountain base grassbushveld; abundant amongst grasses surrounding lake; grass in thornveld; forest and open woodland areas; indigenous bush area; bushveld vegetation; riverine bush, montane slopes; coastal bush and forest.

Additional ecological data that were found on labels, but do not explicitly state an affinity to grasslands are for example (note: grass will certainly be present in all of these habitats, too): swept along roads in dry forest; swept in Miomboveld; Mopane woodland on rocky hillside; coast lowland forest; margins of indigenous forest; edge of montane forest; road and forest margin; swept among vegetation close to sea shore; dune forest.

Many of the specimens examined were caught in Malaise traps.

The following prey records are available for species of Euscelidia .

E. brunnea : Insecta: Hemiptera : Fulgoromorpha.

^^ of E. datis species-group: Insecta: Hemiptera : Heteroptera; Diptera : Tabanidae (several species).

E. procula: Araneae ; Insecta: Caelifera: Acrididae ; ‘Psocoptera’; Hemiptera : Fulgoromorpha; Lepidoptera ; Hymenoptera : Formicidae ; Coleoptera : Scarabaeidae ; Diptera : Tipulidae , Chironomidae , Bombyliidae , Asilidae : Damalis Fabricius, 1805 sp. , Tephritidae , Sepsidae , Tachinidae , Muscidae , Calliphoridae .

Seasonal incidence

The seasonality of all species examined is illustrated in Table 2. A distinction between 4 geographic areas was analysed to reflect the different seasons in the northern and southern hemisphere – north of 15 N; north and south of the equator to 15 N and S respectively (tropic latitudes); south of 15 S. E. procula , the most widespread Afrotropical species, appears to fly for much of the year. E. marion , mostly distributed on the island of Sri Lanka, occurs for much of the year and has only not been collected in August and December. E. bechuana , longibifida , natalensis , and notialis , restricted in their distribution to southern Africa, appear to fly during the southern hemisphere summer time, only. E. pallasii , distributed in the southern Palaearctic Region, flies during the northern hemisphere summer. Many other species have been collected only on few occasions and their true seasonal incidence cannot be reflected in the table.

TABLE 3. Comparative character matrix. Not included are Euscelidia discors , E. gutianensis , and E. zumpti because no specimens have been examined. Species are arranged alphabetically within the zoogeographical Region they occur in.

Comparative character matrix ( Table 3)

This matrix is provided to assist in identifying species with the help of diagnostic features and supplements the identification key. Not included are discors , gutianensis , and zumpti because no specimens have been examined.

List of characters:

I. Number of setae comprising mystax - (0) few, usually less than 12; (1) many, usually more than 20.

II. Development of pruinosity on sct - (0) entirely covered with pruinosity; (1) predominantly pruinose, but longitudinal median stripes and/or lateral spots apruinose; (2) predominantly apruinose, pruinosity restricted to anterior, lateral, and posterior margins.

III. Development of setae on posterior sct - (0) only few, short setae present; (1) many, long setae present.

IV. Length of emp - (0) minute, indistinct; (1) very short, distinct; (2) long, from a fifth to nearly the length of a clw.

V. Development of microtrichia in cell d - (0) no or only few microtrichia; (1) densely covered with microtrichia.

VI. Transparency of wing - (0) hyaline; (1) opaque (brown coloured).

VII. Development of dorsal pruinosity on abdominal tergites - (0) all T entirely covered with pruinosity; (1) T2 with apruinose spot anteriorly; (2) T2–3 with apruinose spots anteriorly; (3) T2–4 with apruinose spots anteriorly; (4) T2–5 with apruinose spots anteriorly; (5) T2–7 with apruinose spots anteriorly.

VIII. Shape of ventral margin of sur (lateral view) - (0) straight, no lobe; (1) distinct lobe of variable shape present.

IX. Shape of dorsal tip of sur (lateral view) - (0) dorsal tip broad, blunt; (1) dorsal tip pointed.

X. Length of d aed shea - (0) short; (1) medium; (2) long (extending hypopygium).

List of valid species:

Afrotropical Region (55 species) - acuminata , adusta , anthrax , artaphernes , atrata , bechuana , bequaerti , bicolor , bishariensis *, brunnea , cacula , cana , capensis , castanea , crena , datis , discors , dorata , erichthenii , fastigium , festiva , fistula, francoisi , hesperia , hyalina , insolita , kasungu , lata , longibifida , lucida , lucioides , milva , moyoensis , mucronata , natalensis, nenemusha , nitida *, notialis , obtusa , obudu, ochricornis , peteraxi , picta , pipinna , procula , pulchra , rapax , schoutedeni , senegalensis , trifoliata , tsavo , valida , vallis , venusta , zumpti .

Oriental Region (11 species) - abbreviata , cobice , flava , glabra , lepida , livida , marion , popa , prolata , rapacoides , splendida .

Palaearctic Region (4 species) - bishariensis *, gutianensis , nitida *, pallasii .

* E. bishariensis and nitida are probably distributed in both the Afrotropical and Palaearctic regions.

NOTE ADDED AFTER COMPLETION OF PAGE-LAYOUT

Five specimens collected in Sri Lanka and deposited in the USNM collection were examined while this revision was already in press. They represent two undescribed species of which only the locality data and date of collection will be provided: Species I – 1_ Kala-Oya, 1.viii.1975; Species II – 1^ 1ơ Ma Villu, Cashew Corp., 17-21.ii.1979; 1^ Angunakolapelessa, 24-26.ix.1977; 1^ Wilpatta National Park, 5-8.x.1977.

Figures

Fig. 3. Euscelidia senegalensis sp. n. Lateral aspect of head and thorax (not all setae illustrated). Scale line = 1 mm.

Fig. 58. ^ and ơ terminalia. A–G. Euscelidia pulchra sp. n. A. ơ dorsal. B. ơ ventral. C. ơ lateral. D.^ dorsal. E. ^ ventral. F. ^ lateral. G. Aedeagus lateral. H–M. E. senegalensis sp. n. H. Aedeagus lateral. I. Lateral apodeme posterior. K. Dorsal. L. Ventral. M. Lateral. Scale lines = 1 mm.