Oligoneuriopsis elisabethae Agnew, 1973

Barber-James, Helen M., Zrelli, Sonia, Yanai, Zohar & Sartori, Michel, 2020, A reassessment of the genus Oligoneuriopsis Crass, 1947 (Ephemeroptera, Oligoneuriidae, Oligoneuriellini), ZooKeys 985, pp. 15-47 : 15

Oligoneuriopsis elisabethae Agnew, 1973 Figure 8

Oligoneuriopsis elisabethae Agnew, 1973: 118, fig. 1C (nymph).

Material examined.

Lesotho • 4N; Tsoelikana River; 29.9200°S, 29.0925°E; alt. 2247 m a.s.l.; 21 Jan. 1986; K. Meyer; AMGS; LES 38U • South Africa • 4N; KwaZulu-Natal, Umkomozana River, Sani Pass; 29.5842°S, 29.2883°E; alt. 2870 m a.s.l.; 14 Jan. 2011; T.A. Bellingan; AMGS; GEN 1978C.

Comments.

As with O. jessicae , the material examined by Agnew has been lost. This includes VAL 606G Klip River, Vrede-Volksrust Rd. Bridge 1959/01/14 27.35806°S, 29.35000°E, Free State Province, and VAL 1061B, VAL 1062A. Klein Vaal R., at Goedehoop Farm 1960/03/22 26.8194°S, 30.1333°E, Mpumalanga Province, F.M. Chutter leg. As the material examined is from a different catchment to the type material, no neotype has been designated.

Male and female imagos.

Unknown.

Nymph.

Lengths. Body up to 16.5 mm ( Agnew 1973), sex-based size differences of nymphs not recorded as none of the available material is fully mature. Cerci up to 8.1 mm, caudal filament 3.3 mm. General colouration light brown (Fig. 8A ). Head (Fig. 8A ) light brown, with darker brown marking between bases of antennae and ocelli and a grey-brown maculation between antennae; carina on frons slightly developed. Ventrally, head a uniform light brown colour; gills at base of maxillae forming a “beard” ventrally at base of head, much paler in colour relative to head capsule (Fig. 8B ). Pro and mesonotum pale brown, with darker maculae laterally. Legs light brown, femoro-tibial articulation with a blackish spot. Femur and tibia of foreleg shorter than those of mid or hind leg; femora and tibiae of mid and hid legs of approximately equal length. Setae on the outer margin of mid and hind femora well developed, evenly distributed along length of margin; mid and hind tibiae and tarsi with well-developed fringe of even setae along the outer margin. Middle and hind legs with basal area of coxae and trochanter, and entire surface of femora covered with small, scattered, dark brown spine-like setae, extending also along ventral margins of tibiae and tarsi, as well as interspersed amongst the fringe of setae along the dorsal margins.

Abdominal tergites uniformly pale brown, no distinctive patterns except for paired pale cream-coloured markings forming a V-shaped pattern on last three abdominal segments in some specimens (Fig. 8A ). Sternites uniform pale brown, with no distinctive markings (Fig. 8B ). Dense patch of posteriorly orientated setae ventromedially moderately developed on abdominal sternite II, well-developed on sternites III-V, absent from other segments. Gills paler in colour than abdomen, gill I ventrally orientated, lamella less than one third the length of the fibrillar portion, gills II-VII with rounded lamella, filaments shorter than the corresponding lamella, lamella shorter than half the length of the corresponding segment. Lamellae II-VII with long and thin setae on their distal inner margin. Posterolateral spines of the abdomen of similar size on each segment, each with the tip a darker brown. Cerci uniformly medium brown, caudal filament paler brown towards apex, less than half the length of cerci.

Affinities.

Nymphs of O. elisabethae are less flattened compared to O. lawrencei , and have the shortest gills relative to the abdominal tergite length of the three South African species, at ca. 1/3 of the length of the tergites. Head similar in shape to O. jessicae but notably different to O. lawrencei , which is widest medially. Lateral abdominal spines are well developed; dorsal abdominal spines as seen in O. jessicae are absent in O. elisabethae. Nymphs of O. elisabethae also differ from those of O. skhounate , O. dobbsi , O. orontensis and O. villosus by the reduction of the caudal filament.

Habitat preference.

Found in cobble, pebble and gravel substrate in swift current.

Known distribution.

Lesotho; South Africa: Free State and Mpumalanga Provinces.

Figures

Figure 8. Oligoneuriopsis elisabethae A whole nymph (immature), dorsal view B dorsal view of head. Scale bar: 5 mm (A).