Megastigmus icipeensis Roques & Copeland

Roques, Alain, Copeland, Robert S., Soldati, Laurent, Denux, Olivier & Auger-Rozenberg, Marie-Anne, 2016, Megastigmus seed chalcids (Hymenoptera, Torymidae) radiated much more on Angiosperms than previously considered. I- Description of 8 new species from Kenya, with a key to the females of Eastern and Southern Africa, ZooKeys 585, pp. 51-124 : 81-84

Taxon classification Animalia Hymenoptera Torymidae

Megastigmus icipeensis Roques & Copeland sp. n.

Type material.

Holotype ♀, Kenya, Nairobi Province, ICIPE Campus, Kasarani, 1.2232°S, 36.8965°E, 1600m elevation, Malaise trap, meadow in degraded shrub-/grassland, 24 Feb to 3 Mar 2014, R. Copeland leg. (NMKE)

Paratypes 4♀♀, the same as holotype (1♀ NMKE; 1♀ RSC; 1♀ ARC; 1♀ ICIPE).

Additional material.

3♂♂, collected together with the four females (2♂♂ RSC; 1♂ ARC).

Description.

Holotype ♀. Very small species with body length (without ovipositor) 1.2 mm; length of ovipositor sheaths 0.9mm. Body colour nearly entirely orange- yellow (Figures 62-64). Head colour orange, except mouthparts brown (Figure 65). Pilosity on lower face pale; dorsum of head with conspicuous black hairs: a row along the internal side of each eye from parascrobal area to temple, a row along the occiput, and three isolated hairs around each of the lateral ocelli; two interocellar bristles. Antenna dark- brown except scape and pedicel yellow underneath (Figure 66). Thorax entirely orange except a small black spot on axilla at wing insertions and on lateral panel of metanotum (Figure 64). Pilosity on thorax mostly pale; sparse long hairs on pronotum, especially along the suture with mid-lobe of mesoscutum; 3 pairs of pale hairs on the lateral side of mid-lobe of mesoscutum, very close to suture with the lateral lobe; 2 pairs of pale hairs on scutellum. Legs entirely pale yellow except claws brown; Forewing stigma brown without infuscation; basal cell without setae, closed by a basal setal line with 5 setae and a costal setal line with 3 setae (Figure 67). Propodeum orange with a transverse black stripe along the suture with metanotum (Figure 64). Propodeum hairs pale; Gaster orange, with four large transverse orange-brown bands along the anterior sutures of the tergites 4-8; pilosity on gaster black. Ovipositor sheaths black, 1.6 × longer than gaster, 0.7 × as long as body (Figure 63).

Head about 1.2 × as wide as long in front view (Figure 65). POL large, POL: OOL: 2.7. Scape 1.1 × as long as combined length of pedicel, anellus, and F1 (Figure 66); scape 0.9 × as long as combined length of pedicel, anellus, F1 and F2; pedicel elongate, 1.5 × longer than F1; F2 subquadrate, small, 0.8 × as long as F1; following funicular segments subquadrate from F2. Pronotum, mid-lobe of mesoscutum, axilla and scutellum with fine transverse striae. Mid-lobe of mesoscutum conspicuously short, only 0.9 × as long as scutellum length; scutellum 1.1 × as long as wide; frenum roughly 0.4 × as long as scutellum length, with the same sculpture as the remainder of scutellum. Propodeum with a zig-zag median carina. Forewing stigma oval, without infuscation, about 1.4 × as long as wide (Figure 67); upper part of stigmal vein short, 0.2 × as long as stigma length; uncus as long as upper part of stigmal vein; marginal vein 0.8 × as long as postmarginal vein.

Variation. Body ranges 1.2-1.3 mm with ovipositor up to 1.2 mm. Ovipositor length varies from 0.7 to 0.9 × the body length, and from 1.6 to 2.0 × the gaster length. No variation in colour and pilosity.

Male. In the absence of molecular analyses, the males caught in Malaise traps along with the four female Megastigmus icipeensis could not be attributed with certainty to this species but noticeable convergences in morphology make it probable. Body length 1mm. Same body colour as in female of Megastigmus icipeensis (Figures 68-70) except a paler yellow pronotum and some additional black patterns on head and thorax: an irregular spot surrounding the three ocelli, an annelation at insertion of pronotum, a darkening of the lateral sutures of mid-lobe of mesoscutum, a narrow transverse band on lateral panel of metanotum, and a transverse band covering the base of propodeum and extending in its middle into a large longitudinal spot in shape of inverted Y (Figures 62, 64). Gaster petiolate, mostly brown- black on dorsum: T3 black, T4 brown black with a large transverse yellow band distally, T5 similar but the yellow band narrower, T6 brown-black, T7 yellow.

Legs yellow with the two last tarsal segments and claws black. Pilosity pale on head and thorax, showing the same setal pattern as in female Megastigmus icipeensis , including the interocellar brisles and 2 pairs of pale hairs on scutellum (Figure 70). Forewing stigma without infuscation (Figure 73); basal cell closed, but without setae on disc; basal setal line with 6 setae, costal setal line with 3 long setae; costal cell with only 3 small setae in the apical 1/2 to 2/3.

Head transverse, about 1.3 × as wide as long in front view (Figure 71). OOL short, POL: OOL: 2.8. Scape 1.2 × as long as combined length of pedicel, anellus, and F1 (Figure 72); scape as long as combined length of pedicel, anellus, F1 and F2; pedicel elongate, 1.8 × longer than F1; F2 subquadrate, small, 0.8 × as long as F1; following funicular segments also subquadrate. Pronotum, mid-lobe of mesoscutum, axilla and scutellum finely transversely striated. Mid-lobe of mesoscutum conspicuously short, only as long as scutellum length; scutellum 1.1 × as long as wide; frenum roughly 0.4 × as long as scutellum length, with the same sculpture as the rest of scutellum. Propodeum with an irregular median carina. Forewing stigma nearly rounded, only 1.3 × as long as wide (Figure 74); upper part of stigmal vein very short, only 0.2 × as long as stigma length; uncus 1.5 × longer than upper part of stigmal vein; marginal vein 1.1 × longer than postmarginal vein. Genital digitus with only 2 teeth (Figure 73).

Host plants.

Unknown. In the molecular study, Megastigmus icipeensis did not group with other taxa, but the phylogenetic position (Figure 14) and the genetic distances between this species and the other groups led to suggest that it could be a seed-feeder associated with another plant family than those identified in this paper.

Distribution.

Only known from the collection site in a degraded meadow near a small stream.

Etymology.

Named after the institution on whose grounds the species was collected, the campus of the International Centre of Insect Physiology and Ecology (ICIPE), Nairobi.

Diagnosis.

The species can be easily distinguished from other tiny Megastigmus spp. known from the Afrotropical region by the pale bristles on the thoracic dorsum whereas they are mostly black in Megastigmus zebrinus (Grissell, 2006), and by its orange body whereas Megastigmus pretorianensis is mostly black with brown areas ( Doǧanlar 2015). In contrast to most other species, the male genital digitus bears only two teeth such as in Megastigmus helinae but the phallobase of the latter species is more elongate (Figure 29).