Megastigmus lanneae 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 : 90-93

Taxon classification Animalia Hymenoptera Torymidae

Megastigmus lanneae Roques & Copeland sp. n.

Type material.

Holotype ♀: Kenya, Eastern Province, Machakos, 1.5609°S, 37.2338°E, 1586m elevation, 3 May 2005, ex. Lannea rivae fruits, Coll. N°3109, R. Copeland leg. (NMKE)

Paratypes 8♀♀, 12♂♂, same collection data as holotype (2♀♀, 2♂♂ NMKE; 2♀♀, 4♂♂ RSC; 2♀♀, 2♂♂ ARC; 1♀, 2♂♂ ICIPE; 1♀, 2♂♂ SAMC);

Additional material in alcohol.

Kenya; 7 ♀♀ same collection data as holotype; 2♀♀, same collection data as holotype except 25 Nov. 2004, ex. Lannea rivae seeds, Coll. N°3042, R. Copeland leg. (ARC).

Description.

Holotype ♀. Large species, body length (without ovipositor) 5.4 mm; length of ovipositor sheaths 4.2 mm. Body colour yellow and brownish (Figures 96-98). Head yellow with the following dark patterns (Figure 99): a brownish band from frons to occiput, covering the interocellar area, base of eye at malar line black, malar line with a brownish infuscation, temple with a brownish infuscation. Pilosity on face and gena pale, dark hairs on temple, vertex and parascrobal area (Figure 99). Antenna light brownish, scape and pedicel yellow underneath (Figure 100). Pronotum yellow with a large, nearly rectangular, dark median band extending from anterior to posterior suture (Figure 98); mid-lobe of mesoscutum with a large triangular band covering most of the surface, narrowing from anterior to posterior, its colour turning progressively from brown-red to dark brownish; lateral lobe of mesoscutum with a large orange rectangular band on the antero-lateral corner continuing as a smaller grey band; axilla with an orange band at apex; lateral and ventral sides entirely yellow except two blackish spots at wing insertion; scutellum with a large triangular dark-brownish band, covering about half of the surface until reaching the frenum; frenal area nearly completely dark brownish, with a narrow yellow band on sides; lateral panel of metanotum with a narrow brownish band. Pilosity on thorax dark with long hairs on the yellow parts of pronotum, mid-lobe of mesoscutum (eight pairs of long hairs), lateral lobe of mesoscutum (three rows of hairs of different sizes), and scutellum (four lateral pairs, one on them on the frenum). Legs yellow except claws brown; fore femora with several long black hairs at apex, hind femora with numerous pale hairs; tibiae with 3 rows of long black hairs. Forewing stigma brown, without infuscation; basal cell closure poorly defined, with 9 small setae on disc; only 1 seta on basal setal line; 4 small setae on costal line; costal cell with 4 large setae (Figure 101). Propodeum with a large black rectangular band in its middle, and a brownish spot around spiracle. Gaster with a narrow, yellow longitudinal median band (Figure 96); T3 dark orange, T4 with a dark brown triangular spot extending from the median yellow line to the side of the tergite, continuing as an orange- brown band, thus delimiting a triangular yellow cell closed laterally by a comma- shaped blackish spot; lateral parts of gaster whitish. Ovipositor sheaths black, 1.8 × longer than gaster, 0.7 × as long as body (Figure 97).

Face quadrate, width: height ratio: 1.0 (Figure 99); POL: OOL 1.7; scrobe elongate, ca. 4.2 × as long as wide. Scape 1.1 × as long as combined length of pedicel, anellus and F1 (Figure 100); scape 0.8 × as long as combined length of pedicel, anellus, F1 and F2; anellus subquadrate; F1 1.2 × longer than pedicel, 1.7 × as long as wide; F2 1.9 × as long as wide; following funicular segments progressively tending to subquadrate, with F7 1.2 × as long as wide. Pronotum, mid- and lateral lobes of mesoscutum, and axilla with coarse transverse cross- striae. Mid-lobe of mesoscutum 1.5 × as long as scutellum length. Scutellum 0.9 × as long as wide, with reticulate striation; frenum 0.4 × as long as scutellum, with reticulate striation in the middle, and carinae laterally. Stigma oval- elongate, about 1.5 × as long as wide (Figure 101); upper part of stigmal vein elongate, 0.5 × as long as stigma length; uncus 0.7 × as long as upper part of stigmal vein; marginal vein 0.9 × as long as postmarginal vein. Propodeum with coarse transverse striae.

Variation. Length of female body varies from 4.8 to 5.4 mm. The relative length of the ovipositor sheaths varies between 1.6 and 1.8 × the gaster length, and between 0.6 and 0.7 × the body length. In three out of the eleven specimens examined, the brownish bands on thorax and abdomen are closer to to dark orange, becoming less distinct. One specimen, with two setae on the basal setal line, a second specimen with four setae.

Males. Like in most other Megastigmus species related to Anacardiaceae , males are highly variable in colour, and two extreme forms can be distinguished with intermediates.

Pale form. Body length from 4.2 to 6.2 mm. Body colour mostly orange-yellow (Figures 102-104). Head orange with a blackish ring around occiput. Pilosity on lower face pale but conspicuous black hairs on parascrobal area, temple, gena and dorsum of head. Antenna yellow. Thorax orange-yellow except a small black spot at wing insertion and a more or less distinct median longitudinal band of darker orange colour extending such as in female from anterior suture of pronotum to scutellum. Pilosity on thorax black with 4 pairs of long setae on scutellum (Figure 104). Legs entirely yellow; pilosity pale on femurs, black on tibiae. Forewing stigma brown without infuscation (Figure 108); basal cell partly closed, with 2 long setae on disc; basal setal line with 2 long setae, costal setal line quite indistinct with 1 setae. Propodeum orange with a median black band; hairs on callus pale. Gaster colour mostly brown- yellow; T3 petiolate, black at insertion and then turning to brownish; T4 yellow; T5 with a transverse brown band on anterior suture; T6 with a small triangular brown spot on the middle; T7 with a larger triangular brown spot on the middle, and a small rounded brown spot on each side; T8 with a small rounded brown spot on each side. Long black hairs on tergite sutures. Genitalia with elongate aedeagus, its part above digitus about 1.8 × as long as digitus length; digitus with 3 teeth; phallobase elongate, about 2.8 × as long as wide (Figure 107).

Head about 1.1 × as wide as long in front view (Figure 105). POL: OOL: 1.2. Scape 1.3 × as long as combined length of pedicel, anellus, and F1 (Figure 106); scape 0.9 × as long as combined length of pedicel, anellus, F1 and F2; F1 1.4 × as long as pedicel, 2.1 × as long as wide; F1 1.2 × as long as F2; following funicular segments elongate, not tending to subquadrate; F7 2.0 × as long as wide. Pronotum with coarse transverse carinae, mid-lobe of mesoscutum and axilla with transverse striae finer than on pronotum (Figure 104). Mid-lobe of mesoscutum 1.2 × as long as scutellum length; Scutellum 1.3 × as long as wide, noticeably covered with irregular, arching, concentric wrinkles; frenum nearly indistinct from scutellum. Forewing stigma oblique, rounded, about 1.2 × as long as wide (Figure 108); upper part of stigmal vein 0.4 × as long as stigma length; uncus very short, 0.4 × as long as upper part of stigmal vein.

Dark form. Larger than pale form, with body length 5.7 to 6.4 mm. Body colour substantially black (Figures 109-112) with a conspicuous, large triangular infuscation around the forewing stigma (Figure 114). Head mostly black except a transverse dirty yellow band on the lower face (restricted to gena in some specimens) and a dirty yellow spot between eye and posterior ocellus (Figure 112). Thoracic dorsum dirty yellow with a large median black band extending from the anterior suture of pronotum to frenum (Figure 111). Sides of thorax entirely black (Figure 110). Legs mostly dark; coxae black; fore femora brownish in its basal part, mid- and hind femora quite entirely brownish; tibiae and tarsi yellow. Propodeum entirely black. Antenna (Figure 113), thoracic sculpture (Figure 111), pilosity and genitalia (Figure 115) similar to pale form.

Intermediates. Some specimens show a slightly infuscated stigma along with head and thorax mostly orange but with more blackish patterns than in the pale form: a black-brown band between eye margin and torulus, a brownish median band on thorax from anterior suture of pronotum to posterior suture of mid lobe of mesoscutum which prolongates in a fuzzy median band on scutellum, and a brown longitudinal band on upper and lower part of mesepimeron. Legs yellow with a large black spot on fore coxa, a smaller spot on mid-coxa, and a brownish infuscation on hind coxa. Propodeum with a large median black band, black spots around spiracles, and a brownish infuscation at suture with callus. Pilosity is similar to the one of pale from but some individuals have 3 pairs of hairs on scutellum.

Host plants.

Lannea rivae ( Anacardiaceae ). Probably a seed feeder. Although the presence of numts was noted in the COI sequences of the only specimen of Megastigmus lanneae which amplified for DNA analysis, this species clearly clustered within the " Anacardiaceae clade" (Figure 14) as already noticed for Megastigmus ozoroae .

Distribution.

Known only from farmland tree in Machakos area. Adults emerged from 3.3% of the collected fruits (Table 3).

Etymology.

Named after the genus of its host plant.

Diagnosis.

Females can be separated easily from those of other species associated with fruits of Anacardiaceae by the combination of an ovipositor at least 1.8 × as long as gaster length and a yellow and brownish body. In other species having dark and yellow patterns, the ovipositor length is either shorter than gaster length ( Megastigmus ozoroae - Figure 43, Megastigmus smithi - Figure 31) or at most 1.5 × longer ( Megastigmus hypogeus - Figure 117). Body colour is predominantly orange in Megastigmus laventhali , Megastigmus pistaciae , Megastigmus thomseni and Megastigmus transvaalensis . Genitalic characters allow separation of Megastigmus lanneae males from those of other species developing in seeds of Anacardiaceae . The aedeagus part above digitus is significantly longer (1.8 × as long as digitus length) than in Megastigmus hypogeus (1.2 –1.3×; Figures 127, 134), Megastigmus pistaciae (0.8 ×; Figure 148) and Megastigmus transvaalensis (0. 5 ×; Figure 162). The aedaegus dimension compared to digitus is similar in Megastigmus ozoroae but the phallobase of Megastigmus lanneae is more elongate (2.8 × vs. 2.6 × longer than wide; Figures 53, 60).