Leptoomus janzeni Gibson , 2008

Simutnik, Serguei A., Perkovsky, Evgeny E. & Vasilenko, Dmitry V., 2020, First record of Leptoomus janzeni Gibson (Hymenoptera, Chalcidoidea) from Rovno amber, Journal of Hymenoptera Research 80, pp. 137-145 : 137

Leptoomus janzeni Gibson, 2008

Figs 1 , 2A-E

Material examined.

SIZK VT-95, 1 ♀, Velyki Telkovichi, Rovno amber; late Eocene. The inclusion is in a clear amber piece (about of 30 × 14 × 8 mm) of irregular shape (Fig. 1A ). A syninclusion consists of a precariously preserved small insect with only the legs visible.

Measurements.

Body length 2.45 mm; other reported measurements are relative (one micrometer division = 0.014 mm) and are approximate because of optical effects in the amber.

Head. Head length 26, width 46, height 38; eye height 15; malar space 15; posterior ocellus diameter 3; OOL 1.5; POL 7; OCL 6; LOL 5; distance between toruli 7, between torulus and eye 9, from torulus to mouth margin 6; length to width ratio of scape 25:7, pedicel 8:4, F1 2:4, F2 3:4.5, F3 4:5, F4 3:5, F5 3:5.5, F6 3:6, F7 3:7 (very approximately), clava 7.5:10, micropilose sensory region 5:7.5.

Mesosoma. Mesosoma length 68; length to width ratio of mesoscutum 30:30, scutellum 26:21; prepectus maximal length 16, height 15.

Appendages. Length to width ratio of fore wing 120:55; mv:pmv:stv about 22:18:15; length to width ratio of hind wing 77:25; protibia 30, protibial spur (calcar) 8; mesotibia 48, mesobasitarsus 12, mesotibial spur 11.

Metasoma. Length 77, height 45 (lateral view), width 45; ovipositor stylet from hypopygium margin 41.

Comparison with L. janzeni type material.

The Rovno amber specimen differs from the Baltic amber material by having slightly infuscate, brownish, rather than hyaline forewings. The head and thorax have a distinct green metallic sheen not seen in the Baltic specimen (Figs 1C, D ). Multiporous plate sensilla on the flagellum were not described by Gibson (2008), but are visible in the Rovno specimen on F3-F7, and on the apical two segments of the 3-segmented clava (Figs 1E, F, G ); F4 appear to have only a single mps but the others have multiple mps in a single row per segment that does not fully encircle the segment.

Also, in the Rovno specimen the spur vein originating from the marginal venation of the hind wing is visible (Fig. 2E : spv). In addition to Tanaostigmatidae , some Pteromalidae (for example, Nasonia ), and some Eupelmidae (e.g. Pentacladia , Fig. 2F : spv) also have a similar sclerotized spur vein.

The only uniquely shared feature of L. janzeni and Tanaostigmatidae is that in both the prepectus extends anteriorly, exterior to pronotum, though in L. janzeni it is flatter and its lateral panel is bare (Figs 1B , 2A : pre).

The metatibia of the new specimen has two spurs (Fig. 2C ). This character L. janzeni shares the with many other chalcidoid taxa.

The metanotum is not clearly visible because the wings are positioned over the gaster. The dorsellum (Fig. 1D : dor) appears to taper posteriorly to fit into a broadly incised anterior margin of the propodeum such that the medial length of the dorsellum is greater than the medial length of the propodeum.

Figures

Figure 1. Leptoomus janzeni, female VT- 95 from Rovno amber (deposed in SIZK) A piece of amber containing the specimen B habitus ventrolateral (left side) C habitus dorsolateral (right side) D head and mesosoma dorsolateral, dorsellum E antenna ventral F antenna dorsal G head frontolateroventral, part of antenna with mps arrowed H forewing I protibial spur, protarsus J mesotibial spur, mesotarsus.

Figure 2. A-E L. janzeni, female A mesosoma ventrolateral B apex of metasoma lateroventral C metatibial apex with two spurs D metasoma lateral E venation of hind wing with spur vein F Pentacladia sp., female, venation of hind wing.