Antennal scape distinctly longer than head; vertex sharply declivous behind ocelli; cervical expansion of head with posterior shield-like expansion clearly separate from rest of head; forewing venation highly reduced, restricted to basal sixth or less; all tibiae without flanges.

China (Hainan Island), Thailand, Malaysia, and Indonesia.

Unknown.

Holotype, ♀, Thailand, Phrae Prov. 153 m, Mang Chin Dist., nr. Wiang Kosai NP, 3. V. 2019, R. Ishikawa leg. (Entomological Laboratory, Faculty of Agriculture, Kyushu University).

Female (Fig. 1). Body 3.0 mm long.

Figure 1. 

Lateral habitus of Radinoscelidia lixa sp. nov. (holotype). Scale bar: 1 mm.

Head. Head (Figs 2–4) 1.9 times as long as height in lateral view, 1.3 times as long as maximum width; minimum length between compound eyes 0.7 times as long as head width; frontal projection rectangular in frontal view (Fig. 3); apical margin of frontal projection depressed (Fig. 2); malar space striate; frons striate radially except smooth appressed area in front of midocellus (Fig. 2); low ridge present from around posterior part of inner orbit of eye to posterior depression of vertex; vertex without transverse ridge, deeply depressed posteriorly; cervical expansion curved in lateral view (Fig. 4); temple 3.3 times as long as MOD; POL 2.5 times as LOD; OOL 3.0 times as long as LOD; LOL as long as LOD; scape 4.3 times as long as wide, sparsely punctate, slightly curved, 0.8 times as long as head width (Fig. 5); flange of scape 0.3 times as long as scape length; maximum width of flange 0.6 times as wide as tubular part of scape (Fig. 5); pedicel 1.3 times as long as wide, 0.5 times less than F1; F1–F7 tubular; relative length (width) of F1–F11: 2.4 (1.1): 2.0 (1.2): 1.8 (1.2): 1.6 (1.0): 1.4 (1.0): 1.4 (1.0): 1.4 (1.0): 1.4 (1.1): 1.4 (1.1): 1.4 (1.1): 3.2 (1.2).

Figures 2–5. 

Head of Radinoscelidia lixa sp. nov. (holotype) 2 dorsal 3 frontal 4 lateral 5 antenna. Scale bars: 0.5 mm.

Mesosoma. Mesosoma polished (Figs 1, 6); pronotum 0.9 times as long as maximum width; maximum width of pronotum 1.5 times as wide as posterior width; lateral margin of pronotum without distinct ridge (Fig. 6); mesoscutum 1.1 times as long as wide; tegula polished, 1.5 times as long as wide (Fig. 6); mesoscutum with notauli reaching posterior margin; mesoscutellum polished, 1.6 times as long as maximum width, 4.4 times as long as metanotum length (Fig. 7); length between metanotal depressions 1.5 times as long as length of metanotum (Fig. 7); propodeum smooth; projection weakly developed; dorsal margin of propodeum concave above foramen (Figs 1, 7).

Figures 6, 7. 

Mesosoma of Radinoscelidia lixa sp. nov. (holotype) 6 dorsal 7 lateral. Scale bars: 0.5 mm.

Legs. Legs polished (Fig. 1); femora cylindrical; tibiae slightly flattened, with longitudinal ridge on lower side; forefemur 4.1 times width; foretibia 5.9 times as long as width; midfemur 4.8 times as long as width; midtibia 6.6 times as long as width; hindcoxa 2.4 times as long as hindtrochanter; hindfemur 5.1 times as long as maximum width, 1.5 times as long as head width; hindtibia nearly straight, 8.1 times as long as maximum width (Fig. 1); hindbasitarsus 0.55 times as long as head width; relative length of hindtarsomeres = 3.5: 1.8: 1.7: 1: 2.3; tarsal claws with median tooth.

Wings. Fore and hindwings broken, missing from basal portion (Figs 6, 7).

Metasoma. Metasoma polished and smooth.

Pilosity. Frons with sparse decumbent needle-like setae; eye without setae; frontal projection with dense erect needle-like or cuneate setae (Fig. 2); clypeus with sparse erect needle-like setae (Fig. 3); maxilla with dense decumbent needle-like setae; labrum with dense decumbent needle-like setae; malar space with sparse suberect cuneate or forked setae (Fig. 4); temple with sparse decumbent needle-like setae; vertex behind ocelli with sparse suberect needle-like setae; vertex with ribbon-like setae, shorter than ribbon-like setae on cervical expansion (Figs 2, 4); cervical expansion with sparse decumbent needle-like setae and ribbon-like setae, longer than ribbon-like setae on vertex; upper gena with ribbon-like setae, as long as ribbon-like setae on pronotum (Fig. 4); lower gena with sparse suberect needle-like setae along occipital carina; scape with sparse decumbent needle-like setae and sparse suberect forked setae (Fig. 5); pedicel with dense decumbent needle-like setae; F with dense decumbent needle-like setae, shorter than each F length (Fig. 5).

Anterior margin of pronotum with ribbon-like setae (Fig. 6), as long as those on lower gena; pronotum with sparse suberect cuneate or forked setae in dorsal view (Fig. 6); pronotum with sparse decumbent cuneate or forked setae in lateral view; propleuron with sparse decumbent cuneate or forked setae (Fig. 1); mesoscutum with sparse suberect forked setae (Fig. 6); tegula with sparse suberect forked setae (Fig. 6); mesopleuron with sparse decumbent cuneate or forked setae; metanotum with sparse suberect forked setae (Fig. 7); propodeum with sparse suberect cuneate setae in lateral view (Fig. 7).

Apical half of fore and midcoxae with dense suberect needle-like setae (Fig. 1); femora with sparse erect or suberect cuneate setae (Fig. 1); apical part of coxae with dense decumbent cuneate setae; tibiae with dense decumbent needle-like setae; tarsomeres with dense decumbent needle-like setae.

T2–T3 with sparse decumbent setae (Fig. 1), shorter than setae on S3–S4; S3–S4 with sparse suberect needle-like setae (Fig. 1); T5 with sparse suberect needle-like setae; S5 with dense suberect needle-like setae.

Coloration. Body reddish-brown (Fig. 1); labial palpi, maxillary palpi, and ribbon-like setae brownish yellow; other setae white; flange yellowish brown.

Male. Unknown.

Named after the Latin ‘lixa’, meaning camp-follower, referring to the wasp walking near the ant’s trail.

Thailand (Phrae).

Carebara diversa (Hymenoptera, Formicidae) (Fig. 8).

Figure 8. 

Lateral habitus of Carebara diversa. Scale bar: 1 mm.

Rhadinoscelidia lixa sp. nov. is easily distinguished from other species by the following characters: scape 4.3 times as long as width (over 5 times as long as width in other species); short erect setae of antenna; wide ribbon-like setae on temple wider than those on pronotum (shorter than those on pronotum in other species); shorter ribbon-like setae on cervical expansion (relatively longer in other species); straight hindtibia (slightly or moderately curved hindtibia in other species).