Baeus dux Girault

Stevens, N. B. & Austin, A. D., 2007, Systematics, distribution and biology of the Australian ' micro-flea' wasps, Baeus spp. (Hymenoptera: Scelionidae): parasitoids of spider eggs., Zootaxa 1499, pp. 1-45 : 17-18

2. Baeus dux Girault

(Figs 8A & B, 15A)

Baeus dux Girault , 1933: 2: in Gordth et al. 1979: 300; Austin, 1981: 89; Johnson, 2004.

Holotype, [[female]], ' Brisbane , garden on grass, Sep. 8, 1932, A. R. Brimblecomb' ( QM).

Other material examined: Queensland: 2 [[females]], Gatton , Qld, 27.iv-5.v.1981, yellow pan trap in potato crop, no collector ( ANIC) ; 2 [[females]], same data, 5-11.v.1981 ( ANIC) ; 1 [[female]], same data, 25.v-3.vi.1981 ( ANIC) ; Norfolk Island: 1 [[female]], 29.07S 167.57E, Phillip Island, Lower Long Valley , 20-24.ii.1984, T. A. Weir, pitfall trap ( ANIC) .

Description. Female. Mean length0.64 mm (0.63-0.65; n = 3); body and head dark brown, nearly black, leg and antennae segments yellow with light brown markings on dorsal surfaces.

Head. 1.71 (1.65-1.82) x as wide as inter-ocular distance and 1.89 (1.75-2.07) x as wide as long; medial ocellus 10 µm in diameter, 80 µm from posterior head margin; lateral ocelli 5 µm from eye margin, 20 µm from posterior head margin; posterior ocellar line = inter-ocular distance; vertex imbricate, pilosity density gradates, anterior to posterior, from moderate to dense, and is medium length; eyes sub-triangular, eye height 0.44 (0.43-0.46) x head height, eye width 0.55 (0.5-0.64) x eye length, pilosity short; frontal carina prominent, reaching 0.55 (0.53-0.59) distance to medial ocellus; cristulations of malar region reaching to within 10 µm of eye margin; in postero-lateral view, anterior and posterior genal margins parallel medially; anterior genal margin in contact with 0.43 (0.4-0.5) of ventral eye margin length; posterior eye margin 20 µm from posterior head margin, not contacting hyperoccipital carina.

Mesosoma. Length 0.72 (0.71-0.73) x width; both mesoscutum and mesoscutellum imbricate, pilosity mostly dense, patches of moderate density can be present, and of medium length; propodeum glabrous mediodorsally; mesoscutum length 0.60 (0.57-0.63) x width, 0.73 (0.71-0.75) x mesosoma length and 3.71 (3.43- 4.00) x mesoscutellum length; mesoscutellum length 2.56 (2.33-3.0) x propodeum length; dorso-lateral region of mesopleuron scrobiculate, sculpturing ending dorsally to dorsal metapleuron margin; dorso-lateral propodeum bearing a semi-circular ridge beginning near posterior margin of the propodeum and extending through ventral region of propodeal spiracle cone, before curving back to end near posterior margin of lateral propodeum (Figs 8A&B); propodeal spiracle small and ovoid; posterior suture of metapleuron straight and short, dorsal extent of suture ending below the level of antero-lateral margin of T2; hind femoral spine absent.

Metasoma. T2 length 0.9 x width, anterior region imbricate to finely coriarious, to smooth posteriorly, pilosity dense anteriorly to moderately dense posteriorly, of medium length overall; T3 smooth, bearing one row of setae of medium length; T4 glabrous.

Comments. The distinguishing feature for B. dux is its distinct semi-circular ridge on the dorso-lateral propodeum. Baeus leai is the only other species to possess a similar structure. However, the two species are very different in many other characters, namely, the shape of the gena, sculpturing of the dorsal mesosomal, and smaller body and eye size.

Baeus dux has been collected from south-eastern Queensland (Fig. 15A) and Philip Island near Norfolk Island.

The habitats from which some specimens were collected include a suburban garden and a potato crop, indicating that the host(s) are tolerant of, or may prefer, heavily disturbed sites.