Baeus matthewi, Stevens, 2007

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 : 27-29

9. Baeus matthewi, Stevens , sp. nov.

(Figs 11A & B, 16A)

Holotype, ♀, Queensland, ' 12.41S 142.41E, QLD, 5 km S Batavia Downs . 23 Aug-16 Sep 1992. Flight Intercept trap P. Zborowski & L. Miller ' ( ANIC).

Paratypes: Queensland: 2 ♀♀, Eungella N.P. , 29.xi.1976, Boucek, 8-9.v. 1980, I.D. Naumann & J.C. Cardale ( ANIC) ; 1 ♀, Tinaroo Creek Rd, 26 km up via Mareeba , 12-28.i.1983, Storey & Brown ( ANIC) ; 2 ♀♀, same data as holotype ( ANIC) ; 1 ♀, Heathlands , 11.45S 142.35E, 25.vii-18.viii.1992, P. Zborowski & J. Cardale ( ANIC) ; 1 ♀, Mt Haig , 17.06S 145.36E, 4.ii-17.iii.1995, P. Zborowski ( ANIC) ; 1 ♀, Mt Edith , 17.06S 145.37E, 30.vi-31.vii.1995, P. Zborowski ( ANIC) ; Australian Capital Territory: 1 ♀, Canberra, Black Mountain , 36.16S 149.06E, 22-28.ii.1998, yellow pan trap, G. Gibson ; South Australia: 3 ♀♀, Brachina Gorge , 31.30S 138.34E, 4-10.xi.1987, I. Naumann & J. Cardale ( ANIC) .

Description. Female. Mean length 0.82 mm (0.74-0.86; n = 5); body and head range from black to dark brown, legs and antennae yellow with darker markings on dorsal surfaces.

Head. 2.25 (2.17-2.38) x as wide as inter-ocular distance, and 1.86 (1.59-2.00) x as wide as long; medial ocellus 15 µm in diameter, 82 (80-90) µm from posterior head margin; lateral ocelli touching eye margin, 20 µm from posterior head margin; lateral ocelli very close to (<5 µm) or touching eye margin; posterior ocellar line 1.24 (1.20-1.31) x inter-ocular distance; vertex coriarious, pilosity generally sparse but may be moderately dense posteriorly, generally of medium length but bordering on short which it can be in areas; eyes large and ovoid, eye height 0.53 (0.48-0.55) head height, eye width 0.59 (0.56-0.61) x length, pilosity short; frontal carina prominent, reaching 0.57 (0.54-0.68) distance to medial ocellus; lateral cristulations of malar region extending to within 10 µm of eye margin; in postero-lateral view, anterior and posterior genal margins convergent medially; anterior genal margin in contact with 0.5 of ventral eye margin length; posterior eye margin touching hyperoccipital carina.

Mesosoma. Length 0.55 (0.47-0.60) x width; mesoscutum and mesoscutellum coriarious, pilosity mostly of moderate density, though can be dense in the anterior row of mesoscutellum, and sparse in posterior parts of both sclerites, is of medium length overall though often bordering on being short; propodeum glabrous medio-dorsally; mesoscutum length 0.42 (0.36-0.47) x width, 0.66 (0.63-0.67) x mesosoma length, and 2.86 (2.50-3.00) x mesoscutellum length; length mesoscutellum 2.1 (2.0-2.5) x propodeum length; sculpturing dorsal mesopleuron scrobiculate, may end adjacent to or ventral to dorsal margin of metapleuron; sculpturing of propodeum anterior to spiracle confused, region posterior to spiracle carinulate; propodeal spiracle opening round and distinct, with margins prominently raised; dorsal and lateral propodeum delineated by a broad laterally projecting carina (e.g. Fig. 10C); posterior margin of metapleuron relatively parallel to anterior margin medially, but dorsally curving sharply, nearly at right angles, towards mesopleuron, ending adjacent to level of antero-lateral margin of T2; ventro-posterior metapleuron elevated from anterior margin of lateral propodeum; hind femoral spine> 15 µm in length.

Metasoma. T2 length 0.90 (0.89-0.91) x width, sculpturing coriarious, pilosity mostly sparse, but can be of moderate density in medial anterior areas, is mostly of medium length, often bordering on short, which it can be in areas; T3 coriarious anteriorly with wide smooth, nitid band along posterior margin, one row of setae present along posterior extremity of sculpturing; T4 glabrous.

Comments. Baeus matthewi is clearly recognisable from other species because of its large hind femoral spine that is very distinct under stereo-light microscopey. The only other species to possess such large spines is B. vulcanus , which also has large propodeal spiracles (opening? 20 µm in diameter) that are clearly distinguishable from the smaller spiracles of B. matthewi .

This species has mainly been collected along Cape York Peninsula as far south as Mareeba, except for several specimens collected from the Flinders Ranges in South Australia, and from Canberra (Fig. 16A). The contrasting climatic conditions among the regions possibly indicates that the distribution of Baeus spp. is largely determined by host distribution rather than environmental conditions.

This species is named after the brother of the senior author, Mr Matthew Stevens.