Baeus arthuri, 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 : 15-17

1. Baeus arthuri, Stevens , sp. nov.

(Figs 4A, 5A, 6A & B, 7A, 15A)

Holotype, [[female]], Queensland, ' N. Qld: East Palmerston , 15.v.1991, R. Piper' ( ANIC).

Paratypes: Queensland: 28 [[females]], 4 [[males]], same data as holotype ( ANIC, WINC) ; 6 [[females]], 11.45S 142.35E, Heathlands , 23.v-18.vi.1993, P. Zborowski & I.D. Naumann, F.I.T. ( ANIC) ; 15 [[females]], 11.45S 142.35E, Heathlands , 25.vii-18.viii.1992, P. Zborowski & J. Cardale, M.T. ( ANIC, WINC) ; 1 [[female]], 11.45S 142.35E, Heathlands , 21.x-22.xi.1992, P. Zborowski & A. Calder, F.I.T. ( ANIC) ; 2 [[females]], 11.45S 142.35E, Heathlands , 5.iv-23.v.1993, P. Zborowski & A. Roach, F.I.T. ( ANIC) ; 2 [[females]], 11.45S 142.35E, Heathlands , 18.ix-21.x.1992, P. Zborowski & T. Weir, F.I.T. ( ANIC) ; 1 [[female]], 11.45S 142.35E, Heathlands , 25.iv-7.vii.1992, T. McLeod, M.T. ( ANIC) ; 7 [[females]], 12.41S 142.41E, 5km S Batavia Downs , 23.viii-16.ix.1992, P. Zborowski & L. Miller, F.I.T. ( ANIC) ; 6 [[females]], 13.43S 143.19E, 15km WNW Bald Hill, McIlwraith Range , 420m, 27.vi-12.vii.1989, I. D. Naumann, pan trap ( ANIC) ; 1 [[female]], 16.52S 145.40E, Lake Placid, Barron River , 7.vi.1996, C.J. Burwell ( ANIC) ; 1 [[female]], Conway Range , 2.xii.76, Boucek ( ANIC) ; 1 [[female]], 15.16S 144.59E, 14km WbyN of Hope Vale Mission , 7-10.v.1981, I.D. Naumann ( ANIC) ; Northern Territory: 1 [[female]], Wangi Falls, Litchfield National Park , xi.1992, A.D. Austin & P.C. Dangerfield ( WINC) ; Papua New Guinea: 1 [[female]], Awar Bush Street , 21.vi.1982, 24.vii.1982, 31.vii.1982, 12.x.1982, P. Grootaert ( CNC) ; 1 [[female]], Morobe Pr. Wau Ecology Institute , viii.1983, S. & P. Miller ( CNC) ; Fiji: 1 [[female]], Vanua Leevu, Mt Delaikara , 700m, 21.vii.1987, Monteith and Cook, pyrethrum /logs and trees ( QM) .

Description. Female. Mean length 1.04 mm (0.93-1.12 mm; n = 10); body dark brown, almost black, head dark brown, legs and antennae yellow with darker colouration dorsally.

Head. 2.2 (2.08-2.33) x as wide as inter-ocular distance, and 2.19 (1.73-2.58) x as wide as length; medial ocellus level with surface of vertex; medial ocellus 10 µm in diameter, 120 (110-130) µm from posterior head margin; lateral ocelli 10 µm from eye margin, and 24 (2.0-3.0) µm from posterior head margin; posterior ocellar line 1.3 (1.24-1.3) x inter-ocular distance; vertex coriarious, pilosity sparse with mixture of short and medium length setae (medium length mostly within 10-15 µm range, not exceeding 20 µm); eyes circular, eye height 0.5 (0.45-0.49) x head height, eye width 0.7 (0.61-0.74) x eye length, pilosity minute, appearing absent under stereo-light microscope; frontal carina not prominent, fine and short, reaching 0.45 (0.42-0.48) distance to medial ocellus; cristulations of malar region not reaching to within 10 µm of eye margin; gena sinuate with anterior and posterior genal margins strongly convergent medially in postero-lateral view; anterior genal margin in contact with 0.3 (0.2-0.3) of ventral eye margin length; posterior eye margin contacting hyperoccipital carina.

Mesosoma. Length 0.43 (0.41-0.46) x width; mesoscutum finely coriarious, pilosity sparse and mostly of medium length, but can be short in patches; mesoscutellum smooth, with one row of setae present medio-dorsally, sparsely spaced and of medium length; propodeum glabrous medio-dorsally; mesoscutum length 0.32 (0.29-0.36) x width, 0.56 (0.53-0.58) x mesosoma length and 2.28 (2.20-2.50) x mesoscutellum length; mesoscutellum length 1.32 (1.0-1.67) x propodeum length; dorso-lateral mesopleuron and propodeum anterior to propodeal spiracle scrobiculate; dorso-lateral propodeum posterior of spiracle smooth and bearing fine short setae; dorsal and lateral propodeum clearly delineated by broad laterally projecting carina (e.g. Fig. 10C); posterior margin of metapleuron mostly straight, except curving sharply towards mesopleuron dorsally, dorsal extent of suture is above level of antero-lateral margin of T2, posterior margin elevated above anterior margin of lateral propodeum; hind femoral spine absent.

Metasoma. T2 length 0.93 (0.9-0.96) x width, faintly coriarious to smooth, pilosity sparsely scattered and mostly short, but can be of medium length in patches, posterior margin extending ventrally past ventral margin of pronotum; T3 smooth with one row of setae, sparsely spaced and short, may appear devoid of setae; T4 glabrous.

Description. Male. Mean length 1.11 mm (1.06-1.16; n = 2);

Head. 1.5 (1.3-1.6) x as wide as inter-ocular distance and 2.5 (2.3-2.8) x as wide as long; medial ocellus 22 µm in diameter, 110 (99-121) µm from posterior head margin; lateral ocelli 22 µm from eye margin, 35.8 (33-38.5) µm from posterior head margin; posterior ocellar line equal to inter-ocular distance; eyes ovoid, eye height 0.51 x head height; frontal carina reaching> 0.5 distance to medial ocellus; in postero-lateral view, anterior and posterior genal margins slightly convergent medially; anterior genal margin contacting the entire length of ventral eye margin; posterior eye margin> 45 µm from hyperoccipital carina.

Mesosoma. Length 1.13 x width; mesoscutum length 0.9 x width, 0.68 x mesosoma length; propodeal spiracle small and round; hind femoral spine absent.

Metasoma. T1 transverse, length 0.18 (0.17-0.19) x width; T2 length 0.5 (0.4-0.6) x width.

Comments. This is a large species, characterised by sparse and short pilosity, with mostly smooth, shiny dorsal surfaces, and gena being sinuate with strongly convergent margins medially. Baeus arthuri is most similar to B. scrobiculus except the dorsal surfaces are smoother, and the scrobiculate sculpturing of the dorso-lateral propodeum is not as extensive. The holotype, along with 28 female and four male paratypes, were all reared from a single, unidentified host egg-sac. Therefore, B. arthuri is one of only a few Australian Baeus species that has reliably associated males.

Baeus arthuri is confined to the more tropical areas of northern Australia (Fig 15A) and extends to Papua New Guinea and Fiji.

This species is named after the father of the senior author, Mr Arthur Stevens.