Rhysacephala novacaledonica Jennings & Austin

Jennings, John T., Austin, Andrew D. & Schiff, And Nathan M., 2007, Rhysacephala novacaledonica sp. nov. (Hymenoptera: Xiphydriidae), the first xiphydriid woodwasp from New Caledonia, Zootaxa 1516, pp. 23-30 : 25-29

Rhysacephala novacaledonica Jennings & Austin , sp.nov.

( Figs 1–7 )

Material Examined

Holotype: ɗ " New Caledonia 22º14'Sx 166º50'E Pic du Pin, site 2, 280m 26Nov2004 hand netting Burwell, Wright, rainforest". Deposited in the Muséum National d'Histoire Naturelle, Paris. Last 5 flagellomeres of left antenna and right hind tarsal segments 2–5 and claw missing.

Description

Male: Length 7.0 mm ( Fig 2). Head dark brown, thorax and abdomen black except for a broad yellow stripe on face along lower inner orbits of eyes, gena, malar space and lower hind orbits. Irregular yellow patch medially on lower frons and interantennal area, mandible yellow with brown margins, ventral surface of propleuron and thoracic sternites largely yellow, cenchri white, yellow dot medially on mesepisternum, antennae and legs light brown except variable amounts of yellow ventrally on coxae. Fore wing with a dark brown tint, hind wing lighter brown tint ( Fig. 3 ).

Head 1.24 x wider than long when viewed dorsally ( Fig. 4 ). Face rugose ( Fig. 5 ). Inner orbits of eyes more or less parallel ( Fig. 5 ). Distance between antennal sockets 3 x distance between an antennal socket and front of clypeus ( Fig. 5 ). Vertex smooth except for a few scattered shallow punctures posteromedially, rugose near ocelli ( Fig. 4 ). Gena smooth, carina present. Malar space 0.32 x height of eye, distinct antennal groove. Occipital carina broad ( Fig. 4 ). Clypeus strigate. Mandible 4-dentate. Maxillary palp 7-segmented, labial palp 4-segmented. Antenna 19-segmented, scape 2.2 x length pedicel, first flagellomere equal to length of scape, 1.7 x as long as second flagellomere. Pedicel 2.3 x longer than wide.

Pronotal collar hidden on specimen, lateral corner carinate ( Fig. 7 ). Mesoscutum strigate, with reticulate microsculpturing, medial patch on lateral mesoscutum reticulate (Figs 6,7). Mesoscutellum without dorsal area defined by a carina, without prominent tubercle near apex ( Fig. 6 ). Axillae strigate. Metascutellum strigate with reticulate microsculpturing. Metapostnotum and mesepisternum rugose. Mesopleuron rugose anteriorly, imbricate posteriorly. Metapleuron rugose dorsally, rugulose ventrally. Mesepimeron broad, carinate. Hind femur 0.9 x length hind tibia. Tibiae with two apical spurs, although inner one very short on fore tibia. Hind basitarsus slightly longer than remaining segments combined, bilobed tarsal plantulae present distally on segments 1-4. Tarsal claws with small erect inner tooth. Fore wing vein 2A+3A complete, more or less even in colouration although apical part slightly paler, almost reaching wing margin ( Fig. 3 ). Hind wing veins 3r-m and 2m-cu present ( Fig. 3 ). Hind wing with 5 hamuli basally and 6 hamuli medially. Abdomen 2.4 x length thorax ( Fig. 2), reticulate microsculpturing.

Female: Unknown.

Remarks

This species lacks a prominent tubercle near the apex of the mesoscutellum ( Fig. 6 ) placing it in the Xiphydriinae rather than the Derecyrtinae. It also has bilobed tarsal plantulae which are absent in most Derecyrtinae ( Benson 1954; Smith 1978; Schulmeister 2003), although present in A. australiensis Riek (Jennings unpublished). It exhibits the main characteristics for Rhysacephala as defined by Maa (1949), and modified by Benson (1954), including the inner orbits of the eyes being more or less parallel and having 7-segmented maxillary palps. The fore wing vein 2A+3A is more or less even in colour although apically a little paler, and almost reaches the wing margin ( Fig. 3 ); in this respect it is not too dissimilar to the original diagnosis for the genus ( Maa 1949; Benson 1954). Any differences are relatively minor and do not require the generic limits of Rhysacephala to be modified to accommodate this new species.

Although this species is similar in colour to the females of both R. obtusiventris and R. rufipes in which both the thorax and abdomen are black, it differs from the female of R. wilsoni which has a black thorax and a reddish brown abdomen, Rhysacephala novacaledonica can be distinguished from the male of R. leai in which both the thorax and abdomen are pale reddish brown. It can be distinguished from the male of R. testacea which also has the abdomen “infuscatus” (darkened), by R. novacaledonica having 19-segmented antennae compared with 13-segmented in R. testacea ( Mocsáry 1900) . It should be noted that a degree of caution must be exercised when comparing the colouration of different sexes as there is often a difference between the sexes.

The head of R. novacaledonica is similar to that of R. leai . Both have a broad yellow stripe on the face along the lower inner orbits of the eyes, gena, malar space and lower hind orbits, although the remainder of the head of R. leai is black whereas it is brown in R. novacaledonica ( Fig. 5 ). It differs from R. obtusiventris , R. rufipes , R. testacea , and R. wilsoni which lack a stripe on the face and gena. It is interesting to note that Cingalixiphia laeviceps, which is distinguished from Rhysacephala by having a simple hind claw, also has a similar yellowish-white stripe ( Smith 1861).

Rhysacephala novacaledonica is known only from the type locality, Pic du Pin, New Caledonia ( Fig. 1 ), and is named after this island. The name is to be treated as an adjective. Its biology is unknown. In Brazil, the xiphydriid woodwasp Derecyrta araucariae Mecke is associated with Araucaria angustifolia (Bertol.) Kuntze ( Mecke et al. 2000) . Some 13 species of Araucaria and five species of Agathis (Araucariaceae) are endemic to New Caledonia ( Lowry 1998), and it seems reasonable to hypothesise that xiphydriid woodwasps may be associated with Araucariaceae in New Caledonia. Similarly, D. beechei Smith (Cupressaceae) has been collected in Chile from Fitzroya cupressoides (Molina) Johnston forest ( Smith 1995), so other potential hosts in New Caledonia might also include Cupressaceae . Both Callitris spp. and Neocallitropsis spp. occur in New Caledonia ( Pye et al. 2003). Finally, Basset (1991) noted that Rhysacephala were found in the canopy of an Argyrodendron actinophyllum forest near Brisbane, Australia, although it is not clear whether it is its host.

Whilst Argyrodendron is an Australian genus, the genus Acropogon , with more than 20 species endemic to New Caledonia ( Morat & Chalopin 2005), might be worth exploring as potential hosts.

Figures

FIGURE 1. Distribution of Xiphydriidae in Australasia. A = Austrocyrta australiensis Riek; C = Cingalixiphia laeviceps; M = Moaxiphia spp.; L = Rhysacephala leai; N = R. novacaledonica sp. nov.; O = R. obtusiventris R = R. rufipes; T = R. testacea; and W = R. wilsoni.

FIGURE 3. Wings of R. novacaledonica sp. nov. showing venation. Scale bar = 0.5 mm.

FIGURES 4 – 9. 4. Dorsal head of R. novacaledonica sp. nov.; 5. Frontal head of R. novacaledonica sp. nov.; 6. Dorsal thorax of R. novacaledonica sp. nov.; 7. Dorsal view of mesoscutum (M) and lateral corner of pronotum (P) of R. novacaledonica sp. nov.; 8. Dorsal scutellum, axillae and mesoscutellum of male of an undescribed Austrocyrta sp. from Mt Moffatt, Queensland, showing tubercule (arrowed) on scutellum; 9. Dorsal view of pronotal collar (P) and mesoscutum (M) of A. australiensis, female. Scale bars 4 - 6, 8 - 9 = 0.2 mm; 7 = 0.15 mm.