Arthula plebeja Ubaidillah and Kojima

Ubaidillah, Rosichon, Yamaguchi, Goshi & Kojima, Jun-Ichi, 2009, A new Arthula Cameron (Ichneumonidae, Cryptinae) parasitoid of Ropalidia plebeiana Richards (Vespidae) and host of Amoturoides breviscapus Girault (Torymidae) (Hymenoptera), Zootaxa 2274, pp. 45-50 : 46-47

Arthula plebeja Ubaidillah and Kojima , sp. nov.

( Figs 1–10 )

Diagnosis. Body mostly brown. Antenna with 23–24 flagellomeres in female, 27–28 flagellomeres in male; propleuron densely punctured; first metasomal tergum not strongly widened posteriorly, its apical width about 1.5x basal width, not very long, about 2.7x as long as its apical width; second tergum slightly shorter than or about as long as its apical width.

Female. Body length about 7.5–10 mm (n = 5) (holotype about 10 mm), forewing length about 6–7.5 mm (n = 5) (holotype about 7.5 mm).

Body mostly brown; stained with black along anterior margin of pronotum and anterior margin of mesoscutum, on prepectus, median part of mesopleoron, sub-lateral and sub-ventral parts of propodeum, and all coxae ( Fig. 1 ). Head and mesosoma with following yellow marks: stripe encircling eye and connected to transverse wide band below toruli, ill-defined band along apical margin of clypeus, narrow band along posterior margin of pronotum, paired oval anterolateral spots on mesoscutum, oval anterior spot on axilla, paired semi-rounded spots on dorsellum, posterior half of propodeum medially, and transverse stripe along posterior margin of each of second to fifth metasomal terga.

Head in frontal view ( Fig. 2 ) suboval, nearly 1.4x as wide as high, in dorsal view ( Fig. 3 ) about 2x as wide as long; occipital carina complete. Area among ocelli weakly raised, unmargined by either carina or suture; anterior and posterior ocelli nearly the same size; distance between inner margins of posterior ocelli about 1.5x their diameter, and about 0.8 of distance between outer margin of posterior ocellus and inner eye margin. Eye oval, bare, in frontal view inner margins nearly parallel; in profile maximum width of eye about 2x that of gena. Malar space about 0.4 of eye height. Face slightly raised medially, with paired broad and shallow oblique grooves diverging dorsally from bases of toruli. Clypeus oval, slightly convex, depressed ventromedially, separated from supraclypeal area by shallow arched groove, which is deeper in the ventrolateral corners. Maxillary palpus with five palpomeres; labial palpus with four palpomeres. Mandible tapering apically, with two teeth; dorsal tooth slightly larger and longer than ventral one ( Fig. 4 ). Antenna filiform, narrowing apically, with 23 (holotype) or 24 flagellomeres (3 paratypes), or number asymmetric (1 paratype); first flagellomere about 2.7x as long as its apical width, about 1.6x as long as second flagellomere; second to seventh flagellomeres nearly equal in length; subsequent flagellomeres becoming narrower and shorter towards apical part of flagellum; terminal flagellomere bullet-shaped, nearly 2x as long as its basal width (but 1.4–1.6x as long as wide when the flagellum has 24 flagellomeres).

Mesonotum closely punctured, densely covered with short setae; notaulus narrow, impressed, traceable in anterior half of mesoscutum; disk of mesoscutum moderately punctured, strongly wrinkled along notauli and over broad area behind their terminus, and alongside margins of lateral disk. Scutellum slightly convex dorsally, finely, closely punctured. Propodeum densely covered with short setae, coarsely reticulated to densely punctured medially and laterally, with short longitudinal rugae on anterior margin; median longitudinal carina absent. Mesopleuron densely covered with short setae, closely punctured, most coarsely on median disk; propodeal spiracle elliptical.

Forewing ( Fig. 5 ) radial cell 3.0–3.5x as long as wide; costal notch distinct; 2m-cu with two bullae. Hind wing with distal abscissa of 1A complete.

Metasoma finely and closely punctured, densely covered with short setae. First tergum ( Figs 6, 7 ) weakly widening posteriorly, in dorsal view apical width about 1.5x basal width, length (measured in lateral view as the distance from the apical margin of basal slit to posterodorsal corner of the tergum) about 2.7x its apical width, without glymma, basal half with two weak, sub-median carinae; spiracle strongly produced as tubercle at mid-length of the tergum; second tergum 0.9–1.0x as long as its apical width; apical width of second tergum 2.0–2.4 that of first tergum. Ovipositor relatively short ( Figs 1, 8 ), about as long as length of terminal sternum; ovipositor sheath hairy.

Male. Body length about 8–8.5 mm (n = 6), forewing length about 6.5–7 mm (n = 6). Similar to female, but apical yellow bands on metasomal segments wider than in female ( Figs 9, 10 ); antenna with 27–28 flagellomeres; first flagellomere proportionally slightly longer than in female, nearly 3x as long as its apical width; terminal flagellomere 1.8–2.3x and 1.3–1.7x as long as its basal width for flagellum with 27 and 28 flagellomeres, respectively.

Type series. Holotype: Ƥ (repository: Australian National Insect Collection, CSIRO, Canberra), labeled (slash indicates new line) “ AUSTRALIA, N.S.W. / Cabbage Tree Creek / (along Kings Highway) / 35°34’S, 105°02’E / emerged 10.vii.2004 from / Ropalidia plebeiana nest / kept in laboratory / Nest collected iiiiv.2004 / J. Kojima” and “ HOLOTYPE / female / Arthula plebeja Ubaidillah & Kojima ”. Paratypes: 10 specimens (Australian National Insect Collection, Museum Zoologicum Bogoriense and Natural History Collection of Ibaraki University): 2Ƥ23, same data as holotype; 1Ƥ, “ Australia, N.S.W. / Cabbage Tree Creek / 35°34’S, 105°02’E / 29.ii.2000. J. Kojima”; 1Ƥ13, “ Australia, ATC / Canberra, emerged in vii.2004 / from Ropalidia plebeiana nest / collected in iii-iv 2004 / J. Kojima; 33, “ Australia, NSW / 35°39’S, 105°09’E / 1.9 km in driveway distance / from Batemans Bay in / direction of Canberra / emerged on 16.vii.2004 [12.viii.2004 (for 23)] / from R. plebeiana nests / coll. in iii-iv 2004, J. Kojima.”

Etymology. The specific name, plebeja , is a Latin adjective meaning “plebeian,” used after the specific name of the host paper wasp, Icaria plebeja de Saussure, 1863, non 1862 (= Ropalidia plebeiana Richards, 1978 ).

Remarks. This species is similar to A. flavofasciata in the shape of the antenna and metasoma, both of which seem to be key characters to distinguish Arthula species, but can be easily distinguished from A. flavofasciata by having the first metasomal tergum weakly widened posteriorly (apical width about 1.5x as wide as the basal width vs. about 2.0x in A. flavofasciata ), and the dorsal surface of the same tergum in profile more or less smoothly curved (angled in A. flavofasciata ). Arthula plebeja is distinctly different from the other two species, A. brunneocornis and A. formosanus , by the female antenna having the smallest number of flagellomeres (23–24 in A. plebeja vs. 26–27 in A. brunneocornis vs. 28 in A. formosanus ), and in the proportionally shorter first two metasomal segments (in A. brunneocornis and A. formosanus , the first tergum much elongated and the second tergum distinctly longer than the apical width).

Figures

FIGURES 1 – 10. Arthula plebeja Ubaidillah and Kojima, sp. nov. 1 – 8, female, holotype. 9 – 10, male, paratype. 1 and 9, habitus. 2, head, frontal view. 3, head, dorsal view. 4, mandibles. 5, forewing. 6, first and second metasomal segments, lateral view; 7, first and second metasomal segments, dorsal view. 8 and 10, apical part of metasoma, lateral view (OV, ovipositor). Scale bars: 1 mm, but 5 mm for figures 1 and 9.