Megarhyssa gratiosa Khalaim & Ruíz-Cancino, 2013

Khalaim, A. I. & Ruíz-Cancino, E., 2013, A new species of Megarhyssa Ashmead (Hymenoptera: Ichneumonidae: Rhyssinae) from tropical Mexico with a key to Mexican species, Zootaxa 3619 (2), pp. 195-200 : 197

Megarhyssa gratiosa Khalaim & Ruíz-Cancino , sp. nov.

Figs 1–8 .

Material examined. Holotype female ( EMEC) “ Mexico, Chiapas, 27 mi. [= 43.5 km] N. Ocozocoautla [de Espinosa], 21 July, 1965”, “D.R. Pauson collr.”, “California State Univ., Long Beach 1996 Donation Calif. Acad. Sci.”

Description. Female. Body length including ovipositor about 105 mm, without ovipositor 28 mm. Fore wing length 23 mm.

Head, in dorsal view, slightly prominent just behind eyes and then roundly narrowed ( Fig. 5 ). Antenna with 55–56 flagellomeres; flagellum almost 1.1 × as long as fore wing; flagellomeres 1–5 combined 1.4 × as long as hind basitarsus. Malar space 0.57 × as long as basal width of mandible ( Fig. 4 ). Mandible robust, longitudinally striate in basal half; upper tooth roundly pointed, longer than lower tooth; lower tooth obtuse, much broader than upper tooth, uniformly rounded ventrally. Clypeus with strong transverse carinae. Labrum greatly exposed, widely rounded ventrally. Face with large and very dense (sometimes almost touching) punctures. Frons with high longitudinal crest between antennal sockets. Vertex and gena smooth and shining, with fine and sparse punctures; lower part of gena with distinct punctures and shallow longitudinal striae. Occipital carina developed only ventrally, completely absent dorsally and dorsolaterally.

Mesosoma predominantly smooth, partly finely punctate. Mesopleuron centrally with fine and dense setiferous punctures, ventrolateraly impunctate. Scutellum with two arcuate transverse wrinkles in its posterior half. Postscutellum with one arcuate transverse wrinkle. Metapleuron anteriorly sparsely punctate. Pleural carina well developed. Propodeum smooth, virtually impunctate, with one complete transverse carina, complete lateral longitudinal carina and lateromedian longitudinal carina present as vestige only anteriorly in front of transverse carina; area basalis slightly transverse, distinctly impressed. Fore wing with large areolet with moderately short stalk anteriorly (anterior corner of areolet not touching R; Fig. 8 ). Vein 2 m-cu slightly arcuate toward base of the wing. Hind wing with distal abscissa of Cu 1 meeting cu-a very close to M, almost touching this vein ( Fig. 8 ). Hind coxa at base ventrally with conspicuous crest. First tergite 2.2 × as long as posteriorly broad. Apical edge of first sternite slightly in front of spiracle of first tergite. Laterotergites 1–5 large. First and second tergites smooth, weakly polished, impunctate, mostly glabrous. Tergites 3+ more or less smooth, impunctate, with short pubescence. Ovipositor sheath almost 3.4 × as long as fore wing and 2.8 × as long as body ( Fig. 1 ).

Colour pattern. Head yellow, with a pair of black lateral marks on frons, black interocellar area and with a blackish mark extending from lateral ocellus to margin of eye. Antenna black, scape and pedicel yellowish beneath, flagellum basally brownish, with a contrast subapical yellow-orange band that covers flagellomeres about 33 to 49. Mandible yellow in basal half and black in apical half. Vertex posteromedially and upper part of occiput black.

Mesosoma yellow with black markings ( Figs 4, 5 ). Anteromedian part and narrowly hind margin of pronotum, large O-shaped mark on mesoscutum, scuto-scutellar groove, about 70% of prepectus, dorsoposterior mark on mesopleuron, anterior margin of metapleuron and its lower part in anterior 0.6, area around the propodeal spiracle, dorsobasal part and median longitudinal stripe on propodeum black.

Wings hyaline, fore wing with conspicuous dark spot at apex of radial cell ( Fig. 8 ). Fore and mid legs predominantly yellow. Mid leg with femur and basitarsus slightly reddish, tarsomeres 2–4 fuscous and the apical tarsomere black ( Fig. 3 ). Hind leg with coxa yellow basally to reddish brown apically, first trochanter reddish brown, second trochanter and femur red-brown, tibia and tarsomeres 1–4 reddish brown, and apical tarsomere black ( Fig. 3 ).

Metasoma yellow with broad longitudinal dorsal black mark extending from its base to apex ( Figs 6, 7 ); tergites 1–6 laterally narrowly black on crease separating laterotergites, and tergite 7 with oblique blackish mark from its base to spiracle ( Fig. 6 ). Ovipositor black with reddish tinge; sheath black with extreme apex (less than 0.02 of entire sheath length) yellow.

Male. Unknown.

Etymology. From the Latin gratiosa (agreeable, enjoying favor).

Distribution. Southern Mexico (Chiapas). Southernmost record of the genus in the New World.

Comments. The new species may easily be recognized by the characteristic colour pattern of the metasoma which is yellow with broad dorsal black stripe extending along its entire length ( Fig. 7 ), and the ovipositor which is longer than in the other two Mexican species ( Fig. 1 ). It also differs from M. verae and M. macrura by having a hyaline fore wing with a conspicuous dark spot at apex of the radial cell ( Fig. 8 ), and from M. verae , also in having 56 flagellomeres (only 36 flagellomeres in M. verae ) and a shorter malar space.

Figures

FIGURE 8. Megarhyssa gratiosa sp. nov., holotype, Ƥ: wings, dorsal.

FIGURES 1 – 3. Megarhyssa gratiosa sp. nov., holotype, Ƥ: 1 — habitus, dorsal; 2 — antenna, dorso-lateral; 3 — mid and hind legs, ventro-lateral.

FIGURES 4 – 7. Megarhyssa gratiosa sp. nov., holotype, Ƥ: 4 — head and mesosoma, left; 5 — head and mesosoma, dorsal; 6 — metasoma, left; 7 — metasoma, dorsal.