Orthocentrus rhombifer, Humala, 2019

Humala, Andrei E., 2019, Mexican species of the genus Orthocentrus (Hymenoptera, Ichneumonidae: Orthocentrinae), Zootaxa 4709 (1), pp. 1-83 : 72-73

Orthocentrus rhombifer sp. nov.

( Figs 6 E , 11 E , 14 N , 17 N , 24 )

Material examined. Holotype ♀: México, Veracruz; Est. Biol. Trop. Los Tuxtlas, C 6, MT-II, 246 m, N 18°35ʹ07.6″, W 95°04ʹ47.5″, label with date missing, leg. M. Madora ( UNAM).

Description. Female. Fore wing length 2.6 mm.

Face medially 1.2 × as wide as high; face papillate, eyes glabrous, dorsal ridge of face inbetween antennal sockets without a median prominence; face in profile nearly straight, slightly rounded especially dorsally, edge of clypeus lightly impressed, antennal sockets on a shelf but shelf not particularly high (Hw/Fp = 7.6); subocular sulcus present, almost straight; maxillary palp reaching to about epicnemial carina. In dorsal view, head posteriorly slightly concave, temples steeply narrowing and in lateral sides eyes reach occiput, about 0.1 × eye width, posterior ocellus separated from eye by 1.3 × ocellar diameter, anterior ocellus separated from eye by 1.9 × ocellar diameter, lacking ocellar-ocular grooves. Minimum distance between antennal sockets about half diameter of socket; antenna slender, about as long as body, with 31 elongate flagellomeres which gradually shortening towards apex; basal flagellomere 3.5 × as long as wide and about as long as 3/4 scape; scape in frontal view straight on lateral surface, slightly convex on inner surface.

Mesosoma smooth and polished, mesoscutum lacking notauli, very finely pustulate with hairs; in profile, scutellum somewhat high, metapleuron slightly convex; propodeum with posterior transverse carina present between lateral longitudinal carinae, median longitudinal carinae complete, lateral longitudinal carinae reach spiracles, spiracles small. Pleural carinae indistinct anteriorly.

Legs moderately broad; coxae polished, femora coriaceous, tibiae and tarsi granulate-coriaceous; hind coxa 1.1 × as long as first tergite, hind femur 3.0 × as long as high, hind tibia stout, 3.6 × as long as apically wide; tibiae without clear spine-like setae; hind claws enlarged.

Wings not particularly narrow; fore wing with areolet open, vein Rs bent outwards; pterostigma asymmetrical, Rs+2 r meeting stigma at apical third; nervulus strongly postfurcal, oblique; hind wing with nervellus indistinctly intercepted at lower third.

First tergite apically widening, 1.4 × as long as apically wide; coriaceous, longitudinally striate, with two posteriorly almost complete median longitudinal carinae, with transverse impressions originating at about middle of tergite, sloping posteriorly, not meeting centrally. Second tergite 0.9 × as long as apically wide; longitudinally striate, with central rhombic area bounded by strong anterolateral diagonal impressions connected with angular posterior transverse groove; basal thyridia oval-rectangular, contrastingly coloured, second thyridia rounded raised and smooth areas at about middle of tergite inside of rhombic area. Third tergite with particularly anterior edge impressed and smoothly coriaceous. Remaining tergites smooth and almost polished, with coriaceous microsculpture. Ovipositor not visible; probably thin and straight; sheaths with setae similar to other metasomal setae.

Body largely setose except eyes, pronotum, mesopleuron and metapleuron; setae very scattered on propodeum, basal tergites, and posterior sides of coxae.

Yellow except antennae, interocellar area, temples partly, occiput, pronotum anterodorsally, metapleuron, propodeum, metasoma except sternites and posterior corners and apical margin of second tergite, thyridia and third tergite; marks on hind coxa apically, hind femur in apical half and narrow basal band of hind tibia, brown; mouthparts, propleuron, tegula, fore and mid coxae, trochanters, trochantelli, sternites, creamy.

Male. Unknown.

Biology. Hosts unknown.

Distribution. Mexico (Veracruz).

Etymology. Named after the rhombic area on second tergite.

Comments. Compared with the other species that have completely papillate face, antennal sockets on a distinct but low shelf, and glabrous eyes, areolet open and pterostigma asymmetrical, unlike in O. elongatus , O. hidalgoensis , O. longiventris and O. ungularis ; temples extremely narrow and second tergite with central rhombic area, unlike in O. flavoorbitalis .

Figures

FIGURE 6. Lateral views: Orthocentrus ungularis species-group. A: elongatus, B: flavoorbitalis, C: hidalgoensis, D: longiventris, E: rhombifer, F: ungularis. Scale 1.0 mm.

FIGURE 11. Faces: Orthocentrus ungularis species-group.A: elongatus, B: flavoorbitalis, C: hidalgoensis, D: longiventris, E: rhombifer, F: ungularis. Scale 0.2 mm.

FIGURE 14. Heads in dorsal view: Orthocentrus maculae and O. ungularis species-groups. A: brevicornis, B: coronadoae, C: latus, D: lopezi, E: rufipleuris, F: scutellatus, G: similis, H: tergalis, I: varicolor, J: elongatus, K: flavoorbitalis, L: hidalgoensis, M: longiventris, N: rhombifer, O: ungularis. Scale 0.2 mm.

FIGURE 17. Basal tergites: Orthocentrus maculae and O. ungularis species-groups. A: brevicornis, B: coronadoae, C: latus, D: lopezi, E: rufipleuris, F: scutellatus, G: similis, H: tergalis, I: varicolor, J: elongatus, K: flavoorbitalis, L: hidalgoensis, M: longiventris, N: rhombifer, O: ungularis. Scale 0.2 mm.

FIGURE 24. Distribution map of Orthocentrus in Mexico. O. elongatus, O. flavoorbitalis, O. longiventris, O. rhombifer