Ischnus coxalis Kasparyan, 2021

Kasparyan, D. R. & López-Ortega, M., 2021, A new species of Ischnus from Mexico (Hymenoptera: Ichneumonidae: Cryptinae: Cryptini), Zoosystematica Rossica (China) 30 (1), pp. 94-100 : 95-99

Ischnus coxalis Kasparyan , sp. nov.

( Figs 1–9)

Holotype. Female; Mexico, State of Veracruz, Xalapa , Unidad de Servicios Bibliotecarios y de Información ( USBI), Malaise trap T1 , September 2017, coll. M. López-Ortega ( UNAM).

Paratypes. Mexico, same locality and collector as for holotype: 13 April 2016, 1 male ( UAT) ; 13 July 2016, 1 male ( UNAM) ; November 2016, 1 male ( ZIN) ; December 2016, 1 male ( UNAM) ; July 2017, 1 female ( ZIN) .

Description. Female (holotype). Fore wing 3.8 mm long.

Flagellum with 22 flagellomeres; flagellomeres 1 and 2 combined about 1.3 times as long as maximum diameter of eye. Head in dorsal view strongly and roundly narrowed behind eyes towards occipital carina. Frons evenly and finely granulate, with thin polished median longitudinal stripe ( Fig. 3). Face and malar space coarsely granulate, strongly matt. Malar space about as long as basal mandibular width. Clypeus strongly convex in profile, with narrow polished groove just above sharp lower margin. Occipital carina joining hypostomal carina behind lower corner of mandible at distance 0.3 times the basal mandibular width.

Pronotum with short epomia, laterally evenly granulate, without any rugosity. Notaulus strong, extending to anterior 0.7 of mesoscutum ( Fig. 3). Mesoscutum and scutellum matt, evenly granulate, with sparse indistinct punctures. Scutellum with lateral longitudinal carinae extending at least in its basal half. Mesopleuron distinctly granulate; in upper third of mesopleuron (before speculum) granulae confluent into fine, arched upward longitudinal striation; speculum and epimeron polished ( Fig. 4). Metapleuron and propodeum evenly granulate. Propodeum with only anterior transverse carina; posterior transverse carina entirely absent ( Fig. 5). Fore wing with nervulus interstitial and postnervulus intercepted in its upper 0.4. Hind wing with nervellus intercepted in lower 0.4; brachiella entirely reduced.

First metasomal tergite basally without distinct lateral tooth, but with dorsolateral margin sharp, slightly rounded and weakly protruding (similar to that in males of I. laevifrons ). Metasomal tergites 1–3 evenly granulate, tergites 4 and 5 with shallow granulation, tergites 6–7 subpolished. Postpetiole behind spiracles 1.15 times as long as wide. Second tergite about as long as wide posteriorly, with scarce short setae, with indistinct superficial (though rather large on lateral parts of tergite) punctures. Ovipositor as long as hind tibia; its sheath about 0.7 times as long as hind tibia; apex of ovipositor sagittate ( Fig. 1); tip of upper valve beyond nodus as long as second tarsomere of hind tarsus.

Antenna black with flagellomeres 6–9 dorsally white; scape and pedicel pale reddish brown ventrally, blackish brown dorsally. Head predominantly dull yellowish white; ocellar area black; vertex reddish brown (except for whitish orbits). Mesosoma reddish with yellowish white propleura, anterior and dorsolateral margins of pronotum, anterior margin of mesopleuron, subtegular ridge, tegula and mesosternum; mesosoma with black lateral spots behind base of wings, dorsal part of groove between metanotum and propodeum, and entire metasternum. Pterostigma yellowish brown. All coxae and trochantelli white (hind trochantellus with small black mark anteriorly); hind coxa black at extreme base anteriorly, with large dorsoapical black spot (this spot wider at anterior edge) ( Fig. 4); trochanters white ventrally and darkened dorsally ( Fig. 4). Femora, tibiae and tarsi predominantly pale reddish brown with femora more reddish, tibiae and tarsi more brownish ( Fig. 1). First metasomal segment reddish with basal half of petiole black ( Figs 4 and 5); tergites 2–7 yellowish to pale reddish, with large triangular blackish mark dorsally at base of each tergite ( Figs 1 and 5). All sternites pale yellowish.

Male. Fore wing 4.0– 4.4 mm long; antenna with 24 or 25 flagellomeres; flagellomeres 12 to 14 (or 15) with fine linear tyloids. Coloration distinctly different from that in female: flagellum completely black ( Fig. 9), all metasomal tergites black with white posterior margins ( Fig. 7), all femora predominantly white (hind femur dorsally black, fore and mid femora brownish; Fig. 6). Head and thorax of male whitish (vs. yellowish in female) with black marks stronger, i.e. lateral areas of mesonotum and metanotum sometimes completely black and propodeum before anterior transverse carina with large black median mark or almost completely black. Granulation on frons, mesopleuron and anterior part of propodeum shallower than in female; frons subpolished. All tergites matt, with longer and more distinct pubescence than in female.

Variation. In female paratype, tergites 3–7 blackish in basal 0.7–0.9.

Comparison. Ischnus coxalis sp. nov. is similar to the Nearctic species I. laevifrons as both the species possess the propodeum lacking the posterior transverse carina, smooth frons without median scabrosity, red mesoscutum and propodeum, and are rather small with fore wing length 3.8–6.0 mm. By the combination of the characters listed above, these two species differ clearly from all their New World congeners. Ischnus coxalis sp. nov. can be distinguished from I. laevifrons by the characters listed in Table 1.

The South American species Ischnus leucomelas and I. variegatus are clearly larger than

D.R. Kasparyan & M. López-Ortega. A new species of Ischnus from Mexico the North American species (body length about 10.0 mm vs. 4.0–8.0 mm in the North American species) and differ from I. coxalis sp. nov. also in their colour pattern. The mesosoma of I. leucomelas is predominantly black with white marks and the metasoma has white petiole, while in I. coxalis sp. nov. the mesosoma is predominantly reddish and the petiole is black ( Fig. 4). Ischnus variegatus has the prothorax and mesonotum black, scutellum white, and metasomal tergites tricolourous, i.e. with reddish basal band, black median band and white apex, while in I. coxalis sp. nov. the mesosoma is nearly completely reddish with the scutellum yellowish at the apex and metasomal tergites blackish at base ( Figs 1 and 5).

Remarks. The new species is characterised by a strong sexual dimorphism. Females possess an antennal flagellum with a white band ( Fig. 1), distinctly granulate frons ( Figs 2 and 3), reddish and granulate mesopleuron and mesosternum ( Fig. 4), uniformly reddish hind femur, and metasomal tergites 1–7 predominantly pale reddish with a large blackish basal mark on each tergite ( Figs 1 and 5), while males have an entirely black flagellum ( Fig. 9; in other species of Ischnus ,

D.R. Kasparyan & M. López-Ortega. A new species of Ischnus from Mexico the flagellum is always white-banded both in males and females), polished frons, mesopleuron and mesosternum predominantly whitish and almost entirely polished ( Fig. 6), hind femur whitish ventrally and brown to blackish dorsally ( Fig. 6), and metasomal tergites dorsally blackish with hind margins whitish ( Figs 6 and 7).

Etymology. The species name is a Latin adjective referring to the remarkable coloration of the hind coxae.