Heterischnus mexicanus, Claridge, 2021

Claridge, Brandon, 2021, Revision of Nearctic Heterischnus Wesmael, 1859 (Hymenoptera, Ichneumonidae, Ichneumoninae, Phaeogenini), Journal of Hymenoptera Research 85, pp. 57-79 : 57

Heterischnus mexicanus sp. nov.

Figs 10 , 11 , 12

Diagnosis.

Heterischnus mexicanus sp. nov. can be distinguished from all congeners by a combination of the following: 1) flagellomeres 7/8-11/12 dorsally white in female; 2) propodeum densely and coarsely punctate; and 3) longitudinal carinae of propodeum reduced or obsolete with at least lateral longitudinal carina posteriorly obsolete.

Description.

Female (Fig. 10 ). Body length: 7.7-8.4mm; fore wing length: 4.4-4.5 mm.

Color. Head black, except following areas white: mandible except for brown apex, venterolateral corners of clypeus, and small ovoid adjacent to eye in supra-antennal area; clypeus varying from black to brownish-red; supraclypeal area brown in one specimen; flagellum brown, flagellomeres 7/8-11/12 with ventral surfaces white. Mesosoma overall brownish-red; anterior margin of pronotal collar, dorsal margin of lateral area of pronotum, subalar prominence, and tegula, white; following areas can be dark brown to fuscous: dorsal 0.5 of propleuron, more or less all of remaining non-white areas of pronotum, dorsal region of mesopleuron immediately below tegula, posterior margin of mesoscutum, metanotum, dorsal division of metapleuron, and propodeum. Fore and middle legs with coxae, trochanters, and trochantelli white except for: basal 0.5-0.7 of coxae brownish-red ventrally; femora and tibia brownish-red; tarsomeres light brown to brown. Hind leg brownish-red except for: narrow white apical margin of trochanter; tibia dorsally with irregular light brown maculations; and brown tarsomeres. Metasoma varying from completely brown to dark brown, to having median section of T1, and lateral margins of remaining tergites, brownish-red and remaining areas dark brown. Wing: membrane clear; basal 0.2 of wing with veins white, remaining vein sections brown.

Head. Clypeus smooth, dorsally with fine punctures separated by 1.0-1.5 × their diameter becoming less dense ventrally; ventral margin medially straight and with blunted or obsolete sublateral apices. Supraclypeal area rugulose-punctate with punctures separated by 0.5-1.2 × their diameter becoming sparser laterally. Gena smooth, finely punctate with punctures separated by 0.5-1.5 × their diameter. Malar space 1.5-1.8 × basal mandibular width. Supra-antennal area smooth, coarsely punctate with punctures separated by 0.2-0.5 × their diameter. Vertex smooth, with coarse punctures separated by 0.5-2.0 × their diameter. Antenna with 31-33 flagellomeres.

Mesosoma. Mesonotum smooth with coarse punctures separated by 0.5-1.0 × their diameter. Scutellum smooth, coarsely punctate with punctures separated by 0.5-1.0 × their diameter. Mesopleuron coarsely punctate with punctures separated by 0.2-0.5 × their diameter. Speculum smooth, punctation varying between impunctate to coarsely punctate dorsally. Ventral division of metapleuron coarsely punctate with punctures separated by 0.1-0.3 × their diameter. Dorsal division of metapleuron varying from smooth to sparsely and finely punctate. Propodeum coarsely punctate with punctures separated by 0.1-0.3 × their diameter. Posterior transverse carina and pleural carina present; lateral longitudinal carina absent; remainder of carinae reduced and varying from obsolete to subobsolete medially. Tarsal claws simple.

Metasoma. Postpetiole varying from punctate to granulate. T2 length 1.3-1.4 × posterior width. T2-7 granulate with dense shallow, punctures becoming sparser and indistinct posteriorly. Gastrocoelus granulate. Thyridium distant from T2 anterior margin by 0.8-1.2 × thyridial length.

Male (Fig. 11 ). Body length 7.0-7.3 mm; fore wing length: 3.9-4.4 mm. As in female, except for: UCDC specimen with small yellowish-white triangular mark between clypeus and ventral corner of eye; clypeus yellowish-white except dark brown ventral margin; apical 0.3 of hind tibia brown. In the Big Bend, Texas specimen hind tibia entirely brown.

Material examined.

Holotype: Mexico • ♀; Coahuila, 6 mi. west of Saltillo ; 21.vii.1972; B. & C. Dasch; EMUSENT00000197.

Paratypes: Mexico • 4♂; same collection data as holotype; 20-22.vii.1972; B. & C. Dasch; EMUSENT00000162, EMUSENT000000346, EMUSENT000000326, EMUSENT00000509 • 1♀; Puebla, 30 mi. SW of Tehuacán; 6800 ft; 12.x.1968; R. H., E. M. Painter; EMUSENT00000692 . USA • 1♀; Arizona; Portal , 28.viii.1974; H. & M. Townes; EMUS0000273 • 1♀; same data as preceding; 6.ix.1987; EMUSENT00000272 • 1♂; Texas Big Bend; 5000 ft.; 10.viii.1975; S. & J. Peck; EMUSENT00000361 • 1♂, 1♀; Texas, Government Springs, Grapevine Hills, Big Bend National Park; 5000 ft.; 1.ix.1971; E. E. Grissell & R. F. Denno; UCDC • 1♀; "Ex-chrysanthemum cut flws. fr. Mexico at El Paso"; 1.xi.1963; C. Overmiller; USNM .

Distribution and biology.

Heterischnus mexicanus sp. nov. is the southernmost ranging Heterischnus species in the New World. Its range spans from the southern border of the USA in Arizona and Texas south to central Mexico in Tehuacán (Fig. 11 ). Records indicate that adults are active from late July to October and are likely active later in the year in the southern portion of its range as the latter date is from Tehuacán, Mexico. No host records are known for H. mexicanus .

Comments.

As in H. coloradensis and H. huardi , a few specimens of H. mexicanus sp. nov. show an overall lighter coloration.

Etymology.

This species epithet refers to its distribution, the majority of which is in Mexico.

Figures

Figure 10. Heterischnus mexicanus sp. nov., holotype female A habitus B mesosoma, lateral view C head, frontal view D head, dorsal view E propodeum, dorsolateral view. Scale bars: 5.0 mm (A); 1.0 mm (B-E).

Figure 11. Heterischnus mexicanus sp. nov., paratype male (Mexico: Saltillo) A habitus B head, frontal view. Scale bars: 5.0 mm (A); 1.0 mm (B).

Figure 12. Distribution of Heterischnus mexicanus sp. nov.