Mesoleius Holmgren, 1856

Watanabe, Kyohei, 2024, Taxonomic Study of Japanese Ctenopelmatinae (Hymenoptera, Ichneumonidae), with Descriptions of 22 New Species, Bulletin of the Kanagawa Prefectural Museum (Natural Science) 53, pp. 39-102 : 83-84

Genus Mesoleius Holmgren, 1856

Mesoleius Holmgren, 1856: 69 . Type species: Tryphon aulicus Gravenhorst, 1829 . Designated by Viereck (1912).

Allocritus Förster, 1869: 211 . Type species: Mesoleius tenuiventris Holmgren, 1858 . Designated by Perkins (1962).

Cryptocentrus Walsh, 1873: 156 . Type species: Tryphon submarginatus Cresson, 1864 . Monotypic. Name preoccupied.

Alfkenia Pfankuch, 1906: 89 . Type species: Ichneumon integrator Müller, 1776 . Monotypic.

Mesolius Pfankuch, 1906: 85 . Emendation.

Habrodemus Schmiedeknecht, 1913: 2799 . Type species: Mesoleius elongatus Brischke, 1871 . Included by Schmiedeknecht (1914).

Four species, Mesolei. alekhinoi Kasparyan, 2000 , Mesolei. aulicus ( Gravenhorst, 1829) , Mesolei. nigrans Kasparyan, 2001 , and Mesolei. pyriformis (Ratzeburg, 1852) , have been recorded from Kunashiri Island, Japan, but I have found more than five indeterminate species from Japan. The taxonomic treatment of these species except for a single species requires the additional specimens and comparison with European species. In this study, I describe a new species below.

Preliminary key to Japanese species of Mesoleius (female only) (modified from the key in Kasparyan (2000, 2001))

1. T I longer than 1.8 × as long as maximum width. And/or some metasomal tergites entirely or mainly reddish brown to red. And/or mesopleuron with distinct punctation.

.................................................... Mesoleius spp. -. T I shorter than 1.75 × as long as maximum width. And metasomal tergites black (posterior margins sometimes narrowly tinged with yellow or white). And mesopleuron without distinct punctation, or, when punctation distinct, tibia reddish yellow or dark reddish brown, without white part.

...................................................................... 2 2. Face yellow. Hind coxa and femur red. Mesopleuron and metapleuron black. Ratio of minimum length of gena to basal width of mandible: 0.35–0.45. Area petiolaris of propodeum short and semicircular, its length ca. 0.25 × dorsal length of propodeum. Antenna with 33–36 flagellomeres. Fore wing vein 1cu-a nearly interstitial to vein M&RS. T III usually with reddish triangular spot at base.

................... Mesoleius pyriformis (Ratzeburg, 1852) -. Face black ( Fig. 30B ). Other character states various.

...................................................................... 3 3. Hind tibia uniformly pale reddish brown, red with darkened apex, or less frequently, nearly greyish blackish brown. And/or metasomal sternites mainly white.

.................................................... Mesoleius spp. -. Hind tibia white or whitish yellow medially, blackish brown apically and occasionally at base ( Fig. 30A ). Metasomal sternites mainly black ( Fig. 30A ).

...................................................................... 4 4. Mesopleuron with largely smoothed and shining speculum. Hind leg black with yellow trochantellus and white band of tibia. Ratio of minimum length of gena to basal width of mandible: 0.35. Antenna with 35 flagellomeres. T I 1.6 × as long as maximum width. Fore wing 6.8 mm.

........................ Mesoleius nigrans Kasparyan, 2001 -. Mesopleuron without smooth area or with very small smooth area (its size about as long as spiracle of propodeum: Fig. 30D ). Other character states various.

...................................................................... 5 5. Hind coxa and trochanter red. Hind femur red to blackish brown. Ratio of minimum length of gena to basal width of mandible: 0.2–0.35. Antenna with 31–41 flagellomeres. T I 1.4–1.66 × as long as maximum width. .................... Mesoleius aulicus ( Gravenhorst, 1829) -. Hind coxa, trochanter, and femur black ( Fig. 30A ). Ratio of minimum length of gena to basal width of mandible: 0.35–0.45. Other character states various.

...................................................................... 6 6. Clypeus brown, slightly yellow at sides and lower margin. T I 1.14 × as long as maximum width.Antenna with 36 flagellomeres. Small species, fore wing length 8.4 mm.

...................... Mesoleius alekhinoi Kasparyan, 2000 -. Clypeus entirely yellow ( Fig. 30B ). T I 1.4–1.5 × as long as maximum width. Antenna with 42 flagellomeres. Large species, fore wing length 10.1–11.0 mm. ................................... Mesoleius morishitai sp. nov.

Figures

Fig. 30.Mesoleius morishitai sp. nov. (KPM-NK 84966, holotype, female) ―A: lateral habitus; B: head, frontal view; C: mesopleuron; D: propodeum, dorso-lateral view.