Torymus acutissimus Matsuo, 2020

Matsuo, Kazunori, 2020, A revision of Japanese Torymus Dalman (Hymenoptera: Torymidae), Zootaxa 4758 (3), pp. 401-441 : 411-412

Torymus acutissimus Matsuo n. sp.

Figs 1c , 5 e–f, 10a–d, 24c

Etymology. The specific name, acutissimus , is derived from the associated plant of this species.

Type material. Holotype: ♀ ( BLKU), emerged on May 2010 from an unidentified gall midge that induces a gall on Quercus acutissima collected by K. Matsuo on 18 April 2010 from Azamidai , Kokonoe, Oita, Japan . Paratypes: 5 ♀ and 4 ♂, same data as the holotype ( BLKU) ; 1 ♂, emerged on 5 May 2009 from an unidentified gall midge that induces a gall on Quercus acutissima collected by N. Wachi on 11 April 2009 from Azamidai , Kokonoe, Oita, Japan ( BLKU) ; 1 ♂, emerged on 14 May 2008 from an unidentified gall midge that induces a gall on Quercus acutissima collected by Y. Abe on 11 May 2008 from Jizoubaru , Kokonoe, Oita ( BLKU) . Other specimens: 5 ♀, emerged on 5 May 2009 from an unidentified gall midge that induces a gall on Quercus acutissima collected by N. Wachi on 11 April 2009 from Azamidai , Kokonoe, Oita, Japan ( BLKU) .

Description. Female. Body length excluding ovipositor sheath 2.2–2.4 mm. Head green. Scape yellowish brown but darker apically; pedicel and flagellum brown. Mesosoma green. Fore wing hyaline. Fore and mid coxae yellow; hind coxa concolorous with mesosoma; all femora and tibiae yellow. Metasoma green ( Fig. 1c ).

Head 1.8–1.9× as wide as long in dorsal view; temple 0.2× as long as dorsal length of eye; POL 2.2–2.3× OOL; OOL 1.1–1.3× OD. Head 1.2× as wide as high in frontal view ( Fig. 10a ); eyes separated by 1.1× their height; malar space 0.4× height of eye; mouth 1.8× malar space; clypeus with apical margin produced, truncate medially.Antenna strongly clavate ( Fig. 5e ); scape 0.6–0.7× as long as height of eye, not reaching anterior ocellus; combined length of pedicel and flagellum 1.1–1.3× width of head; pedicel 1.3–1.5× as long as wide; anellus 1.1–1.3× as wide as long; F1 1.1–1.3× as long as wide, a little shorter than F2, with one or two sensilla; F2 1.1–1.3× as long as wide; F3 1.0–1.1× as long as wide; F4 0.8–1.0× as long as wide; F5 0.8–0.9× as long as wide; F6 0.6–0.7× as long as wide; F7 0.6× as long as wide; each funicular segment beyond F1 bearing longitudinal sensilla arranged in one row; C3 with a small tuft of micropilosity beneath.

Mesosoma 1.8–1.9× as long as wide; mesoscutum ( Fig. 10b ) with small piliferous punctures; mesoscutum reticulate; notaulus shallow; scutellum ( Fig. 10c ) 1.3–1.5× as long as wide, sculptured as posterior part of mesoscutum; frenal line absent; frenal area indicated by a difference in sculpture from the rest of scutellum, smoother and glabrous toward apex; dorsellum without median carina; propodeum ( Fig. 10d ) with superficial reticulation; lower mesepimeron 1.1–1.3× as long as wide. Fore wing ( Fig. 24c ) 2.5–2.6× as long as wide; costal cell 9.0–9.2× as long as wide, on upper surface with a setal row in distal 1/3, on lower surface with a setal row which is sparse medially and with scattered setae; basal cell closed, with a few setae; cubital setal line present; basal setal line present; speculum opened below; relative lengths of marginal vein: postmarginal vein: stigmal vein=8.4: 2.2: 1.0. Hind coxa 2.2–2.3× as long as wide, with dorsal carina basally; dorsal surface of hind coxa bare in basal half; hind femur 4.0–4.4× as long as wide; hind tibia with longer spur 1.1–1.2× as long as width of hind tibia, 0.3–0.4× length of basitarsus; hind tibia with shorter spur small, 0.3× length of longer spur.

Metasoma as long as mesosoma; posterior margin of metasomal tergum five entire; tip of hypopygium situated at 0.6 length of metasoma; ovipositor sheath as long as mesosoma, 1.8–1.9× as long as hind tibia.

Male. Differs from female as follows. Body length 2.2 mm. Temple 0.3× as long as dorsal length of eye; POL 2.8× OOL. Antenna stouter than that of female ( Fig. 5f ); scape bluish green; anellus transverse, 2.5 as wide as long; F1 0.8× as long as wide; F2–F7 0.8× as long as wide; longitudinal sensilla on each funicular segment arranged in one row. Fore wing 2.2× as long as wide; relative lengths of marginal vein: postmarginal vein: stigmal vein=6.0: 1.9: 1.0. Metasoma with coppery tint.

Distribution. Japan (Kyushu).

Host information. This species is a parasitoid of an unidentified gall midge ( Diptera : Cecidomyiidae ) that induces stem galls on Quercus acutissima Carruth (Fagaceae) (gall photo: fig. 26b, C–077 of Yukawa & Masuda 1996).

Remarks. Females of T. acutissimus are similar to T. pygmaeus Mayr , which is recorded from Austria ( Graham & Gijswijt 1998), by having the following shared features: antenna strongly clavate; F1 a little shorter than F2; ovipositor sheath as long as mesosoma. However, females of T. acutissimus can be distinguished from T. pygmaeus by the following features: F1 with one or two sensilla (lacking sensilla in T. pygmaeus ); frenal area indicated by a difference in sculpture from rest of scutellum (wholly reticulate in T. pygmaeus ); dorsal surface of hind coxa bare in basal half (with a few setae in T. pygmaeus ).

Figures

FIGURE 1 a–d. ♀, lateral view. a, T. achyranthii; b, T. aciculatus; c, T. acutissimus; d, T. angustitemple.

FIGURE 5 a–h. Antenna. a, T. achyranthii ♀; b, T. achyranthii ♂; c, T. aciculatus ♀; d, T. aciculatus ♂; e, T. acutissimus ♀; f, T. acutissimus ♂; g, T. angustitemple ♀; h, T. brevicaudatus ♀. Scale lines 0.25 mm.

FIGURE 10 a–d. T. acutissimus ♀. a, head, frontal view; b, mesoscutum, dorsal view; c, scutellum, dorsal view; d, propodeum, dorsal view.

FIGURE 24 a–h. ♀ fore wing upper surface. a, T. achyranthii; b, T. aciculatus; c, T. acutissimus; d, T. angustitemple; e, T. brevicaudatus; f, T. hirtipennis; g, T. macrops; h, T. matsunagae. Scale lines 0.5 mm.