Labium walkeri Turner & Waterson, 1920

Royo, José Manuel & Bordera, Santiago, 2024, Description of the female of Labium walkeri Turner & Waterson, 1920 from Australia with new distribution data of L. montivagum (Hymenoptera, Ichneumonidae, Labeninae), Zootaxa 5471 (2), pp. 253-260 : 254-257

Labium walkeri Turner & Waterson, 1920

( Figs 1 , 2 , 4 )

Diagnosis. Labium walkeri can be distinguished from all other Australian species by the following characters in combination: antenna with 22–25 flagellomeres ( Fig. 1A , 2H ); face as broad as long ( Fig. 1B , 2B ); clypeus slightly convex, in lateral view in the same plane of face, with fine and moderately dense setiferous punctures; occipital carina complete. Fore wing with vein 2 m-cu only weakly bent in the middle, not abruptly angled ( Fig. 1F , 2E ) as in other species of the genus. Hind wing with distal abscissa of CU missing; cu-a + first abscissa of CU straight or slightly curved, not angled ( Fig. 1A , 2G ).

Description. Female: Body length 5.15–5.4 mm. Fore wing length 3.6–4.0 mm.

Head. In dorsal view 2.06–2.10 × as wide as long; clypeus 2.0–2.2 × as broad as high, clypeal sulcus slightly insinuated, less so in the middle than at the sides, face and clypeus slightly convex ( Fig. 1B ), in lateral view in the same plane, with fine and moderately dense setiferous punctures; face as broad as long ( Fig. 1B ); malar space 0.58–0.70 × as long as basal width of mandible; eyes somewhat emarginate above the antennal insertions; vertex and frons smooth with sparse setiferous punctures; gena smooth, in dorsal view, rounded, 0.62–0.72 × as long as eye; posterior ocellus separated from eye 1.37–1.58 × its own maximum diameter; distance between posterior ocelli 1.18–1.33 × maximum diameter of posterior ocellus; occipital carina complete. Antenna with 22–24 flagellar segments ( Fig. 1A ); second flagellar segment 0.9–1.0 × the length of first one.

Mesosoma. Pronotum smooth and shiny with weak rugae ventrally ( Fig. 1D ); mesoscutum smooth and shiny very scarcely punctate ( Fig. 1E ), middle lobe of mesonotum not prominent; notauli short 0.13–0.16 × the length of mesoscutum; mesopleuron smooth and shiny with sparse setiferous punctures ( Fig. 1D ), mesopleural furrow crenulate, epicnemial carina reaching half length of pronotum, sternaulus absent; metapleuron entirely smooth and shiny, juxtacoxal carina strong and well defined posteriorly, replaced by some rugae anteriorly, submetapleural carina expanded anteriorly in a prominent lobe ( Fig. 1D ). Propodeum ( Fig. 1C ) mostly smooth and shiny, posterior areas slightly rugulose; lateral areas with long and moderately dense setae; area superomedia hexagonal, 1.27–1.5 × wider than long, slightly broader anteriorly than posteriorly, clearly separated from the petiolar area and basal area, sometimes narrowly opened to basal area in the mid part; area basalis short and broad. Hind leg with trochanter swollen dorsally ( Fig. 1A ); femur 2.57–2.75 × as long as high. Fore wing ( Fig. 1F ) with areolet pentagonal, 1.15–1.2 × as broad as long; abscissa of M between 3 rs-m and 2 m-cu much shorter than abscissa between 2 rs-m and 2 m-cu; vein 2 m-cu feebly bent in the middle; vein 1 cu-a conspicuously postfurcal to M&Rs. Hind wing with distal abscissa of CU absent; cu-a + first abscissa of CU straight or slightly curved, not angled ( Fig. 1A ).

Metasoma. Tergite I 1.8–1.9 × as long as posteriorly broad, smooth and shiny with subbasal tooth and prominent spiracular area ( Fig. 1E ); tergite II 0.62–0.76 × as long as posteriorly broad, smooth and shiny, with scarcely short setae; tergites III–VII densely and finely punctate with pubescent setae ( Fig. 1G ); ovipositor not reaching the end of metasoma, short and straight ( Fig. 1G ).

Colouration: Black and dark orange ( Fig. 1 ); head dark brown to black, mandible (except dark brown apex), labrum, clypeus, malar space, face, frontal, and genal orbits narrowly (except dorsal part), white cream. Antenna dark brown, light brown ventrally, scapus whitish ventrally. Mesosoma mostly dark orange; tegula, scuto-scutellar groove, axillae, juxtacoxal area and narrowly the dorsal part of mesopleuron, dark brown; posterior part of scutellum, postscutellum, posterior spot on metapleuron, and subtegular ridge, yellow cream. Fore and mid legs light brown posteriorly, white cream anteriorly; proximal tarsi white cream, distal tarsi dark brown. Hind leg mostly dark brown; base of coxa and lateral spots on femur, orange; mid part of tibia white cream. Wings hyaline. Metasoma dark brown; tergites I–III with posterior margin white.

Male: Body length 4.8–5.84 mm. Fore wing 3.6–4 mm.

Head. In dorsal view 1.71–1.6 × as wide as long; clypeus 2.0–2.1 × as broad as long, clypeal sulcus distinct, less so in the middle than at the sides; face and clypeus slightly convex, with fine and moderately dense setiferous punctures ( Fig. 2B ); occipital carina complete; malar space 0.54–0.71 × as long as basal width of mandible; eyes somewhat emarginate above the antennal sockets ( Fig. 2B ); vertex and front smooth and shiny, with sparse setiferous punctures ( Fig. 2G ); gena smooth with moderately dense setiferous punctures, rounded in dorsal view, 0.5–0.6 × as long as eye; posterior ocellus separated from eye about 1.42–1.14 × its own maximum diameter; distance between posterior ocelli 1.14–0.85 × the maximum diameter of posterior ocellus.Antenna with 22–25 flagellar segments, the second flagellar segment 0.9–1.0 × the length of first one ( Fig. 2H ).

Mesosoma. Pronotum mostly smooth and shiny, with weak rugae ventrally ( Fig. 2F ); mesoscutum ( Fig. 2G ) smooth and shiny with very scarcely setiferous punctures, denser anteriorly and laterally; middle lobe of mesonotum not prominent; notauli short 0.16–0.2 × the length of mesoscutum; mesopleuron ( Fig. 2F ) smooth and shiny with sparse setiferous punctures, mesopleural furrow crenulate, epicnemial carina reaching half length of pronotum, sternaulus absent; metapleuron entirely smooth and shiny, juxtacoxal carina complete, submetapleural carina expanded anteriorly into a prominent lobe. Propodeum ( Fig. 2D ) mostly smooth and shiny, posterior areas slightly rugulose; lateral areas somewhat rugulose with long and moderately dense setae; area superomedia 1.30 × as wide as long, much wider anteriorly than posteriorly, hexagonal, separated from petiolar area, narrowly opened to basal area in the mid part; area basalis short and broad. Hind leg with trochanter swollen dorsally ( Fig. 2C ), femur 3.5–3.75 × as long as high. Fore wing ( Fig. 2E ) with areolet pentagonal, 1.1–1.15 × as broad as high; abscissa of M between 3 rs-m and 2 m-cu much shorter than abscissa between 2 rs-m and 2 m-cu; vein 2 m-cu feebly bent in the middle; vein 1 cu-a conspicuously postfurcal to M&Rs. Hind wing ( Fig. 2E ) with distal abscissa CU absent; cu-a + first abscissa of CU straight or slightly curved, not angled.

Metasoma. Tergite I ( Fig. 2G ) 2.0 –2.6 × as long as posteriorly broad, smooth and shiny without subbasal tooth, with a prominent spiracular area; tergite II 0.69–0.7 × as long as posteriorly broad, smooth and shiny, with very sparce setiferous punctures; tergites III–VII finely punctate with short dense setae ( Fig. 2G ).

Colouration: Black and brownish ( Fig. 2 ); head black, mandible (except dark brown apex), labrum, clypeus, malar space, face, frontal orbits, and genal orbits narrowly (except dorsal part), white cream. Antenna dark brown dorsally, flagellum yellow ventrally except first flagellar segment, scapus whitish ventrally. Mesosoma black; tegula, scutellum, postscutellum, subtegular ridge, weak spot on mid anterior part of mesopleuron, and posterior spot on metapleuron, yellow cream. Fore and mid legs mostly white cream; distal tarsi slightly brownish. Hind leg mostly dark brown; hind coxa black, posterior edge of coxa, trochanter, trochantellus and mid part of tibia white, lateral spots on femur, orange. Wings hyaline. Metasoma dark brown; tergite I black, tergites I–V with posterior margin white.

Material examined: 1 ♂, holotype, Hobart , Tasmania, summer 1891, NHMUK010636268 (Images from NHM Data Portal) ; 2 ♂♂, 2 ♀♀, Australia, Victoria Tylden South , 3444, 4.III.2016 / 18.III.2016, Bonavia 2, Malaise Trap, Leg. A. Campoy ; 1 ♀, Australia, Victoria, Musk , 25.II.2016 / 4.III.2016, Rza 1, Malaise Trap, leg. A. Campoy ( CEUA) .

Distribution: Australia (Tasmania and Victoria) ( Fig. 4 ).

Remarks: The species L. walkeri , together with L. centrale Turner & Waterson, 1920, L. raymenti Cushman, 1934, and L. brevicorne Turner & Waterson, 1920, can be distinguished from other Australian species by antennae with fewer than 30 flagellomeres (Turner & Waterson, 1920; Cushman, 1934). Furthermore, L walkeri can be distinguished from those four species by fore wing vein 2 m-cu only weakly bent in the middle ( Figs 1F , 2E ), hind wing with vein cu-a + first abscissa of CU straight, distal abscissa of CU absent ( Figs 1A, 1F , 2E ), head dark with yellow markings, and mesosoma black in male and dark orange in female ( Figs. 1–2 ).

Figures

FIGURE 1. Labium walkeri female: A—Habitus (lateral view); B—Head (frontal view); C—Propodeum (dorsal view); D— Head and mesosoma (lateral view); E—Head, mesosoma, and tergites I–II (dorsal view); F—Front wing; G—Metasoma (lateral view). Scale bar: 1 mm (A); 0.5 mm (D–G); 0.2 mm (B–C).

FIGURE 2. Labium walkeri male: A—Habitus (lateral view); B—Head (frontal view); C—Metasoma (lateral view); D— Propodeum (dorsal view); E—Wings; F—Head and mesosoma (lateral view); G—Head, mesosoma and metasoma (dorsal view); H—Flagellum. Scale bar: 1 mm (A, G); 0.5 mm (C, E); 0.3 mm (D, F, H); 0.2 mm (B).

FIGURE 4. Distribution maps: A—Labium walkeri; B— Labium montivagum.