Labium dianae, Diaz & Alvarado, 2025

Diaz, Caroll Gamarra & Alvarado, Mabel, 2025, A second species of Labium Brullée 1846 (Hymenoptera, Ichneumonidae, Labeninae) from South America, Zootaxa 5646 (2), pp. 293-296 : 293-295

Labium dianae sp. nov.

( Figs 1 , 2 )

Material examined. Holotype: 1 ♂ “ PERÚ: LA. [Lambayeque] RVS [Refugio de Vida Silvestre] Laquipampa, Higuerón Quemado , 1010m, 06°20’49” S / 79°30’15” O, 20.vii.2023, L. Ramírez ” Paratype: 1 ♂, same data as holotype// MUSMHYM 0810 [leg removed] ( MUSM) .

Diagnosis. Labium dianae can be distinguished from L. wahli by the following characters in combination: antenna with 31 flagellomeres (vs. 35 in male or 36 in female); anterior transverse carina absent between lateromedial longitudinal carinae (vs. present and well defined) ( Fig. 1D ); metasoma with tergites II–III reddish-brown (vs. dark brown with yellowish markings on hind margins ( Fig. 1A ).

Description. Male: Fore wing length 8.3 mm. Female unknown.

Head. Labrum strongly exposed and large, 0.7× as long as wide; clypeus 2.9× as long as wide, clypeal sulcus insinuated, less so in the middle than at sides, face and clypeus slightly convex ( Fig. 1B ), with fine and moderately dense setiferous punctures; face wider than long, malar space 0.25× as long as basal width of mandible; mandible elongate, upper tooth smaller than lower tooth; eyes slightly emarginate above the antennal insertions; vertex and frons smooth with sparse setiferous punctures; gena smooth, in dorsal view, rounded; posterior ocellus separated from eye 1.5× its own maximum diameter; distance between posterior ocelli 0.7× maximum diameter of posterior ocellus; occipital carina complete. Antenna with 31 flagellomeres ( Fig. 1A ).

Mesosoma . Pronotum smooth and shiny with weak rugae ventrally ( Fig. 1E ), epomia strong, sharp and slightly curved; mesoscutum shiny and with parapsidal furrows ( Fig. 1E ), middle lobe of mesonotum not prominent; notauli faint; mesopleuron smooth and shiny with numerous setiferous punctures ( Fig. 1E ), mesopleural furrow crenulate, epicnemial carina reaching about lower 0.4 of pronotum, sternaulus short and postpectal carina absent; metapleuron entirely smooth and shiny with numerous setiferous punctures, submetapleural carina expanded anteriorly in a prominent lobe which overlaps base of mid coxa ( Fig. 1E ). Propodeum ( Fig. 1D ) smooth and shiny anteriorly to posterior transverse carina and posteriorly rugulose; area superomedia hexagonal 1.1× longer than wider, slightly broader posteriorly, anterior transverse carina absent between lateromedial longitudinal carinas (only present as lateral stubs); area basalis short and broad. Hind leg with trochanter swollen dorsally ( Fig. 1A ); femur 2.9× as long as wide. Fore wing with areolet pentagonal, 2.5× 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 slightly angled in the middle; vein 1 cu-a interstitial to M&Rs. Hind wing with distal abscissa CU present; cu-a + first abscissa of CU angled; with 7 hamuli.

Metasoma. Tergite I 2.5× as long as posteriorly broad, striate before spiracle and smooth and shiny after spiracle, without subbasal tooth, with a prominent spiracular area, and lateromedian carinae reaching to about 0.6× as length of tergite ( Fig. 1E ); tergite II 0.9× as long as posteriorly broad, smooth and shiny, with scarcely short setae; tergites III–VII densely and finely punctate with pubescent setae ( Fig. 1A ).

Colouration. Head ( Fig. 1A ) predominantly black, except mandible (although teeth dark brown), labrum, palpi, clypeus, face, and frontal orbit yellow; genal orbit, dorsally, brownish. Antenna predominantly brown, scape (apically yellow) and flagellomere yellowish ventrally (although first flagellomere on basal half brown). Mesosoma predominantly black; tegula, humeral plate, a small longitudinal lateral mark on mesoscutum, scutellum, postscutellum, posterodorsal corner of pronotum, subalar prominence, and anterodorsal corner of mesopleuron yellow. Fore and mid legs with coxae black, trochanter lateroventrally yellow and dorsally brown, trochantellus, tibia and tarsomere yellow, and femur laterodorsally reddish-brown and ventrally brown. Hind leg with coxa black; trochanter and trochantellus brown but distally yellow; femur reddish-brown laterally but basally, apically, ventrally and dorsally brown; tibia yellow grading to dark brown ventrolaterally; basitarsus with basal half yellow and distal half brown; tarsomere 2–5 brown. Wings faintly infumate with pterostigma and veins brown. Metasoma with tergite and sternite I black; tergites II–IV reddish-brown; tergites V–VIII dark brown (but anterocentrally of tergite V reddish-brown).

Variation. The paratype differs from the holotype in the following features: clypeus 3× as long as wide; antenna with 30 flagellomeres; posterior ocellus separated from eye 1.7× its own maximum diameter; hind femur 3× as long as wide; tergite I 2.8 × as long as posteriorly broad; tergite II as long as posteriorly broad; and metasomal tergite IV dark brown.

Comments. Porter (2003) mentioned three morphological differences between the Australian and Neotropical species: the antenna longer and slender, with flagellum only slightly thickened toward apex, notauli lacking a crest at the base, and the second hind tarsomere non-compressed; Labium dianae sp. nov. shares these features previously only known for L. wahli . Although it is uncommon to describe Ichneumonidae species from solely male individuals, we consider that it is worth bringing to light this species as it shows the features mentioned by Porter (2003) and broadens the distribution of the genus in South America.

Distribution and habitat. Labium dianae sp. nov. was collected in a dry forest ( Fig. 2B ) of northwestern Peru ( Fig. 2A ), located in the protected area Refugio de Vida Silvestre Laquipampa, in Lambayeque Department. Previously, in South America, Labium was known only from tropical and subtropical rainforests in eastern Brazil ( Porter 2003), and the record presented here represents the most northern record of the genus in the continent ( Fig. 2B ).

Etymology. The species has been named in honour of Diana Silva, leading Peruvian arachnologist.

Figures

FIGURE 1. Labium dianae sp. nov. male: A. Habitus, holotype (lateral view); B. Head, holotype (frontal view); C. Head, paratype (dorsal view); D. Propodeum, paratype (dorsal view); E. Head, mesosoma and tergite I and II, holotype (lateral view). Scale bar: 1.0 mm.

FIGURE 2. A. Distribution records of Labium species occurring in South America; B. Photograph of the habitat in which Labium dianae sp. nov. was captured (photograph taken by Luis Fernando Ramirez).