P. hyalinus species group sensu Smulyan (1936) and Darling (1996)

Description.

Female. Color: head and body entirely or at least partially brightly iridescent (Fig. 2 A, H).

Head: in anterior view weakly transverse, slightly wider than high, HW / HH 1.2–1.3; slightly wider than pronotum, HW / PW 1.1–1.2. Frontal carina: distinct, extended from posterior margin of median ocellus (Fig. 2 B) to near lower eye margin (Fig. 2 A); in dorsal view narrow near median ocellus. Ocelli: median ocellus in line with lateral ocelli or only slightly advanced (Figs 2 B, 12 G). Eye: slightly shorter than head height, EH / HH 0.6–0.7. Vertex: rounded behind. Occiput: with vertical groove below vertex, with subparallel costulae; occipital carina absent. Malar space (Fig. 2 A): with oblique striae obliterating malar sulcus (Fig. 2 D). Clypeus (Fig. 3 A): weakly transverse to strongly transverse, CW / CH 1.3–1.6; lateral sulci straight or weakly curved, strongly divergent; with small and indistinct tentorial pits; epistomal sulcus concave, deeper and more distinct than lateral sulci; ventral margin concave or nearly flat. Supraclypeal area (Fig. 3 A): subquadrate; shorter and narrower than clypeus, SCH / CH 0.5–0.6. Scape (Figs 3 C – E): length about 0.6 × EH; narrow throughout; pits absent or if present distad covering no more than 0.2 × scape length (Figs 3 D, E). Flagellum (Fig. 3 I): anellus transverse, AL / PL about 0.3; Fu 1 subquadrate, Fu 1 L / Fu 1 W 1.0–1.1; subequal to or slightly longer in length than pedicel, Fu 1 L / PL 1.0–1.3; Fu 2 subquadrate or transverse, Fu 3 – Fu 7 transverse; clava 4 - segmented, C 1–3 as long dorsad as ventrad, with distinct terminal button (C 4).

Mesosoma: slightly longer than wide, ML / MW 1.2–1.3. Pronotum: carinulate (Fig. 2 H); short, PN / MSC about 0.2; shorter along midline, 0.5–0.7 length laterad; anterior margin sharp, all rows of punctures on same plane. Lateral panel of pronotum: without flange (Fig. 4 D) or with flange below level of mesothoracic spiracle in posterior oblique view (Fig. 16 D: arrow); anterior margin sharp, all rows of punctures on same plane. Prepectus: wide and triangular; differentiated from pronotum with distinct suture; ventral strap short, without row of alveolae; central area of lateral panel smooth, with foveae along dorsal and posterior margins. Mesoscutum (Fig. 2 H): midlobe without tubercle; notaulus distinct and continuous, uninterrupted by sculpture of mesoscutum. Mesoscutellum: without tubercle; slightly longer than mesoscutum, SC / MSC 1.2–1.3; strongly vaulted, frenum ventrad and not visible in the dorsal view. Axilla: with axillar shelf (Fig. 2 F). Axillula: elongate and finger-like, AxL / AxH usually 2.0 or greater (Fig. 2 F). Metanotum: short, length 0.4–0.5 × length of propodeum along midline. Propodeum: width about 3 × length along midline; submedian area smooth to weakly imbricate, with foveae or groove laterad median carina, delimited laterad and ventrad by complete plicae, dorsad by transverse band of foveae; callus with angulate process below spiracle, and alveolate-rugose, with alveolae sometimes obliterated below spiracle; nucha with transverse to arcuate rugae. Fore wing: elongate, WL / WW 2.3–2.4; hyaline, with yellow or brown venation; parastigma swollen with weak equilateral triangular process; postmarginal vein 0.7–0.8 × as long as marginal vein; stigmal vein 0.3–0.4 × as long as marginal vein; stigma with weak uncus.

Metasoma: petiole short and straplike, with weak transverse wrinkles; petiolar flange short with ventral margin of upper area with shallow emargination mesad; antecostal sulcus transverse, with weak vertical carinae laterad and smoothened mesad; Mt 2 with trapezoidal demarcation and shallow median groove, imbricate and wrinkled anteriad, and smooth posterad without lateral protruberances along midline, posterior margin straight and sparsely setose; Gt 3 smooth.

Male. As in female, except: Color: mesonotum sometimes nearly entirely black or with cupreous iridescence (Fig. 3 L cf. Fig. 3 K). Eye: in dorsal view often more bulbous (Fig. 3 H cf. Fig. 3 G). Ocellus: often larger (Fig. 3 H cf. Fig. 3 G). Ocellar ratios LOD: POL: OOL: LOL: often shorter. Frontal carina: distance from lateral ocellus usually shorter. Malar space: MSL / EH often shorter. Flagellum: slightly wider (Fig. 3 J cf. Fig. 3 I). Scape (Fig. 3 F): in anterior view weakly expanded distad, 1.3–1.4 × width above radicle; with distinct pits on anterior surface (Fig. 3 F cf. Fig. 3 D, E); pitted surface not swollen in lateral view. Aedeagus: without a pair of lateral spines.

Diagnosis.

The P. hyalinus species group is characterized by: brightly iridescent coloration (Fig. 2 A, H), distinct frontal carina extended from posterior margin of median ocellus (Fig. 2 B cf. Fig. 2 C) to near lower eye margin (Fig. 2 A), oblique costae obliterating malar sulcus (Fig. 2 D cf. Fig. 2 E), carinulate pronotum (Fig. 2 H cf. Fig. 2 I), distinct and uninterrupted notaulus (Fig. 2 H), axilla with axillar shelf (Fig. 2 F cf. Fig. 2 G), and elongate and finger-like axillula (Fig. 2 F cf. Fig. 2 G). The P. platigaster species group has a similar structure of the frontal carina, axilla, and axillula, but is distinguished by having a malar sulcus (Fig. 2 E cf. Fig. 2 D) and the general body color black with or without weak iridescent reflections (Fig. 2 I cf. Fig. 2 H).

Distribution.

The P. hyalinus species group occurs exclusively in the Western Hemisphere, from the southern Canada to Argentina.

Host association.

The previously published host records indicate that species are mostly hyperparasitoids, parasitizing dipteran ( Tachinidae and Sarcophagidae) and hymenopteran parasitoids (Ichneumonoidea) of Lepidoptera, Orthoptera, and rarely, Phasmatoidea and Coleoptera (e. g. Smith 1912; Smith 1958; Pitts et al. 2002; Janzen and Hallwachs 2009). Smith (1912) gave a detailed description of the biology of P. hyalinus Say as an indirect hyperparasitoid — the planidia actively searches and burrows into the host of the primary parasitoid (e. g. caterpillars), but can only feed and develop on the dipteran or hymenopteran parasitoids. There are relatively fewer cases of primary parasitoids in the P. hyalinus species group, and the best documented are the parasitoids of Neodiprion sawflies ( Hymenoptera: Diprionidae) (Tripp 1962).

Remarks.

This species group was hypothesized as a monophyletic group based on morphological characters (Darling 1996) and was well corroborated in our combined analysis of COI and ITS 2 (Fig. 1). The oblique costae obliterating the malar sulcus (Fig. 2 D) is the only shared and putatively derived character exclusive to this species group. Other character states (e. g. frontal carina) are widely distributed across Perilampidae in varying combinations, and a comprehensive phylogenetic analysis of this family is required to understand their evolution. Yoo (2023) recognized two clades in the P. hyalinus species group supported by COI + ITS 2 and morphology: the P. carolinensis species complex, which has a parascrobal area abruptly narrowed in lateral view and the lateral panel of pronotum without a flange (Fig. 1 Clade II), and the P. hyalinus species complex which has a parascrobal area usually gradually narrowed in lateral view and the lateral panel of pronotum with or without a flange (Fig. 1 Clade III). The P. hyalinus species complex is further divided into three major clades which are congruent in genetic and morphological characters, for example the density of pits on the male scape, the shape of the lateral panel of the pronotum, and color of the mesonotum in females (Yoo 2023). The species in the P. hyalinus clade 3 (IIIc, Fig. 1), including P. arcus, P. seneca, and P. ute, are distinguished by a usually densely pitted male scape (Figs 17 G, 17 H, 19 H, 19 I, 21 G, 21 H) and the lateral panel of pronotum with a triangular flange (Figs 16 D, 18 D, 20 D). The species in the P. hyalinus clade 1 (IIIa, Fig. 1), including P. sonora, can be recognized by the cupreous mesonotum in females (Fig. 22 B), in addition to the usually sparse pits on the male scape (Fig. 23 G, H) and the lateral panel of the pronotum that lacks a triangular flange (Fig. 22 D). The P. hyalinus clade 2 species (IIIb, Fig. 1), including P. crassus, P. neodiprioni, P. hyalinus, P. monocteni, P. pilosus, and P. sirsiris, also has a sparsely pitted male scape (Figs 5 G, H, 7 F, G, 9 G, H, 11 G, H, 13 G, H, 15 F, G) and the lateral panel of pronotum without a triangular flange (Figs 4 D, 6 D, 8 D, 10 D, 12 D, 14 D). But the P. hyalinus clade 2 species do not have the strong cupreous mesonotum in females (e. g. Fig. 4 B), except in P. pilosus (Fig. 15 A).