Figures 2A‒C, 3A, 3B, Appendix 1

Material examined. Holotype. “ Yemen: Al Hudaydah, Zabid, 14°11'0"N, 43°18'0"E, Oct 2001, A van Harten; I Al Futayni, Light trap ”, “Digital Image Voucher 2019, Royal Ontario Museum”. The holotype is point-mounted (Female: ROME159196, ROME).

Paratype. Yemen: Abyan, Al Kowd, 13°5'0"N, 45°22'0"E: Jul-Sep 2001, A van Harten; S Al Haruri, Malaise trap (1 female: ROME159194 - EAD).

Etymology. The specific epithet ardens, Latin for fiery, is a reference to the red and yellow iridescent coloration on margin of the tubercle on the mesoscutum.

Description. Female. Length: approximately 2‒2.5 mm (HT 2.5 mm). Color: iridescent blue-green, metasoma brown with strong blue-green reflections; raised smooth scale on mesoscutum with bright red and yellow reflections; dorsellum iridescent blue-green. Legs: coxae brown with green reflections, pro- and mesofemora and tibiae brown to yellow, lighter distad and on inner surfaces, hind femora brown with weak blue-green reflections, tarsi brown. Antennae: scape brown with iridescence, pedicel brown, flagellum yellow.

Head (Figs 2B, 2C, 3A): in frontal view transverse, wider than high, HW/HH approximately 1.3, sparsely setose to smooth; in dorsal view weakly transverse, width slightly greater than twice length, HW/HL 2.1‒2.2; slightly wider than pronotum, HW/PW approximately 1.1‒1.2. Frontal carina: absent. Scrobal cavity (Fig. 2B): shallow; with weakly swollen ridge with wrinkles originating from between median and lateral ocelli extended towards eye margin. Ocelli: large; forming a wide triangle, POL about twice distance between posterior and anterior ocelli; POL at least twice OOL. Vertex: rounded behind; ocellar margins weakly foveate, interocellar region with costulae recurved towards the anterior ocellus; occiput with median furrow extended along midline of vertex (Fig. 2B, arrow), with costulae. Outer orbits: smooth, strong costulae behind. Inner orbits: in lateral view, nearly parallel to inner eye margin; weakly foveate. Malar space: short, about 0.2× eye height, MS/EH approximately 0.2; malar sulcus distinct; with very shallow piliferous punctures. Clypeus (Fig. 2C): strongly transverse, much wider than high, CW/ CH 2.1‒2.2, trapezoidal, lateral sulci weak and straight, strongly divergent; epistomal sulcus straight or weakly concave, deeper and more distinct than lateral sulci, only slightly extended ventrad, lower margin weakly convex. Supraclypeal area: subquadrate. Antenna: scape length approximately 0.6× EH; anellus subquadrate, length approximately 0.3× PL; F1 subquadrate, shorter or subequal in length to pedicel, F1L/PL approximately 0.6‒0.9, F2 subquadrate, F3‒F7 transverse; clava 4-segmented, with distinct terminal button.

Mesosoma (Figs 2A, 3A, 3B): length about 1.1× maximum width. Pronotum in dorsal view: short, about 0.25× length of mesoscutum, PN/MSC 0.2‒0.3; slightly shorter along midline, 0.7‒0.8× length laterad; anterior margin rounded; with flange on pronotal panel at the level of mesothoracic spiracle. Lateral panel of pronotum (Fig. 3B): narrower than prepectus, LPP/PPT approximately 0.6; flat, with 2 rows of punctures with narrow interspaces, vantrad with narrow coriarious patch; anterior margin rounded; posterior margin ventrad nearly flat, with row of alveolae. Prepectus: broad; differentiated from pronotum, with distinct suture; ventral strap short (Fig. 3B, arrow), without row of alveolae; central area smooth, with foveae along dorsal and posterior margins. Femoral depression: weakly rugose, with foveae. Midlobe of mesoscutum (Fig. 3A): with raised scale-like tubercle (Fig. 3A, arrow); punctures angulate, with narrow interspaces. Lateral lobe of mesoscutum: weakly rugulose dorsad; rugulose-punctate laterad. Scutellum (Fig. 3A): about as long as mesoscutum, SC/MSC approximately 1.1; posterior margin smoothly rounded; with angulate punctures and narrow interspaces. Axilla: punctate dorsad, imbricate below. Axillula: wide triangular lobe, as long as width at base, smooth. Propodeum: length along midline about 0.3× width of propodeum; submedian area shagreened to smooth, with weak groove along median carina; alveolate-rugose laterad; without distinct lateral plicae, delimited ventrad by plicae, dorsad by transverse band of foveae; propodeal spiracle margin reticulate ventrad; nucha rugulose. Fore wing (Fig. 2A): hyaline, with yellow venations; postmarginal vein long, 0.8‒0.9× length of marginal vein, approximately twice length of stigmal vein; stigmal vein rounded without uncus.

Metasoma (Fig. 3A): petiole short and straplike, smooth, without raised scale; Gt2 smooth, posterior margin concave; Gt3 smooth.

Male: Unknown.

Diagnosis. Perilampus ardens can be distinguished from P. awbalus and P. seyrigi, by the following: transverse clypeus (Fig. 2C), green-blue body coloration (Figs 2A, 3A), vertex rounded behind (Fig. 2B), occiput with furrow extended along midline of vertex (Fig. 2B, arrow), higher scale-like tubercle on the midlobe of mesoscutum (Fig. 3A, arrow), narrower pronotum (Fig. 3B), and smooth Gt3 (Fig. 3A). Perilampus ardens is morphologically similar to P. auratus but can be distinguished by the convex clypeal margin (Fig. 2C), red and yellow iridescent margin of the scale on the mesoscutum (Fig. 3A) and the wrinkled edge of scrobal cavity (Fig. 2B). See also Appendix 1, P. auratus and P. seyrigi.