Perilampus arcus Yoo & Darling 2024, sp. nov.

Perilampus arcus Yoo & Darling sp. nov. Figs 20, 21 Type locality. USA, West Virginia, Hardy County, 3 mi NE Mathias. Type material. Holotype. “ WEST VIRGINIA: Hardy Co. 3 mi NE Mathias 38.9098, -78.8881, 14–31. VII. 2007, Malaise David R. Smith ”. The holotype is point-mounted (Female ROME 189051, USNM). BOLD: AEE 7608 / ITS 2. ROM Online Collection. Paratypes. Canada: 1 male. Ontario: 1 male. Norfolk Co., Normandale Fish Hatchery, 42°43'08"N, 80°20'23"W: (1 male: ROME 198214 - CNC; BOLD: AEE 7608; ITS 2). USA: 5 females. Kentucky: 1 female. Jessamine Co., S. of Nicholasville, 37°47'04"N, 84°34'11"W: (1 female: ROME 158551 - ROME; BOLD: AEE 7608). West Virginia: 4 females. Hardy Co., 3 mi NE Mathias, 38.9098, -78.8881: (4 females: ROME 185944 - USNM; BOLD: AEE 7608; ITS 2; ROME 189050 - USNM; ITS 2; ROME 189052 - USNM; BOLD: AEE 7608; ITS 2; ROME 189131 - USNM; ITS 2). Material examined. Canada: 2 females, 1 male. USA: 6 females, 1 male. (Suppl. materials). Etymology. The specific epithet is the Latin noun arcus (arch), in reference to the steeply curved parascutal carina. Description. Female (Fig. 20). Length: 2.7–4.0 mm. Color: head iridescent greenish blue or violet; mesosoma and metasoma iridescent greenish blue or violet; clypeus ventral margin black (Fig. 20 I); antenna with scape and pedicel weakly iridescent greenish blue or violet, flagellum brown or black, lighter ventrad and distad. Head (Fig. 20 G – J): in dorsal view transverse, width slightly greater than twice length, HW / HL 2.1–2.2. Frontal carina: in anterior view straight to weakly sinuate below midlevel of eye; in dorsal view gradually narrowed V shape around median ocellus, FC / MOD 1.5–1.6; distance from lateral ocellus short, FCLO / LOD 0.5–0.6. Scrobal cavity (Fig. 20 H): in anterior view wide, SW / HW about 0.5. Ocelli (Fig. 20 G): a line between anterior margin of lateral ocelli reaching anterior margin of median ocellus. POL / OOL 1.6–1.9. Ocellar ratios LOD: POL: OOL: LOL 1, 2.5–2.9, 1.6–1.8, 0.8–1.0. Vertex: with strong to weak transverse striations, without large piliferous punctures. Parascrobal area: in lateral view gradually narrowed towards lower eye margin; width narrow, PSW / EL 0.2–0.3; sculpture strongly to weakly striate, without large piliferous punctures. Gena (Fig. 20 J): mostly striate along outer eye margin with narrow and short smooth area, striate behind. Malar space: MSL / EH about 0.2. Lower face (Fig. 20 H, I): with setae sparse or dense and narrowly distributed laterad torulus, and usually sparse below. Clypeus (Fig. 20 I): CW / CH 1.3–1.4; ventral margin concave; setae evenly distributed, or with small bare area without setae medially. Mesosoma (Fig. 20 B – F, K, L): Lateral panel of pronotum: slightly narrower than prepectus, LPP / PPT 0.7–0.8; usually with small triangular flange below level of mesothoracic spracle in posterior oblique view (Fig. 20 D, arrow). Mesofemoral depression: usually smooth, rarely weakly rugulose or weakly imbricate ventrad (Fig. 20 L). Mesoscutum: punctures angulate, with narrow and weakly coriarious interspaces (Fig. 20 B); lateral lobe smooth or weakly punctate along notaulus (Fig. 20 C); parascutal carina steeply curved, often weakly flanged (Fig. 20 E, arrow). Mesoscutellum: apex with inner margins gradually (Fig. 20 K) or abruptly diverging; punctures angulate, with narrow and weakly coriarious interspaces. Axilla (Fig. 20 F): in lateral view imbricate dorsad and carinate ventrad. Axillula: smooth dorsad. Fore wing: stigma small, 2.0–2.5 × as wide as postmarginal vein. Male (Fig. 21). Length: usually smaller, 3.1–3.5 mm. As in female, except: Color: mesonotum sometimes with weak cupreous iridescence. Frontal carina: distance from lateral ocellus shorter, FCLO / LOD 0.3–0.4. Scape (Fig. 21 G, H): pits dense, covering about 0.4 × scape length. Diagnosis. The steeply curved parascutal carina often with a flange distinguishes P. arcus from the majority of the species of the P. hyalinus species complex (Figs 20 E, 21 B cf. Figs 16 E, 17 B). Perilampus sirsiris also has a similar parascutal carina (Figs 6 F, 7 B), but it is always steeply curved in P. arcus and usually angulate in P. sirsiris (Fig. 20 E cf. Fig. 6 F). Perilampus arcus also differs from P. sirsiris by having the lateral panel of pronotum with a small triangular flange in posterior oblique view (Fig. 20 D, arrow cf. Fig. 6 D, E) and a male scape with a densely pitted surface (Fig. 21 G, H cf. Fig. 7 F, G). In addition to the shape of the parascutal carina, sparser setae on the lower face usually distinguish P. arcus from P. seneca (Figs 20 I, 21 C cf. Figs 16 I, 17 C), which also has a small triangular flange on the pronotum (Figs 16 D, 17 B) and a densely pitted male scape (Fig. 17 G, H). Distribution (Fig. 25 E). Southeastern Canada and eastern USA, possibly southcentral USA: Canada (Ontario), USA (Arkansas, Kentucky, Ohio, West Virginia, Wisconsin). Host association. Unknown. Remarks. This species is supported by both genes (Fig. 1, Suppl. material 5), and there are five BINed specimens on BOLD (AEE 7608) from eastern Canada and USA. A single female was collected in Arkansas, indicating that the range of P. arcus may include the southern USA.