Clinopsocus nigrescens n. sp.

Diagnosis. With the characters of the genus, as noted above. Differing from C. phragmitellus (Smithers, 1972) and C. smithersi (New, 1972) in: 1) presence of a placoid sensillum on antennal flagellar f7 – f9; 2) antennal flagellum terminating in a small knob (Fig. 3); 3) clypeal shelf of moderate width (Fig. 2), not strong; 4) lacinial tips of the two sides unequal in development (Figs 5, 6); 5) v3 (external valvula) triangular with outer edge straight, not incurved (Fig. 10a); 6) paraproctal sensorium indicated only by a bare circular area lacking sensilla but bearing a single large seta (Fig. 12; three large setae in a similar position in C. phragmitellus, cf. Smithers 1972: 19); 6) pigmented area of subgenital plate extended anteriorly as tapering, laterally-directed arms (Fig. 9).

Color (in alcohol 3 months). Head dark brown, eyes dusky gray. Antennae and legs black except femora brown, tarsi gray. Thoracic tergal lobes dark brown, with bordering areas medium grayish-brown. Abdomen with a dark brown tergal sclerite anteriorly; rest of preclunial abdomen grayish-brown with white spots (fat bodies) showing through cuticle. Subgenital plate, ovipositor valvulae, clunium, and telson lobes dark brown.

Structural characters. Habitus (Fig. 1). Median and frontal ecdysial lines distinct on cleared head. Vertex with vague reticulate sculpture becoming more pronounced medially on frons and generally on postclypeus. Clypeal shelf (as noted on cleared head) occupying slightly less than one-third dorso-ventral length of postclypeus (Fig. 2). Compound eyes small but multi-faceted, with scattered short setae (Fig. 2, setae not shown). Antennae about 1.5x width of head in length; with scattered setae of varied lengths throughout, some on f2 – f4 up to 4.5x as long as width of their flagellomere; with placoid sensilla: one at or near distal end of f1, one distally on f4, f6, f7, f8, f9, and f10; those on f8 – f10 with filament somewhat longer than the others. Labrum with short stylets; with 4 outer and 11 inner distal sensilla; inner distals in two series, 6 basal and 5 peripheral; the 6 basals each with a long filament; of the 5 peripherals, the outer two and the single median lack filaments while each of the other two has a relatively heavy filament (Fig. 4). Wings present as thin lateral extensions of the meso- and metathoracic notal lobes (Fig. 8), each bearing a few small setae. Legs slender; all tibiae with several longitudinal rows of setae; hind tibiae with an outer row of gland hairs. Pretarsal claw (Fig. 7) with preapical denticle of moderate size, pulvillus setiform. Subgenital plate (Fig. 9) with distal median lobe (‘egg guide’) short, bearing four stout setae distally; pigmented area extended laterally as slender arms. Ovipositor valvulae: v1 with slight membranous pouch at base of slender terminal process (Fig. 10b); v2 with more pronounced pouch at base of terminal process (Fig. 10a); v3 with long setae on distal margins and scattered on outer face. Spermathecal remnant (Fig. 11) opening on a thin plate. Epiproct (Fig. 12) with scattered setae, including several long setae on hind margin. Paraprocts with setae mostly on margin; sensorium indicated only by a pale, circular area near base.

Body ciliation (see also “structural characters”). Head: setae of parietal and frontal regions and postclypeus slender and acuminate-tipped; those near hind margin of vertex blunt-tipped. Setae of thoracic notal lobes: short, acuminate-tipped setae in two rows anteriorly on mesonotum; setae 2– 3x longer, blunt-tipped, in three rows posteriorly on mesonotum and scattered across metanotum. Setae of basal abdominal tergal plate about same size as larger setae of thoracic notal lobes and all blunt-tipped; remainder of preclunium with scattered setae somewhat shorter and slenderer than those of basal tergal plate, all blunt-tipped; sculpture lines of cuticle bearing scattered microtriches. Setae of abdominal sterna, all external genitalic structures, and telson lobes acuminate-tipped.

Measurements (µm). BL = 2009; F = 402; T = 558; t1 = 100; t2 = 87; f1 = 129; f2 = 83; f3 = 78; f4 = 57; total antenna = approx. 830; IO = 424; d = 74; IO/d = 5.72; D = 131; IO/D = 3.25.

Material examined. Holotype and 42 paratypes: USA: California: Alameda County: San Leandro, 13 January 2017, on old wooden boards stored in a garage, coll. J. Gross.

Etymology. The specific name ‘nigrescens’ (becoming dark) refers to the general coloration of this species.