Psephenops panamaensis sp. nov. Arce-Pérez (Figs. 1–9) Description. Holotype Male: Body oval, depressed; integument black, elytra slightly reddish, completely covered with iridescent, reddish-yellow, long and short setae (Figs. 1, 6); coxae and trochanters dark brown; basal half of profemora dark brown, distal half black; tibia and tarsi black; venter black, vestiture short, fine and dense, gray-yellowish with yellow reflections. Total length 2 mm. Head: Short, transverse; clypeus subrectangular, declivous at an angle of less than 90 degrees from the plane of the frons, distal margin widely emarginate; fronto-clypeal surface with long, stout, black setae; vertex minutely punctate, with minute setae and a longitudinal furrow at middle. Antennae long (e.g. when fully extended backwards, reaching posterior margin of pronotum), moniliform-serrate, 11 -segmented, scape larger than other antennomeres, pedicel 0.50 length of scape and subglobose, third antennomere triangular and shorter than pedicel, antennomeres 4–6 serrate, antennomeres 7–10 small and moniliform, apical antennomere acuminate. Eyes lateral, rounded, very prominent, black, with a yellow post-ocular area. Labrum similar to clypeus but shorter. Maxillary palpi 4 -segmented, covered with short setae, basal palpomere smallest, apical palpomere largest, relative proportion of palpomeres: 0.3, 0.9, 0.6, 1.0; palpomeres 1–3 subconical, palpomere 4 oval, inflated from the base and gradually narrowing to tip (acuminate). Labial palpi very short, 3 -segmented, palpomeres 1–2 rounded and wide, palpomere 3 subconical and slightly shorter than preceding ones. PLATE I. Figures 1–6. Psephenops panamaensis sp. nov. 1. Male habitus, dorsal view. 2. Head and pronotum, dorsal view. 3. Detail of pronotum showing carina and anterior depression, dorsal view. 4. Detail of pronotal carina and anterior depression, dorsolateral view. 5. Detail of pronotal vestiture, dorsal view. 6. Detail of elytral vestiture, dorsal view. Thorax: Pronotum subtrapezoidal, almost as wide as elytral base; anterior margin arcuate, posterior margin bisinuate, 0.74 mm; lateral margins 0.32 mm, nearly straight along anterior half and expanded laterally on posterior half; posterolateral angles subacute. Pronotal disc with a well-developed, dorsomedial, longitudinal carina, on the distal half, preceded by a wide, transverse depression, and a wide, oval, deep depression to each side of the carina (Figs. 2-4); pronotal surface minutely punctate, covered with a minute, velvety, golden-yellow vestiture, and intermingled short and long yellowish-red setae; anterior and lateral margins with long, thick, black setae (Figs. 2–5). Scutellum short, wider basally than long, apex rounded. Elytra with short and long reddish-yellow setae (Fig. 6); sides parallel on basal 0.75, then gradually converging posteriorly; humeral width 0.94 mm. Prosternum short, with a long, lanceolate prosternal process which reaches anterior half of mesoventrite. Mesoventrite short, with a wide groove for reception of prosternal process. Metaventrite large and bulky. PLATE II. Figures 7–10. Male genitalia of Psephenops panamaensis. 7. Phallobase, parameres and midlobe (penis), dorsal view. 8. Same, ventral view. 9. Same, lateral view. Fig. 10. Male genitalia of Psephenops smithi, phallobase, parameres and midlobe (penis) dorsal view. Legs: Procoxae globose, mesocoxae conical, metacoxae transverse; femora robust; tibiae slender, metatibiae longer than femora, protibiae each with a distinct, apicolateral denticle. Tarsi 5 -segmented, tarsomeres 1 and 2 lobed ventrally, with a thick sponge-like vestiture; ventral lobe of tarsomere 1 extending distally over basal 0.25 of tarsomere 2; tarsomere 2 the longest, twice as long as tarsomere 1, extending distally and completely covering tarsomeres 3, 4, and basal 0.80 of tarsomere 5; proportional length of tarsomeres: 0.50, 1.00, 0.16, 0.16, 0.75; a pair of long, curved, slender apical claws, each with small basal tooth. Abdomen: Vestiture short, fine, dense, with yellow iridescence and intermingled dark reddish setae. Seven visible ventrites in relaxed specimens; ventrite VI usually hidden under ventrite V; ventrite II largest. Posterior margin of ventrite I deeply concave at middle, sinuate at sides; posterior margin of ventrite II as in ventrite I but with a shallow concavity in the middle; posterior margin of ventrites III and IV straight; ventrite V with a wide, shallow concavity; ventrite VI very short, posterior margin widely concave. Pygidial plate oval, long, narrow and densely covered with a long, stiff, dark reddish setae. Genitalia: Short, wide, subrectagular, trilobate (Figs. 7–9); total length 0.30; total width 0.12; parameres 0.09, penis 0.20; phallobase: length 0.10, width 0.13. Measurements (in mm) variation in paratypes [N= 19]: Total length 1.70–2.40, mean= 1.95. Pronotum: posterior margin 0.72–0.80, mean= 0.75, lateral margin 0.32–0.38, mean= 0.33; elytra: humeral width 0.84–0.94, mean= 0.89. Type material. Holotype male labeled: PANAMA, Darién, Parque Nacional Darién, Estación Rancho Frío, Río Perresénico, 117 masl, (08°01.714’ N, 77 ° 72.417 ’ W), 20 -XI- 2014, R. Novelo col. (IEXA). Paratypes, 19 males, same data as holotype; 8 (IEXA), 8 (Museo de Invertebrados, Universidad de Panamá), 3 (NHMW). Ecology. The specimens of P. panamaensis sp. nov. were collected flying over turbulent rapids in the center of the stream, on a sunny day in the tropical rain forest, together with some specimens of Hexanchorus crinitus Spangler & Santiago, and Disersus longipennis Sharp 1882 (Elmidae: Larainae). Etymology. Because this is the first record of the subfamily for Panama, the species name is used as a noun in apposition. Remarks. Psephenops panamaensis sp. nov. can be separated from other known Psephenops species by the combination of the following features [other species in brackets]: body length shorter than 2.4 mm, according to our measurements [all others longer than 2.4 mm]; antennae long, reaching posterior margin of pronotum [short, hardly surpassing basal half of pronotum, P. mexicanus, P. prestone, P. smithi, P. maculicollis, P. spiniparameri, P. argentinensis]; antennae moniliform-serrate [moniliform or filiform in all others except P. grouvellei]; pronotum without tubercles [with 3 small tubercles grouvellei]; elytra with striae [lacking striae, P. mexicanus, P. lupita, P. prestone, P. spiniparameri, P. shepardi; not described for P. smithi and P. grouvellei]; protibiae with denticles [without denticles, P. prestonae; not described for P. grouvellei, P. smithi, P. haitianus, P. argentinensis]; ventral lobes of tarsomere 2 enlarged (e.g. extending distally completely covering tarsomeres 3 and 4, and basal 0.80 of tarsomere 5) [ventral lobes of tarsomere 2 shorter, not reaching more than 0.5 basal of tarsomere 5 or less, P. grouvellei, P. lupita, P. shepardi, P. smithi; not described for P. haitianus and P. argentinensis]; parameres truncate [not truncate in all others except P. smithi]. Similar male genitalia characteristics indicate that P. panamaensis may be closely related to P. smithi (cf. Figs. 7–10), although both species are clearly differentiable by the length of midlobe (penis) in relation to the parameres’ length, the type of antenna and the length of antennae and tarsomeres. However, for a better interpretation of the relationships among the species of Psephenops, a revision of the entire genus would be necessary. The comparisons mentioned here are based mainly on original descriptions and illustrations; the features of P. s m i t hi were taken from Deléve (1967) and Bameul (2001).