Soesilarishius chaplini sp. nov.

Figs 1–3, 8–12

Type material: Holotype: male from Parque Nacional da Serra do Pardo, São Félix do Xingu, Pará, Brazil, 5.767ºS, 52.617ºW, 26.IV.2012, G.R.S. Ruiz et al. (MPEG 20276). Paratype: 1 female, same data as holotype, MPEG 20277.

Etymology. The specific epithet is in honor of Sir Charles Spencer Chaplin for the resemblance between his characteristic moustache and the modified scales on the male clypeus (Fig. 3).

Diagnosis. Males of this species can be distinguished from those of all the remaining known species by having the typical black scales on the light clypeus (Fig. 3). Females can be distinguished from those of the remaining species by having a “young-duck-face” on the epigynal plate, formed by the copulatory openings and the advanced median pocket (Fig. 11).

Description. Male holotype: Total length: 2.47. Carapace yellow, 1.52 long, 1.04 wide, 0.68 high, with cephalic region dark brown and oblique lines of white scale behind the posterior eyes; a transverse dark brown band behind the fovea and another along the posterior border of the carapace (Fig. 1). Ocular quadrangle 0.78 long. Anterior eye row 1.09 wide and posterior 0.99 wide. Clypeus with modified dark scales (Fig. 3). Chelicera yellow, small. Endite, labium and sternum light brown. Palp dark brown, with a strongly, ventrally curved RTA (retrolateral tibial apophysis), elongate cymbium, kidney-shaped tegulum and short, dorsally curved embolus at the distal end of tegulum (Figs 8–10). Legs 1=342; I-II dark brown with tarsi and distal half of metatarsi yellow; III-IV yellow with patellae and distal half of femora dark brown. Length of femur: I 0.85, II 0.71, III 0.85, IV 0.83; patella + tibia: I 1.09, II 0.78, III 0.95, IV 0.85; metatarsus + tarsus: I 0.76, II 0.68, III 0.85, IV 0.95. Spination similar to that described for S. lunatus (Ruiz, 2011, fig. 60). Abdomen dark brown, dorsally with two light chevrons that fuse each with a pair of lateral, clear spots (Fig. 1). Spinnerets light colored.

Female (paratype): Total length: 2.75. Carapace dark brown, 1.54 long, 1.09 wide, 0.71 high (Fig. 2). Ocular quadrangle 0.83 long. Anterior eye row 1.09 wide and posterior 0.99 wide. Chelicera, endite, palp, labium and sternum light brown. Legs 4312; I-II dark brown, III-IV with dark brown femora, other articles yellow. Length of femur: I 0.80, II 0.66, III 0.87, IV 0.80; patella + tibia: I 0.99, II 0.80, III 0.95, IV 0.90; metatarsus + tarsus: I 0.71, II 0.66, III 0.85, IV 0.99. Spination as in male. Abdomen dorsally dark brown, variegated (Fig. 2); ventrally creamcolored. External epigynal structures resemble a young duck face, the eyes being the semicircular copulatory openings wide apart and the beak being the median pocket, apart from the posterior border (Fig. 11). Internally, copulatory ducts flow straight to the center, with glands on their anterior walls, curve backwards, reaching posterior, round spermathecae; these have nutritive glands near the fertilization ducts, which arise on their anterior surface (Figs 11–12). Spinnerets yellow.

Distribution. Known only from the State of Pará, Brazil.

Biological note. The specimens mentioned above were actively collected from the humid forest ground. They are abundant at the type locality, but easily found only by trained eyes. Small, dark, with the general color and scale pattern that camouflages them among the dark fallen leaves covered with shiny drops of water, these spiders are only spotted on the rarely illuminated ground of rainforests after their short jumps. Despite abundant, these animals were not commonly collected with pitfall traps.