Chaco castanea, Oca, Laura Montes de & Perez-Miles, Fernando, 2013

Oca, Laura Montes de & Perez-Miles, Fernando, 2013, Two new species of Chaco Tullgren from the Atlantic coast of Uruguay (Araneae, Mygalomorphae, Nemesiidae), ZooKeys 337, pp. 73-87 : 77-79

Chaco castanea sp. n. Figs 1 A–D, 3 A–E

Types.

Male holotype (deposited in FCE-MY 0767) from, Rocha, Perla de Rocha, 34°25.0'S, 53°51.0'W, i.2001, coll. G. Calixto Female paratype (deposited in FCE-MY 0770) from Rocha, Cabo Polonio, 34°24.0'S, 53°47.0'W, 24. i– 18.iii.2003, coll. F. Achaval. Additional material examined. Male from Rocha, Cabo Polonio, 19.xii.2003-18.iii.2004, coll. F. Achaval. 1m (deposited in FCE-MY 0769), Female from Rocha, Perla de Rocha, 34°25.0'S, 53°51.0'W, i.2001, coll. G. Calixto, 1f (FCE-MY 0766), female from Rocha, Cabo Polonio, 34°24.0'S, 53°47.0'W, 18. i– 18.iii.2005, coll. F. Achaval, 1f (deposited in FCE-MY 0797).

Etymology.

The specific epithet is a noun taken in apposition (chestnut) and is in reference to the brownish coloration of this species.

Diagnosis. Males (Fig. 1A) uniquely possess a tibial apophysis with 4 spines (Fig. 3D). Chaco castanea males differ from Chaco tigre and Chaco socos males by having a palpal organ with a sinuous spermophor and parallel longitudinal ridges (Figs 3 A–C), and by having a PME and AME that are subequal in diameter. Females of Chaco castanea (Fig. 1C) differ from the other known Chaco species by the presence of a large reniform spermathecal receptacle in combination with a short sinuous duct (Fig. 3E).

Description.

Male (holotype). Total length 7.75; carapace 4.13 long, 3.27 wide; eight eyes grouped on a tubercle, AME 0.17; PME 0.13; ALE 0.16; PLE 0.16; OQ 0.86 long, 0.44 wide; clypeus 0.06; fovea 0.63; sternum oval, 1.93 long, 1.56 wide. Posterior sigillae sub-circular, sub-marginal. Labium sub-rectangular, 0.2 long, 0.56 wide; labial cuspules absent; 18/20 maxillary cuspules (Fig. 1B); chelicerae with 7 promarginal teeth of similar size; rastellum with 26 short, thick conical setae on promargin narrowing through retromargin. Leg, palpal measurements in Table 2; chaetotaxy in Table 3. Tarsus I-IV scopula entire; metatarsi I-II distal third, III-IV absent. Anterior tibiae without scopula. STC with numerous teeth in two lateral rows. ITC I-IV absent. Claw tufts absent. Tibial apophysis with 4 prolateral apical spines (Fig. 3D). Palpal organ spermophor strongly sinuous (Figs 3 A–C). Four spinnerets, PMS short monoarticulated, PLS triarticulated apical article short, domed. Spigots without pumpkin-like socket. Body, legs light brown, abdomen with dark brown spots.

Female (paratype). Total length 18.2; carapace 7.2 long, 5.6 wide; caput raised; eight eyes grouped on a tubercle, AME 0.24; PME 0.25; ALE 0.36; PLE 0.31; OQ 0.75 long, 1.6 wide; clypeus 0.14; fovea 0.9; sternum oval, 2.3 long, 2.2 wide. Pos terior sigillae sub-circular, sub-marginal. Labium sub-rectangular, 0.7 long, 1.3 wide; 1 labial cuspule; maxillary cuspules 48/62 (Fig. 1D). Chelicerae with 6 promarginal teeth; first tooth smaller than second, decreasing thereafter; 10 retromarginal denticles; rastellum with 45 short, thick conical setae on promargin. Leg, palpal measure ments in Table 4; chaetotaxy in Table 5. Tarsus I-IV scopula entire, metatarsus I-II entire, III–IV absent. Anterior tibiae without scopula. STC with numerous teeth in two lateral rows. ITC I-IV absent. Claw tufts absent. Palpal claw with 4 teeth in prolateral median line. Two spermathecal receptacles, single sinuous neck; reniform fundus (Fig. 3E). Four spinnerets, PMS short monoarticulated, PLS triarticulated apical article short, domed. Spigots without pumpkin-like socket. Coloration as in male.

Distribution.

Uruguay, Rocha, Perla de Rocha and Cabo Polonio.