Chaco costai, 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 : 80-82

Chaco costai sp. n. Figs 2 A–F, 4 A–E

Types.

Male holotype (FCE-MY 1007) female paratype (FCE-MY 1006) and from Rocha, Perla de Rocha, 34°25.63'S, 53°52.27'W, 26-28.xii.2011, coll. A. Laborda, C. Castro, L. Montes de Oca.

Etymology.

The specific epithet is a patronym in honor of Fernando G. Costa, a recognized Uruguayan arachnologist who greatly contributed to the knowledge of spiders and has inspired many colleagues and students.

Diagnosis.

Males of Chaco costai (Fig. 2A) differ from the other species of the genus, except Chaco obscura , by the presence of numerous spines (7-10) on tibial apophysis (Fig. 4D); they can be distinguished from Chaco obscura by having a shorter embolous (Figs 4 A–C). Female Chaco costai specimens (Fig. 2C) differ from most species of Chaco by having spermathecae with a sinuous neck (Fig. 4E). The species is distinguished from the geographically proximate species Chaco castanea by having a longer spermathecal neck and from Chaco obscura by the sinuous neck. Chaco costai differ from all other species of the genus (except Chaco patagonica and Chaco tecka ) by having a flap door that covers the burrow (Fig. 2E).

Description.

Male (holotype). Total length 14.9; carapace 7.7 long, 6.2 wide; eight eyes grouped on a tubercle, AME 0.28; PME 0.23; ALE 0.38; PLE 0.36; OQ 0.79 long, 1.04 wide; clypeus 0.22; fovea transverse, slightly procurve 1.5; sternum oval, 3.1 long, 2.8 wide. Posterior sigillae sub-circular, sub-marginal. Labium sub-rectangular, 1.2 long, 3.5 wide; 4 labial cuspules; 42/38 maxillary cuspules (Fig. 2B); chelicerae with 2 row of teeth, 6 promarginal, 5 retromarginal denticles; rastellum with 16 short, thick conical setae on promargin. ITC absent. Claw tufts absent. Leg, palpal measurements in Table 6; chaetotaxy in Table 7. Tarsus I-III scopula entire, IV divided; metatarsi I 4:5D, II 3:4 D, III 1:5 D, IV absent. Anterior tibiae without scopula. STC with numerous teeth in two lateral rows. Tibial apophysis with 7-10 prolateral apical spines (Fig. 4D). Palpal tibia with 2 dorsal long thin setae. Palpal organ spermophor very sinuous (Figs 4 A–C). Four spinnerets, PMS short monoarticulated, PLS triarticulated apical article short, domed. Spigots without pumpkin-like socket. Cephalothorax, legs dorsally light brown, and ventrally dark brown; abdomen lighter with dark brown pattern.

Female (paratype). Total length 19.9; carapace 7.1 long, 5.7 wide; caput raised; eight eyes grouped on a tubercle, AME 0.2; PME 0.17; ALE 0.36; PLE 0.35; OQ 0.63 long, 1.16 wide; clypeus 0.27; fovea slightly procurved 1.10; sternum oval, 3.4 long, 2.9 wide. Posterior sigillae sub-circular, sub-marginal. Labium sub-rectangular, 0.47 long, 0.97 wide; 3 labial cuspules; 43/36 maxillary cuspules (Fig. 2D). Chelicerae with 8 promarginal teeth; 9 retromarginal denticles; rastellum with 18 short, thick conical setae on promargin. Leg, palpal measurements in Table 8; chaetotaxy in Table 9. Tarsus I-II scopula entire, III- IV divided by a wide band of longer conical setae, metatarsus I complete, II 2:3, 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 median line. Two spermathecal receptacles, single sinuous long neck; sub-espheric fundus (Fig. 4E). Four spinnerets, PMS short monoarticulated, PLS triarticulated apical article short, domed. Spigots without pumpkin-like socket. Cephalothorax, legs brown, abdomen very light brown with darker dots.

Distribution.

Only known from the type locality.