Hemirrhagus billsteelei Mendoza & Francke 2018, sp. nov.

Hemirrhagus billsteelei sp. nov.

(Figs 6 ̄9)

Type material: holotype ♂ CNAN T0925, paratype ♀ CNAN T0926, paratype ♀ CNAN-T0927, MEXICO: Oaxaca, Mpio. Huautla de Jiménez, Cueva de La Grieta, 10-IV-2014, Coll. J. Mendoza, S. Davlantes, A. Guzman.

Diagnosis. Hemirrhagus billsteelei sp. nov. can be distinguished from all other Hemirrhagus species, except H. perezmilesi, in lacking tibial apophyses. From H. perezmilesi in the shape of male palpal bulb, the spermatheca, the stridulating setae composed by spinose and claviform setae, instead of claviform parallel and spinose setae.

Hemirrhagus billsteelei sp. nov. is identified by possessing the following character combination. Male palpal bulb with slender embolus similar in length to tegulum, subapical keel ends at embolus retrolateral face; ventral groove deep. Embolus curved retrolaterally on distal half (Fig 7A ̄D). Tibia I lacking apophyses (Fig 6I). Ocular tubercle and eyes normally developed, periocular pigmentation complete (6E, 8C). With stridulatory setae conformed by spinose setae on retrolateral face of palp trochanter and claviform setae on prolateral face of trochanter I (Fig 6G, H; 8E, F). Urticating setae arranged in two lateral, oval patches, black in color (Fig 6C). Spermatheca paired, slightly fused at the base, receptacles finger-shaped (Fig 8G).

Etymology: The specific name is a patronym in honor of Bill Steele, for his contribution to the knowledge of Mexican Caves and his help in the collection of cave tarantulas and other arachnids in the Huautla Cave System.

Description: Holotype male CNAN T0925 body length 21.17, carapace 10.10 long, 9.29 wide. Caput not elevated; fovea recurved, width 1.33 (Fig 6A).

Eyes: anterior eye row procurved, posterior eye row recurved. Periocular pigmentation complete, all eyes normally developed. Eye sizes and interocular distances: AME 0.35; ALE 0.40; PME 0.15; PLE 0.30; AME-AME 0.075; AME-ALE 0.125; PME-PME 0.675; PME-PLE 0.075; ALE-PLE 0.10. Ocular tubercle slightly reduced, ocular quadrangle width 1.5, length 1.125; clypeus 0.05 (Fig 6E). Labium length 1.37, width 1.80; with 48 cuspules. Maxilla inner corner with ~112 (left) and ~126 (right) cuspules (Fig 6F). Cheliceral promargin with 13 (left) and 13 (right) teeth (proximal to distal: first small, second-eighth medium, ninth-thirteenth large). Sternum length 4.25. Sigillae oval, first, second and third pairs hardly visible; posterior sigilla half its length from the margin (Fig 6B).

Leg formula: IV, I, III, II. Length of legs and palpal segments (femur, patella, tibia, metatarsus, tarsus, total): I: 10.32, 5.45, 9.55, 10.09, 7.56, 42.97. II: 9.70, 5.13, 8.49, 9.61, 7.56, 40.49. III: 9.60, 4.24, 8.53, 11.14, 7.15, 40.66. IV: 11.77, 4.48, 10.53, 10.56, 8.53, 45.87. Palp: 7.43, 3.72, 6.88, -, 3.04. Spinnerets: PMS, 1.0 long, 0.33 apart; PLS, 1.37 basal, 1.50 middle, 2.67 distal; midwidths: 0.67 basal, 0.60 middle, 0.50 distal (Fig 6D).

Scopulae: Tarsi I-IV entirely scopulated, III divided by narrow band of setae and IV divided by strong band of setae. Metatarsi I-II densely scopulated; III 65 % scopulated distally, IV 50 % scopulated distally.

Tibia I lacking apophyses (Fig 6I). Metatarsus I straight (Fig 6J).

Stridulatory setae: On palpal trochanter retrolateral face proximally, with ca. 10 spinose setae of different sizes, disorganized. Trochanter I with claviform setae on prolateral face (Fig 6G ̄H). With plumose setae on palp coxa retrolateral face, trochanter retrolateral face, femur prolateral and retrolateral faces; leg I coxa prolateral and retrolateral faces, femur prolateral face; leg II trocanter prolateral face, femur prolateral face.

Chaetotaxy (left side): femora I 4 p, 3r; II 4 p, 3r; III 3 p, 5r; IV 4 p, 3r; palp 2p, 1r; patellae none; tibiae I 4 p, 10v, 1r; II 2 p, 9v, 1r; III 1 d, 4p, 6v, 4r; IV 1 d, 7p, 10v, 7r; palp 1p, 8v, 1r; metatarsi I 1 p, 3v; II 1 p, 1v; III 3 p, 7v, 6r; IV 9 p, 8v, 10r.

Palp. Embolus slender, one and a half times the length of tegulum, subapical keel ends at embolus retrolateral face; ventral groove deep. Embolus strongly curved retrolaterally in distal half. The apex of the embolus slightly curved ventrally (Fig 7A ̄D).

Urticating setae: Type VI arranged in two lateral, oval patches, black in color, with well-defined margins (Fig 6C).

Color pattern: in ethanol specimens color are brown. Live specimens are black (Fig 9C).

Paratype female CNAN-T0926 body length 21.96, carapace 9.54 long, 8.77 wide. Caput not elevated; fovea recurved, 1.27 wide (Fig 8A).

Eyes: anterior eye row straight, posterior eye row recurved. Periocular pigmentation complete, all eyes normally developed. Eye sizes and interocular distances: AME 0.33; ALE 0.43; PME 0.20; PLE 0.37; AME-AME 0.17; AME-ALE 0.17; PME-PME 0.63; PME-PLE 0.067; ALE-PLE 0.13. Ocular tubercle reduced, ocular quadrangle width 1.73, length 1.00; clypeus 0.17 (Fig 8C). Labium length 1.77, width 2.0; with 44 cuspules. Maxilla inner corner with ~116 (left) and ~134 (right) cuspules (Fig 8D). Cheliceral promargin with 12 (left) and 13 (right) teeth (proximal to distal: first-fourth medium, fifth small, sixth-twelfth medium; first-seventh medium, eigth-thriteenth big). Sternum length 4.20. Sigillae oval, first, second and third pairs hardly visible; posterior sigilla half its length from the margin (Fig 8B).

Leg formula: IV, I, III, II,. Length of legs and palpal segments (femur, patella, tibia, metatarsus, tarsus, total): I: 9.56, 4.98, 8.29, 7.65, 5.76, 36.24. II: 8.73, 4.61, 7.82, 7.35, 5.42, 33.93. III: 8.86, 4.14, 7.37, 8.83, 5.69, 34.89. IV: 10.44, 4.46, 9.41, 13.03, 6.96, 44.33. Palp: 7.11, 4.10, 6.22, -, 5.34, 22.77. Spinnerets: PMS, 1.0 long, 0.45 apart; PLS, 2.30 basal, 1.75 middle, 2.35 distal; midwidths, 0.85 basal, 0.75 middle, 0.65 distal.

Scopulae: Tarsi I-IV entirely scopulated, III divided by narrow band of setae and IV divided by strong band of setae. Metatarsi I-II densely scopulated; III 65 % scopulated distally, IV 50 % scopulated distally.

Stridulatory setae: On palpal trochanter retrolateral face proximally, with ca. 11 spinose setae of different sizes, disorganized. Trochanter I with claviform setae on prolateral face (Fig 8E ̄F). With plumose setae on palp coxa retrolateral face, trochanter retrolateral face, femur prolateral and retrolateral faces; leg I coxa prolateral and retrolateral faces, femur prolateral face; leg II trocanter prolateral face, femur prolateral face.

Chaetotaxy (left side): femora I 2 p; II 1 p; III 2 p, 2r; IV 1 r; palp 1p; patellae none; tibiae I 2 p, 5v; II 2 p, 4v; III 2 p, 7v, 4r; IV 4 p, 10v, 7r; palp 1p, 9v; metatarsi I 2 v; II 4 v; III 5 p, 8v, 5r; IV 1 d, 7p, 12v, 12r.

Genitalia: spermatheca paired, slightly fused at the base, receptacles finger-shaped, narrower at the base and slightly bent laterally (Fig 8G).

Urticating setae: Type VI arranged in two lateral, oval patches, black in color, with well-defined margins.

Color pattern: in ethanol specimens color are brown. Live specimens are black (Fig 9D).

Distribution and natural history: Known only from Cueva de la Grieta in Huautla, Oaxaca, México (Fig 23). The species lives only inside the cave (Fig 9A ̄B); specimens were collected on rocks at a depth of 100 m from the entrance. In La Grieta also lives Hemirrhagus grieta, but this species can be only collected in deeper parts of the cave, from 200-800m below the entrance. The topography of the cave is formed by multiple pits, stretch passages and crevices (See http://www.mexicancaves.org/maps/0104).