Atmetochilus songsangchotei Kunsete & Warrit, sp. nov.

(Figs 1 A–B, 3, 4, 5, 9A–F, 10A–B, 11C; Tables 1, 2)

Material Examined. Holotype: 1 ♂ [ARA-2017-116 31/7/2015]— Phra Thaen Dong Rang Forest park, Kanchana-buri province, 14°1’41.3”N; 99°46’59.5”E, 22.9 m, CUMZ . Paratypes: 5 ♀: Thailand: Kanchanaburi province: Phra Thaen Dong Rang Forest park, 14°1’41.3”N; 99°46’59.5”E, 22.9 m : ♀ [ARA-2017-117 13/2/2017], ♀ [ARA-2017118 13/2/2017], ♀ [ARA-2017-119 13/2/2017], ♀ [ARA-2018-001 20/1/2018], ♀ [ARA-2018-010 20/1/2018], CUMZ .

Other material. 1 ♂: Thailand: Kanchanaburi province: Phra Thaen Dong Rang Forest park, 14°1’41.3”N; 99°46’59.5”E, 22.9 m : ♂ [ARA-2017-120 31/7/2015], CUMZ .

Etymology. Named after Mr. Chaowalit Songsangchote, a great spider lover, the best travelling companion, the best of our laboratory supporters.

Diagnosis. Females are most similar to those of A. fossor and can be distinguished by the carapace being dark brown (not red), no spines on the prolateral palpal patella of palp, or legs I, II (present in A. fossor). Females differ from those of A. atriceps by metatarsus I being without scopula for its length and that on metatarsus II only in its distal half (for scopula and spine characters comparisons, see Figs 9 D–L and 10A–F). Males differ those of A. koponeni, A. lehtineni and A. sumatranus by the tip of tibial spur on leg I having three straight adjacent megaspines grouped in one row on spur and differ from those of A. koponeni, A. lehtineni and A. sumatranus by the long curved embolus. Moreover, female spermathecae differ from those of A. koponeni and A. lehtineni by the head of the spermathecae being relatively longer, semicircular, dome-shaped with strong subdistal constriction.

Description. Male (holotype): Body (Fig. 3A) length 22.26.

Color in nature: Carapace, chelicerae, legs and abdomen black, abdomen covered by pale white spots and ventral abdomen and spinnerets pale white overall.

Color in alcohol: Carapace, chelicerae and legs brown, abdomen dorsally pale gray and covered with pale white spots; ventral abdomen and spinnerets pale white overall.

Carapace (Fig. 3B): 10.50 long, 9.00 wide. Chelicerae 4.30 long. Eyes (Fig. 3C): tubercle 2 rows with low mound, 4 eyes in each row; anterior row procurved; posterior row slightly recurved, almost straight. Eye size and interdistances: AME 0.36, AME-AME 0.30, ALE 0.45, ALE-ALE 1.20, PME 0.48, PME-PME 0.75, PLE 0.45, PLE-PLE 1.23, AME-ALE 0.21, AME-PME 0.18, AME-PLE 0.36, ALE-PME 0.36, ALE-PLE 0.30, PME-PLE 0 (contiguous). Eye to fovea 6.30. Fovea (Fig. 3B): strongly procurved to U-shaped. 3 rows of setae on fovea. Rastellum of about 30 robust down-curved setae on anterior margin of chelicerae. Cheliceral furrow with 9 promarginal teeth in one row, mesobasal denticles present. Fang ventrally smooth without teeth. Stridulating strikers absent. Intercheliceral tumescence absent. Labium (Fig. 3D): 1.50 long, 1.05 wide, without cuspules. Maxillae (Fig. 3D): 4.00 long, 2.00 wide; serrula absent; 20 tiny cuspules each on posterior lobe, absent on heel. Sternum (Fig. 1A): 5.00 long, 5.00 wide, posterior and medial sternal sigilla centrally confluent, anterior sigilla small, oval, on upper margin.

Spination: No spines on leg tarsi. Leg I: femur, p2; patella, 0; tibia, p4 r1; metatarsus, p1 v4 with small group of short velvet-like setae on top margin.

Tibial spur and metatarsus (Fig. 4 D–H): leg I with dense group of short dark setae at ventral base of metatarsus with subbasal bulge, tibial spur, ventral, opposing tip distally unsclerotized; tibial spur stalk- shaped with 3 straight adjacent short spines (2–3 times longer than wide) on wide digitiform or long triangular spines tip of the stalk (Fig. 4 A–C). Tibia with 2 spines on ventral, one spine on prolateral and 3 spines on retrolateral.

Leg II: tibia and patella without spines. metatarsus scopulate, v6 p1, tarsus scopula covers entire ventral, without spines. Leg III: tibia with 12 spines including, v1 r5 p2 d1; patella, r3, metatarsus with 10 spines, v5 r2 p3, tarsus scopulate ventrally. Leg IV: tibia with 12 spines, v5 r2 p5, metatarsus with 11 spines, v3 r5 p3, tarsus scopulate ventrally. Preening combs entirely absent. Legs (Table 1), formula: 1243.

Scopula: entire on tarsi I–IV and metatarsi I–II, not divided, absent on cymbium, metatarsi III–IV, tibiae I–IV, patellae I–IV and femora I–IV.

Trichobothria: one zigzag row with 12–18 per row on tarsi I–IV, one row with 6–10 on metatarsi I–IV and two rows of 6–10 on tibiae I, III; none on patellae or femora.

Claws: S-shaped row of teeth with 10 teeth per row on all paired claws.

Palp (Fig. 4 A–C); cymbium 1.60 with long setae on tip and without spines. Bulb 1.25 spherical, narrow on tip, embolus 1.65 elongated, slightly curved and sharp at tip.

Spinnerets: PMS: 1.25 long, 0.20 diameter, PLS: 4.50 long, 0.40 diameter, length of basal, medial and apical segments 1.50, 1.00, 2.00; apical segment digitiform.

Variation. The male tibial spur varies in the number of large megaspines on the tip of the spur. Another specimen (♂ [ARA-2017-120 31/7/58] has two large megaspines on the tibial spur on left leg I (Fig. 4 G–H) but three on right leg I.

Female (paratype). Body (Fig. 5A). length 28.09±4.20 (23.46–34.79).

Color in nature: Carapace, chelicerae, legs and abdomen black; abdomen covered by pale white spots and ventral abdomen and spinnerets entirely with pale white overall.

Color in alcohol: Carapace, chelicerae and legs dark brown, abdomen dorsally black with pale white spots and pale gray on ventral abdomen and spinnerets.

Carapace: (Fig. 5B): 10.33±1.19 (9.00–11.88) long, 7.94±0.73 (7.2–8.75) wide. Chelicerae 4.77±0.68 (4.136.00) long. Eyes (Fig. 5C): tubercle with 2 rows on low mound, 4 eyes on each row. Anterior row procurved, posterior row slightly recurved. Eye sizes and interdistances: AME 0.42±0.03 (0.39–0.48), AME-AME 0.15, ALE 0.65±0.05 (0.60–0.75), ALE-ALE 1.22±0.23 (0.90–1.44), PME 0.50±0.04 (0.45–0.57), PME-PME 0.75±0.24 (0.34–0.90), PLE 0.67±0.38 (0.45–1.44), PLE-PLE 1.42±0.13 (1.20–1.50), AME-ALE 0.25±0.16 (0.09–0.51), AME-PME 0.15±0.04 (0.12–0.21), AME-PLE 0.35±0.09 (0.24–0.45), ALE-PME 0.34±0.07 (0.30–0.45), ALE-PLE 0.38±0.12 (0.30–0.57), PME-PLE 0 (contiguous). Eye to fovea 6.58±0.81 (5.5–7.5). Fovea (Fig. 5B) strongly procurved to U-shaped. Setae absent in fovea. “Rastellum” of 25 robust down-curved setae on anterior margin of chelicerae. Cheliceral furrow with 8 promarginal teeth in one row, mesobasal denticles present. Fang ventrally smooth without teeth. Stridulatory strikers absent. Labium (Fig. 5D): 1.62±0.84 (1.20–3.12) long, 1.63±0.43 (0.90–1.84) wide without cuspules. Maxillae (Fig. 5D): 4.32 long, 3.00 wide with 33 cuspules each on proximal anterior lobe. Sternum (Fig. 1B): 5.55±0.62 (4.80–6.32) long, 5.19±0.49 (4.50–5.76) wide. posterior and medial sternal sigilla centrally confluent, anterior sigilla small in upper margin.

Spination and scopula: palp: tibia with 5 spines, v3 p2, tarsus scopulate, v2, leg I: Patella and femur without spines, tibia, v1, metatarsus scopula covers all, v4, tarsus scopula on ventral without spines. leg II: patella and femur without spines, tibia, v4, metatarsus scopulate on its distal half, v6, tarsus scopula covers all, without spines. leg III: tibia, r5 p2 d1, leg III: metatarsus has 17 spines, v6 r5 p4 d2, leg III: tibia, r5 p2 d1, leg III: metatarsus, p4 r6 v7. Preening combs on distal ventral metatarsi I–III. Legs (Table 2), formula: 4123.

Scopula: entire on tarsus of palp, legs I–II, relatively short, sparse cover on distal half on metatarsi II, not divided, absent on metatarsi I, III and IV, tibiae I–IV, patellae I–IV and femora I–IV.

Trichobothria: one zigzag row of 12–16 on tarsi I–IV, one row of 5–16 on metatarsi I–IV and two rows, each of 5–11 on tibiae I, III.

Claws: 1 row of teeth on prolateral face of palpal claw. 2 rows of teeth on both faces of paired claws of leg I–IV but different number per face, including 3 teeth on inner side, 4–6 teeth on outer side of Leg I–II, 2 teeth on inner side, 3–4 teeth on outer side of leg III and one tooth on inner side, 3 teeth on outer side of leg IV.

Spermathecae (ARA-2017-117) (Fig. 11C): head of spermathecae dome-shaped or semicircular with cap darkly sclerotized, neck of stalk 0.75, base separated by 1.50, stalk base wider than tip.

Spinnerets: PMS: 1.28±0.22 (1.60–2.50) long, 0.64±0.11 (0.50–0.75) diameter, PLS: 4.95±0.91 (4.16–6.45) long, 1.00±0.17 (0.80–1.25) diameter, length of basal, medial and apical segments 1.99±0.22 (1.60–2.50), 1.30±0.16 (1.15–1.50), 1.66±0.54 (0.96–2.45); apical segment digitiform.

Distribution. Known only from the type locality (Phra Thaen Dong rang Forest Park, Kanchanaburi province).

Remarks. This material was taken during field collecting from 2015–2018 in Thailand. We found Atmetochilus from Phra Thaen Dong Rang Forest Park, Kanchanaburi province (Fig. 2A). In the three visits—1 st round: 31 July 2015, 2 nd round: 11–13 February 2017 and 3 rd round: 19–20 January 2018 — 2 male individuals, 29 female individuals and 26 juvenile individuals were taken in total.