Atmetochilus atriceps Pocock, Tenasserim 1900
Creators: name: Kunsete, Chawakorn
name: Sivayyapram, Varat
name: Traiyasut, Prapun
name: Thanoosing, Chawatat
name: Khamwan, Kitiwat
name: Warrit, Natapot
Publisher: name: Zenodo
Year: 2020
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Arachnida
Araneae
Nemesiidae
Atmetochilus
Atmetochilus atriceps

description: Atmetochilus atriceps Pocock, 1900
(Figs 7, 8, 9 J–L, 10E–F, 11B)
Atmetochilus atriceps Pocock, 1900: 169. N.B.: originally described from mixed specimens identified as Damarchus oatesi Thorell, 1895; Raven, 1985: 91–92, figs 56–59.
Types: SYNTYPES: Label data: “1895.9.21.16–20. TYPE Atmetochilus atriceps Pocock, Tenasserim, Burma. E.W. OATES ”, in Pocock’s handwriting, collected from Tenasserim and preserved in NHMUK; N.B.: a holotype was not designated. The redescription of the designated lectotype supplemented with data from new material is given here (see Remarks).
Other material examined: ♀ [(ARA-2018-173) 4/5/2018], 14°2.293’N; 98°54.985’E, altitude 179 m, Warrit N., Kunsete C., Sivayyapram V., Nawanetiwong W.
Diagnosis: The female differs from those of A. fossor in the black carapace, metatarsus II without scopula and spines absent on patellae and femora I, II. Females differ from those of A. songsangchotei sp. nov. by scopula covering the distal half of metatarsus I and spines present on the palpal patella (for scopula and spine character comparisons; see Figs 9 D–L and 10A–F). The female differs from those of A. koponeni, A. lehtineni and A. sumatranus by the anterior and medial pairs of sigilla being fused with the posterior pair and spermathecae being spherical shaped anteriorly (without round head in A. koponeni, A. lehtineni and A. sumatranus and rounder than A. songsangchotei sp. nov.).
Description: ♀ LECTOTYPE (NHMUK 1895.9.21.16), the largest intact female: Habitus (Fig. 7A). Body length 25.
Color in alcohol: carapace dark brown; chelicerae black; all legs and abdomen brown.
Carapace (Fig. 7B): 10.38 long, 7.75 wide. Chelicerae 6.25 long. Eye (Fig. 7C): tubercle 2 rows on low mound, 4 eyes in each row. Anterior row procurved, posterior row slightly recurved. Eye sizes and interdistances: AME 0.53, AME-AME 0.09, ALE 0.58, ALE-ALE 1.50, PME 0.33 PME-PME 0.85, PLE 0.38 PLE-PLE 1.66, AMEALE 0.16, AME-PME 0.14, AME-PLE 0.49, ALE-PME 0.37, ALE-PLE 0.45, PME-PLE 1.08. “Rastellum” with robust spines. Eye to fovea 5.71. Fovea (Fig. 7B): strongly procurved to U-shaped. Cheliceral furrow with ca. 8 promarginal teeth. Fang ventrally smooth without teeth. Labium (Fig. 7D): labium 1.46, long 1.30 wide without cuspules, Maxillae (Fig. 7D): 3.83 long, 2.10 wide with 22 tiny cuspules each on proximal anterior lobe. Sternum (Fig. 1E) 5.63 long, 5.50 wide.
Spination: uncertain because most spines were rubbed from legs. Legs (Table 4), formula: 4123.
Remarks on Lectotype. The type specimens of A. atriceps are preserved in NHMUK, London. One of us, Chawatat Thanoosing, a Ph. D. student in Imperial College London, looked at that collection and found 7 specimens but 6 were damaged. So, we here designate the most complete specimen as a lectotype but describe a recently collected female.
Description: Female (ARA-2018-173, CUMZ), similar to lectotype except as noted. Habitus (Fig. 8A). Body length 17.56.
Color in nature: Carapace, chelicerae, legs and abdomen black, abdomen covered by pale white spots and ventral of abdomen and spinnerets with pale white overall.
Color in alcohol: Carapace dark brown; chelicerae nearly black. All legs and abdomen brown.
Carapace (Fig. 8B): 4.80 long, 6.40 wide. Chelicerae 3.00 long. Eye (Fig. 8C): tubercle with 2 rows on low mound, 4 eyes on each row. Anterior row procurved, posterior row slightly recurved. Eye sizes and interdistances: AME 0.27, AME-AME 0.09, ALE 0.39, ALE-ALE 0.90, PME 0.27, PME-PME 0.60, PLE 0.24, PLE-PLE 0.90, AME-ALE 0.12, AME-PME 0.09, AME-PLE 0.30, ALE-PME 0.15, ALE-PLE 0.09, PME-PLE 0.03. Fovea (Fig 8B): strongly procurved to U-shaped. 3 rows of setae in fovea. “Rastellum” of around 30 robust down-curved setae. Cheliceral furrow with 6 (8 in lectotype) promarginal teeth and mesobasal denticles. Fang ventrally smooth without teeth. Stridulating strikers absent. Labium (Fig. 8D): 1.25 long, 0.85 wide, without cuspules. Maxillae (Fig. 8D): 2.32 long, 1.43 wide with 20 tiny cuspules each on proximal anterior lobe. Sternum (Fig. 1D): 3.60 long, 3.00 wide. posterior and medial sternal sigilla centrally confluent, anterior sigilla separate in upper margin.
Spines and scopula: palp: tibia, p7; tarsus scopulate, v1. I: tibia, v2; metatarsus scopula cover entire, v4, Tarsus scopulate on venter, without spines. II: tarsus scopula cover entire on ventral without spines, metatarsus without scopula, v1 p5, Tibia and other segments without spines. III: patella, p3; tibia, p3; metatarsus with 19 spines, v5 r1 p9 d4; tarsus without spines and scopulate. IV: metatarsus with 15 spines, v2 r4 p9. Preening combs on both faces of distal ventral metatarsi III–IV. Legs (Table 5), formula: 4132.
Scopula: entire on tarsus of palp, relatively short, sparse cover on distal half on metatarsus I, absent on tarsi II–IV, tibiae and femora I–IV.
Trichobothria: one zigzag row of 8–12 on tarsi I–IV, one row of 6–16 on metatarsi I–IV and 5 in each of two rows on tibiae I, III.
Claws: 1 row of teeth on prolateral face of palpal claw; 2 rows of teeth on both faces of pair claws of I–IV but differing in number, including 3 teeth on inner side, 5 teeth on outer side of I, 2 teeth on inner side, 5 teeth on outer side of II–III and two teeth on inner side, 3–4 teeth on outer side of IV.
Spermathecae (Fig. 11B): head of spermathecae spherical, stalk 0.51 mm, base 1.00, stalk base and tip of equal width.
Spinnerets: PMS 1.25 long, diameter 0.30. PLS: 3.10 long, 0.50 diameter. length of basal, medial and apical segments 1.25, 0.75, 1.10. apical segment digitiform.
Distribution: known only from type locality, Tenasserim mountain Range, Myanmar.
Remarks: Because the lectotype was examined by only one of us, we present the partial data from the lectotype and also fully describe fresh material.
In Dawei, Myanmar, from 2–4 May 2018, we found one female Atmetochilus individual living in a burrow on a roadside bank (Fig. 1C). By locality, size and scopula similarities with the lectotype, we diagnosed it as A. atriceps and gave it a registration number/code CUMZ ARA-2018-173.
description: Published as part of Kunsete, Chawakorn, Sivayyapram, Varat, Traiyasut, Prapun, Thanoosing, Chawatat, Khamwan, Kitiwat & Warrit, Natapot, 2020, Records and redescription of a mygalomorph spider genus ignored for over 100 years with a new species: the genus Atmetochilus Simon, 1887 (Araneae Nemesiidae) in Thailand, pp. 521-543 in Zootaxa 4819 (3) on pages 534-538, DOI: 10.11646/zootaxa.4819.3.5, http://zenodo.org/record/4397082