Superficially, a typical genus of Cryptodesmidae, distinguished from other genera in the following combination of characters, the gonopodal ones being the most important.

Body small- to medium-sized (ca 8–21 mm long, ca. 1.7–5.5 mm wide), with 20 segments. Collum flabellate, much broader than head, fully covering it from above; eleven radii at collum’s fore margin dividing it into 12 (sub)equal sectors; dorsal surface tuberculate to areate. Metaterga distinctly tuberculate to areate, usually setose, with at least two irregular transverse rows of tuberculations extending onto paraterga. The latter very short and very wide, subhorizontal, multilobulate at least at caudal and lateral margins. Ozopores highly variable, usually untraceable, when present then barely visible, located near base of paraterga either entirely dorsally or partly dorsally and mainly ventrally, or entirely ventrally. Only coxae 7 or both coxae 6 and 7 distinctly separated to accommodate tips of gonopods. Gonopod aperture usually subcordiform, edges with little or no elevation.

Gonopods ranging from rather simple to relatively complex (Fig. 4), small, usually foliate and held subparallel to each other; telopodites short to rather short, only slightly longer than coxae; the latter usually either bare or poorly setose, more rarely densely setose. Cannula usual, long, slender and falcate, normally not subtended by a median projection of coxa. Prefemoral (setose) part of telopodite making up 1/3–1/2 of the whole; acropodite either distinctly branched (usually with three branches, including an inconspicuous solenomere) or more or less deeply notched apically, seminal groove running entirely on mesal face to end on a more or less distinct caudo-apical solenomere.

Cryptodesmus bicolor Pocock, 1894, by original designation.

T. doriae Pocock, 1895, T. feae Pocock, 1895, T. watsoni Pocock, 1895, T. kometis (Attems, 1938), T. latellai Golovatch, Geoffroy, Mauriès & VandenSpiegel, 2010, T. cavernicola Golovatch, 2016, T. muratovi Golovatch & VandenSpiegel, 2017, T. bellus Liu, Golovatch & Tian, 2017, T. intricatus Liu, Golovatch & Tian, 2017 and T. reflexus Liu, Golovatch & Tian, 2017.

West Sumatra, Singkarah, 1,800 m a.s.l. (Pocock 1894; Jeekel 1955); Anai Cleft, 500 m a.s.l. (Jeekel 1955).

Yado, Carin Asciuii Cheba, 1,200–1,300 m a.s.l. (Pocock 1895; Attems 1936).

Village of Chiala, Carin Asciuii Ghecù, 1,200–1,600 m (Pocock 1895); Between Namkham and Kwangmu, 2,500 feet; Mule track between Hosi and Mio-Hsao, 3,700–4,400 feet; and North Shan States (Attems 1936).

Chin Hill (upper Burma) (Pocock 1895) and Waseru Choung River, south boundary of North Arakarn; India: Assam, Gauhati (Guwahati); Samagutung; Mangaldai district; Eastern Himalayas, Darjeeling district, Pashok; Bengal, Howrah opposite Calcutta (= Kolkata); Bangladesh: Chittagong Hills Tracts, Shishgk Valley (Attems 1936).

Khanhhoa Province, Mt Hon Ba (Nhatrang); Lam Dong Province, Mt Diling, 1,000 m a.s.l. (S. Annam); Dalat (S. Annam), 1,500 m a.s.l.; Dalat, Camli, 1,500 m a.s.l.; Peak Langbian; Danang Province, Mt Bana, 1,400 m a.s.l. (Attems 1938); Lamdong Province, Peak Langbian; Dalat; Danang Province, Mt Bana, 1,500 m a.s.l.; Laocai Province, Mt. Fanxipan; Laichau Province, Laichau (Attems 1953); Lam Dong Province, Dalat, Peak Lang Bian, below summit (ca 2,030 m a.s.l.), (Golovatch et al. 2010); Laos: Xiang Khouang Province, Xieng Khouang; Luang Prabang Province, Luang Prabang; Sainyabuli Province, Paklay; Champasak Province, Bolaven Plateau; Cambodia: Kratie Province, Kratie (Mekong) (Attems 1953).

Guizhou Province, Qianxi County, Hong Lin Town, Cave Chang Tu Dong; Cave Tiao Shuz Dong (Golovatch et al. 2010).

Khammouane Province, Ban Naden, Cave Tham Namlat, 17.504969°N, 105.385598°E, ca. 180 m a.s.l. (Golovatch 2016) and ca. 65 km north of Thakaek, Cave Tham Nam Lod (Golovatch & VandenSpiegel, 2017).

Xieng Khoung Province, ca. 9 km northwest of Vieng Thong, secondary tropical forest, 20°08.466'N, 103°20.099'E, ca. 870–910 m a.s.l. (Golovatch and VandenSpiegel 2017).

Yunnan Province, Qujing City, Luoping County, Machang village, Cave Shuiyuan Dong, 24°49'33"N, 104°21'48"E, 1,530 m a.s.l. (Liu et al. 2017).

Yunnan Province, Kunming City, Shilin County, Guishan Town, Cave Haiyi I Dong, 24°38'50"N, 103°32'49"E, 1,890 m a.s.l. (Liu et al. 2017).

Hunan Province, Chenzhou City, Linwu County, Xianghualing Town, Cave II Dong (Liu et al. 2017).

Holotype ♂ (CUMZ), China, Yunnan Province, Xishuangbanna County, Mengla, 213 National Road, near Menglunzhen, Munlun village, 578 m a.s.l., 21°56'40"N, 101°13'45"E, 25.10.2016, leg. J. Sutcharit & S. Panha.

2 ♂♂, 1 ♀ (CUMZ), 1 ♀ (ZMUM), same locality, together with holotype.

Honours Jirasak Sutcharit (CUMZ), one of the collectors.

This new species seems to be particularly similar to T. bellus Liu, Golovatch & Tian, 2017 and T. intricatus Liu, Golovatch & Tian, 2017, both from caves in southern China (Liu et al. 2017), since they all are distinguished by the presence of abundant long setae on the lateral face of the gonopodal coxae, and by highly complex gonopodal telopodites. However, T. sutchariti sp. n. differs from them, as well from all other congeners in that its gonopodal telopodites are noticeably curved caudolaterad, and there is a strong, curved, laterally densely setose process (cxp) on each of the gonopodal coxae (Fig. 4).

Length 13.9–15.2 (♂) or 14.2–14.5 mm (♀), width of midbody pro- and metazona 1.7–1.9 and 4.8–5.1 mm (♂) or 1.8–2.0 and 4.4–5.2 mm (♀), respectively.

Colouration of live animals uniformly whitish yellow (Fig. 1A), sometimes light red-brownish mid-dorsally (Fig. 1B); head, legs and venter whitish yellow to pallid, antennae light brown, increasingly infuscate distally; colouration in alcohol, after eight months of preservation, entirely pallid, only antennae still infuscate (brown) distally.

Clypeolabral region and vertex densely pilose, epicranial suture distinct. Antennae rather short and clavate (Figs 1B, 2A, B), reaching segment 3 (♂, ♀) when stretched laterally or ventrolaterally; in length, antennomere 6 > 3 > (4 = 2) > 5; antennomeres 5–7 each with a compact apicodorsal group of bacilliform sensilla (Fig. 2C). Body with 20 segments (Fig. 1A, B), composed of collum plus 17 podous and one apodous ring, plus telson. In width, head << collum < segment 2 <3 < 4 <5–17; thereafter body rapidly tapering towards telson (Fig. 3H).

Tegument dull, prozonae finely shagreened (Figs 2E, I, 3M); metaterga densely tuberculate and setose (Figs 2D, E, F, 3A, B, E, H). Fore and caudolateral margins of collum, as well as anterolateral, lateral and caudal margins of following paraterga evidently crenulate-lobulate, these lobulations being slightly larger at caudal margins of paraterga (Figs 2D, 3A, H).

Collum completely covering the head from above, regularly convex at fore margin, concave caudally, tuberculations arranged in 8–9 irregular transverse rows of evident setigerous knobs with abundant spherical granulations (Fig. 2D); caudal corner of paraterga narrowly rounded, declined ventrad, but not projecting beyond rear tergal margin (Fig. 2A).

Dorsum convex, postcollum paraterga flat, very broad and long, narrowly rounded laterally, evidently and regularly declivous and continuing the outline of dorsum; anterior edge straight, rib-shaped, forming a distinct shoulder, abundantly microgranulate and micropilose (Fig. 3C); tips of paraterga reaching level of venter, directed increasingly caudolaterad starting with segment 14, drawn behind rear tergal margin on segments 16–18 and strongly curved caudad on segment 19 (Fig. 3H); metatergal tuberculations arranged in 5–6 irregular transverse rows of small, round, setigerous knobs surrounded with abundant spherical granulations, these partly extending onto paraterga (Figs 2E, I, 3E, F, G); tergal setae rather short, slender and simple, mostly retained in caudal row on each metatergum (Fig. 2E), macrochaetae absent.

Limbus a row of simple, relatively short, tongue-shaped protuberances, abundantly microdenticulate apically (Fig. 2E, H). Ozopores invisible, pore formula untraceable. Pleurosternal carinae with complete crests only on segments 2 and 3 (♀) or with a sharp caudal tooth on segments 2 and 3, but segment 4 with a small rounded denticle (♂), thereafter absent.

Axial line absent. Stricture dividing pro- and metazonae broad, shallow and smooth, with abundant spherical granulations dorsally and microgranulate laterally (Fig. 3E).

Epiproct (Fig. 3H, L) conical, flattened dorsoventrally, microtuberculate, with four strong apical papillae. Hypoproct roundly subtrapeziform (Fig. 3I), 1+1 caudal setae clearly separated, borne on small, but evident knobs.

Sterna usual, sparsely setose, without modifications, cross-impressions evident (Fig. 3I).

Legs very long and slender, without modifications (Figs 2G, 3I), ca. 1.3–1.4 times as long as paratergal width (♂, ♀) (Figs 1–3); in length, femora = tarsi >> prefemora > tibiae > coxae and postfemora (Fig. 2G); gonapophyses on ♂ coxae 2 small cones; neither adenostyles nor tarsal brushes present. Gonopod aperture transversely ovoid, caudal and lateral margins thin, only slightly elevated (Fig. 2A).

Gonopods (Figs 2A, 3J, K, 4) complex. Each coxa with a conspicuous, high, curved, laterally densely setose process (cxp). Telopodite stout, clearly curved caudolaterad (Fig. 3J), approximately twice as long as coxal process, divided by a notch, but compact apically (Fig. 4).

All five specimens were taken from a rather large population found on limestone rocks, as well as on tree trunks during the rainy season. It seems noteworthy that the surface structures illustrated in the new species, such as the sculpture of the prozonae and the shape of the limbus (Fig. 2H, I), perfectly match the findings of Akkari and Enghoff (2011) in other genera/species of the same family.