Attems (1938) described this species as Glyphiulus dubius, based on a single female (holotype) collected at Angkor, Cambodia. Mauriès (1983) regarded this species as being very similar to P. boutini Mauriès, 1970. The major difference is that P. dubius has dorsal crests divided into three tubercles starting with body segment 6, vs body segment 7 in P. boutini. However, the status of the species is still doubtful, as the gonopodal structure remains unknown. Hoffman (1977) called for a search of male topotypes to clarify the species’ identity.

4 ♂, 5 ♀ (CUMZ-CAM185), Cambodia, Kampot Province, Kampong Trach, Phnom Kampong Trach Cave Temple (locality code C043), 510 m, 10°34'2"N, 104°28'6"E, 15.09.2019, leg. E. Jeratthitikul and R. Srisonchai. 5 ♂ (CUMZ-CAM184), Cambodia, Kampot Province, Banteay Meas, Prasat Phnom Totong Temple (locality code C042), 510 m, 10°41'49"N, 104°31'21"E, 15.09.2019, leg. E. Jeratthitikul and R. Srisonchai.

Length of adult 24.3–37.2 mm (♂) or 31.2–38.5 mm (♀); width of midbody 1.3–1.7 mm (♂) or 1.4–1.9 mm (♀).

Coloration of live animals light brown to light yellow-brown (Fig. 1A) with lighter anterior and posterior parts of body; antennae, venter and legs light yellowish; coloration in alcohol, after six months of preservation, uniformly red brownish to dark brown, dorsal crests and porosteles usually dark brownish. Antennae and venter yellow brownish to brownish. Eyes brown to blackish.

Adult body with 54–66p+2–4a+T (♂) or 57–65p+1–4a+T (♀). Eye patches transversely ovoid, with 6–11 flat ommatidia arranged in three longitudinal rows. Clypeus with three teeth anteromedially. Carinotaxic formula of collum: 1a/(t)+2p/(t)/(t)+3p/(t)+4p/(t)/(t)/t/t+ta/t+5p/t/(t)/t/t/t+pp/t/(t)/t/t+ta/t+m/m.

The new specimens fully agree with the original description (Mauriès 1970), which was sufficiently detailed and beautifully illustrated. Instead, we only present a few notes on variation and a new illustration (Fig. 1A) to show coloration based on live material.

This species was originally described from near Kampong Trach, 10.554N, 104.471E, Kampot Province, Cambodia (Mauriès 1970). The new material was taken from the Phnom Kampong Trach Cave and Prasat Phnom Totong Temple, both situated approximately 17 km away from the type locality.

Holotype ♂ (CUMZ-CAM183), Cambodia, Kampot Province, Tuek Chhou District, Phnom Kbal Romeas Cave (locality code C045), 10°37'0"N, 104°14'38"E, 16.08.2019, leg. E. Jeratthitikul and R. Srisonchai.

Paratypes. 2 ♂, 3 ♀ (CUMZ-CAM183), 1 ♂, 1 ♀ (ZMUM), 1 ♂, 1 ♀ (NHMD), 1 ♂, 1 ♀ (ZRC), same locality, together with holotype.

To emphasize the telopodites of the posterior gonopods being clearly serrate apicolaterally; adjective.

This new species is distinguished from all congeners by its anterior gonopod structure: in having only a pair of single coxosternal processes (cxp) (Fig. 3H, I) it is especially similar to that observed in P. hoffmani Golovatch, Geoffroy, Mauriès & VandenSpiegel, 2009, but both these species differ in cxp being smooth and distally curved in P. biserratus sp. nov. vs serrate and suberect in P. hoffmani. The posterior gonopods of P. biserratus sp. nov. are unique in showing laterally fringed/serrate telopodites (te), both elongate and membranous (Fig. 3J, K), and ♂ legs 1 with very long, slender and one-segmented telopodites (Fig. 3D, E).

Length of holotype ca 24 mm; adult paratypes 21.5–26.2 mm (♂) or 21.5–32.8 mm (♀); midbody segments round in cross-section (Fig. 2F), their width (horizontal diameter) and height (vertical diameter) similar, width in holotype 1.4 mm; paratypes 1.3–1.5 mm (♂) or 1.4–1.8 mm (♀).

Coloration of live animals light brown (Fig. 1B) with lighter anterior and posterior parts of body; antennae, venter and legs light yellowish; coloration in alcohol, after six months of preservation (Fig. 2), uniformly red-brownish or dark castaneous brown to grey-brown, dorsal crests and porosteles usually dark brownish. Antennae and venter yellow-brownish to brownish (Fig. 2A–C, E–G, I). Eyes brown to blackish (Fig. 2A, C).

Adult body with 43p+4a+T (holotype); paratypes with 43–53p+2–5a+T (♂) or 50–58p+2–3a+T (♀). Eye patches transversely ovoid, with 7–11 rather flat ommatidia arranged in three longitudinal rows (Fig. 2A, C). Clypeus with three teeth anteromedially (Fig. 2C).

Antennae short and clavate (Figs 1B, 2A, C, 3C), extending behind segment 4 laterally, antennomeres 5 and 6 each with a small apicodorsal field or corolla of bacilliform sensilla (Fig. 3C). Gnathochilarium oligotrichous, each lamella lingualis with four or five setae; promentum bare, separated from eumentum by a distinct suture (n = 2) (Fig. 3A).

Postcollum constriction evident, but collum moderately enlarged (Figs 1B, 2A–C). Carinotaxic formula of collum: (1a)/t+2p/t+3p/t+4p/t/t+ta/t+5p/t/t+ta/t+pp/t/t+m/m (Figs 2A–C, 3B). Carinotaxy of metatergum 2, 8/8+m/m+8/8; of metaterga 3 and 4, 7/7+m/m+7/7 (Fig. 2A, B); formula on metaterga 5 and following metaterga, except last few, usually 3/3+I/i+3/3/3+m/m+3/3/3+I/i+3/3 (Fig. 2A, B, D–H); of legless segments/rings, usually 7+m+7 (Fig. 2G, H); all crests and tubercles, including poriferous cones, rather low. Dorsal crests on several posteriormost segments slightly lower than others (Fig. 2A, B, D–H). Midbody segments ovoid in cross-section, almost not compressed laterally (Fig. 2F). Porosteles large, rather low, conical, round, directed caudolaterad, higher than wide (Fig. 2D–F).

Tegument finely alveolate-areolate (Fig. 2A, B, D, E, G, H), dull throughout. Metatergal setae absent. Pleural regions of segments 2–4 conspicuously elongated, flap-shaped, especially clearly so on segment 3 (Fig. 2A, C). Limbus very finely and rather regularly denticulate, thin (Fig. 2A, B, D, E, G, H).

Epiproct (Fig. 2G–I) broadly rounded apically, with 2+2 paramedian tubercles, median tubercles being higher than lateral ones. Paraprocts rather clearly flattened, each with a faint premarginal sulcus medially (Fig. 2G, I). Hypoproct clearly emarginate at caudal margin (Fig. 2I).

Ventral flaps behind gonopod aperture on male segment 7 distinguishable as low swellings with rounded flaps bent abruptly caudad.

Legs short, nearly as long as body diameter (Figs 2F, 3L), claw at base with a strong, spiniform, accessory claw almost half as long as claw itself (Fig. 3L).

Male legs 1 with a usual strong and long central hook (actually a pair of tightly appressed hooks) regularly curved forward; a pair of strong, sac-shaped, one-segmented telopodites, the latter being nearly as long as central hook (Fig. 3D, E).

Male legs 2 strongly enlarged, with high and large coxae; telopodites hirsute on anterior face; penes broad, oblong-subtrapeziform, fused at base (Fig. 3F).

Male legs 3 modified as usual, with particularly elongate and slender coxae, and shortened telopodites (Fig. 3G).

Anterior gonopods (Fig. 3H, I) simple, coxosternum halves being touching but not really fused medially; each coxite bearing only a single, digitiform, coxosternal process (cxp) with an unciform and laterad directed tip, and a few strong setae medially near base; telopodites (te) simple, lateral in position, movable, one-segmented, digitiform, rounded and bearing several apical setae at tip, shorter than cxp.

Posterior gonopods (Fig. 3J, K) highly compact, simple, coxosternum also contiguous, but not fused medially; each coxite with a long, slender, distally slightly curved, paramedian, coxal process (pp); anterior coxal process (ap) suberect, distally with three long, slender, flagelliform branches differing in length; telopodite (te) elongate, membranous, laterally clearly fringed/serrate, distinctly shorter than both pp and ap, with a parabasal roundish field of microsetae on anterior face.

Holotype ♂ (CUMZ-CAM186), Cambodia, Kep Province, Damnak Chang’aeur District, Ou Krasar, Phnom Sorsia Temple (locality code C047), 10°33'54"N, 104°17'2"E, 16.09.2019, leg. E. Jeratthitikul and R. Srisonchai.

Paratypes. 16 ♂, 17 ♀, 6 juveniles (CUMZ-CAM186), 2 ♂, 2 ♀ (ZMUM), 2 ♂, 2 ♀ (NHMD), 2 ♂, 2 ♀ (ZRC), same locality, together with holotype.

To emphasize “khmer”, referring to the main people of Cambodia; a noun in apposition.

This new species differs from all congeners by all crests on the collum being undivided, mostly complete (Fig. 5B) and male legs 1 with very long and one-segmented telopodites (Fig. 5D, E), as well as by the presence of 2+2 paramedian, characteristically long, slender, coxosternal processes of the anterior gonopods, a shorter and only apically curved posterior (cxp1) pair, and a longer, mesally micropapillate and regularly curved anterior (cxp2) one (Fig. 5H, I); the posterior gonopods are oblong-subtrapeziform, membranous, each with a small apical spike (d) and a bifid process (k) at about 1/3 telopodite length on anterior face (Fig. 5J, K).

Length of holotype ca 26 mm; adult paratypes 19.3–25.4 (♂) or 14.1–27.0 mm (♀), juveniles 8.5–11.5 mm long; midbody segments round in cross-section (Fig. 4F), their width (horizontal diameter) shorter than height (vertical diameter), width in holotype 1.2 mm; paratypes 1.1–1.5 (♂), 1.1–1.6 mm (♀) or 0.8–1.1 mm (juveniles).

Coloration of live animals light brown to chocolate brown (Fig. 1C) with blackish or dark brown anterior and posterior parts of body; antennae light brown to brown; venter and legs light yellowish to yellowish white; rather contrasting dark brownish, lateral, longitudinal stripes above ozopores on each side, both interrupted mid-dorsally by a light wide axial stripe; ommatidia brown to blackish (Fig. 4A, C); coloration in alcohol, after six months of preservation (Fig. 4), similar to live one, but body red-brownish or dark castaneous brown to grey-brown; vertex dark brown to yellow-brown; antennae dark brown to blackish; venter and legs light yellowish to yellowish red (Fig. 4A–C, E–G, I).

Adult body with 53p+2a+T (holotype); paratypes with 46–57p+1–3a+T (♂), 44–55p+2–4a+T (♀) or 35–42+3–4a +T (juveniles). Eye patches transversely ovoid, with 11–18 ommatidia arranged in three or four longitudinal rows (adult) (Fig. 4A, C) or with 6–10 ommatidia in three longitudinal rows (juveniles). Clypeus with three teeth anteromedially (Fig. 4C).

Antennae short and clavate (Figs 1C, 4A, C, 5C), extending behind segment 3 laterally, antennomeres 5 and 6 each with a small apicodorsal field or corolla of bacilliform sensilla (Fig. 5C). Gnathochilarium oligotrichous, each lamella lingualis with two or three setae; promentum bare, separated from eumentum by a distinct transverse suture (n = 2) (Fig. 5A).

Postcollum constriction evident, but collum only moderately enlarged (Figs 1C, 4A–C). Carinotaxic formula of collum: 1+ta+2+3+4+ta+5(5p/t)+ta+P+ma (Figs 4A–C, 5B). Carinotaxy of metatergum 2, 8/8+m/m+8/8; of metaterga 3 and 4, 7/7+m/m+7/7 (Fig. 4A, B); formula of metaterga 5 and following metaterga, except last few, usually 3/3+I/i+3/3/3+m/m+3/3/3+I/i+3/3 (Fig. 4A, B, D–H); of legless segments, usually 7+m+7 (Fig. 4G, H); all crests and tubercles, including poriferous cones, rather low. Dorsal crests on several posteriormost segments lower than others (Fig. 4A, B, D–H). Porosteles large, low, conical, round, directed caudolaterad, wider than high (Fig. 4D–H).

Tegument finely alveolate-areolate (Fig. 4A, B, D, E, G, H), dull throughout. Metatergal setae absent. Pleural regions of segments 2–4 conspicuously elongated, flap-shaped, especially well so on segment 3 (Fig. 4A).

Epiproct (Fig. 4G–I) broadly rounded apically, with 2+2 small, paramedian tubercles at midway. Paraprocts rather clearly flattened, each with a faint premarginal sulcus medially (Fig. 4G, I). Hypoproct clearly emarginate at caudal margin (Fig. 4I).

Ventral flaps behind gonopod aperture on male segment 7 evident, distinguishable as rather high swellings with rounded flaps bent abruptly caudad (Fig. 4C).

Legs short, on midbody segments about 1/3 as long as body diameter (Figs 4E–G, 5L), claw at base with a strong, spiniform, accessory claw about 1/3 as long as claw itself (Fig. 5L).

Male legs 1 with a usual, strong, central hook (actually a double structure of tightly appressed hooks), regularly curved forward; a pair of 1-segmented, sac-shaped and very long telopodites, the latter almost as long as central hook (Fig. 5D, E).

Male legs 2 strongly enlarged, with very high and large coxae; telopodites hirsute on anterior face; penes subconical, truncate apically, fused at base (Fig. 5F).

Male legs 3 modified as usual, with particularly elongate and slender coxae and shortened telopodites (Fig. 5G).

Anterior gonopods (Fig. 5H, I) rather complex, with 2+2 paramedian, long, slender, coxosternal processes: a shorter and only apically curved posterior (cxp1) pair, and a longer, mesally micropapillate and regularly curved anterior (cxp2) one (Fig. 5H, I); telopodites (te) finger-shaped, subcylindrical, long, apically setose, about as high as cxp2, attached to coxal region caudolaterally, probably capable of movement.

Posterior gonopods (Fig. 5J, K) rather long (high), simple; coxites well-separated from sternum, fused only basally, oblong-subtrapeziform, membranous, with traces of telopodites in the form of a small, latero-parabasal field of microsetae on posterior face of each gonopod; each coxite with a terminal medial spike (d), a subterminal lobule at d base, and a small bifid process (k) at about 1/3 coxite length on frontal face; distal half lamellose, fringed and with a deep fovea subapically.

This species was found together with a single male specimen of Orthomorpha coarctata (De Saussure, 1860).