Holotype ♂ (CUMZ), Laos, Luang Prabang Province, Chomphet District, Kacham Waterfall, 442 m a.s.l., 19°38'57"N, 100°04'52"E, 30.08.2014, leg. C. Sutcharit and R. Srisonchai.

Paratypes. 4 ♂, 7 ♀ (CUMZ), 1 ♂, 2 ♀ (ZMUM), same locality, together with holotype. 4 ♂, 1 ♀ (CUMZ), same District, small waterfall near road, 405 m a.s.l., 19°41'54"N, 102°07'52"E, 01.07.2014, leg. R. Srisonchai.

To emphasize the obvious similarities to G. bedosae Golovatch, Geoffroy, Mauriès & VandenSpiegel, 2007.

This new species is particularly similar to G. bedosae, with which it shares the following diagnostic characters: the presence of a row of several strong setae near the median marginal ridge on the paraprocts, combined with the gnathochilarium being considerably less densely setose on the caudal face, and the anterior gonopods showing a pair of smaller apical. It differs from G. bedosae primarily by the larger lateral teeth on the coxosternal plate. See also Key below.

Length of holotype ca 12.1 mm; that of paratypes 12.1–23.1 (♂) or 12.2–18.3 mm (♀); midbody segments round in cross-section (Fig. 2L), their width (horizontal diameter) and height (vertical diameter) similar, width of holotype 1.0 mm, of paratypes 0.8–1.5 (♂) or 0.9–1.2 mm (♀).

Coloration of live animals brownish yellow (Fig. 1A, B); unfaded specimens variegated, with contrasting dark brownish, lateral, longitudinal stripes above ozopores on each side, both interrupted mid-dorsally by a light wide axial stripe; vertex dark brown, anterior half of collum blackish to dark brown; venter, legs and telson light yellowish to brownish yellow; ocellaria blackish; coloration in alcohol similar, but body brownish yellow to light brownish; vertex dark brown to brown, anterior halves of both collum and head light brown to dark brown; eyes blackish to brownish.

Body with 50p+2a+T segments (holotype); paratypes with 39–58p+2(3)a+T (♂) or 41–47p+2–4a+T (♀) segments. Eye patches transversely ovoid, each composed of 10–18 rather flat ocelli in 4 or 5 irregular longitudinal rows (Fig. 2D). Antennae short and clavate (Figs 1A, 2A, D, E), extending behind segment 3 laterally, antennomeres 5 and 6 each with a small distoventral group or corolla of bacilliform sensilla (Fig. 2F, G). Gnathochilarium with a clearly separated promentum (Figs 2E, 4B).

Head width = segment 2 < collum = midbody segment (close to 13th to 15th) > segment 3 = 6 > 4 < 5 < 7 < 8 = 10; body abruptly tapering towards telson on a few posteriormost segments (Fig. 2P). Postcollar constriction very evident (Fig. 2B).

Collum with 7+7 longitudinal crests starting from anterior edge, but both median crests interrupted in about caudal 1/2–1/3, being replaced there by similar 1+1+1 crests; carinotaxy formula 1–6+7a+pc+ma (Fig. 2B, C).

Following metaterga similarly strongly crested (Figs 1A, 2A–C, H, I, O, P), especially from segment 5 on, whence enlarged porosteles commence, these becoming completely absent from legless segments due to loss of ozopores (Fig. 2P). Porosteles large, conical, round, directed caudolaterad, wider than high (Fig. 2N). Midway metatergal crests on segment 5 distinctly divided into two at about 1/3 of metatergal height, each half rather evident and well rounded, nearly undivided and small tubercles in their stead in legless segments in front of telson (Fig. 2B, I, O, P). Carinotaxy formulae 3+I+4+I+3 and 3+i+3+i+3, the former standing for frontal row of crests, the latter for caudal one, both fairly independent (Fig. 2A–C, H, I, O, P).

Tegument extremely delicately and quite sparsely alveolate-areolate (Fig. 2K), dull throughout. Fine longitudinal striations in front of stricture between pro- and metazona, remaining surface of prozona very delicately shagreened (Fig. 2J). Metatergal setae absent. Segments 2 and 3 each with long pleural flaps. Limbus extremely finely and regularly spiculate (Fig. 2K). Epiproct (Fig. 2O–Q) simple, regularly rounded caudally, faintly convex medially. Paraprocts regularly convex, each with premarginal sulci medially and with a row of several strong setae at medial margin (Fig. 2Q). Hypoproct transversely bean-shaped, slightly concave caudally, with 1+1 strongly separated setae near caudal margin (Fig. 2Q).

Ventral flaps behind gonopod aperture on ♂ segment 7 barely distinguishable as low swellings forming no marked transverse ridge.

Legs short, on midbody segments about 2/3 length of body height (Figs 2A, H, M, O, 4D). Claw at base with a strong accessory spine almost half as long as main claw (Fig. 4D). Tarsi and tarsal setae very delicately fringed.

♂ legs 1 highly characteristic (Figs 3A–C, 4C) in being very strongly reduced, represented only by a sternum devoid of any median or paramedian structures, but carrying 1+1 strongly separated prongs, both evidently curved posteriad and bearing several strong setae and rudimentary, 2-segmentel leg vestiges at base on caudal face (Figs 3B, C, 4C).

♂ legs 2 very slightly hypertrophied (Figs 3D, E, 4F), only claw and, anteriorly, coxa somewhat reduced; penes broad, oblong-subtrapeziform, each with 4–6 strong setae distolaterally (Figs 3D, E, 4D).

♂ legs 3 modified in having coxa especially slender and elongate (Figs 3F, 4G).

Anterior gonopods (Figs 3G–J, 4E) with a typical shield-like coxosternum which is rather sparsely microsetose on caudal face (Fig. 3H, J) and shows its inner, somewhat elevated, axe-shaped processes, as well as small, but obvious, apicolateral teeth. Telopodite small, but movable, 1-segmented, lateral in position, with 2 or 3 strong apical setae and a field of microsetae at base (Fig. 3H, I), modestly higher than adjacent lateral corner of coxosternum.

Posterior gonopods (Figs 3K–P, 4H, I) compact, broadly subquadrate, coxite medio-apically with a long, plumose, apical flagellum (f) (Fig. 3M, N) with evident spikes paramedially (Fig. 3K–O); caudal piece (telopodite) (b) microsetose laterally, both b and strongly setose lobes (l), lower than frontal, microsetose, median piece (a).

The granulatus-group currently encompasses 34 described species. The above new one is only the second species in this group to be reported from Laos. Two populations have been found, each from near a forest at a waterfall, and both show the remarkable colour pattern as described above.

Holotype ♂ (CUMZ), Laos, Luang Namtha Province, Viengphoukha District, Kao Rao Cave, 737 m a.s.l., 20°43'30"N, 101°09'04"E, 12.10.2014, leg. C. Sutcharit and R. Srisonchai.

Paratypes: 6 ♂, 16 ♀, 8 juveniles (CUMZ), 1 ♂, 2 ♀ (ZMUM), same locality, together with holotype.

To emphasize the obvious similarities to G. costulifer Golovatch, Geoffroy, Mauriès & VandenSpiegel, 2007.

This new species is particularly similar to G. costulifer, with which it shares the following diagnostic characters: the unique carinotaxy formulae, coupled with anterior gonopod structural details. It differs from G. costulifer by the more sparsely alveolate background fine structure of the metazonae, coupled with the gnathochilarium being considerably less densely setose on the caudal face, the paramedian coxal prongs on ♂ legs 1 much stronger and their telopodites 4-segmented, the apicoparamedian sternal projections on the anterior gonopods slightly longer and more slender, and the flagella of the posterior gonopods much longer. See also Key below.

Length of holotype ca 19.4 mm; adult paratypes 17.2–25.3 (♂) or 17.5–25.6 mm long (♀), juveniles 1.34–1.79 mm long; midbody segments round in cross-section (Fig. 5L), their width (horizontal diameter) and height (vertical diameter) similar, width in holotype 1.4 mm; paratypes 1.1–1.5 (♂), 0.9–1.5 (♀) or 0.9–1.1 mm (juveniles).

Coloration of live animals dark brown to red-brownish (Fig. 1C), with contrasting light yellow head, antennae, collum, segments 2 and 3, sometimes segment 4 as well; telson yellow-brown, venter and legs brownish yellow to brownish red, ocellaria blackish, lateral longitudinal stripes above porosteles brownish; a thin axial line traceable due to darker median crests, sometimes body uniformly yellowish to brownish yellow (Fig. 1D); coloration in alcohol, after three years of preservation similar, but telson light brownish, venter and legs brownish yellow to brownish, lateral longitudinal stripes brownish to brownish red.

Body with 52p+4a+T (holotype); paratypes with 52–67p+2–4a+T (♂), 49–60p+2–4a+T (♀) or 41–50+5a+T (juveniles). Eye patches transversely ovoid, each composed of 7–11 blackish, rather flat ocelli in 4 or 5 irregular longitudinal rows (Fig. 5D). Antennae short and clavate (Figs 1C, D, 5A–E, 7A), extending behind segment 3 laterally, antennomeres 5 and 6 each with a small distoventral group or corolla of bacilliform sensilla (Fig. 5F, G). Gnathochilarium with a clearly separated promentum (Figs 5E, 6B, 7B).

Head width = segment 2 < collum = midbody segment (close to 8^th to 10^th) > segment 3 = 5 > 4 < 7 < 8 = 10; body abruptly tapering towards telson on a few posteriormost segments (Fig. 5P). Postcollar constriction very evident (Fig. 5B).

Collum nearly smooth, carinotaxy formula 1+2c+3–4+5c+6a+pc+ma (Fig. 5A–C), with 6+6 longitudinal crests starting from anterior edge, but both median crests interrupted in about caudal 2/3–3/4, being replaced there by similar 1+1+1 crests.

Following metaterga similarly strongly crested (Figs 1C, D, 5A–C, H, I, O, P), especially from segment 5 on, whence porosteles commence (Fig. 5A, B), smaller tubercles in their stead on legless segments in front of telson due to loss of ozopores (Fig. 5P). Porosteles large, conical, round, directed caudolaterad, wider than high (Fig. 5N), ozoporiferous crests distinctly divided into two about midway, their frontal halves being higher (Fig. 5A, B, H, I, O, P). Carinotaxy formulae 2+I/i+3/3+I/i+2 on segments 2–3, as well as on the last 1–2 leg-bearing and legless segments (Fig. 5A, B, O, P); midbody segments showing all dorsal crests subdivided transversely (carinotaxy formulae 2/2+I/i+3/3+I/i+2/2) and sharper, especially so lateral crests (Fig. 5H, I).

Tegument delicately alveolate-areolate (Fig. 5A, B, H–J, M, O, P), dull throughout. Fine longitudinal striations in front of stricture between pro- and metazona, and remaining surface of prozona very delicately shagreened (Fig. 5J). Metatergal setae absent. Segments 2 and 3 with long pleural flaps. Limbus extremely finely and more or less regularly denticulate (Fig. 5K). Epiproct (Fig. 5O, P) simple, with an evident lateral tubercle placed level with ozoporiferous crests, also with a rounded ridge in caudal part and an evident axial rib dorsally. Paraprocts rather regularly convex, each with a faint premarginal sulcus medially (Fig. 5Q). Hypoproct bean-shaped, with 1+1 strongly separated setae near caudal margin (Fig. 5Q).

Ventral flaps behind gonopod aperture on ♂ segment 7 rather well distinguishable as low swellings forming a bare transverse ridge.

Legs rather short, on midbody segments about 3/4 length of segment height (Figs 5A, L, O, 7F). Claw at base with a strong accessory spine about 1/3–1/4 length of main claw. Tarsi and tarsal setae very delicately fringed (Fig. 7F).

♂ legs 1 highly characteristic (Figs 6A, 7C) in showing nearly fully developed, 4-segmented telopodites and a pair of large, subdigitiform, medially contiguous, but apically diverging coxal processes with a groups of long and strong setae at base.

♂ legs 2 nearly normal, only claw and, anteriorly, coxa somewhat reduced, and femur abbreviated on frontal face; penes broad, rounded, each with 4–5 strong setae distolaterally (Figs 6B, C, 7D).

♂ legs 3 modified in having coxa especially slender and elongate (Figs 6D, E, 7E).

Anterior gonopods (Figs 6F–J, 7G) with a typical shield-like coxosternum, this being rather densely microsetose on caudal face (Fig. 6G, I, J), with a high, digitiform, apicomesal process (d). Telopodite typical, slender, movable, 1-segmented, lateral in position, with 3–5 strong apical setae and a field of microsetae at base (Fig. 6H).

Posterior gonopods (Figs 6K–O, 7H, I) highly compact, both contiguous basally until about midheight; two densely and strongly setose lobes (l) paramedially (Fig. 6O); each half with two higher central pieces with a seminal groove between, frontal piece (a) elongate; long, distally microplumose flagella (f) (Fig. 6K–M); caudal piece (b) subquadrate, membranous, micropapillate frontolaterally, with an apical field of coniform microsetae laterally (Fig. 6L, N).

The javanicus-group is currently comprised of 23 species, including this new species, a fourth in this group to be reported from Laos.