Glyphiulus semicostulifer Likhitrakarn, Golovatch & Panha

Likhitrakarn, Natdanai, Golovatch, Sergei I., Inkhavilay, Khamla, Sutcharit, Chirasak, Srisonchai, Ruttapon & Panha, Somsak, 2017, Two new species of the millipede genus Glyphiulus Gervais, 1847 from Laos (Diplopoda, Spirostreptida, Cambalopsidae), ZooKeys 722, pp. 1-18 : 4-9

Glyphiulus semicostulifer Likhitrakarn, Golovatch & Panha sp. n. Figs 1C, D, 5, 6, 7

Type material.

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.

Etymology.

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

Diagnosis.

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.

Description.

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, 5 A–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 8th to 10th)> 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. 5 A–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, 5 A–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 6 F–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 6 K–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. 6 K–M); caudal piece (b) subquadrate, membranous, micropapillate frontolaterally, with an apical field of coniform microsetae laterally (Fig. 6L, N).

Remark.

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