Two new species of the millipede genus Glyphiulus Gervais, 1847 from Laos (Diplopoda, Spirostreptida, Cambalopsidae)

Abstract Two new species of Glyphiulus are described and illustrated from northern Laos. The epigean Glyphiulus subbedosae Likhitrakarn, Golovatch & Panha, sp. n. is the second member of the granulatus-group to be found in that country and it seems to be especially similar to G. bedosae Golovatch, Geoffroy, Mauriès & VandenSpiegel, 2007. However, it differs from the latter species by 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, but larger lateral teeth on the coxosternal plate. Glyphiulus semicostulifer Likhitrakarn, Golovatch & Panha, sp. n. is the fourth member of the javanicus-group to be discovered in Laos, taken from a cave. It seems to be particularly similar to G. costulifer Golovatch, Geoffroy, Mauriès & VandenSpiegel, 2007, but is distinguished by the more sparsely alveolate background fine structure of the metazonae, coupled with the gnathochilarium being considerably less densely setose on the caudal face, much stronger paramedian prongs and 4-segmented telopodites on ♂ coxae 1, the slightly longer and more slender apicoparamedian sternal projections on the anterior gonopods, and the much longer flagella of the posterior gonopods. An identification key to and a distribution map of Glyphiulus species in Laos are also presented.


Introduction
The large southeast Asian millipede genus Glyphiulus Gervais, 1847 has recently been reviewed and shown to comprise 57 species ranging from southern China, northern Laos, and northern Thailand in the north to southern Vietnam in the south (Golovatch et al. 2007a, b;2011a, b;Jiang et al. 2017). Only one species, G. granulatus (Gervais, 1847), has attained a pantropical distribution due to numerous anthropochore introductions. Golovatch et al. (2007a, b) divide this genus into two species groups, based on the conformation of ♂ legs 1. The granulatus-group is distinguished by these legs being devoid of median structures, but supplied instead with two widely separated prongs, coupled with often 1-or 2-segmented telopodites. In contrast, the javanicusgroup shows ♂ legs 1 provided with medially contiguous, but not entirely fused coxal processes, coupled with usually 4-or 5-segmented telopodites, along with special carinotaxy patterns of the collum and following metaterga.
The Lao People's Democratic Republic still supports some of the most significant forested areas remaining anywhere in southeast Asia, especially in the mountains in the north and limestone karsts in central parts (Kemp 2011). A distinctive geological feature of the numerous karst landscapes of the country is a multitude of complex cave systems. Such pronounced habitat diversity is also reflected in millipede faunal richness, the diplopod list of Laos being estimated to amount to at least 130 species (Likhitrakarn et al. 2014a).
The present paper is devoted to descriptions of two new species of Glyphiulus from Laos, coupled with a distributional map of and a key to all six species of the genus currently known to occur in that country.

Materials and methods
New material was collected from northern Laos in 2014 by SP and members of the Animal Systematics Research Unit, Chulalongkorn University. Photographs of live animals were taken in the laboratory using a Nikon 700D digital camera with a Nikon AF-S VR 105mm macro lens. Specimens were preserved in 75% ethanol, and morphological observations made under an Olympus SZX7stereo microscope.
Scanning electron micrographs (SEM) were taken with a JEOL, JSM-5410 LV microscope, and the material returned to alcohol upon examination. Pictures of one of the gonopods of the holotypes were taken in the laboratory and assembled using the "Cell D " automontage software of the Olympus Soft Imaging Solution GmbH package. The key to all species is principally based on the descriptions by Golovatch et al. (2007aGolovatch et al. ( , 2007bGolovatch et al. ( , 2010Golovatch et al. ( , 2011aGolovatch et al. ( , 2011b. The holotypes, as well as most of the paratypes are housed in the Museum of Zoology, Chulalongkorn University (CUMZ), Bangkok, Thailand; paratypes have been donated to the collection of the Zoological Museum, State University of Moscow, Russia (ZMUM), as indicated in the text.
The collecting sites were located by GPS using the WGS84 datum. The carinotaxy formulae in the descriptions follow those in Golovatch et al. (2007aGolovatch et al. ( , 2007b, while body segment counts are after Enghoff et al. (1993). Diagnosis. 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.
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.
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).
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.
Remarks. 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. 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.
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.
Ventral flaps behind gonopod aperture on ♂ segment 7 rather well distinguishable as low swellings forming a bare transverse ridge.
♂ 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.
Remark. The javanicus-group is currently comprised of 23 species, including this new species, a fourth in this group to be reported from Laos. Paraprocts with a row of several strong setae near median marginal ridge (Fig. 2Q); posterior gonopods broadly subquadrate, each half with a plumose apical flagellum (f ) (Fig. 3I, J)