Four new species of the Glyphiulus javanicus group from southern China (Diplopoda, Spirostreptida, Cambalopsidae)

Abstract Hitherto, 24 species of the Glyphiulus javanicus group have been recorded, all endemic to Southeast Asia, including 14 in China. Nevertheless, this species group needs further exploration. In this context, four new species of this group are described, all collected from limestone caves in Southern China: G. calceus sp. n., G. foetidus sp. n., G. guangnanensis sp. n., and G. impletus sp. n. They can be separated easily from each other and other congeners by their carinotaxic formulae, the structures of male legs I, and the gonopods. Due to the absence of any troglomorphic traits in our specimens, they may be troglophilic only.


Introduction
Since Golovatch et al. (2007b) established and revised the javanicus-group, one of two groups of the species-rich millipede genus Glyphiulus Gervais, 1847, 25 valid species have been recorded up to date. They are endemic to southeast Asia, distributed from tion, illustration, photography, and measuring using a Leica M205C stereomicroscope equipped with a Leica DFC450 Camera and LAS software (Version 4.1). Scanning electron micrographs (SEM) were taken with a Hitachi S-4800 field emission scanning electron microscope. Their geographical distributions were sketched with ArcGIS software (Ver. 10.2). All images were edited with Adobe Photoshop CC 2015 Software.
Terminology used in this paper follows the descriptions by Golovatch et al. (2007aGolovatch et al. ( , b, 2011 and Jiang et al. (2017). Collum. All crests on collum complete and fully developed, carinotaxic formula I-III + P + M ( Fig. 2A, B).
Male sexual characters. Male legs I strongly degenerated, with a pair of bi-segmented telopodites and a pair of large, subdigitiform, coxal processes. Coxal processes contiguous medially and curved forward, with clusters of long and robust setae at base (Fig. 3B). Male legs II normal. Penes trapeziform and small, each possessing three robust distolateral setae (Fig. 3C). Male legs III modified, with coxa especially slender and elongated (Fig. 3D). Femora VI and VII normal, not inflated.
Anterior gonopods. Coxosterna shield-like, sunken medially. Coxosternal mesal processes prolonged, obviously higher than telopodites. Telopodites one-segmented, Figure 2. Glyphiulus foetidus sp. n., holotype. A anterior part of body, dorsal view B same, lateral view C midbody segments, dorsal view D same, lateral view E posterior part of body, dorsal view F same, ventral view. placed laterally, curved and moveable, with several distal setae and a field of microsetae at base (Figs 4A, 5A, 6A).
Distribution. Known only from the type locality, a cave in Xilin County, Guangxi, and another cave in Guangnan County, Yunnan. The two caves are ca. 35 kilometres apart.    Etymology. This specific name is derived from the Latin word calceus, meaning 'shoe' and refers to the shape of the coxosternal mesal process of the anterior gonopod.
Diagnosis. The new species can be diagnosed by the following combination of morphological characteristics: (1) all crests on collum complete and fully developed, carinotaxic formula I-III + P + M; (2) telopodite of male legs I bi-segmented, obviously shorter than coxal process; (3) coxosternal mesal process of anterior gonopod prolonged and shoe-shaped; (4) flagellum of posterior gonopod short and zigzag-shaped. See also Key below.

Male sexual characters.
Telopodite of male legs I complete, five-segmented (Fig. 13B). Penes rather broad and round (Fig. 13C). Male legs II and III modified as usual (Fig. 13C, D). Femora VI and VII normal, not inflated.
Anterior gonopods. Coxosternum shield-like, sunken medially. Distal part of coxosternum with a deep indentation, the latter separating a mesal process and a lateral process. Coxosternal mesal process digitiform, obviously higher than telopodite. Coxosternal lateral process broad, with a blunt tip, nearly as high as telopodite. Telopodite short, onesegmented with thin and round tip and a field of microsetae at base (Figs 14A, 15A, 16A).
Distribution. Known only from the type locality, a cave in Guangnan County, Yunnan Province.
Notes. Since the definitions of Glyphiulus and Hypocambala are still uncertain, this new species may be a member of Hypocambala. Mauriès (1977) considered that the two genera are distinguished only by the absence (Hypocambala) and presence (Glyphiulus) of transverse crests on body. Golovatch et al. (2011) dealt with the crests as a species-level character, and transferred Glyphiulus vietnamicus Mauriès, 1977 to Hypocambala based on the complete male legs I. However, this arrangement didn't fully resolve this problem. In the genus Glyphiulus, there are still several species which present the same feature of male legs I and were not transferred to Hypocambala, for example G. costulifer, G. intermedius, G. parobliteratus, G. percostulifer, G. pulcher, and G. semicostulifer. A serious revision of the two genera is definitely needed but until then, this new species is assigned to Glyphiulus.
Usually, one cave supports one species of Cambalopsidae (Likhitrakarn et al. 2017). However, in our investigations, it was found that two species (G. guangnanensis sp. n. and G. foetidus sp. n.) could coexist in one place (Miaopu Cave), possibly due to the fact that they are troglophilic. Besides this, sympatry is also true for G. semigranulatus (likely troglophilic) and G. obliteratus (presumably troglobitic) which coexist in another cave (Bailong Cave).    Etymology. This specific name is derived from the Latin word impletus, meaning 'plentiful', referring to the large number of specimens of the new species in our collections.

Glyphiulus impletus
Diagnosis. The new species can be diagnosed by the following combination of morphological characteristics: (1) all crests on collum complete and fully developed, carinotaxic formula I-III + P + M; (2) telopodite of male leg I bi-segmented, shorter than coxal process; (3) coxosternal mesal process of anterior gonopod slender and strongly prolonged; (4) flagellum of posterior gonopod short and zigzag-shaped. See also Key below.
Distribution. Known from the type locality and several caves scattered in northwestern Guangxi.