Review of the millipede genusPlusioglyphiulusSilvestri, 1923, with descriptions of new species from southeast Asia (Diplopoda, Spirostreptida, Cambalopsidae)

Révision des diplopodes du genre Plusioglyphiulus Silvestri, 1923 et description de nouvelles espèces d’Asie du Sud-Est (Diplopoda, Spirostreptida, Cambalopsidae). Le genre Plusioglyphiulus Silvestri, 1923, fondamentalement réparti en Asie du Sud-Est, est redéfini afin d’incorporer, en plus des cinq espèces déjà connues, neuf nouveaux membres: P. ampullifer n. sp. du Vietnam, P. deharvengi n. sp., P. foveatus n. sp. et P. steineri n. sp. du Laos, P.bessoni n. sp. de Thaïlande, P.bedosae n. sp., P. pallidior n. sp. et P. similis n. sp. du Kalimantan (Bornéo, Indonésie), et P. hoffmani n. sp. du Sarawak (Bornéo, Malaisie).

Tous les congénères décrits ici sont cavernicoles mais sont supposés troglophiles. Une clé d’identification est donnée pour l’ensemble des 14 espèces maintenant connues de ce genre. INTRODUCTION The rather small, predominantly Southeast Asian genus Plusioglyphiulus Silvestri, 1923 was first proposed as a subgenus of Glyphiulus Gervais, 1847, to accommodate an aberrant cavernicolous species, Glyphiulus cavernicolus Silvestri, 1923, from Borneo (Silvestri 1923).

The subgenus was diagnosed by the presence of especially numerous carinae on the body segments, coupled with the peculiar conformation of male legs 1 and 2. Attems (1938), in his classification of Glyphiulus, abandoned Plusioglyphiulus, but added another species, G. dubius Attems, 1938, described from Cambodia, which he noted as being particularly similar to G. cavernicolus. Mauriès (1970) elevated Plusioglyphiulus to a full genus, to which he also transferred G. dubius and described a third congener, P. boutini Mauriès, 1970, from Cambodia.

Hoffman (1977) and Mauriès (1983) each provided a review of the genus and added two new species, P. grandicollis Hoffman, 1977, from Malaya, and P. macfarlanei Mauriès, 1983, from Borneo. Because a recent catalogue of the Cambalidea Bollman, 1893 is available (Jeekel2004) and is still entirely valid concerning Plusioglyphiulus the nomenclatural history of both the genus and of its constituent species can be briefly summarised as below in Systematics.

This genus has long been considered heterogeneous (Hoffman 1977; Mauriès 1983), chiefly because of the great variation observed in the gonopod structure of the few known constituent species. This is confirmed here by the new material reported below. However, we prefer to retain the genus Plusioglyphiulus for the above five species, as well as the nine new taxa described below, emphasizing instead that, at least for the time being, several natural species groups can be delineated.

Below, a description is given of the available new material, followed by a key to all the constituent species of Plusioglyphiulus, and brief analyses of their variation and distribution. ABBREVIATIONS MNHN Muséum national d’Histoire naturelle, Paris; MZB Museum Zoologicum Bogoriense, Cibinong, Indonesia; VMNH Virginia Museum of Natural History, Martinsville; ZMUC Zoological Museum, University of Copenhagen; ZMUM Zoological Museum, State University of Moscow; SEM scanning electron microscopy.

MATERIAL AND METHODS The material serving as the basis for the present contribution derives from the subterranean collections made in Vietnam, Laos and Indonesia by Anne Bedos and Louis Deharveng(MNHN),in Kalimantan, Indonesia by Yayuk Suhardjono and Cahyo Rahmadi (MZB), as well as from material taken in Laos (epigean) and Thailand (subterranean) by J.-P. Besson.Besides this, Richard L. Hoffman (VMNH) provided several cavernicolous samples from Laos and Malaysia.The bulk of the material has been deposited in MNHN, MZB and VMNH, with a few voucher specimens shared with the collections of ZMUM and ZMUC.

SEM micrographs were taken using a JEOL JSM-6480LV scanning electron microscope. Dried SEM material was coated with gold and, after study, removed from the stubs and returned to alcohol, all these samples being deposited in MNHN. The carinotaxy formulae in the descriptions below are those proposed by Hoffman (1977), with modifications.The carinotaxy formula of the collum designates the main, uninterrupted crests by Roman numerals; the nearly complete,only barely interrupted ones are also designated by Roman numerals, those frontally interrupted are marked “(a)”, those caudally interrupted are marked“(c)”.The strongly interrupted crests (with evident gaps) are designated by Arabic numerals, those frontally interrupted are marked “a”, while those caudally interrupted are marked “c”.

The paramedian and median crests are designated by upper case “P” or “M” and by lower case “p” or “m” when uninterrupted or interrupted, respectively. Intermediate tubercles or short crests are referred to as “(t)” without number, but with their respective row shown by a slash. The caudalmost row of short crests, which is very often regular and separated transversely from the anterior row(s), is shown as “//t” or “//(t)”.

All this allows not only the number but also the location and shape of the respective crest to be indicated (cf. Hoffman 1977). Slashes indicate the division of crests or tubercles into transverse rows.

Due to complete symmetry, only the formula corresponding to the left part of the collum is given (from laterad to mesad). Because variation in the formulae appears to be great, sometimes varying even intraspecifically, no typical arrangement and form of the crests on the collum seems to exist in this genus. However, Plusioglyphiulus species are generally characterised by a high number of collar crests and tubercles, of which at least 5 + 5 reach the anterior margin of the tergite.

In most of the species, several to all of the crests are subdivided into 2-4 parts, often with 1- 3 intercalary tubercles present in the posterior half of the collum (mixostichy, as opposed to isostichy, according to Hoffman [1977]). In contrast to Glyphiulus Gervais, 1847 (Golovatch et al. 2007a, b), the crests on the collum are always well developed, never being obliterated or reduced. The sole collar crest pattern that appears to be quite stable (though not without exceptions) can be reduced to pp/t/t+ma/t, the caudalmost row of short crests then being regular and set off by a distinct transverse sulcus from the crests or tubercles lying more anteriorly.

For a better understanding of the above explanations, the necessary designations are put on the respective crests or tubercles of the collum of P. grandicollis (Fig. 1B). This species is also chosen for one to be able to compare the more simple formula proposed by Hoffman (1977) and that, more elaborate but more exact, applied here. The carinotaxy pattern of metaterga first shows the number of crests below the ozoporiferous cone (designated as “I”), followed by that between the left and right “I”.

Slashes correspond to the division of crests or tubercles into transverse rows. Although the symmetry is also complete, when the formula is short, it is given for both sides of the body. When long, however, it again reflects only the left half of the segment.The typical carinotaxy formula of the midbody metaterga in this genus is as follows: 3(2)/3(2)+I/ i+3/3(4)/3+m/m+3/3(4)/3+I/i+3(2)/3(2), which is equivalent to 3(2)/3(2)+I/i+3/3(4)/3+m/m.This differs from the typical formulae of Glyphiulus species by an increased number of dorsal tubercles on the midbody metaterga (Golovatch et al. 2007a, b).

The body segment counts follow Enghoff et al. (1993), with minor modifications after Golovatch et al. (2007a, b). SYSTEMATICS Order SPIROSTREPTIDA Brandt, 1833 Suborder CAMBALIDEA Cook, 1895 Family CAMBALOPSIDAE Cook, 1895 Subfamily GLYPHIULINAE Chamberlin, 1922