Review of the millipede genus Eutrichodesmus Silvestri , 1910 ( Diplopoda , Polydesmida , Haplodesmidae ) , with descriptions of new species

Eutrichodesmus, the largest genus in the Oriental family Haplodesmidae, is reviewed and shown to encompass 24 recognizable species, all keyed, including the following nine new species: E. regularis sp. n., E. aster sp. n., E. fi lisetiger sp. n., E. curticornis sp. n., E. asteroides sp. n. and E. griseus sp. n. from Vietnam, E. distinctus sp. n. from China, E. multilobatus sp. n. from Laos, and E. reductus sp. n. from Sulawesi, Indonesia. Th is genus is slightly redefi ned as follows: Gonopod coxae usually abundantly setose ventrolaterally; telopodite usually slender, not enlarged towards end of femorite, but typically with a more or less distinct process or outgrowth laterally, opposite recurvature point of seminal groove; solenomere thereafter usually comprising most of telopodite, sometimes elaborate; seminal groove normally terminating distally to subapically, with or without a hairpad; acropodite normally small to nearly absent. ZooKeys 12: 1-46 (2009) doi: 10.3897/zookeys.12.167 www.pensoftonline.net/zookeys Copyright Sergei I. Golovatch et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Launched to accelerate biodiversity research A peer-reviewed open-access journal


Introduction
Th e millipede family Haplodesmidae Cook, 1895, which has only six component genera basically occurring (except for a few pantropical introductions) in East and Southeast Asia, as well as the southwestern Pacifi c region, has recently been reviewed (Golovatch et al. 2009).
Th e present paper records another nine new species of Eutrichodesmus, thus improving our knowledge of the diversity of this Oriental genus.Th e descriptions below are arranged by countries in a more or less north-south direction.

Material and methods
Th e material serving as the basis for the present contribution derives mainly from subterranean collections made in Vietnam, China, Laos, and Indonesia by Anne Bedos and Louis Deharveng (MNHN).Th e bulk of this material, including most of the holotypes, has been deposited in MNHN, with two holotypes and a few paratypes from China and Indonesia shared between the collections of SCAU and MZB, respectively, and some further paratypes deposited in the collection of ZMUM, as indicated hereafter.Th e terms "doratodesmid" or "haplodesmid" are used hereafter only in their vernacular meaning, in order to concisely characterize a body shape, i.e. capable or nearly capable of volvation in the former informal group versus vermiform and definitely incapable of valvation in the latter.
SEM micrographs were taken using a JEOL JSM-6480LV scanning electron microscope.After examination, SEM material was removed from stubs and returned to alcohol, all such samples being kept at MNHN.
Name: To emphasize the obvious distinctions from E. latus and E. similis, these being the only congeners hitherto known from Guangxi Province (Golovatch et al. 2009).
Diagnosis: Diff ers from all other congeners in the especially distinct metatergal tuberculation, coupled with the lack of tergal trichome, as well as only a few minor details of gonopod structure (in particular, the shape of the telopodite).In addition, it can be separated from the other species known from the same province, E. latus and E. similis, by the apparently perfect volvation (due to much shorter and more strongly declivous paraterga).
Description: Length of adults of both sexes ca 8.0-8.5 mm, width 1.35-1.40mm, body broadest at segment 3 or 4. Holotype ca 8.0 mm long and 1.4 mm wide.Coloration uniformly pallid, shown pinkish because of a photographic artifact (Fig. 1).

Eutrichodesmus regularis
Name: To emphasize the highly regular, isostictic (i.e.regular rows not only transversely, but also longitudinally) and almost undiff erentiated pattern of metatergal tuberculation.
Diagnosis: Diff ers from congeners by the perfect volvation, coupled with faint metatergal lobulations, the especially regular, nearly undiff erentiated and isostictic pattern of metatergal tuberculation, the peculiar, phylloid tergal setae and a few minor details of gonopod structure (in particular, the shape of the telopodite and distofemoral process).
Description: Length of adults of both sexes ca 9.0-10.0mm, width 1.7-1.8mm, body broadest at segment 3 or 4. Holotype ca 10 mm long and 1.7 mm wide.Coloration uniformly pallid, shown pinkish because of a photographic artifact (Fig. 4).
Remarks: Th is pallid species shows highly peculiar, phylloid but very short, tergal setae and undiff erentiated metatergal tubercles.It is also a typical "doratodesmid", possibly another troglobite.Diagnosis: Diff ers from all congeners, except E. macclurei and E. reclinatus, by the extremely high mid-dorsal crests on metaterga 5-19.In addition, it can be distinguished from E. macclurei and E. reclinatus in the presence of a mid-dorsal projection on metatergum 4, the slightly more strongly declivous and quadrilobate paraterga.Th e new species diff ers from all other species of the genus in minor details of gonopod structure (in particular, the shape of the telopodite and distofemoral process).Description: Length of adults of both sexes ca 12-14 mm, width 2.1-2.3 mm, body broadest at segment 3 or 4. Holotype ca 12 mm long and 2.2 mm wide.Coloration uniformly pallid, shown pinkish because of a photographic artifact (Fig. 8).
Remarks: Th is pallid species shows peculiarly high mid-dorsal projections, coupled with short, distally fl attened tergal setae.It is also a typical "doratodesmid", possibly another troglobite.Name: To emphasize the peculiar, fi liform but rather short tergal setae.

Eutrichodesmus fi lisetiger
Diagnosis: Diff ers from congeners by the perfect volvation, coupled with the fi liform tergal setae, evident metatergal lobulations, a regular pattern of tergal tuberculation and a few minor details of gonopod structure (in particular, the shape of the telopodite and a rudimentary distofemoral process).
Description: Length of adults of both sexes ca 12-13 mm, width 2.5-2.6 mm, body broadest at segment 3 or 4. Holotype ca 12 mm long and 2.5 mm wide.Coloration uniformly pallid, shown pinkish because of a photographic artifact (Fig. 12).
Remarks: Th is rather large, pallid species shows fi liform tergal setae and only poorly diff erentiated metatergal tubercles.It is also a typical "doratodesmid", possibly still another troglobite.Name: To emphasize the unusually short antennae.Diagnosis: Diff ers from congeners by the perfect volvation, coupled with the very short antennae, legs and paraterga, the contiguous paramedian tubercles above the antennal sockets, the regular mixostictic pattern of metatergal tuberculation and a few minor details of gonopod structure (in particular, the shape of the telopodite and distofemoral process).
Legs very short and stout, barely reaching edge of paraterga (Fig. 18F).Gonopods (Figs 18G, H) relatively complex.Coxae abundantly micropapillate and setose, with a usual, apicolateral lobe.Telopodite elongate, slender, only very slightly arcuate, with a marked, denticulate distofemoral process (dp) at about midway and an evident distolateral tooth; seminal groove terminating without hairpad at base of the tooth.
Remarks: Th is pallid species shows short antennae, legs and paraterga, all these traits apparently being related to the small body size.It is also a typical "doratodesmid", possibly yet one more troglobite.Name: To emphasize the nearly star-shaped but broad body of the volvated animal.

Eutrichodesmus asteroides
Diagnosis: Diff ers from congeners by the peculiar, subtriangular, rather high, mid-dorsal crests on metaterga 4-18, coupled with 19 body segments, the relatively wide paraterga and a few minor details of gonopod structure (in particular, the shape of the telopodite and a rudimentary distofemoral process).
Description: Length of adults of both sexes ca 8.0-8.5 mm, width 2.1-2.5 mm, body broadest at segment 3 or 4. Holotype ca 8.0 mm long and 1.9 mm wide.Coloration uniformly pallid, shown pinkish because of a photographic artifact (Fig. 19).
Diagnosis: Diff ers from congeners by the peculiar, grey to blackish coloration, coupled with the relatively short and high paraterga (thus the body apparently not capable of complete volvation) and a few minor details of gonopod structure (in particular, the shape of the telopodite and distofemoral process).Description: Length of adults of both sexes ca 6.0-6.5 mm, width 0.7-0.75mm, body broadest at segment 3 or 4. Holotype ca 4.5 mm long and 2.5 mm wide.Coloration of vertex, collum, following metaterga, and of dorsal and lateral parts of telson greyish to dark grey.Clypeolabral part of head, venter and legs contrastingly pallid (Fig. 23).Holotype light grey.
Legs relatively short and stout, barely reaching edge of paraterga (Figs 25C-E).
Remarks: Because this pigmented species obviously shows incomplete volvation, it is not a typical "doratodesmid", defi nitely epigean.Moreover, because of the elevated anterior row of tubercles on the collum, superfi cially it slightly resembles certain Pyrgodesmidae.Name: To emphasize the mostly 5-lobulated paraterga.

Eutrichodesmus multilobatus
Diagnosis: Diff ers from congeners by the peculiar, evidently and only laterally 5-lobulated paraterga, coupled with very distinct but only slightly diff erentiated metatergal tuberculation and a few minor details of gonopod structure (in particular, the shape of the telopodite and distofemoral process).
Description: Length of adults of both sexes ca 6.0-6.5 mm, width 1.1-1.2mm, body broadest at segment 3 or 4. Holotype ca 6.0 mm long and 1.1 mm wide.Coloration uniformly pallid, shown pinkish because of a photographic artifact (Fig. 27).
Name: To emphasize the strongly underdeveloped paraterga 2 and lack of metatergal tuberculation.
Diagnosis: Diff ers from congeners except E. communicans Golovatch, Geoff roy, Mauriès & VandenSpiegel, 2009 by the strongly underdeveloped paraterga 2, coupled with 19 body segments and the absence of metatergal tuberculation; from E. communicans by a very short tergal trichome, from it and other congeners in a few minor details of gonopod structure (in particular, the shape of the telopodite).Description: Length of adults of both sexes ca 4.0-4.2mm, width 0.45-0.5 mm, body broadest at midbody segments.Holotype ca 4.0 mm long and 0.45 mm wide.Coloration uniformly pallid, shown pinkish because of a photographic artifact (Fig. 31).
Legs relatively long and slender, evidently surpassing edge of paraterga (Fig. 33B).Gonopods (Fig. 33F, G) relatively complex.Coxae abundantly micropapillate, but only with a few macrosetae.Telopodite elongate, only slightly arcuate, with a large, papillate, peculiar, distofemoral outgrowth (dp) in distal one-third and a slender but short solenomere bearing a few small setae (but no pad!) subapically at base of a very

Discussion
Now that Eutrichodesmus has grown even more speciose, containing 24 species and no doubt with more still remaining to be discovered, it seems appropriate to redefi ne it and provide an updated key.Th e defi nition of the genus (cf.Golovatch et al. 2009) is therefore amended as follows: Eutrichodesmus Silvestri, 1910 Type-species: Eutrichodesmus demangei Silvestri, 1910, by original designation.

New diagnosis
Body usually "doratodesmid", with or without mid-dorsal projections; conglobation usually complete, only seldom imperfect due to underdeveloped or hypertrophied paraterga.Collum and metaterga often (micro)setose, usually tuberculate, only rarely smooth.Gonopod coxae usually abundantly setose ventrolaterally; telopodite usually slender, not enlarged towards end of femorite, but typically with a more or less distinct process or outgrowth laterally, opposite recurvature point of seminal groove; solenomere thereafter usually comprising most of telopodite, sometimes elaborate; seminal groove normally terminating distally to subapically, with or without a hairpad; acropodite normally small to nearly absent.

Conclusion
As stated recently (Golovatch et al. 2009), there seem to be almost no coherent patterns in the distribution of the various non-genitalic and gonopodal characters in Eutrichodesmus.Th e same concerns geographic patterns.Only a few pairs of particularly similar species can be distinguished in this speciose genus: e.g.E. macclurei and E. reclinatus, E. latus and E. similis, E. demangei and E. arcicollaris, and E. communicans and E. reductus sp.n.However, it is still too early to attempt to discriminate species groups, because many more new species of Eutrichodesmus can be expected to occur at least in East and Southeast Asia, as well as in the Indo-Australian archipelago, which seem to represent the centre of diversity of this genus (Fig. 34), and of the entire family Haplodesmidae.
Th at most of the Eutrichodesmus species have been found and described from cave material alone does not necessarily mean their obligate cavernicoly, even though many of them exhibit troglomorphic features.Most of the caves are simply better explored than the adjacent, much less prospected, epigean habitats.