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

Abstract The Eutrichodesmus fauna of mainland China, by far the largest genus in the Indo-Australian family Haplodesmidae, is reviewed and shown to encompass 23 species (of a total of 45), all keyed. The following nine new species, all presumed troglobites, are described: Eutrichodesmus triangularis sp. n., from Sichuan, Eutrichodesmus lipsae sp. n., from Guangxi, Eutrichodesmus tenuis sp. n., Eutrichodesmus trontelji sp. n., Eutrichodesmus latellai sp. n., Eutrichodesmus obliteratus sp. n. and Eutrichodesmus troglobius sp. n., all from Guizhou, Eutrichodesmus sketi sp. n., from Hunan, and Eutrichodesmus apicalis sp. n., from Hubei.

Sterna usually with a deep and narrow depression between coxae. Legs short, crassate except for slender tarsi, about as long as body height. Gonopods (Fig. 2) simple. Coxae subquadrate, large, microtuberculate and abundantly setose ventrolaterally, with a conspicuous round lobe caudolaterally. Telopodite considerably longer than coxite, but not too slender, subfalcate, distinctly curved ventrad, setose not only in its basal half, including mesal face at base of a prominent, triangular, acuminate, distofemoral process (dp), the latter situated at about midway along telopodite, more distally with a lobe-shaped, rounded, distad slightly enlarged acropodite showing a short, distoventral, subapical spine (s); seminal groove terminating subapically, devoid of a hairpad.
Remarks. The presence of only 19 body segments is rare in Eutrichodesmus, but generally quite common in Haplodesmidae (Golovatch et al. 2009a). Among congeners, the above new species seems to share this feature only with E. asteroides Golovatch, Geoffroy, Mauriès & VandenSpiegel, 2009, from a cave in Vietnam (Golovatch et al. 2009b).
Sterna usually with a rather deep, narrow depression between coxae (Fig. 3I, J). Legs long and slender, about 1.1-1.2 times as long as body height.
Remark. More information on the location of the cave can be found at http:// www.groupe-speleo-vulcain.com/explorations/expeditions-a-letranger/ Name. To emphasize the relatively slender body due to subvertical paraterga; adjective. Diagnosis. Differs from congeners by the large body size, clearly elevated middorsal regions of most metaterga, coupled with narrow, strongly declivous, subvertical paraterga and a simple, falcate gonopod telopodite carrying a long, spiniform, distofemoral process (see also Key below).
Remark. More information on this cave and its fauna can be found in Latella and Hu (2008) and in Latella and Zorzin (2008). Name. In honour of Peter Trontelj, the collector. Diagnosis. Differs from congeners by the particularly broad and moderately declivous paraterga which are set at about 45° to the vertical axis and continue the outline of the sides above paraterga, coupled with mostly 4-5 irregular rows of flat setigerous tubercles/bosses per metatergum, the calyx-shaped tergal setae, and the fairly complex gonopod (see also Key below).

Eutrichodesmus trontelji
Description. Length of adults ca 8-9 mm, width 1.2 and 2.2 mm (♂ paratype and one ♀ non-type from Shui Jiang Dong) to 1.5 and 2.5 mm (♂ holotype and other non-types) on midbody pro-and metazonae, respectively. Coloration entirely pallid, except some traces of reddish earth material on paraterga.
Remarks. The conspecificity of the non-type samples with E. trontelji sp. n. is documented in Figs 9-11. It is also corroborated by provenance from the same karst in Libo County, Guizhou Province. Small variations seem to only concern gonopod structure, i.e. the presence in the gonopods of the types of a small tooth k and the absence of a tooth j. Interestingly, calyx-shaped tergal setae among Eutrichodesmus are also observed only in two cavernicolous species from Guangxi: E. latus and E. similis (see Golovatch et al. 2009a). Name. In honour of Leonardo Latella, one of the main collectors. Diagnosis. Differs from congeners by the broad and moderately declivous paraterga which are set at about 45° to the vertical axis and almost continue the outline of the sides above paraterga, coupled with three irregular rows of flat setigerous bosses per metatergum, and the especially simple gonopod (see also Key below).
Remark. More information on this cave and its fauna can be found in Latella and Hu (2008) and in Latella and Zorzin (2008).  Diagnosis. Differs from congeners by the largely obliterate metatergal tuberculation (even those at the fore margin of metetergum 2), the rather broad and strongly declivous paraterga which are set at about 30° to the vertical axis and continue the outline of the sides above paraterga, coupled with three irregular rows of very flat setigerous bosses per metatergum, and the fairly complex gonopod telopodite (see also Key below).
Sterna usually with a rather deep, narrow depression between coxae (Fig. 14G-I). Legs long and slender, about as long as body height (Figs 14G-J, 15A), only coxae and most surface of prefemora finely micropapillate (Fig. 15A).
Remark. More information on this cave and its fauna can be found in Latella and Hu (2008) and in Latella and Zorzin (2008). Paratype: 1 subadult ♀ (SEM), same data, together with holotype. Name. In honour of Boris Sket, one of the main collectors. Diagnosis. Differs from congeners by the relatively narrow and strongly declivous paraterga which are set low on the body at about 30° to the vertical axis and nearly continue the outline of the sides above paraterga, the low, but distinct, rounded, metatergal bosses arranged in three transverse irregular rows, and the rather simple gonopod (see also Key below).
Sterna usually with a rather deep, narrow depression between coxae (Fig. 16G-I). Legs long and slender, about as long as body height (Fig. 16F, G), only coxae and most surface of prefemora finely micropapillate (Fig. 17A).

Eutrichodesmus apicalis
Remark. More information on the location of the cave can be found at http:// www.groupe-speleo-vulcain.com/explorations/expeditions-a-letranger/ Name. To emphasize cavernicoly; adjective. Diagnosis. Differs from congeners by the relatively broad and modestly declivous paraterga which are set low on the body at about 45° to the vertical axis and distinctly discontinue the more strongly declined outline of the sides above paraterga, coupled with low, but distinct, mostly longitudinally oblong, metatergal tuberculations arranged in three transverse irregular rows, and the rather simple gonopod acropodite which only shows a small distodorsal tooth (see also Key below). Description. Length of adults ca 8-9 mm, width 1.0 and 1.9-2.0 mm on midbody pro-and metazonae, respectively. Holotype ca 9 mm long, 1.0 and 2.0 mm wide on pro-and metazonae, respectiverly. Coloration entirely pallid.

Conclusion
The nine new species described here are presumed to be troglobites, as all were collected in caves and all are troglomorphic in unpigmented teguments. Their discovery supports the ideas that Eutrichodesmus is one of the most speciose millipede genera in China, that the true cavernicoles among Eutrichodesmus species are mainly confined to southern China's karsts, and that many more Chinese Eutrichodesmus species are yet to be collected and described. Adult body with 19 segments (Fig. 1). Distofemoral process (dp) of gonopod triangular and acuminate (Fig. 2)  Mid-dorsal regions of metaterga increasingly strongly elevated towards segment 17 due to enlarged tubercles of middle row, thereafter smaller ( Fig. 3A-H). Gonopod distofemoral process (dp) held subparallel to acropodite (Figs 3N-Q, 4) Each postcollum metatergum with 4-5 irregular rows of bosses (Figs 7A-G, 9A-F, 11A-G). Gonopod distofemoral process (dp) long and microtuberculate, acropodite with a mesal fold (fd), the latter sometimes extended into an apical tooth (j) (Figs 8B, C, 10