Eutrichodesmus triangularis Golovatch, Geoffroy, Mauries & VandenSpiegel

Golovatch, Sergei I., Geoffroy, Jean-Jacques, Mauries, Jean-Paul & VandenSpiegel, Didier, 2015, Review of the millipede genus Eutrichodesmus Silvestri, 1910, in China, with descriptions of new cavernicolous species (Diplopoda, Polydesmida, Haplodesmidae), ZooKeys 505, pp. 1-34 : 2

Taxon classification Animalia Polydesmida Haplodesmidae

Eutrichodesmus triangularis Golovatch, Geoffroy, Mauries & VandenSpiegel sp. n. Figs 1, 2

Type material.

Holotype ♂ (MNHN JC 367), China, Sichuan Prov., Beichuan County, Cave Yan Dong, 18.VIII.2004, leg. J. Lips (No. 1583).

Name.

To emphasize the prominent, triangular, distofemoral process (dp) of the gonopod; adjective.

Diagnosis.

Differs from congeners by the prominent, triangular, distofemoral process of the gonopod (see also Key below).

Description.

Length ca 7.0 mm, width 0.9 and 1.5 mm on midbody pro- and metazonae, respectively. Coloration uniformly very light brown with pallid antennae, clypeolabral region, prozonae, venter, legs and metatergal tuberculations (Fig. 1).

Body with 19 segments (♂) (Fig. 1), conglobation pattern typical of “doratodesmoids”, volvation apparently being complete because of strongly declivous and relatively narrow paraterga. Tegument dull, meta- and paraterga with a cerategument layer. Antennae short and clavate. Head with a paramedian pair of small, but distinct, rounded tubercles above antennal sockets. Collum not covering the head from above, fore margin slightly elevated, with 4-5 transverse rows of flat tuberculations, first two and caudalmost rows being regular (Fig. 1). Metaterga behind collum with three transverse, rather irregular, mixostictic (= not regularly longitudinal) rows of similarly flat, rounded, obviously setigerous tuberculations extending onto paraterga, usually about 11-12+11-12 per row (Fig. 1); limbus microcrenulate. Paraterga with evident shoulders anteriorly, strongly declivous, directed ventrolaterad at about 45° to subvertical sides above paraterga, broad, tips about level with venter, distinctly trilobate laterally, without anterolaterals, but with 2-3 rounded caudolaterals (Fig. 1). Paraterga 2 rather strongly enlarged, directed ventrolaterad, lateral margin especially deeply trilobate, caudal margin with a row of lobules extending across dorsum, both schism and hyposchism small; paraterga 3 and 4 slightly shorter than others. Pore formula normal, ozopores indistinct, located dorsally between middle and caudolateral lobulations. Pleurotergal carinae wanting. Epiproct fully exposed in dorsal view, rather strongly flattened, dorsally also tuberculate, with several incisions at lateral edge, directed ventrocaudad, with the usual four cones just below tip (Fig. 1). Hypoproct subtrapeziform.

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 Eutrichodesmus asteroides Golovatch, Geoffroy, Mauriès & VandenSpiegel, 2009, from a cave in Vietnam ( Golovatch et al. 2009b).

More information on the location of the cave can be found at http://www.groupe-speleo-vulcain.com/explorations/expeditions-a-letranger/