Eutrichodesmus distinctus Golovatch, Geoffroy, Mauriès & VandenSpiegel, 2009

Golovatch, Sergei, Geoffroy, Jean-Jacques, Mauriès, Jean-Paul & VandenSpiegel, Didier, 2009, Review of the millipede genus Eutrichodesmus Silvestri, 1910 (Diplopoda, Polydesmida, Haplodesmidae), with descriptions of new species, ZooKeys 12 (12), pp. 1-46 : 3-7

Eutrichodesmus distinctus Golovatch, Geoffroy, Mauriès & VandenSpiegel , sp. n.

urn:lsid:zoobank.org:act:5E777CD8-34D0-4820-9D76-0017195D53AD

Figs 1-3

Type material: China, Guangxi Prov., Fushui, Bapen, Cave 4, 4.III.2005, leg. L. Deharveng and A. Bedos (CHIgx05-035), holotype ♁ (SCAU), paratypes: 1 ♀ (SCAU), 1 ♁ (MNHN JC 317), 1 ♁ (ZMUM), 1 ♁ (SEM) .

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: Differs 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 1.35–1.40 mm, 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 ).

Adults with 20 segments, body subcylindrical ( Figs 1 , 2A), conglobation complete, pattern of volvation typical, starting from segment 5 (cf. Golovatch 2003) ( Fig. 2B ). Head ( Fig. 3C ) slightly transverse (wider than high), rather densely pilose, microgranular and microvillose just below antennae and on vertex, with a pair of rounded,

paramedian knobs; isthmus between antennal sockets about as wide as diameter of antennal socket. Antennae ( Fig. 3C ) rather long and slender; antennomere 6 longer than 5, both with an evident dorso-apical pit containing a tight group of minute bacilliform sensilla; antennomere 8 with the usual four sensory cones apically. Collum rather large, broader than head, distinctly flattened medially near front margin, not covering the head from above; entire surface microvillose, with several transverse rows of round tubercles ( Fig. 2E ). Prozona very finely alveolate, collum and metaterga covered with a cerotegumental crust held by abundant microvilli; stricture between pro- and meta- zona broad and shallow, more finely alveolate-microgranular than prozona. Limbus microcrenulate, partly hidden by nearby abundant microvilli ( Fig. 3D ). Metaterga behind collum with three transverse and mixostictic (i.e. irregular in axial direction) rows of tubercles, second row being highest and best expressed in posterior part of body ( Figs 1 , 2A-G). Paraterga strongly declivous, rather broad and trilobate laterally, evidently surpassing level of venter, caudolaterally at base with 1-2 distinct lobulations ( Figs 2 A-G, 3A); middle and, especially, posterior parts of body set off laterally at base by a distinct impression, thus somewhat interrupting contour of convex dorsum; paraterga 2 strongly enlarged, with a series of lobulations anterolaterally, schism and hyposchism both very small; paraterga 3 and 4 slightly shorter than others ( Fig. 2B ), overlap of following paraterga typical. Pore formula normal (5, 7, 9, 10, 12, 13, 15- 19), ozopores very indistinct, located near top of caudolateral lobulation. Metatergal setation wanting. Pleurotergal ridges absent. Epiproct short, also with differentiated tubercles, directed ventrocaudad, with the usual four cones just below tip. Hypoproct and paraprocts normal ( Fig. 3B ).

Sterna usually with a deep, narrow, transverse depression between coxae ( Fig. 3A ), only sterna between ♁ coxae 6, 7 and 9 much wider. Gonopod aperture suboval, relatively small, far from reaching lateral sides of segment 7 ( Fig. 3E ). Legs rather long and relatively slender, barely reaching tips of paraterga; femoral and tarsal segments longest, subequal in length; claw normal, simple, very slightly curved ventrad; some setae with microdenticulations ( Fig. 3A ).

Gonopods ( Figs 3 F-H) very simple. Coxae subquadrate, large, microtuberculate and abundantly setose ventrolaterally, with a conspicuous triangular lobe frontolaterally. Telopodite longer than coxite, slender throughout, setose in its basal half, with a conspicuous, denticulate, lateral, distofemoral process (dp) at about midway, seminal groove terminating subapically near a small spiniform prong.

Remarks: This pallid species shows differentiation of the metatergal tubercles in the second row growing steadily higher towards the telson, coupled with the absence of tergal setation. It is a typical “doratodesmid” (capable of volvation, see Golovatch et al. 2009), possibly a troglobite.

Figures

Figure 1. Eutrichodesmus distinctus sp. n., ♁ paratype; habitus, lateral view. (Photographed not to scale by L. Deharveng).

Figure 2. Eutrichodesmus distinctus sp. n., ♁ paratype; A, habitus, lateral view; B, E, anterior part of body, lateral and dorsal views, respectively; C, F, midbody segments, lateral and dorsal views, respectively; D, G, posterior part of body, lateral and dorsal views, respectively. – Scale bars: A, 0.5 mm; B-G, 0.2 mm.

Figure 3. Eutrichodesmus distinctus sp. n., ♁ paratypes; A, midbody segments, ventral view; B, telson, ventral view; C, anterior part of body, ventral view; D, texture of tegument, dorsal view; E, both gonopods in situ, ventral view; F-H, gonopod, ventral, mesal and lateral views, respectively. – Scale bars: A, 0.5 mm; B, E, G, 0.1 mm; C, H, 0.2 mm; D, 0.02 mm; F, 0.05 mm.

Figure 10. Eutrichodesmus aster sp. n., subadult paratype from Tham Han Cave; A, E, midbody segments, dorsal and ventral views, respectively; B, C, posterior part of body, dorsal and caudal views, respectively; D, anterior part of body, ventral view; F, cross-section of a midbody segment, caudal view; G, texture of tegument, dorsal view. – Scale bars: A, B, F, 0.5 mm; C-E, 0.2 mm; G, 0.05 mm.