Eutrichodesmus regularis 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 : 7-12

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

urn:lsid:zoobank.org:act:5137C5B6-4F58-4BCC-A746-21705E195066

Figs 4-7

Type material: Vietnam, Lao Cai Prov., Sa Pa, Hang Ta Phin Cave , hand collected, 11.VIII.2003, leg. L. Deharveng and Bedos (Vn0308-009), holotype ♁ (MNHN JC 318), paratypes: 1 ♁, 2 ♀, 1 subad., 1 juv. (MNHN JC 318), 1 ♀ (ZMUM), 1 ♁ (SEM) .

Name: To emphasize the highly regular, isostictic (i.e. regular rows not only transversely, but also longitudinally) and almost undifferentiated pattern of metatergal tuberculation.

Diagnosis: Differs from congeners by the perfect volvation, coupled with faint metatergal lobulations, the especially regular, nearly undifferentiated 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 9.0-10.0 mm, width 1.7-1.8 mm, 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 ).

Adults with 20 segments, pattern of conglobation typical of “doratodesmids” ( Figs 4 , 5A ). Head, antennae ( Fig. 5E ), tegument ( Figs 6 A-C), sterna ( Fig. 6E ), gonopod aperture ( Fig. 6F ) and many other characters ( Figs 5F , 6D ) much as in E. distinctus sp. n., but collum more regularly tuberculate and slightly flattened mid-dorsally ( Fig. 5B ). Metater- ga behind collum with three transverse, very regular and isostictic rows of subequallysized, rounded, flat, nearly undifferentiated tubercles ( Figs 5 A-D), each crowned with a short, 2-segmented, phylloid seta ( Fig. 6C ). Paraterga directed ventrolaterad, rather broad, slightly surpassing level of venter, slightly interrupting general outline of convex dorsum ( Figs 5A, C , 6D ); paraterga 2 strongly enlarged, each margin nearly entire, with only very faint traces of a series of small lobulations anterolaterally ( Figs 4 , 5A, B, D ). Following paraterga broadly rounded and slightly 3- or 4-lobate laterally and at least distinctly bilobate caudolaterally ( Figs 5A, C, D , 6F ). Limbus very faintly crenulate, almost hidden by nearby abundant microvilli ( Fig. 6A ). Pore formula normal, ozopores poorly visible, located dorsally near tip of ventrocaudal lobulation ( Figs 5C, D ).

Legs relatively long, slightly surpassing edge of paraterga ( Figs 6D, E ).

Gonopods ( Figs 6F, G , 7 A-E) relatively complex. Coxae subquadrate, large, microtuberculate, nearly bare, with only a few, mostly short setae on and near base of a small ventro-apical lobe. Telopodite considerably longer than coxite, slightly stouter and setose in its basal half, with an inconspicuous, digitiform, simple, lateral, distally papillate, distofemoral process (dp) at about midway, more distally with another simple outgrowth with its base marking recurvature point of a relatively short seminal groove; acropodite (= solenomere) relatively stout, lamelliform, slightly curved along main axis, with two small denticles apically and a conspicuous pilose-spinulate pulvillus near base ( Figs 7E, F ).

Remarks: This pallid species shows highly peculiar, phylloid but very short, tergal setae and undifferentiated metatergal tubercles. It is also a typical “doratodesmid”, possibly another troglobite.

Figures

Figure 4. Eutrichodesmus regularis sp. n., ♁ paratype; habitus, lateral view. (Photographed not to scale by L. Deharveng).

Figure 5. Eutrichodesmus regularis sp. n., ♁ paratype; A, habitus, lateral view; B, E, anterior part of body, frontodorsal and ventral views, respectively; C, midbody segments, dorsal view; D, F, posterior part of body, dorsal and ventral views, respectively. – Scale bars: A, C, 0.5 mm; B, D-F, 0.2 mm.

Figure 6. Eutrichodesmus regularis sp. n., ♁ paratype; A, texture of tegument, dorsal view; B, metatergal tubercle, dorsal view; C, metatergal seta, dorsal view; D, cross-section of a midbody segment, caudal view; E, midbody legs, caudal view; F, segments 7 and 8, ventral view; G, left gonopod in situ, caudoventral view. – Scale bars: A, B, 0.05 mm; C, 0.01 mm; D, F, 0.2 mm; E, G, 0.1 mm.

Figure 7. Eutrichodesmus regularis sp. n., ♁ paratypes; A-F, gonopods, frontoventral, submesal, mesal, mesal, mesal and lateral views, respectively. – Scale bars: A-C, 0.1 mm; D, 0.05 mm; E, F, 0.2 mm.