Eutrichodesmus parvus Liu & Wesener

Liu, Weixin, Golovatch, Sergei & Wesener, Thomas, 2017, Four new species of the millipede genus Eutrichodesmus Silvestri, 1910 from Laos, including two with reduced ozopores (Diplopoda, Polydesmida, Haplodesmidae), ZooKeys 660, pp. 43-65 : 50-54

Eutrichodesmus parvus Liu & Wesener sp. n. Figs 1D, 11, 12, 13

Material examined.

Holotype male (SMF), Laos, Huaphan Prov., Cave Tham Nam Long (F 48-125-007), N 20°27'50.3", E 104°9'10.7", 10.I.2008, coll. H. Steiner (133/08-).

Paratypes.

1 male (SEM), (ZFMK MYR6132), 1 female (ZFMK MYR6128), same data as holotype; 2 females (SMF), same data.

Etymology.

To emphasize the very small body of this species; adjective.

Diagnosis.

Differs from other species of the genus in the very small body (4.0-5.0 mm long), three regular transverse rows of round microvillose tubercles on metaterga, short paraterga, as well as the relatively complex gonopod with a large, laterally denticulate, distofemoral process; the acropodite subapically has a small dorsal tooth and an evident, digitiform, ventral lobe; the seminal groove is devoid of a hairpad near the place of its termination. See also Key above.

Description.

Length of adults of both sexes ca.4.0-5.0 mm, width 0.3-0.4 mm and 0.6-0.8 mm on midbody pro- and metazona, respectively.

Coloration uniformly light yellow-brown with pallid antennae (Fig. 1D).

Adults with 20 segments (Fig. 1D), body subcylindrical, conglobation incomplete.

Antennae short (Fig. 1D); in length, antennomere 6> 5> 2> 3 = 4> 7> 1.

Labrum with three teeth (Fig. 11A).

Head (Fig. 11A), bacilliform sensilla of antenna (Fig. 12C), gnathochilarium (Fig. 12A), mandible (Fig. 12B), prozona (Fig. 11G), endoterga (Fig. 12F), sterna, pleurosternal keels, gonopod aperture (Fig. 11F), telson (Fig. 11 C–D) and vulvae all similar to those in Eutrichodesmus steineri sp. n.

Collum semi-circular, with five transverse rows of round, small, microvillose tubercles (Fig. 11E). First row with 12 round tubercles (Fig. 11E).

Stricture between pro- and metazona broad and shallow, more finely alveolate-microgranular than prozona (Fig. 11G). Limbus regularly microcrenulate (Fig. 12E).

Metaterga 2 to pre-anal segment each with three transverse rows of high, round, regular, microvillose tubercles, usually about 5 + 5 per row (Figs 11-12). Metatergal setae inconspicuous, mostly abraded.

Paraterga short, slightly extending down below level of venter, especially paraterga 18 and 19 being shorter with previous one (Figs 11J, 12H); usually trilobate laterally and with two caudal lobulations (Figs 11F, I, J, 12H).

Pore formula normal, ozopores distinct, located near top of caudolateral lobulation (Fig. 12 G–H).

Legs long and slender, femur somewhat longer than tarsus (Fig. 12I).

Gonopods (Figs 12 J–K, 13) relatively complex. Coxae large, micropapillate and setose ventrolaterally, with a large apicolateral lobe (cl). Telopodite slightly longer than coxite, slender throughout, setose in basal half, with a large, prominent, denticulate, lateral, distofemoral process (dp) at about midway. Acropodite subapically with a small tooth (t) dorsally and an evident digitiform lobe (lo) ventrally; seminal groove terminating without hairpad.