Eutrichodesmus steineri 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 : 44-46

Eutrichodesmus steineri Liu & Wesener sp. n. Figs 1A, 2, 3, 4

Material examined.

Holotype male (SMF), Laos, Luang Prabang Province, Phou Khoun District, Cave Tham Deu (E 48-013-005), N19°26'4.3", E102°29'16.6", 6.I.2007, coll. L. Price (205/07-).

Paratypes.

1 male (ZFMK MYR6130), 2 juveniles (ZFMK MYR6126), same data as holotype; 1 male, 5 females, 7 juveniles (SMF), same locality (E 48-013-005), 5.I.2007, coll. H. Steiner (210/07-); 1 female (ZFMK MYR6133), same data as above; 1 male, 1 female, 1 juvenile (SMF), same district, Cave Tham Dout (E 48-013-004), 5.I.2007, coll. L. Price (139/07-).

Etymology.

Honours Mr. H. Steiner, one of the collectors; noun.

Diagnosis.

Differs from other species of the genus in showing laterally 3-lobulated paraterga and the extremely high mid-dorsal projections on metaterga 5-19, the latter character very similar to that observed in Eutrichodesmus macclurei Hoffman, 1977, from western Malaysia ( Hoffman 1977). However, Eutrichodesmus steineri sp. n. is distinct from Eutrichodesmus macclurei in the gonopod, which has a long, digitiform, distofemoral process, vs. a short spiniform process in the counterpart. See also Key above.

Description.

Length of adults of both sexes ca. 9.5-10.0 mm, width 0.8-1.0 mm and 2.0-2.2 mm on midbody pro- and metazona, respectively.

Coloration uniformly grey-brown with pallid antennae (Fig. 1A).

Adults with 20 segments (Fig. 1A), body subcylindrical, conglobation complete.

Head slightly transverse, frons densely pilose, microgranular except for clypeus, with a paramedian pair of rounded, paramedian, microvillose knobs above antennal sockets (Fig. 2A). Epicranial suture conspicuous.

Antennae densely pilose, short, but slender, only slightly clavate (Figs 2A, 3A). In length, antennomere 6> 3> 2> 4 = 5> 7> 1. Antennomeres 5 and 6 each with an evident group of minute bacilliform sensilla dorso-apically; disc with four sensory cones apically (Figs 2A, 3A).

Labrum usually with three, rarely five teeth, lateral ones smaller (Fig. 2A).

Gnathochilarium (Fig. 3B) with a long bacilliform sensillum apically on each lamella lingualis (ll); mentum (m) triangular.

Mandible with a movable external tooth (et), an internal tooth (it) with four cusps; six pectinate lamellae (pl) consisting of long, smooth teeth; intermediate area (ia) covered with small cuticular scales; a large, stairs-like molar plate (mp) close to anterior fringe with pin-like structures (Fig. 3C).

Collum subtrapeziform (Fig. 2D), slightly broader than head, not covering the latter from above; dorsal surface with six transverse rows of round microvillose tubercles, flattened medially (Fig. 2D); each tubercle crowned by a 2-segmented seta, these setae being mostly abraded. Frontal margin slightly elevated (Fig. 2D).

Prozona very finely alveolate; stricture between pro- and metazona broad, shallow and smooth (Fig. 3D). Limbus regularly crenulate (Fig. 3 F–G). Endotergum smooth (Fig. 3G).

Metaterga 2-4 each with three transverse mixostictic rows of similar small tubercles extending onto paraterga (Fig. 2 B–C), 7(8) + 7(8) per row. Three transverse rows of very small, shallow, microvillose tuberculations on metaterga 5-19 (Fig. 2C, E, H–I), while metaterga 5-19 with a very high, large, mid-dorsal projection bifid on each side (Figs 1A, 2C, E, G–I). Projections 5-17 directed upright, then inclined slightly caudad on metaterga 18 and 19 (Fig. 2I). Metatergal setae 2-segmented, often abraded (Fig. 3 H–I).

Paraterga with evident shoulders anteriorly, strongly declivous, broad and usually trilobate laterally (Figs 2 H–I, 3E), evidently extending down below level of venter (Fig. 2G); caudolaterally at base with two distinct lobulations (Figs 2 H–I, 3E). Para terga 2 strongly enlarged, a lateral lobulation indistinct, but two caudolateral lobulations evident (Fig. 2B); paraterga 3 and 4 slightly shorter than others, bilobate laterally (Fig. 2B).

Pore formula normal (5, 7, 9, 10, 12, 13, 15-19), ozopores distinct, each located near top of caudolateral lobulation (Figs 2E, 3E, H).

Pre-anal ring short, with four transverse rows of very small and flat tuberculations (Fig. 2F, I). Epiproct apically with four spinnerets (Fig. 3L). Paraprocts and hypoproct densely microvillose; paraprocts with two pairs of long setae, hypoproct subtrapeziform, with two long setae (Fig. 2F).

Pleurosternal keels absent. Sterna very narrow (Fig. 2G), but much broader only between male coxae 6-7 and 9. Stigmata clearly visible (Fig. 3J). Gonopod aperture suboval.

Legs long and slender, nearly reaching tips of paraterga (Fig. 2G); tarsus longer than femur; claw simple, curved ventrad (Fig. 3K).

Gonopods (Figs 3 M–N, 4) simple. Coxae large, abundantly micropapillate and setose ventrolaterally. Telopodite slightly longer than coxite, slender throughout, subfalcate, distinctly curved ventrad, setose in its basal part, with a prominent, digitiform, lateral, distofemoral process (dp) at about basal one-third. Acropodite with a micropapillate process (pp) at midway; seminal groove long, terminating in a hairpad at a small, triangular, mesal lobule (lo) subapically.

Vulvae lying inside a membranous sac, each vulva consisting of a large horseshoe-shaped operculum (op) and a bursa (b) with several long setae (Fig. 3O).