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).