Hyleoglomeris sulcostriata, Golovatch & Geoffroy & Mauriès, 2006

Golovatch, Sergei I., Geoffroy, Jean-Jacques & Mauriès, Jean-Paul, 2006, Review of the millipede genus Hyleoglomeris Verhoeff, 1910 (Diplopoda, Glomerida, Glomeridae), with descriptions of new species from caves in Southeast Asia, Zoosystema 28 (4), pp. 887-915 : 902-904

Hyleoglomeris sulcostriata n. sp.

( Fig. 10 )

TYPE MATERIAL. — Laos. Vang Vieng, Tham Non (102.433°E, 18.951°N), cave, 1.I.2000, leg. L. Deharveng & A. Bedos, holotype ♂ ( MNHN CC158 ) ; paratypes 1 ♀ ( MNHN CC158 ) ; 1 ♂ ( ZMUM). — Khammouan Province, Ban Vieng, Tham Houai Sai (104.937°E, 17.552°N), sink cave, 13.II.2001, leg. X. Noguès, paratype ♂ ( MNHN CC158 ). — Same province , Ban Nam Non, Nam Non (104.688°E, 18.027°N), cave, 15.II.1999, leg. J. Lordon, paratypes 1 ♂, 1 ♀ ( MNHN CC158 ) .

ETYMOLOGY. — To emphasize a conspicuous lateral sulcus on the thoracic shield turning into a stria middorsally.

DIAGNOSIS. — Differs from congeners in some troglomorphic traits, combined with a conspicuous lateral sulcus on the thoracic shield turning into a stria middorsally.

DESCRIPTION

Length 5.0-6.0 (♂) or 5.5-7.0 mm (♀), width 2.5-3.0 (♂) or 2.8-3.5 mm (♀). Holotype 6.0 mm

long and 2.8 mm wide.

Coloration entirely pallid, unpigmented.

Antennomere 6 about 1.6-1.7 times longer than wide, antennomere 7 very short; 5 or 6 poorly visible, unpigmented but convex ocelli on each side of head; Tömösváry’s organ transverse-oval, about twice as wide as long.

Collum with two transverse striae.

Thoracic shield with a medium-sized hyposchism slightly surpassing the caudal tergal contour; 10 or 11 transverse striae, of which 8 or 9 start above the schism and 7 or 8 cross the dorsum; most of the striae lying on an elevation just in front of a conspicuous, rather strongly and regularly curved (like the other striae), midway, lateral sulcus delimiting a slight impression in posterolateral portion of the shield; the sulcus deep basally, starting just at schism end, gradually turning into the last crossing stria in apical third of the shield.

Male pygidium virtually not sinuate medially at caudal margin.

Male leg 17 ( Fig. 10A, E, H ) with a low to medium-sized, more or less rounded, sometimes micropapillate outer coxal lobe; telopodite 4-segmented.

Male leg 18 ( Fig. 10B, F, I ) with a broadly rounded to ogival syncoxital notch; telopodite 4-segmented.

Telopods ( Fig. 10C, D, G, J ) somewhat variable, with a roundly subtrapeziform to large and emarginate syncoxital lobe flanked by two setose horns crowned with a subapical setoid. Prefemur micropapillate laterally. Caudomedial outgrowth of femur rather narrow, that of tibia with a distinct to very prominent tubercle at base. Tarsus narrowly rounded apically, subacuminate.

REMARKS

As the material comes from three different caves in Laos, with a distance between both Khammouan caves of about 60 km (although located in the same karst area), which in turn are separated from Tham Non by a distance of about 300 km, variation is certainly something to expect. The specimens from the Khammouan caves appear to be particularly similar. They are slightly larger in size (3.0- 3.5 mm wide), there are usually seven striae crossing the thoracic shield while the respective male legs 17-19 are nearly identical, with an unusually high tubercle at base of the telopod tibial outgrowth ( Fig. 10 E-J). In contrast, the sample from Tham Non is distinct in that the animals are a little smaller (width 2.5-2.8 mm), usually showing eight striae crossing the thoracic shield, while male legs 17-19 are slightly different ( Fig. 10 A-D).

Nevertheless, there can be no doubt that the samples are conspecific because of the striking midway sulcus present on the thoracic shield.A similar sulcus is only known to occur in H. eusulcata n. sp., from Guizhou (see above), attesting to their particularly close relations. However, in H. sulcostriata n. sp. this sulcus gradually turns middorsally into the last stria crossing the shield.

This species also shows such troglomorphic features as complete depigmentation and an elongate Tömösváry’s organ, but the ocelli are still discernible and neither the antennae nor the legs are particularly elongate. To prove that we face a troglobite, additional observations and material are necessary.

In general, Laos is rich in karst caves that support numerous troglobites, presumably several among diplopods as well ( Besson et al. 2001).

Figures

FIG. 10. — Hyleoglomeris sulcostriata n. sp., ♂ holotype (A-D), ♂ paratype from Nam Non (E-G) and ♂ paratype from Tham Houai Sai (H-J); A, E, H, leg 17; B, F, I, leg 18; C, G, J, telopods, front view; D, distal part of telopod, caudal view. Scale bars: A-D, 0.3 mm; E-J, 0.4 mm.