Hyleoglomeris reducta, 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 : 899-901

Hyleoglomeris reducta n. sp.

( Fig. 7 )

TYPE MATERIAL. — China. Yunnan Province, Jianshui County, Yan Dong Cave , 12.I.1989, leg. P. Beron, holotype ♂ ( NMNHS), paratypes 20 ♂♂, 12 ♀♀ ( NMNHS) ; 3 ♂♂, 2 ♀♀ ( MNHN CC155 ) ; 3 ♂♂, 2 ♀♀ ( ZMUM) .

ETYMOLOGY. — To emphasize the coloration, hyposchism and the number of the striae crossing the thoracic shield, all strongly reduced.

DIAGNOSIS. — Differs from congeners by the strongly reduced coloration and hyposchism, combined with certain details of telopod structure.

DESCRIPTION

Length 5.5-7.5 (♂) or 6.0- 8.5 mm (♀), width 2.8-3.6 (♂) or 3.0-4.0 mm (♀). Holotype 7.5 mm long and 3.7 mm wide.

Coloration usually entirely pallid, only in few paratypes (5 ♂♂, 1 ♀) with remnants of pigment expressed as head being light red-brown above antennal sockets, and antennae brown; in one of these males a light red-brownish tergal pattern is also retained as large, transverse, apparently marbled, paramedian spots nearly in touch anteromedially on terga 3-11 and pygidium, and as increasingly small sublateral spotlets on terga 3-8.

Antennomere 6 about 2.5 times longer than wide; ocelli 6 + 1 to 7 + 1, unpigmented, convex, especially evident in pigmented specimens; Tömösváry’s organ transverse-oval, only slightly wider than long.

Collum with two transverse striae.

Thoracic shield with a very small and narrow hyposchism not reaching the caudal tergal contour ( Fig. 7A ); 6 or 7 transverse striae, of which 4 or 5 start above the schism and (1)2-3 ones (never the first and last though) cross the dorsum.

Male pygidium virtually not sinuate medially at caudal margin.

Male leg 17 ( Fig. 7B ) with a low outer coxal lobe; telopodite 4-segmented.

Male leg 18 ( Fig.7C ) with a more or less narrowly ogival syncoxital notch; telopodite 4-segmented.

Telopods ( Fig.7D ) with a rather high and roundly subtrapeziform syncoxital lobe flanked by two setose horns crowned with an apical setoid. Prefemur micropapillate laterally. Caudomedial outgrowth of tibia with a micropapillate tubercle at base. Tarsus rather modestly rounded apically.

REMARKS

Only one cavernicolous congener has hitherto been described from China in general and from Yunnan in particular: H. albicorporis Zhang & Zhang, 1995 , from Shihua Cave at Baoshan. Based only on three specimens, which were described quite superficially ( Zhang & Zhang 1995), it is hard to decide whether H.albicorporis is indeed devoid of pigmentation, and thus whether it differs from some other, especially endogean, congeners encountered in SE China (see also below). It matches H. reducta n. sp. quite closely, not only on geographical grounds, but also in terms of at least body size and the conformation of male legs 17-19. The only meaningful differences between these two species that can be drawn from the original description of H. albicorporis concern the latter’s ordinary (i.e. small) hyposchism, a slenderer male telopodite 17, and the tip of the telopod syncoxital horns supplied with a subapical, rather than apical, setoid.

The fact that only a few (6 of 42, or c. 14%) specimens from the type series of H. reducta n. sp. still retain pigment, and only one shows some traces of a tergal pattern, is important, apparently reflecting an intermediate stage of evolution toward complete cavernicoly. Whether or not H. reducta n. sp. is already a troglobite is impossible to decide based solely on the above morphological and geographical evidence. The colour pattern of the single particularly “atavis- tic” male in the sample strongly resembles that of H. maculata , but differs in the paramedian spots being nearly in touch anteromedially. In addition, H. reducta n. sp. shows an even more strongly reduced hyposchism and less numerous striae on the thoracic shield.

In general, Yunnan is among China’s provinces particularly rich in karst caves that support numerous troglobitic animals ( Chen et al. 2001). Yan Dong Cave is known to contain several troglobitic arthropods, including the millipede Bollmania beroni Stoev & Enghoff, 2005 (cf. Stoev & Enghoff 2005).

Figures

FIG. 7. — Hyleoglomeris reducta n. sp., ♂ paratype: A, lateral side of thoracic shield; B, leg 17; C, leg 18; D, telopod, caudal view. Scale bar: A, drawn not to scale; B-D, 0.4 mm.