Hyleoglomeris xuxiakei, Liu, Weixin & Wynne, J. Judson, 2019

Liu, Weixin & Wynne, J. Judson, 2019, Cave millipede diversity with the description of six new species from Guangxi, China, Subterranean Biology 30, pp. 57-94 : 65-68

Hyleoglomeris xuxiakei sp. nov. Figs 3B , 7 , 8

Type material.

Holotype male (SCAU), China, Guangxi Zhuang Autonomous Region, Yangshuo County, Guanshan No. 4 Cave [24°56'58.34"N, 110°20'53.52"E], 186 m el., deep zone, direct intuitive search, 16 November 2016, J.J. Wynne leg. Paratype, 1 male (SCAU), same data as holotype. 3 females (SCAU), same data as holotype, but deep zone, slightly muddy flat area.

Etymology.

The species name, xuxiakei, was Latinized using a combination of the surname and forename of Xu Xiake (徐霞客). Xu was a traveler, explorer, and the first speleologist of China, who studied caves and karst geology during the decline of the Ming Dynasty. He conducted a four-year expedition (1636-1640) across southern China where he examined over 300 caves (including more than 100 from the Guilin area; Sweeting 1995, Ravbar 2016). In his book, Xu Xiake’s Travels (first published in 1642), he described underground streams and ponds, provided sketch maps of caves, as well as proposed terminology for karst features; many of his speleological terms are still used today ( Ravbar 2016).

Diagnosis.

Adult male of H. xuxiakei sp. nov. is distinct from other Hyleoglomeris species based on the following combination of characters: (1) nearly pallid color ( Fig. 7 ); (2) ♂ leg 17 with 3-segmented telopodite ( Fig. 8A ); (3) telopods with a low, oval-shaped, central syncoxital lobe; (4) horns of syncoxital lobe without any structure on top ( Fig. 8D ). This new species is clearly distinguished by the depigmented body ( Fig. 3B ) vs. vivid color pattern in H. rukouqu sp. nov. ( Fig. 3A ).

Description.

Based on type specimens. Lengths of body ca 3.8-4.5 mm, width 2.5 -3.0 mm in both sexes. Coloration: entirely pallid ( Figs 3B , 7 ). Head: Ommatidium at least 5(6) + 1, translucent, barely visible ( Fig. 7C ). Tömösváry’s organ transverse-oval, parallel to the body, only slightly wider than long. Antennae with four apical cones, antennomere 6 ca 2.0 (♂) or 1.8 (♀) times as long as wide. Exoskeleton: Collum with two transverse striae ( Fig. 7C ). Thoracic shield with a narrow hyposchism, the latter reaching behind caudal tergal margin; 8-9 transverse striae: 4(5) starting below, one level to, 3(4) above schism; 5 striae (never the first and last from below) crossing the dorsum. Following terga 3-11 with two striae above lateral edge. Pygidium of both sexes regularly rounded at caudal margin. ♂ leg 17 with a low, subrounded, outer coxal lobe; telopodite 3-segmented ( Fig. 8A ). ♂ leg 18 with an arch-shaped syncoxital notch; telopodite 4-segmented ( Fig. 8B ). Telopods: ( Fig. 8 C–D ) with a rather low, oval-shaped, transverse, central syncoxital lobe flanked by high setose horns, each of the latter without any structure on top. Prefemur micropapillate laterally, with a well-developed frontomesal trichostele. Femur with a smaller frontomesal trichostele. Caudomesal femoral process prominent, apically with an evident lobe strongly curved to frontad. Tibia with a frontomesal seta. Caudomesal tibial process evident, recurved; a distinct, papillate tubercle at base on caudal face. Tarsus strongly sigmoid, narrowly rounded apically.

Habitat.

This species was collected from a chamber within the estimated cave deep zone, approximately 50 m from the cave entrance. Cave sediment was compact mud with a small amount of rock breakdown from the ceiling.

Notes.

Based on a depigmented habitus and translucent ommatidia, we consider this species is a troglobiont.

Figures

Figure 3. A Hyleoglomeris rukouqu sp. nov. from Shangshuiyan Cave B Hyleoglomeris xuxiakei sp. nov. from Guanshan No. 4 Cave C Hylomus yuani sp. nov. from Liangfeng Cave D Eutrichodesmus jianjia sp. nov. from Guanshan No. 4 Cave.

Figure 7. Hyleoglomeris xuxiakei sp. nov., holotype. A-C Habitus, dorsal, lateral and ventral views, respectively.

Figure 8. Hyleoglomeris xuxiakei sp. nov., holotype. A Leg 17, anterior view B leg 18; anterior view C right half of telopods, posterior view D right half of telopods, anterior views.