Isohypsibius taibaiensis sp. nov. (Tardigrada, Hypsibiidae) from China Author Li, Xiaochen Author Wang, Lizhi text Zootaxa 2005 1036 55 60 journal article 10.5281/zenodo.169729 76b73b2c-7439-4a43-8e4a-491ed4108803 1175­5326 169729 Isohypsibius taibaiensis sp. nov. ( Fig. 1A–E , Table 1 ) Material examined: Holotype (Slide number MT0505001) and nine paratypes (Slide numbers MT0505002 – 010) were collected from the southern slope of Mount Taibai, the highest peak of Qinling Mountains (central part of China ), at an altitude of 2,200 m a.s.l. (33°48 N, 107°43 E). Mount Taibai is located in the central part of Shaanxi Province. All specimens are deposited at the College of Life Sciences, Shaanxi Normal University, P. R. China . Diagnosis: Medium in size. Colourless. Eyespots present. Cuticle smooth. Buccopharyngeal apparatus of Isohypsibius type . Buccal tube rather short and wide. Pharyngeal bulb almost round with robust apophyses, three short macroplacoids and a very small microplacoid. Claws of Isohypsibius type robust, slightly increasing in size from leg I to IV. Accessory points present on the principal branches of claws. Lunules present at the base of the claws. Sinuous cuticular bars present inside the base of the internal doubleclaws on the first three pair of legs. Description of the holotype : Medium in size (295.9 µm). Colourless. Eyespots present. Cuticle smooth. Mouth without peribuccal lamellae ( Fig. 1A – B ). Stylet furcae ( Fig. 1C ) with the posterior­lateral vertices rounded and swollen. Bucco­pharyngeal apparatus of Isohypsibius type (according to Pilato, 1982 ) ( Fig. 1C ). Buccal tube rigid, rather short (27.4 µm) and wide (4.8 µm OD); stylet supports inserted on the buccal tube at 58.03% of its length. Pharyngeal bulb almost round with robust apophyses, three macroplacoids and a very small microplacoid. The second macroplacoid the shortest (2.4 µm), the third macroplacoid the longest (4.5 µm), the first and the second almost in contact, the third considerably detached. Claws of Isohypsibius type ( Fig. 1D–E ) robust, slightly increasing in size from leg I to IV. Well­developed accessory points present on the principal branches of claws. Lunules present at the base of the claws, and the lunules very large on the claws of the 4th pair of legs. Sinuous cuticular bars present near the base of the internal double­claws on the first three pair of legs. Eggs unknown. Remarks: The paratypes are similar to the holotype as regards the qualitative characters. Etymology: Named after the type locality Mount Taibai. Differential diagnosis: Isohypsibius taibaiensis sp. nov. is similar to Isohypsibius macrodactylus ( Maucci, 1978 ) in having lunule at the base of the claws, in having very similar buccal­pharyngeal apparatus, sinuous cuticular bar near the base of the internal double­claws on the first three pair of legs, and long common basal branch; it differs from I. macrodactylus in having eyespots, relatively shorter claws, the claws of the 4th pair of legs not much greater than the others, in lacking irregular granules of black or brown pigment on dorsal side. TABLE 1. Dimensions (in µm) of Isohypsibius taibaiensis sp. nov. from Mount Taibai, Qinling Mountains, China . Holotype SMI* LMI* Mean ± SD * SMI, the smallest measured individual; LMI, the largest measured individual; BT, buccal tube; PB, primary branch; SB, second branch; SS, stylet support. Numbers in brackets represent the sample size.

µm	pt	µm	pt	µm	pt	µm	pt
Body	295.9	227.8	318.2	263.50±33.55 (10)
Buccal tube External diameter of BT* SS* insertion point	27.4 4.8 15.9	17.52 58.03	28.2 4.6 18.4	16.31 65.25	28.7 5.2 18.5	18.12 64.46	27.53±1.53 (10) 4.70± 0.31 (10) 17.66±1.16 (10)	17.01±1.26 (10) 64.16±4.05 (10)
Placoid row	13.6	49.64	12.8	45.39	13.3	46.34	13.01±0.80 (10)	47.22±1.78 (10)
First macroplacoid	3.4	12.41	3	10.64	3.1	10.8	3.01±0.22 (10)	10.93±0.61 (10)
Second macroplacoid	2.4	8.76	2.1	7.45	2.5	8.71	2.30±0.24 (10)	8.30±0.85 (10)
Third macroplacoid	4.5	16.42	3.2	11.35	4.4	15.33	3.95±0.52 (10)	14.24±1.66 (10)
Microplacoid	0.9	3.28	0.9	3.19	1.2	4.18	0.88±0.15 (10)	3.20±0.49 (10)
External claw PB* SB*	14.9 7.3	54.38 26.64	12.3 8.1	43.62 28.72	13.5 8.3	47.04 28.92	13.50±1.19 (10) 8.81±1.17 (10)	49.07±3.73 (10) 32.05±4.17 (10)
Internal claw PB*	12.6	45.96	9.9	35.11	10.8	37.63	10.84±1.21 (10)	39.50±4.97 (10)
SB* External claw PB* SB* Internal claw PB*	9.1 15.4 7.8 10.7	33.21 56.2 28.47 39.05	7.4 13.5 9.2 11.2	26.24 47.87 32.62 39.72	7.8 14.6 8.6 12.5	27.18 50.87 29.97 43.55	7.88±0.55 (10) 14.19±1.12 (10) 9.52±1.03 (10) 11.42±1.31 (10)	28.74±2.44 (10) 51.78±6.00 (10) 34.73±4.68 (10) 41.73±6.28 (10)
SB* External claw PB* SB*	8.1 16.2 10.7	29.56 59.12 39.05	10.6 14.1 9.4	37.59 50.00 33.33	8.1 16.2 10.4	28.22 56.45 36.24	8.39±1.00 (10) 14.39±1.22 (10) 9.38±1.06 (10)	30.61±4.26 (10) 52.43±5.29 (10) 34.05±3.18 (10)
Internal claw PB* SB* Posterior claw PB* SB*	14.7 9.2 18.8 10.2	53.65 33.58 68.61 37.23	10.5 8.6 18 11.5	37.23 30.50 63.83 40.78	14.1 9.2 18.8 12.3	49.13 32.06 65.51 42.86	12.03±1.74 (10) 8.16±0.92 (10) 19.97±1.15 (10) 11.26±1.20 (10)	43.95±7.54 (10) 29.61±2.62 (10) 65.40±4.84 (10) 40.94±4.24 (10)
Anterior claw PB* SB*	14.9 9.4	54.38 34.31	13.2 9.3	46.81 32.98	14.4 9.6	50.17 33.45	13.81±0.77 (10) 9.21±0.69 (10)	50.24±3.06 (10) 33.51±2.54 (10)

FIGURE 1. A–E, Isohypsibius taibaiensis sp. nov. : A, habitus showing the claws (holotype); B, habitus showing the bucco­pharyngeal apparatus (holotype); C, bucco­pharyngeal apparatus (holotype); D, claws on the third pair of legs (holotype); E, claws on the fourth pair of legs (holotype). (A–B: phase contrast). AB, scale bars =50µm; C–E, scale bars =10µm. Isohypsibius taibaiensis sp. nov. is similar to Isohypsibius deconincki Pilato, 1971 in having lunule at the base of the double­claws, in having the claws of the 4th pair of legs not much greater than the others; it differs from I. deconicki in having eyespots, accessory points on the principal branch of the claws and cuticular bar near the base of the internal claws on the first three pair of legs. Isohypsibius taibaiensis sp. nov. differs from Isohypsibius ceciliae Pilato & Binda, 1987 in lacking cuticular sculpture. Isohypsibius taibaiensis sp. nov. differs from Isohypsibius irregibilis Biserov, 1992 in having microplacoid, in having macroplacoids with different shape, in lacking rugose on cuticle and a similarity of projection at the base of the primary branchs. Isohypsibius taibaiensis sp. nov. differs from Isohypsibius arbiter ( Binda, 1980 ) in having different shape of the cuticular bars near the internal claws on the first three pair of legs, in lacking cuticular sculpture on dorsal side or the caudal portion of the body. Isohypsibius taibaiensis sp. nov. differs from Isohypsibius prosostomus Thulin, 1928 in having lunule at the base of the double­claws, in having different shape of the cuticular bars near the internal claws on the first three pair of legs, and in having a distance between the first and the second macroplacoid ( Ramazzotti & Maucci, 1983 ). Isohypsibius taibaiensis sp. nov. differs from Isohypsibius schaudinni ( Richters, 1909 ) in having the second macroplacoid shorter than the first one, in having the cuticular bars near the internal claws on the first three pair of legs ( Ramazzotti & Maucci, 1983 ).