Mixibius pilatoi, Wang, 2009

Wang, Lizhi, 2009, Tardigrades from the Yunnan-Guizhou Plateau (China) with description of two new species in the genera Mixibius (Eutardigrada: Hypsibiidae) and Pseudechiniscus (Heterotardigrada: Echiniscidae), Journal of Natural History 43 (41 - 42), pp. 2553-2570 : 2564-2568

Mixibius pilatoi sp. n.

( Figure 2A–D )

Material examined

Holotype (adult; slide no. GZ0708102), nine paratypes (adults; slide nos GZ 0708101, GZ 0708103–GZ0708110) were collected from Zhenning County, Guizhou Province, China (25°58′N, 105°41′E) at 1200 m asl. The specimens are deposited at the College of Life Sciences, Shaanxi Normal University, P. R. China.

Diagnosis

Medium size. Cuticle smooth, colourless, eyespots present. Bucco-pharyngeal apparatus of Mixibius type. Mouth ventral, without peribuccal lamellae. Buccal tube moderately wide, with appendices for the insertion of the stylet muscles in the form of a hook, without ventral lamina. Pharynx almost round with apophyses and two short, rod-shaped macroplacoids. First macroplacoid with constriction in middle, second macroplacoid shorter and without constriction. Microplacoid and septulum absent. External claws of Isohypsibius type, inner claws of modified Isohypsibius type, angle between basal portion and secondary branch is larger than 90°. Accessory points present on the primary branches of claws. Smooth lunules present at the base of the claws on all legs. No other cuticular thickening is present on the legs.

Description

Medium size (see Table 3). Cuticle smooth, body colourless. Black eyespots present (see Figure 2A ). Bucco-pharyngeal apparatus of Mixibius type (see Figure 2B ). Mouth ventral, without peribuccal lamellae or papulae. Rigid buccal tube moderately wide, with appendices for the insertion of the stylet muscles in the form of a hook, without ventral lamina. Pharynx almost round with apophyses and two short, rod-shaped macroplacoids. First macroplacoid with constriction in middle, second macroplacoid shorter and without constriction. Microplacoid and septulum absent (see Figure 2B ). External claws of Isohypsibius type, inner claws of modified Isohypsibius type, angle between basal portion and secondary branch is larger than 90° (see Figures 2C, D ). Accessory points present on the primary branches of claws. Smooth lunules present at the base of the claws on all legs but better developed on legs IV (see Figures 2C, D ). No other cuticular thickening is present on the legs. Eggs unknown.

Etymology

This species is dedicated to Dr Giovanni Pilato, professor at Dipartimento di Biologia Animale “Marcello La Greca” dell’Università, Catania, Italy.

Remarks

This species can be differentiated from M. saracenus Pilato, 1973 and M. fueginus Pilato and Binda, 1996 by its shorter macroplacoids, and the presence of lunulae; it is differentiated from M. ninguidus Biserov, 1999 , M. ornatus Pilato, Binda, Napolitano, and Moncada, 2002 , M. sutirae Pilato, Binda, and Lisi, 2004 and M. tibetanus Li and Li, 2008 by a smooth cuticle and greater body length.

Character Holotype LMI SMI Mean ± SD

µm pt µm pt µm pt µm pt Body 305.6 322.5 182.8 262.67 ± 16.55 (10)

Buccal tube 39.1 38.7 29.9 35.29 ± 1.11 (10)

SS insertion point 28.6 73.14 28.6 73.90 20.3 67.89 24.74 ± 1.24 (10) 69.47 ± 3.32 External diameter of BT 3.2 8.18 3.6 9.30 2.3 7.69 2.94 ± 0.12 (10) 8.35 ± 0.44 Pharyngeal bulb length 36.9 94.37 37.2 96.12 25.5 85.28 32.21 ± 1.58 (10) 90.41 ± 5.54 Pharyngeal bulb width 35.1 89.77 35.1 90.70 23.4 78.26 30.22 ± 1.63 (10) 84.56 ± 6.38 First macroplacoid 5.2 13.30 5.2 13.44 3.4 11.37 4.22 ± 0.19 (10) 11.76 ± 0.69 Second macroplacoid 3.4 8.69 3.6 9.30 2.2 7.36 2.87 ± 0.14 (10) 8.02 ± 0.49 Macroplacoid row 10.7 27.37 10.9 28.17 7.8 26.09 9.58 ± 0.32 (10) 27.11 ± 1.23 External claw I BC 5.6 14.32 5.8 14.99 4.8 16.05 5.35 ± 0.24 (8) 15.32 ± 0.51 External claw I PB 10.1 25.83 10.3 26.62 8.5 28.43 9.52 ± 0.44 (8) 27.29 ± 0.78 External claw I SB 6.5 16.62 6.8 17.57 5.8 19.40 6.34 ± 0.23 (8) 18.26 ± 0.81 Internal claw I BC 4.7 12.02 4.8 12.40 3.9 13.04 4.33 ± 0.22 (8) 12.41 ± 0.31 Internal claw I PB 8.3 21.22 8.5 21.96 6.9 23.08 7.71 ± 0.39 (8) 22.09 ± 0.57 Internal claw I SB 5.8 14.83 5.8 14.99 5.2 17.39 5.58 ± 0.19 (8) 16.14 ± 0.62 External claw II BC 5.9 15.09 6.1 15.76 5.1 17.06 5.55 ± 0.24 (6) 15.92 ± 0.56 External claw II PB 10.5 26.85 10.9 28.17 8.9 29.77 9.85 ± 0.46 (6) 28.19 ± 0.93 External claw II SB 6.8 17.39 7.2 18.60 6.2 20.74 6.73 ± 0.23 (6) 19.22 ± 0.91 Internal claw II BC 4.9 12.53 5.0 12.92 4.1 13.71 4.58 ± 0.22 (6) 13.14 ± 0.35 Internal claw II PB 8.7 22.25 8.8 22.74 7.3 24.41 8.13 ± 0.37 (6) Internal claw II SB 6.0 15.35 6.2 16.02 5.5 18.39 5.98 ± 0.23 (6) External claw III BC 6.1 15.60 6.3 16.30 5.2 17.39 5.73 ± 0.26 (5) External claw III PB 10.8 27.62 11.2 28.94 9.3 31.10 10.21 ± 0.43 (5) External claw III SB 7.0 19.70 7.7 19.90 6.5 21.74 7.13 ± 0.28 (5) Internal claw III BC 5.1 13.04 5.1 13.18 4.4 14.72 4.82 ± 0.18 (5) Internal claw III PB 8.9 22.76 9.2 23.77 7.8 26.09 8.55 ± 0.33 (5) Internal claw III SB 6.5 16.62 6.7 17.31 5.8 19.40 6.38 ± 0.23 (5) Posterior claw IV BC 7.5 19.18 7.1 18.35 5.9 19.73 6.65 ± 0.36 (7) Posterior claw IV PB 13.3 34.02 12.5 32.30 10.6 35.45 11.83 ± 0.61 (7) Posterior claw IV SB 8.8 22.51 8.5 21.96 7.1 23.75 7.98 ± 0.41 (7) Anterior claw IV BC 6.6 16.88 6.2 16.02 5.0 16.72 5.71 ± 0.35 (7) Anterior claw IV PB 11.6 29.67 10.9 28.17 8.8 29.43 10.08 ± 0.61 (7) Anterior claw IV SB 7.9 20.20 7.7 19.90 6.5 21.74 7.23 ± 0.37 (7) 23.41 ± 0.66 17.16 ± 0.72 16.41 ± 0.54 29.23 ± 1.08 20.61 ± 0.68 13.89 ± 0.49 24.54 ± 0.95 18.32 ± 0.78 19.43 ± 0.22 34.62 ± 0.43 23.20 ± 0.41 16.66 ± 0.11 29.45 ± 0.19 20.97 ± 0.38

Notes: SMI, smallest measured individual; LMI, largest measured individual; BC, basal claw; BT, buccal tube; PB, primary branch; SB, second branch; SS, stylet support.

Genus Diphascon (Diphascon) Plate, 1889

Figures

Figure 2. Mixibius pilatoi sp. n. (A) Habitus focused to show the claws (holotype); (B) buccopharyngeal apparatus (holotype); (C) claws on the third pair of legs (holotype); (D) claws on fourth pair of legs (holotype). Scale bars: 60 µm (A); 20 µm (B); 10 µm (C, D).