Pseudechiniscus chengi, Xue, Jing, Li, Xiaochen, Wang, Lizhi, Xian, Panpan & Chen, Huiqing, 2017

Xue, Jing, Li, Xiaochen, Wang, Lizhi, Xian, Panpan & Chen, Huiqing, 2017, Bryochoerus liupanensis sp. nov. and Pseudechiniscus chengi. sp. nov. (Tardigrada: Heterotardigrada: Echiniscidae) from China, Zootaxa 4291 (2), pp. 324-334 : 328-331

Pseudechiniscus chengi sp. nov.

( Table 2, Figs. 4–7 )

Material examined. Holotype (slide number: xnc02001) and four paratypes (slide numbers: xnc02002, xnc02005, xnc02011, and xnc02013).

Type locality. Same as Bryochoerus liupanensis sp. nov.

Type depository. Same as Bryochoerus liupanensis sp. nov.

Diagnosis. Colour brown. Eye spots present. Cephalic papilla dome-shaped. Cirrus A short. Frontal plate faceted. Median plates undivided. Third median plate present, but sometimes weakly developed or not visible. Pseudosegmental plate with longitudinal median fold, the posterior margin of the pseudosegmental plate without any projection. Terminal plate with well-developed incisions. All plates and upper part of all legs with cuticular sculpture composed of round dots differing in size. Striae absent between dots. Lateral intersegmental plates absent. Ventral side of the body without plate. Papilla present on legs IV. Dentate collar absent on legs IV. Very small spur present on the internal claws on all legs.

Description. Body colour brown. Eyes present. Head tapered and long at the rostral end, body slender ( Fig. 4 a). Apart from head appendages, only lateral appendages cirri A present. Cirrus A short. Primary clava is a papilla. The cephalic papilla dome-shaped, short and thick, well developed ( Fig. 4 b). Stylets present, stylet supports absent (or not visible after slide preparation), buccal tube long and narrow, pharyngeal bulb round ( Fig. 5 b). Head plate with W-shaped fold, two short longitudinal ridges connected to the angles of the W-shaped fold respectively. Anterior part of the scapular plate with a short longitudinal middle ridge, posterior part of scapular plate transversely divided into four parts. Dorsal plates contain first undivided median plate, first paired plates, second undivided median plate, second paired plates, pseudosegmental plate and the terminal plate, third median plate present (holotype and xnc02005) ( Fig. 4 a), but sometimes weakly developed or not visible (xnc02002, xnc02011 and xnc02013) ( Fig. 5 a), if present, rhombic and undivided. Pseudosegmental plate with a longitudinal median fold. Lobes, spines, or any other projections on posterior margin of the pseudosegmental plate absent. Terminal plate with two well developed incisions on each side. Lateral intersegmental plates absent. All dorsal plates have a dense and regular ornamentation comprised of dots, dot round-shaped and differing in size, dots on the paired plates larger than the ones on unpaired plates ( Figs. 4 a, 6). Diameter of the largest dot up to 0.86 μm. Ventral side of body without plates.

All legs without spines. Fourth pair of legs without dentate collar but with a small papilla ( Fig. 7 a). The upper part of all legs covered with plates and ornamentation composed of dots similar to those on dorsal plates ( Fig. 7 a), but smaller. A very thin spur pointed backward the claw base is present on internal claws of all legs ( Figs. 4 b, 7b).

Etymology. This species is dedicated to Prof. Guangxu Cheng, President of Shaanxi Normal University, for his contributions to the development of our university.

Structure xnc02001 xnc02002 xnc02005 xnc02011 xnc02013

female female female female female Differential diagnosis. Pseudechiniscus chengi sp. nov. is similar to Pseudechiniscus bartkei Węglarska 1962 (North Viet Nam), Pseudechiniscus gullii ( Pilato & Lisi 2006) ( Southern Mexico ), Pseudechiniscus novaezeelandiae novaezeelandiae ( Richters 1908) ( New Zealand), Pseudechiniscus quadrilobatus Iharos 1969 (Viet Nam), Pseudechiniscus santomensis Fontoura et al. 2010 ( Democratic Republic of São Tomé and Príncipe), Pseudechiniscus spinerectus Pilato et al. 2001 ( Ecuador) , and Pseudechiniscus yunnanensis Wang 2009 (Yunnan, China), in having a similar cuticular sculpture on the dorsal plates. The new species differs from the above species mainly by lacking the striae between cuticular granules. In addition, Pseudechiniscus chengi sp. nov. differs from P. bartkei in lacking the bilobed process on the caudal margin of the pseudosegmental plate; and from P. gullii in lacking the triangular lobe on the posterior margin of the pseudosegmental plate, and in having spur on the internal claws on all legs. The new species differs from P. n. novaezeelandiae by the undivided median plates 1 and 2, and in lacking spines on the caudal margin of the pseudosegmental plate; and from P. quadrilobatus in lacking the uplifted lobes on the posterior margin of the dorsal plates, and pseudosegmental plate along the median line. Pseudechiniscus chengi sp. nov. it differs from P. santomensis in lacking the tiny projections on the caudal margin of the pseudosegmental plate, and by undivided pseudosegmental plate; and differs from P. spinerectus in lacking the triangular spines on the caudal margin of the pseudosegmental plate. The new species differs from P yunnanensis in lacking the triangular spines on the caudal margin of the pseudosegmental plate, and in having notches on the terminal plate.

Figures

FIGURE 4. Pseudechiniscus chengi sp. nov. (holotype). a, habitus in dorsal view focused to show the cuticular sculpture on the dorsal plate at 400 × magnification; b, habitus in ventral view focused to show the claws at 400 × magnification. Scale bars = 30 µm.

FIGURE 5. Pseudechiniscus chengi sp. nov. (xnc 02011). a, habitus in dorsal view focused to show the dorsal plates at 400 × magnification; b, habitus focused to show the buccal apparatus at 400 × magnification. Scale bars = 30 µm.

FIGURE 6. Pseudechiniscus chengi sp. nov. (holotype). Part of dorsal plate (median plate 2, paired plate 2, median plate 3 and partial pseudosegmental plate) in dorsal view focused to show the cuticular sculpture under oil lens at 1000 × magnification. Scale bar = 20 µm.

FIGURE 7. Pseudechiniscus chengi sp. nov. (holotype). a, hind legs focused to show the ornamentation and the papilla; b, claws on the hind legs focused to show the tiny spur on the internal claws. Photos taken at 1000 × magnification. The arrows pointed at the papillae (figure 7 a) and spur respectively (figure 7 b). Scale bars = 10 µm.