Doryphoribius chetumalensis, Pérez-Pech & Anguas-Escalante & Cutz-Pool & Guidetti, 2017

Pérez-Pech, Wilbert Andrés, Anguas-Escalante, Abril, Cutz-Pool, Leopoldo Querubin & Guidetti, Roberto, 2017, Doryphoribius chetumalensis sp. nov. (Eutardigrada: Isohypsibiidae) a new tardigrade species discovered in an unusual habitat of urban areas of Mexico, Zootaxa 4344 (2), pp. 345-356 : 347-352

Doryphoribius chetumalensis sp. nov.

Description of holotype ( Figs 2–4 ; Table 2).

Body colour orange. Cuticle of dorsal and ventral surfaces, and legs, smooth (i.e. without gibbosities or sculpture; Fig. 2 ). Eye spots present ( Figs 2C , 3A ). Bucco-pharyngeal apparatus of Doryphoribius type (see: Pilato & Binda 2010; Guidetti et al. 2013b) ( Fig. 3 ). Peribuccal structures and oral cavity armature absent or not visible under LM. Mouth antero-ventral. Ventral lamina present. Stylet furca of typical shape with two condyles and two proximal apophyses. Pharyngeal bulb spherical, with triangular pharyngeal apophyses, and three macroplacoids, without constrictions, and of similar length; microplacoid and septulum absent. Macroplacoids bean-shaped in lateral view; in dorsal view, the first triangular-shaped, the second rectangular-shaped, the third heart-shaped ( Fig. 3 ). First and second macroplacoids close together, the third macroplacoid more distant. Claws long, of Isohypsibius type, similar in size and shape on all legs ( Fig. 4 ). Claws with enlarged and wide bulbous bases; generally, the external claws of first three pairs of legs and the posterior claw of the hind legs with larger bulbous bases ( Fig. 4 ). Claw lunules absent. Primary branches of all claws with thin, short accessory points.

Morphometric data of the holotype and eight paratypes are reported in Table 2.

Remarks. Paratypes, body length from 188.8 µm to 345.7 µm. The eye spots and the orange colour of the body were visible in live specimens but not in all mounted specimens. Two exuviae were collected, which had eleven and twelve smooth eggs.

Type repositories. Holotype and 20 paratypes. Holotype and nine paratypes deposited in the Laboratory of Zoology , Chetumal Institute of Technology, Quintana Roo, Mexico ; 11 paratypes in the Bertolani collection, Department of Life Sciences , University of Modena and Reggio Emilia, Italy .

Character ind 10 ind 2 ind 5 ind 8 ind 9 ind 1 ind 6 holotype ind 4 µm pt index Type locality: Urban zone of Chetumal , Quintana Roo, Mexico, Petcacab street intersection with Tres Garantias street (site S1: 18°30'13"N, 88°18'19"W; 9 m a.s.l.). The substrate was soil sediment with a very clay texture accumulated on the street between the sidewalk and the asphalt (site S 1 in Table 1).

Other sites of collection. S2, Erick Paolo Martines street intersection with Colibri street; S3, Petcacab street intersection with Polyuc street; S4, Jesus Urueta street intersection with Heriberto Frias street (see Table 1).

Etymology. The name ‘ chetumalensis ’ refers to the locality in which the new species was found.

Differential diagnosis. Doryphoribius chetumalensis sp. nov. differs from all the other species of the genus in the distinctly enlarged and wide bulbous base to the claws ( Fig. 4 ). The new species belongs to the zappaloi group (see: Michalczyk & Kaczmarek 2010), having no dorsal cuticular gibbosities and three macroplacoids. With reference to the other species within this group, D. chetumalensis sp. nov. differs, not only by the wide bulbous basal claws, but also in other characters.

- Doryphoribius turkmenicus Biserov, 1999 was described as “white or slightly yellow” ( Biserov 1999) and with a well-developed anterior band of large teeth, while the new species has distinctly orange body colour, and has no visible oral cavity armature;

- Doryphoribius mexicanus Beasley et al., 2008 , and Doryphoribius bertolanii Beasley & Pilato, 1987 , were described with very simple oral cavity armature, composed of a single large round dorsal tooth placed in a posterior position ( Beasley et al. 2008; Beasley & Pilato 1987), which is absent in D. chetumalensis sp. nov.;

- Doryphoribius zappalai Pilato, 1971 has lunules in the claws which are absent in the new species;

- Doryphoribius korganovae Biserov, 1994 was described as yellowish brown with smooth or slightly rugose cuticle (Biserov 1994), while D. chetumalensis sp. nov. has an orange colour and smooth cuticle; the claw bases of D. korganovae are expanded, but not as enlarged as the new species;

- Doryphoribius qinlingense Li et al., 2004 was described as colourless, and with three macroplacoids increasing in length from first to third (Li et al. 2004), in the new species the three macroplacoids are of similar size; claw bases of D. qinlingense are expanded but not enlarged and bulbous, as in the new species;

- Doryphoribius longistipes Bartels et al., 2008 was described as having no lunules or cuticular thickening (Bartels et al. 2008), making the swollen and bulbous bases of D. chetumalensis sp. nov. very distinctive in comparison;

- Doryphoribius taiwanus Li & Li, 2008 was described as colourless and with a cuticular sculpture of dorsal and lateral tubercles (Li & Li 2008), which are absent in D. chetumalensis sp. nov.

Figures

FIGURE 2. Doryphoribius chetumalensis sp. nov.. Habitus A) Dorsal view (holotype). B) Lateral view. C) Ventral view (arrow = eye spot). Scale bars = 50 µm.

FIGURE 3. Doryphoribius chetumalensis sp. nov.. Buccal-pharyngeal apparatus. A) Macroplacoids in lateral view, stylet support and stylet furca (arrow = eye spot). B) Macroplacoids in dorsal view. C) Lateral view (arrow = ventral lamina). Scale bars = 10 µm.

FIGURE 4. Doryphoribius chetumalensis sp. nov.. Claws. A) Claws on second and third legs. B) Claw of second pair of legs. C) Claws of the fourth pair of legs. D) Claws of the third pair of legs. E) Claws of the fourth pair of legs. F) Claws of the fourth pair of legs. Arrows = bases of the external or posterior claws in the pair of claws in a leg. Scale bars = 10 µm.