RENAUDARCTIDAE Kristensen & Higgins, 1984

Fontoura, Paulo, Bartels, Paul J., Jørgensen, Aslak, Kristensen, Reinhardt Møbjerg & Hansen, Jesper Guldberg, 2017, A dichotomous key to the genera of the Marine Heterotardigrades (Tardigrada), Zootaxa 4294 (1), pp. 1-45 : 31-32

1.6 RENAUDARCTIDAE Kristensen & Higgins, 1984 (emended by Hansen et al. 2012)

Arthrotardigrades with segmental dorsal and ventral plates, both claws and toes present. Four toes are accompanied by four accessory claw spines19 on each foot in the adults. Primary and secondary clavae, and a complete set of cephalic cirri present.

1.6.1 Renaudarctu s Kristensen & Higgins, 1984 (emended by Hansen et al. 2012) ( Figs 5 A, 11C)

Renaudarctidae with segmental dorsal plates, two dorsal intersegmental plates, four dorsal intersegmental ridges33, a dorsal plate on each leg, and thin ventral plates. Each body plate with a pair of lateral spines. Caudal

32. In the terminology of this key “dorsal bristle” = accessory point.

33. According to Hansen et al. (2012), these intersegmental ridges are prominent cuticular structures forming a ridge rather than a true plate, present between segmental and intersegmental plates.

plate with two pairs of lateral spikes, one pair of caudal spikes, and lateral margins continuous with furca-like caudal extensions. Complete set of cephalic sense organs. Leg IV with small ovoid papilla; all other legs lack sensory structures. Cirrus E with cirrophore. Female and male with ovoid gonopore papillae adjacent to terminal anal system. Female with latero-ventral projections containing seminal receptacles.

Type species: Renaudarctus psammocryptus Kristensen & Higgins, 1984

Remark: During the publication process of this paper a new genus and species, Nodarctus hallucis Fujimoto &Yamasaki, 2017, of Renaudarctidae have been described and, consequently, the diagnosis of the family has been emended. The genus Nodarctus can be easily distinguished from Renaudarctus in having leg IV with two digits, subdivided dorsal body plates without lateral processes, and a large single caudal spike (see Fujimoto & Yamasaki 2017).

Figures

FIGURE 5. Habitus drawings of marine heterotardigrades. A Renaudarctus, redrawn from Hansen et al. (2012). B Megastygarctides, redrawn from McKirdy et al. (1976). C Faroestygarctus, redrawn from Hansen et al. (2012). D Stygarctus, redrawn from McKirdy et al. (1976). E Mesostygarctus, redrawn from Hansen et al. (2012). F Pseudostygarctus, redrawn from McKirdy et al. (1976). G Prostygarctus, original drawing. H Parastygarctus, redrawn from McKirdy et al. (1976). I Neostygarctus, Fujimoto & Miyazaki (2013).