Hypsibius cf. scabropygus Cuenot , 1929

Zawierucha, Krzysztof, Dziamiecki, Jakub, Jakubowska, Natalia, Michalczyk, Lukasz & Kaczmarek, Lukasz, 2014, New tardigrade records for the Baltic states with a description of Minibiotus formosus sp. n. (Eutardigrada, Macrobiotidae), ZooKeys 408, pp. 81-105 : 86-88

Hypsibius cf. scabropygus Cuenot, 1929 Table 1, Figs 1-7

Localities and specimen numbers.

XI: 1 simplex, XII: 1 specimen, XIV: 34 specimens (including 4 simplexes), XV: 24 specimens (including 6 simplexes).

Description

(measurements in Table 1). Adults. Body transparent/white (after preparation), eyes present in 6 of 15 (40%) specimens mounted in Hoyer’s medium (Fig. 1). Dorsal cuticle sculptured: from head to legs II without tubercles but clearly thickened, from legs II to the caudal end of the body (including legs IV) with irregular tubercles and platelets. Tubercles increasing in size from the anterior to the posterior part of the body, reaching maximum dimensions between legs III and IV, where tubercles sometimes merge and form irregular platelets (Figs 2-5). Irregular tubercles 1.0-6.0 μm in diameter. Ventral cuticle smooth (i.e. without sculpturing). Gibbosities and cuticular pores absent.

Bucco-pharyngeal apparatus of the Hypsibius type, without the ventral lamina, and with forked apophyses for stylet muscles (Fig. 6). Peribuccal lamellae absent. Teeth in the oral cavity armature absent or not visible under PCM. Pharyngeal bulb with apophyses and with two granular macroplacoids (both, without constrictions). Macroplacoid length sequence 2<1. Microplacoid and septulum absent.

Claws of the Hypsibius type, internal claws much smaller and of a different shape than the external claws (Fig. 7). All main branches with large accessory points. Smooth, indistinct areoles under claws usually visible only on posterior claws IV. Cuticular bars under claws I-III absent but a small bar is present near the posterior claw IV (Fig. 7, arrow).

Eggs. Unknown.

Remarks.

Hypsibius scabropygus has been recorded from many localities, mostly in the Holarctic ( McInnes 1994). In general, our specimens correspond to the original description by Cuénot (1929, 1932) and later descriptions by Marcus (1930) (= Hypsibius callimerus spec. nov.), and by Ramazzotti and Maucci (1983). However, importantly, none of the above mentioned descriptions reported a bar between anterior and posterior claws IV, which is present in all our specimens. Given the bar is small, it is possible that it was overlooked by Cuénot and later authors. If, however, Hypsibius scabropygus does not have the bar, then our specimens should probably be classified as a new species. Thus, until Hypsibius scabropygus is redescribed, our Latvian and Estonian records should be regarded as Hypsibius cf. scabropygus. As there is a possibility of our specimens belonging to a new species, we provide standard morphometrics (Table 1) and photographs (Figs 1-7).