Chaetonotus (Primochaetus) armatus Kisielewski, 1981

Kånneby, Tobias, 2013, New species and records of freshwater Chaetonotus (Gastrotricha: Chaetonotidae) from Sweden, Zootaxa 3701 (5), pp. 551-588 : 575-576

Chaetonotus (Primochaetus) armatus Kisielewski, 1981

( Fig. 17 )

Localities: Lake Ånnsjön, Jämtland (N 63º 15’ 65’’; E 12º 27’ 03’’), July 8, 2008.

Material: 3 specimens.

TL, 143–196 µm; FL, 23–25 µm; AL, 17–18 µm; PhL, 45–50 µm; MD, 7–10 µm; TNC, 9–10; DC, 5–6; VLC, 4; HS, 6–7 x 12 µm; NS, 6–8 x 12 µm; DS, 14– 16 x 18–19 µm; HSp, 5–7 µm; NSp, 8–12 µm; DSp, 25–30 µm; VC, 6; VTS, 10–12 x NA µm.

Head squared to three-lobed with two pairs of cephalic sensory ciliary tufts. Cephalion and pleurae absent. Hypostomium well developed. At least the posterior pair of dorsal sensory bristles present in Swedish specimens. Furca straight with adhesive tubes constituting more than 2/3 of the total furca length. Dorsal surface with oval scales, always wider than long. All dorsal scales with barbed spines.

Ventrolateral scales and spines similar to those of the dorsal surface, but scales are often more rounded. On the head and neck region ventrolateral spines bear the barb at 2/3 of the total length in a distal direction. Ventral interciliary field covered by rounded to oval scales with simple spines. Ventral terminal scales keeled with long fine spines, up to 26 µm in length, overshooting the furcal branches.

Mouth subterminal. Pharynx widens towards the posterior end. PhIJ at U28–31. Intestine straight with anus at U83–85.

The Swedish specimens were all in parthenogenetic phase and fell within the ranges reported for Polish specimens (Kisielewski 1981). In contrast with literature data, the studied material showed that dorsal sensory bristles, at least the posterior pair, is present in C. (P.) armatus . Their anchor point could not be seen.

Previously reported from Poland (Kisielewski 1981) and Sweden (Kånneby et al. 2009; 2013).

Figures

FIGURE 17. Chaetonotus (P.) armatus. A) Ventral view of anterior body showing interciliary scales. B) Ventral view of midtrunk region showing interciliary scales. C) Dorsal view of mid-trunk region showing distribution of scales and spines. D) Dorsal view of anterior body showing distribution of scales and spines. Scale bars: 10 µm.