Chaetonotus (Hystricochaetonotus) macrochaetus Zelinka, 1889

Trokhymchuk, R. R., 2020, New Reports Of Gastrotricha For The North-Eastern Ukraine, Zoodiversity 54 (5), pp. 349-356 : 352-353

Chaetonotus (Hystricochaetonotus) macrochaetus Zelinka, 1889 ( fig. 2 , C)

Material. 2 specimens. TL 170–177 µm, aL 12 µm, pL 43–45 µm, md 8–9 µm, hw 41 µm, nw 35–37 µm, tw 18–19 µm.

Description.The morphology and the dimensions of the animals collected correspond to the literature data ( Schwank, 1990). Stocky body. Head rounded to weakly five-lobed with two pairs of cephalic sensory ciliary tufts. Cephalion and pleurae weakly developed. Hypostomium present. Two pairs of dorsal sensory bristles. Dorsal surface covered by three-lobed scales with barbed spines. In the mid-trunk region both scales and spines suddenly increase in length. Posterior trunk region with three-lobed scales that lack spines. Ventrolateral scales and spines similar to those of dorsal surface but smaller in size. A pair of keeled ventral terminal scales with short spines present. Interciliary area covered by rounded usually keeled scales. Mouth subterminal.

D i s t r i b u t i o n a n d e c o l o g y. Cosmopolitic species ( Balsamo et al., 2008). Reported from Europe: Austria, Bulgaria, Denmark, Estonia, Germany, Great Britain, Hungary, Italy, Poland, Romania, Russia, Switzerland, Sweden, Brasil, Canada, Israel ( Kånneby, 2011). Typical periphytyc species for olygo- and mesosaprobic water bodies ( Sladeček, 1976).

Remarks. More than century ago this species is reported from Ukrainian Carpathians ( Jakubski, 1919). This species is reported in Kharkiv Region for the first time.

Subgenus Zonochaeta Remane, 1927

Chaetonotus (Zonochaeta) bisacer Greuter, 1917 ( fig. 3 , A)

Material. 1 specimen. TL 209 µm, aL 13 µm, pL 33,4 µm, md 5 µm, hw 30.8 µm, nw 29 µm, tw 15,7 µm.

D e s c r i p t i o n. The morphology and the dimensions of the animal collected correspond to the literature data ( Schwank, 1990). Slender body. Head five-lobed with two pairs of cephalic sensory ciliary tufts. Cephalion and pleurae well developed. Hypostomium developed. Two pairs of dorsal sensory bristles. Anterior to the spine girdle the dorsal surface is covered by elongated weakly threelobed scales with very short simple spines. A pair of longer terminal spines. A pair of long parafurcal spines. Interciliary field covered by small elongated keeled scales. Mouth subterminal. Pharynx with anterior and posterior swellings, the posterior larger than the anterior.

D i s t r i b u t i o n a n d e c o l o g y. Cosmopolitic species ( Balsamo et al., 2008). Reported from Europe: Denmark, Germany, Great Britain, Italy, Poland, Romania, Russia, Switzerland; Argentina, Brazil, Canada, USA, Japan, Corea ( Kånneby, 2011).

Remarks. This species is reported in Ukraine for the first time.

Subgenus Primochaetus Kisielewski, 1997

Chaetonotus (Primochaetus) heideri Brehm, 1917 ( fig. 3 , B)

Material: 1 specimen. TL 217 µm, aL 18 µm, pL 55 µm, md 12 µm.

D e s c r i p t i o n. The morphology and the dimensions of the animal collected correspond to the literature data ( Schwank, 1990). Head rounded to weakly five-lobed with two pairs of cephalic sensory ciliary tufts. Cephalion and pleurae weakly developed. Two pairs of dorsal sensory bristles. Furca relatively short. Dorsal surface covered with heart-shaped to pentagonal scales, sometimes with more or less well developed double anterior edge. Scales increase in size from the head region to mid-posterior trunk region with a subsequent decrease towards the caudal end. Barbed spines originate from approximately the center of each scale, increasing in length from anterior to posterior. The posteriormost spines can overshoot the furca. The medial spines can be longer than the furca. Mouth large.

D i s t r i b u t i o n a n d e c o l o g y. Cosmopolitic species ( Balsamo et al., 2008). Reported from Europe: France, Germany, Great Britain, Italy, Poland, Romania, Russia, Sweden; Brazil, Canada and USA ( Kånneby, 2011). Remarks. This species is reported in Ukraine for the first time.

Figures

Fig. 2. Gastrotrichs of the Karyakiv ravine pond: A — Chaetonotus (Chaetonotus) maximus; B — Chaetonotus (Hystricochaetonotus) hystrix; C — Chaetonotus (Hystricochaetonotus) macrochaetus. Scale bars 30 µm.

Fig. 3. Gastrotrichs of the Karyakiv ravine pond: A — Chaetonotus (Zonochaeta) bisacer, B — Chaetonotus (Primochaetus) heideri, C — Lepidodermella minor minor, D — Lepidodermella squamata, E — Ichthydium maximum, F — Haltidytes festinans. Scale bars 30 µm.