Chaetonotus (Chaetonotus) maximus Ehrenberg, 1838

Trokhymchuk, R. R., 2020, New Reports Of Gastrotricha For The North-Eastern Ukraine, Zoodiversity 54 (5), pp. 349-356 : 350-351

Chaetonotus (Chaetonotus) maximus Ehrenberg, 1838 ( fig. 2 , A)

M a t e r i a l. 7 specimens. TL 185–188 µm, aL 14 µm pL 44–46 µm, md 8 µm, hw 35–37 µm, nw 28–30 µm, tw 28–30 µm.

D e s c r i p t i o n. The morphology and the dimensions of the animals collected correspond to the literature data ( Schwank, 1990). Slender body. Five-lobed head with two pairs of cephalic sensory ciliary tufts. Large cephalion, epi- and hypopleurae. Hypostomium developed. Two pairs of dorsal sensory bristles present. Dorsal body surface covered by arrowhead-shaped three-lobed scales. In the head and neck regions the proximal parts of the scales are more rounded than in the trunk region. Scales bear simple spines that increase in length from anterior to posterior. Five stout spines present on the base of the furcal branches and at the caudal incision. One to two pairs of thick parafurcal spines. Ventrolateral scales and spines similar to those of the dorsal surface. Ventral interciliary field with transverse scale plates in the pharynx region. 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). Report- ed from Europe: Austria, Belgium, Bulgaria, Czech Republic, Denmark, Estonia, France, Germany, Great Britain, Hungary, Iceland, Italy, Poland, Romania, Russia, Spain, Sweden, Switzerland; Algeria, Canada, Japan, New Guinea and USA ( Kånneby, 2011). Long time ago the species was reported from Ukrainian Carpathians ( Jakubski, 1919). This species usually reported from olygosaprobic water bodies but also is common from all types of saprobity ( Sladeček, 1976).

Remarks.This species is reported in Kharkiv Region for the first time.

Subgenus Hystricochaetonotus Schwank, 1990

Chaetonotus (Hystricochaetonotus) hystrix Metschnikoff, 1865 ( fig. 2 , B)

M a t e r i a l. 2 specimens. TL 160–171 µm, aL 15 µm.

D e s c r i p t i o n. The morphology and the dimensions of the animals collected correspond to the literature data ( Schwank, 1990). Stout body. Head weakly five-lobed with two pairs of cephalic sensory ciliary tufts. Cephalion and pleurae weakly developed. Hypostomium absent. Two pairs of dorsal sensory bristles present. Dorsal body surface covered by three-lobed scales with deep posterior incision. Scales with barbed spines that increase in size towards the posterior end. An area of the dorsal posterior trunk region with scales that lack spines. Two pairs of thicker parafurcal spines present. Ventrolateral areas with scales with barbed spines, similar in shape to those of the dorsal surface but finer. Mouth subterminal.

Distribution and ecology. Cosmopolitic species ( Balsamo et al., 2008). Reported from Europe: Austria, Bulgaria, Denmark, Estonia, France, Great Britain, Hungary, Poland, Romania, Russia, Sweden; Brazil, Israel, Paraguay ( Kånneby, 2011). Epibentic and periphytyc species.

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.