Chaetonotus (Hystricochaetonotus) gulosus

Reference

Rataj Križanová F. & Vďačný P. (2022) A huge undescribed diversity of the subgenus Hystricochaetonotus (Gastrotricha, Chaetonotidae, Chaetonotus) in Central Europe. European Journal of Taxonomy 840: 1-93. https://doi.org/10.5852/ejt.2022.840.1941

Chaetonotus (Hystricochaetonotus) gulosus, schematic drawings. (A) Dorsal overview showing the scale and spine pattern. (B) Ventral overview showing the scale and ciliary pattern. Scale bar: 30 μm.

Chaetonotus (Hystricochaetonotus) gulosus sp. nov., schematic drawings of scales. (A) Head scale. (B) Neck scale. (C) Dorsal trunk scales. (D–E) Dorsolateral and lateral trunk scales. (F) Ventrolateral trunk scales. (G) Posteriormost ventral trunk scales. (H) Scales of the ventral interciliary field. (I) Ventral furcal scales.

Secondary structure of the 18S rRNA molecule of Chaetonotus (Hystricochaetonotus) gulosus. The single diagnostic molecular autapomorphy is situated in helix 39es9 (red arrow). The reference 18S secondary structure map of Saccharomyces cerevisiae (inset) is from apollo.chemistry.gatech.edu/RibosomeGallery.

Secondary structure of the first two domains of the 28S rRNA molecule of Chaetonotus (Hystricochaetonotus) gulosus. The single diagnostic molecular autapomorphy is situated in helix 25es7a (red arrow). The reference 28S secondary structure map of Saccharomyces cerevisiae (inset) is from apollo.chemistry.gatech.edu/RibosomeGallery.

Morphological diagnosis

ody stocky and around 107 μm long. Head wider than neck, separated from trunk by a distinct neck constriction. Cephalion and epipleurae clearly demarcated, hypopleurae only inconspicuously marked. Trunk widest at ca U50, gradually tapers towards furca base (U80). Mouth ventral, no cuticular teeth. Hypostomium bears two parallel cuticular lamellae. Pharynx without dilatations. Intestine straight, with a marked anterior section. Scales spined, three-lobed, not overlapping, distributed in 14 columns, 12 scales per column. Scales and spines increase gradually in size in a posterior direction. Dorsal surface covered with: (i) small head and anterior neck scales with a small, broadly rounded anterior lobe, equally long posterior lobes, and marked transition between anterior and posterior lobes; (ii) small posterior neck scales with a slightly elongated anterior lobe and an indistinct transition between anterior and posterior lobes; and (iii) comparatively big and triangular trunk scales. Interciliary field covered by (i) small, oval to oblong scales without keels; (ii) a pair of small, oval scales with a keel; (iii) a single distinctly bigger, oblong, and keeled scale; and (iv) a pair of big, very narrowly ovate, and spined scales. Furca branches about as long as adhesive tubes, with lateral margins more or less straight, furcal indentation shallowly U-shaped, adhesive tubes well-developed. Ventral side of furca branches covered with minute, oval to oblong, and keeled scales.

Molecular diagnosis

18S rRNA gene: 1378 A. ITS2: 78 T, 128 T, 155 ‒, 172 A, 174 C, 186 ‒.

28S rRNA gene: 503 C.

Cytochrome c oxidase subunit I (codon ordinal numbers are followed by the corresponding span of nucleotide positions in parentheses): 20 (58‒60) TTA, 45 (133‒135) GTG, 71 (211‒213) CCG, 74 (220‒222) ATC, 94 (280‒282) CCA, 143 (427‒429) TCA, 151 (451‒453) TTC, 157 (469‒471) AAT, 168 (502‒504) CTC, 178 (532‒534) ACT, 180 (538‒540) GTT, 204 (610‒612) ACA, 209 (625‒627) CCA, 214 (640‒642) GAT.

Type material

A DNA sample of the holotype specimen VP 18 has been deposited in the Natural History Museum, Vajanského nábrežie 2, 810 06 Bratislava, Slovakia (ID Collection Code 01427574).

Type locality

Vajspeterský potok creek, Rača, Bratislava, Podunajská rovina plain, Slovakia, 48°12′12.8″ N, 17°07′46.9″ E.