Figure 3. ITS2 in A Heterolepidoderma and Halichaetoderma gen. nov. (Gastrotricha: Chaetonotidae) riddle: integrative taxonomy and phylogeny of six new freshwater species from Central Europe

Figure 3. ITS2 molecule of the genera Heterolepidoderma and Halichaetoderma gen. nov. A, putative consensus secondary structure. The central loop radiates four helices. However, helix I could not be incorporated into the consensus 2D structure due to its very high variability in length and nucleotide composition (see Figure 2). By contrast, helix II was the most conservative having 9–11 pairs and invariably seven nucleotides in its terminal loop. Helix III was distinctly longer than helix II (32–55 nt vs. 25–31 nt). Although being more variable than helix II, helix III consistently displayed a motif 5'-UUGGG vs. YYYAA-3' at its base. Helix IV was the longest, had 52–112 ribonucleotides, and usually ran along helix II according to the 3D modelling. For localization of helix 10, which is made by the interaction of the 3ʹ-end of 5.8S and the 5ʹ-end of 28S, see Figure 4. B, two different views on the tertiary structure, showing that helices II and IV run in parallel. C, structure logos of helices II‒IV. The height of a base is proportional to its frequency in the multiple sequence alignment.