Halichaetoderma Križanová & Vďačný 2024, gen. nov.
Creators: name: Križanová, Františka Rataj
name: Vďačný, Peter
Publisher: name: Zenodo
Year: 2023
Subjects: Biodiversity
Taxonomy
Animalia
Gastrotricha
Chaetonotida
Chaetonotidae
Halichaetoderma

description: Halichaetoderma gen. nov.
ZooBank registration: urn:lsid:zoobank.org:act: CC06AC83- F400-4AB1-9A8E-9742D710EFB7.
Diagnosis: Body tenpin-shaped and 88–120 µm long. Head distinctly five-lobed, cephalion, epipleurae, and hypopleurae well marked in the head outline. Two pairs of cephalic ciliary tufts. Mouth ring located ventroterminally, with well-developed rod-like reinforcements and none to three cuticular teeth. Pharynx with anterior and posterior dilatations, as well as with reinforcements. Dorsal, dorsolateral, lateral, and posterior ventral sides of body covered with comparatively small, oval to hexagonal, spineless scales with distinct keels. Scales located close to one another, mostly with overlapping edges. Number of dorsal alternating columns of scales distinctly higher than number of scales in central longitudinal column. Dorsal sensory bristles (setolae) absent or in up to three pairs, posteriormost pair on double-keeled, cordiform scales.Furca base clearly marked.Adhesive tubes thick and tapering toward distal end. Ventral intercilliary field almost naked or scaled. Dorsal upper-furcal region covered by comparatively large scales with keels. Ciliary bands enlarged anteriorly. Freshwater.
Molecular diagnosis: 18S rRNA gene: 649 T, 681 T, 684 A, 1263 C, 1492 A. 28S rRNA gene: 564 C, 804 C, 922 C, 950 C, 951 A, 952 G. COI (codon ordinal numbers are followed by the corresponding span of nucleotide positions in parentheses): 23 (67–69) TTA. All diagnostic molecular synapomorphies were mapped on the reference molecules of the type species, Halichaetoderma fluviatile sp. nov., and are marked by thin arrows.
Type species: Halichaetoderma fluviatile sp. nov. by original designation (Article 68.2 of ICZN 1999).
Etymology: A composite of the stem of the Ancient Greek adjective hálinos [ἅλῐνος (m), of salt], the thematic vowel · i-, the Greek noun khaítē [ΧΑίτη (f), flowing hair], and the Ancient Greek noun dérma [δέΡμᾰ (n), skin], referring to the morphological similarity to the genus Heterolepidoderma and close phylogenetic relatedness to the genus Halichaetonotus. Neuter gender.
Remarks: Morphological diagnostic characters of Halichaetoderma need to be placed in a phylogenetic context to recognize their apomorphic nature. Halichaetoderma does not have any obvious phenotypic autapomorphy with respect to Heterolepidoderma. This is caused by the homoplasious nature of cuticular features, as revealed by the present SIMMAP analyses (Figs 7–10) and by the very broad morphological definition of the latter genus (for further details, see: the ‘Discussion’ section). However, fromthephylogeneticpointofview, themorphological features used to define Halichaetoderma are autapomorphies with respect to Halichaetonotus, the sister-group of the new genus according to the present multi-gene phylogenies and the results of statistical topology testing. Thus, much smaller scales, a higher number of longitudinal rows of scales, the absence of higher and lamella-like keels and spined scales on the dorsal side, as well as the freshwater habitat, are autapomorphies of Halichaetoderma with respect to Halichaetonotus, while they are homoplasious apomorphies with respect to Heterolepidoderma. Finally, it is important to mention that Halichaetoderma is unambiguously defined molecularly and can be distinguished from Halichaetonotus and Heterolepidoderma by a combination of 12 molecular autapomorphies in the nuclear rDNA cistron and the mitochondrial COI gene.
description: Published as part of Križanová, Františka Rataj & Vďačný, Peter, 2024, A Heterolepidoderma and Halichaetoderma gen. nov. (Gastrotricha: Chaetonotidae) riddle: integrative taxonomy and phylogeny of six new freshwater species from Central Europe, pp. 283-335 in Zoological Journal of the Linnean Society 200 (2) on pages 312-315, DOI: 10.1093/zoolinnean/zlad079, http://zenodo.org/record/11240054