 |
| Cornechiniscus mystacinus Gąsiorek, 2022 |
Abstract
Cornechiniscus Maucci & Ramazzotti, 1981 is a species-poor heterotardigrade genus with peculiar, horn-shaped appendages A. It can be found in mosses and lichens growing on dusty soils on all continents except for Australasia and Antarctica, with presumably Central Asia as the main place of species radiation. A recent, COI and ITS-1-based phylogeny elucidated phylogenetic relationships between 5 out of 10 Cornechiniscus species, and aided the integrative description of C. imperfectus Gąsiorek & Michalczyk, 2020 from mountains of Northern Kyrgyzstan. However, the other 5 species remained unplaced on the generic evolutionary tree. Using new samples from Northern Kyrgyzstan, Italy and Argentina, I extracted new representatives of the genus and updated the genus phylogeny in the frame of integrated taxonomic approach (light and scanning microscopy, DNA sequencing of four markers: 18S rRNA, 28S rRNA, ITS-1, and COI). A new Kyrgyz species is dioecious and necessitates modifying the genus diagnosis to accommodate its cirri prolongation that contrasts with bulbous peribuccal cirri typical for Cornechiniscus. Furthermore, it enhances the hypothesis on the Central Asian origin of the genus. Morphologically, Cornechiniscus mystacinus sp. nov. most closely resembles C. tibetanus (Maucci, 1979) by its large body size (adult females ∼500 μm on average), strongly heteronych and smooth claws, and by the development of spines in the lateral positions C–E and at the posterior margin of the pseudosegmental plate IV’. I demonstrated the sister relationship between C. holmeni (Petersen, 1951) and C. imperfectus, previously hypothesised based on their morphological similarity. Cornechiniscus lobatus (Ramazzotti, 1943) can be considered a subcosmopolitan taxon since it certainly occurs in the Holarctic and Neotropics.
Keywords: Central Asia, Cephalic papilla, Cirri, Dioecious, Kyrgyzstan, Phylogeny
Phylum: Tardigrada Doyère, 1840
Class: Heterotardigrada Marcus, 1927.
Order: Echiniscoidea Richters, 1926.
Family: Echiniscidae Thulin, 1928.
Genus: Cornechiniscus Maucci & Ramazzotti, 1981.
Diagnosis (from Kristensen, 1987; amended): Echiniscids with black crystalline eyes, flexible buccal tube and pseudosegmental plate IV’. Appendages A horn-shaped. Secondary clavae (cephalic papillae) ovoid, domed; peribuccal cirri typically bulbous (onion-shaped), but exceptionally may be formed typically for the vast majority of echiniscids, i.e. with antenniform, flexible flagellum and well-delimited cirrophore.
 |
| Habitus of Cornechiniscus mystacinus sp. nov. (LM): A – adult female freshly mounted in Hoyer's medium (paratype in lateral view); B – cephalic body portion of another adult female just preserved on a permanent slide (paratype in dorsolateral view); C – adult female (holotype in dorsolateral view); D – adult male (allotype in dorsolateral view). Letters C–E signify lateral appendage positions. Scale bars in μm. |
Cornechiniscus mystacinus sp. nov.
Differential diagnosis: Cornechiniscus mystacinus sp. nov. is easily distinguishable from all congeners by the combination of the following characters: extreme elongation of peribuccal cirri (cirrus internus slightly longer than appendage A and cirrus externus several times longer than the latter; peribuccal cirri are typically bulbous in the genus, Fig. 7D) with tufted tips, granulation around the mouth cone and cephalic papillae, and the presence of males in populations. ...
Etymology: From Latin mystax = moustache. The name alludes to the significant prolongation of peribuccal cirri, especially of external ones, that calls to mind barbels of a catfish. An adjective in the nominative singular.
Piotr Gąsiorek. 2022. Water Bear with Barbels of A Catfish: A New Asian Cornechiniscus (Heterotardigrada: Echiniscidae) illuminates Evolution of the Genus. Zoologischer Anzeiger. In Press. DOI: 10.1016/j.jcz.2022.06.007
