Borisanova A.O.*, Ekimova I.A. 2025. The position of Urnatella gracilis Leidy, 1852 on the molecular phylogenetic tree changes the view on the systematics of colonial Entoprocta // Invert. Zool. Vol.22. No.3: 428–438 [in English].
Lomonosov Moscow State University, Biological faculty, Department of Invertebrate Zoology, Leninskiye Gory, 1-12, Moscow 119991 Russia.
* Corresponding author
Anastasia Borisanova: borisanovaao@mail.ru ORCID https://orcid.org/0000-0002-9700-6446
Irina Ekimova: irenekimova@gmail.com ORCID https://orcid.org/0000-0002-1846-0780
doi: 10.15298/invertzool.22.3.04
ABSTRACT: In currently accepted system, the colonial Entoprocta are represented by three families: Barentsiidae, Loxokalypodidae, and Pedicellinidae. The two only known freshwater species, Urnatella gracilis Leidy, 1852 and Loxosomatoides sirindhornae Wood, 2005, are included in two different families, Barentsiidae and Pedicellinidae respectively. Although the available molecular data on colonial entoprocts are poor, they show that the current taxonomical system needs to be revised. The main aim of this study is to elucidate the phylogenetic position of the freshwater species Urnatella gracilis using molecular data that were obtained for this species for the first time. The material was collected in the Don River (Russia). The study is based on the molecular analyses of partial fragments of two genetic markers: 28S rRNA and 18S rRNA. According to the results of study, Urnatella gracilis forms a monophyletic clade with Barentsia benedeni (Foettinger, 1887) and Loxosomatoides sirindhornae. The close relationship of two freshwater species means that the colonization of fresh waters could have occurred within one family of Entoprocta but not independently in two families, Barentsiidae and Pedicellinidae, as it was suggested earlier. The type of organization of the colony of both Loxosomatoides and Urnatella may have evolved from the colonial ancestor similar to B. benedeni. Based on the results of phylogenetic analysis, we propose to exclude B. benedeni from the genus Barentsia and to assign it to the reinstalled genus Arthropodaria. We also propose to restore the family Urnatellidae with genera Arthropodaria, Loxosomatoides, and Urnatella.
KEY WORDS: Kamptozoa, taxonomy, phylogeny, 28S, 18S, colonization of fresh waters.