Baltalimania, AX, 1959 AND

Atherton, Sarah & Jondelius, Ulf, 2022, Phylogenetic assessment and systematic revision of the acoel family Isodiametridae, Zoological Journal of the Linnean Society 194, pp. 736-760 : 745

SYNONYMIZATION OF BALTALIMANIA AX, 1959 AND ARCHAPHANOSTOMA DÖRJES, 1968

Dörjes (1968) placed the three species of Baltalimania of the time into different genera, based solely on the presence or absence of a female bursa. Archaphanostoma was created to encompass two species [ A. agile ( Jensen, 1878) and A. macrospiriferum ( Westblad, 1946) ] with bursal tissue, leaving the one species that lacked bursal tissue ( B. kosswigi Dörjes, 1968 ) to comprise its own monotypic genus. Subsequently and without mention of Baltalimania, Kånneby et al. (2014) amended the diagnosis of Archaphanostoma to include both species with and without bursal tissue, following phylogenetic analysis of nucleotide sequences from three genes that demonstrated that four new species without bursa ( A. fontaneti Kånneby et al., 2015 ; A. occulta Kånneby et al., 2015 ; A. sublitorialis Kånneby et al., 2015 and A. ylvae Kånneby et al., 2015 ) nested within the Archaphanostoma clade. Unfortunately, the amended diagnosis caused Baltalimania and Archaphanstoma to be morphologically indistinguishable. Phylogenetic analyses oppose Dörjes’ (1968) argument that bursal tissue is a good character to differentiate these genera ( Figs 1 , 5 ). Although no DNA sequences currently exist for B. kosswigi , the identical generic diagnoses and similarities in the morphologies of B. kosswigi and species of Archaphanostoma without bursal tissue strongly suggest that the two genera are synonymous. Therefore, Archaphanostoma is a junior synonym for Baltalimania .

Figures

Figure 1. Concatenated 28S, 18S and COI gene tree summary. Percent bootstrap values are given at each node. Sequences from six species of Isodiametridae and Actinoposthiidae represented only by 18S sequences downloaded from GenBank (Table S1) were excluded.

Figure 5. Bursal morphology of Isodiametridae mapped onto the concatenated tree. The bursal morphology of each species was coded following original descriptions and illustrations, as well as photos and live observation of species where possible.