Is Phoronis embryolabi Temereva et Chichvarkhin, 2016 a true new species?

The first task would have been to compare individuals identified as “true” Phoronis pallida with those assumed to be P. embryolabi. Temereva & Chichvarkhin (2017) mention in their study only two specimens [1], attributed to the latter species, sampled in Vostok Bay, about 80 km east of Vladivostok (Russia), in a tube of Axiid shrimp Nihonotrypaea japonica in Vostok Bay (Sea of Japan, Russia) [see also Santagata, 2004]. In order to identify a species, 10 to 20 specimens are necessary to avoid misinterpretation of characters variations (Emig, 2017a, 2017b). Such examples exist in description of new species, including individuals in regeneration, i.e., Temereva (2000) and Temereva & Malakhov (1999).

Comparing the description of the characters assigned to P. embryolabi with the diagnosis of P. pallida (Emig, 1987; Viéitez et a.l, 1987; Emig et al., 2005; Emig, 2017b), one can easily confirm the sentence written by Temereva & Chichvarkhin (2017, p. 65): “P. embryolabi among phoronids is extremely (sic) similar to that of Phoronis pallida.” According to these latter authors, the only distinctive character appears be in metanephridia, although the arrangement is identical including the two pseudo-funnels, the anal slightly larger than the oral, as described for P. pallida by Viéitez et al. (1987). In addition, it has been well described previously that metanephridial tissues may evolve during lifetime to reach the most developed form during the breeding season. In juvenile individuals, nephridia may have pseudo-funnels that are often difficult to be distinguished, while mature specimens develop strong epithelia around funnels [see also Phoronopsis harmeri].

Two apomorphic characters of P. pallida are unique among the phoronid species, i.e., the presence of three circular sphincters in the trunk, and peculiar longitudinal muscle bundles, well studied by Silén (1952), Emig (1987), Viéitez et al. (1987), Emig et al. (2005). The muscle formulae in P. pallida are not always easy to be established according the variations of the arrangement of muscle bundles. However these formulae are not a taxonomic character because related to the size of an individual (Emig, 1985); nevertheless P. pallida seems be an exception with a rather constant number of muscle bundles. P. embryolabi shares the same characters and arrangement, but misinterpretation is reported by Temereva & Chichvarkhin (2017, p. 75): “...and the bundles can not be strictly distinguished. The approximate muscle formula is...”

Thus, according to the diagnosis and the cladistic analysis (Emig, 1985, 2017b, based on more than a hundred specimens), the synonymy with P. pallida is not surprising, and confirmed by the analysis of cytochrome oxidase (or IOC) with the unique position of this species within the Phoronida, even without the analysis of P. pallida by Temereva & Chichvarkhin (2017: Table 5). It should be noted that these authors themselves indicate: “according to analysis of 28s rRNA, P. embryolabi is close to Phoronis pallida.” This statement informs on the limit of molecular analyses compared to cladistics one in systematics within a genus, here Phoronis!

Obviously, apomorphic characters of P. pallida cannot be shared by a new species, except if this latter is considered as synonymous. Consequently, a new cladistic analysis leading to new hypotheses has to be done to avoid any falsification (sensu cladistics definition) and the establishment of a true phylogenetic diagnose [1].

About “viviparity” [2] observed in one or two individuals, one must be emphasized that the species is hermaphroditic and fertilization in phoronids may be internal: a study on this possible ovoviviparity should be carried out on a large number of individuals, to be conclusive. It may also appear tp be an abnormal embryonic development under conditions that must be established and explained. Radioactive pollution along the coasts around Vladivostok (OECD/OCDE, 1999) must surely be taken into account as a possible cause. It should also be noted that abnormal embryonic and larval developments have already been described in other phoronid species.

In conclusion, Phoronis embryolabi is considered as a synonym of Phoronis pallida (Schneider, 1862) until a cladistic analysis, based on the study of at least 10-20 specimens (see Emig, 1985). Note that individuals used for molecular analysis are identified on morphological taxonomic characters. For example, in their tables and figures, Temereva & Chichvarkhin (2016) mention synonyms besides valid species, i.e., Phoronis vancouverensis instead of P. ijimai, P. architecta instead of P. psammophila, Phoronospsis viridis instead of Phoronopsis harmeri, and probably Phoronis embryolabi instead of P. pallida.

[1] Contrary to the art. 13A. and 16.4.2 of the Code (ICZN, 1999), a diagnosis of the new species is lacking. In a section called “differential diagnosis” (Temereva & Chichvarkhin, 2017), the first sentence is “Phoronis embryolabi sp. nov. is most similar to Phoronis pallida Silén, 1952”, while a diagnosis of the phylogenetic characters should be given to allow identifying a species from all others of the same genus.

[2] The correct term is ovoviviparity.

[3] The Phoronida website, like that of Phoronida database, have online the nearly exhaustive bibliography on Phoronida, that should make impossible to avoid previous publications, i.e., before 2017 on P. pallida!