Mycoheterotrophic Plants

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Oxygyne shinzatoi (Hatusima) Tsukaya 2016

Hatusima (1975) published a "Flora of the Ryukyus" in Japanese language, including the description of a new genus Saionia comprising the species Saionia shinzatoi. This description came without a latin diagnosis, required by the International Code of Nomenclature for algae, fungi, and plants (ICN), therefore being invalid. Hence, Hatusima (1976) provided a publication in English, including the latin diagnosis, but now he designated two holotypes. Again, this made the description invalid according to the rules of the ICN. Abe & Akasawa (1989), unaware of the formal mistake of Hatusima (1976), found another species closely related to the genus Oxygyne (O. triandra from Africa) and Saionia (S. shinzatoi from Japan), and concluded these three species to be a single genus, Oxygyne. Nevertheless, their transfer of Saionia shinzatoi to Oxygyne shinzatoi was invalid as well, because the assumed basionym was not validly published ). Ohashi (2015), aware of the incorrect description of Hatusima (1976), designated a lectotype of 'Saionia shinzatoi Hatusima' in order to rectify the matter (see Cheek et al. 2018). And even the eventual legal tranfer of that type specimen to Oxygyne shinzatoi by Tsukaya (2016) in the Flora of Japan was not without flaws, because he named it "Oxygyne shinzatoi (H. Ohashi) Tsukaya" instead of "Oxygyne shinzatoi (Hatusima) Tsukaya", as pointed out by Suetsugu et al. 2019).
Ohashi (2015) intended to keep the genus Saionia vs. Oxygyne for differences in shape and colour of the perianth, direction of the corolla lobes, presence or not of stylar appendages beneath the stigma, and not at least because of the geographical distance between African and Japan. However, at the latest when Cheek et al. (2018) described Oxygyne duncanii from Cameroon, showing stylar appendages, the campanulate shape of the corolla tube, and the patent orienation of the corolla lobes like the Japanese species, the distinction between the two genera became vague. Eventually, the formal transfer of Saionia shinzatoi to Oxygyne shinzatoi was undertaken by Tsukaya (2016) in the Flora of Japan. However, being another flaw in a row of formal mistakes attributed to this species, Tsukaya named the type specimen 'Oxygyne shinzatoi (H. Ohashi) Tsukaya' instead of 'Oxygyne shinzatoi (Hatusima) Tsukaya', which offends ICN Art. 46.3. Note. 4., as pointed out by Suetsugu et al. (2019).
Corroborating the unity of Japanese and African species of Oxygyne, Suetsugu et al (2019) found remarkable morphological variation of O. shinzatoi within a radius of about 13 km around its type locality. The variations concern coloration, lamellae structure as well as the angle of the protruding angle of the perianth lobes.

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