Polycarpon tetraphyllum subsp. diphyllum (Cav.) O. Bolòs & Font Quer

Raab-Straube, Eckhard von & Raus, Thomas, 2022, Euro + Med-Checklist Notulae, 15, Willdenowia 52 (2), pp. 273-299 : 278

Polycarpon tetraphyllum subsp. diphyllum (Cav.) O. Bolòs & Font Quer

+ Tu(A): Turkey: Samsun province, Atakum, Cumhuriyet district, roadside, 7 Jun 2021, Karaer 2021-01 (OMUB); ibid., Karaer 2021-02 (OMUB); Samsun province, Ilkadım, Cumhuriyet Sarayı, roadside, 29 Mar 2022, Karaer 2022-15 (NGBB, OMUB). – Marhold (2011a +) reported Polycarpon tetraphyllum subsp. diphyllum only in the European part of Turkey, based on Greuter & al. (1984) and Chater & Akeroyd (1993), whereas both Jalas & Suominen (1983: 156) and POWO (2022g) did not record it in European Turkey. Concerning Asiatic Turkey ( Anatolia), no data about the occurrence of this taxon were found by us. Güner & al. (2012) refrained from mentioning infraspecific taxa of P. tetraphyllum (L.) L. for any Turkish area. Furthermore, our discovery seems to be the first one for Asia (see, e.g., POWO 2022g). The five populations found (four in Atakum district and another far from there in Ilkadım district) cover an area of 5–10 km 2 (each with 150–300 individuals) and are in good condition. Polycarpon tetraphyllum subsp. diphyllum is a roadside plant typically adapted to urban habitats. According to the current taxonomic concept (see, e.g., Kool & al. 2007; Iamonico & Domina 2015), the genus Polycarpon is monotypic including P. tetraphyllum with eleven subspecies, mostly native to the Mediterranean area and SW Asia; few taxa have a restricted distribution, e.g. P. tetraphyllum subsp. depressum (Nutt.) Iamonico from California ( U.S.A.) and Baja California ( Mexico) (see Iamonico 2015b) and P. tetraphyllum subsp. apurense (Kunth) Iamonico & Zanotti from a few places of Argentina, Colombia, Paraguay and Venezuela (see Iamonico & Zanotti 2022). The various subspecies differ from each other by both vegetative and sexual characters (a comprehensive taxonomic revision is in preparation by D.I.). Among the diagnostic characters is the arrangement of the leaves. The plants found in Samsun (C Black Sea region) have upper leaves in whorls of 4, whereas the lower leaves are opposite. Only three subspecies display this configuration, i.e. P. tetraphyllum subsp. colomense (Porta) Iamonico & Domina , P. tetraphyllum subsp. herniarioides (Ball.) Iamonico & Domina and P. tetraphyllum subsp. diphyllum . The latter taxon differs from the two former ones mainly by its habit (annual vs perennial), inflorescence (dense vs lax) and number of stamens (3 or 4 vs 5); P. tetraphyllum subsp. herniarioides also differs by the height of the plant (up to 6 cm vs 5–10 cm in P. tetraphyllum subsp. diphyllum and P. tetraphyllum subsp. colomense ), the width of the leaves (1–2.5 mm vs 2–6 mm) and their thickness (fleshy vs not fleshy).

D. Iamonico, F. Karaer & M. Keskin