Najas marina subsp. armata Horn

Troia, Angelo, 2022, The unnoticed northward expansion of Najas marina subsp. armata (Hydrocharitaceae) in the Mediterranean area: an effect of climate change?, Willdenowia 52 (1), pp. 91-101 : 92-93

Najas marina subsp. armata Horn in Kew Bull. 7: 29. 1952

≡ Najas muricata Delile, Descr. Egypte, Hist. Nat.: 281. 1813, nom. illeg. [non Najas muricata Thuill., Fl.

Env. Paris, ed. 2: 509. 1799]

≡ Najas delilei Rouy in Rouy & Foucaud, Fl. France 13: 294. 1912

≡ Najas armata H. Lindb. in Acta Soc. Sci. Fenn., Ser. B, Opera Biol. 1(2): 8. 1932, nom. illeg.

≡ Najas marina var. delilei (Rouy) Maire, Fl. Afrique N. 1: 205. 1952. – Protologue citation: “au bord d’un lac d’eau saumâtre avec le Zannichellia palustris , près de Fâreskour, dans la basse Égypte ”.

– Lectotype (designated by Triest 1987: 29): Egypt, Delile in Herb. Delile ( MPU 007340 [image!]) . – Notes: the type was indicated as “ holotype ” by Triest (l.c.), to be corrected to lectotype ( McNeill 2014) under Art. 9.10 of the Code ( Turland & al. 2018). I was unable to find duplicates of MPU 007340 or other relevant specimens, but the illustration published as part of the protologue is another element of original material (Art. 9.4(b)). Both N. delilei and N. armata are replacement names for N. muricata Delile , which is a later homonym of N. muricata Thuill. and therefore illegitimate (Art. 53.1); N. armata was nomenclaturally superfluous when published and is therefore illegitimate (Art. 52.1); consequently N. marina subsp. armata is not a new combination but rather a replacement name (Art. 58.1).

Najas marina subsp. armata is the name and rank adopted by Triest in his revisions of the genus Najas in Africa ( Triest 1987) and the Old World (Triest 1988). Before him, the taxon was variously treated: as a variety ( Rendle 1899; Fiori 1923; Maire 1952; Cirujano & Lopez Alberca 1984), subspecies (Horn af Rantzien 1952) or species ( Delile 1813 –1814; Braun 1864; Rouy 1912; Lindberg 1932; Taeckholm & Drar 1941). After Triest, the taxon has been generally accepted at infraspecific rank ( Uotila 2009), sometimes doubtfully ( Pignatti 1982; Bartolucci & al. 2018), but sometimes it was merged with N. marina subsp. intermedia ( POWO 2022) or not mentioned at all ( Pignatti & al. 2017). Rarely it is accepted as a separate species, and in that case the correct name is N. delilei ( Feinbrun-Dothan 1991) .

Najas marina subsp. armata is a well-separated taxon and, according to the available knowledge, subspecific rank seems to be the most appropriate. Diagnostic characters were already identified by Triest (1988, 1989), but they are summarized below in a new key also to update the nomenclature (with seed length measurements modified according to Rüegg & al. 2019).

1. Seeds (3.3–)4–6(–7.5) mm long; ovary (3–)4–6 × 2–2.5 mm; style and stigma 2–3 mm long; anther 3.8–4 mm long................... Najas major

– Seeds 2.5–4(–5.1) mm long; ovary 0.7–3.4 × 0.4– 1.7 mm; style and stigma 0.2–1.4 mm long; anther 1–3.3 mm long............................ 2

2. Stems and back of midrib not very spiny, (0–)2–10 (–15) spines in 2 cm; seeds 3.7–4.3 mm long....................... Najas marina subsp. marina

– Stems and back of midrib very spiny, (10–)15–30 (–50) spines in 2 cm; seeds 2.5–3.5 mm long....................... Najas marina subsp. armata

Najas marina subsp. armata seems to differ from subsp. marina also in ecology (see below) and distribution. They are allopatric: subsp. marina is restricted to cold and temperate areas from Europe to C Asia, whereas subsp. armata is distributed in tropical and subtropical Africa, Sri Lanka (but see Silva & al. 2020) and Australia (Triest 1988). The only critical area seems to be in Turkey, where it is difficult to separate the two taxa (Triest 1988: 64; Triest & Uotila 1988).

It is interesting to report that, in addition to being eaten by wild birds such as waterfowl (Aves: Anatidae) (Les 2020), in Egypt Najas marina subsp. armata is collected and dried to be used as fodder for sheep and goats (Yousif & al. 2020).