Arundo micrantha Lam.

Hardion, Laurent, Verlaque, Régine, Callmander, Martin W. & Vila, Bruno, 2012, Arundo micrantha Lam. (Poaceae), the correct name for Arundo mauritanica Desf. and Arundo mediterranea Danin, Candollea 67 (1), pp. 131-135 : 132-134

Arundo micrantha Lam. ,

Tabl. Encycl. 1: 196. 1791 ( Fig. 1 ).

Typus: “ Ex AFRICA ”: Desfontaines s.n. (holo-: P-LA [ P00564266 ]!; iso-: B [ W02223 ]!, G [ G00074067 ]!, K [ K000366972 ]!, MPU [ 015598 ]!, P [ P00307101 ]!) .

= Arundo mauritanica Desf. , Fl. Atlant. 1: 106. 1798 [non Poir., Voy. Barbarie 2: 104. 1789. Ξ Ampelodesmos mauritanicus (Poir.) Durand & Schinz ].

Typus: ALGERIA: “ Herbier de la Flore Atlantique ”, Desfontaines s.n. (holo-: P [ P00307101 ]!; iso-: B [W02223]!, G [ G000 74067 ]!, K [ K000366972 ]!, MPU [ 015598 ]!, P-LA [ P00564266 ]!).

= Arundo mediterranea Danin in Wildenowia 34: 362. 2004.

Typus: ISRAEL: Nahal Sorek , 8 km east of Gedera, 18.IX.2004, Danin s.n. (holo-: HUJ!; iso-: B [ 1001 822322 , 100182323 ]!, E [ 00205435 ]!, MARS [ 00007 , 00008 ]!).

Additional specimens examined. – FRANCE. Languedoc - Roussillon: Sainte Lucie , Requien s.n. ( MARS-Ardoino [ 00011 ]); Aude, Coteau à Sainte-Lucie , près de Narbonne, 21.IX.1818, Gautier s.n. ( G-DC); Sainte-Lucie , 19.V.1828, Requien s.n. ( G); In insula St Luciae , X.1829, Eudrefs s.n. ( P [ P03161112 , P03161120 ]); Ile Sainte-Lucie , près de Narbonne, 25.VIII.1864, Gautier s.n. ( MPU, P [ P03626575 ]); Ile Sainte-Lucie , 12.IX.1877, Bonneau s.n. ( MPU); Ile Sainte Lucie , près de Narbonne, molasse marine, 15 m, 27.IX.1882, Doumergue s.n. ( G, MARS [ 00012 ], MPU, P [ P02656180 , P02656198 , P03161077 , P03235090 , P03626594 ]); Sainte-Lucie , 1891, Requien s.n. ( MPU); Aude, Ile Sainte-Lucie , IX.1893, Jonas-Martyr s.n. ( G, MPU, P [ P02421019 , P02421020 , P02421021 , P03161074 , P03168006 , P03235087 , P03626559 , P03626580 ]); Ile Sainte-Lucie , IX.1893, Martin s.n. ( P [ P03626574 ]); Ile Sainte-Lucie , IX.1893 -94, Sevitien & Sevitien s.n. ( G, MPU, P [ P02421022 , P03161075 , P03235086 , P03242364 , P03242365 , P03235079 , P03626551 , P03626552 , P03626579 ]); Aude, Ile Sainte-Lucie , près de la station de chemin de fer , 20.II.1921, Neyraut s.n. ( MPU); Port-la-Nouvelle, Ile Sainte-Lucie , between the island and railway, ca. 2 m, 43°03’ 25”N 03°01’52”E, 5.VIII.2011, Hardion & al. s.n. ( MARS [ 00013 ], MARS [ 00014 ]). Provence-Alpes-Côte d’Azur: entre Cannes et Antibes, dans le Golfe de Juan , Gay s.n. ( MPU); Golfe de Juan, 24.IX.1821, Gay s.n. ( G); Route d’Antibes à Cannes, devant la villa “ Jean Reynaud ”, 10.X. 1868, Thuret s.n. ( G); Golfe-Juan, 28.X.1868, Moggridga s.n. ( P [ P03626544 ]); Golfe-Juan, bords des ravines, 31.X. 1868, Thuret s.n. ( G, P [ P03161108 ]); Golfe Juan, non loin de la gare, presque en face du Château Robert , 27.X.1874, Bernardin s.n. ( G, MPU, P [ P02420203 , P02656199 , P03161104 , P03626 558 ]); Golfe-Juan, 5.XI.1878, Consolat s.n. ( G); Golfe-Juan, XII.1904, Mader s.n. ( G); Vallauris Golfe-Juan, in beach back, between road and railway, ca. 4 m, 43°33’48”N 7°04’07”E, 21.IX.2011, Hardion & al. s.n. ( MARS [ 00015 ], MARS [ 00016 ]).

Morphology. – Our observations in the wild confirmed that A. micrantha is characterized by clearly branched stems, as previously emphasized by DESFONTAINES (1798) and DANIN (2004), coupled with a tussock habit and high culms (2-4 m) as described by DANIN (2004). However, these features are rarely present on herbarium specimens. On exsiccata, A. plinii complex (including A. micrantha ) differs from A. donax by its spikelets with 1- (2) vs 3-5 flowers as mentioned by LAMARCK (1791). Moreover, our study on many herbarium exsiccata (G, MARS, MPU, P) shows that A. micrantha differs from the rest of A. plinii complex by a larger culm diameter under the panicule (> 5 mm vs <4 mm). This new morphological character allows us to consider A. micrantha holotypus of Lamarck as conspecific with A. mauritanica Desf. and A. mediterranea Danin.

However, a broad morphological investigation coupled with a phylogenetic analysis on a Mediterranean sampling is needed to clarify the complex taxonomic delimitations in this genus. Because of many erroneous identifications in Herbarium exsiccata, this study will have to provide more discriminating characters, useful on vegetative as well as on reproductive material.

Ecology, distribution and conservation. – Notes on exsiccata labels gave us insights into the ecology of A. micrantha and its affinities with wetlands. This species mainly occurs on riverbanks and beach backs, in addition to ruderal sites. Because of its former synonymy under A. plinii s.l. and its resemblance to A. donax , the A. micrantha distribution was dramatically underestimated in the Mediterranean basin. Since 2004, it has been reported from Algeria, Crete, Cyprus, Greece, Lebanon, Morocco, Palestine and Rhodes ( DANIN, 2004; DOBIGNARD & CHATELAIN, 2010). The careful examination of several specimens of A. plinii s.l. (G, MARS, MPU and P) allowed us to rediscover and identify wild populations in Golfe-Juan (Provence-Alpes-Côte d’Azur) and Sainte-Lucie Island (Languedoc-Roussillon) as A. micrantha . This discover adds for the first time this species to the Flora of France, in addition to A. donax and A. plinii (sensu DANIN, 2004) from Fréjus-Saint-Raphaël. Our field observations of these restricted populations revealed their highly threatened status. In Golfe-Juan, two patches (10 m 2) subsist on the urban littoral of French Riviera, between the back beach road and the railway, endangered by a project to extend train rails. According to numerous exsiccata, the population of Sainte-Lucie Island was the most visited of the French localities. Already impacted by human activity in the 19 th century (as indicated on P [032 42232]), this population is now drastically reduced to 4 m 2, without flowering for at least three years. In addition, other localities of A. plinii s.l. as Salses-le-Château (Languedoc-Roussillon) and Saint-Tropez (Provence-Alpes-Côte d’Azur) respectively mentioned by GAUTIER (1912 -1913) and CAMUS & CAMUS (1912), have never been seen again. Armando plinii s.l. being protected at regional scale (Provence-Alpes-Côte d’Azur and Languedoc-Roussillon), A. micrantha must be included under this status. However, A. micrantha needs urgent specific protection on French territory and may be considered as Critically Endangered (CR A1a, c; C1; D) in France following IUCN Red List Categories and Criteria ( IUCN, 2001).

Figures

Fig. 1. – Holotypus of Arundo micrantha Lam. [DesFontaines s.n., P-LA] [© MNHN CRHST-CNRS. Reproduced with permission]