Noronhia broomeana Oliv.

Hong-Wa, Cynthia, Callmander, Martin W. & Baider, Cláudia, 2014, Taxonomy and conservation of the genus Noronhia Thouars (Oleaceae) in Mauritius, Candollea 69 (2), pp. 157-163 : 159

Noronhia broomeana Oliv. in Hooker’s Icon. Pl.: tab. 1365. 1881.

Ξ Linociera broomeana (Oliv.) Knobl. in Notizl. Bot. Gart. Berlin 11: 1028. 1934.

Ξ Chionanthus broomeana (Oliv.) A. J. Scott in Kew Bull. 33: 570. 1979.

Typus: MAURITIUS: The forests in the vicinity of Grand Bassin, 690 m, 16.III.1881, Horne s.n. (holo-: K [ K 000 233209]!; iso-: K [K000233208]!).

= Linociera verrucosa Soler. in Bot. Centralbl. 45: 399. 1891.

Ξ Mayepea verrucosa (Soler.) Knobl. in Engler & Prantl, Nat. Pflanzenfam. IV(2): 10. 1892. Typus: MAURITIUS: s.loc., s.d., Sieber [Fl. Mauritius II] 125 (holo-: M [ M0174392 ] image seen; iso-: E [ E00193 166 ] image seen; G [ G00008578 ]!, K [ K000233210 ]!, MO-2235287 !).

Observations. – Noronhia broomeana includes two varieties, both of which occur on Réunion Island: N. broomeana var. cordemoyana (Knobl.) Hong-Wa & Besnard and N. broomeana var. cyanocarpa (Cordem.) Hong-Wa & Besnard. The taxon occurring on Mauritius, the typical variety, N. broomeana var. broomeana , differs from these two by its much denser indumentum and its wider and larger leaves

COTT & GREEN, 1981) ( Fig. 1A ).

Conservation status. – Noronhia broomeana var. broomeana is the most commonly occurring member of the genus on Mauritius. The largest population occurs on Deux Mamelles Mountain (estimated to comprise 40-60 reproductive trees), with scattered individuals found at various wet locations at higher elevations (500-600 m). Deforestation and exploitation (trees provided good construction wood; Bouton in MAU [MAU 0014578]), were the main historical threats responsible for the decline of this taxon. Nowadays these factors are negligible ( FLORENS, 2013), although a site where N. broomeana var. broomeana is known to have occurred was cleared after 1940 (e.g. Bassin Anglais). There is only one known plant occurring at a lower elevation site (ca. 200 m, Rivulet Beau Bois), suggesting that this taxon was probably more widespread in the past. The “Extent of Occurrence” (EOO), calculated on the basis of the historically known populations, is 256 km 2 and the “Area of Occupancy” (AOO) is 32 km 2 (calculation following GEOCat version ss, see BACHAM & al., 2011) ( Fig. 2A ). However, at least one site (Bassin Anglais) is now destroyed, reducing the AOO by 13% (28 km 2), although the EOO has not decreased. There has been a reduction in the number of known locations, and therefore, of mature individuals. The total number of reproductive trees of N. broomeana var. broomeana is unknown but it is likely to be less than 150. All known reproductive trees are located on invaded forest sites, which are thus undergoing continuous habitat degradation. Apart from the reduced reproductive fitness, as explained above, the majority of fruits are depredated by alien rats, which is also the case for the other species of Noronhia on Mauritius (CB, pers. obs.). Species regeneration is consequently very low, with only a few seedlings recorded in the site where the majority of reproductive trees occur ( PAGE & D’ ARGENT, 1997). Noronhia broomeana var. broomeana should therefore be considered in Mauritius as “Endangered” [EN B1ab(ii,iii,iv,v); C2a(i,ii); D] according to the IUCN Red List Categories and Criteria ( IUCN, 2012). In Réunion, two varieties of N. broomeana present on the island were assessed together and have been classified as “Vulnerable” [VU C2a(i)] ( UICN-FRANCE & al., 2010).

Specimens examined. – MAURITIUS. Dist. Pamplemousses: Deux Mamelles , 16. I.2003, Pynee, d’Argent & Chitbauhaal s.n. ( MAU [ MAU 0014598 ]) ; ibid. loc., 20. V.2004, Pynee, Wiehe & Sevathian s.n. ( MAU [ MAU 0014599 ]) . Dist. Plaines Wilhems: Bassin Anglais , s.d., Vaughan V/583 A ( MAU [ MAU 0014588 ]) ; Garden in Curepipe , 30. V.1975, Coode [leg. Gerval] 4712 ( MAU [ MAU 0014596 ]) ; Mare Longue , 11. V.1946, Vaughan 3130 ( MAU [ MAU 0014590 ]) ; Rivulet Bérichon, Henrietta , 24. V.1974, Owadally s.n. ( MAU [ MAU 0014594 ]) . Dist. Savanne: Bassin Blanc , 550 m, 25. V.1976, Richardson, Guého & Lecordier 4165, ( K, MAU [ MAU 0014597 ]) ; Plaine Champagne , 18. I.1995, d’Argent & V. Florens s.n. ( MAU [ MAU 0014734 ]) ; Rivulet Bois Beau, near Rivière des Anguilles , 25. V.1964, Duljeet s.n. ( MAU [ MAU 0014592 ]) ; ibid. loc., 193 m, 20°27’57’’S 57°33’25’’E, 17. V. 2010, V. Florens & Baider CB 2367 ( MAU [ MAU 0015022 , MAU 0015023 , MAU 0015024 , MAU 0015025 , MAU 0015026 ]) . Sine loc.: s.d., Bouton s.n. ( MAU [ MAU 0014578 ]) ; s.d., Bijoux s.n. ( MAU [ MAU 0014579 , MAU 0014580 , MAU 0014581 , MAU 0014582 , MAU 0014583 , MAU 0014584 ]) , s.d., Vaughan 583 ( MAU [ MAU 0014587 ]) ; s.d., s. coll. ( MAU [ MAU 0014585 , MAU 0014586 ]).

Figures

Fig. 1. – Living plants of NoronHia Thouars on Mauritius. A. NoronHia broomeana Oliv. var. broomeana; B-C. Close-up of NoronHia macropHylla (Baker) Hong-Wa & Callm.; D. NoronHia obovata (Baker) Hong-Wa & Callm. [A: V. Florens & Baider CB 2367; B-C: Baider s.n., pers. obs.; D: Baider & V. Florens CB 2461] [Photos: A, D: V. Florens; B: C. Baider]

Fig. 2. – Distribution maps of NoronHia broomeana Oliv. var. broomeana (A), NoronHia macropHylla (Baker) Hong-Wa & Callm. (B), and NoronHia obovata (Baker) Hong-Wa & Callm. (C): Current localities (circles), historical localities (stars).