Amyrea humbertii Leandri

McPherson, Gordon, 2015, Observations on Madagascan Amyrea Leandri and Tannodia Baill. (Euphorbiaceae), Candollea 70 (1), pp. 141-144 : 142

Amyrea humbertii Leandri in Notul. Syst. (Paris) 9: 169. 1941.

Typus: M ADAGASCAR. Prov. Toamasina: Analamazaotra , 800 m, II.1919, Perrier de la Bâthie 9742 (lecto-: P [ P00098119 ] image seen; isolecto-: P [ P00098120 ] image seen) (lectotypified by RADCLIFFE-SMITH, 1998b) .

= Amyrea celastroides Radcl. - Sm. in Kew Bull. 53: 440. 1998. Typus: M ADAGASCAR. Prov. Toamasina: Forest reserve at Andasibe ; wet evergreen forest, 20.XII.1988, Miller 3773 (holo-: P [ P00098107 ] image seen; iso-: MO-3651586!), syn. nov.

= Amyrea stenocarpa Radcl. - Sm. in Kew Bull. 53: 451. 1998. Typus: M ADAGASCAR. Prov. Toamasina: Sahamamy, Perinet , 28.XII.1950, Service Forestier 2531 (holo-: P [ P00098135 ] image seen; iso-: K [ K000425610 ] image seen, MO-6570918!, P [ P00098136 ] image seen, TEF [ TEF000201 ] image seen), syn. nov.

Distribution and habitat. – Amyrea humbertii is widespread in Madagascar, from low to mid elevations in the eastern evergreen forests as well as from scattered localities in the central highlands and the western dry forests around Bemaraha.

Observations. – The diagnosis of A. celastroides states that it contrasts with A. humbertii in that it has wider leaves that are entire and thinly coriaceous, with thicker veins, as well as having longer inflorescences and smaller staminate disk glands. The holotype of A. celastroides does exhibit leaves in the stated 3-5 cm range, but in the lectotype of A. humbertii the leaves are up to 4.8 cm wide, and thus not significantly different. The leaf margins of this lectotype appear to be as near to entire as do those of Miller 3773, although specimens of A. humbertii often do have evident marginal teeth. The thickness of the leaf venation of the two specimens does not appear to differ. Inflorescence lengths in specimens not otherwise distinguishable from A. humbertii sometimes attain 9 cm, the maximum attributed to A. celastroides , and no difference in staminate disk gland size was observed in the 4 staminate flowering specimens examined.

In its diagnosis A. stenocarpa is distinguished from A. celastroides (placed above in the synonymy of A. humbertii ) by its narrow fruit, 12 × 7 mm. The isotype at MO bears fruits that measure 8-11 × 6-7 mm and are almost certainly immature, with longitudinally collapsed walls and locule apices that project above the central axis of the fruit. The immature fruits of A. humbertii sometimes show the same longitudinally collapsed walls and extended locule apices, and its mature fruits measure c. 11 × 11 mm. Given that Service Forestier 2531 is not otherwise distinct from A. humbertii , which is common in the forests near Perinet, I have no doubt that this type specimen represents A. humbertii .