Astropanax myrianthus (Baker) Lowry, G.M. Plunkett, Gostel & Frodin, 2017

Lowry Ii, Porter P., Plunkett, Gregory M., Gostel, Morgan R. & Frodin, David G., 2017, A synopsis of the Afro-Malagasy species previously included in Schefflera (Araliaceae): resurrection of the genera Astropanax and Neocussonia, Candollea 72 (2), pp. 265-282 : 272

A9. Astropanax myrianthus (Baker) Lowry, G.M. Plunkett, Gostel & Frodin , comb. nov. ( Fig. 1B ).

÷ Cussonia myriantha Baker in J. Linn. Soc., Bot. 20: 157. 1883. ÷ Schefflera myriantha (Baker) Drake in Grandidier, Hist. Phys. Madagascar 35: t. 403. 1896. ÷ Neocussonia myriantha (Baker) Hutch., Gen. Fl. Pl. 2: 79. 1967.

Typus: MADAGASCAR: sine loc., bud, Baron 2017 (holo-: K [ K00350556 ]!; iso-: G [ G00015604 ]!, P [ P00466304 ]!) .

= Schefflera myriantha var. attenuata Bernardi in Candollea 24: 101. 1969. Lectotypus (designated here): MADAGASCAR. Prov. Toliara: massif de l’Andohahela, haute vallée de la Sakamalio, [24°32’S 46°41’E], 1600- 1900 m, I.1934, fl., Humbert 13575 (P [P00466305]!; isolecto-: G [G00015603] image seen; P [P00466306, P00466307]!).

Habitat and distribution. – Astropanax myrianthus , as circumscribed here, is restricted to Madagascar, where it occurs in humid forest at scattered sites from the far north (Montagne d’Ambre National Park) to the extreme south (Andohahela National Park), at 950 to 2,350 m elevation ( MADAGASCAR CATALOGUE, 2017).

Notes. – Based on the results of our recent molecular phylogenetic work ( GOSTEL et al., 2017), Astropanax myrianthus is circumscribed here to comprise only the populations from Madagascar previously included in Schefflera myriantha by various authors (e.g., BAMPS,1974a, 1974b; BERNARDI,1969; FRODIN & GOVAERTS, 2004). While material from continental Africa long assigned to S. myriantha is essentially indistinguishable morphologically, molecular analyses show that if a broad circumscription of this taxon is applied, it is paraphyletic with respect to two clearly distinct and well delimited species in Madagascar ( Astropanax humblotianus and two as yet undescribed taxa). Moreover, the African and Malagasy material assigned to S. myriantha , as historically circumscribed, belongs to two distinct, well-supported clades in all molecular analyses, prompting GOSTEL et al. (2017) to conclude that two separate species must be recognized, which, despite their morphological similarity, can be distinguished unambiguous on the basis of geography. Specimens from Africa are therefore referred to Astropanax polysciadus (Harms) Lowry, G.M. Plunkett, Gostel & Frodin (see below). Material from the Comoro Islands was not available for the molecular study, so the placement of these populations must await additional analyses that include samples from this archipelago.

The type collection of Schefflera myriantha var. attenuata comprises three sheets at P, the most complete of which has been selected as the lectotype .

Figures

Fig. 1. – Photographs of Astropanax Seem. A. Astropanax monophyllus (Baker) Lowry, G.M. Plunkett, Gostel & Frodin; B. Astropanax myrianthus (Baker) Lowry, G.M. Plunkett, Gostel & Frodin; C. Astropanax barteri Seem.; D. Astropanax mannii (Hook.f.) Seem.; E. Astropanax stolzii (Harms) Lowry, G.M. Plunkett, Gostel & Frodin; F. Astropanax volkensii (Harms) Lowry, G.M. Plunkett, Gostel & Frodin.