Virotia leptophylla, (Guillaumin) L. A. S. Johnson & B. G. Briggs (Guillaumin) L. A. S. Johnson & B. G. Briggs

Hopkins, Helen C. F. & Pillon, Yohan, 2020, Virotia azurea (Proteaceae: Macadamieae), a striking new species endemic to New Caledonia and notes on V. francii and V. leptophylla, Candollea 75 (1), pp. 89-98 : 97

Notes on Virotia francii and

V. leptophylla

The following material was identified by Virot as Macadamia francii (≡ Virotia francii ) (based on his determinavit labels and the first three sheets were also cited in VIROT, 1968) and is re-determined here as V. leptophylla :

MacKee 12654, Farino: forêt Mépéou , Exploitation Forestière Germain ( P) ; MacKee 12655, ibid. loco, rejet de 12654 ( P) ; MacKee [leg. Gay] 15493, ibid. loco, état de jeunesse avancé ( P) ; Veillon 1618, Mt Arago ( P).

In addition, MacKee 18508 (Massif de Ton-Non, Roches Ouaïème, P) was determined by Virot as M. francii but is redetermined by us as V. vieillardii , a species confined to north-eastern Grande Terre and which has ovate-elliptic leaf blades with quite well-defined areoles and borne on relatively long petioles (up to 10 cm). These new determinations have been entered in SONNERAT (2020), where images of the sheets can be seen.

Among the specimens cited above, the field notes of MacKee 12654 described the flowers as “bleu clair à extrémité blanche”, and so resembling the flowers of V. azurea , although the flowers of V. leptophylla are usually white or pale yellow. However, the leaf blades of this MacKee collection are relatively short with comparatively long petioles, hence our determination of this sheet as V. leptophylla .

Removal of these collections from Virot’s concept of Macadamia francii , together with the description of Virotia azurea , means that V. francii is now a morphologically more homogeneous species restricted to ultramafic substrates in southern Grande Terre. Like both V. azurea and V. leptophylla , it commonly has elliptic, obovate-elliptic or rather long, narrow leaves; in V. francii , the petiole is (1–) 1.5–6 cm long and the blades 13–43 × 2.8–7.8 cm, with the base cuneate or narrowly cuneate (to decurrent) and sometimes unequal, and the apex is ± acute and mucronulate, broadly acute, obtuse or occasionally rounded-retuse; leaves in juvenile plants and regrowth shoots can be slightly larger. As mentioned above, V. francii is most easily distinguished by the intramarginal vein that extends from the base of the leaf to the tip. Its immature fruits are beaked, as in V. azurea , whereas those of V. leptophylla are ± circular in outline and unbeaked, although sometimes they have a small umbo that develops from the base of the style.

Virotia leptophylla is rather unusual in that it occurs on nonultramafic substrates in central Grande Terre and ultramafic ones in parts of the south, in the Thy valley (several collections; substrate ultramafic or a mosaic including ultramafic), Nord de la Conception (Balansa 2294, type, P; substrate probably ultramafic), and Haute Rivière des Pirogues , Forêt Faux Bon Secours (MacKee 38034, P; substrate ultramafic). As mentioned above, the adult leaves are usually narrowly obovate-elliptic, elliptic, ovate, or sometimes oblanceolate (petioles 1–4.5 cm long; blades 7.5–22.5 × 2.5–8.5 cm), with the base cuneate or narrowly cuneate and the apex obtuse to rounded and often retuse. Leaves from juveniles and small plants that flower in the understorey at c. 4 m high are usually narrowly ellipticovate (to 27 × 7 cm) with an acute-mucronulate apex and longer petioles (to 7.5 cm). Some specimens from the region of La Foa and Canala (McPherson 6387, P; McPherson 6119, P; MacKee 12654, P) have somewhat atypical long lanceolate leaves with secondary veins branching nearer the margin, tertiary veins more apparent, and more coriaceous leaf blades. Typical forms and intermediates occur in the same area, so these variants probably do not warrant recognition as a distinct entity.

The collection Tronchet et al. 462 (P) from Mt Görö Até is left unplaced for now. Its pink flowers and relatively short, densely flowered inflorescences are reminiscent of V. angustifolia (Virot) P.H. Weston & A.R. Mast but it differs from the latter by its leaf blades, which are less coriaceous and have a rounded, not pointed, apex, and distinct petioles that are 2 cm long (petioles absent or very short in V. angustifolia ). The Mn content of this specimen is modest (1047 ppm), suggesting that the plant was not growing on ultramafic substrate, whereas V. angustifolia is a strong Mn hyperaccumulator restricted to the ultramafic substrates of Tiébaghi. Tronchet et al. 462 appears to have a similar ecology to V. azurea and was collected within the distribution of V. azurea (and possibly V. leptophylla ), but its pink flowers and rounded leaf apices distinguish it from V. azurea , while its long leaf blades (34 cm) with thicker petioles (2 mm wide) distinguish it from V. leptophylla .