Capurodendron nanophyllum L. Gaut. & Naciri, 2018

Gautier, Laurent & Naciri, Yamama, 2018, Three Critically Endangered new species of Capurodendron (Sapotaceae) from Madagascar, Candollea 73 (1), pp. 121-129 : 127-129

Capurodendron nanophyllum L. Gaut. & Naciri , spec. nova ( Fig. 6 ).

Holotypus: MADAGASCAR. Prov. Toliara: Reg. Androy, près du village d’Ankorakosy , au SSE de Tsihombe, 17.XII.1968, fl., Service Forestier 28521 ( G [ G00418688 ]! ; iso-: P [ P04570991 ]!).

Capurodendron nanophyllum L. Gaut. & Naciri differs from C. androyense Aubrév. by its longer and more slender pedicels (4-5 × 0.3 mm vs 1-5 × 0.5 mm) that are sparsely whiteciliate vs densely golden-pubescent. Vegetatively, the leaves of C. nanophyllum are narrower (1.5-2.3 mm vs 4-11 mm) and have an inconspicuous venation (vs distinctly reticulate); they are almost sessile (vs with a distinct 2-3 mm petiole).

Shrub, height unknown, presumably with white latex; ultimate twigs 1 mm diameter, bark grey, rugose, longitudinally ridged, with short (2 to 4 mm long) lateral branches with numerous scars of fallen leaves and pedicels (brachyblasts). Leaves presumabely caducous, 2 to 10 spirally arranged at the tip of the brachyblasts, sessile or indistinctly petiolate; blades spathulate, base acute, apex rounded, 0.45-0.9 × 0.15-0.23 cm; upper side glossy, olive green to brownish when dry, loosely pubescent when young, later glabrous, venation indistinct or shallowly impressed; lower side dull, greyish green when dry, loosely pubescent, venation inconspicuous, with 1-3 very weak secondaries on each side. Flowers at the apex of brachyblasts, among the leaves; flowering pedicels slender, 4-5 × 0.3 mm, broadening to 0.6 mm below the flower, with scattered malpighiaceous white trichomes 0.3 mm long. Sepals 5, quincuncial, convex, ovate, 2.6 × 1.2 mm with an acute apex; glabrous inside and densely white-ciliate outside. Corolla gamopetalous with 5 lobes, glabrous, tube 2.0 mm long, lobes broadly lanceolate, 2.5 × 0.9 mm, contorted in bud, spreading at anthesis. Stamens 5, filaments 0.8-1.0 mm long, attached to the top of the corolla tube. Anthers attached to the filament at 1/3 of their length, extrorse 1.2 × 0.7 mm at the broadest, connective and adjacent side of the anthers villous, prolonged in a 0.2 mm acute mucro. Staminodes 5, alternate with respect to petals and stamens, broadly lanceolate and long-acuminate, 2.0 × 0.8 mm, densely villous with creamy trichomes, connivent and concealing the ovary. Ovary shallowly 5-lobed, 1.4 mm high × 0.9 mm broad, glabrous to minutely papillose, with 5 ovules, style 5 mm long, glabrous, 0.18 mm diameter, stigma faintly 5-lobed. Fruit unknown.

Etymology. – The epithet refers to the very small leaves, the smallest in the genus.

Distribution, ecology and phenology. – The species is only known from a single collection in the xerophilous thicket in the extreme South of the island, in the Southwestern Phytogeographical Domain ( HUMBERT, 1955). The flowering collection was gathered in December.

Conservation status. – With a single location known outside of the protected area network in a region where the xerophilous bush has been widely converted to agriculture and is subject to fire damage, C. nanophyllum is assigned a preliminary IUCN conservation status of “Critically Endangered” [CR B1ab(iii)+B2ab(iii)]. It should be further mentioned that recent attempts to collect the new species have failed, but this can be attributed to imprecise location of the type collection.

Notes. – Capurodendron nanophyllum has the smallest leaves in the genus and represents the most extreme adaptation of this humid forest group to arid habitats. It is only known by its type collection near Tsihombe, one of the driest parts in Madagascar, within the wide range of the relatively variable C. androyense . Although the latter may have leaves almost as small as those of the new species, they are never as narrow. The difference in venation is also striking with veins inconspicuous in C. nanophyllum whereas they are clearly visible on C. androyense . In the latter species, veins are conspicuous, especially on the lower side where they are highlighted by a dense golden indumentum, whereas the new species has scattered whitish trichomes only. Besides, C. androyense leaves are petiolate whereas C. nanophyllum leaves are sessile. Furthermore, the flowers of the new species are borne on distinctly longer and more slender pedicels.

Figures

Fig. 6. - Capurodendron nanophyllum L. Gaut. & Naciri. A. Corolla opened seen from inside; B. Longitudinal section of flower; C. Flower; D. Transverse section of ovary; E. Flowering branch; F. Brachyblast with leaves and post-anthesis flower; G. Corolla opened seen from outside. [Drawings: G. Loza]