Monanthotaxis aquila P.H.Hoekstra

Hoekstra, P. H., Wieringa, J. J., Maas, P. J. M. & Chatrou, L. W., 2021, Revision of the African species of Monanthotaxis (Annonaceae), Blumea 66 (2), pp. 107-221 : 125-126

2. Monanthotaxis aquila P.H.Hoekstra — Fig. 3 ; Map 3

Monanthotaxis aquila P.H.Hoekstra in P.H. Hoekstra et al. (2016) 74. — Type: C. Geerling 2327 (holo consisting of 2 sheets: WAG0005568 , WAG0005569 ; iso BR0000015315335 ), Ivory Coast, Sassandra, Dakpadou-Sago, 27 Mar. 1968.

Liana; young branches covered with short reddish brown hairs c. 0.1 mm long, becoming glabrous; old branches dark brown. Leaves: petiole 4–6 mm long, 0.7–1.1 mm diam, terete, indument as on branches; lamina oblong-elliptic to slightly obovate, 3.5–11.5 by 1.9–4.8 cm, 1.8–2.7 times longer than wide, chartaceous, not punctate, glossy dark green above, dark silvery green below, above glabrous or primary vein covered with few, short hairs, below becoming glabrous, primary vein of young leaves covered with appressed, yellowish hairs 0.1–0.2 mm long, base cuneate to rounded, glands hardly visible, apex acute to acuminate, acumen to c. 10 mm long, secondary veins 6–8 per side, from base curving upwards, tertiary venation percurrent. Inflorescences ramiflorous, axillary or supra-axillary, composed of solitary flowers or 2- or 3-flowered rhipidia; sympodial rachis 0.5–2 mm long, densely covered with appressed, short hairs; flowering pedicels 10–18 mm long, 0.3–0.4 mm diam, sparsely covered with appressed hairs; lower bracts ovate, 0.6–0.9 by 0.3–0.5 mm, indument as on rachis; upper bract in lower half of pedicel, broadly ovate to narrowly ovate, 0.4–0.7 by 0.3–0.4 mm, indumentum as on pedicel; flower buds ovoid to deltoid. Flowers bisexual; sepals connate at the base, depressed ovate, c. 0.6 by 1.2–1.3 mm, apex obtuse, covered with appressed, yellowish hairs; receptacle 1.6–2 mm diam, flat; petals yellow, 6, in two whorls, base of inner petals visible in bud, outer petals ovate, 3.4–4.5 by 2.1–2.8 mm, outside sparsely covered with appressed, yellowish hairs, inside with appressed, very short hairs at the apex, inner petals elliptic to slightly rhombic, 2.3–3.5 by 1.3–1.5 mm, outside covered with very short yellowish hairs at the apex and in the centre, inside only with hairs at the apex; stamens 9, in one whorl, free, clavate, 0.7–0.8 mm long, filaments 0.3–0.4 mm long, thecae latrorse, connective truncate, quadrate seen from above, slightly papillate, staminodes 6, alternating with the stamens, but absent where in front of inner petals, c. 0.3 mm long, glabrous; carpels 12 or 13, ellipsoid, 0.9–1 by 0.4–0.5 mm, densely hairy, ovules 2 or 3, lateral, stigma subsessile, globose, c. 0.1 mm diam, glabrous. Monocarps and seeds not seen.

Distribution — Ivory Coast (Sassandra).

Habitat & Ecology — In secondary forest, on sandy soil. Flowering: end of March.

Preliminary IUCN conservation status — Critically Endangered ( CR): B2 ab(iii). AOO: 4 km 2. Only known from the type collection and the forests of that area are under serious threat ( Chatelain et al. 1996) .

Notes — 1. Monanthotaxis aquila belongs to a group of species with bisexual flowers, ovoid flower buds, axillary, cauliflorous or ramiflorous inflorescences and where staminodes are present these alternate with the stamens. It differs from the majority of the species of this group in having oblong-elliptic leaves, a character shared with M. couvreurii and M. atopostema . Monanthotaxis couvreurii differs from those species by having 13–16 basally connate stamens and the absence of staminodes.Although M. aquila is phylogenetically less related to M. atopostema than M. couvreurii ( Fig. 1 , clade C) it looks morphologically more similar to M. atopostema . The petals are more broadly ovate in M. atopostema with the petals only being slightly longer than wide, while in M. aquila the petals are much longer than wide; M. atopostema has 15–20 carpels per flower, and the staminodes are only slightly smaller than the stamens, while M. aquila has 12 or 13 carpels per flower and the stamens are twice as large as the staminodes. The difference in number of ovules as noted by Hoekstra et al. (2016) is incorrect, it was based on the number of seeds per monocarp of a misidentified specimen in BR. Furthermore, one of the few flowers existing of M. atopostema has now been examined and it has 2 or 3 ovules per carpel, just as M. aquila .

Figures

Map 3 Distribution of Monanthotaxis aquila P.H.Hoekstra (●) and M. atewensis P.H.Hoekstra (■).

Fig. 3 Monanthotaxis aquila P.H.Hoekstra. a. Leaf; b. leaf detail; c. in- florescence; d. flower (all from Geerling & Bokdam 2327). — Drawing by M. Spitteler, reproduced from Hawthorne & Jongkind (2006).

Fig. 1 Bayesian 50 % majority rule consensus tree of the genus Monanthotaxis. Asterisks at nodes indicate node support, i.e., *** Strong node support, ** moderate node support, * weak node support, see Hoekstra et al. (2018). The letters A to K with adjacent black bars indicate the clades. The triangles, circles and squares represent morphological characters of the species which are of some use to distinguis the clades. Green triangles = staminodes absent, red triangles = staminodes present. Green circles = petals in one whorl, red circles = petals in two whorls, yellow circles = petals in bud basally in one whorl, at the top outer petals overlapping the inner ones. Green squares = inflorescences extra-axillary or if cauliflorous also extra-axillary inflorescences present, red squares = inflorescences axillary, supra-axillary or cauliflorous, red and green squares = both extra-axillary and axillary inflorescences present.