Monanthotaxis filipes P.H.Hoekstra, 2016

Hoekstra, Paul H., Wieringa, Jan J. & Chatrou, Lars W., 2016, A nonet of novel species of Monanthotaxis (Annonaceae) from around Africa, PhytoKeys 69, pp. 71-103 : 80-83

Monanthotaxis filipes P.H.Hoekstra sp. nov. Figs 6 , 7 , Table 2

Type.

TANZANIA, Lindi district, Rondo plateau, Rondo forest Reserve , 10°07'S; 39°13'E, 7 February 1991, G.S. Bidgood 1402 (holotype: K [2sheets!]; isotypes: BR [BR0000013186036!], C!, EA!, MO [4027188!], P [P01967237!], UPS!, WAG [WAG0071696!]) .

Diagnosis.

This species is similar to Monanthotaxis trichantha (Diels) Verdc. because of the dense yellow short indumentum on the young stems. It differs in the pendulous flowers on filiform pedicels, and in the outer petals covering the inner petals in bud.

Description.

Shrub, 1 m tall; young branches yellow-brown, with dense appressed to ascending yellowish hairs 0.3-0.7 mm, old branches dark brown to greyish brown, cylindrical, glabrescent with many lenticels. Leaves: petioles 3-5 × 0.7-1.0 mm, indumentum as branches; lamina 3.7-10.7 × 1.5-4.4 cm, length:width ratio 1.6-3.3, oblong to elliptic to slightly obovate, base rounded, truncate or slightly subcordate, with thickened margin at base, apex acute, chartaceous, discolorous, abaxially pale bluish green adaxialy soon glabrescent, with whitish appressed hairs when young, abaxially densely covered with ascending yellowish white hairs, venation eucamptodromous, midrib impressed adaxially, secondary veins 7-10, first straight halfway curving upwards, tertiary venation scalariform. Inflorescences supra-axillary, 2-6 mm above leaf axil, 1-2-flowered rhipidium; sympodial rachis 0-1 mm; flowering pedicels filiform 18-55 × 0.2 mm, with a few scattered ascending to erect hairs; lower bract strongly reduced or wanting; upper bract halfway the pedicel, very small, 0.3 × 0.1 mm or just a dense tuft of hairs or wanting; flower buds rounded. Flowers bisexual, pendulous; sepals 3, connate at the base, broadly ovate to almost cupuliform, 0.5 × 1.1-1.2 mm, obtuse to rounded, with dense yellow appressed hairs; receptacle 1.5-2 mm in diameter, flat; petals creamy white, 6 in two whorls; outer petals, 2.5-2.7 × 2.8-3.6 mm, broadly ovate, densely covered with short yellowish hairs on the outside and apex of the inside, glabrous at base of inside; inner petals 1.9-2.0 × 1.2-1.4 mm, ovate to rhombic, indumentum as in outer petals; stamens (13?-)15 in one to two whorls, free, flattened obovate, 1.1-1.3 mm long, filaments 0.3-0.4 mm long, anthers extrorse, connective truncate, not hiding anther cells, glabrous, staminodes 0; carpels 9, 1.2 × 0.2-0.3 mm, subcylindric, densely hairy, but glabrous near apex, with 2 lateral ovules, stigma elongate 0.4 mm, grooved, glabrous. Fruits unknown.

Distribution.

Tanzania, Lindi Region. Figure 7 .

Ecology.

Steep escarpment with dense thicket, stony-gravelly soil at 700 m altitude.

Phenology.

Flowers collected the 7th of February.

Conservation status.

Proposed IUCN Red List Category: Critically Endangered (CR): B2ab(ii, iii), only known from one collection in the Rondo Forest Reserve in South-east Tanzania. Although it occurs in a forest reserve, satellite images provided by Google Earth (assessed May 2016) show that a major part of the forest in the reserve systematically has been removed, and forest cover is declining over the years.

Etymology.

From the latin fili, thread-like, and pes, foot/stalk; referring to the filiform pedicels.

Discussion.

This species is vegetatively very similar to Monanthotaxis trichantha which also occurs in South-East Tanzania. The flowers and inflorescences are very different with Monanthotaxis filipes having pending flowers on long pedicels and the inflorescences supra-axillary, while Monanthotaxis trichantha has short pedicels which are extra-axillary or leaf-opposed (table 2). Apart from Monanthotaxis filipes , long filiform pedicels only occur in some species of Monanthotaxis from Madagascar (e.g. Monanthotaxis caesia (Diels) Verdc. and Monanthotaxis heterantha (Baill.) Verdc. These species lack the dense indumentum on the young twigs. Also Monanthotaxis oligandra Exell has pending supra-axillary inflorescences, but in this species the sympodial rachis (peduncle) is filiform instead of the pedicels, which are very short. Furthermore, Monanthotaxis oligandra lacks the dense yellow pubescence and has very different flowers with all petals in a single whorl.

Figures

Figure 6. Monanthotaxis filipes P. H. Hoekstra. A-H drawn from the type (Bidgood 1402). A Habitus B Leaf with flower C Flower with petals removed D Outer petal inside E Stamen inside F Stamen lateral G Stamen outside H Carpel. Illustration by H. de Vries.

Figure 7. Distribution map of Monanthotaxis filipes (red square) in Tanzania and Monanthotaxis komorensis (green circles) on the Comoros archipelago.