Pavetta ankasensis W.D.Hawth.

Hawthorne, W.D. (2003). Six new Pavetta (Rubiaceae), including three ‘litter-bin’ species from the evergreen forests of Western Africa. Kew Bulletin 68: 559. https://doi.org/10.1007/s12225-013-9484-7

Type

Type: Ghana, Western Region, Ankasa forest, Hawthorne, Abu Juam, Gyakari, Ekpe ANKA 932 (holotype FHO).

Morphology General Habit

Low, little-branched shrub, 30 – 100 cm tall with leaves clustered at branchlet and stem tips

Morphology Branches

Branchlets with short dense hairs Axes of flowering branchlets rather flattened, not terete, indumentum like that on vegetative internodes.

Morphology Leaves Stipules

Stipule rather leathery, triangular or usually awned, c. 7 mm long including 4 – 5 mm awn; margin c. 1 mm wide below the awned section, thinner in texture than the main stipule body, joining the 1 mm long, supra-axillary collar; awn relatively more pronounced in the apical bud, up to 7 mm long beyond the basal 2 mm long triangular portion; inner face ± glabrous, without a fringe of hairs

Morphology Leaves Leaf lamina

Lamina of main stem leaves oblanceolate, 2 – 7.5 cm wide × 8 – 21 cm long (length/width c. 2.8), variously reduced on flowering shoots to as small as 2 × 5 cm; sometimes drying bluish especially along venation (as in P ixorifolia). Petiole short, 0.1 – 0.75 cm long, slightly winged with decurrent leaf base. Midrib above slightly channelled to slightly prominent

Morphology Leaves

Finer venation to at least sixth order prominent on both surfaces of dried leaves, reticulate, the finest areoles not markedly elongated (VDA < 1.5), 22 – 28 veins per cm in lines of any orientation in mid leaf Tertiary venation laxly reticulate to scalariform, 6 – 10 ‘rungs’ directly linking adjacent lateral nerves Leaves oblanceolate to spathulate, acuminate, matt below, with short (0.01 – 0.2 mm) dense hairs on midrib and petiole Lateral nerves 8 – 17 pairs, meeting in a loopy nerve 4 – 7 mm from margin, glabrous or with few very short hairs

Morphology Reproductive morphology Inflorescences

Inflorescence radius 1 – 1.5 cm Inflorescence terminal or on flowering branchlets from axils; axillary flowering branchlets 1.3 – 2 cm long (one non-flowering axillary branch seen 3.5 cm long), with a single pair of smaller than average leaves, at the node on which the terminal inflorescence is sessile

Morphology Reproductive morphology Inflorescences Bracts

Sheathing bracts with appressed short hairs; bracteoles linear 0.5 – 2 mm long.

Morphology Reproductive morphology Flowers Calyx

Calyx in bud c. 0.5 – 2 mm long including the (four) rounded to truncate, 0.5 mm long lobes

Morphology Reproductive morphology Flowers

Open flowers unknown (see notes under P sapoensis).

Morphology Reproductive morphology Fruits

Fruit globose, c. 8 mm diam., white when fresh, black when dried, in very short, compact infructescences, inflorescence axes not so far recorded as white (unlike P quasidigita).

Morphology Reproductive morphology Seeds

Seed ellipsoid to hemispherical, deeply excavated on inner surface, c. 7 × 4 × 4 mm

Distribution

Africa: SW Ghana.

Ecology

Known only from the three cited specimens from SW Ghana (Ankasa forest), in Wet Evergreen forest.

Conservation

Endangered (IUCN 2001): occurring in only two 2 km grid cells (AOO 4 km2) in Ankasa forest; it has proved highly elusive in spite of searches for fertile specimens, including during a full vegetation survey of the forest in 1998. As with Pavettasonjae, this is a Black Star species and as such has legal protection within Ghana’s forests. Ankasa forest is currently relatively well protected; if this were to change, P. ankasensis would become Critically Endangered (IUCN 2001).

Phenology

Flower and early fruits in January; mature fruits in March.

Note

Named after the type locality, Ankasa forest.

Differs from Pavetta quasidigita by having longer flowering branchlets and by lacking the distinctive finer venation of P. quasidigita. Leaves are less densely hairy below than in P. quasidigita. P. ankasensis differs from P. ixorifolia by having short flowering branchlets and subsessile leaves. See key above for differences from other litter-bin species.