Warneckea albiflora R.D. Stone & N.P. Tenza, 2017

Stone, Robert Douglas & Tenza, Ntombiphumile Perceverence, 2017, Warneckea albiflora, a new species of W. subgenus Carnosae (MelastomataceaeOlisbeoideae) from coastal dry forest in northern Mozambique, Phytotaxa 311 (2), pp. 168-174 : 169-172

Warneckea albiflora R.D. Stone & N.P. Tenza , sp. nov. ( Figs. 1 , 2 )

Type:— MOZAMBIQUE. Cabo Delgado: Quiterajo, track through middle of Namacubi (Banana) Forest, 11°45'46"S, 40°20'19"E, elev. 125 m, 27 Nov 2008, J. E. Burrows & S. M. Burrows 10833 (holotype BNRH!, isotype K [ K 000738569]!).

Evergreen tree 2.5–8 m high; bark smooth, pale grey mottled with patches of pale brown; young branchlets subquadrangular, soon becoming terete with age; internodes 1.4–2.8 (–3.2) cm long. Leaves thinly coriaceous, 3- nerved from the base and with an additional pair of weaker submarginal nerves, dark green above, somewhat paler below; petioles 2–3 mm long; blades elliptic-lanceolate, (3.2–) 4.5–6.5 (–7.3) × 1.8–3 cm, narrowly cuneate at base, attenuate then acuminate towards the apex, acumen mostly 6–12 (–15) mm long, apex narrowly obtuse to ± pointed; midnerve impressed on the upper surface, prominent on the lower, often extending past the leaf apex as a short mucro; lateral nerves prominent on both surfaces (in dried material), curvilinear toward the base of the blade, forming shallow arches and becoming progressively weaker toward the leaf apex; lower surface of blade finely reticulate-areolate owing to a conspicuous network of purplish veinlets. Cymules sessile, clustered at the recently defoliated nodes just below the current leaves (rarely in the leaf axils); pedicels 3.5–4 mm long, subtended by several pairs of imbricate-decussate bracts; bracts ca. 1 mm long, ± rhombic in outline, cucullate and ± keeled toward apex on the abaxial side. Flowers white; hypantho-calyx obconic, 2 mm high × 3 mm wide; petals spatulate, 3 mm long × 2 mm wide; staminal filaments 4–5 mm long; anthers ca. 0.8 mm long, the connective strongly incurved by the ellipsoid, dorsal gland occupying the middle ⅓ on the dorsal side; style filiform, 6 mm long. Fruits unknown.

Additional specimens examined (paratypes): — MOZAMBIQUE. Cabo Delgado: Namacubi Forest, west of Quiterajo , 11°45'46.5"S, 40°21'18.1"E, elev. 90 m, 27 Nov 2008, F. Crawford 259 ( BNRH!, K!, P!) ; Quiterajo , 11°47'42"S, 40°20' 23"E, elev. 120 m, 24 Nov 2009, Q. Luke & P. Luke 13898 ( EA, K!, LMA, P!) ; Namacubi Forest, ca. 10 km west of Quiterajo village , 11°45'47.2"S, 40°21'42.8"E, elev. 99 m, 25 Nov 2009, D. J. Goyder et al. 6151 ( K!, LMA, P!) ; Namacubi Forest near Quiterajo , 11°45'23"S, 40°24'00"E, elev. 90 m, 08 Sep 2014, J. Timberlake & A. Massingue s.n. ( NU!) .

Distribution and habitat: —Known only from the Namacubi (Banana) Forest west of Quiterajo, Cabo Delgado province, northern Mozambique (for maps see Fig. 2 in Timberlake et al. 2011 and Fig. 2 in Stone 2013). According to data provided on specimen labels, the habitat is in dry, semi-deciduous coastal forest dominated by Guibourtia schliebenii (Harms) J. Léonard and Pteleopsis myrtifolia (M.A. Lawson) Engl. & Diels , on sandy soil at elevations of 90– 120 m.

Phenology: —Flowers in late November. Fruiting period unknown.

Conservation status: — Warneckea albiflora is known from a single location that is not in a protected area. The EOO is estimated as 12 km 2 and the AOO as 16 km 2 (assuming a 4 km 2 grid-cell size). Ongoing threats include continued clearing for subsistence agriculture, cutting of poles, uncontrolled fires, and possible road construction for oil-and-gas development which would increase access to and clearance of the forest ( Timberlake et al. 2011; Cheek & Darbyshire 2014). Accordingly, W. albiflora is provisionally assessed as Critically Endangered, CR B1ab(iii).

Etymology: —The epithet albiflora is an adjective referring to the white flowers of this species, this being the main diagnostic feature separating it from the closely related W. sansibarica .

Discussion: — Warneckea albiflora is placed in W. subgenus Carnosae on account of its combination of leaf blades with conspicuous network of purplish veinlets on the lower surface; sessile inflorescences agglomerated at the recently defoliated nodes; pedicels subtended by persistent, imbricate-decussate bracts; patelliform calyx limb with lobes obsolete; and anther connectives bearing a minute, dorsal oil-gland ( Stone and Andreasen 2010). The new species would key to Memecylon sansibaricum Taub. [≡ Warneckea sansibarica ] in the Flora Zambesiaca and the Flora de Moçambique (R. Fernandes and A. Fernandes 1978, 1980), but is readily distinguished from W. sansibarica by its narrowly elliptic, attenuate–acuminate leaves (acumen mostly 6 − 12 mm long) and white flowers borne on relatively short pedicels (3.5–4 mm long). In contrast, the leaves of W. sansibarica are elliptic with apices rounded to ± shortly and obtusely acuminate (acumen absent or if present then mostly 3–8 mm long); the flowers are generally pale blue to deep blue, and the pedicels are generally longer (6 − 15 mm). In the Namacubi Forest, W. sansibarica is represented by the collections J. Burrows & S. Burrows 10753 and 10765 (BNRH, K), Crawford et al. 266 (K) and Timberlake et al. 5486 and 5505 (K).

Also occurring in the same Namacubi Forest near Quiterajo is W. cordiformis , another close relative of W. sansibarica except being of smaller stature (a shrub or small tree 2–3 m vs. a larger tree 5–8 m) with young branchlets distinctly quadrangular and narrowly 4-winged (vs. terete to subquadrangular), leaves smaller and differently shaped (mostly 1.5–3 × 1.2–2.2 cm and ovate to cordiform vs. mostly 4–6.5 × 2.3–4 cm and elliptic with base cuneate), pedicels relatively short (1.5–3 vs. 6–15 mm), and flowers white (vs. pale to deep blue). Warneckea cordiformis is locally endemic in the Namacubi Forest, and is represented by the collections J. Burrows & S. Burrows 10773 and 10837 (BNRH, K), Goyder et al. 6095 (holotype K; isotypes LMA, NU, P), Luke 13887 (EA, K, P), and Timberlake et al. 5499 (K).

Remarkably, the Namacubi Forest is the only locality where three different species of W. subgenus Carnosae are known to occur together. Further study is needed to address questions of how the boundaries between these sympatric species originated and are maintained. For now, we can only confirm that the observed differences between them are consistent, i.e., the three distinct morphotypes do not appear to represent extremes in a continuous range of variation.

Figures

FIGURE 1. Image of the holotype of Warneckea albiflora (J.E. Burrows & S.M. Burrows 10833, BNRH). Source: Buffelskloof Nature Reserve Herbarium.

FIGURE 2. Living material of Warneckea albiflora (same individual as the type collection). A. Flowering branchlet; B. Trunk showing mottled character of the bark. Photographs by John E. Burrows.