Crepidorhopalon namuliensis I.Darbysh. & Eb.Fisch., 2019

Crepidorhopalon namuliensis I.Darbysh. & Eb.Fisch. View in CoL , sp. nov. — Fig. 1d–e View Fig , 2d–e View Fig , 3

Closely resembling Crepidorhopalon whytei but differing in the inflorescence and distal internodes having a conspicuous glandular-pubescent indumentum (vs inflorescence and stems essentially glabrous or eglandular-pubescent only, sometimes with scattered (sub)sessile glands); in the lower lip of the corolla being white or at most tinged pale blue (vs lower lip of corolla blue, purple or mauve); and in having the combined characters of axillary inflorescences and foliaceous bracts with corollas 13.5–16.5 mm long (in C. whytei , if the bracts are foliaceous and so the flowers appear axillary, then the corolla is 16–24 mm long). — Type: Patel 7319 (holo K; iso LMA), Mozambique, Zambezia Prov., Namuli Mt, Muretha Plateau, fl. & fr. 25 May 2007.

Etymology. Crepidorhopalon namuliensis is named after Mt Namuli, a key locality for plant diversity and endemism in Mozambique and the only known site for this species.

Perennial herb, with numerous stems radiating from a central rootstock, at first erect but becoming scrambling or trailing, up to 50 cm long or more; stems brittle, markedly 4-angular, somewhat winged along the angles, with short spreading or ascending multicellular eglandular hairs and short spreading glandular hairs, the gland tip orange, becoming sparse on mature stems; internodes of fertile leafy stems 10– 22 mm long when mature, those of sterile stems sometimes much longer. Leaves sessile, broadly ovate, 9–20 by 8–18 mm, base rounded or shallowly cordate, margin serrate or shallowly so with 2 – 5 teeth per margin, apex acute or obtuse; primary venation palmate, with 5 or 7 main veins from base; sparsely puberulous with glandular and eglandular hairs mainly on margin and main veins beneath, surfaces also with sunken glands drying brown, most visible on lower surface. Flowers axillary, solitary; bracts foliaceous, only slightly reducing in size distally; bracteoles absent; pedicels 2.7–5.5(–6.5) mm long, shortly glandular-pubescent. Calyx 5–7.8 mm long, lobes lanceolate, somewhat unequal in length, longest lobes 3.3–4.2 mm long, apices can become divergent at maturity, 5-veined, somewhat hyaline between the veins, external surface shortly glandular-pubescent, margins of lobes eglandular-pubescent. Corolla 13.5–16.5 mm long, tube and upper lip whitish to purple, lower lip white or at most tinged pale blue, with (?or without) a yellow patch in the mouth, external surface glandular-puberulous, upper lip also with pale longer eglandular hairs; tube 7.5–8.5 mm long, cylindrical but slightly contracted in midpoint where 1.3–2 mm wide and widened at mouth where 2 –4 mm wide, internal surface with 4 lines of subsessile glands in proximal half; upper lip ovate, 3.5–5 by 4 – 5 mm, apex emarginate, internal surface with numerous minute glands; lower lip 6.5–8.5 mm long, 3-lobed, median lobe rounded-obovate, 3.7–4 by 4.5–5.3 mm, lateral lobes rounded-elliptic, 4–4.5 by 4.2–5 mm, margins of lobes somewhat irregular, bosses on palate of lower lip with blunt-tipped multicellular hairs. Stamens 4, ventral stamens spurred, spurs clavate, 1.2–1.75 mm long, papillate, filaments above spurred portion 4–4.3 mm long; posterior stamens with filaments 1.3–2 mm long; anthers of the two pairs of stamens adhering, thecae 0.7–0.9 mm long. Ovary 1.3–1.7 mm long, with sessile glands on surface; style 6.7–8.3 mm long; stigma fan-shaped and minutely fringed. Capsule ellipsoid, brown, ± equal in length to calyx or slightly shorter, to 7.5 mm long, apex acute; seeds ± 1–1.15 by 0.75 mm, with longitudinal ridges and furrows.

Distribution & Ecology — Crepidorhopalon namuliensis is apparently endemic to Mt Namuli in Zambezia Province of northern Mozambique. It occurs in montane grassland at 1730–1870 m elevation, favouring damp ground over rock where it can be associated with typical seepage assemblages including Cyperus , Xyris , Pimpinella and Senecio species together with Loudetia simplex (Nees) C.E.Hubb. (fide Mphamba 3).

Additional specimens seen. MOZAMBIQUE, Zambezia Prov., Namuli Mt, Muretha Plateau ,fl. & imm.fr. 24 May 2007, T . Harris 158 ( K, LMA [not found]); Namuli Mt, Muretha Plateau , Mukocha Forest , fl. 28 May 2007, Timberlake 5063 ( K, LMA [not found]); Namuli Mt, Muretha Plateau, fl. 17 Nov. 2007, Mphamba 3 ( K, LMA); below base of Namuli Peak, Serra de Gurue , fl. 25 Apr. 2008, Würsten 186 ( BR) .

Conservation — This species has been assessed as of Least Concern ( Matimele et al. 2017). Although it is known only from Mt Namuli there are no known threats to this species or its habitat at present as the montane grasslands of Namuli are not subject to settled agriculture and the human impact is low. However, this species and the other Namuli grassland endemics should be carefully monitored as any disturbance or change to this habitat could quickly result in them becoming threatened with extinction. The impact from deliberate dry season burning should be carefully monitored in particular.

Notes — This species is separated from other members of the Crepidorhopalon whytei complex primarily by having a conspicuous glandular indumentum and pale corollas. In addition, the internodes of the majority of the stems are rather short such that the plants appear more densely leafy than is seen in other taxa within this complex. The corollas are typically smaller than those of forms of C. whytei that have foliaceous bracts, but they fall well within the overall range of corolla size in C. whytei (see Note to that species).

Mt Namuli is emerging as a site of high importance for plant diversity and endemism, with 14 strict endemic species and two strict endemic subspecies now known. Most of these taxa, such as Coleus caudatus E.Downes & I.Darbysh. and Crotalaria namuliensis Polhill & T.Harris , are restricted to the montane grassland and wet flushes where Crepidorhopalon namuliensis is found ( Harris et al. 2011, Downes & Darbyshire 2017). These habitats are particularly rich in flowering herbs and geophytes during the main rainy season (J. Timberlake, pers. comm., based on observations made on Mt Namuli in Feb. 2017), a time when there has been almost no botanical collecting on Namuli to date, hence the chances of discovering further new endemic species at this site are high ( Downes & Darbyshire 2017). This locality is certain to qualify as an Important Plant Area (IPA) under the ongoing programme of IPA identification in Mozambique (see https://www.kew.org/science/projects/ tropical-important-plant-areas-tipas-mozambique; Darbyshire et al. 2017).