Ruellia (Tripp & Darbyshire, 2017)

I., Darbyshire, J., Tchamba & Manzitto-Tripp, E. A., 2023, A synopsis of RUEllia (Acanthaceae) in Angola, including two species new to science, Rheedea 33 (4), pp. 246-269 : 249-250

Key to species of Ruellia in Angola *:

1. Corolla tube with narrow cylindrical portion shorter than or subequal in length to expanded throat (ratio 0.35–0.9: 1), corolla infundibular to broadly so ......................................................................2

1. Corolla tube with narrow cylindrical portion of corolla tube markedly longer than expanded throat (ratio 1.8–3.5:1), corolla appearing salver form except for expanded throat ...........................6

2. Both lobes of stigma well-developed; stamens subequal in length, not didynamous; calyx lobes linear, 19–24.5 mm long; stems and young foliage densely eglandular-pilose to -villose; seeds with hygroscopic hairs occurring across the surface though most dense on the rim .......6. R. angolensis

2. Only one of the stigma lobes well developed, the second lobe suppressed; stamens clearly didynamous; calyx lobes lanceolate to linear, 2.2–13 mm long; stems and young foliage not so densely pilose to villose, or if conspicuously pilose ( R. praetermissa ) then hairs mainly glandular; seeds with hygroscopic hairs confined to the rim, surfaces elsewhere glabrous or with very short inconspicuous hairs only .........................................3

3. Leaves ± broadly ovate with base shallowly cordate or truncate; inflorescences conspicuously pedunculate, peduncles sometimes curved-ascending, 5–52 mm long; corolla 48–51 mm long; calyx lobes densely glandular-pilose to -villose....................................................... 5. R. currorii

3. Leaves ovate, elliptic or somewhat obovate, base (broadly) cuneate or attenuate; inflorescences (sub-)sessile in leaf axils; corolla 15–33 mm long; calyx more sparsely hairy, either with short eglandular hairs only or mixed eglandular and glandular hairs .............................................................4

4. Stems densely glandular-pilose; leaves ovate, petioles 15–43 mm long; capsule puberulous; calyx 5.5–8.5 mm long, lobes up to 6.2 mm long. ............................................................ 2. R. praetermissa

4. Stems lacking glandular hairs or rarely very few present around the nodes (can be present on the petioles); leaves variously shaped but usually not so long-petiolate, petioles 2–23 mm long; if capsule puberulous then calyx (6–) 7.5–14.5 mm long, lobes usually over 6.5 mm long....................5

5. Ovary and capsule puberulous; calyx (6–) 7.5– 14.5 mm long with linear lobes (4.3–) 6.5–12.5 mm long; leaves typically ovate to ovate-elliptic with apex acute or attenuate; stems antrorsepuberulous and with spreading or ascending longer hairs or only the latter ..........1. R. prostrata

5. Ovary and capsule glabrous; calyx 3.3–5.7 mm long with lanceolate lobes 2.2–4 mm long; leaves typically elliptic, oblong-elliptic, ovate-elliptic or some elliptic-obovate, often with apex obtuse or rounded; stems retrorse-pubescent to -puberulous, rarely also with longer crisped spreading hairs ..........................................3. R. patula

6. Stigma with only one lobe well-developed; basal cylindrical portion of corolla tube 26–33.5 mm long; calyx 5–9.5 mm long, lobes linearlanceolate, with short ± ascending eglandular hairs on margins and midveins only, rarely with few scattered glandular hairs; leaf bases broadly cuneate or shortly and broadly attenuate ................................................................... 4. R. togoensis

6. Stigma prominently 2-lobed; basal cylindrical portion of corolla tube 41–61 mm long; calyx 14– 29 mm long, lobes either linear and eglandular-pilose to villose, or ligulate and shortly glandular-pubescent with longer eglandular hairs along margins, midveins and fused basal portion; leaf bases rounded, shallowly cordate or broadly obtuse .............................................................................7

7. Capsule puberulous; stems with mixed dense short white retrorse eglandular hairs and long patent lustrous yellow-brown eglandular hairs; calyx lobes linear, densely long eglandular-pilose to -villose with interspersed shorter eglandular and few glandular hairs; bracteoles narrowly oblong-elliptic, 3.5–4 mm wide; corolla lobes with only eglandular hairs externally; anthers 3.4–4.2 mm long .........................7. R. quipungoensis

7. Capsule glabrous; stems shortly viscid glandular-pubescent and retrorse-puberulous,and with long white eglandular hairs often confined to older stems, not lustrous; calyx lobes ligulate, shortly glandular-pubescent with longer eglandular hairs confined to margins and midveins of each lobe and to fused basal portion; bracteoles ovate to broadly so, 5.5–16 mm wide; corolla lobes with both glandular and eglandular hairs externally; anthers 4.7–5 mm long ...............8. R. bignoniiflora

* Key refers only to specimens from Angola and immediately neighbouring regions and so (intentionally) does not necessarily reflect the full range of variation within the widespread species.

1. Ruellia prostrata Poir. in Lam. et al., Encycl. 6: 349. 1804; C.B. Clarke in Fl. Trop. Afr. 5: 46. 1899; Hiern, Catalogue Afr. pl. coll. Friedrich Welwitsch 1853-1861, Dicotyledons, part IV: 808. 1900; Vollesen in Fl. Trop. E. Afr. Acanth. (Part 1): 204. 2008 & in Fl. Zambes. 8(5): 137. 2013. Type: INDIA, s.loc., M. Dupuis s.n. (holo P, n.v.).