Ruellia otaviensis P.G.Mey.

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 : 250-266

Ruellia otaviensis P.G.Mey. in Mitt. Bot. Staatssamml. München 2: 171. 1956; Makholela in Figueiredo & Smith, Pl. Angola: 24. 2008. Type: NAMIBIA, Otjozondjupa region, distr. Grootfontein, Asis , fl. & fr., 08.01.1934, O.H. Volk 694 (holo M [M0109659 digital image!]). FiGS. 1A–c & 2

Flowering & fruiting: This species has been recorded as flowering in Angola mainly in January to April but also in November; the few fruiting records are from January and October. Peak flowering corresponds to the latter half of the rainy season in Angola.

Habitat: Occurs in a variety of woodland types, gallery forest margins and sometimes in more open grasslands; c. 20–1700 m elevation.

Distribution: Widespread in eastern and southern tropical Africa, Arabia and the Indian subcontinent with scattered records elsewhere in tropical Asia and the Pacific region. In Angola it occurs in the west in Bengo, Benguela, Cuanza Sul, Cunene, Luanda and Namibe provinces.

Specimens examined: ANGOLA, Bengo prov., Ambriz, fl. & fr., 12.1872, J.J. Monteiro s.n. (K); Ibid., fl., 03.1873, J.J. Monteiro & R. Monteiro s.n. (K); Quicama , escarpment base below Cauá , fr., 02.10.1974, B.J. Huntley 3535 ( LUBA) ; Dande , fl., 03.2014, R. Ferreira (photo https://www.inaturalist.org/ observations/66702379);SantaAmboleia,fl.,11.2022, A. Martins (photos https://biodiversidadeangola. com/plants/specimen/175) . Benguela prov., along dirt track to W that leaves main highway between Benguela and Lubango , fl., 09.04.2017, E. Tripp & K. Dexter 6911 ( COLO, K, LUBA) . Cuanza Sul prov., Picada para o Agro-Catuto a 5 km do cruzamento de estr. Novo Redondo [Sumbe]– Gabela , fl., 26.04.1967, B. Teixeira et al. 11524 ( COI, digital image) . Cunene prov., Curoca, Chitado, na estrada para a Chipa , fl. & fr., 23.01.1962, O. Azancot de Menezes & C. Henriques 137 (K) . Luanda prov., Loanda , fl. & fr., s.d., F. Welwitsch 5063 (BM [BM001124281] pro parte, LISU [LISU223326 digital image, excl. right-hand plant])–see note to R. bignoniiflora . Namibe prov., Mocamedes, andados 8 km de Camucuio para Lola , fl., 07.01.1956, E.J. Mendes 1230 ( LISC) ; Mocamedes, Vila Arriaga [Bibala], fl., 25.01.1962, G. Barbosa & F. Moreno 10129 (K, LUBA) ; Curoca, ao km 30 do trajecto Oncócua–Ompupa , fl., 19.03.1973, A. Menezes et al. 4766 ( LUBA) .

Conservation status: A widespread and often locally common species, here assessed as of Least Concern (LC).

Notes: For a full description, bibliography and synonymy of Ruellia prostrata relevant to continental Africa, see Vollesen (2008, 2013). Only specimens seen from Angola are cited here, and only those from Angola and immediately neighbouring areas (primarily Namibia) were considered when developing the key. Several taxa–infraspecific or separate species–may ultimately be recognised within this widespread and variable species following additional study.

In Angola, the flowers are usually white ( Fig. 1a,b ) but in some specimens ( e.g. Mendes 3840) they are recorded as pink or tinged pale purple. Pink and purple flowers are frequent elsewhere within its range ( Fig. 1c is faintly pink).

2. Ruellia praetermissa Schweinf. ex Lindau in Bot. Jahrb. Syst. 20: 15. 1894; C.B. Clarke in Fl. Trop. Afr. 5: 45. 1899; Heine in Fl. W. Trop. Afr. 2: 396. 1963; Vollesen in Fl. Trop. E. Afr. Acanth. (Part 1): 208. 2008 & in Fl. Zambes. 8(5): 140. 2013. Lectotype (designated by Vollesen, 2013): SOUTH SUDAN, Warrap state, Bongo , Gir , fl. & fr., 27.07.1869, G. Schweinfurth 2155 (K [K000393976!]; isolecto P [P00436143 digital image!], S [S09-2682 digital image!]). Residual syntypes: SOUTH SUDAN, Western Equatoria state, Niamniam, Nabambisso, fl., 01.05.1870, G. Schweinfurth 3754 (n.v.); Tukamis, Saiba Indimma, fr., 26.05.1870, G. Schweinfurth 3789 (n.v.).

Ruellia patula sensu C.B.Clarke in Fl. Trop. Afr. 5: 45. 1899, pro parte quoad spec. ex W Africa, non Jacquin, Misc. Austriac. 2: 358. 1781. FiG. 2

Weak-stemmed perennial herbs or subshrubs, 25– 160 cm tall; young stems 4-angular, sulcate in dry state, glandular-pilose with patent, multicellular often somewhat crisped hairs 1–1.2 mm long, with occasional interspersed longer multicellular eglandular hairs 1.5–1.7 mm long. Leaves on slender petioles 15–43 mm long, indumentum as for stems, dense; blade ovate to broadly so, 48–73 × 27–43.5 mm (l: w ratio 1.4–2.1: 1), base broadly cuneate or shortly and broadly attenuate, margins entire or shallowly crenulate, apex attenuate to shortly acuminate, upper surface eglandular-pilose, hairs multicellular, 1.5–2.3 mm long, appearing deflated in dry state, lustrous and often pale yellowish, with or without numerous additional fine, short eglandular hairs to 0.2 mm long, sometimes with occasional glandular hairs along margins; lower surface pubescent, hairs coarser and longer on the main veins; cystoliths numerous, linear; lateral veins 5–6 per side. Inflorescences axillary in distal leaf axils, each 1–2-flowered, opposite, sessile; bracteoles elliptic or oblanceolate, 6.5–16 × 2–5.5 mm, indumentum as leaves. Calyx 5.5–8.5 mm long, fused at base for 1.2–2.2 mm; lobes linearlanceolate, 0.5–0.8 mm wide, each with prominent midvein, can be glaucous particularly along margin, external surface pilose with mixed eglandular and glandular hairs, the latter sometimes mainly towards base. Corolla infundibular, 26–33 mm long, white (but see note), eglandular-pubescent externally; tube with cylindrical basal portion 7–10 × 1.7–2 mm, expanded throat 14–17 mm long, 6.5–7 mm wide towards mouth (ratio of cylindrical tube: expanded throat 0.5–0.6: 1), lobes subequal, c. 6–8 mm long, rounded. Stamens included within corolla throat, inserted c. 11.5 mm from base of tube, pairs markedly didynamous; filaments of anterior stamens free for 6–7 mm long, those of posterior stamens 3.6–4 mm long, glabrous, filament curtain extends to near base of corolla tube; anthers ± 2–2.3 mm long, those of posterior stamens marginally smaller. Pistil drying brown, ovary eglandular-puberulous, hairs pale; style shortly pubescent; stigma with anterior lobe 0.9–1.5 mm long, posterior lobe not or barely developed. Capsule stipitate, 13–16 mm long including stipe ± 7 mm long, finely eglandular-puberulous, 4–12-seeded (fide Vollesen, 2013; R. praetermissa s.l.); seeds, c. 2.5 × 2.2 mm, with dense hygroscopic hairs along marginal rim, elsewhere glabrous or with sparse minute spreading hairs.

Vernacular name and uses: At Buko-Zau, the leaves are used as a food by local communities, under the local name “mupoko” ( Missão de Estudos Florestais a Angola 628).

Flowering & fruiting: The single record from Angola was recorded to be flowering and fruiting in June which is early in the dry season in this region.

Habitat: The single Angolan collection of this species is from moist forest at ± 100 m elevation. More generally, R. praetermissa is found in a wide range of habitats from grassland and woodland through to forest margins, and in the southern part of its range often grows on termitaria ( Vollesen, 2008, 2013).

Distribution: Widespread in western and central Africa, extending from Senegal and Mauritania, east to South Sudan and south to Angola, Zambia, Malawi and Mozambique; it also occurs in southern Arabia. In Angola it occurs only in the Maiombe region of Cabinda province.

Specimens examined: ANGOLA, Cabinda prov., Maiombe, Buco Zau, Fazenda Caio, fl. & fr., 08.06.1960, M.E.F.A. [Missão de Estudos Florestais a Angola] 628 (LISC). CONGO (BRAZZAVILLE), Kouilou region, Goumina (Mayombe), fl. & fr., 28.11.1990, I.F. la Croix 4961 (K). D. R. CONGO, Kongo Central prov., Léopaldville, Boma, Luki INEAC, fl. & fr., 1959, J. Dubois 389 (K).

Conservation status: A widespread and locally common species in a range of habitats, this species is considered to be of Least Concern (LC) globally. However, in Angola it is only known from the forests of Cabinda. Large areas of these forests are now included within the 1,930 km 2 Maiombe National Park, gazetted in 2011, as part of the Mayombe Forest Transfrontier Initiative. The park is still inhabited by 56,000 residents, many of whom continue to engage in unsustainable slash-and-burn subsistence or small-scale commercial agriculture ( Ron, 2020). Further, Buco-Zau is an expanding urban settlement with nearby mining activities and associated infrastructure and transport routes, and there is continued logging activity in Cabinda, both legally and illegally (Romeiras et al., 2014). All of these factors impact the forest through clearance, degradation and fragmentation. The National Park has very limited resources with which to manage or mitigate these threats ( Ron, 2020). Hence, Ruellia praetermissa may be nationally threatened. A management plan for the park was established in 2019 and supported by wide stakeholder engagement including at the community level and it is hoped that this will result in more sustainable land use practices in the future ( Ron, 2020).

Notes: The cited specimen from Angola matches material from the Maiombe (or Mayombe) hills of adjacent D. R. Congo and Congo (Brazzaville), for which the specimens seen are cited above, which has been proposed as a distinct species by Dominique Champluvier, namely Ruellia mayombensis Champl. ined. In an unpublished manuscript seen by the current authors, Dr. Champluvier noted that the Maiombe specimens differ markedly from other specimens of R. praetermissa studied in preparation for the account of Acanthaceae for Flore d’Afrique Centrale, noting (1) the more slender and longer petioles; (2) the leaf indumentum being diplotrichous with numerous short thin hairs mixed with scattered much longer stout multicellular hairs ( vs. leaves with only scattered stout multicellular hairs); (3) the smaller, straw yellow-coloured capsules which are densely pubescent ( vs. capsules rusty brown, glabrous); and (4) the uniformly white corolla [colour stated on four out of eight specimens seen] ( vs. blue-mauve or pink in R. praetermissa ). She also noted the strict association of the Maiombe taxon with rainforests, whilst R. praetermissa grows in a wider range of habitats, including moist forests but more frequently in wooded grasslands, dry forests, woodlands, termitaria and disturbed habitats (D. Champluvier, unpubl. data). The Angolan specimen matches all of these characters except for the diplotrichous leaves, as it has long multicellular hairs only.

There is no doubt that there is considerable variation within Ruellia praetermissa s. l. and that the Maiombe populations form a somewhat discrete morphological variant. The lectotype of R. praetermissa from South Sudan ( G. Schweinfurth 2155) and similar specimens from across much of the range of the species bear glabrous, often rich-brown capsules very similar to those of R. patula (and they also typically have short calyx lobes similar to those of R. patula ). However, plants similar to those from the Mayombe populations are found elsewhere in the range of R. praetermissa , most notably in Zambia ( e. g., W.L. Astle 4516 and 5557 from the Luangwa Valley, both K!), where some specimens have straw-yellow, puberulous capsules as in Maiombe and have similarly long-petioled leaves ( Vollesen, 2013). These populations have blue to pink flowers and have only scattered long hairs on the upper surface of the leaves but are otherwise a good match for the Maiombe material. Furthermore, some of the characters noted as diagnostic by Dr. Champluvier are not consistent. In particular, flower colour varies within R. praetermissa and includes white forms ( Vollesen, 2013), although these are admittedly rare. Similar variation in flower colour is also seen in both R. patula and R. prostrata (see Notes to those species), indicating that flower colour may not be diagnostic within Ruellia sect. Dipteracanthus . Secondly, capsule colour also shows some variation, with occasional straw-yellow or yellow-green, glabrous capsules noted in R. praetermissa ( e. g., H. M. Richards 19491 from Mbala district, Zambia, K!) which otherwise looks similar to specimens with puberulous fruits. Hence, the variation within R. praetermissa s. l. is complex and we do not feel that the Maiombe populations can be unambiguously separated as a distinct species based on morphological evidence alone. The description above nevertheless focusses on the Maiombe populations in case R. mayombensis is formally described in the future.

There is little doubt that Ruellia praetermissa is closely related to both R. patula and R. prostrata and the populations pertaining to all three may not always be fully differentiated at present. In the study area, they are very easily separated by the characters listed in the key, but these may not hold up across the full ranges of the three species. Vollesen (2008, 2013) notes that R. praetermissa is day-flowering whilst the other two species apparently drop their flowers early in the morning and so are likely to be night-flowering. However, our observations from Angola and Namibia suggest that both R. patula and R. prostrata can be day-flowering.

3. Ruellia patula Jacq., Misc. Austriac. 2: 358. 1781; C.B.Clarke in Fl. Trop. Afr. 5: 45. 1899, pro parte; Hiern, Catalogue Afr. Pl. coll. Friedrich Welwitsch 1853-1861, Dicotyledons, part IV: 808. 1900; Makholela in Figueiredo & Smith, Pl. Angola: 24. 2008; Vollesen in Fl. Trop. E. Afr. Acanth. (Part 1): 207. 2008 & in Fl. Zambes. 8(5): 138. 2013. Type: Cult. in hort. Vienna from seeds from INDIA; probably not preserved ( fide Vollesen, 2008). FiGS. 1d,G & 3

Flowering & fruiting: This species has been recorded as flowering and fruiting in Angola between November and June, corresponding to the rainy season and the onset of the dry season.

Habitat: Occurs in a variety of open to more shaded habitats, generally in dry to mesic areas, often persisting in disturbed areas such as roadside scrub and field margins; 5–1500 m elevation.

Distribution: Widespread in tropical and southern Africa, Arabia, and the Indian subcontinent. In Angola it is widespread in the west occurring in Benguela, Cuanza Sul, Cunene, Huíla, Luanda and Namibe provinces.

Specimens examined: ANGOLA, Benguela prov., Elephants’ Bay, fl., 1842, Curror 21 (K); andados 20 km de Chongoroi para Benguela , fl. & fr., 16.11.1955, E.J. Mendes 620 ( LISC, LUBA digital image) . Cuanza Sul prov., Estrada Cachoeiras–Bimbe ao km 8 do lado direito, fl., 19.04.1967, B. Teixeira et al. 11301 ( LISC) ; Aeroporto de Novo Redondo , fl. & fr., 12.04.1967, B. Teixeria et al. 11383 ( LISC) . Cunene prov., Cahama, junto da jangada no rio Caculovar , fl., 10.02.1956, E.J. Mendes 1682 ( LISC, LUBA digital image) . Huíla prov., Mossamedes, Shella Mountains [Serra de Chela], fl. & fr., 1920, s.coll. [? J. Gossweiler] s.n. (K); Ganguelas , Vila Artur de Paiva [Cuvango], Missão , vale do Cuvango , fl., 09.04.1960, E.J. Mendes 3518 ( LUBA) . Luanda prov., Loanda, fr., s.d., F. Welwitsch 5069 (BM, K, LISU digital image), Ibid., F. Welwitsch 5121 ( BM, LISU digital image); Ibid., F. Welwitsch 5139 ( BM, LISU digital image); distr. Loanda, pr[ope] Maianga do Povo , fl. & fr., 01.1858, F. Welwitsch 5127 (BM, K, LISU digital image); distr. Loanda , prope Teba et Boa Vista , fl. & fr., 06.1858, F. Welwitsch 5186 ( BM, LISU digital image); Loanda , fr., 1903, J. Gossweiler 370 (BM, K); Musseque , Ponta das Lagostas, fl. & fr., 14.03.1937, A.W. Exell & F.A. Mendonça 7 ( BM) . Namibe prov., near km 108.5 on the Mossamedes Railway, fr., 29.04.1909, H.H.W. Pearson 2830 (K); MoÇamedes, perto da encruzilhada Bruco–Bumbo–AssunÇão , fl., 01.12.1955, E.J. Mendes 955 ( LISC) ; MoÇamedes, Caluungo , entre a casa e o rio, fl., 16.11.1962, A. Figueira de Sousa 247 ( LUBA) ; MoÇamedes, de Caluundo para o Chingo , fl., 21.11.1962, C. Henriques & F. Moreno 100 ( BM) ; between Bibala and AssunÇao , fl. & fr., 10.04.2017, E. Tripp & K. Dexter 6915 ( COLO, K, LUBA) .

Conservation status: A widespread and often locally abundant species, tolerant of disturbance, here assessed as of Least Concern (LC).

Notes: For a full description, bibliography and synonymy of Ruellia patula relevant to continental Africa, see Vollesen (2008, 2013). This species is highly variable across its broad range and only plants from Angola and immediately neighbouring areas were considered when preparing the key above. Elsewhere within its range, the length of the corolla tube, and in particular the cylindrical basal portion, can vary considerably and the cylindrical portion can be longer than the expanded throat, as is the case in many populations in the southeast of its African range ( Vollesen, 2013). It is possible that several taxa, infraspecific or separate species, may be involved in this single name following additional study. However, the Angolan material is fairly uniform morphologically.

In Angola, the flowers are typically pink to purple, and hence often separable from Ruellia prostrata where the flowers are usually white in Angola (see above), but white-flowered forms are common elsewhere in the range of R. patula s. l. In addition, in Angola the corollas are 15–24 mm long with the cylindrical portion of the tube only 3.8–6 mm long, whilst in R. prostrata the corollas are 24.5–31.5 mm long with the cylindrical portion of the tube 6.5–9 mm long, but these differences do not hold up in other parts of the ranges of these species where they are sympatric.

Given that there appears to be no original material for Ruellia patula , this name requires neotypification. However, we refrain from doing so until a full revision of this complex species is carried out.

4. Ruellia togoensis (Lindau) Heine in Kew Bull. 16: 181. 1962; Heine in Fl. W. Trop. Afr. 2: 397. 1963. Dischistocalyx togoensis Lindau in Bot. Jahrb. Syst. 33: 188. 1902. Stenoschista togoensis (Lindau) Bremek. in Bot. Jahrb. Syst. 73: 148. 1943. Type: TOGO, Maritime region, prope Lomé, fl., 10.1900 [ fide Lindau, 1902], O. Warnecke 264 (holo P [P00436147 digital image!]; iso BR [BR0000006293406 digital image!], HBG [HBG502248 digital image!], K [K000394007!]).

Ruellia ardeicollis Benoist Bull. Soc. Bot. France 61 (Mém. 8e): 278. 1917. Lectotype (designated here): CÔTE D’IVOIRE, district du Woroba, vallée de la Moyenne Sassandra: Orodougou, entre Sifié et Séguéla, fl., 02.06.1909, A. Chevalier 21816 (P [P00436144 digital image!]; isolecto K [K000394006!], P [P00436145 digital image!]). Residual syntype: CÔTE D’IVOIRE, district du Lacs, Morénou, entre Anoumaba et Sahoua, fl., 23– 24.11.1909, A. Chevalier 22436 (P [P00436146 digital image!]). FiGS. 1e,f & 2

Slender perennial herbs, decumbent or erect, 10–70 cm tall, often rooting along trailing basal stems; young stems 4-angular, sulcate in dry state, with sparse to more numerous spreading-antrorse somewhat hispid hairs or these rarely shorter and appressed-antrorse, (0.2–) 0.5–0.8 mm long, and with few to more numerous wispy glandular hairs 0.5–1.3 mm long; mature stems less angular and can be glabrescent. Leaves on petioles 5–27 mm long, with antrorse somewhat hispid hairs mainly above and with shorter antrorse hairs in the adaxial groove; blade ovate, 36– 100 × 14–52 mm (l: w ratio 1.7–2.6: 1), base broadly cuneate or shortly and broadly attenuate, margins entire, apex (sub-)attenuate, surfaces with somewhat hispid eglandular hairs, evenly distributed on upper surface, most dense along main veins beneath and along margin, at first numerous but rather sparse at maturity, often with few wispy glandular hairs along margin towards base, midvein with short antrorse hairs on upper surface; cystoliths numerous, linear; lateral veins 4–6 per side. Inflorescences axillary in distal leaf axils, each 1(–2)-flowered, opposite, sessile; bracteoles (oblong-)oblanceolate to spathulate, 2.5–13 × 0.7–3.3 mm, indumentum as leaves. Calyx 5–9.5 mm long, fused at base for 1.3–2.2 mm; lobes linearlanceolate, 0.5–0.8 mm wide, each with prominent midvein, external surface with short ± ascending eglandular hairs along margins and sometimes along midveins of lobes, rarely with few scattered glandular hairs; cystoliths very numerous and giving calyx a glaucous appearance. Corolla salverform, 42–55 mm long, white or very rarely pale lilacpurple, retrorsely eglandular-pubescent externally; tube with cylindrical basal portion 26–33.5 × 1–1.3 mm, expanded throat 9–12 mm long, 5–9 mm wide at mouth (ratio of cylindrical tube: expanded throat 2.3–3.5: 1), lobes subequal, 6.5–10.5 × 6.8–10.5 mm, rounded, sometimes with shallowly emarginate centre. Stamens included within corolla throat or anthers held at mouth, inserted c. 12 mm from base of tube, pairs didynamous; filaments of anterior stamens free for 6.8–7.5 mm long, those of posterior stamens 5–5.2 mm long, glabrous; anthers of anterior stamens ± 1.9–2.2 mm long, those of posterior stamens ± 1.7–2.1 mm long. Pistil drying brown, ovary densely eglandular-puberulous, hairs pale brown; style shortly pubescent; stigma with anterior lobe ± 1 mm long, posterior lobe not or barely developed. Capsule stipitate, 19–24.5 mm long including stipe 9–10 mm long, retrorsely eglandular-puberulous, 8–12-seeded; seeds, c. 2.8 × 2.5 mm, with dense hygroscopic hairs along marginal rim, elsewhere glabrous or with sparse minute spreading hairs.

Flowering & fruiting: From the limited data available for Angola, this species has been recorded to flower in the rainy season between December and April.

Habitat: “Scrub forest” ( Dawe 381); seasonally moist forest with Khaya anthotheca (Welw.) C.DC. ( Meliaceae ) and Milicia excelsa (Welw.) C.C.Berg ( Moraceae ); c. 380–1160 m elevation.

Distribution: Widespread but scarce in western and southwestern tropical Africa, occurring in Côte d’Ivoire, Ghana, Togo, Benin, Nigeria, D. R. Congo and Angola. In Angola, it is recorded from Cuanza Norte, Malange and Namibe provinces (see Notes).

Specimens examined: ANGOLA, Cuanza Norte prov., close to Cambondo village, fl., A. Martins (photo record). Malange prov., Casal , fl., 18.04.1922, M.J. Dawe 381 (K) . Namibe prov., MoÇamedes, Caluungo , junto as rio, fl., 16.12.1962, A. Figueira de Sousa 249 ( LUBA digital image) . BENIN, Mono department, Logdo , 11 km NE Athiémé, fl., 25.02.1965, J. Raynal & A. Raynal 13516 (P digital image) . CÔTE D’IVOIRE, district du Lacs, Orumbo Boka , fl., 05.04.1967, Y. Sell 547 (P digital image). District de la Vallée du Bandama, c. 70 km W of Bouaké, Forêt Classée Matiemba , c. 25 km S of Béoumi, 5 km SE of Ando, fl. & fr., 27.05.1963, W.J.J.O. de Wilde 95 ( WAG digital image). D. R . CONGO, Kongo-Central district, Koma, village de Kalamu, fl. & fr., 11 [Nov.], without year, A. Dacremont 111 (BR digital image, K); Moanda , fl. & fr., 06.1903, J. Gillet 3248 ( BR digital image); Jardin Agronomique de Kisantu , fl. & fr., 16.08.1930, H. Vanderyst 24647 ( BR digital image); Ibid., fl., 02.1932, H. Vanderyst 28538 ( BR digital image) . GHANA, Ashanti region, top of Ejura Scarp, fl. & fr., 10.12.1953, J.K. Morton in GC 9798 (K, WAG digital image); Agogo, fl., 10.04.1954, C.D. Adams 2635 (K). Bono region, mile 95.5 on Sunyani–Berekum road, fl., 19.12.1954, C.D. Adams 2776 (K); Mpameso Forest Reserve 20 miles S of Dormaa – Ahenkro, W Ashanti, fl., 23.12.1954, C.D. Adams 2958 (K). Bono East region , Brong-Ahafo Region, Nkuranza dist., Boabeng-Fiema Monkey Sanctuary , fl., 05.12.1990, S.J. Manktelow et al. 111 (K) . Eastern region, Koforidua road, Begoro, fl., 01.11.1953, J.K. Morton A33 (K, WAG digital image); Ampam , Kwahu , fl., 22.12.1957, C.D. Adams 5026 (K) . NIGERIA, Ondo state, Ikare dist., Iha–Ipe Akoko , fl. & fr., 16.05.1978, B.O. Daramola & P.C. Ihe BO.451 ( FHI digital image) .

Conservation status: This is widespread species with an EOO in excess of 2,000,000 km 2 across west and west-central Africa. However, it is apparently scarce and is absent from large parts of this range, with fewer than 20 known locations. Further, it is almost certainly in decline due to widespread destruction of its seasonally wet forest habitat. Therefore, whilst it is likely to qualify as of Least Concern (LC) under IUCN criterion B, it would nevertheless be desirable to gather more data on current range and population size.

Notes: This species appears to be associated with seasonally moist semi-deciduous forests in west and west-central Africa, apparently being absent from the permanently wet forests of Lower Guinea and much of the Congo Basin. The description above covers specimens from across the range of this widespread but scarce species; as a result, all specimens seen are cited above, not just those from Angola. Despite the wide range and large disjunction between specimens from the northern part of the range in Upper Guinea ( Côte d’Ivoire to Nigeria) and those from the southern part of the range south of the Congolian region (D.R. Congo and Angola), the plants are remarkably consistent morphologically with only minor variation. The flower colour is usually white, but de Wilde 95 (WAG) from Côte d’Ivoire is recorded as having “pale purplish-lilac” flowers.

The specimen A. Figueira de Sousa 249 at LUBA has only been seen as a digital image by the first and third author; it appears to be a close match for this species, but the locality in southern Angola is rather out-ofrange for the typical distribution of this species, as it is otherwise found only in the north. It is included tentatively here but it would be ideal to examine this specimen more closely to make sure it belongs to the species.

Ruellia togoensis is remarkable amongst palaeotropical Ruellia for being the only species known to lack the coarsely reticulate pollen exine that is typical for the genus. Instead, it has a clavate exine and a densely granulate surface (Furness & Grant, 1996). Different pollen types are rare elsewhere in Ruellia although are notable in the sect. Blechum (P.Browne) E.Tripp & T.F.Daniel of the New World, where species have 3-syncolporate pollen grains ( i. e., the apertures meet at the poles), often and with a finely to coarsely reticulate exine ( Tripp et al., 2009; Manzitto-Tripp & Daniel, 2023), and so differing from the typical 3- (or 5-)porate spherical grains with coarse exine in Ruellia . Ruellia togoensis would otherwise fit well within sect. Dipteracanthus , most notably in having stipitate capsules with seeds with the hygroscopic hairs concentrated along the marginal rim. However, given the odd pollen type, this species should be a priority for future inclusion in molecular phylogenetic studies to confirm its infrageneric placement.

Typification: A lectotype is chosen for Ruellia ardeicollis from amongst the original syntypes, with the P sheet of Chevalier 21816 being selected as it is the most informative specimen amongst the original material.

5. Ruellia currorii T.Anderson in J. Proc. Linn. Soc., Bot. 7: 24. 1863; C.B. Clarke in Fl. Trop. Afr. 5: 48. 1899; Makholela in Figueiredo & Smith, Pl. Angola: 24. 2008. Type: ANGOLA, Benguela prov., Elephants’ Bay , fl., 1842, Curror in herb. Hooker 17 (holo K [K000394002!]). FiGS. 1h–j & 4

Shrubs 40–100 cm tall; young stems grey-green, only slightly angular, with numerous shallow longitudinal ribs, densely eglandular-puberulent, sometimes also with interspersed glandular hairs of ± equal length, softly velutinous to the touch; mature stems becoming woody, terete, grey or sandy-coloured, indumentum persistent. Leaves on petioles 7.5–17 mm long, indumentum as young stems; blade ± broadly ovate, 19–39 × 13–20 mm (l: w ratio 1.1– 1.5(–1.95): 1), base shallowly cordate or truncate, margins entire or shallowly repand, apex obtuse to bluntly acute, surfaces eglandular-puberulous, hairs widespread or mainly along margin and veins beneath at maturity, with minute short-stalked glandular hairs beneath and sometimes also along margin; cystoliths numerous, short and of unequal length; lateral veins 3–6 per side. Inflorescences axillary in distal leaf axils, each 1–3-flowered; peduncle conspicuous, sometimes curved-ascending, 5–52 mm long, secondary branch(es) if present 8–21 mm long, eglandular-puberulous with slightly retrorse hairs, often also with few to numerous short glandular hairs; bracteoles spathulate to subulate, 2.5–8.5 × 0.7–2.3 mm, can be caducous; flowers sessile or with pedicels to 2.5 mm long. Calyx 11–19 mm long, proximal +/- 1/3 fused by hyaline tissue between lobes, extending somewhat in fruit; lobes narrowly lanceolate, 1.2–1.4 mm wide, external surface densely glandular-pilose to -villose, hairs yellowish to cream-coloured, 0.8–1.5 mm long, shortening towards lobe apices where glandular-pubescent, also with interspersed eglandular hairs mainly along margins. Corolla broadly infundibular, 48–51 mm long, tube pale green-yellow externally, throat white, limb purple or white, glandular-pilose to sparsely so externally; tube with cylindrical basal portion 13–18 × 2.2–3.3 mm, broadly expanded portion 23–29 mm long, 17–18 mm wide at mouth (ratio of cylindrical tube: expanded throat 0.55–0.9: 1), lobes subequal, 8.5–10.5 × 13.5–15 mm, broadly rounded with shallowly emarginate centre. Stamens included within corolla throat, pairs didynamous; filaments of anterior stamens free for ± 12.5 mm long, those of posterior stamens 7 mm long, glabrous; anthers of anterior stamens ± 5 mm long, those of posterior stamens ± 4.5 mm long. Pistil drying brown, ovary minutely glandular; style shortly pubescent, with or without scattered subsessile glands; stigma with anterior lobe 3.5–5 mm long, can be inrolled in dry material, posterior lobe not or barely developed. Capsule narrow oblong-ellipsoid with short, poorly differentiated basal stipe, 21.5–30 mm long, with few minute glandular hairs towards apex, (10–)12–16(–18)-seeded; seeds ± 2.2 mm in diameter, with dense hygroscopic hairs along marginal rim, elsewhere glabrous.

Flowering & fruiting: This species has been recorded to flower and fruit between January and August; rainfall is intermittent and unpredictable within its range hence the relationship to rainfall patterns is unclear.

Habitat: Recorded from sparse desert shrubland and plains, Commiphora-Acacia-Rhigozum scrub and along dry stony, gravelly or sandy riverbeds; 0–650 m elevation.

Distribution: Restricted to the Namib Desert of southwest Angola ( Benguela and Namibe Provinces) and northwest Namibia ( Kunene Region).

Specimens examined: ANGOLA, Benguela prov., Equiminha, fl., 05.2022, A. Martins (photos https:// biodiversidadeangola.com/plants/specimen/173). Namibe prov., Pediva, near Porto Alexandre, fl., 27.06.1954, R. Brain s.n. (PRE digital image); MoÇamedes, Pediva, st., 01.06.1965, R. Correia 2917 (LUBA digital image); c. 55.8 km ESE of Tombua, fl. & fr., 19.01.2009, S.P. Bester 9161 (PRE digital image); Omauha Rest Camp,± 60km from Iona National Park, fl.&fr., 20.01.2009, F.Crawford FC406(K,LUBA, PRE digital image); Omahua Lodge, fl. & fr., 20.01.2009, A. Hankey & K. van der Walt 2715 (PRE digital image) – see also iNaturalist observation: https:// www.inaturalist.org/observations/19967714; Iona National Park, fl., 04.2018, C. Neto (photos https:// biodiversidadeangola.com/plants/specimen/173); 59 km S of Virei en route to Pediva, fl. & fr., 16.04.2017, E. Tripp & K. Dexter 6958 (COLO, K, LUBA). Namibe / Cunene prov., Coroca [R.] to Palmfontein, fl., 24.08.1899, H. Baum 13 (Z digital image). NAMIBIA, Kunene region, Kapupa valley, fl., 16.08.1956, R. Story 5836 (K, PRE digital image); about 8 miles up Kapupa R. (Otjihipa Mountains), fl. & fr., 07.07.1959, Davies et al. 55 (PRE digital image).

Conservation status: This is a very localised species from the northernmost extent of the Namib Desert, with an EOO of 29,160 km 2 and an AOO of 44 km 2 based on known occurrence data. It has been noted as locally fairly frequent ( Story 5836) to occasional or uncommon ( S.P. Bester 9161; F. Crawford FC406). Several of the known subpopulations are within the Iona National Park of Angola. This site experienced degradationduringandafterthewarofindependence (1961–1974) and the subsequent Angolan civil war (1975–2002), with problems of illegal hunting and increased settlement and associated domestic livestock numbers within the park, putting pressure on the natural environments. However, since 2019 the park has been managed by African Parks in conjunction with the government, and considerable effort has been put into both ecological and socioeconomic sustainability ( African Parks, 2023). Further north, this species is probably underrecorded in the largely unbotanised Namib between Iona and Equiminha, hence the AOO is likely to be considerably higher than currently recorded, and as the human population is rather sparse across much of this area, threats are unlikely to be severe. In Namibia, it is highly localised but the localities are remote and unlikely to be threatened, hence in the National Red Data Book of Namibian Plants ( Loots, 2005) the species was assessed naturally as “Rare”, i. e., meeting one of the agreed criteria for rarity ( SANBI, 2023), but not exposed to any direct or plausible potential threat and so not qualifying for a category of threat under the five IUCN criteria. Globally, it has been assessed as of Least Concern (LC) by Craven (2004) due to the lack of current or plausible threats, although that assessment was based upon a smaller dataset with an EOO of 1250 km 2 cited. We concur with this assessment here. However, in the longer term, climate change, in particular prolonged drought, may impact this species given its small range in what is already a harsh environment.

Notes: Tripp and Darbyshire (2017) earlier noted the challenge in placing this species to section within Old World Ruellia . The general facies of the plant, including the broadly ovate leaves and pedunculate cymes are similar to members of sect. Discifolia but the long slender capsule and seeds with hygroscopic hairs confined to the rim suggest placement in sect. Dipteracanthus and Tripp and Darbyshire (2017) placed it tentatively in that latter section on that basis. However, this species should be a priority for inclusion in future molecular studies in Ruellia .

This is one of a number of endemic Acanthaceae species that occur in the arid northernmost portion of the Kaokoveld centre of plant endemism in the border region between Namibia and Angola. This area is particularly important for diversity in the genera Petalidium Nees ( Tripp et al., 2017; Loiseau et al., 2023; Dexter et al., 2023), Barleria L. including the recently described Barleria deserticola I.Darbysh. & E.Tripp ( Darbyshire et al., 2019, 2021), Pogonospermum Hochst. (formerly members of Monechma Hochst.) including P. eriniae (I.Darbysh.) I.Darbysh. & Kiel (Darbyshire & Goyder, 2019; Darbyshire et al., 2020, 2022), and Blepharis Juss. ( Vollesen, 2000) . Other endemic Acanthaceae of this region include Rhinacanthus kaokoanus K.Balkwill & S.D.Will. ( Balkwill, 1995; Darbyshire et al., 2018) and the monospecific genus Mcdadea E.Tripp & I.Darbysh. ( Tripp & Darbyshire, 2020) .

6. Ruellia angolensis I.Darbysh. & E.Tripp , sp. nov. FiGS. 3 , 5A–k & 6

Ruellia angolensis is unlikely to be confused with any other species of continental African Ruellia , by the unique combination of densely pilose to villose stems, broadly infundibular white corolla, 4 subequal stamens, conspicuously 2-lobed stigma and broadly obovoid capsule with seeds with hygroscopic hairs across the surface. It superficially resembles Ruellia congoensis Benoist but differs most notably in having longer, linear calyx lobes ( vs. calyx lobes lanceolate, ± 9 mm long fide Benoist, 1916), the four stamens being subequal in length ( vs. stamens didynamous) and both lobes of the stigma being well developed ( vs. only one lobe of the stigma well developed).

Type: ANGOLA, Benguela prov., Membassoco (Capacca), Cubal, 18 km inland, fl. & fr., 11.1941, H.G. Faulkner A.14 (holo K [K001009372!]; iso BM [BM001124106!], PRE digital image!) .

Suffruticose perennial herbs, with few to numerous erect stems 10–30 cm tall arising from a short woody base (rhizome) with thick, fleshy roots; whole plant drying dark brown or green-brown; stems densely pilose to somewhat villose with patent long multicellular eglandular hairs 1.7–3.3 mm long, these (pinkish-)brown, lustrous, straight or the longest hairs becoming somewhat crisped, also with two opposite lines of inconspicuous short, ± retrorse eglandular hairs, distal portions of stems with interspersed minutely gland-tipped hairs, these shorter than or subequal to the long eglandular hairs. Leaves petiolate, petiole 3–14 mm long, pilose; blade ovate to ovate-elliptic or narrowly so, 4.3–8 × 1.9–5 cm (l: w ratio 1.4–3: 1), base rounded, obtuse or cuneate, margins entire or very shallowly crenate-serrate, apex acute, surfaces eglandular-pilose, densely so when young, hairs can be most dense on veins beneath, sometimes with few interspersed glandular hairs; cystoliths numerous; lateral veins 6–7 per side. Inflorescences axillary in distal leaf axils, single-flowered; peduncle 4–10 mm long, indumentum as young stems but with more numerous glandular hairs; paired bracteoles variable in shape and size, from oblong-elliptic to narrowly oblanceolate, 11–37 × 2–12.5 mm, those at distal-most nodes typically smallest and proportionally narrowest, those at lower fertile nodes can be leaf-like, indumentum as leaves; flowers sessile above bracteoles. Calyx divided almost to base into 5 linear lobes, 16–24.5 × 0.7–1 mm, eglandular-pilose and with some interspersed glandular hairs of similar length. Corolla 37–40 mm long, white, eglandular-pilose externally on distal portion of tube and on lobes, hairs longest on veins, proximal portion and internal surface of tube glabrous, lobes shortly glandular-pubescent internally; tube broadly infundibular, cylindrical basal portion 9.5–11 × 2.3–2.5 mm, expanded portion c. 12–16.5 mm long, 7.5–13 mm wide at mouth (ratio of cylindrical tube: expanded throat 0.6–0.9: 1), lobes subequal, c. 8.5–11.5 mm long, apices obtuse or rounded. Stamens included within corolla throat, pairs only very slightly unequal in length; filaments free for 4.8–5 mm long, glabrous; anthers 3.7–3.8 mm long. Pistil drying brown, ovary glabrous except at attachment of style; style shortly pubescent, hairs becoming sparser distally; stigma bilobed, only slightly unequal, anterior lobe 2.1–3.1 mm long, posterior lobe 1.8–2.2 mm long. Capsule obovoid above short basal stipe, 23.5–28 mm long including stipe c. 4.5–8 mm long, apex with a short beak to 1.5 mm long, surfaces glabrous; only immature seeds seen, 6(or more?)-seeded, with silky hygroscopic hairs across surface, most dense along margin.

Flowering & fruiting: From the limited data available, this species is recorded to flower and fruit in October and November, which corresponds to the early rainy season in western Angola.

Habitat: This species has been recorded from open miombo ( Brachystegia Benth. , Fabaceae ) woodland on stony soils and from bushland, and neighbouring young plantations of sisal; c. 1050–1300 m elevation.

Distribution: Restricted to western Angola, occurring in Benguela and Cuanza Sul provinces.

Etymology: This species is named for the Republic of Angola.

Specimens examined: ANGOLA, Cuanza Sul prov., Quibala, na estrada para Cariango, fl.* & fr., 25.10.1973, C. Henriques 1597 (LUBA); Quibala, entre Quibala e Condé, fl.*, 29.10.1973, R. Santos , C. Henriques & Daniel 3354 (LUBA digital image). [*- flower colour mentioned on the label of Henriques 1597 and Santos et al. 3354 but no flowers seen on the duplicates at LUBA].

Conservation status: This species is currently known only from the three cited specimens from west Angola, each considered to be a separate location within an EOO of approximately 4720 km 2. This falls within the range threshold for Endangered under criterion B1. It is considered likely to be scarce, given how few collections are known of what is a showy species. However, botanical exploration within its range has been very limited, and there is the additional complication that some herbarium records of this species may have been lost (see Materials and Methods). Miombo woodland habitat is threatened throughout this species’ range, with extensive woodland clearance noted through much of eastern Benguela and central Cuanza Sul provinces ( Mendelsohn, 2019). With regard to the three known locations for the species, Membassoco is on the EN110 road, the main route inland from Benguela towards Huambo, and there is now extensive agricultural land, with natural vegetation limited to the scattered rocky hills in this area. The areas around Quibala (to the west and east) are also heavily settled and farmed with some areas of commercial irrigation along the road towards Carianga ( Google Earth Pro, 2023). As this species has been recorded from areas around sisal plantations, it may be tolerant of some disturbance, but it is considered unlikely to persist in transformed landscapes. Using a standard 2 × 2 km grid cell size, this species has an AOO of 12 km 2, and, while almost certainly an underestimate, the actual AOO is considered likely to fall within the Endangered threshold of 500 km 2 under criterion B2 given the extent of habitat loss and fragmentation within its range. With a continuing decline in quality and extent of habitat, this species is therefore assessed as Endangered (EN) B1ab(iii)+B2ab(iii).

Notes: Based on the broadly obovoid capsule and seeds with hygroscopic hairs covering the surface, this species is here placed tentatively in sect. Discifolia as defined by Tripp and Darbyshire (2017). The leaves are less broadly ovate than in most species in that section, but additional morphological characters in support of placing this species in that section include the conspicuously bilobed stigma (present in several species in that section including in R. bignoniiflora ) and the pedunculate cymes. The sympatric species in sect. Discifolia , R. bignoniiflora and the newly described R. quipungoensis below, are unlikely to ever be confused with R. angolensis as these have very long cylindrical portions to the corolla tube (ratio of cylindrical tube: expanded throat length 1.8–3.45: 1) amongst other differences; see also Table 1 and the diagnosis section for R. quipungoensis below for additional differences to that species.

As noted in the diagnosis section, R. angolensis bears a superficial resemblance to the type specimen of Ruellia congoensis Benoist ( J. Dybowski 610, P [P00436136 digital image!]), a little-known species from Congo and Central African Republic. However, that species has much shorter and more lanceolate calyx lobes, didynamous stamens and only one lobe of the stigma is well developed, amongst other differences. The two species are not likely to be closely related, and R. congoensis is tentatively placed in sect. Dipteracanthus , possibly related to R. praetermissa .

7. Ruellia quipungoensis I.Darbysh. & E.Tripp , sp. nov. FiGS. 3 & 5L

Ruellia quipungoensis resembles Ruellia bignoniiflora but differs in the stem indumentum being a mixture of short white retrorse eglandular hairs and long patent lustrous yellow-brown eglandular hairs ( vs. shortly viscid glandular-pubescent and retrorse-puberulous, longer eglandular hairs often confined to older stems and much finer, white, not lustrous in R. bignoniiflora ); the bracteoles being narrowly oblong-elliptic to oblanceolate, 2–4 mm wide ( vs. ovate to broadly so, 5.5–16 mm wide); the calyx lobes being linear and densely long eglandular-pilose to -villose with interspersed shorter eglandular and few or no glandular hairs ( vs. lobes ligulate to lanceolate, shortly glandular-pubescent with longer eglandular hairs confined to margins and midveins of each lobe and to fused basal portion); corolla lobes being eglandular-pubescent externally ( vs. mixed glandular- and eglandular-pubescent); the stamens being somewhat more didynamous and with anthers 3.4–4.2 mm long ( vs. anthers 4.7–5 mm long); and the capsule being densely puberulous ( vs. capsule glabrous). It also resembles Ruellia angolensis in vegetative characters but differs in the narrow cylindrical portion of the corolla tube being c. 53.5 mm long and much longer than the expanded throat, ratio c. 3.45: 1 ( vs. cylidrical portion of tube only 9.5–11 mm long and shorter than the broadly expanded throat, ratio 0.6–0.9: 1 in R. angolensis ); the corolla lobes being glabrous internally ( vs. lobes shortly glandular-pubescent internally); the stamens being somewhat didynamous ( vs. anthers held at ± an equal height); and the capsule being densely puberulous ( vs. capsule glabrous).

Type: ANGOLA, Huíla prov., Quipungo, Morro do Posto Emissor, Mai-Mai , fl. & fr., 04.02.1966, R. Correia 3422/A (holo LISC [ LISC048174 !]; iso LUBA!) .

Perennial herbs, to 60 cm tall ( fide Correia 3422/A), basal parts not seen; stems eglandular-puberulous, hairs 0.2–0.3 mm long, white, retrorse to subappressed, and with numerous interspersed patent long multicellular eglandular hairs 2.5–3 mm long, these yellow-brown, lustrous, straight or somewhat curled towards tips. Leaves petiolate, petiole 5–14 mm long, indumentum as stems; blade drying dark green-brown above, paler and greyish beneath due to indumentum, ovate to narrowly so, 4.1–10.2 × 1.6–5.7 cm (l: w ratio 1.6–2.5: 1), base rounded, broadly obtuse or shallowly cordate, margins shallowly crenate-serrate, apex acute to bluntly so, upper surface eglandular-puberulous and with long yellow-brown, lustrous hairs 1.5–3 mm long as on stems, these becoming more numerous and shorter along margin where there are sometimes occasional interspersed short glandular hairs, lower surface pale-villose, largely obscuring surface; cystoliths numerous, linear, conspicuous on upper surface; lateral veins 5–9 per side. Inflorescences axillary in distal leaf axils, single-flowered; peduncle 1.5–3.5 mm long, indumentum as young stems, dense; paired bracteoles narrowly oblong-elliptic to oblanceolate, 11–21 × 2–4 mm, indumentum as leaves but more dense; flowers sessile above bracteoles.Calyx divided almost to base into 5 linear lobes, 17–24.5 × 1–1.2 mm in flower, extending up to 29 mm long in fruit, densely long eglandular-pilose to villose with hairs patent, typically 1–2 mm long, can be somewhat crisped, and with ± numerous interspersed short eglandular hairs, sometimes with very few interspersed glandular hairs. Corolla c. 82 mm long, colour unknown, eglandular-pubescent externally on distal portion of tube and on lobes, hairs longest on veins, proximal portion of tube glabrous, internal surface of tube unknown, lobes glabrous internally; tube with cylindrical basal portion c. 53.5 × 2.3 mm, expanded portion campanulate, c. 15.5 mm long, 12 mm wide at mouth (ratio of cylindrical tube: expanded throat 3.45: 1), lobes c. 13 mm long, rounded. Stamens included within corolla throat, didynamous, anthers of posterior pair overlapping those of anterior (longer) pair by c. half their length; filaments glabrous; anthers of longer stamens ± 4.2 mm long, those of shorter stamens 3.4−3.8 mm long. Ovary not seen; style shortly pubescent; stigma bilobed, longer lobe c. 0.8–1.8 mm long, curved in dry state, shorter lobe c. 0.6–1.1 mm long. Capsule only seen in immature state, broadly obovoid, 19 mm long, densely puberulous with fine pale hairs throughout; seeds not seen.

Flowering & fruiting: From the limited data available, this species is recorded to flower and fruit in February and March, which corresponds to the latter half of the rainy season in western Angola.

Habitat: Recorded from Brachystegia spiciformis Benth. ( Fabaceae ) (miombo) woodland on a hill ( Correia 3422/A; habitat not recorded on P. Pittard 39). Pittard lists the elevation of his collections as being 3000 ft, but Balombo is at c. 1200 m, hence the approximate elevation range is 1200–1320 m asl.

Distribution: Restricted to western Angola, occurring in Benguela and Huíla provinces.

Etymology: This species is named after the municipality of Quipungo in Huíla province of

Angola, from where the type collection is derived .

Specimen examined: ANGOLA, Benguela prov., Balombo , fl. 14.03.1938, P. Pittard 39 (BM [BM001124107]) .

Conservation status: This species appears to be scarce, currently known from only the two collections cited despite its large and showy flowers. However, botanical exploration within its range has been very limited, and there is the additional complication that some herbarium records of this species may have been lost (see Materials and Methods). Threats are widespread in its favoured habitats across its range, with extensive woodland clearance and high frequency of burning noted throughout much of northern Huíla and eastern Benguela provinces ( Mendelsohn, 2019).With regard to specific locations for this species, the area around the town of Balombo is extensively settled and farmed, although with some wooded hilly country to the southwest ( Google Earth Pro, 2023) where this species may persist. The area around Maimai (Chicócua) to the west of Quipungo in Huíla is now heavily transformed with little natural vegetation remaining. However, the Bicuar National Park is not far to the south of this area, and it is possible that this species occurs there where there are extensive areas of intact miombo habitat, but this would require confirmation. Using a standard 2 × 2 km grid cell size, this species has a known AOO of 8 km 2, and, while almost certainly an underestimate, the actual AOO is considered likely to fall well within the Endangered threshold of 500 km 2 under criterion B2 given the extent of habitat loss and fragmentation within its range. With two locations currently known and a continuing decline in quality and extent of habitat, this species is therefore assessed as Endangered (EN) B2ab(iii).

Notes: As with Ruellia angolensis above, this species is placed tentatively within sect. Discifolia based on the broadly obovoid capsule and bilobed stigma. It is similar to R. bignoniiflora in having a long-cylindrical corolla tube much longer than the limb, stamens included within the corolla throat and a bilobed stigma. However, the two species are readily separated by the characters listed in the diagnosis and key. In addition, they differ clearly where they are sympatric in Angola in R.bignoniiflora having a more pronounced widened corolla throat, the ratio of the cylindrical tube: enlarged throat being 1.8–2.1: 1, whilst in R. quipungoensis the throat is shortly campanulate and the ratio is c. 3.45: 1. However, in some populations of R. bignoniiflora from eastern Africa the throat can be less abruptly widened and the ratio of the tube to the throat has a much wider range, 1.7–4.9(–5.9): 1 (see note below under that species). In a vegetative state, Ruellia quipungoensis is most similar to R. angolensis , described above, but the corolla form is very different, and the fruits are puberulent rather than glabrous. See Table 1 for a comparison of these three species.

The measurements of the flowers in the description of Ruellia quipungoensis are based on the one mature flower observed, on Pittard 39, Hence they may not represent the full range of variation in flower size in this species.

8. Ruellia bignoniiflora S.Moore in J. Bot. 18: 198. 1880; C.B.Clarke in Fl. Trop. Afr. 5: 48. 1899; Hiern, Catalogue Afr. pl. coll. Friedrich Welwitsch 1853- 1861, Dicotyledons, part IV: 809. 1900; Makholela in Figueiredo & Smith, Pl. Angola: 24. 2008; Vollesen in Fl. Trop. E. Afr. Acanth. (Part 1): 204. 2008 & in Fl. Zambes. 8(5): 141. 2013. Dischistocalyx bignoniiflorus (S.Moore) Lindau in Engler & Prantl, Nat. Pflanzenfam. 4, 3b: 307. 1895. Dipteracanthus bignoniiflorus (S.Moore) Bremek. in Bot. Jahrb. Syst. 73: 149. 1943. Lectotype (designated by Vollesen, 2008): ANGOLA, Luanda prov., distr. Loanda, fl. & fr., 16.01.1859 [date on C sheet only], F. Welwitsch 5063 (BM [BM001124282!]; isolecto C [C10000052 digital image!], K [K000394003!], LISU[LISU223323, LISU223326–right-hand plant only; digital image!], P [P00436134 digital image!]) (see Notes). Residual syntypes: ANGOLA, Bengo prov., prope Banza do Regulo Quisembo, fl., 11.1853, F. Welwitsch 5126 (BM [BM001124111!], LISU [LISU223328 digital image!]); Luanda prov., distr. Loanda, fl., s.d., F. Welwitsch 5130 (BM [BM001124113!], LISU [LISU223327 digital image!]); Loanda, Praia de Zomba Grande, fl. & fr., 16/ 18.01.1859, F. Welwitsch 5202 (BM [BM000931018], LISU [LISU223324, LISU223325 digital image!]).

Ruellia megachlamys S.Moore in J. Bot. 32: 134. 1894; C.B. Clarke in Fl. Trop. Afr. 5: 48. 1899. Type: KENYA, Taita Taveta co., Teita Mts [Hills], Ndara Ndi , Ngurunga Kifaniko , fl., 1892–1893, J.W. Gregory s.n. (holo BM [BM000931019!]).

Ruellia cygniflora Lindau in Bot. Jahrb. Syst. 33: 186. 1902. Type: ETHIOPIA, Harari Regional State, Haqim [Gara Hakim], fl., 05.1900, H. Ellenbeck 963 (holo B† [ fide Ensermu, 2006]).

Ruellia oxysepala C.B.Clarke in Schinz, Denkschr. Kaiserl. Akad. Wiss., Wien. Math.- Naturwiss. Kl. 78: 439. 1906 syn. nov. Lectotype (designated here): MOZAMBIQUE, Tete prov., Boruma beim Sambesi, Mfidzi , fl., 1891, L. Menyhart 1076 [no. not listed in protologue] (WU [WU0043023 digital image!]; isolecto Z [Z-000000898 n.v.]). FiGS. 1k,L & 4

Subshrubs 60–80 cm tall, can be sprawling and wider than tall; leafy stems 4-angled, shortly patent viscid-glandular pubescent with hairs to 0.2 mm long, and with fine white retrorse eglandular hairs often concentrated in two opposite lines; mature stems becoming softly woody with pale grey or sandy-coloured bark, glandular hairs more sparse to absent, with few to very numerous long patent white eglandular hairs 2.7–5 mm long. Leaves on petioles 8–17 mm long, glandular- and eglandular-pubescent; blade ovate to broadly so, 32–43 × 19–37 mm (length: width ratio 1.1–1.7: 1), base rounded or shallowly cordate, margins entire, apex acute or shortly attenuate, surfaces pubescent, with mainly eglandular hairs above, these intermixed with ± numerous short glandular hairs beneath and along margins; cystoliths numerous, linear; lateral veins 4–5 per side. Inflorescences axillary in distal leaf axils, each single-flowered; peduncle 1.5–7.5(–18) mm long, indumentum as for young stems; bracteoles ovate to broadly so, foliaceous, 11–19.5 × 5.5–16 mm including short stalk, shortly glandular- and eglandular-pubescent; flowers sessile. Calyx 14–18 mm long in flower, extending somewhat up to 20.5 mm in fruit, fused at based for 1.7–2.8 mm; lobes ligulate, 1–2.2(–3.2) mm wide, external surface shortly glandular-pubescent and with longer fine eglandular hairs along margins and midvein of lobes, these more widespread on fused basal portion. Corolla salverform, 78–101 mm long, white with pale green-yellow tube externally, pubescent externally, hairs mainly eglandular on tube, mainly glandular on lobes; tube with cylindrical basal portion 41–61 × 2.2–2.5 mm, expanded throat 22–29.5 mm long, 8.5–12 mm wide at mouth (ratio of cylindrical tube: expanded throat 1.8–2.1: 1), lobes subequal, 11–17 × 11–12.5 mm, rounded or somewhat elliptic, with rounded or shallowly emarginate apex. Stamens included within corolla tube, pairs subequal in length; filaments free for 14.5–15.5 mm, pairs fused for 3–4 mm, largely glabrous except for few minute hairs towards base and apex; anthers 4.7–5 mm long. Pistil drying brown, ovary glabrous; style shortly pubescent; stigma 2-lobed, anterior lobe 2.6–3.5 mm long, posterior lobe 1.7–2 mm long. Capsule 19–24 mm long, obovoid with only very short stipe, glabrous; seeds discoid, 5.5–6.7 mm in diameter, with short hygroscopic hairs throughout.

Flowering & fruiting: This species has been recorded in Angola as flowering in November to April, with peaks in January and April, and fruiting in January to July. The flowering period corresponds with the rainy season.

Habitat: This species occurs in bushland, dry woodland and riparian areas, rock outcrops and sandy areas, typically in shade; c. 0–1050 m elevation.

Distribution: Widespread but scattered in tropical Africa, occurring in South Sudan, Ethiopia, Uganda, Kenya, Tanzania, Malawi, Mozambique, Zambia, Zimbabwe, Angola and Namibia. In Angola it is found in the west in Bengo, Benguela, Luanda and Namibe provinces.

Specimens examined: ANGOLA, Benguela prov., km 108.5 on the Mossamedes railway, fl. & fr.. 29.04.1909, H.H.W. Pearson 2846 (K); 18 km N of Campanda between Benguela and Lubango , fl. 08.04.2017, E. Tripp & K. Dexter 6909 ( COLO, K) . Luanda prov., distr. Loanda, fl., 1903, J. Gossweiler 371 (BM, K); Luanda, beira do C. F. no traÇado novo para o Congo , fl., 20.04.1958, R. Monteiro et al. 95D ( BM) ; Viana, fl., 12.2021, R. Ferreira (photo https://www.inaturalist. org/observations/102593651); Tombo, fl., 12.2021, A. Martins (photos https://biodiversidadeangola.com/ plants/specimen/172). Namibe prov., MoÇamedes, prox. de Camucuio, estrada de Lola , fl., 20.04.1958, R. Monteiro et al. 8397 ( LUBA) ; Bibala, fl., 15.01.2009, A. Hankey (photos https://www.inaturalist.org/ observations/19966164); road from Leba Pass to Caraculo , 4.1 km W of riparian tall mango forest, fl., 16.01.2009, P.J.D. Winter 7653 ( LUBA digital image) . NAMIBIA, Kunene region, nordwestlich von Otjitanda , [?]fr., 06.07.1969 [fl. in cult., hort. W. Giess, 20.12.1970 – 09.01.1971], P.G. Meyer 1281 ( WIND) .

Conservation status: A widespread but rather scattered species, it can nevertheless be locally frequent typically in habitats not favoured for agriculture. It is therefore assessed as of Least Concern (LC).

Notes: Ruellia bignoniiflora is a widespread but scattered species with several disjunctions in its range. There are three main population centres: (a) West Angola and just extending into northwest Namibia; (b) East Africa from Ethiopia through to central Tanzania; and (c) southeast Africa around the Zambesi Basin and into southern Zimbabwe. There is considerable morphological variation between and within these groups and the description above covers only the form from Angola and Namibia. This form ( R. bignoniiflora s. s.) differs from most of the eastern populations most notably in having a relatively short cylindrical portion of the corolla tube and a broader and more abruptly widened throat. In other populations, the cylindrical tube is 43–110 mm long but often over 60 mm long, the throat is 16–28 × 3.5–10 mm, and the ratio of the cylindrical tube: expanded throat is 1.7–4.9(–5.9): 1, but often 3: 1 or more. Eastern populations with a relatively short cylindrical portion to the tube are mainly found in Uganda (ratio 1.7–2.2: 1). These overlap with the Angolan populations in this character but differ markedly in having a narrow throat, sometimes only weakly differentiated from the cylindrical tube. Some of the populations from southeast Africa also have a somewhat shorter cylindrical portion of the tube (ratio 2–2.4: 1) but these populations differ from the Angolan material in having a somewhat more campanulate (less abruptly widened) throat and larger corolla lobes, as well as having conspicuously lanceolate calyx lobes. Occasional specimens with large corolla lobes are recorded elsewhere within its range, for example Y. E. Symes 541 (K) from Uganda. Several taxa may be involved but the variation is complex and requires further study and, ideally, supporting molecular data.

Welwitsch 5063, the lectotype of Ruellia bignoniiflora , is in fact a mixed collection. One of the sheets of this number at LISU [LISU223326] excluding the small right-hand plant, and most of one of the two sheets of this number at BM [BM001124281] are referrable to Ruellia prostrata . Therefore, it is necessary to clarify that Vollesen’s (2008) lectotypification of R. bignoniifolia is based on the second sheet at BM, BM001124282.

Typification: Ruellia oxysepala is newly synonymised here and the sheet of Menyhart 1076 at WU, which is available to view online and is an informative specimen, is selected as the lectotype.

Figures

FiG. 1. Angolan Ruellia species in situ: A-c. R. prostrata Poir.From Benguela prov.,Angola,collected as Tripp & Dexter 6911;c. From Ruacana Falls, Namibia, collected as Nyatoro et al. 32. d & G. R. patula Jacq.; From near Opuwo, Namibia, not collected. e & f. R. togoensis (Lindau) Heine;From near Cambondo village,Angola,not collected.h & i. R. currorii T.Anderson;From Equiminha,Angola,not collected;j. From south of Virei towards Pediva,Angola,collected as Tripp & Dexter 6958.k & L. R. bignoniiflora S.Moore;From north of Campanda,Angola,collected as Tripp & Dexter 6909 (photos a, b, j–l by E.A. Manzitto-Tripp,c, d, g by I. Darbyshire,e, f, h, i by A. Martins).

FiG. 2. Distribution in Angola of Ruellia prostrata Poir. (red circles), R. praetermissa Schweinf. ex Lindau (green triangle), and R. togoensis (Lindau) Heine (blue squares); note that the locality for the lattermost species in Namibe province could not be geolocated. Map created in QGIS Version 3.2 (QGIS.org 2023).

FiG. 3. Distribution in Angola of Ruellia patula Jacq. (black circles), R. angolensis I.Darbysh. & E.Tripp (green stars), and R. quipungoensis I.Darbysh. & E.Tripp (orange triangles). Map created in QGIS Version 3.2 (QGIS.org 2023).

FiG. 4. Distribution in Angola and neighbouring northwest Namibia of Ruellia currorii T.Anderson (blue triangles),and R. bignoniiflora S.Moore (red circles).Map created in QGIS Version 3.2 (QGIS.org 2023).

FiG. 5. Line drawings of Ruellia angolensis I.Darbysh. & E.Tripp (a–k) and R. quipungoensis I.Darbysh. & E.Tripp: A. Habit–flowering stem; b. Habit–fruiting plant with woody rootstock; c. Leaf–broader variant; d. Leaf margin–abaxial surface; e. Detail of stem indumentum; f. Flowering branch (based on painting by H.Faulkner);G. Edge-on view of glandularhairs on inner face of petal;h. Stamensin situ with style and stigma;i. Style and stigma,with enlarged detail of stigma (left);j. Bracteoles,calyx,ovary and style base;k. Capsule.L. Corolla.(a,b,d–k from Faulkner A.14;c from Henriques 1597;l from Pittard 39.Scale bars:single-line bar = 1 mm;graduated single-line bar = 2 mm and5 mm;double-linebar = 1 cm;graduated double-line bar = 5 cm.(Drawn by Andrew Brown).© the Board of Trustees of the Royal Botanic Gardens,Kew,reproduced with kind permission.

FiG. 6. Painting of Ruellia angolensis I.Darbysh. & E.Tripp by Helen Faulkner, with the illustrator’s annotations; reproduced from Helen Faulkner’s papers: FAU/1/6 (Sketchbooks) [drawing no. 318], Library and Archives,Royal Botanic Gardens, Kew.Reproduced with the kind permission of the Board of Trustees of the Royal Botanic Gardens,Kew.