Justicia cubangensis I.Darbysh. & Goyder, 2019

Darbyshire, I. & Goyder, D. J., 2019, Notes on Justicia sect. Monechma (Acanthaceae) in Angola, including two new species, Blumea 64 (2), pp. 97-107 : 100-101

Justicia cubangensis I.Darbysh. & Goyder , sp. nov. — Fig. 1 , 2a –c ; Map 1

Most similar to Justicia lolioides S.Moore but differs in the inflorescence having a puberulous indumentum of mixed eglandular and capitate-glandular hairs throughout (vs in J. lolioides inflorescences largely glabrous except for short ascending eglandular hairs along the margins of the bracts,bracteoles and calyx lobes); the calyx lobes being markedly longer than the subtending bracts and bracteoles (vs calyx ± equal in length to the bracts and particularly to the bracteoles); the corolla being finely eglandular-puberulous externally (vs corolla having numerous coarse bristly hairs on the lower lip externally in addition to being eglandular-puberulous); the anther appendage tapering to a single point at the apex (vs anther appendage bifid at the apex); and the capsule being eglandular-puberulous and ± 11 mm long (vs capsule es- sentially glabrous and 8–9 mm long). See Table 1. — Type: Goyder 8068 (holo K; iso CAS, INBAC,LUBA), Angola, Cuando Cubango Province,Cuchi River gorge (Cubango drainage),c. 7 km N of Cuchi, S14.58972 E16.90722, 1350 m, fl. & imm. fr., 28 May 2015.

Monechma lolioides sensu Moore (1930) 138, non (S.Moore) C.B. Clarke (1900) 218.

Etymology. The epithet ‘ cubangensis ’ denotes the Cubango River drain- age in which this species is found.

Erect or decumbent perennial herb,several annual,many-branch- ed stems 15 –65 cm tall from a woody base and rootstock, burnt stem bases from previous years’ growth sometimes persisting; stems quadrangular, two opposite sides with a central furrow, other two opposite sides either flat or with two shallow furrows, minutely retrorse-puberulous, hairs often more numerous on the two centrally furrowed sides, most conspicuous on lowermost internodes; nodal line with longer hairs. Leaves sessile, linear-lanceolate, longest blades 29–46 by 2.3–3.2 mm (length: width ratio 10–16: 1); base cuneate, margin entire, apex acute, surfaces with sparse and inconspicuous minute antrorse hairs mainly along margin; venation of 5 parallel veins, ± prominent particularly on adaxial surface. Inflorescences terminal and in upper axils, secund spikes 25–70 mm long; rachis (at least distally), bracts, bracteoles and calyces puberulous with mixed patent eglandular and capitate-glandular hairs; peduncle 3.5–12 mm long; each node of inflorescence single-flowered; bracts paired, minute, lanceolate or triangular, 1.8–4.8 by 0.7–1.5 mm in central portion of spike, dark green or purplish with paler base, midrib prominent; flowers sessile along rachis or lowermost flowers on a secondary peduncle to 5 mm long; calyx immediately subtended by erect paired bracteoles, lanceolate, 2.5–5.5 by 0.7–1.8 mm, pale yellowish cream distally, green towards apex, with pale hyaline margin. Calyx divided almost to base into five subequal linear-lanceolate lobes 6–7.5 by 0.7–1 mm in flower, extending somewhat in fruit when up to 9.5 by 1.6 mm, pale yellowish cream proximally and along margin, dark green to pinkish brown towards apex and along three parallel veins. Corolla 12–13 mm long, cream-white, pal- ate of lower lip pink with white veins in raised ‘herring-bone’ pat- tern, eglandular-puberulous externally mainly on lips; tube ± 7.5 mm long, cylindrical with ventricose floor ± 2 mm from base, pubescent internally at base of pouch and at base of rugula (stylar furrow); upper lip hooded, 5.5–6 mm long, apex shallowly bilobed; lower lip 5.2–6.2 mm long, reflexed distally at anthesis, apex 3-lobed, lateral lobes 1.2–1.5 by 1–1.1 mm, median lobe broader, 1.7–1.8 mm wide. Stamens inserted ± 5.5 mm from base of corolla tube; filaments white, 5.5–5.7 mm long; anthers at first green, turning dark brown, with thecae overlapping for ± half their length, oblique, upper theca 1–1.2 mm long, lower theca 1.2–1.4 mm long, with basal white subulate appendage 1–1.3 mm long, both thecae with few irregular rounded protru- sions (?glands) on inner surface. Ovary oblong-ovoid, 1.4–1.7 mm long, sparsely puberulous towards apex; style 9–10 mm long, pubescent in proximal half; stigma shortly bifid. Capsule only seen in immature state, 2-seeded, ± 11 mm long, shortly stipitate, eglandular-puberulous externally; immature seeds somewhat compressed, with smooth surface, glabrous.

Distribution & Ecology — Justicia cubangensis is found in Cuando Cubango and Huíla provinces of South-central Angola. It grows in open, sunny areas amongst grassland in open miombo woodland and open thicket on sandy soils, at ± 1350–1400 m elevation.

Conservation — This species is currently known only from three localities: the Cuchi River gorge, the vicinity of the municipality of Menongue and between Kuvango and Chipindo. Only a single plant was observed at Cuchi River gorge and Gossweiler recorded it as rare at Menongue, while Santos & Barroso recorded it as occurring in scattered tufts near Kuvango. This region of Angola has not been thoroughly botanized, and furthermore, many Angolan Acanthaceae collections were lost – presumed destroyed – during the civil war (see Darbyshire et al. 2019). It may therefore prove to be more widespread and/or locally common than current evidence suggests. The sites around Menongue are likely to have been impacted by the continued development of this town and the related expansion of agriculture in the surrounding area. The species may be tolerant to some degree of disturbance, however, as the Cuchi River gorge site was open and was possibly cleared from the surrounding miombo. In light of the incomplete evidence to date, Justicia cubangensis is provisionally assessed as Data Deficient (DD).

Additional specimens seen. ANGOLA, Gossweiler 2701 ( BM [ BM001135166 ],? K - see note), Menongue [Munongue],fl. & imm fr., 20April 1906 ; Gossweiler 3100 ( BM [ BM001135165 ], K), Ganguellas [Gunguellas], at Menongue [Mu- nongue], fl. & imm fr., April 1906 ; Santos & Barroso 2674 ( LISC *), Kuvango [Artur de Paiva], na estrada para Chipindo, fl., 10 May 1969 .

Notes — As noted in the Introduction, this species has previ- ously been confused with Justicia lolioides with which it shares narrow foliage and very slender, secund inflorescence spikes. However, it is easily separated by the characters listed in the diagnosis and in Table 1.

In addition to a duplicate of Gossweiler 3100 (incorrectly labelled as 30100), there is a second, unnumbered Gossweiler collection of this species at K with no locality data or date; it may be a duplicate of Gossweiler 2701.

The Cuchi River gorge, the type locality for this species, is a site of considerable botanical importance. It is one of the few places in the region where rock emerges from the overlying sand and is the locus classicus of succulents such as Aloe metallica Engl. & Gilg and Euphorbia faucicola L.C.Leach. In addition to the new species of Justicia , the 17 collections made at Cuchi River gorge in May 2015 included two new botanical records for Cuando Cubango Province, recorded below.A subsequent visit to the site in November 2016 revealed a species of Crotalaria L. that is also probably new to science.

Eriocaulon angustibracteum Kimp. (1994) 329 ( Eriocaulaceae )

Goyder 8071 (INBAC, K, LUBA, PRE), Angola, Cuando Cubango Province , Cuchi River gorge c. 7 km N of Cuchi, 28 May 2015 .

This is only the third record of this species from Angola. It was not recorded by Figueiredo & Smith (2008) in their checklist of Angolan plants, but a collection at K from Huambo province, near Ukuma [Cuma], made in 1959 (Damann in Herb. Hess 59/228) was redetermined as this species by Sylvia Phillips in 2016. It was also collected near Capaia, Lunda Norte, in 2013 (Goyder et al. 7163). The species is quite widely distributed and has been recorded from southern Tanzania, Zambia, the Ka- tanga region of D.R. Congo, and Cameroon ( Phillips 2010: 65).

Crepidorhopalon schweinfurthii (Oliv.) Eb.Fisch. (1989) 443; (1992) 130 ( Linderniaceae )

Goyder 8060 (INBAC, K, LUBA, PRE), Angola, Cuando Cubango Province , Cuchi River gorge c. 7 km N of Cuchi, 28 May 2015 .

This species was listed by Ghazanfar (2008) under the name Torenia schweinfurthii Oliv. ( Scrophulariaceae ), and within An- gola it has been recorded from Benguela, Huíla, Malange and Moxico provinces. It has a wide but scattered distribution from Mali to South Sudan, and south to Mozambique and Angola ( Darbyshire et al. 2015a: 329).

Figures

Map 1 Distribution map of Justicia cubangensis (●) and J. eriniae (■).

Fig. 1 Justicia cubangensis I.Darbysh. & Goyder. a. Habit, basal and distal portions of stems; b. mature leaf, abaxial surface; c. inflorescence; d. dissected calyx, external surface, with detail of indumentum; e. dissected corolla with androecium; f. anther; g. pistil; h. immature capsule (Goyder 8068, CAS, K, LUBA). — Scale bars: a = 3 cm; b–c = 1 cm; d–e, g–h = 5 mm; f = 2 mm. — Drawn by Juliet Williamson.

Fig. 2 Species of Justicia sect.Monechma from Angola.a–c. Justicia cubangensis I.Darbysh. & Goyder; d–e. Justicia moorei I.Darbysh. & Goyder; f. Justicia virgultorum (S.Moore) I.Darbysh. & Goyder (a–c. Goyder 8068; d–e. Goyder 8210; f. Goyder 8471). — Photos by D. Goyder.