Justicia eriniae I.Darbysh., 2019

Justicia eriniae I.Darbysh. View in CoL , sp. nov. — Fig. 3; Map 1 View Map 1

Similar to Justicia tricostata Vollesen but differs in the capsule being puberu- lous and having black seeds (vs capsule glabrous, seeds mottled grey and black in J. tricostata ); the bracts and bracteoles being shorter,the latter being 4.5–6 mm long, typically ± half the length of the calyx (vs 6.5–12.5 mm long and only slightly shorter than or subequal to the calyces); the inflorescence being lax throughout (vs typically dense throughout or at least distally); and the stem and inflorescence indumentum being ± patent (vs indumentum antrorse). In Angola, it is most likely to be confused with Justicia glaucifolia (S.Moore) I.Darbysh. & Goyder (see below) which shares the lax secund inflorescences with an eglandular indumentum, but J. eriniae differs in the leaves being lanceolate with a markedly acute apex and a length: width ratio 4.5–6.7: 1 (vs leaves obovate with a rounded or obtuse apex, length: width ratio 2.5–2.6: 1 in J. glaucifolia ); the stem,inflorescence rachis and calyces etc. having a spreading / patent indumentum (vs indumentum antrorse);and in having larger flowers, the calyx lobes 8–9 mm long, the corolla 18–18.5 mm long (vs calyx lobes ± 6 mm long, corolla ± 14 mm long). See Table 2. — Type: Tripp & Dexter 6917 (holo K; iso COLO [not seen], LUBA [not seen]), Angola, Namibe Prov., between Bibala and Assunçao, S14.79891 E13.22217, 189 m, fl. & fr., 10 Apr. 2017.

Etymology. The epithet ‘ eriniae ’ honours Dr. Erin Tripp of the Museum of

Natural History ( COLO Herbarium) at the University of Colorado, a leading authority on Acanthaceae , great all-round naturalist and collector of the type specimen of this species. Dr.Tripp also kindly provided extra floral measure- ments from the COLO isotype .

Brittle-stemmed herb, with many-branched stems to 50–75 cm tall; stems quadrangular or somewhat 6-angular, pale-pubes- cent throughout, hairs patent or those immediately above the nodes somewhat deflexed. Leaves with a short, ill-defined petiole to 4.5 mm long, blade lanceolate to narrowly so, longest blades 57–65 by 8.5–13 mm (length: width ratio 4.5–6.7: 1); base cuneate, margin entire, apex acute, surfaces sericeouspuberulous when young, more sparse at maturity when hairs most numerous along veins beneath, midrib above and margin; lateral veins 2 or 3 per side, markedly ascending, with scalariform tertiary venation between midrib and lateral veins. Inflorescences terminal and sometimes also in upper axils, secund spikes 5.5–8 cm long, each node of inflorescence single-flowered, lax, up to 9 nodes along spike; peduncle 10–19 mm long, rachis eglandular-puberulous; bracts paired, lanceolate, 3.5–5.5 by 1.5 mm in central portion of spike (those at lower- most fertile node can be longer and more linear), at first pale yel- lowish with 3 prominent (brown-)green veins, becoming brown with age; flowers sessile, calyx immediately subtended by erect paired bracteoles, resembling bracts but 4.5–6 by 1–2 mm, apex ± attenuate, 3-veined but midvein apparently composed of two partially fused parallel veins. Calyx divided almost to base into five subequal linear-lanceolate lobes 8–9 by 1.3–2 mm in flower, extending somewhat in fruit when up to 10.5 mm long, pale yellowish cream with three markedly raised parallel green veins, apices green, external surface eglandular-puberulous, hairs along the margins longer and somewhat crisped. Corolla 18–18.5 mm long, white, eglandular-pubescent externally; tube ± 10.5 mm long including unexpanded basal portion 2.5–3.5 mm long, floor of expanded throat markedly ventricose, 6.5 mm deep centrally (when flattened), 3 mm deep at mouth; upper lip hooded, ± 8 mm long, apex shallowly bilobed; lower lip ± 8.5 mm long, apex 3-lobed, lobes rounded, 2.5 mm long, median lobe broader, palate of lower lip with weakly raised ‘herring-bone’ pattern. Stamens inserted ± 7–8 mm from base of corolla tube; filaments 6–7.5 mm long; anthers with thecae overlapping for ± 1/3 their length, somewhat oblique, upper theca 1.2 mm long, lower theca 1.45–1.5 mm long, with basal pale yellowish appendage 1.7–1.9 mm long, apex unevenly and inconspicuously forked, anther connective pilose at apex. Ovary oblong-ovoid, ± 3 mm long, sparsely puberulous towards apex; style ± 16 mm long, sparsely puberulous, hairs becom- ing denser in proximal portion; stigma minutely bifid, one lobe much reduced. Capsule 2-seeded, 10.5–11 mm long, shortly stipitate, eglandular-puberulous externally; seeds lenticular, compressed, black, 3.5–4 mm diam, with smooth surface.

Distribution & Ecology — Justicia eriniae is recorded from Namibe Province of Southwest Angola where it is known only from the type specimen. It was recorded from roadside thorny scrub in lowland Colophospermum mopane woodland at 189 m elevation.

Conservation — Only a small population of fewer than 10 plants was recorded at the single locality known for this species, but the surrounding areas were not extensively searched by the collectors, and potentially suitable habitat is widespread in the region. Although it was collected from a roadside site, it was in a largely undisturbed area with very little traffic. Mining of marble occurs in the vicinity of the type locality but does not appear to impact this species (E.A. Tripp, pers. comm.). With more information needed on its full range and abundance, J. eriniae is currently considered to be Data Deficient ( DD) but it may prove to be of Least Concern as threats appear to be minimal .

Taxonomic notes — Justicia eriniae is most likely to be confused with J. tricostata , a recently described species from rock outcrops and stony soils in miombo woodland in Zambia and Tanzania ( Vollesen 2010, 2015) which does not extend to Angola. They share the combination of lanceolate leaves, eglandular inflorescence indumentum and prominently 3-veined calyx lobes, bracts and bracteoles. This latter character is widespread in the perennial species of Justicia sect. Monechma Group I sensu Kiel et al. (2017; see Discussion below) but is particularly marked in these two species. However, J. eriniae clearly differs in the characters listed in the diagnosis, and also occurs in much drier habitat.