Aphelandra almanegra P. Gallego, J.R.I. Wood & J.C. Franco

Gallego, Pablo C. & Wood, John R. I., 2024, Aphelandra almanegra (Acanthaceae), a new species from the dry forests of the Cauca River canyon in Antioquia department, Colombia, Phytotaxa 652 (3), pp. 208-216 : 209-215

Aphelandra almanegra P. Gallego, J.R.I. Wood & J.C. Franco sp. nov. ( Figs. 1 & 2 )

Type: — COLOMBIA. Antioquia. Mun. Liborina: Vereda Chachafruto , Quebrada Canelón Blanco Alta , Predio Palo Hueco , 819 m, 6°42’8.19”N, 75°49’6.75”W, 1 March 2021 (fl & fr), P. Gallego et al. 1284 (holotype: HUA-229338 !)

Diagnosis: — Aphelandra almanegra differs morphologically from Aphelandra pulcherrima by its stout, profusely branched habit, capable of reaching up to 5 meters in height (vs. slender, sparingly branched habit up to 3 meters high), the strigose indumentum of apical branches (vs. pubescent to tomentose), its leaf dimensions 6.0–34.4 × 3.2–14.7 cm (vs. 8–20 × 3.5–10 cm), leaf with abaxially appressed, sparsely strigose indumentum (vs. densely pubescent with spreading hairs), inflorescence comparatively longer, reaching up to 14.5(32) cm (vs. 10(20) cm long), the bracts notably long and wide: 7.3–12.4 × 4.2–7.8 mm with sericeous indumentum and ciliate margin (vs. 6.0–7.0 × 2.0–3.0 mm with puberulous indumentum and margin finely pubescent), ocelli 1 to 9 (vs. 1– 2) and corolla bright pink (vs. red).

Deciduous shrub up to 5 m high, profusely branched, main stem eventually stout (up to 12 cm dbh), apical branches terete to subquadrangular, ridged when dry, 3–6 mm diam., sparsely to densely strigose towards the apex, the trichomes pale brown, lenticels conspicuous, circular to elliptic, corky, internodes up to 7.5 cm long. Leaves isophyllous, 6.0–34.4 × 3.2–14.7 cm, elliptic, apex acuminate, base attenuate and strongly decurrent, margin undulate to shallowly crenate, chartaceous, adaxially glabrous, occasionally with scattered trichomes on the main veins, the costa flat or slightly impressed, lateral veins slightly raised, abaxially sparsely strigose, main veins eventually pubescent with axils pilose, lateral veins 12–18 pairs, eucaptodromous, tertiary veins sinuous, petioles 0.1–2.2 cm long., semiterete to slightly caniculate, sparsely to densely strigose; leaves subtending the inflorescence reduced, subsessile, ovate, basally cuneate to rounded, densely pilose, glabrescent, caducous. Inflorescence terminal, solitary or in fascicles of 1–3(5) spikes, sometimes also with spikes from the uppermost leaf axils; spikes up to 110-flowered, 4.8–14.5(32) cm long., 5–10 mm in diam., shortly pedunculate, rachis slightly angular, white-cottony-tomentose, trichomes lustrous; bracts greenish becoming orange-red apically, drying reddish brown, imbricate, 7.3–12.4 mm long, 4.2–7.8 mm wide at midpoint, rhombic–ovate, acute to shortly acuminate, ciliolate, abaxially sparsely to densely sericeous, adaxially glabrous with sparsely sericeous apex, ocelli 1–9, irregularly orbicular, elliptic or oblong, contiguous or separate, ocellar area 0.5–3.3 × 0.4–1.7 mm, dark brown when dry; bracteoles 4.4–5.4 × 1.7–2.3 mm, broadly lanceolate, cymbiform, dorsally keeled, sparsely to densely silky on the keel, ciliolate, hyaline-margined; calyx 8–10 mm long., apically puberulous, posterior segments 8 × 2–3 mm, broadly lanceolate, shortly acuminate, lateral segments 7.3–8.3 × 1.6–2.3 mm, lanceolate, anterior segments 7.8–9.0 × 2.0– 2.8 mm, broadly lanceolate, segment margin ciliate, hyaline, indument sparsely sericeous. Flowers bright pink, 4.0– 5.2 cm long., tube 1.8–2.8 cm long, 0.2–0.4 cm wide at base, exterior puberulous, interior glabrous except for pilose base, papillate, upper lip 13–21 × 4–6 mm long., 2-lobed, lobes 5–8 × 1–3.7 mm, broadly lanceolate, attenuate, lower lip 3-lobed, lobes subequal, middle lobe 18–25 × 5–6 mm, oblong to oblong-elliptic, acute, becoming strongly reflexed and recurved, free portion of lateral lobes 0.3–0.6 × 0.2–0.5 mm, deltoid, obtuse; stamens 4, included in the upper lip, 3.2–4.6 cm long., exserted about 20 mm beyond corolla mouth, glabrous, connective and base pilose; anthers cream, 5–6 mm long.; ovary 3–4 mm long., subpyriform, glabrous; style 3.8–4.2 cm long., exceeding anthers, filiform, glabrous with short, stout trichomes on the base; stigma bilobed. Capsule 1.3–2.0 × 0.4–0.7 cm, oblong-elliptic to obovoid, glabrous, surface foveate, brown; seeds 3.8–4.7 × 3.2–3.7 mm, suborbicular, muricate, brown.

Distribution and habitat: — Aphelandra almanegra is endemic to dry forests of the Cauca river canyon in the department of Antioquia, between the municipalities of Santa Fe de Antioquia and Ituango. It is found on rocky ground, frequently in the beds of ephemeral streams on steep slopes at elevations between 266–1100 m. ( Figs. 3 & 4 )

Phenology: —Flowering in November–March, and fruiting March–April.

Preliminary conservation status: — Aphelandra almanegra is exclusively distributed in the dry forests of the upper Cauca river basin. García et al. (2014) describe the ecosystem in this region as critically degraded, with less than 20% of the original cover remaining. The forest consists of often isolated patches on riparian slopes, that are fragmented and with poor connectivity due mainly to human activities such as overgrazing, infrastructure, fire, and mining ( Miles et al. 2006). Despite the above, A. almanegra is relatively abundant locally, and has four sub-populations with an Area of Occurrence (AOO) of 52 km ² in an Extent of Occurrence (EOO) of 576 km ². It should be categorized as Vulnerable (VU) according to the criteria B: B1a+B2a considering the current state of its habitat and the absence of official protected areas in its distribution area.

Etymology: —The epithet “almanegra ” refers to the vernacular name given to this plant by the people living in the species’ area of distribution. It means “black soul” and alludes to its black heartwood. ( Fig. 2E )

Additional specimens examined (paratypes): — COLOMBIA. Antioquia. Mun. Briceño: Cañon del Río Cauca, Central Hidroeléctrica de Ituango , Chirí , 581 m, 07°5’31.15’’N, 75°39’56.17’’W, 16 November 2022, A. Rivera et al. 370 (JAUM-094019) ; Vereda la Calera, Quebrada Tablones, Sector Ticuitá , 266 m, 7°8’16.69”N, 75°38’50.25”W, 17 January 2022, A. Idarraga et al. 8441 (JUAM-094000). Mun. Ituango : Hda. San Juan de Rodas , [1000–1100 m, 7°8’17.40”N, 75°40’56.44”W], 13 December 1980, D. Sánchez 252 (MEDEL-25020) ; Villa Cauca, depósito de la vía industrial, 350–650 m, 05°59’34.77’’N, 74°34’1.22’’W, 11 February 2010, P. Trujillo & H. Salazar 4815 (HUA-186881). Mun. Liborina: Cañón del río Cauca, Central Hidroeléctrica de Ituango , Sector Sucia, 462 m, 06°41’9.71’’N, 75°49’59.36’’W, 15 December 2022, A. Rivera et al. 378 ( JAUM) ; El Cauco, 702 m, 6°44’55.16”N, 75°50’21.94”W, 28 November 2014, A. Caro et al. 64 (MEDEL-64152) ; Km 4 of road Liborina-Sabanalarga (32 Km before Sabanalarga), 920 m, 06°42’’ N, 75°49’’ W, 8 November 1988, J. L. Zarucchi et al. 7253 (COL-363012, HUA-59508, MEXU-966277 [digital image], US-3148983 [digital image]). Mun. Olaya : Carretera que conduce al corregimiento de Llanadas, 800– 1000 m, 6°40’59.99”N, 75°49’0”W, 22 December 2002, J. C. Madrugo et al. 887 (COL-514073, MEDEL-44752). Mun. Sabanalarga: Camino del pueblo hacia los llanos de Niquía, 617 m, 07°5’31.15’’N, 75°39’56.17’’W, 15 March 2018, J. Jiménez & L. Zapata 2030 (HUA-220066) ; Cañón del río Cauca, Central Hidroeléctrica de Ituango, Bocas de Niquía , 526 m, 06°51’47’’N, 75°50’00’’W, 15 December 2022, A. Rivera et al. 377 ( JAUM). Mun. Santa Fe de Antioquia: Vereda El Espinal , Quebrada la Carvajala, 630 m, 6°31’N, 75°51’W, 22 November 2015, D. A. ZapataC. 1524 (JAUM-70049, JAUM-72148) ; Sector Filadelfia, vía que conduce a Cañas Gordas , a borde de carretera, 697 m, 06°34’15.74’’N, 75°50’23.03’’W, 18 January 2022, D. A. Zapata-C. 2677 (JAUM-093637, UDBC barcode- 047319 [digital image]) ; Carretera antigua Santa Fe de Antioquia-Manglar, 4 Km orilla de carretera, 500 m, 06°35’N, 75°55’W, 12 April 2022, F. J. Roldan 3245 (HUA-120632) .

Notes: —The new species resembles Aphelandra pulcherrima , A. barkleyi Leonard (1953: 221) and A. mildbraediana Leonard (1953: 218) , species 100–102 in the monograph by Wasshausen (1975). The differences between these species and A. almanegra are set out in Table 1 and Fig. 5 .

Aphelandra almanegra could also be compared with Aphelandra glabrata Willd. ex Nees (1847: 296) and Aphelandra tetragona (Vahl 1795:5) Nees (1847: 295) , the former not recognized as distinct by Wasshausen (1975) but reinstated by McDade (1988). From A. glabrata , a widely distributed species from Colombia to Bolivia ( McDade, 1988), it differs by its strigose (vs. pubescent) stems, larger leaves 6.0–34.4 × 3.2–14.7 cm (vs. (7)10–23 × (3) 4–8 cm), tertiary venation sparsely and inconspicuously sinuous (vs. prominently sinuous), floral bracts larger 7.3–12.4 × 4.2–7.8 mm (vs. 4.5–7 × 4–5 mm), abaxially sparsely to densely sericeous (vs. glabrous or minutely puberulous), extrafloral bract nectary composed of solitary to several large glands (vs. composed by numerous minute glands), stigma bilobed (vs. oblique), and corolla bright pink (vs. red to orange). From A. tetragona , a native of Venezuela, it differs by its relatively small and sparsely strigose leaves (vs. larger and strictly glabrous leaves ( Nees von Esenbeck 1847:295; Leonard 1954: 362)), strongly decurrent leaf base (vs. shortly decurrent ( Llamozas 2016: 51)), petioles reaching up to 2.2 cm long (vs. petioles up to 17 cm long ( Wasshausen 1975: 99)), leaves subtending the inflorescence notably reduced and densely pilose (vs. slightly reduced, “foliaceous” ( Vahl 1794:5), apparently glabrescent (Lockhart, 130 (K)), shorter corollas up to 5.2 cm (vs. up to 7.0 cm ( Wasshausen 1975: 99)). The corolla color in A. tetragona has been reported as bright pink to red by Wasshausen (1975: 99), but all specimens we have been able to review have red corollas. ( Table 1 ).

Aphelandra almanegra is closely related to A. daemonia Leonard (1953: 223) and A. incerta Leonard (1954: 362) , which were treated as distinct species by Leonard (1953) but were included in A. pulcherrima by Wasshausen (1975: 88). A. pulcherrima as currently delimited, could correspond to a supraspecific assemblage with associated nomenclatural problems as suggested by McDade (1988). Attributes of the floral bracts should serve to distinguish A. almanegra from any of these entities.

Figures

FIGURE 1. Aphelandra almanegra. A. Flowering branch with axillary and terminal inflorescences B. Floral bract showing indumentum and contiguous glandular ocelli C. Bracteoles D. Calyx; from left to right: posterior lobe, pairs of lateral and anterior lobes E. Lateral view of flower with its lower lobe extended F. Interior view of flower. Note the hirtellous base of the filaments G. Stamen. H. Gynoecium. Note bilobed stigma and the base of the style with short, stout trichomes I. Dehiscing capsule J. Seed. (Illustration by Marcela Morales).

FIGURE 2. Aphelandra almanegra. A. Flowering branch B. Terminal inflorescences showing spikes with fruits and flowers C. Terminal inflorescence with multiple spikes D. Close-up view of a flower spike, showing the position of the corolla lobes E. Cross section of an apical branch showing black heartwood F. Much-branched shrubby habit. (Photos of fresh specimens of P. Gallego et al. 1284-HUA).

FIGURE 3. Geographical distribution of Aphelandra almanegra based on herbarium specimen data. Map prepared using QGIS v.3.28.2 (QGIS Development Team, 2023).

FIGURE 4. Dry forests in the upper part of the Cauca River Canyon, Department of Antioquia, Municipality of Liborina, Vereda Chachafruto. Location where Aphelandra almanegra thrives, mainly in small riparian forest remnants.

FIGURE 5. Illustration of informative characters between related species of Aphelandra. A–D. A. almanegra: A. Strigose apical stem indumentum B. Abaxial leaf surface sparsely strigose C. Subsessile inflorescence with multiple reduced leaves D. Bract length and sericeous bract indumentum E–H. A. barkleyi: E. Sparsely strigose, almost glabrous apical stem indumentum F. Abaxial leaf surface glabrous G. Notably pedunculate inflorescences H. Bract length and minutely and inconspicuously pubescent bract indumentum I–L. A. pulcherrima: I. Pubescent to tomentose apical stem indumentum J. Abaxial leaf surface pubescent K. Subsessile inflorescence L. Bract length and puberulous bract indumentum M–P. A. mildbraediana: M. Stem apical indumentum densely strigose N. Abaxial leaf surface indumentum minute and sparsely strigose O. Subsessile inflorescence P. Bract length and sparingly pubescent bract indumentum Q–T. A. glabrata: Q. Apical stem indumentum moderately pubescent R. Abaxial leaf surface pubescent S. Sessile inflorescence T. Bract length and minutely puberulous bract indumentum. (A, B, C from Zarucchi, 7253; D from J. C. Madrugo et al. 887; E, G from L. Uribe-Uribe 1319; F, H from W.R. Philipson 1351; I, L from J. Cuatrecasas 25517; J from O. Haught 3759; K from A. Dugand 2800; M from J. G. Hawkes 587; N, O, P from J. H. Torres & P. Pinto 2955; Q-T from C. Saravia 4668. All specimens from COL. In the bract images, the vertical bars correspond to 1 cm. Composed by Samir Gallego).