Aiphanes suaita R. Bernal, Sanín & Castaño, 2019

Bernal, Rodrigo, Castaño, Felipe & Sanín, María José, 2019, A new, overlooked species of Aiphanes (Arecaceae) from Santander, Colombia, Phytotaxa 405 (2), pp. 101-105 : 102-105

Aiphanes suaita R. Bernal, Sanín & Castaño , sp. nov.

Type:— COLOMBIA. Santander, Municipio de Suaita , corregimiento de San José de Suaita, La Meseta , quebrada La Lajita, 1694 m elev., 6.177275 ° N, 73.43047 ° W, 4 March 2018, Castaño et al. 1849 (holotype UIS; isotype FMB) .

Diagnosis:— Aiphanes suaita resembles Aiphanes simplex in its small size, short, cuneate pinnae, and spicate inflorescence. However, it differs from that species in its solitary stem, 3 cm diam. (vs. stems densely cespitose, up to 20 per plant, 1 − 2 cm diam.), the dark brown spines on the leaf sheath and the petiole (vs. yellowish spines), and the arrangement of the staminate flowers on the inflorescence axis.

Stem solitary, 1 − 2 m tall, 3 cm diam., armed with black spines to 6 cm long. Leaves 8; sheath 22 cm long, with a dark brown indumentum, densely covered with flattened dark brown spines 2 − 4 cm long; petiole 22 cm, canaliculate above, armed with dark brown spines to 6 cm long, sparcely covered with a brown indumentum and short spines to 1 mm long; rachis 80 cm, with indumentum and armature like the petiole; pinnae 12 − 13 per side, in groups of 2 (− 5) separated by gaps 13 − 17 cm long, arranged in several planes, cuneate to broadly cuneate, 1.5 − 5 times as long as wide, praemorse at apex, truncate to deeply incised, with an up to 5 cm long finger-like projection on the distal margin, strongly plicate along secondary veins, dark green adaxially, abaxially light green and covered with scattered setae ca. 0.5 mm long, and a floccose, white indumentum, with up to 4 cm long black spines on the midrib; basal pinnae 8 − 14 x 3.5 − 6.5 cm; middle pinnae 12 − 20 x 5 − 7 cm; apical pinnae 1 − 2 ribbed, 9 − 15 x 3.5 − 5.5 cm, as broad as the remaining pinnae. Inflorescence erect, projected beyond leaves, spicate; prophyll green, 16 − 25 x 1.5 − 2.5 cm, sparsely covered with brown spines up to 3 − 4 mm long; peduncular bract light brown, 68 − 110 cm long, 1 − 1.5 cm wide, armed toward base with scattered spines ca. 5 − 6 mm long; peduncle 37 − 97 cm long, 3 − 5 mm diam. at junction with spike, striate, armed with 0.5–5 mm long brown spines, which are shorter and denser distally; spike 24 − 37 cm long, 4–6 mm diam., with brown spinules; flower triads in the proximal ½, the rest with staminate flowers arranged in dyads; triads slightly sunken into the rachis, each subtended by a 1 mm long bract with entire margins, which does not cover the pistillate flower before anthesis; dyads superficial, each subtended by a similar, smaller bract. Staminate flowers white, wider than long, 3 mm long, 4 mm wide, their axis perpendicular to that of the spike, apically compressed in bud; sepals free, imbricate, membranaceous, orbicular, cucullate, keeled, 2 mm long, 1–1.5 mm wide; petals connate for ca. 1/3 their length and adnate to the filaments towards the base, valvate, thick, ovoid, obtuse, 2.5 mm long, 2 mm wide; filaments white, subulate, fleshy, 2.5 mm long; anthers slightly broader than long, dorsifixed, 0.5 mm wide; pistillode trifid. Pistillate flowers 4 mm long, sunken for ½ their length; sepals free, broadly ovoid, membranaceous, strongly concave, lacerate, enclosing petals for 3/5, 2–3 mm long, 3–4 mm wide; petals connate for 2/3 their length, 5 mm long, the free portion reflexed, obtuse; staminodial cup 3 mm high, fleshy, remotely dentate, basally adnate to the petals; pistil ovoid, 4 mm long, 3 mm wide, glabrous, with three apical lobes. Fruits globose, purple to red when ripe, 6–8 mm diam. ( Figs. 1–2 ).

Distribution and habitat:—Endemic to the western side of the Eastern Cordillera of Colombia, where only two reduced populations, 56 km apart, have been located so far, both in the department of Santander, in well preserved primary to secondary, wet premontane forests, frequently associated to water streams, between 1600 and 1800 m.

Conservation status:—Only two isolated populations of A. suaita have been documented, with few individuals. The first population, composed of about 50 individuals, is located in a small forested area of ca. 6 km 2 near the village of San José de Suaita. Although the area is managed as a reserve by a private NGO, it is one of the last premontane forests still remaining in this region, and is under continuous pressure from local people. Moreover, the area of the reserve is currently for sale. Thus, its future is uncertain. The second population, located near El Carmen de Chucurí, about 56 km north of the latter, is found on the western slopes of the Serranía de Los Yariguíes, a mountain massif derived from the Eastern Cordillera. Most of the massif is within the Serranía de Los Yariguíes National Park, which preserves about 600 km 2 of premontane to montane wet forests and paramo. The five individuals found were growing just outside the national park, in a private area of primary forest. Although a stable population is probably found inside the park, no individuals were recorded during a two-week exploration of the area. The remnant forests adjacent to the national park are the focus of human activities such as colonization for agriculture and the establishment of pastures for cattle. The two known locations define a narrow triangle with base 56 km long and height 2.8 km, for an extent of occurrence (EOO) of 77.6 km 2 and an AOO of 16 km 2. Under this scenario, and considering the extremely narrow polygon of the EOO, we used the AOO as the defining criterion. Aiphanes suaita should then be considered as Endangered (EN), based on the IUCN (2012) categories, following the criteria B2ab (ii): area of occupancy (AOO) estimated to be less than 500 km 2 (B2), severely fragmented habitat (a), continuous decline of the area of occupancy [b(ii)].

Etymology:—The epithet suaita is a noun used in apposition. It is the name of the municipality where the new species was first located, the same name that the aboriginal village of the Guane Indians had at the time of the Spanish invasion (Pita Pico 2013).

Additional specimens:— COLOMBIA. Santander, Municipio de Suaita , corregimiento de San José de Suaita, La Meseta, 1700 –1900 m elev., ca. 6 ° 10’N, 73 ° 27’W, 30 July 2001, Galeano et al. 6883 ( COL) ; ibid., 1678 m elev., 6.17516º N, 73.42614º W, 7 August 2012, Bernal et al. 4815 ( COL) ; ibid., 1667 m elev., April 2018, Castaño et al. 2137 ( UIS). Municipio de El Carmen de Chucurí, Vereda la Bodega , 1789 m elev., 6.67956 ° N, 73.46122 ° W, February 2018, Castaño et al. 2050 ( UIS) .

Discussion:—The arrangement of the staminate flowers on the inflorescence axis was already noted by Galeano & Bernal (2002) as a character separating the plants from Santander from typical A. simplex . In A. suaita the flower axis is perpendicular to the inflorescence axis, so that the flowers are compressed along their longitudinal axis in bud, and appear triangular, whereas in A. simplex the staminate flowers in each triad are appressed to the rachilla axis, so that in bud they are laterally compressed and appear elongate. Additionally, in A. suaita the bracts subtending the flower triads are short, with smooth margins, and they do not cover the pistillate bud. In A. simplex the subtending bracts are large, with spinulose margins, and they cover the pistillate bud almost completely.

A molecular phylogenetic study of the genus Aiphanes (Sanín et al., unpublished) recovers A. suaita as sister to A. leiostachys , a species restricted to a small area in the northern end of the Central Cordillera, ca. 170 km west across the deep Magdalena River valley. Both species have pinnae that are strongly plicate along the secondary veins, and an incised, V-shaped pinna apex. However, A. leiostachys has inflorescences with numerous rachillae that are glabrous, in contrast with the spicate, densely spinulose inflorescence of A. suaita .

When Galeano & Bernal (2002) treated the specimens from Santander as A. simplex , they also discussed specimens from the department of Caquetá, ca. 550 km southwest of Suaita, along the Eastern Cordillera. These specimens have not been sequenced to date and their actual affinity is unknown. Morphologically, they appear to be more closely related to A. simplex than to A. suaita , because of their slender, cespitose stems and the yellowish spines on the leaf sheath. The biogeographical meaning of related microendemics occurring on the northern tips of the Central and Eastern Cordilleras is a topic that should be further explored.

The etymology of the generic name Aiphanes alludes to conspicuity (ai =always, phanes = evident). However, these understory palms are usually inconspicuous in the forest, and their identity is often cryptic. The recent taxonomic novelties in the genus highlight the need for a closer and deeper look at morphology, and stress the importance of its reciprocal illumination with molecular phylogenetics for discovering overlooked differences between species.

Figures

FIGURE 1. Aiphanes suaita.A.Habit (Castaño et al.2050), El Carmen de Chucurí, Santander, Colombia. B. Leaf apex and infructescence. C. Detail of pinnae (Bernal et al. 4815), San José de Suaita, Santander, Colombia.

FIGURE 2. Aiphanes suaita. A. Detail of spike, with staminate flowers at anthesis. B. Immature fruits (Bernal et al. 4815). San José de Suaita, Santander, Colombia.