Chamaedorea tacanensis Pérez-Farrera, Villar-Morales & Hodel, 2021

Pérez-Farrera, Miguelangel, Gutiérrez-Ortega, José Said, Hodel, Donald R., Villar-Morales, Diego, Santos-Hernández, Nancy Gabriela & Martínez-Camilo, Rubén, 2021, A new species of climbing Chamaedorea (Arecaceae) from Chiapas, Mexico, Phytotaxa 522 (2), pp. 94-108 : 101-103

Chamaedorea tacanensis Pérez-Farrera, Villar-Morales & Hodel sp. nov. ( Fig. 7 ).

TYPE: — MEXICO. Chiapas: Cacahoatán municipality, Ejido Agua Caliente, Tacaná Volcano , 1200 m a. s. l.., Martínez-Meléndez 3450 (holotype HEM; isotypes MEXU, CHIP, CAS).

Chamaedorea tacanensis is a climbing species that differs from C. elatior in the pinnate-leaved seedling and juveniles, the linear pinnae, the emerging pruinose petiole, the longer leaf rachis and blade, and the longer peduncle.

Solitary slender, climbing, understory palm 3.5–8 m tall or long. Stem 5.2–8.4 cm diameter. Leaves 6–14, pinnate when seedling and adult, spreading, arching; sheath to 60 cm long, elongate, tubular, green, persistent; petiole 13–70 cm long, flat and green adaxially, pale and rounded abaxially with a slightly prominent light green ridge extending onto sheath, emerging pruinose; rachis 163–251 cm long, sharply angled and green adaxially, rounded and with a very faint green band abaxially; blade 170–245 cm long in very robust individuals; pinnae 42–60 on each side of rachis, largest 26–48 cm long, 1.8–3 cm wide, straight, mostly linear but sometimes linear-lanceolate, alternate proximally, opposite distally, equally attenuate, strongly indurate-calloused at very narrowed base, not rigid, tips frequently drooping, progressively more reflexed, hook-like, and downward-pointing distally, deep green, a prominent central midrib and numerous but inconspicuous veins of lesser order on each side of this. Inflorescences interfoliar, breaking through old sheaths, spreading; peduncles 20–50 cm long, erect to ascending, green where exposed; bracts 5–7, prophyll and most proximal peduncular bract close set, prophyll 1.5–3 cm long, most distal peduncular bract 8–19 cm long, often concealing a small rudimentary bract and, on pistillate inflorescences, exceeding peduncle, bracts tubular, stout, brown at anthesis, longitudinally striate-nerved, acute-acuminate, bifid; staminate rachis 20–50 cm long; rachillae up to 50, these to 27 cm long, proximal ones largest, 2–3 mm diameter, simple, green, spreading; pistillate rachis 5–11 cm long; rachillae 10–20, 8– 22 cm long, proximal ones slightly larger, green in flower, black in mature fruit. Staminate flowers in moderately dense spirals, slightly sunken in superficial, elliptic depressions 1–2 mm long, 3.2–4 × 3–3.5 mm, globose, slightly depressed apically in the center, bright yellow, strongly aromatic; sepals 1–1.7 × 1.5–2 mm, connate basally to half their length, broadly deltate, nerveless; petals 3.5–4.3 × 2.2–2.5 mm, elliptic-obovate to obovate, yellow, slightly nerved adaxially, connate basally and adnate apically to pistillode and corolla opening by lateral slits at anthesis, becoming free apically with age; stamens 2.3–3.3 mm tall, the filaments equal or slightly shorter than the anthers; pistillode 2.2–2.7 mm high, slightly shorter or equal to stamens, columnar, distal half swollen, truncate apically, greenish. Pistillate flowers in moderate to remote spirals, slightly sunken in superficial elliptic depression 1–2 mm long, 2.5–3 × 2.4–2.8 mm, globose-ovoid, yellow; sepals 1.3–1.6 × 2–2.3 mm, free or briefly connate basally, broadly rounded apically; petals 2–3 × 2–3 mm, broadly lanceolate to ovate, imbricate in basal ¾, acute apically, yellow, fleshy, nerveless; staminodes absent; pistil 2.5 mm long, stigma lobes slightly recurved. Fruit 7–11 mm diameter, globose, black with a slight glaucous bloom; seeds 4–7 mm diameter, globose, brownish.

Additional specimens examined: — MEXICO. Chiapas. Municipality de Cacahoatán: Ejido Chiquihuite, approximately 1.5 km northwest from El Berral, M. Martínez Meléndez & M. Antonio Domínguez Vázquez 1672, 1819 ( HEM); Ejido Agua Caliente, approximately 1.8 km southeast in footpath from Agua Tibia, M. Martínez Meléndez & M. Carlos Robles Molina 2517 ( HEM); Ejido Agua Caliente, approximately 1.9 km southeast in a straight line on trail to Ejido Benito Juárez, El Plan, M. Martínez Meléndez & M. Carlos Robles Molina 2605 , 2618 ( HEM);

Ejido Agua Caliente, approximately 2 km southeast from town, M. Martínez Meléndez & M. Carlos Robles Molina 2652 ( HEM); Ejido Agua Caliente, Tacaná Volcano, M. Martínez-Meléndez 3456 ( HEM). Municipality of Unión Juárez, Ejido Chiquihuite, trail to the top of Tacaná Volcano, near Paso del Gato, at El Sisil, M. Martínez Meléndez & M. Dina Estrada Marroquín 1569 ; Ejido Chiquihuite, approximately 1.2 km southwest in the trail to Santa Teresa, R. Martinez Camilo 1433, 1470 ( HEM). GUATEMALA. San Marcos: kilometer 270 on road from Quetzaltenango to San Marcos, 1500 m, Hodel and Castillo-Mont 914 ( AGUAT, BH); San Marcos: Finca El Porvenir, lower slopes of Volcán Tajumulco, 1500 m, Steyermark 37101 ( F).

Habitat. The type locality of Chamaedorea tacanensis is “Volcán Tacaná” within the Tacaná Volcano Biosphere Reserve, which is mostly covered by tropical montane cloud forest. Granitic soils are frequently common in areas around Tacaná Volcano (Martínez-Camilo et al. 2019). Vegetation is similar where the Guatemalan population occurs although the substrate is a well-structured clay loam.

Chamaedorea tacanensis forms part of the understory of tropical montane cloud forest. This vegetation type occurs from about 1500 to 2600 m elevation. Several species of Quercus L., mainly Q. benthamii A.DC. , Q. skinneri Benth. , and Q. lancifolia Schltdl. & Cham. , which sometimes reach approximately 35 m in height, dominate the forest canopy. Other frequent species include Amphitecna montana L.O.Williams , Glossostipula concinna (Standl.) Lorence , Oreopanax xalapensis (Kunth) Decne. & Planch. , Dendropanax arboreus (L.) Decne. & Planch., and D. leptopodus (Donn.Sm.) A.C.Sm. ; species of the Lauraceae ( Ocotea Aubl. , Nectandra Rol. Ex Rottb. , Persea Mill. ), Melastomataceae ( Conostegia D.Don , Miconia Ruiz & Pav. and Meriania Sw. ), and Rubiaceae ( Arachnothryx Planch. , Psychotria L. and Rondeletia L.); species of the genera Symplocos Jacq. (Symplocaceae) and Saurauia Willd. (Actinidiaceae) . Considered one of the richest and most diverse vegetation types ( Toledo-Aceves et al. 2011, Martínez-Camilo et al. 2019), it still predominates in its elevational range in spite being severely restricted and modified by human activities.

Phenology. The species flowers from December to February and bears fruits from March to May.

Etymology. The specific epithet refers to the Tacaná Volcano Biosphere Reserve in Chiapas, the type locality of the species.

Figures

FIGURE 7. Chamaedorea tacanensis. (A–B) Plants in the wild. (C–E) Inflorescence. Photo C by Dimas H. De Coss Aguilar.