Ceroxylon ravenii Villalba & L. Valenz., 2021

Valdivia, María Isabel Villalba & Gamarra, Luis Valenzuela, 2021, A new species of Ceroxylon (Arecaceae) from Cordillera Azul National Park - Peru, Phytotaxa 483 (3), pp. 267-276 : 269-274

Ceroxylon ravenii Villalba & L. Valenz. , sp. nov. Type:— PERU. Region Loreto, Prov. Ucayali, Dist. Pampa Hermosa. Cordillera Azul National Park , low montane forest, clay-sandy soil, 06°56’09.04”S, 075°58’19.3”W, 1240 m, 23 October 2017. L. Valenzuela, J. Flores & G. Shareva 33565, staminate specimen, with flowers (holotype HOXA !, isotypes USM !, MO! ). Figs. 1–5 .

Diagnosis:—Acaulescent dioecious palm with 10–14 leaves, leaves 3–4 m long, forming a funnel-shaped crown, hastula-like projection 1.0– 3.1 cm long, one inflorescence born at a time, peduncle of pistillate inflorescence 50–60 cm long, peduncle of staminate inflorescence 33–42 cm long, fruit 2.3–2.4 cm in diameter, with smooth epicarp.

Acaulescent, dioecious palm. Leaves 10–14, 3– 4 m long, forming a funnel-shaped crown; leaf sheath and petiole 40–50 cm long, 4–5 cm wide at the base, completely covered with adpressed brown filiform scales on the abaxial surface, while the adaxial surface is covered with a thin layer of wax and scarce brown filiform scales; rachis 210–310 × 0.5–2 cm, adaxially flattened in about ½ of its length and ending in a well-defined 1.0– 3.1 cm long hastula-like projection, then keeled, covered with a thin layer of wax and translucent filiform scales, abaxially convex, covered with abundant adpressed brown filiform scales; pinnae 38–50 on each side, regularly arranged in one plane, adaxial surface covered with thin translucent wax layer, mid-rib covered with translucent filiform scales, abaxial surface covered with brown adpressed filiform scales; basal pinnae 30.0–45.2 × 0.6–1.3 cm, space between pinnae 2.3–2.8 cm; middle pinnae 54.0–70.0 × 2.5–3.5 cm, slightly pendulous, space between pinnae 2.7–3.5 cm; apical pinnae 51–52.5 cm × 0.4–0.7 cm, pendulous at the tips, united along the margins or spaced 1.5–2.3 cm. Staminate inflorescence 65.0– 70.0 cm long, born one at a time, peduncle 33–42 cm long, 0.8–1.0 cm wide at apex; prophyll 15.0 – 17.5 cm long; peduncular bracts 3, 17– 60 cm × 1.2–3.5 cm; rachis 32–38 cm long, with 36–44 first order branches, each subtended by a membranous, long acuminate bract 0.5–1.0 cm × 0.3–0.6 cm, each first order branch with 2–9 second order branches 2.5–7.0 cm long; prophyll and peduncular bracts covered by abundant filiform scales, rachis and branches glabrous. Pistillate inflorescence 75.0–80.0 cm long, born one at one time, peduncle 50–60 cm long, 0.8 cm wide at apex; prophyll 24–25 cm long; peduncular bracts 6, 24.0–65.0 × 2.5–3.5 cm, the distal one 13.0–14.0 cm in length, inserted at the apex of the peduncle; rachis 20.0–25.0 cm long, with 24–26 first order branches, each subtended by a triangular, long acuminate bract 0.6–2.5 × 0.3–0.6 cm long, each first order branch with 4–8 second order branches 2.0–5.0 cm long; prophyll and peduncular bracts covered by abundant filiform scales, rachis and branches glabrous.

Staminate flowers sepals 3, broadly-triangular, acuminate, 0.15–0.20 × 0.05–0.10 cm, connate basally for 0.2 mm; petals 3, triangular, long acuminate, 0.5–0.6 × 0.08–0.10 cm, connate basally for 0.6–1.0 mm; stamens 10–12, alternating 2–3 antipetalous and 1–2 antisepalous, filaments 0.17–0.20 × 0.11–0.12 cm, inserted at mid-height in the central portion of the anther, anthers 0.21–0.23 × 0.08–0.10 cm long, anther connective not projecting, anthers not exceeding petals; pistillode trifid, 0.1 cm long. Pistillate flowers sepals 3, broadly–triangular, acuminate, 0.17–0.20 × 0.11–0.12 cm, connate basally for 0.2 mm; petals 3, elliptical, long-acuminate, 0.5–0.6 × 0.10–0.11 cm, connate basally for 0.5–1.0 mm; staminodes 10–12, alternating 2 antipetalous and 1–2 antisepalous, antisepalous filaments 0.16 cm long, antipetalous filaments 0.08 cm long, abortive anthers 0.10–0.11 × 0.07–0.08 cm; pistil globose, 0.28–0.3 × 0.18–0.20 cm, stigmatic branches 3, 0.10–0.12 × 0.02 cm, with papillose internal surface. Infructescence 130–140 cm long; peduncle 100–104 cm long, doubling in length as fruit matures; apical portion of rachis bare, due to the weight and size of the fruits. Fruits globose, orange when ripe, 2.3–2.4 cm in diameter, smooth exocarp; lateral stigmatic remnant near the base; pedicel 0.07–0.08 cm long. Seed spherical and smooth, 1.6–2.0 cm in diameter; hilum basal; embryo lateral, 0.3–0.4 mm from the hilum, 2.0 mm wide at base and 1.0 mm wide at apex.

Comparison with similar species:— Despite the lack of an aerial stem, Ceroxylon ravenii clearly belongs to the genus Ceroxylon ( Ceroxyloideae , Ceroxyleae subtribe), sharing many characters with the genus such as dioecy, splitting leaf sheaths with margins generally fibrous, unisexual flowers, sepals and petals basally connate, basifixed stamens, barely dimorphic flowers, triovulate trilocular gynoecium and fruit with basal stigmatic remains ( Dransfield et al. 2008).

Ceroxylon ravenii is similar to C. quindiuense and C. parvifrons in the leaves, since the pinnae are regularly distributed along the rachis, and the fruits have a smooth epicarp. Likewise, we found that the location of C. ravenii overlaps with the elevation of range distribution of C. amazonicum and C. parvum . However, through the comparison of the species with the review carried out by Sanín & Galeano (2001), the following morphological differences were found:

Ceroxylon ravenii has an acaulescent habit, completely different from the other species of the genus, which have by contrast, tall stems. The hastula-like projection found roughly in the middle of the rachis, though characteristic in Ceroxylon , is notably bigger in C. ravenii than in other species in comparison ( Table 1 ). C. ravenii bears one pistillate inflorescence at a time, while the other species have more than one pistillate inflorescence at the same time.

Another contrasting feature is the length of peduncle of the pistillate inflorescence and rachis of the staminate inflorescence, which are smaller in C. ravenii than in the other species ( Table 1 ). Finally, the pinnae on the leaves are regularly inserted on each side in C. ravenii , while in C. parvum they are irregularly arranged in groups of 2, 3, 4; and inserted in 1–5 planes.

Etymology:— This species is named in honor of Dr. Peter H. Raven, director of the Missouri Botanical Garden from 1971 to 2011, who is one of the main promoters of botanical research in Peru and the world to preserve endangered plants, also considered a great defender of conservation and sustainable environment.

Ecology:— Ceroxylon ravenii is only known from the wilderness zone of Cordillera Azul National Park ( Fig. 1 ), located on one of the plateaus of a steep mountain of the “Agua Caliente” formation, whose elevation ranges from 500 to 1800 m. A population of approximately 40 adult individuals has been recorded in lower montane forest at 1240 m elevation, on a sandy-clay soil, with exposed sandstone rocks, associated with other herbs such Anthurium sp. (Araceae) , Besleria sp. (Gesneriaceae) , Cyperus sp. (Cyperaceae) , Ophioglossum sp. (Ophioglossaceae) , Salpinga spp. (Melastomataceae) , Trichomanes sp. (Hymenophyllaceae) , shrubs of Cestrum sp. , Solanum sp. (Solanaceae) , Rethyniphyllum fuchsioides (Rubiaceae) ; small trees like Cybianthus sp. (Primulaceae) , Lissocarpa sp. (Ebenaceae) , Drypetes sp. (Putranjivaceae) , Leonia sp. (Violaceae) , Strychnos sp. (Loganiaceae) and tall trees such as Chrysophyllum sp. (Sapotaceae) , Compsoneura capitellata (Myristicaceae) , Croton matourensis ( Euphorbiaceae ), Dacryodes sp. (Burseraceae) , Garcinia brasiliensis (Clusiaceae) , Guatteria sp. (Annonaceae) , Iryanthera sp. (Myristicaceae) , Ladenbergia sp. (Rubiaceae) , Leonia sp. (Violaceae) , Macbrideina peruviana (Rubiaceae) , Senefeldera inclinata (Euphorbiaceae) , Symphonia globulifera (Clusiaceae) , Sterigmapetalon sp. ( Rhizophoraceae ), Ternstroemia sp. (Pentaphylacaceae) and Virola spp. (Myristicaceae) among others.

The known population of adult individuals falls within approximately 1 hectare. At the moment, the species is apparently protected, since it is located within a protected natural area. However, the data are insufficient to determine the status of conservation. The staminate specimen collected in October 2017, as well as the pistillate specimens collected in September 2018, were found with reproductive structures only by coincidence; therefore it is not possible to establish the phenology of the species at this time.

Other specimens examined:— Region Loreto, Prov. Ucayali, Dist. Pampa Hermosa. Cordillera Azul National Park , low montane forest, clay-sandy soil, 06°56’07.5”S, 075°58’20”W, 1240 m, 15 September 2018. L. Valenzuela, J. Flores & W. Guerrero 35737B (pistillate specimen, flowers) ( HOXA!) ; L. Valenzuela, J. Flores & W. Guerrero 35737A (pistillate specimen, infructescence) ( HOXA!) .

Figures

FIGURE 1. Geographical distribution of Ceroxylon ravenii in Cordillera Azul National Park – Peru.

FIGURE 2. Habitat of Ceroxylon ravenii. A: Agua Caliente geological formation; B: Small plateau within the Cordillera Azul National Park (Peru), lower montane forest, clay-sandy soil, very close to mountains with sandstone soil; the waters that flow from this mountain are part of the Ushpayacu river, a tributary of the Cushabatay river; C: adult individual of C. ravenii in the understory (Images by L. Valenzuela).

FIGURE 3. Ceroxylon ravenii. A: Habit; B: Middle pinna tips; C: Basal pinna tips; D: Pistillate flower; E: Insertion of staminodes; F: Gynoecium; G: Infructescence; H: Fruit; I: Staminate flower; J: Insertion of stamens. (Drawings of pistillate parts from: L. Valenzuela 35737A, L. Valenzuela 35737B, staminate parts: L. Valenzuela 33565).

FIGURE 4. Ceroxylon ravenii. A: Habit; B: Leaf (tips of middle pinnae); C: Leaf, middle portion, showing the adaxial surface; D: Leaf, middle portion, showing abaxial surface; E: Leaf, basal portion; F: Leaf sheath and petiole, abaxial view; G: leaf sheath and petiole, adaxial view; H: Hastula-like projection; I: Apical pinnae, showing adaxial surface; J: Apical pinnae, showing abaxial surface. (Images: L. Valenzuela).

FIGURE 5. Ceroxylon ravenii.A: Inflorescence branches with old staminate flowers; B: Pistillate inflorescence at bud stage; C: Pistillate inflorescence showing flowers in bud; D: Staminate inflorescence; E: Staminate flower; F: Pistillate flowers at bus stage; G: Infructescence; H: Fruit; I: Seed; J: Embryo. (Images: L. Valenzuela).