Phragmotheca centinelensis J. C. Cerón, A. Fernández & J. E. Guevara, 2025

Guevara-Andino, Juan Ernesto, White, Dawson M., Pitman, Nigel C. A., Cerón, Juan-Carlos, Fernández, Andrea, Navas-Muñoz, Daniel & Alverson, William S., 2025, Phragmotheca centinelensis (Malvaceae, Malvoideae or Matisioideae), a newly-discovered, critically-endangered canopy tree species from a cloud forest in Pacific Ecuador, PhytoKeys 254, pp. 41-59 : 41-59

Phragmotheca centinelensis J. C. Cerón, A. Fernández & J. E. Guevara sp. nov.

Figs 1 , 2 , 3 , 4 , 5

Diagnosis.

The new species is morphologically similar to Phragmotheca hydra Fern. Alonso , but differs by its orbicular to oblong-elliptic (vs. orbicular-cordate) leaves with a mixture of long-branched fasciculate hairs and lepidote-stellate scales in the axils of the mid-vein and secondary veins on the abaxial leaf surface (vs. fasciculate hairs only); larger flowers (3.5–5.0 [including the pedicel] × 2.9–3.5 vs. 2.8–2.9 × 2.8–3.0 cm) with glabrous, concave-spoon-like (vs. linear spathulate) petals; longer, glabrous staminal column (2.9–3.6 vs. 1.7 cm and densely covered by stellate hairs); staminal lobes each bearing 6 thecae (vs. 3–4 thecae); glabrous (vs. sparsely covered with long-branched, fasciculate hairs) style; subcapitate (vs. subacute) stigma; narrower, patelliform fruiting calyx (3.3–3.9 vs. 4–4.5 cm in diameter); and ovoid (vs. globose) fruits that are proportionately more slender (5.0–7.0 × 4.0–5.3 vs. 5.2 × 6.0– 6.2 cm in diameter).

The semi-cordate leaf bases of this new species resemble those of Phragmotheca lemniscata Fern. Alonso , but P. centinelensis differs by its larger size (canopy trees to 35 m vs. small treelets); indument of abaxial leaf surfaces (sparse fasciculate hairs, lepidote-stellate scales and stellate-fasciculate hairs vs. dense lepidote scales); floral calyces (narrowly campanulate vs. tubular-fusiform); petals (orange or pink, glabrous, glossy, distally concave, non-reflexed, with slightly convolute margins vs. white-cream, linear-spathulate, distally reflexed, internally covered by a mixture of stellate and lepidote scales); shorter staminal column (2.9–3.6 vs. 7.0– 7.2 cm long, including the apical lobes) with apical lobes differing in indument (densely covered by septate simple hairs vs. glabrous); fruiting calyces (patelliform and covered by lenticels vs. discoid sub-cupular); and fruits (broadly ovoid vs. globose).

Type.

Ecuador – Santo Domingo de los Tsáchilas • (fl, fr, J. C. Cerón, A. Fernández, D. Navas, & L. Narváez 4643 (holotype: QCNE!, isotypes: F!, MO!, QCA!, WIS! )); Parroquia El Esfuerzo, Recinto Milton Murillo, Finca del Sr. Marlon Sarango , fragmento de bosque intervenido rodeado de pastizales; 0°35'54.53"S, 79°13'27.23"W; alt. 824 m; 01 Nov 2023 .

Description.

Canopy trees to 25–35 m tall; trunk cylindrical, longitudinally fissured and forming thin plates, buttressed to 7 m height (Fig. 2 A ), outer bark reddish with dispersed, irregular grey spots (Fig. 2 B ), internal bark fibrous (outer half reddish-brown, inner half yellow-cream; Fig. 2 C ); branches: main branches off trunk verticillate, smaller branches glabrous, terete, longitudinally fissured, with granular lenticels. Stipules 2–3 mm long, broadly triangular, caducous. Leaves alternate, clustered at the tips of the branchlets; petioles 3.6–12.2 cm long, 1–3.5 mm in diameter, terete, finely striate, densely pubescent, pulvinate at both ends. Leaf blades (Fig. 3 A, B ) glaucous when young, pale green abaxially when mature, coriaceous, entire, orbicular to oblong-elliptic, (6 –) 6.7–31.1 (32) × (5 –) 7.6–29.3 (– 30) cm, semi-cordate to deeply cordate at base with slightly asymmetric lobes 0.5–4.3 cm depth, the apex obtuse to shortly apiculate; the abaxial surface densely covered by a mixture of lepidote-stellate scales, stellate-fasciculate trichome and fasciculate trichomes; venation conspicuous on the abaxial surface; primary veins palmate near leaf base (Fig. 3 D ) with 5 basal nerves, 3–4 submarginal nerves slightly ascending to the leaf margin and with 5 pairs of secondary veins arising from mid-rib in distal 2 / 3 of blade, these with barbate tufts of fasciculate trichomes and sessile lepidote-stellate scales in their axils (Fig. 3 G ); tertiary venation also prominent on the abaxial surface (Fig. 3 E ), forming a conspicuous reticulum (inconspicuous on the adaxial surface), with golden lepidote-stellate scales on the lamina between nerves (Fig. 3 F ). Flowers slightly zygomorphic, solitary (Fig. 4 A, B ), borne opposite to leaves on short branches (brachyblasts), 3.3–5.2 cm long (including the pedicels), the pedicels 1.2–1.4 cm long, 0.3–0.4 cm in diameter, finely striate, covered with sessile stellate-lepidote scales and fasciculate hairs; floral bracts absent below the calyx. Calyx narrowly campanulate (Fig. 4 C ), 2.3–3.3 × 0.9–1.2 cm, densely covered by a brownish, floccose indument (imparting a granular appearance), broadly acuminate and 4 - lobed at summit, internally covered with adpressed sericeous hairs. Petals spathulate, distinctly bilobed at apex, strongly concave distally (Fig. 4 B, D ), the apex obtuse or rounded, the margins slightly convolute, 3.5–4.1 × 1.5–2.0 cm, orange or pink, glabrous, glossy, 2–4 inner corolla lobes covering the staminal tube and non-reflexed corolla tube lobes. Staminal column 2.9–3.6 cm long, the tube (16.5 –) 16.8–20.6 (– 21.0) × 0.4–0.6 mm long, orange, with 5 linear terminal lobes (Fig. 4 G ), each lobe 12.9–15.8 × 2.5–2.8 mm, orange or pink and bearing 6 thecae in two parallel lines on the adaxial surface, these surrounded by long, unbranched, septate hairs (Fig. 4 G – I ), with 14–16 foveae per theca. Ovary elongate, 1.5–1.7 mm long, 5 - carpellate, glabrous, the style not exceeding staminal filaments in length, longitudinally 6 - sulcate, the stigma capitate, spongy, glandular. Fruiting pedicel short, terete, 7.3–8.9 × 5.8–6.1 mm. Fruiting calyx patelliform and slightly dentate (Fig. 5 A, B ), surrounding only the basal 1 / 5 of the fruit and beset with cream-coloured lenticels. Fruit ovoid to broadly ovoid, 5.9–7 × 4–5.3 cm, the exocarp pale, smooth, finely fissured longitudinally (Fig. 5 C ) cream-coloured, sparsely granular with short, fasciculate hairs; the mesocarp fibrous-pulpy, white or cream-coloured and exuding yellowish mucilage (Fig. 5 D, E ), the endocarp densely fibrous, forming a woody pyrene with each of the five seeds (Fig. 5 F ). Mature seeds elliptic, 4–4.8 × 1.7–2 cm.

Phenology.

Flowering from November to December; fruiting between February and March.

Distribution.

Phragmotheca centinelensis is a large tree of non-flooded habitats in the Chocó cloud forests of Ecuador occupying a narrow altitudinal band between 600 and 1000 m elevation. It occupies mostly highly dissected terrain in the ridges of the Centinela area (Figs 6 , 7 ). According to our tree species inventory, P. centinelensis appears to be relatively rare in the region and possibly endemic to the Ecuadorian Chocó; the only two known populations are in cloud forest remnants in the western Andean foothills of Centinela. Although we know of no record of P. centinelensis from Colombia, it may occur in similar habitats of the adjacent Chocó Department. Despite its rarity, distinctive features make it conspicuous in the field, notably the large buttresses up to 7 m height, its reddish outer bark and the longitudinal fissures on the trunk.

Habitat and ecology.

Some of the most conspicuous floristic elements of the Centinela cloud forests include the families Fabaceae , Lecythidaceae and Malvaceae with dominant tree species including Ocotea insularis (Meisn.) Mez , Ruagea glabra Triana & Planch. , Guatteria sp. , Aegiphila alba Moldenke , Trichilia surinamensis (Miq.) C. DC. , Socratea exorrhiza (Mart.) H. Wendl. and Iriartea deltoidea Ruiz & Pav. The genera Eschweilera Mart. ex DC. , Inga Mill. , Gustavia L., Matisia , and Quararibea are also both dominant and species-rich groups in this area. It is remarkable that Phragmotheca centinelensis co-exists locally with several other species within the / Matisieae clade, including M. palenquiana (A. Robyns) W. S. Alverson , M. coloradorum Benoist , M. giacomettoi Romero , M. castano H. Karst. & Triana and Q. casasecae Fern. Alonso & Castrov. , Q. grandifolia (Little) Cuatrec. perhaps due to similar dispersal mechanisms or pollination syndromes. Natural regeneration of P. centinelensis seems to be rare in the forest fragments of the Centinela area. Gravity seems to be the prominent mechanism of primary dispersion. We found a high density of fruits and seeds underneath parent trees with abundant signs of predation by rodents or other small mammals, nearly all fruits with bite marks. There may be secondary dispersal due to scatter-hoarding by these mammals. The heavily armoured endocarps may be an adaptation to facilitate this, but more study is needed. Our current observations suggest a high mortality of seeds and seedlings due to a negative density dependence process via Janzen-Connell phenomena ( Forrister et al. 2019).

Conservation status.

Phragmotheca centinelensis is known from only three confirmed populations in the western foothills of the Ecuadorian Andes in the few remnants of cloud forests of the Montañas de Ila, more specifically in areas outside of Centinela Ridge (Fig. 7 ). This small population, within a 150 - ha patch of forest, represents the type locality. In this area, only three adult individuals have been observed, all of them with a diameter at breast high> 30 cm. Another subpopulation of four individuals has been reported at the southern end of the Centinela Ridge, ca. 15 km from the confirmed population. Based on field observations by other botanists, we believe there to be a second population occurring in a large fragment of forest (2500 ha) in the private Mashpi Reserve, 85 km north of Centinela (A. Pérez and G. Toasa, pers. comm.). We reviewed a sterile Phragmotheca herbarium specimen from the Mashpi Reserve and confirmed it belongs to the new species described herein. A third population is located in small patch of cloud forest at 1100–1200 m elevation, near the town of Cielo Verde in Imbabura Province, approximately 15 km north of Mashpi Reserve. This forest is part of the buffer zone from Los Cedros Reserve with approximately 4500 ha protecting the last remnants of Chocó cloud forests in western Ecuador.

Our estimates of extent of occurrence (EOO) and area of occupancy (AOO) are 520 km 2 and 16 km 2, respectively ( Bachman et al. 2011) (Fig. 7 ). Two of the three known confirmed populations of Phragmotheca centinelensis are not formally protected in the Ecuadorian Protected Area National System (SNAP). Our analysis demonstrates that, from 1990 to 2022, deforestation across the range of this species has reduced its EOO and AOO in 21 % approximately. Furthermore, based on estimated EOO and AOO (Fig. 7 ) and historic deforestation over the last 34 years, we found that 34 % of its potential habitat has disappeared. Thus, on the basis of current deforestation rates in the Chocó Region ( Finer and Mamani 2019) and habitat loss, our assessment of P. centinelensis ’ s global threat status is Endangered [EN] under IUCN Criterion EN B 1 ab (i, ii, iii) + 2 ab (i, ii, iii). It is important to note that historical deforestation of the Centinela Ridge predates the 1970 s, but several large forest fragments remained interspersed in a matrix of cacao, balsa and Gmelina L. plantations ( Dodson and Gentry 1991). However, at present, deforestation was occurring even during our visits: at the time of our floristic inventories in 2021, one of the three adult individuals which we recorded was being removed by loggers.

Etymology.

We named the new species in honour of the iconic site that the renowned botanists Alwyn Gentry and Calaway Dodson visited more than 40 years ago in the Centinela area, close to Santo Domingo de los Colorados in the western foothills of the Ecuadorian Andes. At the time they visited an area known as Centinela del Pichincha, they observed a severely fragmented landscape, which led them to conclude that ongoing deforestation had wiped out almost all the remaining forests in the region. After the publication of their seminal paper ( Dodson and Gentry 1991), the term “ Centinelan extinction ” was coined and popularised by Wilson (1992). The term aimed to reflect the global extinction of a high number of endemic plant species, many of them undescribed, following high levels of forest fragmentation.

Additional specimens examined.

Ecuador – Santo Domingo de los Tsáchilas • J. C. Cerón et al. 4684 ( QCA, QCNE, F); Parroquia El Esfuerzo, Recinto Milton Murillo, Finca del sr. Marlon Sarango . bosque siempreverde piemontano de la cordillera occidental de los Andes (BsPn 01), Fragmento de bosque intervenido rodeado de pastizales; 0°26'15.35"S, 79°13'38.57"W; alt. 840 m; 01 Nov 2023; fl • Santo Domingo de los Tsáchilas: J. C. Cerón et al. 4688 ( QCA, QCNE, F); Parroquia Centinela del Pichincha, Comunidad Santa Rosa , bosque siempreverde piemontano de la cordillera occidental de los Andes (BsPn 01), bosque maduro intervenido; 0°39'51.15"S, 79°18'48.37"W; alt. 682 m; 01 Nov 2023; fr . • Pichincha: Reserva Masphi • PDRBA 43 ( QCA); Colecciones en la parcela 7 de 60 × 60 m del transecto altitudinal para el monitoreo de la dinámica forestal. Bosque Montano Bajo . Árbol, placa 7294; 0°10'6.63"N, 78°52'34.2402"W; alt. 800–900 m; 2–25 Aug 2019. • Imbabura: Cielo Verde • PDRBA 285 (QCA); Colecciones en la parcela 7 de 60 × 60 m del transecto altitudinal para el monitoreo de la dinámica forestal. Bosque Montano Bajo . Árbol, placa 586; 0°15'26.2074"N, 78°55'6.096"W; alt. 1100–1200 m; 10–22 Jul 2021 .

Figures

Figure 1. Phragmotheca centinelensis J. C. Cerón, A. Fernández & J. E. Guevara, sp. nov. Image of the holotype at QCNE (J. C. Cerón, A. Fernández, D. Navas, & L. Narváez 4643).

Figure 2. Phragmotheca centinelensis J. C. Cerón, A. Fernández & J. E. Guevara A trunk B outer bark C inner bark. Photos of the type individual (Cerón et al. 4643) by Andrea Fernández and Juan Carlos Cerón.

Figure 3. Phragmotheca centinelensis J. C. Cerón, A. Fernández & J. E. Guevara A leaves, adaxial surface B leaves, abaxial surface C terminal branch showing the terminal bud and lenticels D basal leaf veins, abaxial surface (8 ×) E tertiary and quaternary venation, abaxial surface (8 ×) F stellate-lepidote scales, abaxial surface of leaf (100 ×) G barbate axil of mid-vein and secondary vein, with tufts of long-branched fasciculate hairs and stellate-lepidote scales, abaxial leaf surface. Photos of the type individual (Cerón et al. 4643) by Andrea Fernández and Juan Carlos Cerón.

Figure 4. Phragmotheca centinelensis J. C. Cerón, A. Fernández & J. E. Guevara A flowering branch B flower with reflexed, concave-spoon-like petals C campanulate flowering calyx D distal part of petal showing the diagnostic concave form that is characteristic of this new species E flower bud (8 ×) F close-up of flower bud indument, a mix of stellate-lepidote scales and fasciculate hairs G apical lobes of staminal column (note sterile tips), each with two parallel rows of thecae and the shorter style in centre H close-up of apical lobes with elongate, foveate thecae (15 ×); I elongate, septate hairs on the thecae (100 ×).

Figure 5. Phragmotheca centinelensis J. C. Cerón, A. Fernández & J. E. Guevara A fruiting branch B patelliform fruiting calyx C apex of the fruit showing the fine longitudinal fissures D longitudinal view of the fruit showing yellow exudate from the mesocarp E transverse section of the fruit showing the exocarp, fibrous mesocarp and very thick endocarp tissue surrounding the seeds F two pyrenes (seeds with some residual fibrous-woody endocarp and mesocarp tissue).

Figure 6. A Distribution of Phragmotheca centinelensis J. C. Cerón, A. Fernández & J. E. Guevara, its relatives in the Chocó Region of Ecuador and Colombia and two morphologically similar Amazonian species B cloud-forest habitat of the new species in Ecuador.

Figure 7. Map showing the Extent of Occurrence (EOO), Area of Occupancy (AOO) and available habitat of Phragmotheca centinelensis J. C. Cerón, A. Fernández & J. E. Guevara in western Ecuador. Inset: Location of Santo Domingo de las Tsáchilas Province within Ecuador.