Sciodaphyllum pygmaeum Jiménez-Mont. & Idárraga.

Jiménez-Montoya, Jáider, Pizano, Camila & Idárraga-Piedrahíta, Álvaro, 2021, A new species of Sciodaphyllum (Araliaceae) from the Chocó Biogeographical region in Colombia, Phytotaxa 491 (2), pp. 184-190 : 184-188

Sciodaphyllum pygmaeum Jiménez-Mont. & Idárraga. , sp nov. ( Figs. 1–2 )

Type: — COLOMBIA. Valle del Cauca. Dagua, Cuenca del Río Anchicayá , elev. 609 m, 3°34’29.5’’ N, 76°52’39.3’’ W, 15 September 2018, A . Idárraga , J . Jiménez , L . Clavijo & A . Zuluaga 6812 (holotype ICESI!; isotype JAUM!) .

Diagnosis:— Sciodaphyllum pygmaeum differs from S. minutiflorum ( Harms 1908: 153) Lowry et al. (2019a: 10) by having hollow branches (not solid branches), leaflets 3–5 (not (6–)7–9), poorly reticulate venation abaxially in sicco (not prominent reticulate), stipular ligules (3–) 3.5–6.8 cm long (not 7–13 cm long), tubular (not connation of the margins), glabrous (not tomentulose, glabrescent) and not canaliculated abaxially (canaliculated abaxially), primary axis of the inflorescence 2.2–14.6 cm long (not 15–40 cm long), and secondary axes of inflorescence 5–11 (not 24–66), 4.3–12.2 cm long (not 20–53 cm long).

Shrub, 1.2–3.7 m tall, monocaulous, sometimes prostrate, terrestrial or epiphytic, hermaphrodite; branches hollow, slightly lenticellate. Plants glabrous or glabrescent, with a sericeous indument; trichomes up to 0.3 mm long, appressed and whitish. Stipular ligule (3–) 3.5–6.8 cm long, long-triangular, tubular, apex straight to convex, glabrous, without lenticels, not canaliculated abaxially, persistent or caducous. Leaves palmately compound, with 3–5 leaflets, arranged in a single whorl; petioles 30–52 cm long, teretes, slightly thickened at both ends, lenticels absent or few along the petiole; basal petiolules (1–)1.2–2.8(–3.4) cm long, median petiolules (4.7–)7–11.8(–13.3) cm long, teretes, thickened at both ends, canaliculate in sicco; blades 14.4–44 × 4.5–16 cm, elliptic or occasionally ovate, base acute, convex, occasionally cuneate or rounded, margin entire, apex acute, acuminate, acumen 1.2–2.2(–2.5) cm long, symmetrical or slightly asymmetrical, held horizontally or semi-erect, lustrous on both surfaces. Venation pinnate, prominent on both surfaces; secondary veins 16–30(–33), slightly brochidodromous, prominulous on both surfaces, irregularly spaced; inter-secondary veins present; tertiary veins mixed percurrent, obtuse or perpendicular to the midvein. Inflorescence a panicle, terminal, lilac-magenta; primary axis 2.2–14.6 cm long; with 5–11 secondary axes, 4.3–12.2 cm long, irregularly spaced; the proximal secondary axis bract 1.1–3 cm long, triangular or occasionally deltate, apex acute to obtuse, the other secondary axes bracts 0.8–3 mm long, deltate, apex acute; peduncles 24–64 per axis, (0.6–) 0.8–2.4 mm long, irregularly spaced, usually thickened; ebracteate; ultimate inflorescence units umbels, each 5–9-flowered, the pedicels (0.9–) 1–5.3 mm long; ebracteate. Hypanthium 0.8–1.8 × 0.8–1.9 mm, densely indumented; calyx rim 5- dentate, teeth 0.34–0.5 mm long; corolla 0.9–1.8 × 1.5–2 mm, calyptrate, mucronate or not at apex, slightly fissured between petals internally, petals separating 0.3–0.6 mm at base when the calyptra is shed; stamens 5, filaments 1.7–2.5 mm long, whitish-lilac, anthers 0.7–1.1 × 0.5–0.7 mm, ovate or obovate, reniform in lateral view, sub-dorsifixed insertion, purple, pollen white; disk short-conical, crenulate; 5 styles, 0.35–1.05 mm long, connivets forming a column; ovary 5-carpellate. Fruits drupaceous, 4.7–7.8 × 4.7–7.3 mm, globose, fleshy; styles recurved; pyrenes 3.2–4.5 × 2–2.5 mm, laterally flattened.

Distribution and habitat: — Sciodaphyllum pygmaeum is known from a wet tropical forest ( Holdridge 1971) in the basin of the Anchicayá River in the Chocó Biogeographical region, in the municipalities of Buenaventura and Dagua in the department of Valle del Cauca in Colombia ( Fig. 3 ), at the elevation of 600– 770 m. This species is an occasional component of the understory of well-preserved forests of the region.

Phenology: —The specimens collected in September of 2018 presented different phenological states (flower buds, flowers, and fruits). Additional collections and observations made by the Universidad Icesi staff working in the area, recorded flowering between October and December (O. Díaz et al. 1821 (ICESI); O. Díaz, pers. comm.). Therefore, it appears that the species blooms and fruits throughout the year. Although we were not able to collect extensive data on plant-animal interactions, during field work we saw insects visiting the flowers and birds eating the fruits and seeds.

IUCN Red List Category:— This species can be considered under the category of Least Concern (LC; B1, B2), according to IUCN Red List categories and criteria ( IUCN 2012) and using the R packpage “ConR” ( Dauby 2019; Protected Planet 2019; R Core Team 2019). Based on available data from plant collections, only one population is registered in one single locality, with an extent of occurrence (EOO) and an area of occupancy (AOO) of 4 km 2. These two measurements are the same, because we have so far only found one plant population. However, although the species has low EOO and AOO and is only known from one locality, the studied population grows partially within the conservation area of the Farallones de Cali National Natural Park ( IDEAM 2016), which is protected by the Colombian law. Furthermore, the species was found in a largely forested area with no deforestation or other anthropogenic pressures, where we suppose other populations of the species may exist. Due of the reason stated above we consider that the species is at low risk.

Etymology: —The epithet “ pygmaeum ” refers to the Latin pygmaeus, meaning dwarf, alluding to the dimensions of the plant and its inflorescence, which are generally smaller when compared with other species in the Minutiflorae group.

Additional specimens examined (paratypes): — COLOMBIA. Valle del Cauca. Buenaventura, corregimiento El Danubio, Central Hidroeléctrica Alto Anchicayá , sector La Loca, parcela 2 de 0.1 ha, elev. 767 m, 3°34’38.3’’ N, 76°53’03.6’’ W, 17 October 2019, O . Díaz et al. 1821 ( ICESI). Dagua, Cuenca del Río Anchicayá , elev. 722 m, 3°34’33.8’’ N, 76°52’58.2’’ W, 15 September 2018, J . Jiménez et al. 2401 ( CUVC, HUA); Cuenca del Río Anchicayá , elev. 722 m, 3°34’33.8’’ N, 76°52’58.2’’ W, 15 September 2018, J . Jiménez et al. 2408 ( JAUM, MO); Cuenca del Río Anchicayá , elev. 722 m, 3°34’33.8’’ N, 76°52’58.2’’ W, 16 September 2018, J . Jiménez et al. 2411 ( COL, HUA); Cuenca del Río Anchicayá , elev. 722 m, 3°34’33.8’’ N, 76°52’58.2’’ W, 17 September 2018, J . Jiménez et al. 2412 ( ICESI, JAUM) .

Discussion: —The new species, Sciodaphyllum pygmaeum , is related to species of the informal group Minutiflorae ( Plunkett et al. 2005, Frodin et al. 2010). Species in this group are morphologically characterized by being unbranched or occasionally sarmentose shrubs, covered with sericeous, appressed, and whitish indument, that is denser in the hypanthium and very common in the inflorescence axes and the stipular ligule, and the hairs are simple and straight. The leaflets are arranged in a single whorl and are generally glabrous. The inflorescence is a terminal panicle, purplelilac-magenta, generally ebracteate or with small bracts, or rarely with one large proximal secondary axis bract. The terminal inflorescence units are arranged in umbels (rarely heads), and the flowers are pentamerous with a minute dentate calyx, a calyptrate corolla with the petals separating at the base when the calyptra is shed, purple ovate anthers, flat short-conical or concave ovary disc, and free but connivent styles. The fruits are globose with patent styles. This subgroup includes five species, i.e., Sciodaphyllum breviramum (Jiménez & Idárraga 2018: 319) Jiménez & Idárraga in Lowry et al. (2019a: 7), S. elachistocephalum ( Harms 1938: 110) Lowry, Plunkett & Mora in Lowry et al. (2019a: 8), S. magnifolium ( Cuatrecasas 1946: 544) Lowry et al. (2019a: 9) , S. minutiflorum , and S. sandianum ( Harms 1908: 153) Lowry et al. (2019a: 12) .

Sciodaphyllum pygmaeum differs from the other members of Minutiflorae group by its hollow branches, a tubular stipular ligule, the length of median petiolule (2.5–)4–6(–7.5) times longer than the basal ones, and the fewer number of branches in the inflorescence. Morphologically, S. pygmaeum is most similar to S. minutiflorum , but the dimensions of the plant leaves and inflorescence of S. minutiflorum are larger than those of S. pygmaeum , and the number of leaflets and of the inflorescence branches is also higher in S. minutiflorum , as indicated in the diagnosis.

Sciodaphyllum minutiflorum is a species described from Moyobamba in the department of Loreto ( Peru), at elevation of 1500–1600 m, and registered in Peru, Ecuador, and Colombia. After a careful examination of the specimens from Colombia, it is concluded that the natural distribution for this species in the country is across the Andean Cordillera region at elevation of 1400–2500 m, in premontane wet forest (bh-PM), premontane moist forest (bmh-PM), wet low montane forest (bh-MB), and moist low montane forest (bmh-MB; Holdridge 1971).

Figures

FIGURE 1. Sciodaphyllum pygmaeum. A. Branch with leaves and inflorescence. B. Stipular ligule. C. Basal leaflet adaxially (left) and median leaflet abaxially (right). D. Detail of the petiolules and leaflets position. E. Basal bract. F. Floral umbel. G. Flower initiating anthesis (side view). H. Flower after calyptra is shed (top view). I. Calyptra in top view. J. Open flower with pedicel. K. Secondary axis fructified. L. Umbel with fruits. M. Disk of the ovary in fruit. [Illustrations by A. Sanín].

FIGURE 2. Sciodaphyllum pygmaeum. A. Branch with leaves and inflorescence. B. Leaflets position and abaxial surface of the blades. C. Stipular ligule. D. Detail of the inflorescence. E. Floral umbel and flowers. F. Fruiting umbel. [Photos by J. Jiménez].

FIGURE 3. Distribution map of Sciodaphyllum pygmaeum.