Peperomia riosaniensis Hutchison ex Pino, Samain & L.E. Alomia, 2023

Pino Infante, Guillermo Eloy, Samain, Marie-Stephanie, Alban Castillo, Joaquina Adelaida & Alomia Collazos, Luis Enrique Aaron, 2023, Species of Peperomia (Piperaceae) from the Sana River Valley, Peru, PhytoKeys 225, pp. 1-40 : 1

12. Peperomia riosaniensis Hutchison ex Pino, Samain & L.E. Alomia sp. nov.

Fig. 8A-H

Type material.

Peru, [dept. Lambayeque, prov. Chiclayo, dist. Oyotún]: road to Hacienda Taulis, ca. 80 km up the Río Saña from the Pan American Highway, 500 m, [06°51'23"S, 79°09'31"W], 28 Aug 1964, P. C. Hutchison 6308 (holotype: UC[1298471]!, isotypes US [2485139]!, USM [Not found]).

Diagnosis.

Perennial, succulent terrestrial herb similar to P. palmiformis Pino & Samain, differs in inflorescences that have wider panicles, with more (30-60 compared to 16-40) and shorter spadices (1-5 cm long compared to 2-8 cm long), leaves attached all along the stem, slightly longer (6-9 cm compared to 5-7 cm), more succulent, canaliculate instead of flat, with longer petioles (2 cm compared to 0.7 cm), lamina wider at proximal third (1.2-1.8 cm compared to 0.5-1.2), margin entire distally instead of serrate, fruits larger (0.9 × 0.6 mm compared to 0.4 × 0.3 mm), widely ovoid instead of narrowly ovoid.

Description.

Perennial, succulent, terrestrial herb, living in gorges or the shade of other plants, (4-) 9-18 cm tall, up to 50 cm tall when flowering. Roots fibrous, light gray, 0.7-0.4 mm diam., 2-4 cm long. Stem mainly erect or shortly decumbent at base, straight, terete, slightly puberulous, 0.7-1.2 cm diam. at the base, gradually tapering to 4-8 mm at the apex, bright green, brownish at the base, with reniform leaf scars spirally displayed every 3-8 mm, 1.5-2 mm × 3-4 mm, brownish; very rarely branching dichotomously from the distal 10 cm, but mostly with 4-6 branches from the base, resulting in a caespitose plant. Leaves alternate, glabrous, spirally inserted, present all along the stem or in the distal third of the main stem or branches under dry conditions, young leaves smaller, narrower, very succulent, induplicate or canaliculate, older leaves less succulent; petiole reniform in section, gradually continuing with leaf, 0.5-2 cm long, 2.5-3 mm wide, 1.5-2 mm thick, lamina convex to induplicate, narrowly obovate, (3-) 6-9 cm long, 1.2-2.4 mm thick, (1.4-)2-3 cm wide at distal third, (1.4-)1.8-3 cm wide at the middle, (1-)1.4-1.8 cm wide at proximal third, apex subacute, distal third slightly recurved, base cuneate; adaxially bright glossy green, convex to slightly induplicate, obscurely 3-5-palmatinerved, nerves lighter colored; canaliculate or markedly induplicate, only the central nerve is visible in young leaves; margin entire; abaxially pale green, obscurely 3-5-palmatinerved, central nerve subcarinate, the others rather depressed. Inflorescence is an open terminal panicle with 30-60 alternate spadices emerging solitary or from secondary axes with 2-7 spadices, each born from 10-20 nodes appearing 5-10 cm from the base of the central axis; each node with a basal lanceolate acute bract 0.4-2 cm long, 0.3-0.7 cm wide, bright green; central axis 30-40 cm long, 3-6 mm diam. at the base, gradually tapering to 1 mm, terete, longitudinally furrowed, very light green; peduncle terete or slightly funnel-shaped distally, 3-10 mm long, 0.7-1.2 mm diam., each with a 2 mm long, 0.5 mm wide oval bract at the base, deciduous; rachis 1-5 cm long, 1.2-1.6 mm diam., light green. Floral bracts broadly oval to round, subacute, light green, 0.5-0.6 mm diam. Stamens, filaments 0.4 mm long, 0.2 mm diam., transparent, anthers white ovoid, 0.4-0.5 × 0.3 mm. Fruit an ovoid berry, 0.85-0.9 mm long, 0.55-0.6 mm diam., bright brown to olive green, minutely papillate, pedicel inconspicuous, dry anthers attached, style prominent, ovoid, bright brown, 0.15-0.2 mm long, 0.15-0.2 mm diam., stigma lighter colored.

Distribution and habitat.

Plants grow from 450 to 600 m, the lowest and driest layer of the area studied, along the Saña valley between the towns of Oyotún and La Florida in the departments Lambayeque and Cajamarca, on rocky soil, in thickets shaded by shrubs and supplied with moisture from nearby water courses.

Phenology.

Inflorescences appear from June to August; fruits ripen from July to September.

Etymology.

The epithet was coined by Hutchison in 1967 after the Saña river, “Río Saña” in Spanish, which is Latinized to “riosaniensis” in the same way Rauhocereus riosaniensis was described by Backeberg. As Hutchison only labeled the herbarium sheets and never published this name it has been considered a nomen herbariorum ( Mathieu 2007).

Notes.

The closest species of Peperomia riosaniensis is P. palmiformis Pino & Samain ( Pino et al. 2012) The web page “Peperomia.net” (http://www.peperomia.net/repertorysearch.asp) indicates that this taxon is merely a synonym of the latter. We compared both species in detail and the main differences between P. riosaniensis and P. palmiformis are resumed in Table 3 .

While P. palmiformis grows from 800 to 900 m along the Utcubamba valley from Bagua to Pedro Ruiz in department Amazonas, Peru, P. riosaniensis grows 300 m lower. Nevertheless, the temperatures in the habitats of both species average 25-30 °C during the day and 18-22 °C at night, P. riosaniensis grows at 200 km distance from P. palmiformis , on the dry, xerophytic western slopes of the Andes, with 25 mm rain per month average in summer and 0-4 mm in winter (Clima.com: https://www.clima.com/peru/cajamarca/florida). Peperomia palmiformis lives on the flatter eastern slopes of the Andes, along the lower basin of the Utcubamba river, in a dry valley but already under the influence of the Amazon Forest, with nearly 60 mm rain per month in summer and 5 mm monthly in winter (Clima.com). Both species look similar from far away, but P. riosaniensis is slightly shorter when vegetative; its inflorescences have relatively wider panicles, with more horizontal branches and more spadices that are relatively shorter. Although leaves look very much alike when pressed, the new species has longer and thicker petioles, longer leaves that are not as narrow and succulent, wider at the proximal third, making its margin convex, compared to the concave margin of P. palmiformis at this segment. The new species also has induplicate or canaliculate leaves, adaxially slightly darker and glossier, frequently carinate beneath and slightly recurved at the distal third, compared to the straight, flat, mostly biconvex succulent leaves of P. palmiformis , mainly due to its more developed fenestra. The serrate distal margin of the leaves observed in P. palmiformis similar to P. erosa Hutchison ex Pino ( Pino et al. 2012) has never been observed in the new species. Fruits are entirely different, more globular, larger, thicker, and papillate in P. riosaniensis , frequently with dry anthers attached, and lacking the conspicuous bright orange persistent basal pedicel. Peperomia palmiformis fruits also have a larger, bright orange style, with a bulge that is sometimes even thicker than the fruit itself. These morphological differences are supported by the fact that in a recent phylogenetic study, P. riosaniensis is located in a different branch from P. palmiformis that is more related to P. columella , P. ferreyrae , P. mathieui , and P. columnaris from the Utcubamba valley ( Frenzke et al. 2015). All these species mentioned belong to Peperomia subgenus Fenestratae Pino ( Frenzke et al. 2015).

Additional specimens were examined.

Peru, dept. Lambayeque, prov. Chiclayo, dist. Oyotún: road from Oyotún to El Espinal, on the trail to waterfall Velo de la Novia, 515 m, 06°48'30.3"S, 79°11'08"W, 26 Jul 2020, G. Pino & L.E. Alomía 3237 (USM 330870); same road, 520 m, 06°48'27.4"S, 79°11'04.7"W, 26 Jul 2020, G. Pino & L.E. Alomía 3238 (USM 330871); Dept. Cajamarca, prov. Santa Cruz, dist. Catache: Road from El Espinal to La Florida, 582 m, 06°51'13.7"S, 79°09'16.5"W, 26 Jul 2020, G. Pino & L.E. Alomía 3230 (USM 330869); Road from Cayaltí to La Florida, 8.4 km from La Florida, 492 m, 06°50'51,6"S, 79°09'53,7"W, 1 Mar 2009, G. Mathieu & L. Symmank 2009-167 (BR, GENT, USM 258833!) Same road, 591 m, 06°51'13.4"S, 79°09'18.4"W, 28 Aug 2022, G. Pino et al. 3637 (USM 330882) prov. San Miguel, dist. La Florida, Puente el Papayo, on slopes at the borders of the roadside, 18 Jul 1982, S. Llatas Quiroz 861 (F 1931956, NY).

Figures

Figure 8. Peperomia riosaniensis Pino, Samain & L. E. Alomia, sp. nov. A, B plant in habitat C plant ex situ D early stages of development E detail of the leaves F young plant in cultivation G spadix in anthesis H mature spadix with fruits I comparison of the fruits of P. riosaniensis (above) and P. palmiformis (below).