Nasa ojedae Cornejo & Weigend

Cornejo, Xavier & Weigend, Maximillian, 2024, Nasa ojedae (Loasaceae): A new species from the montane forests of Reserva El Corazón, western Andes of Ecuador, Phytotaxa 642 (2), pp. 201-207 : 202-206

Nasa ojedae Cornejo & Weigend , sp. nov. ( Figs. 1–3 )

This new species of Nasa is a biennial herb with yellow corollas and white arachnoid indument, similar to N. profundilobata (Werderm.) Weigend but differing from it and from all species of the N. ranunculifolia group by the ovaries with five (vs. three) placentae and the fruits opening by five (vs. three) apical valves, and the seeds with alveolate (vs. reticulate) sculpture.

Type:— ECUADOR. Chimborazo: Reserva El Corazón , 2°03’ S, 78°54’ W, 2600 m, 20 Aug 2022 (fl, fr), X. Cornejo & J. Josse 10058 (holotype: GUAY!; isotype QCA!) .

Stout biennial herb c. 2 m tall, stem to c. 1.5 cm thick; plant covered with brown stinging setae, 2–3 mm long, and shorter glochidiate trichomes, 0.2–0.5 mm long, and initially flat-filiform, twisted hyaline trichomes, then forming a white arachnoid indument. Terminal young shoots with a thick arachnoid white indument of foamy appearance. Leaves alternate; petioles to c. 17 cm long, suberect to ascending, spreading at the lower half of the plant, inserted at base of lamina and sometimes peltate to c. 1 cm from leaf margin at base, densely covered with erect hyaline glochidiate trichomes, 0.2–0.5 mm long, and translucent light brown setae, c. 3 mm long; lamina widely ovate to pentagonous, 14–40 × 12–40 cm, the base truncate to cordate, the sinus up to c. 3 cm deep, margins dentate to subpalmately lobed, the lobes 3 on each side, broadly triangular, 2–5 × 2.5–7 cm, adaxial and abaxial surfaces covered with setae c. 3 mm long and glochidiate trichomes, 0.2–0.5 mm long; leaf venation palmate, with 5–7 costae arising near base, tertiary veins sulcate above (fresh), all veins prominent beneath (fresh). Flowers supraxillary in terminal forked, frondose, erect monochasia 12–40 cm long, bearing 3 to 5 suberect flowers, bracts absent. Pedicels c. 5 cm long, setose. Calyx cup-shaped, c. 1.3 × 1.7 cm, very densely light brown setose and with erect white glochidiate trichomes, lobes erect, ovate to ovate-lanceolate, 1.7–2.5 cm long, fused for ⅓ to ½ of the length, the base setose, abaxially faintly veined and with densely arranged white glochidiate trichomes, adaxially with abundant white glochidiate trichomes, the apex acuminate, the tip glandulose. Corolla bowl-shaped, petals 5, imbricate at anthesis, obovate, 3.5–3.8 × 2–2.6 cm, the apex rounded, sulfur-yellow, esetulose, abaxially with short (0.2–0.3 mm long), erect trichomes, adaxially glabrous. Nectar scales with rectangular back, c. 5 mm long, with 2 to 4 obovoid to oblong sacs near base on back, 3–4 × 1.5–2.5 mm, scale neck thickened, 3-lobed, laterally protracted into two stiffly erect, vertical wings 6–8 × 1.5–2 mm. Staminodia 2 per scale, linear, 10–15 mm long, densely and shortly pilose. Stamens numerous, in 5 epipetalous fascicles of 10 to 20 each, filaments 13–22 mm long, anthers 1.5–2 × 0.8–1 mm, brownish or light brown to grey. Style stout, c. 2.2 cm long in carpellate phase. Ovary inferior, unilocular, with 5 parietal placentae. Capsules broadly elliptic, c. 3.2 × 2.3 cm, with abundant, white glochidiate trichomes, crowned by a persistent calyx, opening with 5 apical valves, pedicel ca. 5.5 cm long. Seeds obovate, 1.2–1.5 × 1 mm, alveolate.

Discussion:— Nasa ojedae is clearly most similar to Nasa profundilobata and can be assigned to the informal N. ranunculifolia group within Nasa ser. Grandiflorae . This is a morphologically rather well-defined group of biennial to perennial herbs or small shrubs, restricted to the higher elevations of the Andean mountain range, generally found well above 3000 m ranging to nearly 5000 m in elevation ( Weigend & Gottschling 2006, Henning 2011). The Nasa ranunculifolia group is also characterized by palmate to peltate leaves and stiff erect lateral wings on the nectar scales ( Urban 1886, Urban & Gilg 1900, Henning et al. 2011). However, Nasa ojedae is unique and differs from all other species in the N. ranunculifolia group by having ovaries with 5 parietal placentae and fruits apically opening by 5 valves (vs. flowers with 3 parietal placentae and fruits opening by 3 valves). The group comprises several biennial species: Nasa magnifica (Weigend 2006: 77) , with pale pink flowers and red-and-white nectar scales from the western Andean slope of Peru, Nasa tulipadiaboli T. Henning & Weigend (2011: 61) with yellow flowers with very narrow and pointy petals from the eastern Andes of Peru, and Nasa profundilobata from Ecuador. Only Nasa profundilobata shares the presence of rounded, yellow petals and arachnoid pubescence, but differs from N. ojedae in ovaries with three placentae and fruits with three valves, like all other species of this group. Also, the leaves of Nasa profundilobata are very deeply lobed with lobes longer than wide, not widely triangular as in N. ojedae .

Etymology:—The epithet honors Mr. Luis Ojeda and his family, by whose initiative and love for nature a patch of Andean forests on the property in El Corazón is conserved.

Common names:—Ortiga.

Habitat and distribution:— A robust, biennial herb in montane Andean wet forests, persisting in forested ravines and secondary forests on well-drained soils, c. 2600 m elevation at the Reserva El Corazón, at southernmost tip of northern Andean block. In the type locality, Nasa ojedae is flowering at same time with the sympatric N. humboldtiana subsp. humboldtiana , a species recently rediscovered by the senior author 162 years after the type collection was gathered by Richard Spruce, in Aug 1859 ( Henning et al. 2023). At present, both endangered taxa are only known by less than 5 individuals at the Reserva El Corazón.

Phenology: — Based on field work carried out from November 2020 to November 2023, flowers and immature fruits were observed on the same individual from August to November, the mature fruits were found in January.

Preliminary conservation status:— Nasa ojedae is known only from the type, which was collected in the Reserva El Corazón, in the Andean province of Chimborazo. As the area of occupancy of the species is (dramatically) less than 100 km 2 and due to the steady deforestation and fragmentation in the region, with only small patches of native vegetation remaining, surrounded by crops (pers. obs.), it is suggested that this new species should be assigned as Critically Endangered ( CR) following the IUCN criterion B 1 ab(iii) ( IUCN, 2022).

Figures

FIGURE 1. Distribution map of Nasa ojedae (*).

FIGURE 2. Nasa ojedae. A. Flower at anthesis, lateral-adaxial view; B. Flower at anthesis, lateral view, inner floral nectary at lower right corner; C. Two detached petals and epipetalous fascicles of stamens attached to base, inner view; D. Fruit nearly to maturity with persistent sepals, lateral view; seeds preserved in alcohol at upper left corner and fruit transversal section exhibiting 5 parietal placentae at lower right corner; E. A mature basal leaf blade, adaxial view; F. Habitat, an Andean forested ravine (A–F, based on X. Cornejo, J. Josse 10058, the type). Photos by Xavier Cornejo.

FIGURE 3. Nasa ojedae. A. Whitish indument; B. Arachnoid trichomes; C–D. Stinging setae, close up of glandular base at upper right corner; E. Leaf blade beneath; F. Glochidiate trichomes (A–F, based on X. Cornejo & J. Josse 10058, the type). Photos by Xavier Cornejo.