Rhodospatha rubrinervis M. Cedeño, O. Cubero & O. Ortiz, 2025
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publication ID |
https://doi.org/10.3897/phytokeys.260.154762 |
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https://doi.org/10.5281/zenodo.16539661 |
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persistent identifier |
https://treatment.plazi.org/id/EA9857B1-5EF0-598E-92CA-8378040EB4BB |
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scientific name |
Rhodospatha rubrinervis M. Cedeño, O. Cubero & O. Ortiz |
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sp. nov. |
Rhodospatha rubrinervis M. Cedeño, O. Cubero & O. Ortiz sp. nov.
Figs 1 View Figure 1 , 2 View Figure 2 , 3 View Figure 3
Type.
Costa Rica • San José: Cantón Pérez Zeledón, distrito de Rivas, San Gerardo, Cloudbrige Nature Reserve , 1800 m elev., 26 Apr 2023, O. Cubero, M. Rodríguez-Arias & M. Cedeño 005 (holotype: USJ!; isotype: CR!) .
Diagnosis. Rhodospatha rubrinervis is similar to Rhodospatha forgetii N. E. Br. (Fig. 4 A – M View Figure 4 ), but differs in having internodes 1–7 cm long, salmon-coloured dark green or light green (vs. 6–8 cm long, dark green), petiole green at the base with a conspicuous longitudinal bright pink band or line abaxially towards the geniculum (vs. petiole light green without band or line abaxially, Fig. 5 B View Figure 5 ), geniculum bright pink or dark purple, sometimes with green dots (vs. geniculum grooved always green, Fig. 5 D View Figure 5 ), leaf blades light green with lilac and white punctations on the lower surfaces (vs. light green with white punctations, Fig. 5 E View Figure 5 ), mid-rib bright pink up to the apex (vs. constantly green, Fig. 5 C View Figure 5 ), primary lateral veins bright pink up to the middle and green from the middle to margin (vs. green along the whole length, Fig. 5 C View Figure 5 ), spathe-subtending bracteole reddish with constriction line near the margin (vs. pinkish without constriction line, Fig. 6 A – F View Figure 6 ); spathe brownish-bright pink externally during development, bright pink externally and internally at anthesis (vs. brownish-orange externally during development, Fig. 4 A View Figure 4 , pale pink externally and internally at anthesis, Fig. 4 B, J, N View Figure 4 ), spathe up to 15.3 cm longer than the spadix and deciduous (vs. up to 6 cm longer than the spadix and marcescent, Fig. 5 A View Figure 5 ), stipe red to bright pink, up to 1.7 cm (vs. brown, sessile or stipitate up to 6 mm, Fig. 4 C View Figure 4 ), spadices pinkish during development and anthesis (vs. lilac during development and pinkish at anthesis, Fig. 4 C, D, F View Figure 4 ), stamens with pinkish laminar filament (vs. creamy-white, Fig. 4 H View Figure 4 ) and ovary with up to 30 ovules per locule (vs. up to 40 ovules, Fig. 5 F View Figure 5 ).
Description.
Robust nomadic vine, appressed-climbing. Seedlings: unknown. Juvenile plants: terrestrial appressed; stem cylindrical, shiny and smooth, dark green or dark purple, with light green dots; internodes 3–7 cm long and 7–9 cm diam.; petiole smooth, 7–30 cm long, light green changing to bright pink at the base and near to the geniculum; petiole sheath persistent; geniculum bright pink with green dots; leaf blades 12–25 × 4.5–8.0 cm, lanceolate to elliptical, non-equilateral, acute to narrowly rounded at the base and long acuminate at the apex, reddish to pinkish when new, changing to shiny dark green in the upper surface and light green in lower surface, decurrent on geniculum; mid-rib sunken adaxially, convex abaxially and bright pink; primary lateral veins bright pink; margin with a reddish line on the edge. ADULT PLANTS: root climbers and branching, growing up to 7 m above ground; stem cylindrical or slightly flattened, shiny, smooth, dark green, light green sometimes and becoming salmon-coloured in some areas; internodes 1–7 cm long, 7–9 cm in diam.; anchor roots light green and sometimes green mixed with purple; feeder roots light green and sometimes green mixed with violet; petiole 24–71 cm long, smooth, dark green at the base and mostly becoming light green, with a conspicuous longitudinal bright pink band or line abaxially up to geniculum, sometimes with small salmon-coloured areas mainly in new leaves; sheathed to base of geniculum; petiole sheath persistent or sometimes becoming deciduous with fibrous remnants; geniculum 2–6 cm long, dark purple sometimes with green punctations, sunken adaxially, convex abaxially; leaf blades 33–82 × 12–30 cm, oblong or lanceolate to elliptical, non-equilateral, subcoriaceous, cuneate to attenuate at the base, acuminate at the apex, shiny dark green above and light green below with lilac and white punctations, decurrent at geniculum, drying blackish- or greenish-yellow with reddish-bright pink primary lateral veins; mid-rib bright pink, sunken adaxially, convex abaxially; primary lateral veins 24–29 per side, bright pink up to the middle and green from the middle to margin, sunken adaxially, prominent abaxially; interprimary veins prominent and parallel towards margin, in young blade primary and interprimary veins intense bright pink; collective vein not visible; margin undulate and sometimes reddish. INFLORESCENCES on ascending stems, several simultaneously in flowering season, arranged in leaf axils or within a green cataphyll; peduncle smooth, reddish, 19–25.5 cm long, 2–4 mm diam.; bracteole subtending spathe (not peduncle) 1.0–1.5 × 1.7–2.0 cm, reddish with constriction line near to margin; spathe acuminate to acuminate, 28–38.5 cm long, 6–9 cm wide, brownish-bright pink externally during development, bright pink externally and internally at anthesis, up to 15.3 cm longer than spadix, membranous, completely open, with overlapping margins at base, deciduous a few hours after opening; stipe bright red to bright pink up to 1.1–1.7 cm.; spadix 18.8–23.2 cm long, 4.4–5.3 cm in diam., cylindrical and weakly tapered to apex, pinkish during development and anthesis, with red sterile region at apex, with 19–21 flowers in principal spiral and 11–12 in secondary spiral, flowers 5–6 mm long; stamens 1.5 to 5.0 mm long, with pinkish laminar filaments; anthers 0.5 to 1.0 mm long; ovary quadrangular in longitudinal section, 2–3 × 1.3–2.0 mm, bilocular with up to 30 ovules per locule, borne on axillary placentas; style quadrangular or hexagonal, 2.0–2.5 × 1.8–2.0 mm; stigma linear with transparent stigmatic secretion; berries white and pinkish, seeds light brown, reniform.
Etymology.
The species epithet “ rubrinervis ” refers to the distinctive reddish colouration of the mid-rib and primary lateral veins. This striking venation not only serves as a key diagnostic character in the field, but also highlights the aesthetic appeal and uniqueness of the species within the genus Rhodospatha .
Distribution and ecology.
This species is endemic to Costa Rica, occurring in the region of Pérez Zeledón on the Pacific slope of the Cordillera de Talamanca, and in Bosque Tropical Nuboso Palo Verde on the Caribbean slope. It grows in cloud forests and premontane rain forest life zones, in mature secondary forest, at around 1800 m elevation.
Phenology.
Flowering time from March to June; fruits have been recorded in September and October.
Conservation status.
The recent collections of Rhodospatha rubrinervis reported here come from two localities within a protected area (Cloudbridge Nature Reserve and Bosque Tropical Nuboso Palo Verde, Costa Rica). Further information on the species’ distribution and population status is needed to enable more accurate conservation assessment. Rhodospatha rubrinervis is, therefore, currently considered as Data Deficient (DD).
Discussion.
Rhodospatha rubrinervis is characterised as follows: juvenile plants with internodes dark purple with light green dots; petiole sheath persistent, light green and bright pink at base; adult plants with internodes bright green, sometimes displaying small salmon-coloured areas; petiole sheath persistent; geniculum dark purple or bright pink; mid-rib bright pink; primary lateral veins bright pink up to the middle, becoming more intense in new emerging leaves; peduncles and bracteoles bright pink; spathes brownish-bright pink during development and bright pink both externally and internally at anthesis, up to 15.3 cm longer than spadix; stipe bright pink; spadix lilac with strongly pigmented pink sterile region at apex; 19–21 flowers arranged in main spiral and 11–12 in alternate spiral; stamens with pinkish laminar filaments; berries white to pinkish, seeds and reniform, light brown.
In addition to the differences cited in the diagnosis, another important feature distinguishing Rhodospatha rubrinervis and R. forgetii lies in their growth pattern: R. rubrinervis has a greater abundance of leaves and shows the ability to branch and spread more widely on the host tree than R. forgetii , which rarely branches. Additionally, juveniles of R. rubrinervis are more frequently found on the forest floor than those of R. forgetii .
Rhodospatha rubrinervis could be also confused with Rhodospatha wendlandii Schott , but differs in having oblong or lanceolate to elliptical blades with 24–29 primary lateral veins that are bright pink up to the mid-point (vs. oblong-oblanceolate blades with 28–52 primary lateral veins, all green), bright pink mid-rib up to the apex (vs. entirely green mid-rib), reddish bracteole with a constriction line near the margin (vs. cream or white bracteole without constriction line); brownish-bright pink spathes externally during development, bright pink externally and internally at anthesis (vs. white to creamy throughout development and anthesis) and bright red to bright pink stipes (vs. white or cream).
Juveniles of Rhodospatha rubrinervis may also be confused with those of R. bogneri Croat ; however, R. rubrinervis can be distinguished by having a membranaceous leaf blade (vs. coriaceous), with undulate, reddish margins (vs. entire margins), a long-acuminate apex (vs. short-acuminate), and the base acute to narrowly rounded (vs. rounded).
Additional specimens examined.
Costa Rica • San José: cantón Pérez Zeledón, distrito de Rivas, San Gerardo, Reserva Biológica Cloudbridge , 1800 m elev., 26 Apr 2023, O. Cubero, M. Rodríguez-Arias & M. Cedeño 006 ( USJ!) ; • San José: cantón Pérez Zeledón, distrito de Rivas, San Gerardo, Reserva Biológica Cloudbridge , 1800 m elev., 26 Apr 2023, O. Cubero, M. Rodríguez-Arias & M. Cedeño 007 ( USJ!) ; • San José: cantón Pérez Zeledón, distrito de Rivas, San Gerardo, Reserva Biológica Cloudbridge , 1800 m elev., 26 Apr 2023, O. Cubero, M. Rodríguez-Arias & M. Cedeño 008 ( USJ!) , Cartago: cantón de Paraíso, distrito de Orosí, Navarro , 1410 m elev., 12 Oct 2024, O. Cubero, M. Rodríguez-Arias & M. Cedeño 032 ( USJ!) .
Remarks on the spathe-subtending bracteoles in Rhodospatha .
The morphology of leaf types in Araceae is diverse, including several forms of cataphylls and reduced leaves, which have been described in detail by Ray (1987 a, 1987 b). These modified leaves are usually found subtending the peduncles, particularly in taxa forming synflorescences ( Ray 1987 a, 1987 b). However, we observed that, in several Rhodospatha species, there is a distinct bract-like structure directly subtending the spathe at the top of the peduncle. This peduncular bracteole seems to have been largely overlooked, although it was illustrated long ago by Schott, for example, in his painting of Rhodospatha wendlandii [ Schott 1864: iconography 2994, deposited in the Natural History Museum of Vienna, also available in the microfiche edition ( Nicolson 1984); cited without remark in Croat and Delannay (2024): fig. 88] and mentioned in the protologue of that species ( Schott 1864: 52) as the spathe base being ‘ auriculate’. Engler and Krause (1908: 91–96) briefly alluded to short, persistent, bluntly triangular wings at the spathe base, again in reference to the same species. In line with these morphological observations, Madison (1978) noted that, in certain species from the northern Andes, the spathe bear two orbicular “ flaps ” at the base. Nonetheless, he did not provide a detailed characterization or formal definition of this structure. However, this structure has never been documented as being as widespread (though not universal) in the genus as we have found it to be. Its exact nature remains intriguing and we cannot yet provide a definitive explanation. Could it be interpreted as part of the spathe itself and, if so, what is its function or structural significance? Might it suggest peduncle elongation during development below, rather than above, a small subtending bracteole, somewhat analogous to the internodal elongation above or below the prophylls in the sympodial shoots of Philodendron subgenus Philodendron vs. Philodendron subgenus Meconostigma (see Mayo 1991)?
We examined the inflorescence of Rhodospatha wendlandii and found that this bract-like structure has the same position (Fig. 7 A – E View Figure 7 ) as we observed in R. rubrinervis (Fig. 3 B View Figure 3 ) and R. forgetii (Fig. 6 B View Figure 6 ), always situated where the spathe begins to open and form the floral chamber. In Rhodospatha , a genus characterised by very early-deciduous and often fragile spathes, we observed that this bracteole seems to support the spathe during female anthesis, allowing the chamber to form without the base rupturing. The inflorescences of R. wendlandii and R. rubrinervis are visited by beetles of the genus Cyclocephala ( Scarabaeidae ) and these robust beetles can damage the spathe when entering the chamber. However, we detected that, when the beetles are inside, moving along the spadix, they can displace the spathe without causing it to open or break at the base, likely due to the presence of this bracteole. If the spathe were to break at the base, anthesis would end prematurely, as the spathe would rot, covering the spadix and preventing male anthesis from occurring. We hypothesise that a key structural function of this bracteole could be to act as a brake, preventing the spathe from tearing at the base when beetles enter in the female anthesis.
We have observed these structures in the following Rhodospatha species: R. antonensis Croat & O. Ortiz ( Cedeño-Fonseca et al. 2023; fig. 1: voucher O. O. Ortiz 4319 PMA), Rhodospatha forgetii (voucher O. Cubero 001 USJ), R. rubrinervis (voucher: O. Cubero 005 USJ), R. wendlandii (voucher: O. Cubero 010 USJ) and Rhodospatha sp. (voucher: E. Trujillo 8410 HUAZ).
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