Cyrtopodium × flavopunctatum J.A.N.Bat. & A.Medeiros, 1813

Batista, João A. N. & Medeiros, Alexandre Da Silva, 2022, A new putative natural hybrid of Cyrtopodium (Orchidaceae) from the south coast of Brazil, Phytotaxa 536 (3), pp. 279-286 : 280-284

Cyrtopodium × flavopunctatum J.A.N.Bat. & A.Medeiros , nothosp. nov. ( Figs. 1C–E , 2 )

Type:— BRAZIL. Santa Catarina: São Francisco do Sul , 17 November 2018, A. Medeiros 1179 (holotype, LAG)

The color of the flowers of this new natural hybrid is intermediate between C. flavum and C. gigas or C. palmifrons . It is similar to C. flavum in vegetative and floral morphology, but distinguished by the sepals and petals with brown spots, lateral lobes of lip and base of the central lobe orange or orange-spotted, very short isthmus (1–2 mm long), lip midlobe margins slightly verrucose and flowers slightly citrusy-scented.

Terrestrial herb. Roots fasciculate, numerous, ca. 5 mm wide, glabrous, white. Pseudobulbs completely above ground (epigeous), fusiform, acuminate, leafless from the second year onward, about 28 × 2.3 cm. Leaves at flowering 6 to 7 per pseudobulb, partially developed, 28–36 × 0.8–1.5 cm, coriaceous, glabrous, linear to linear-lanceolate, articulate, caducous, apex acuminate, sheath-like base; fully developed leaves not examined. Inflorescence lateral, erect, paniculate, up to 82 cm long, ca. 0.9 cm diameter, brownish-green; peduncle 53–60 cm, with 4 sheath-like bracts, appressed, 4–5.5 × 1.6–2 cm; rachis 22–29 cm long; secondary axis 3 to 5, (3.5–) 8–16 cm long; floral bracts broadly elliptical to suborbicular, 17 × 12 mm, apex apiculate, margins slightly undulate, greenish with brownish-red spots concentrated at the base and margins. Flowers up to 40, slightly citrusy-scented; ovary with pedicel ca. 12 mm long, green to greenish-brown with brownish dots. Sepals and petals outspread, concave, margins smooth, minutely apiculate; sepals ventral side greenish with brownish red spots concentrated at the base, dorsal side brownish, with the apex greenish, margins slightly undulate; dorsal sepal obovate, 16 × 9 mm; lateral sepals broadly elliptical, 15 × 10 mm; petals obovate, base slightly cuneate, apex obtuse to rotundate, 15 × 10 mm, yellow, dorsal side and base of the ventral side with brownish red spots, apex slightly reflexed; lip 3-lobed, 10 mm long, when spread 16 mm wide between the apex of the side lobes; base shortly unguiculate, ca. 1 mm long, orange; lateral lobes erect, parallel or slightly divergent to each other, dolabriform, falcate, 7–8 × 4–5 mm, orange, base yellow with orange punctuations, apex rounded, base not constricted, margins entire; callus entire, verrucose, placed between the lateral lobes, yellow orange; isthmus separating the lateral lobes from the midlobe, 1–2 mm long; midlobe reniform, 5–6 × 11–12 mm, yellow, base with orange dots, apex retuse when flattened, margins slightly verrucose, slightly undulate. Column erect, arcuate, trigonous, 5 mm long, apiculate, yellowish, base with reddish orange dots, apex light green; column foot 3.5 mm long; anther yellow, apex green; pollinia two, waxy, sulcate, yellow. Fruit not examined.

Etymology —From the Latim flavus (pale yellow) and punctatus (dotted), referring to the color of the flowers.

Distribution, Habitat and Phenology — Cyrtopodium × flavopunctatum is known only from the municipality of São Francisco do Sul, on the northern coast of the state of Santa Catarina in southern Brazil. The climate of the region, according to Köppen’s classification, is Type Cfa (wet mesothermal with hot summers), with an average annual temperature of 20.6ºC and annual precipitation of 1,857 mm ( Possamai et al. 2010). The predominant vegetation in the region is dense rainforest, restinga and mangroves. Cyrtopodium × flavopunctatum occurs in sandy soil in shrubby restinga, with predominance of shrub species of Myrtaceae ( Eugenia stigmatosa Candolle (1828: 268) and E. sulcata Spring ex Martius (1837: 85) . The new taxon is sympatric with Cyrtopodium flavum , Epidendrum fulgens Brongniart (1834: 196) , E. puniceoluteum Pinheiro & Barros (2006: 248) , and Vanilla chamissonis Klotzsch (1846: 564) . Flowering occurs in November, in early summer.

Notes — Cyrtopodium × flavopunctatum was found among a population of C. flavum , flowering at the same time, in restinga vegetation. The vegetative part is identical to C. flavum . The floral morphology is also similar to that of the C. flavum , but the new taxon differs in color and in some morphological features. While the flowers of C. flavum are predominantly yellow, without spots, the new taxon presents the sepals and petals with brown spots, and the lateral lobes and base of the central lobe orange or mottled with orange. Cyrtopodium flavum is a common species distributed along almost the entire coastline of Brazil, from the states of Rio Grande do Sul to Ceará ( Batista & Bianchetti 2020). The flowers of C. flavum show a significant variation in morphology and size ( Batista & Bianchetti 2020), but the color is well preserved and the flowers are usually completely yellow ( Fig. 1F ). Occasionally the sepals and petals are yellowish-green, or have a slightly brown dorsal surface, but never have spots or stains. The lip is always yellow, but occasionally the callus and the apex of the column foot may be slightly reddish.

The spotted flowers of the C. × flavopunctatum ( Fig. 1C–E ) are quite distinct from C. flavum ( Fig. 1F ) and resemble the color pattern of C. × intermedium Brade (1939: 44) ( Fig. 3A–C ) described as a putative hybrid between C. glutiferum Raddi (1823: 220) ( Fig. 3D–E ), a rupicolous species with yellow flowers, and C. gigas ( Figs. 1G , 3F ), an epiphytic species with spotted flowers. In this sense, the color of C. × flavopunctatum flowers resembles a mixture between the C. flavum and C. palmifrons or C. gigas , that have profusely red-spotted flowers ( Figs. 1G–H ). In addition to the differences in the color of the flowers, C. × flavopunctatum is also distinguished from C. flavum by the inconspicuous isthmus, 1–2 mm long (vs usually prominent, 3–5 mm long in C. flavum ), lip midlobe margins slightly verrucose (vs smooth) and by the slightly citrusy odor of the flowers (vs a strong soap odor).

Cyrtopodium palmifrons and C. gigas are epiphytic species distributed in the southeastern and southern parts of the Atlantic Forest domain. There are no records of these species for the locality or municipality where C. × flavopunctatum was found. However, there are records of C. palmifrons and C. gigas a little further inland in the municipalities of Luiz Alves, Blumenau and Rio dos Cedros, located 60–80 km southwest of São Francisco do Sul. Both species occur in dense rainforest, vegetation that also occurs in the São Francisco do Sul and the absence of records may be due to the small number of botanical collections in the municipality and the low frequency at which these species occur in their habitats. In a floristic inventory in the Mata do Limoeiro State Park, a 2,056-hectare conservation unit in Minas Gerais, for example, we found a single specimen of C. palmifrons (J. A. N. Batista, personal observation). Finally, C. palmifrons and C. gigas flower at the same time as C. flavum , mainly during November.

Natural hybrids in Cyrtopodium are uncommon, and so far there is only one possible natural hybrid described for the genus, C. × intermedium, supposedly originated from a cross between C. glutiferum and C. gigas , which can occur sympatrically and flower at the same time. So far, C. × intermedium is only known from two records, the type, collected in Juiz de Fora in 1937 and where it has never been found again, and a more recent record from 2008 from Rio de Janeiro. In the latter, a hybrid swarm was found, with individuals with intermediate characters, at times approaching more the floral morphology of one or the other possible parental species ( Fig. 3A–C ). Considering the spatial and temporal separation between the two records, it is possible that they correspond to independent hybridization events.

Despite the rarity of natural hybrids, there do not appear to be genetic barriers to interspecific or intergeneric crosses in Cyrtopodium . Experimental crosses with plants kept under cultivation have shown that many species are compatible, and artificial hybrids are easily formed ( Romero-González et al. 2008). There are records of artificial hybrids between species of Cyrtopodium as well as this genus with other genera of tribe Cymbidieae such as Ansellia Lindley (1844: 12) , Grammatophyllum Blume (1825: 377) and Promenaea Lindley (1843: 13) or even crosses between several genera such as Cyrtopodium , Grammatophyllum and Cymbidium Swartz (1799: 70) (Cyrtogramcymbidium) ( RHS 2021).

Cyrtopodium flavum is one of the few species of the genus for which there are pollination studies. On the coast of São Paulo, C. flavum is pollinated by two species of Centris , Centris tarsata and Centris labrosa ( Pansarin et al. 2008) , while in Florida, where the species has adapted as an invasive species, C. flavum is pollinated by Centris nitida , which in turn is also a local invasive species ( Liu & Pemberton 2010). In Brazil, there are no pollination studies for any of the epiphytic species of the genus, but in southeastern Florida, C. punctatum is pollinated by the native bee Centris errans and to a lesser degree, by the invader Centris nitida ( Pemberton & Liu 2008) . Although they are pollinated by different species, the fact that both C. flavum , from the group of terrestrial species with yellow flowers, and C. punctatum , from the group of epiphytic species with spotted flowers, are pollinated by species of Centris , reinforces the possibility that natural hybridization may occur between species of these two groups. In southern Florida, Liu & Pemberton (2010) reported that hand hybridization between the naturalized C. flavum and the native C. punctatum produced viable seeds, and expressed concern that a potential introgression from the invasive species could disrupt the gene pool of the rare native C. punctatum and further threaten its existence.

So far C. × flavopunctatum is known by a single individual. However, since terrestrial Cyrtopodium plants are common in the region where the new taxon was found and it can only be identified when flowering, it is possible that other individuals have gone unnoticed. Considering that the color pattern of C. × flavopunctatum flowers are quite distinct and does not seem to be a mere variation in the color of C. flavum , as well as the additional differences mentioned above, we propose that the specimen from São Francisco do Sul represents a natural hybrid between C. flavum and one of the epiphyte species that occur in the Atlantic Forest domain, C. palmifrons or C. gigas . In any case, additional studies with genetic data or other data source are needed to evaluate this hypothesis and, if correct, identify the other parental taxon.

Figures

FIGURE 1. Habitat and morphological characters of Cyrtopodium × flavopunctatum. A. Habitat, shrubby resting in sandy coastal plain, municipality of São Francisco do Sul, state of Santa Catarina. B. Cyrtopodium plants in the locality of the type. C. Inflorescence. D. Flower, front view E. Flower, dissected segments. Putative parental species. F. Cyrtopodium flavum (without voucher, São Francisco do Sul, Santa Catarina). G. Cyrtopodium gigas (Batista 1448—CEN, Santa Catarina). H. Cyrtopodium palmifrons (without voucher, Minas Gerais). Scale bars: C = 5 cm; D–E = 1 cm.

FIGURE 2. Cyrtopodium × flavopunctatum. A. Habit and inflorescence. B. Flower, front view. C. Perianth. D. Bract. E. Ovary and gynostemium. Drawn by Alexandre Medeiros from Medeiros 1179.

FIGURE 3. A–C. Cyrtopodium × intermedium (A, Batista & Alan 2702—BHCB; B, Batista 3030—BHCB; C, Batista & Alan 2700 – BHCB; all from Rio de Janeiro). D–E. Cyrtopodium glutiniferum (Batista & Alan 2703—BHCB, Rio de Janeiro). F. Cyrtopodium gigas (Batista & Alan 2701—BHCB, Rio de Janeiro).