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Ionopsis × atalibae (Orchidaceae, Oncidiinae), a new natural hybrid from the Brazilian Amazon

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Hybridization plays a relevant role in the evolution and diversification of flowering plants. Natural hybridization has been commonly recorded in some orchid groups. During fieldwork in a Citrus plantation in the Brazilian Amazon, plants of Ionopsis utricularioides, I. satyrioides and an unidentified taxon with intermediate morphology between both sympatric species were found. The plants with intermediate features are most likely a natural hybrid between I. utricularioides and I. satyrioides described here as I. × atalibae.
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Phytotaxa 478 (2): 268–274
https://www.mapress.com/j/pt/
Copyright © 2021 Magnolia Press Article PHYTOTAXA
ISSN 1179-3155 (print edition)
ISSN 1179-3163 (online edition)
268 Accepted by Adam Karremans: 8 Dec. 2020; published: 6 Jan. 2021
https://doi.org/10.11646/phytotaxa.478.2.8
Ionopsis × atalibae (Orchidaceae, Oncidiinae), a new natural hybrid from the
Brazilian Amazon
AMAURI HERBERT KRAHL1,3, DAYSE RAIANE PASSOS KRAHL1,4 & EMERSON RICARDO PANSARIN2,5
1 Instituto Nacional de Pesquisas da Amazônia, Programa de Pós-Graduação em Botânica, Departamento de Botânica, Av. André
Araújo, 2936, Aleixo, 69.060-001, Manaus, AM, Brazil.
2 Departamento de Biologia, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Av. Bandeirantes
3900, 14040-901, Ribeirão Preto, SP, Brazil.
3
amaurikrahl@hotmail.com; https://orcid.org/0000-0001-7862-9624
4
dayseraiane@hotmail.com; https://orcid.org/0000-0003-2899-9453
5
epansarin@ffclrp.usp.br; https://orcid.org/0000-0002-0355-8363
Abstract
Hybridization plays a relevant role in the evolution and diversification of flowering plants. Natural hybridization has been
commonly recorded in some orchid groups. During fieldwork in a Citrus plantation in the Brazilian Amazon, plants of
Ionopsis utricularioides, I. satyrioides and an unidentified taxon with intermediate morphology between both sympatric
species were found. The plants with intermediate features are most likely a natural hybrid between I. utricularioides and I.
satyrioides described here as I. × atalibae.
Keywords: Epiphytes, hybridization, Ionopsis satyrioides, Ionopsis utricularioides, sympatry
Resumo
A ocorrência de eventos de hibridização natural é de extrema importância na evolução e diversificação das Angiospermas.
A ocorrência de hibridação natural tem sido documentada em alguns grupos de orquídeas. Durante o desenvolvimento de
trabalhos de campo em uma lavoura de Citrus na Amazônia brasileira foram coletadas plantas de Ionopsis utricularioides,
I. satyrioides e uma espécie de Ionopsis com características intermediárias entre ambas as espécies simpátricas. As plantas
com características intermediárias são provavelmente um híbrido natural entre I. utricularioides e I. satyrioides descrita aqui
como I. × atalibae.
Palavraschave: Epífitas, hibridização, Ionopsis satyrioides, Ionopsis utricularioides, simpatria
Intro duction
Hybridization is the intercrossing between two or more distinct species. This process plays a relevant role in the evolution
and diversification of flowering plants. In orchids, the presence of pre-pollination barriers is a major impediment for
hybridization (van der Pijl & Dodson 1966; Vieira et al. 2017). Floral morphology, specificity of pollinators, different
flowering periods and geographic isolation are the main factors that assure the reproductive isolation between inter-
compatible species (van der Pijl & Dodson 1966, Pansarin & Amaral 2008). When such pre-pollination barriers are
strong, hybrids are rare or nonexistent (Linder 1990, Steiner et al. 1994). However, when such barriers are absent or
weak, natural hybridization occasionally occurs (e.g. van der Pijl & Dodson 1966, Borba & Semir 1998, Levin 2000,
Pansarin & Amaral 2008). Hybridization has been commonly recorded in some orchid groups, such as in Laeliinae
(Pansarin & Amaral 2008, Vieira et al. 2017).
Oncidiinae Bentham (1881: 288) is one of the largest subtribes in Orchidaceae with about 1700 species (Chase
2009). The subtribe is highly diverse regarding its pollinators and floral resources (van der Pijl & Dodson 1966,
Ackerman 1995). However, most species do not have floral resources and are pollinated by deception (Chase et al.
2009; Aguiar & Pansarin 2018). Within the large subtribe Oncidiinae, the Neotropical genus Ionopsis Kunth (1815:
A NEW IONOPSIS HYBRID FROM THE BRAZILIAN AMAZON Phytotaxa 478 (2) © 2021 Magnolia Press 269
348, t. 83) occurs from North America (Florida) to South Brazil and Paraguay, and in the Galapagos Islands (Alrich
& Higgins 2008, Govaerts et al. 2020). Within Ionopsis, seven species have been recognized: Ionopsis bevifolia
Richard & Galeotti (1845: 26), I. burchelli Reichenbach (1877: 68), I. minutiflora (Dodson & Williams 1980: 387)
Pupulin (1998: 227), I. papillosa Pupulin (1998: 227), I. satyrioides (Swartz 1788: 123) Reichenbach (1861: 683), I.
utricularioides (Swartz 1788: 122) Lindley ( 1826: t. 39) and I. zebrina Kraenzlin (1920: 435) (Govaerts et al. 2020).
In Brazil, three Ionopsis species are reported to occur, Ionopsis burchelli, I. satyrioides and I. utricularioides (Smidt
2020). Brazilian Ionopsis are distributed in the Amazon Forest, Cerrado vegetation and along the Atlantic Forest.
Furthermore, Ionopsis species have also been recorded in disturbed vegetation and reforested areas (Smidt 2020).
Species of Ionopsis are recognized by the reduced pseudobulbs covered by the lateral leaf sheaths. The inflorescence
is lateral and simple (e.g. I. satyrioides) or compound (e.g. I. utricularioides). The flowers usually are whitish or
purplish. The lateral sepals are coalescent forming a small mentum. The labellum is prominent, unguiculate, flat and
oval to obovate, with the rounded to emarginate apex. The pollinarium possesses two pollinia, a stipe and an adhesive
viscidium (Ackerman 1995). The flowers of I. uricularioides are adapted to pollination by small bees that search for
nectar on flowers (Aguiar & Pansarin 2018).
To date, no natural hybrids between species of Ionopsis have been recorded. During the developing of a fieldwork
in the Brazilian Amazon, plants of I. utricularioides, I. satyrioides and an unidentified Ionopsis with intermediate
morphology between both sympatric species were found. Since hybrids show intermediate morphological features
between I. utricularioides and I. satyrioides (e.g. Azevedo et al. 2006), our main hypothesis is the individuals with
intermediate features are hybrids. Furthermore, our previous observations show that the flowering seasons overlap. This
paper aims to investigate the occurrence of natural hybridization in the genus Ionopsis based on accurate morphological
studies on plants occurring in this Amazonian population.
Material and methods
The fieldwork was performed in a Citrus plantation in the municipality of Iranduba (3°11’33.10”S, 60°12’24.59”W),
Amazonas, Brazil, The study site is located at the km 15 of the highway AM-070, between the municipalities of Manaus
and Manacapuru. The climate is humid tropical (‘Afi’), according to Köppen’s (1948) classification. The temperature
varies from 24 to 27º C and rarely is below 18º C. The rainfall occurs throughout the year (Luizão 1995).
Ionopsis specimens were collected and vouchered according to the usual procedures (Mori et al. 1989). Vouchers
were incorporated at the INPA herbarium. Morphological terminology used in the taxonomic descriptions followed
Harris & Harris (2001). Data on the flowering phenology were gathered in the study area during the 2019 flowering
period.
Results
Ionopsis × atalibae Krahl, D.R.P.Krahl & Pansarin nothosp. nov.
Type: BRAZIL. Amazonas: Iranduba, Road AM-070, 3°11’33.10”S, 60°12’24.59”W, 0 m a.s.l., 06 July 2019, epiphyte in Citrus tree, A. H.
Krahl & F. C. L. Félix 1280 (holotype, INPA-288758). Fig. 1, 2A, 2D, 2G.
Species with intermediate morphology between I. utricularioides and I. satyrioides. The leaves of I. × atalibae are deeply curved to
supervolute-curved, and thick (vs. flat and coriaceous in I. utricularioides and acicular, thick and slightly furrowed in I. satyrioides).
The labellum of I. × atalibae is widely obovate ca. 1.1 × 1.0 cm, whitish to pale pink with dark purple oblique lines, apex deeply
emarginate, while in I. utricularioides the labellum is widely obovate, ca. 1.5 × 1.5 cm, whitish to pale pink with pale purple oblique
lines, apex deeply emarginate, and in I. satyrioides the lip is narrowly obovate, ca. 0.8 × 0.4 cm, pale purple with dark purple oblique
lines, apex slightly emarginate.
Epiphytic herb, caespitose. Pseudobulbs 0.7-1.5 × 0.2-0.6 cm, ovate or cylindrical, with a single apical leaf, covered by
the sheaths of 3-4 lateral leaves. Leaves 2.7-15.2 × 0.4-0.6 cm, curved to supervolute-curved, fleshy, dark green, apex
obtuse to acute. Inflorescence 13.2-22.5 cm, lateral, branched, with 9-36 resupinate flowers; floral bracts ca. 2 × 1 mm,
lanceolate with an acute apex. Flowers whitish to pale pink; pedicel and ovary ca. 8 mm long, cylindrical; dorsal sepal
ca. 5 × 2 mm, ovate to oblong, apex obtuse; lateral sepals ca. 6 × 1.5 mm, oblong to lanceolate, connate at the base,
KRAHL ET AL.
270 Phytotaxa 478 (2) © 2021 Magnolia Press
apex acute; petals 6 × 3 mm, oblong to lanceolate, sub-falcate, apex obtuse; labellum ca. 11 × 10 mm, widely obovate,
whitish to pale pink, with dark purple oblique lines and a yellow callus at the base, apex deeply emarginate; callus ca.
3 mm long. Column ca. 2 mm long, clavate, clinandrium with entire margins; pollinia 2, yellow. Fruit not seen.
FIGURE 1. Ionopsis × atalibae. A. Habit. B. Flowers. C. Perianth parts. D. Labellar callus. E. Column in side view. F. Column in ventral
view. G. Dorsal view of the anther cap. H. Ventral view of the anther cap. I. Pollinarium. Photographed by A. H. Krahl.
A NEW IONOPSIS HYBRID FROM THE BRAZILIAN AMAZON Phytotaxa 478 (2) © 2021 Magnolia Press 271
FIGURE 2. Comparison between I. × atalibae (A–C), I. satyrioides (D–F) and I. utricularioides (G–I).
KRAHL ET AL.
272 Phytotaxa 478 (2) © 2021 Magnolia Press
FIGURE 3. Ionopsis satyrioides (right) and I. utricularioides (left) occurring in sympatry in the population studied. Note both species
growing on the same phorophyte.
Etymology:—the specific epithet honors Antônio Ataliba Félix, father of Francisco Clóvis Lima Félix, an orchid
collector from Manaus (Amazonas, Brazil) who found the studied population.
Additional specimens examined:—Paratype: BRAZIL. Amazonas: Iranduba, Road AM-070, 3°11’33.10”S,
60°12’24.59”W, 0 m a.s.l., 06 July 2019,epiphyte on Citrus tree, A. H. Krahl & F. C. L. Félix 1281 (LBMBP).
Specimens of
I. satyrioides examined:—BRAZIL. Amazonas: Iranduba, Road AM-070, 3°11’33.10”S,
60°12’24.59”W, 0 m a.s.l., 06 July 2019, epiphyte in Citrus tree, A. H. Krahl & F. C. L. Félix 1276 (LBMBP); ibid.,
A. H. Krahl & F. C. L. Félix 1277 (LBMBP); ibid., A. H. Krahl & F. C. L. Félix 1278 (LBMBP); ibid., A. H. Krahl &
F. C. L. Félix 1279 (LBMBP); ibid., 28 July 2019, A. H. Krahl 1294 (INPA 288760); ibid., A. H. Krahl 1295 (INPA
288759).
Specimens of
I. utricularioides examined:—BRAZIL. Amazonas: Iranduba, Road AM-070, 3°11’33.10”S,
60°12’24.59”W, 0 m a.s.l., 06 July 2019, epiphyte in Citrus tree, A. H. Krahl & F. C. L. Félix 1272 (LBMBP); ibid.,
A. H. Krahl & F. C. L. Félix 1273 (LBMBP); ibid., A. H. Krahl & F. C. L. Félix 1274 (LBMBP); ibid., A. H. Krahl &
F. C. L. Félix 1275 (LBMBP); ibid., 28 July 2019, A. H. Krahl 1292 (INPA 288761); ibid., A. H. Krahl 1293 (INPA
288762).
Distribution and habitat:—The new hybrid was collected in the municipality of Iranduba in the km 15 of the
Road AM-070, between the municipality of Manaus and Manacapuru.
Phenology:—The flowering period of I. × atalibae occurs from July to August. Ionopsis utricularioides flowers
from May to October, while I. satyrioides flowers from June to December. The flowering period of the sympatric
parental species overlaps in the study area.
Morphological affinities:—The new hybrid possesses intermediate morphology between both parental species.
The leaf disposition and shape are reminiscent of those of I. utricularioides. The leaves are deeply curved to supervolute-
curved, and thick. The labellum is widely obovate ca. 11 × 10 mm, whitish to pale pink with dark purple oblique lines,
apex deeply emarginate (Table 1). As in I. utricularioides, the inflorescence of the hybrid is branched. However, it
produces less flowers than I. utricularioides but more than I. satyrioides (Table 1). The size and shape of the hybrid
flowers is intermediate between I. utricularioides and I. satyrioides (Table 1, Fig. 2).
A NEW IONOPSIS HYBRID FROM THE BRAZILIAN AMAZON Phytotaxa 478 (2) © 2021 Magnolia Press 273
TABLE 1. Comparison among I. × atalibae, I. satyrioides and I. utricularioides.
Species Feature I. × atalibae I. satyrioides I. utricularioides
Pseudobulb Ovoid to cylindrical, 7–15 × 2–6
mm Cylindrical, 7–11 × 4–5 mm Elliptic to ovoid, 6–17 × 1–5 mm
Leaves
Curved to supervolute-curved in
cross-section, fleshy, 2.7–15.2 ×
0.4–0.6 cm, 3–5/pseudobulb
Cylindrical, slightly sulcate in cross-
section, fleshy, 8.9–11.1 × 0.4–0.5 cm,
2–3/pseudobulb
Oblong, flat in cross-section,
coriaceous, 5.2–17.4 × 0.8–1.7 cm,
3–5/pseudobulb
Inflorescence Branched, 13.2–22.5 cm, 9–36-
flowers
Simple/branched, 10.1–16.9 cm, 2–4-
flowers
Branched, 25.6–64.5 cm, 17–139-
flowers
Dorsal sepals Ovate to oblong, ca. 5 × 2 mm Oblong to lanceolate, ca. 0.6 × 2.5 mm Ovate, ca. 7 × 3 mm
Petals Oblong to lanceolate, ca. 6 × 3 mm,
apex obtuse Oblong, ca. 7 × 3 mm, apex acute Elliptic, ca. 8 × 4 mm, apex obtuse
Labellum
Widely obovate, ca. 11 × 10 mm,
whitish to pale pink with dark
purple oblique lines, apex deeply
emarginate
Narrowly obovate, ca. 8 × 4 mm, pale
purple with dark purple oblique lines,
apex slightly emarginate
Widely obovate, ca. 15 × 15 mm,
whitish to pale pink with pale
purple oblique lines, apex deeply
emarginate
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... Hybridization is seen as a common process in Orchidaceae and is known to occur in many genera across the family (e.g. Azevedo et al. 2006, Pansarin & Amaral 2008, Pinheiro et al. 2010, Hu et al. 2011, Marques et al. 2014, Cetzal-Ix et al. 2018, Krahl et al. 2020, Krahl et al. 2021a. In orchids, the existence of pre-pollination barriers (e.g. ...
... geographic barriers, different volatile compounds, different floral morphologies, among others) is the main factor preventing from the occurrence of hybridization (van der Pijl & Dodson 1966) and, when these barriers are weak, hybridization occasionally occurs naturally (e.g. van der Pijl & Dodson 1966, Borba & Semir 1998, Levin 2000, Pansarin & Amaral 2008, Cetzal-Ix et al. 2018, Krahl et al. 2021a. This seems to be a common occurrence in genus Catasetum Richard ex Kunth (1822: 330), with a total of 29 natural hybrids described so far (Govaerts et al. 2021). ...
... Considering that hybrids typically present intermediate morphological features between their parents (e.g. Azevedo et al. 2006, Krahl et al. 2021a, we here propose Catasetum × sheyllae as a new nothospecies, putatively resulting from the natural and occasional crossing of these two taxa. ...
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