Sunday, December 31, 2017

[Botany • 2017] Cypripedium × fred-mulleri • First Guatemalan Record of Natural Hybridisation between Neotropical Species of the Lady’s Slipper Orchid (Orchidaceae, Cypripedioideae)

Cypripedium × fred-mulleri  Szlach., Kolan. & Górniak

in Szlachetko, Kolanowska, Muller, Vannini, Rojek & Górniak​, 2017


The first natural hybrid in the section Irapeana of the orchid genus Cypripedium is described and illustrated based on Guatemalan material. A molecular evaluation of the discovery is provided. Specimens with intermediate flowers between C. irapeanum and C. dickinsonianum within ITS and Xdh sequences have the signal sequence of both these species. The analysis of plastid sequences indicated that the maternal line is C. irapeanum. Information about the ecology, embryology and conservation status of the novelty is given, together with a distribution map of its parental species, C. irapeanum and C. dickinsonianum. A discussion of the hybridization between Cypripedium species is presented. The potential hybrid zones between the representatives of Cypripedium section Irapeana which were estimated based on the results of ecological niche modeling analysis are located in the Maya Highlands (C. dickinsonianum and C. irapeanum) and the eastern part of Southern Sierra Madre (C. molle and C. irapeanum). Moreover, all three Cypripedium species could inhabit Cordillera Neovolcánica according to the obtained models; however, it should be noticed that this region is well-distanced from the edges of the known geographical range of C. molle.

 Figure 10: Flowers of Cypripedium. Cypripedium dickinsonianum (A), C. irapeanum (B) and Cypripedium × fred-mulleri   (C). Photos by F Muller. 

Figure 9: Habit of  Cypripedium × fred-mulleri.  Photo by F Muller. 

Figure 9: Comparison of the habit of Cypripedium dickinsonianum (A), C. irapeanum (B)
Photos by F Muller. 

Taxonomic treatment
Due to the detection of gene flow between C. dickinsonianum and C. irapeanum and mixed morphological characters of the population discovered by Mr Muller in Guatemala we decided to describe it as the first, natural hybrid in the section Irapeana under the name Cypripedium × fred-mulleri.

Cypripedium × fred-mulleri Szlach., Kolan. & Górniak, hybr. nov.

Diagnosis: Cypripedium × fred-mulleri is characterized by having flowers 5.2–7 cm across, elliptic, acute dorsal sepal, oblong-elliptic, obtuse petals, deeply saccate, obovoid-globose lip and trullate, acute staminode. It differs from C. irapeanum in its smaller flowers, deeper color (closer to C. dickinsonianum), density of windows on the lip, and form of dorsal sepal and petal apex. From C. dickinsonianum it is distinguished, inter alia, by the shape of the staminode and lip as well as by the petal form.

Type: Guatemala, Alta Verapaz. South of Cobán. 30 May 2013. F. Muller s.n. (BIGU! 309 holotype). UGDA-DLSz! - drawing of type, photos.

 Etymology: Dedicated to the discoverer of this hybrid, Fred Muller.

Distribution: Known so far to be exclusively from the Guatemalan department of Alta Verapaz. Due to the vulnerability of populations of C. irapeanum, C. dickinsonianum and C. × fred-mulleri to illicit harvesting, the exact locality is not given. The known localities of C. irapeanum are distributed from Central Mexico to Guatemala and Honduras while the currently known range of C. dickinsonianum is discontinuous, extending from eastern Chiapas (México), through the Sierra de los Cuchumatanes and the Sierra de Chamá to the central Honduran uplands (although herbarium vouchers are currently lacking Dix & Dix, 2000). Figure 8.

Ecology: The hybrid population was found on a south-oriented limestone hillside at an altitude of about 1,500 m. The plants grow in an open, seasonally dry pine-oak forest with Brahea dulcis (Kunth) Mart. (Arecaceae) and species of Agave L. (Asparagaceae). Other terrestrial orchid species occurring in this area are: Cyrtopodium punctatum (L.) Lindl., Stenorrhynchos pubens (A. Rich. & Galeotti) Schltr. and Dichromanthus cinnabarinus (La Llave & Lex.) Garay. Moreover, two species of Bletia Ruiz & Pav. have been reported from this location. The hybrid plants begin blooming in mid-May, at the beginning of the rainy season. The flowers have been observed as late as at the end of July, which is the beginning of the flowering season for both C. irapeanum and C. dickinsonianum in nearby colonies. Field observations in 2013 suggested that the population might have benefited from a recent wild fire, as a significant increase in the number of flowering specimens had previously been recorded in the season following a fire at the locality.

Dariusz L. Szlachetko, Marta Kolanowska, Fred Muller, Jay Vannini, Joanna Rojek and Marcin Górniak​. 2017.   First Guatemalan Record of Natural Hybridisation between Neotropical Species of the Lady’s Slipper Orchid (Orchidaceae, Cypripedioideae). PeerJ. 5:e4162.  DOI: 10.7717/peerj.4162


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