Laelia × meavei Cetzal & E.A. Pérez-García, 2020

Cetzal-Ix, William, Carnevali, Germán, Jiménez-Machorro, Rolando & Pérez-García, Eduardo A., 2020, Laelia × meavei: A new natural hybrid between L. dawsonii fo. dawsonii and L. rubescens fo. peduncularis (Orchidaceae: Laeliinae) from Oaxaca, Mexico, Phytotaxa 446 (2), pp. 81-94 : 83-91

Laelia × meavei Cetzal & E.A. Pérez-García , nothosp. nov. ( Fig. 1 , 2 ).

Herba epiphytica, L. dawsonii fo. dawsonii similis sed statura minore, floribus illis L. rubescens fo. penducularis similaribus sed grandioribus et magis diuturnis, inflorescentia caulis tereti. Ab Oaxaca endemica.

Type:— MEXICO. Oaxaca: Sola de Vega City (16º30´54” N, 96º58´35” W), plants cultivated in this city in the Distrito de Sola de Vega. 417 m, J. J. Pérez-Meza sub. G. Carnevali 7953 pressed on November 2013 (holotype: CICY; isotype: AMES) .

Epiphytic herb. Roots 1–2 mm thick, rounded, slender, flexuous, white to greenish. Rhizome short, creeping. Reproductive (mature) pseudobulbs erect, 5.6–6.27 × 3.0– 3.65 cm, 1.8–2.19 cm thick, striate, elliptic in outline, apically 1(2)-“… leaved, elliptic-rhomboid in transversal section, formed mainly by a single internode, stem rhizomatous portion 1.9–2.9 × 0.7 cm. Leaves 1–2, 8.0–15 × 2.9–5.6 cm, 0.15 cm thick, coriaceous, sessile, elliptic to elliptic-oblong, acute, sometimes with a mucron. Inflorescence terminal, erect, 43–62 cm long; peduncle terete, greenpurplish, 2 mm thick, bearing 16 bracts subequal to internodes, the bracts tubular, acute, progressively shorter, apically carinate and conduplicate, subchartaceous, whitish at anthesis, 3.2–4.0 cm long, with 2 broader bracts at the base of the peduncle, imbricate, 1–2 cm long. Raceme compact, subcorymbose, with 2–3 successive flowers, rachis 2 cm long, floral bracts 2.1–3.0 × 4 cm. Ovary with pedicel, 4.0– 4.2 cm long, ca. 2–4 mm thick apically, 1–2 mm thick at base. Flowers resupinate, lasting several days on the plant, with sepals and petals pale-bright purple; labellum similar, the disc with a large maroon-purplish blotch, purple outline, isthmus whitish with yellow, anther pink. Sepals spreading, slightly convex, recurved, smooth; dorsal sepal 4.5–4.6 × 1.2–1.3 cm, oblanceolate to narrowly elliptic, subacute to very obtusely rounded; lateral sepals 4.4–4.5 × 1.1–1.2 cm, oblique to falcate, lanceolate to linear-elliptic, subacute to obtuse. Petals 4.2–4.3 × 1.9–2.0 cm, spreading, slightly convex, recurved, obliquely elliptic to rhombic, widely obtuse to rounded, base cuneate. Labellum 3-lobed, 3.2–3.4 cm long from the base to the apex of the central lobe, 2.9–3.0 cm wide across the apices of the lateral lobes; central lobe 1.4–1.5 × 1.7–1.8 cm, whitish pink with whitish yellow in its central portion, semiovate to subquadrate; lateral lobes 2.2–2.3 × 1.2–1.3 cm, enclosing the column, cuneate, sometimes broader and with divergent apices, oblique, margins undulate; callus made up of 3-longitudinal keels, from near the base of the labellum to the base of the midlobe. Column 1.4–1.5 cm long, 3.8–4.0 mm wide at base, 4–5 mm wide apically, semiclavate, ventrally concave; with small, triangular rounded wings near the base, the margins of the apical part prominent, but no forming distinct wings, the clinandrium with two lateral teeth and a erect central tooth. Anther quadrate, bilobed in profile, 8 celled, white suffused with lilac, ca. 2.2 × 2.4 mm. Pollinarium 2 × 2 mm, made up of 8 pale yellow pollinia, strongly compressed laterally, the lower pollinia obliquely flabellate-quadrate, upper pollinia elliptic quadrate, with granulose caudicles, strongly united in 2 pairs, each pair rhombic. Rostellum a transversely oblong, rounded, inclined backwards, convex blade, with a well-defined viscidium, wich is a massive area with glue on the abaxial part. Stigmatic cavity accupying up to 1/3 third of the column length, obtriangular, concave, shiny, hyaline-pinkish, lateral lobes inconspicuous. Capsule not seen.

Eponymy:—This taxon is dedicated to Jorge A. Meave, a renowned botanist, plant ecologist, and former President of the Botanical Society of Mexico.

Discussion:—Notwithstanding the high frequency of natural hybridization in several orchid groups ( Nielsen 2000; Cozzolino et al. 2005; Azevedo e t al. 2006), the number of species of hybrid origin is awaiting proper assessment, and the number of hybrids capable of forming stable populations is unknown. One such generalized hybrid in Laeliinae is Guarianthe × guatemalensis ( Moore, 1861: 61) Higgins (2004: 39) [= G. skinnerii ( Bateman, 1837 t. 13) Dressler & Higgins (2003: 38) with G. aurantiaca ( Bateman, 1838: Misc. 8) Dressler & Higgins (2003: 38)] from Chiapas and Guatemala. Similarly, there are some cases of generalized introgression, rendering the distinction between pure species and hybrids very difficult, as exemplified by Encyclia × nizandensis Pérez-García & Hágsater (2003: 564) and Encyclia rodolfoi Archila, Chirón & Véliz (2013: 6) , from the Nizanda region, Oaxaca (see Carnevali et al. 2018), or several species of this genus from the Greater Antilles ( Pérez-García & Hágsater 2012).

The possibility of natural hybridizations taking place in Epidendroideae and their potential effects on the group’s diversification are topics of increasing relevance ( Romero & Carnevali 1989; Halbinger & Soto-Arenas 1997; Pérez-García & Hágsater 2012). Natural hybrid occurrence has been recorded in almost every commercially important orchid group such as Cattleya , Encyclia Hooker (1828: 55 , pl. 2831), Epidendrum Linnaeus (1763: 1347) , Guarianthe Dressler & Higgins (2003: 37) , Oncidium Swartz (1800: 239) , Prosthechea Knowles & Westcott (1838: 111–112) , and Rhynchostele Reichenbach (1852: 770) ( Hágsater et al. 2005; Pérez-García & Hágsater 2012; Mó et al. 2014), including the genus Laelia ( Solano et al. 2019) . Among the natural hybrids recognized within this latter genus is L. × oaxacana Salazar & Jiménez (in Salazar et al. 2014: 167), which resulted from the introgression of L. halbingeriana Salazar & Soto-Arenas (in Salazar et al. 2014: 162) recognized until recently as L. superbiens from Oaxaca, ( Soto-Arenas 2003; Salazar et al. 2006) with L. anceps ( Halbinger & Soto-Arenas 1997) . Also, the alleged natural hybrid of L. dawsonii with L. albida , known as L. × finckeniana ( O’brien (1893: 194) was described probably from wild plants. More recently, the natural hybrid between L. furfuracea and L. albida was described from plants collected in the field near the city of Tlaxiaco, Oaxaca ( Solano et al. 2019), and was named as L. × tlaxiacoensis Solano & Cruz García (in Solano et al. 2019: 235).

Laelia gouldiana , an endemic species from the Barranca de Metztitlán, Hidalgo state, has been proposed to be a species of hybrid origin, which supposedly resulted from the crossing of L. autumnalis with L. anceps (L. Autoceps). However, the very different shapes of both flowers and vegetative portions between L. × Autoceps and L. gouldiana , and the absence of L. autumnalis in the Barranca de Metztitlán, cast serious doubts on the hybrid origin of L. gouldiana ( Halbinger & Soto-Arenas 1997) . Recent molecular evidence (Peraza et al. 2016), retrieving conflicting topologies in plastid-based versus nuclear-based phylogenies, strongly suggest that L. gouldiana is indeed of hybrid origin; however, the exact parentage can not be assessed with certainty at this time. In addition to intrageneric hybrids, an intergeneric hybrid of Laelia was found derived from L. speciosa and Prosthechea karwinskii ( Martius, 1830: t.10) Shaw (2011: 38). This hybrid is currently under study for its formal description.

Plants of Laelia × meavei are, in general, somewhat smaller that the typical L. dawsonii fo. dawsonii ( Fig. 1 , 3 , 4 , Table 1). The peduncle of the inflorescence is terete as in L. rubescens rather than dorsally flattened (elliptical in cross-section) as in L. dawsonii ( Table 1). Flowers of L. × meavei are bigger and longer-lasting than those of L. rubescens fo. peduncularis ( Figs. 1 , 5 , Table 1). Typically, the flowers of L. × meavei last a couple of weeks while those of L. rubescens last about a week. The overall shape and color of L. × meavei are more similar to L. rubescens fo. peduncularis and L. rubescens fo. rubescens , namely the flowers bear a yellow callus with three straight, nonprominent keels (unlike L. dawsonii ), and they display the typical dark magenta spot in the label’s throat found in the Laelia rubescens complex ( Figs. 1 , 5 , 6 ).

Laelia × meavei is known from plants cultivated in Sola de Vega, Oaxaca state, these being most likely plants collected in the Sierra Madre del Sur, a region where the occurrence of the two putative parents of this taxon has been recorded ( Fig. 2 ). A further specimen is known that was collected by G.E. Pollard (flower mounted on cardboard) in a locality to the south of Sola de Vega. During a visit to this village, some divisions of a cultivated plant were purchased. One of these was cultivated by Miguel Ángel Soto-Arenas, and when it flowered, the Asociación Mexicana de Orquideología awarded this plant with a silver medal, as it was assumed at that time that this plant represented an exceptional form of L. rubescens fo. peduncularis ( Fig. 5 ). This cultivar was named “Ocuilan”, because the owner of the plant had an orchid collection at that location. Eventually, it was assumed that the “Ocuilan” cultivar was of hybrid origin though probably not primary, resulting of crosses and backcrosses of L. dawsonii fo. dawsonii ( Fig. 4 ) with L. rubescens fo. peduncularis ( Fig. 5 ) ( Halbinger & Soto-Arenas 1997). As an alternative to the hybrid origin hypothesis, the possibility was suggested that this plant was actually a polyploid individual of Laelia rubescens ( Halbinger & Soto-Arenas 1997) .

Laelia rubescens ranges in elevation from sea level to 1250 m, whereas L. dawsonii fo. dawsonii ranges from 1500 to 2170 m. Laelia rubescens is typically a lowland species, but in this portion of the Sierra Madre del Sur there are also populations of this species at higher elevations. Actually, a complex of distinct taxa is likely to reside within L. rubescens and populations from the Sierra Madre del Sur region may be eventually treated as a different species. In fact, they are currently considered as a geographical form, namely L. rubescens fo. peduncularis , which is characterized by a glabrous throat, as opposed to the typically densely pubescent throat of most populations of the L. rubescens complex (e.g., L. rubescens fo. rubescens ). Thus, it is not unlikely that in the future this taxon will be recognized as a different species, in agreement with the recognition of L. aurea ( Navarro et al. 1990) , a species very close to L. rubescens from the Sinaloa, Durango, and Nayarit states. Even in a well-known genus, ornamentally and culturally important, such as Laelia , novelties have been reported in recent years, such as the case of L. halbingeriana ( Salazar et al. 2014) , a taxon closely related to L. superbiens . Another example is Laelia mottae (Archila et al. 2014) which covers the L. anceps -like populations from Guatemala and Honduras.

Taxonomic commentary:—As discussed above, the name Laelia × Maronii is inadequate for the alleged hybrid between L. rubescens fo. peduncularis with L. dawsonii fo. dawsonii . This is why we propose the name L. × meavei for the nothospecies described here. It is most likely that in creating Laelia × Maronii, the parents employed were Laelia anceps and a typical lowland form of L. rubescens . Thus, the use of the name L. × meavei will be restricted to the cross of L. dawsonii and L. rubescens , and will help clarify eventual typification and nomenclatural problems.

In addition to taxonomic issues, other reasons prompt us to treat Laelia × meavei as a different entity as L. × Maronii. Laelia × Maronii has never been found growing in the wild, which may be simply a result of its parents not being sympatric in the field. Also, there is a significant gap between the flowering periods of the putative parental entities, as L. rubescens tends to flower later in the year (from late November to December), compared to the flowering peak of L. anceps , which occurs between late October and early November. Conversely, it appears that both the elevational and reproductive ranges of L. dawsonii fo. dawsonii and L. rubescens fo. peduncularis are more similar, particularly in the Sierra Madre del Sur region, where L. × meavei is native from. The highest elevation record for L. rubescens fo. peduncularis (1250 m) comes from the Juquila region, Oaxaca, and this elevation does not differ substantially from the lowest elevation limit known for L. dawsonii fo. dawsonii .

Paratype:— Mexico. Oaxaca: Distrito de Sola de Vega. Plant cultivated in Sola de Vega, purchased on July 17, 1991. Common name: Huichilas. Collected with M.A. Soto-Arenas and M. Hernández Apolinar, E.A. Pérez-García 302 (AMO).

Additional specimens examined:— Laelia dawsonii fo. dawsonii : Oaxaca: I. Trujillo Olazo 1053 (MEXU), E. Hunt Oax-517 (MEXU). Laelia dawsonii fo. chilapensis: Guerrero: E. Hágsater 3680 (MEXU), O. Nagel & E. Ostlund 2679 (MEXU), H. Kruse 19731101-264 (MEXU). Laelia rubescens fo. peduncularis : Oaxaca: M. Sousa 6323 (MEXU), M. Sousa 8379 (MEXU), E. Martínez S. 32978 (MEXU), M. Elorsa 3966 (MEXU). Guerrero: A. Reyna 160 (MEXU), H. Kruse 160 (MEXU), O. Nagel 5119 (MEXU), J. Calónico Soto 19229 (MEXU). Laelia rubescens fo. rubescens : Mexico: Campeche: D. Ocaña-Nava 314 (MEXU), E. Cabrera 15305 (MEXU), E. Martínez 29946-A (MEXU). Chiapas: D.F. Breedlove 29683 (MEXU). Guerrero: J.C. Soto Nuñez 7145 (MEXU). Michoacán: B. Guerrero 359 (MEXU). Jalisco: R. McVaugh 24445 (MEXU). Nayarit: C. Feddma 2609 (MEXU). Puebla: A. Torralba 3217 (MEXU). Yucatán: W. Cetzal 376 (CICY). El Salvador: J. Linares 3563 (MEXU).

Figures

FIGURE 1. Laelia × meavei Cetzal & E.A. Pérez-García. A. Flower. B. Labellum, front view. C. Labellum, back view. D. Sepals and petals, front view. E. Ovary-pedicel, labellum and column, front view. F. Ovary-pedicel, labellum and column, back view. G. Ovarypedicel, and column, front view. H. Column, front view. I. Column, back view. J. Anther cap and pollinarium (based on J.J. Pérez-Meza sub. G. Carnevali 7953, CICY).

FIGURE 2. Distributional records of Laelia × meavei, putative parents and related species.

FIGURE 3. Plants of the natural hybrid and putative parents. A. Laelia dawsonii. B. Laelia × meavei. C. Laelia rubescens fo. peduncularis

FIGURE 4. Laelia dawsonii fo. dawsonii. A. Flower. B. Labellum, front view. C. Labellum, back view. D. Sepals and petals, front view. E. Ovary-pedicel, labellum and column, front view.F. Ovary-pedicel, labellum and column, back view. G. Column, front view. H. Column, lateral view. I. Anther cap and pollinarium (based on E.A. Pérez-García 308, AMO).

FIGURE 5. Laelia rubescens fo. penducularis.A. Plant with flowers in habitat (Oaxaca, Mexico), B. Flowers, close up (Puerto Escondido, Oaxaca, Mexico) (based on G. Carnevali s.n., CICY).

FIGURE 6. Laelia rubescens fo. rubescens. A. Flower. B. Labellum, front view. C. Labellum, back view. D. Sepals and petals, front view. E. Ovary-pedicel, labellum and column, front view. F. Ovary-pedicel, labellum and column, back view. G. Ovary-pedicel, and column, front view. H. Column, front view. I. Column, back view (based on W. Cetzal 376, CICY).