Cohniella, Pfitzer, 1889
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https://doi.org/ 10.11646/phytotaxa.144.2.2 |
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https://treatment.plazi.org/id/512487E3-8A1B-7271-0FEC-F8A6FF64FEC7 |
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Felipe |
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Cohniella |
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Cohniella View in CoL × francoi Cetzal & Carnevali , nothosp. nov. ( Figs. 1–5 View FIGURE 1 View FIGURE 2 View FIGURE 3 View FIGURE 4 View FIGURE 5 )
Cohniella × francoi is a nothospecies intermediate between C. ascendens and C. brachyphylla . It resembles the former in the semi-pendulous habit, the general morphology of the callus, the linear-oblong column wings, and the obovate stigmatic cavity. It is similar to C. brachyphylla in the oblong to subquadrate, spreading lateral lobes of the labellum and in the rectangular disc of the labellum with a conical lateral extension on the margins. It is distinguished from both parental taxa by the brown callus with white teeth as well as the combination of the Cohniella ascendens type callus with a rectangular disc bearing conical lateral extensions on the margins.
Type: –– COSTA RICA. Guanacaste: near Santa Rosa National Park, 19 February 2009, Pupulin s.n. sub Carnevali 7257 (holotype, CICY!; isotypes, AMES!, JBL!) .
Epiphytic, semipendulous herbs. Pseudobulbs 9–12 × 9–12 mm, subspherical to broadly ovoid, apically 1- leaved, red-purple tinged, totally enclosed by 3 imbricate sheaths. Leaves (13.6–)17.8–52.0 × 0.5–0.7 cm, terete, thickly fleshy-coriaceous, dark green, usually purple spotted. Inflorescences solitary from the base of the pseudobulbs, 9.7–21.0 cm long, a 5–10-flowered raceme; peduncle 5 cm long, and rachis 1.5 cm long, both dark green, purple tinged. Flowers 18–19 mm diameter, resupinate, with widely spreading perianth parts and the petals and sepals somewhat reflexed; ovary with pedicel 10–11 mm long, of which 2.5–3.0 mm correspond to the ovary, this 1 mm thick. Sepals basally clawed, spreading or somewhat reflexed, dorsal sepal 6.0–7.0 × 4.0– 4.3 mm, oblanceolate, apically obtuse and minutely apiculate, concave in the upper half, the claw 1.0–1.2 × 1.1–1.2 mm. Lateral sepals fused at the very base, then free, similar to dorsal, 7.0–7.5 × 3.5– 3.8 mm. Petals 6.5–7.0 × 3.5–4.0 mm, oblong to oblanceolate, somewhat oblique, the apex rounded, somewhat reflexed in natural position. Labellum deeply 3-lobed, 10–11 mm long from the base to the apex of the central lobe, 11–12 mm wide across the apices of the lateral lobes, the lateral lobes in the same plane as the central lobe and + /- perpendicular to it; central lobe 7.0–8.0 × 12.0– 12.5 mm, spathulate to transversely oblate or circular in outline, apically rounded to subquadrate, basally produced into a short isthmus, 2.0–3.0 × 1.0– 1.5 mm; lateral lobes 4.0–4.5 × 3.0– 3.5 mm, patent, somewhat reflexed in natural position, oblong to subquadrate, apically truncate-rounded, the upper and lower margins of the lateral lobes flat to rounded; disc (the basalmost section of the labellum that carries the callus) 4.0–4.5 × 3.0– 3.5 mm, rectangular, bearing a well-developed callus, 4.0–4.2 × 2.5–2.6 mm, brown, consisting of a large, elevated, + /- flat, hemicircular platform, 2 × 2 mm, proximally with two small, lateral, white, divergent teeth, that are obconical and point upward, 1.0–1.5 × 0.3–0.5 mm; distally with two lateral teeth, broadly rectangular to conical, these 1.8–2.0 × 0.8–1.0 mm; the central tooth or keel laterally compressed, ca. 2 mm long; the basal portion of the callus with conical lateral extensions. Column 3.0–3.2 × 1.2–1.5 mm, the ventral face in the same plane as the labellum lobes, oblong, tabula infrastigmatica longitudinally channeled, stigmatic cavity rounded, 1 × 1 mm; column wings small, 2 × 1 mm, linear-oblong. Anther cap 1.8 × 1.5 mm, apical, operculate, ellipsoid. Pollinarium 1 mm long, tegula spathulate, 0.5 × 0.3 mm, viscidium disciform, pollinia 0.5–0.8 mm long, yellow. Capsule 38.5 × 7.0 mm, elliptical, pale green with reddish spots.
Anatomical description ( Fig. 4 View FIGURE 4 ):–– Dermic tissue system. Cuticle: Smooth ( Fig. 4E View FIGURE 4 ) Epidermis: monostratified, cells with external periclinal walls thick and convex. In frontal view, the cells are arranged in rows, are isodiametric to slightly elongated, hexagonal, with thick, straight anticlinal walls, with angulose tapering end walls. Bulliform cells: absent. Stomata: tetracytic, guard cells without papillae, striations absent. Fundamental tissue system. Mesophyll: leaf unifacial, parenchyma homogeneous, cells of variable sizes, arrangement and morphology, with some cells bearing reticulate thickenings in the walls ( Fig. 4F View FIGURE 4 ); numerous bundles of extravascular fibers arranged in two series ( Fig. 4D–E View FIGURE 4 ), the outermost one layer of cells from the epidermis, the other 3–7 layers of cells deeper. Hypodermis: absent. Cellular inclusions: druses in some mesophyll cells toward 2–6 cell apart from the epidermis. Vascular tissue system: comprised by closed, collateral vascular bundles ( Fig. 4B–C View FIGURE 4 ), arranged in two central, concentric series ( Fig. 4A View FIGURE 4 ), made up of bundles of a larger size and many of smaller dimensions which are scattered in the mesophyll.
Distribution and ecology:–– Cohniella × francoi is only known from the vicinity of the Santa Rosa National Park in Guanacaste province, Costa Rica. This hybrid grows in tropical dry forest ( Holdridge 1967) where the distribution ranges of its putative parents, C. ascendens and C. brachyphylla , overlap ( Fig. 2 View FIGURE 2 ). The Santa Rosa National Park and surrounding areas are located in the Santa Rosa Plateau at 300 m of elevation, between the Pacific Coast and the Guanacaste Cordillera ( Heinrich & Hurka 2004); in this area both putative parents have been recorded; the C. brachyphylla parent was misidentified by these authors as Oncidium cebolleta ( Jacquin 1760: 30) Swartz (1800: 240) and the C. ascendens parent as O. ascendens Lindley (1842: 4) . Vouchers for these two species from the general Guanacaste area are cited in Cetzal-Ix & Carnevali (2010).
In most localities along their distributional range, both parental taxa are allopatric ( Fig. 2 View FIGURE 2 , map scale is too large in some areas to clearly show this). However, in a few known localities both species appear to be parapatric, i.e. occurring in the same general area but growing in different vegetation types; Cohniella ascendens always found growing in the more humid, shadier places. Thus, the two taxa can grow within flying distance of a potential common pollinator. The occurrence of this natural hybrid between C. ascendens and C. brachyphylla suggests that, where the existence of vegetation mosaics allow for the habitats of both parental taxa to coexist within pollinator flying distance, gene exchange between these clearly different taxa may occur. We know little about the pollinators of these two taxa. We have observed oil-gathering Centris bees visiting C. brachyphylla both in the field as in cultivation (where the visits result in the successful production of capsules), whereas have never seen any pollinator on C. ascendens . There is a report of Trigona nigra Cresson as a pollinator of C. ascendens ( Parra-Tabla et al. 2000) but the reported locality (Dzilam de Bravo in northern Yucatan State, México) makes it highly unlikely that they were actually studying this species (most likely it was C. yucatanensis ). Since there are no plant vouchers reported in the Parra-Tabla et al. (2000) study, we have to disregard the report at this time.
Eponymy:— Named after Franco Pupulin , Professor at the University of Costa Rica and researcher at the Lankester Botanical Garden, who collected the type specimen .
Morphological analysis:—The morphology of this specimen from Costa Rica is intermediate between C. ascendens and C. brachyphylla . The semipendulous habit, the callus type, the linear-oblong column wings, and the obovate stigmatic cavity are similar to those of C. ascendens . On the other hand, the erect, oblong to subquadrate lateral lobes of the labellum as well as the rectangular disc of the labellum with conical lateral extension on the margins are similar to those of C. brachyphylla . Comparisons between the putative hybrid and its putative parental species are featured in Table 2 and Figure 3 View FIGURE 3 .
Cohniella × francoi is further distinguished from C. ascendens and C. brachyphylla by the brown callus with white teeth whereas the combination of the Cohniella ascendens type callus with a rectangular disc bearing conical lateral extensions on the margins is unique to this nothospecies ( Fig. 5 View FIGURE 5 ).
Anatomical analysis:— Cohniella × francoi has anatomical features intermediate between the putative parents ( Table 3). It is similar C. ascendens by the smooth cuticle, convex external periclinal walls of the epidermal cells, the absence of striations in the stomatal guard cellls, the absence of starch in parenchyma cells of mature plants, and the presence of druses in parenchyma cells; it is similar to C. brachyphylla in the hexagonal epidermal cell shape. This combination of anatomical features renders this nothospecies most similar to C. ascendens . Otherwise, the putative hybrid is characterized anatomically by tetracytic stomata, reticulate wall thickening walls of the mesophyll cells, and the vascular bundles arranged in two central arches. Cohniella species with smooth cuticle are usually found growing under more shady and humid conditions than those with a papillose cuticle (Cetzal-Ix 2012b). This nothospecies also has two concentric rings of vascular bundles in the mesophyll, a character found only in species of the C. ascendens complex (albeit absent from C. ascendens itself), a group of species restricted to humid, shady environments (Cetzal-Ix 2012b).
No known copyright restrictions apply. See Agosti, D., Egloff, W., 2009. Taxonomic information exchange and copyright: the Plazi approach. BMC Research Notes 2009, 2:53 for further explanation.
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