Liparis aphylla G.A.Romero & Garay, 1999

Damian, Alexander & Ormerod, Paul, 2016, Liparis aphylla (Malaxideae, Orchidaceae), a new leafless record from Peru, PhytoKeys 61, pp. 27-35 : 28-30

Liparis aphylla G.A.Romero & Garay Figs 1 , 2

Liparis aphylla G.A.Romero & Garay. Harvard Pap. Bot. 4(2): 483. 1999.

Type.

COLOMBIA. Boyacá: Sierra del Cocuy, 2800 m, "terrestre, entre musgos asociada con Masdevallia sp., aparentemente saprófita; tépalos blanco-verdosos, labelo púrpura lila" 20 July 1997, M. Ospina Hernández 1487 (Holotype: AMES!).

Description.

Herb, 4-10 cm tall, terrestrial. Rhizome and roots not seen. Pseudobulb subglobose, 2.5-5 × 2 mm, enveloped by a basal foliaceous green sheath 1.5 cm long. Leaves not seen. Inflorescence racemose, erect, successively (up to 6) flowered (usually two are open at a time), 7.8 cm. long; peduncle slender, 4 cm long; rachis weakly flexuous, distichous, 3.8 cm long; floral bracts lanceolate. acute, green, 5-7 × 3 mm. Flowers widely opening, resupinate, fragrance not detected, sepals and petals greenish, labellum rosy brown with a darker median stripe, column greenish suffused with rosy brown, pollinia yellow. Green, 4-6 long ovary with clavate, narrowly winged pedicel. Dorsal sepal oblong-lanceolate, obtuse, erect, 1-veined, 3-5.5 × 0.9-1.5 mm. Lateral sepals obliquely oblong-ovate, obtuse, midvein low carinate, parallell to each other under the labellum, 1-veined, 3-5 × 0.6-2 mm. Petals linear, obtuse, reflexed, 1-veined, 2.6-5 × 0.5-0.6 mm. Labellum subquadrate, distal margin serrate-denticulate, medially with a thickened glossy stripe, 3-5 × 3.5-5 mm; callus bilobed, each side with an erect, subquadrate lobe between which there is a distally thick-walled elliptical cavity. Column semiterete, thick basally but slender above, arcuate on its distal half, apex with small triangular wings on each side, 3 mm long; pollinia four in two pairs, waxy, triangular; anther cap ovoid. Capsule and seeds not seen.

Ecology and distribution.

Liparis aphylla is found in the Andes of Colombia, Ecuador and Peru, within an elevation range of 2600-3300 m. The distribution of this species, based on herbarium records, appears to be highly disjunct (Figure 3 ). However, this extreme patchiness may be an artifact of limited collecting, and we suspect that Liparis aphylla likely occurs throughout the Andean range, at climatically suitable locations ranging from the Cordillera Oriental/East Andes in Colombia to the northern Andes of Peru. Plants of Liparis aphylla grow terrestrially among loose moss in wet, cold montane cloud forest with abundant bryophytes. Flowering period: May-July.

Additional specimens examined.

ECUADOR. Prov. Azuay: East Cordillera, 4-6 km N. of Sevilla de Oro, 2745-3050 m, 16 August 1945, W.H. Camp E-4774 (AMES!, NY); PERU. Departamento Cajamarca, provincia Chota, Querocoto, entrance road to "La Granja", 6°20'6.70"S, 79°9'24.49"W; terrestrial, montane rainforest, 2600 m, 01 May 2014, A. Damian 0100 (MOL!, ADP-spirit 3033).

Conservation status.

This species is presently know only from three location worldwide; according to the IUCN Red List ( IUCN 2014) and Roque and Leon (2006) criteria, it should be listed as critically endangered (CR) B1ab(iii).

Discussion.

Liparis aphylla was described from an individual plant collected in Sierra del Cocuy, Colombia, by Romero and Garay (1997) and from another record from Azuay, Ecuador, (1977). These two specimens, along with the Peruvian specimen reported in this paper, represent the only available material of this tiny rare orchid. The overall morphology observed in these three specimens, is quite uniform except for considerable variation in labellum shape, which ranges from quadrate in the specimen Camp E-4774 to subquadrate in Ospina Hernández 1487. Moreover, the elliptic concavity of the callus of our specimen did not appear to be present in other two specimens, although it is not clear if the absence of this concavity in the latter two specimens is an artifact of preservation.

Unlike any others members of Liparis , Liparis aphylla appears as a leafless orchid with poor-developed root system. However, these two conditions need to be studied care fully. Although we were unable to see any remnant roots or rhizome on the specimens examined, Ospina Hernandez sheet (1487) includes an interesting note cited as "Plant tubers covered by fungal hyphae (...)". It is highly possible that “tubers” on this context actually refers to the pseudobulb and not to the presence of subterranean stems or shoots that resemble any kind of root-like system or rhizome as it occurs in many basal Epidendroids orchids ( Pridgeon et al. 2005, Campbell 2014). A closest analysis of the original drawing of Liparis aphylla by Romero and Garay (1997) shows sort of filamentous structures emerging beneath the pseudobulb. Since the dimensions of these formations are indistinct (0.3 × 0.1 cm), is fairly accurate to attribute those filamentouse root-like structures to the "fungal hyphae" which Ospina was referring in the first place.

Another strikingly feature on Liparis aphylla is its leaflessness. As it happens with rhizome and roots, no remnants of withered or decomposed leaves were observed neither in the field nor in available herbarium specimens. As a result of this uncommon state within Liparis , Romero & Garay decided to establish Sect. Aphylla (Romero and Garay 1997) to include this single species, which outstands essentially for its leafless habit, well-developed pseudobulb, plants of small size and muscicolous habitat. However, additional observations whether this set of characters, especially those referring to leaves and roots, are continuous or not along specimens were missing.

Leaflessness is a feature that is present in many angiosperms ( Vicent et al. 2013, Calswards et al. 2006) and Orchidaceae is not the exception. At least 235 orchid species and 43 genera are leafless, most of them found in Epidendroideae ( Freudenstein and Barrett 2010). For instance, within tribe Malaxideae , two orchids have reported being leafless: Malaxis aphylla (King & Pantl.) T.Tang & F.T.Wang and Malaxis saprophyta (King & Pantl.) T.Tang & F.T.Wang ( Vincent et al. 2013). Most of these leafless orchid display any of the following arrangements or life-forms: (1) well-developed shoot system which forms the main body (e.g. leafless Vanilla ), (2) shoot system reduced, i.e. shootless orchids, roots forming the main body of the plant (e.g. Vandeae) ( Carlsward et al. 2006), (3) roots fleshy, fasciculate, leaves basal but lacking at flowering time (e.g. Spiranthinae : Cranichideae ) ( Salazar 2003), and (4) myco-heterotrophic orchids, achlorophyllous, roots reduced or absent, rhizome fleshy, coralloid, tuberlike or cylindric (e.g. Aphyllorchis, Gastrodia) ( Rasmussen 2000). A major question rise then among others, which life-form represents better to Liparis aphylla ?. Although Romero and Garay (1997) suggested it could be referred to as a “saprophyte”, this term proved to be inaccurate ( Leake 1994). We believed Liparis aphylla could represent a partially myco-heterotrophic (holo-mycotrophic) plant, i.e. clorophyllous plant that combines autotrophy and myco-heterotrophy to obtain carbon during at least one stage of its life cycle ( Rasmussen 1995). The nonexistence of a well-developed root system, leaflessness (= myco-heterotrophic species) and retainment of chlorophyll on its basal sheath, stem and bracts seem to confirm this hypothesis. Nonetheless, it is important to keep in mind that the myco-heterotrophic status is “putative” on this species, and remains speculative until a careful physiological analysis has been carried out.

Figures

Figure 1. Liparis aphylla. A Habit B Flower C Dissected perianth D Detail of the labellum disk base E Column withouh the anter cap, ventral view F Column lateral view, and anther cap. Drawn from A. Damian 0100 (MOL!).

Figure 2. Liparis aphylla, A Habit B-C Two views of the of labellum. Arrows show the distinct elliptical concavity of the callus. Photographer: A. L. Damian.

Figure 3. Known distribution of Liparis aphylla.