Dichaea auriculata Pupulin & Karremans, 2020

Pupulin, F. & Karremans, A. P., 2020, A new and unusual species of Dichaea (Orchidaceae: Zygopetalinae) from Costa Rica, Blumea 65 (1), pp. 61-64 : 61-63

publication ID

https://doi.org/10.3767/blumea.2020.65.01.06

persistent identifier

https://treatment.plazi.org/id/D15D8792-FFC2-0E7D-FCE6-0DD7FB8CE3D0

treatment provided by

Felipe

scientific name

Dichaea auriculata Pupulin & Karremans
status

sp. nov.

Dichaea auriculata Pupulin & Karremans View in CoL , sp. nov. — Fig. 1 View Fig , 2 View Fig ; Map 1 View Map 1

Species sectionis Pseudodichaeae, ab omnibus species Dichaeae Lindl. auriculis magis rotundatis et carina alta in basi labelli facile distinguenda; inter species foliis articulatis ovarioque glabro munitas (genus Dichaeopsem sensu Pfitzer vel coetum Dichaeae panamensis informaliter dictum), Dichaea gracillima C.Schweinf. in habito formaque et dimensione floris similis sed floribus plerumque autogamis labello distincte trilobo lobulis basalibus rotundatis, carina alta in isthmo labelli, ligula columnae bipartita recedit. — Type: A.P. Karremans 7333, I. Chinchilla, M. Díaz & G. Rojas-Alvarado (holo JBL), Costa Rica, Cartago,Turrialba,Tayutic,Jicotea, N9°47'25.74" W83°32'29.45", 1014 m, epiphytic in secondary mature vegetation along the roadside, wet premontane forest, 22 Sept. 2016.

Etymology. From the Latin auriculatus, provided with ears, in reference to the small, ear-like basal lobes of the lip, unique in the genus.

Epiphytic, caespitose, patent to subpendent herb, forming intricate masses of delicate, leafy stems. Roots produced at the base of the vegetative stems (basal) and from the lower nodes along the stem (caulinar); basal roots flexuous, long, c. 1 mm diam; caulinar roots short (the exposed portion usually less than 1 cm long), 0.5–0.7 mm diam. Stems slender, terete, patent to gently pendent, rarely suberect, up to 15 cm long, producing short lateral branches 1.5–4 cm long, completely covered by the conduplicate, tightly to loosely clasping foliar sheaths. Sheaths subrectangular, conduplicate, to 10 by 3 mm, articulate with the leaf, green when young, becoming dry-papyraceous when old. Leaves linear-subacicular, 15–23 by 1.5–2.2 mm, strongly conduplicate, acuminate, the apical margins often touching each other into a false mucron. Inflorescence lateral, 1-flowered, emerging from the axils of the upper leaves and flowering under the leaves, to 20 mm long; peduncle terete, arched, 15–18 mm long, covered at the base by a tubular, acuminate bract to 6 mm long, completely hidden within the leaf-sheath. Floral bract double, the external bract broadly ovate-triangular, c. 3 by 1.5 mm, apex acuminate, deeply cucullate at the base, strongly conduplicate-folded at apex; the inner bractlet ligulate, c. 2.5 by 0.5 mm, apex acuminate. Ovary pedicellate, cylindric, rounded in section, with well-marked valvate ribs, c. 2 mm long including the pedicel. Flowers ephemeral, in anthesis for 1– 2 days, not completely spreading, autogamous, mostly cleistogamous, with sepals and petals white to pale greenish white, the petals faintly suffused with purple, especially along the basal veins, the lip white, the column white tinged with rose-purple toward the apex, with distinct purple stripes along the lateral edges and the stigmatic rims towards the apex of the ligule. Dorsal sepal lanceolate, c. 6 by 2.5 mm, apex acute, 3-veined, concave. Lateral sepals asymmetrically lanceolate, the adaxial half broader, c. 5 by 2.5 mm, apex acute, 3-veined, concave. Petals elliptic-lanceolate, c. 4.5 by 2 mm, apex acute to abruptly short-acuminate, 3-veined, subporrect, incurved. Lip 3-lobed from a short claw, c. 4 by 3.5 mm when spread, the rectangu- lar claw c. 0.3 mm long; the lateral lobes auriculate, c. 0.6 by 0.6 mm, apex rounded, suberect; the midlobe sagittate from a long, obcuneate isthmus; the blade anchor-shaped, rounded, minutely apiculate; the lateral lobes short, truncate; the disc provided with a high, rounded keel from the base of the lip, flushing into the blade at ± the middle portion of the isthmus. Column semiterete, subrectangular in ventral view, c. 4 by 3 mm, around the stigma, apically narrowed into a shallow clinandrium with thin, entire walls; the ventral surface provided with a long, triangular, distinctly bifid, glabrous ligule; the sigma ventral, rounded; the anther frontal sub-incumbent, the tapetum continuous with a massive, triangular, long, attenuate rostellum c. 1 mm long. Anther cap trapezoidal, truncate-emarginate, shallowly cucullate at the base, obscurely 2-celled, c. 0.6 by 1 mm. Pollinia 4, dorsiventrally superposed, almost similar in size, obovate, strongly complanate, c. 0.45 by 0.4 mm, on a triangular, apically long-attenuate stipe of c. 1 by 0.4 mm, and an ovate to rounded, hyaline viscidium of c. 0.3 by 0.2 mm. Fruit an ellipsoid-obovoid, glabrous capsule, c. 7 by 4 mm, the faded floral parts drying in place.

Distribution — Only known from the type locality in Costa Rica.

Habitat & Ecology — Dichaea auriculata is known from a single population, found in the constantly wet and warm region of the Río Tuis, which drains into the Caribbean. Plants of D. auriculata have been observed on shaded branches of the lower canopy, on trees of secondary mature vegetation. Flowering: February to April, but it is probable that, once the stem has reached maturity, the plant may flower at any time of the year.

Conservation status — With the actually available data, we cannot produce a solid assessment about the conservation status of this species. As a result of six field trips in the area where Dichaea auriculata was discovered, we only could observe three plants surely belonging to the species, which were subsequently cultivated and documented at Lankester Botanical Garden. At least locally, D. auriculata is likely not a common species, but if we consider the enormous extent of unexplored, suitable habitats on the Talamanca mountain range, protected within several National Parks and indigenous reserves, then the species is probably more common, but our data prevent any conclusion at this stage.

Kingdom

Plantae

Phylum

Tracheophyta

Class

Liliopsida

Order

Asparagales

Family

Orchidaceae

Genus

Dichaea

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