Lepanthes calochroma Thoerle & Hirtz, 2015

Thoerle, Lisa & Hirtz, Alexander C., 2015, Three new Lepanthes species (Pleurothallidinae, Orchidaceae) from Ecuador, Phytotaxa 201 (1), pp. 50-62 : 52-54

Lepanthes calochroma Thoerle & Hirtz , sp. nov., Figs. 1 , 2 .

Type:— ECUADOR. Collecting data otherwise unknown, flowered in cultivation by Mario Portilla at Ecuagenera, Gualaceo, Ecuador, November 2010, Hirtz 10397 (holotype: MO!), L. Thoerle illustr. 300.

Diagnosis: — Lepanthes calochroma is similar to L. golbasto Luer & Hirtz (1985: 164) , but the plant is larger; the flowers are brilliantly colored with bright yellow and red petals with an upper lobe longer than the lower; and the lip with irregular margins is broadly ovate, with a ligulate, descending appendix. It is distinguished from L. imposita Luer & R.Escobar (1985: 56) by much smaller flowers that are brightly colored, held closely against the rachis by shorter pedicels.

Plant medium in size for the genus, presumably epiphytic, caespitose; roots slender. Ramicauls stout, erect to suberect, 2–4 cm long, enclosed by 6–7 minutely ciliate-spiculate lepanthiform sheaths. Leaf erect to nearly horizontal, thinly coriaceous, elliptical, apex shortly acuminate, triapiculate, 3–3.5 × 1–1.6 cm dried, the base rounded, contracted into a petiole 3–5 mm long. Inflorescence a more or less horizontal, loose, flexuous, gradually lengthening, successively single-flowered raceme with up to at least 8 flowers, to at least 6 cm long including the filiform peduncle 4–15 mm long, borne behind the leaf; floral bracts acuminate, ca. 2 mm long; pedicels 1 mm long, ca. 5 mm apart; ovary with ribs thick, irregular, 1 mm long; flowers held close to the rachis, sepals dull pink with translucent greenish-yellow margins, minutely papillose with denticulate margins, externally carinate-verrucose, the dorsal sepal ovate, acute, shortly acuminate, 5 × 3 mm, 3-veined, connate to the lateral sepals for 1 mm, the lateral sepals diverging, ovate, oblique, acute, shortly acuminate, 5 × 2 mm, 2-veined, connate 2 mm; petals with central portion bright yellow, apical portions bright red with apex of upper lobe darker red, minutely pubescent, transversely bilobed, 1 mm × 3.8 mm, with a small, marginal obtuse angle between the lobes, the upper lobe oblong, slightly narrowed below the rounded, incurved apex, 2.3 mm long, the apices of the opposite petals overlapping above the column, the lower lobe obliquely triangular, obtuse, incurved, 1.5 mm long; lip dark red, densely pubescent, bilaminate, the blades broadly ovate, irregular, with obtuse ends, the apical margin with long cilia, bases recurved, 1.3 × 2.2 mm expanded, the connectives broadly cuneate, the body connate to the base of the column, the sinus obtuse with a small, ligulate, descending, ciliate appendix rising from a cluster of cilia; column purple, 1.25 mm long, with the anther apical and the stigma ventral, anther cap lavender, pollinia yellow.

Distribution: —Known only from the type collection.

Etymology: —From the Greek calo, “beautiful,” and chroma, “color,” for the beautiful colors of the flowers.

Discussion: —The robust ramicauls of Lepanthes calochroma , clad in lepanthiform sheaths with dilated, shortly ciliate-spiculate ostia, support elliptical leaves with a short, acuminate apex. The centimeter-long flowers are borne by a lengthening, loose raceme, with about 5 mm between floral bracts. The usually horizontal flower is held close to the rachis. The ovate sepals have decoratively denticulate margins forming a narrow border of yellow-green surrounding the dull pink blades. The central area of the brilliantly colored petals flanking the deep red blades of the lip is bright yellow, with the apices of both lobes bright red.

This species resembles the tiny Ecuadorian Lepanthes golbasto ( Fig. 3 ), with the elongate raceme of both species bearing similarly sized and shaped flowers with pink sepals and bicolored petals overlapping above the column. Lepanthes calochroma is distinguished by the larger plant, which can reach a height of at least 4 cm rather than 2.5 cm; flowers with more brilliantly colored petals with the upper lobe longer than the lower lobe, rather than subequal in length; and a lip with blades broadly ovate rather than ovate, and with a narrow, recurved, descending appendix, rather than a thick, uncinate, incurved appendix. The Colombian L. imposita ( Fig. 4 ), has similarly shaped petals surrounding a lip with somewhat similar blades, but is readily distinguished by a flower nearly twice as large, with a natural height of 17 mm, and a more uniform palette of purple and red.

Figures

FIGURE 1. Lepanthes calochroma. A. Habit. B. Flower with partial inflorescence. C. Dissected flower. D. Lip with column, dorsal view. E. Lip expanded with column, dorsal view. F. Lip expanded with column lifted. G. Ovary, lip, and column, profile. Drawn by L. Thoerle from the holotype, Hirtz 10397 (MO).

FIGURE 2. Lepanthes calochroma. Flower from a cultivated plant. Photographed by A. Hirtz from the plant that provided the holotype specimen.

FIGURE 3. Lepanthes golbasto. Drawn by C.A. Luer from the holotype, Hirtz 1692 (MO). Reprinted with the kind permission of C.A. Luer and the American Orchid Society.

FIGURE 4. Lepanthes imposita. Drawn by C.A. Luer from the holotype, Luer et al. 7671 (SEL). Reprinted with the kind permission of C.A. Luer and the American Orchid Society.