Myoxanthus anancusiensis H.R. Quispe, R.D. Cuadros & F.H. Calderon, 2023

Cuadros-Rojas, Robinson Daniel, Quispe-Melgar, Harold Rusbelth, Calderon-Quispe, Fernando H. & Singer, Rodrigo B., 2023, Myoxanthus anancusiensis (Orchidaceae: Pleurothallidinae), a new species from the inter-Andean valley of Huancavelica, Peru, Phytotaxa 622 (2), pp. 155-164 : 156-163

Myoxanthus anancusiensis H.R. Quispe, R.D. Cuadros & F.H. Calderon sp. nov. ( Figures 1–3 )

Type:— PERU. Huancavelica: Province Huancavelica, District Acoria; Añancusi locality , 2800 m, Andean shrubland, terrestrial, 07 April 2023, R.D. Cuadros 21 (holotype: HOXA 82218 !; isotype: HSP 14811 !) .

Similar to Myoxanthus serripetalus but is distinguished by having shorter sepals, up to 23 mm long, and having a smooth adaxial surface of the sepals (vs. up to 30 mm long and an adaxial surface of the sepals densely covered with warts), petals oblong with dots towards the caudate apex (vs. obovate at the base, verrucose, denticulate, abruptly contracted above the middle, forming a narrow, oblong to linear apex), lip oblong-elliptic with lateral lobes erect bellow the middle, fimbriate (vs. ovate with lateral lobes erect below the middle and margins serrate to fimbriate and apex verrucose), dorsal sepal oblong, 23 mm long, 9-veined (vs. ovate, 25–30 mm long, 7-veined), lateral sepals oblong-obovate, 23 mm long, 7–9-veined (vs. ovate, 23–28 long, 6-veined) ( Figure 4 ).

Description: —Terrestrial, large, caespitose plants. Roots 2–3 mm diameter, flexuous, cylindrical. Stems/ramicaul erect, stout, 15.6–45.6 cm long, enclosed by 3–5 tubular, hispidulous sheaths. Leaves erect, coriaceous, oblong to narrowly ovate, conduplicate, at apex rounded and retuse, sessile, blade 3.3–4.5 × 17.6–23.9 cm; margin entire, slightly revolute; adaxial surface sulcate along the mid-vein; abscission layer almost at the same level of the inflorescence point of emergence, oblique. Spathe lacking. Inflorescence with single flowers arising at the apex of the ramicaul and opening successively; peduncles 10 mm long in the first two thirds, then curved forming an inverted U, with 5 mm. Floral bracts 3× 5 mm, oblong, acute, papyraceous. Ovary 6.0 mm long, longitudinally sulcate, subclavate; external epidermis with glandular cells. Flowers 2.0 × 4.4 cm, reddish to cherry red with slightly yellowish grooves, fragrance not perceived. Sepals membranous, margins entire, similar in length, adaxial surface irregular, abaxial surface densely covered by pubescent; dorsal sepal 10.0 × 23.0 mm, oblong, acute, slightly concave, 9-veined; lateral sepals connate in the basal 1/2, oblong-ovate and oblique, 10.0 × 23.0 mm, 7–9-veined; synsepal width at apex 20 mm. Petals 4.0 × 12.0 mm, oblong at the basal 2/3, then narrower, margins entire, with dots towards the caudate apex, 5-veined. Lip 5.0 × 10.0 mm, oblong-elliptic, with lateral lobes erect below the middle, fimbriate, deeply concave transversely; edge of lobes at base half yellowish and gradually changing to cherry red; abaxial surface yellowish, cherry-red coloured towards the apex, cherry-coloured dots at the base. Column 12 mm long, yellow to light green towards the apex, stout, concave ventrally, and transversely. Clinandrium-hood short, margin entire. Rostellum flap-like. Stigmatic cavity concave. Anther 2.0 × 2.5 mm, obovate, yellow, 2-celled. Pollinia 2, obovoid, laterally compressed and connected to terminal, flat caudicles; viscidium absent. Capsule 19.0 × 28.0 mm, ellipsoid, pale green, perianth persistent.

Distribution and ecology: —Known presently only from the type collection, from central Peru, Region of Huancavelica, in Yuraccacca and Tinyabamba sector of the locality of Añancusi, but it is likely to find a population of the species near the city of Huamanga, Ayacucho ( Gutierrez 2023) ( Figure 5 ). In a semi-arid, rocky, steep slope environment, the landscape is a typical inter-Andean ecosystem surrounded by a matrix of shrubs, cactus and bromeliads, at 2800 m elevation. Flowering in natural conditions between January-April ( Figure 6 ). Fruit scarcity suggests that this species may be pollinator-dependent.

The type area isn’t currently under protection. In recent years, agriculture is being locally promoted, a fact that may threat not only this orchid but the whole local Flora. Thus, protection measurements like the creation of a Conservation Unit and/or cultivating this species ex-situ for propagation purposes are desirable.

Etymology: —In honor to the Comunidad Campesina de Añancusi, Huancavelica, where the species was collected. Also, the birthplace of the first author and his father and grandparents.

Conservation Status: —DD. Data deficient. Known presently only from the type locality.

Taxonomic discussion:— The species M. anancusiensis is easily recognizable by the entire margin of the oblong and caudate petals, the smooth and irregular adaxial surface of the sepals, having 7–9 veins on the sepals and flowers reddish to cherry red with slightly yellowish grooves. Conversely, M. serripetalus has petals with denticulate appendices at the base and sepals with a verrucose surface, with only 6–7 veins and dark purple flowers, and M. oliviae has subfalcate petals that at the apex contract and expand again to form a sagittate-like structure, connate sepals, deeply concave at the base with 7–8 veins and pale brownish-purple flowers ( Table 1 ).

Specimens examined from other species:— Myoxanthus serripetalus (— PERU. Amazonas: Prov. Bongará, 3 Km. N of North end of Pomacocha Lake, on Rioja road, cool ceja, 2100–2200 m, 05 February 1964, P.C. Hutchison & J.K. Wright 4074 (AMES! F! NY!); Prov. Chachapoyas, Carros Calla Calla 5 Km. above Laimebamba on the road to Balsas , region called San Miguel , 2400 m, 26 March 1964, P.C. Hutchison & D.E. Bennett 4560 (AMES! F! NY!); Apurimac: Prov. Andahuaylas, Quebrada Posocoi , 06 January 1950. C. Vargas C. 8790 (AMES! MO!); Cusco: Prov. Calca , entre Lamai y Calca, 1950 m, 07 February 1943, C. Vargas C. 3196 (AMES!); Prov. Urubamba, Huayllabamba , Lagunas Yanacocha y Quellococha hacia San Juan , NE de Cusco. 13°16’S 72°04’W, 2940–4600 m, 19 August 1989, A. Tupayachi & W. Galiano 1216 (MO!); Machu Picchu, east of ruins, 04 April 1965, L.A. Garay 745 (AMES!); camino Inca, 2560 m, 11 April 1963, C. Vargas C. 14372 (AMES!); Urubamba Valley , 2800 m, April 1932, F.L. Herrera 3484 (AMES!); Ollantaytambo, 3000–3100 m, 26 April 1925, F.W. Pennell 13641 (AMES!); Slightly below the ridgeline on which the ruin of Ollanta sits, 3660 m, 21 April 1982, B. Peyton & S. Tilney Peyton 18 (MO!); Junin: Prov. Huancayo. epiphytic in the valley of Pariahuanca between Panti and Rocchac, alt. 2400–2600 m, A. Weberbauer 6538 (holotype: F!). Myoxanthus oliviae — PERU. Cusco: Prov. Urubamba, 3100 m, 5 December 1968, C. Vargas C. 20860 (holotype: AMES!); a 67 km de Cusco, desde el Rio Calicanto hacia Chacchapata, Muris y sus alrededores. 13˚16’00”S 72˚16’W, 2700–3020 m, 21 November 1987, P. Núñez V. & E. Bengoa 8670 (F! NY! MO!); Ollantaytambo, rocky hillsides above town, 9200 ft., 17 January 1975, T. Plowman & K. W. Davis 4740 (AMES!) .

Figures

FIGURE 1. LCDP of Myoxanthus anancusiensis H.R.Quispe, R.D.Cuadros & F.H.Calderon. A. Habit and flowers. B. Apical sheaths of the ramicaul. C. Basal sheaths of the ramicaul. D. Flower, front view. E. Dissected perianth. F. Flower, lateral view. G. Pubescent of sepal. H. Column, ovary, and lip, lateral view. I. Column and ovary, longitudinal section. J. Lip, lateral, front, and back view. K. Details of fimbriate lip margins. L. Fruit. M. Pollinarium, front, back, and lateral view. N. Anther, front and back view. Photographs by Harold Rusbelth Quispe-Melgar based on holotype.

FIGURE 2. Holotype of Myoxanthus anancusiensis H.R.Quispe, R.D.Cuadros & F.H.Calderon. Specimen deposited in the HOXA Herbarium. Photographed by Shane Verde.

FIGURE 3. Isotype of Myoxanthus anancusiensis H.R.Quispe, R.D.Cuadros & F.H.Calderon.Specimen deposited in the HSP Herbarium. Photographed by Daniel Ramos.

FIGURE 4. Comparison of diagnostic floral features. A. M. anancusiensis and B. M. serripetalus. Photographs by Robinson Daniel Cuadros-Rojas (A) and Luis Enrique Egoavil (B).

FIGURE 5. Distribution map of Myoxanthus anancusiensis H.R.Quispe, R.D.Cuadros & F.H.Calderon and the most similar species M. serripetalus and M. oliviae in Peru. The red asterisk indicates a record that needs to be corroborated.

FIGURE 6. Myoxanthus anancusiensis in situ. A. Habit. B. Flower. C. Habitat. Photographs by Robinson Daniel Cuadros-Rojas.

Tables

TABLE 1. Comparison of Myoxanthus anancusiensis with closely related species M. serripetalus and M. oliviae.

Characters	M. anancusiensis	M. serripetalus	M. oliviae
Flower color	Reddish to cherry red, with slightly yellowish grooves	Dark purple	Pale brownish-purple, internally intensively suffused with yellow
Flower surface	Only covered with red dots on the petals	Densely covered with dark-purple warts	Densely covered with brown warts
Shape of dorsal sepal	Oblong, acute, slightly concave	Ovate, the apices acute and diverging	Ovate-lanceolate, subobtuse at apex, concave in the center
Length of dorsal sepal	21–23 mm	25–30 mm	17–22 mm
Number of dorsal sepal veins	7–9	7	5–7
Shape of lateral sepals	Oblong-ovate	Ovate	Oblique-ovate
Length of lateral sepals	21–23 mm	25–30 mm	16–25 mm
Number of lateral sepal veins	7–9	6	7–8
Shape of petals	Oblong with dots towards the caudate apex	Oblong at the base, denticulate, abruptly contracted above the middle, forming a narrow, oblong to linear apex.	Contracted below the apex and expanded again into a sagittate apex
Length of petals	10–13 mm	10–11 mm	7.5–10.5 mm
Number of petal veins	3 to 5 veined	-	3-veined
Edge of the lip	Slightly fimbriate on the lateral lobes	Fimbriate on mid and lateral lobes	Strongly fimbriate on the lateral lobes