Bulbophyllum cerastes J.J.Verm., Schuit. & de Vogel

Vermeulen, Jaap J., Schuiteman, André & De Vogel, Edward F., 2020, Sixteen new species of Bulbophyllum section Polymeres (Orchidaceae) from New Guinea, Lankesteriana 20 (3), pp. 301-330 : 301-304

Bulbophyllum cerastes J.J.Verm., Schuit. & de Vogel , sp. nov.

( Fig. 2 )

TYPE: Indonesia, Papua Province, Vogelkop Peninsula, Ije River, central Tamrau Range , S slope of Mount Kusemum, ascent from Sudjak village , 1100 m alt., 8 Nov. 1961, Van Royen, Sleumer & Schram 7803 (holotype L!).

DIAGNOSIS. Within section Polymeres uniquely identified by the distinct, retrorse horns formed by the lateral lobes of the lip. It shares this character with Bulbophyllum trutiniferum J.J.Verm., Schuit. & de Vogel , a species intermediate between section Brachypus and section Polymeres , but it differs from that species by the free (versus proximally adherent) sepals and the wide (ratio length/width ca. 1.5, versus 4–5), distally papillose (versus glabrous) petals.

Medium-sized epiphyte with creeping rhizomes and spreading roots. Rhizome ca. 5 mm diam., sections between pseudobulbs 0.5–1.0 cm long, arising from the basal node of the pseudobulb; rhizome scales thin, little persistent. Pseudobulbs distinct, ovoid, 1.7–3.5 × 0.7–1.2 cm, hardly angular. Leaf: petiole 16–20 mm long; blade elliptic to obovate, 10.5–16.0 × 2.5–4.1 cm, ratio length/width 3.4–5.2; acuminate. Inflorescences few to many together, 3.5–4.5 cm long, 1-flowered. Peduncle 0.8–1.9 cm long, scales ca. 3. Floral bracts 4.0– 5.2 mm long. Flowers: pedicel plus ovary 1.5–1.6 cm long, basal node ca. 4.2 mm above the floral bract attachment. Median sepal free, recurved, elliptic, ca. 9.0 × 4.0 mm, ratio length/width 2.2–2.3; acute, margins entire; glabrous, 5-veined. Lateral sepals as the median, but elliptic-ovate, ca. 9.8 × 5.8 mm, ratio length/width 1.6–1.7. Petals porrect, obovate, ca. 3.0 × 2.0 mm, ratio length/width ca. 1.5; obtuse, margins approx. entire, papillose distally, adaxial surface papillose distally; 1-veined. Lip recurved approx. halfway its length, 3-lobed, elliptic-obovate in outline with projecting, retrorse, distally slightly downwards falcate, narrowly triangular, obtuse, glabrous, thin lateral lobes attached to the median lobe slightly below half-way its length; median lobe, ca. 2.6 × 1.6 mm, ratio length/ width 1.6–1.7 (without spreading); acute-acuminate, margins entire, ciliate beyond the attachment of the lateral lobes; thick; adaxially approx. flat proximally, distally with two rounded ridges which start close to the margins just in front of the lateral lobe attachment, then converge, meet and continue as a single median ridge to near the apex of the lip, adaxial surface glabrous; abaxially convex and glabrous proximally, slightly convex distally and increasingly hirsute towards the margins. Column including stelidia ca. 2.6 mm long, stigma obovate, proximally with a thickened edge which does not protrude from the lower margins of the column when the latter is viewed laterally, foot slightly widened, with small, patent, obtuse lateral teeth. Stelidia straight, narrowly triangular, ca. 1.1 mm long, acute. Pollinia 4, the inner more than half as long as the outer.

COLOURS: flowers white.

ETYMOLOGY: kerastes (Greek) = with horns, referring to the lateral lobes of the lip.

HABITAT AND ECOLOGY: epiphyte on dead tree in forest. Elevation 1100 m.

Figures

FIGURE 2. Bulbophyllum cerastes J.J.Verm., Schuit. & de Vogel. a. Habit. b. Inflorescence. c. Flower analysis, from left to right: median sepal, petal, lateral sepal, lip. d. Petal. e. Lip, above: adaxial side, below: abaxial side. f. Column and lip, lateral view. g. Anther, left: adaxial side, right: abaxial side. h. Pollinia, left: two pairs, right: one pair. Drawn from Van Royen, Sleumer & Schram 7803 by © J.J. Vermeulen, from herbarium material.