Bulbophyllum radula 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 : 324-327

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

( Fig. 16 )

Bulbophyllum “ subcubium (?) ”, Dressler, The Orchids, Pl. 13, fig. 73 (1981) [probably a spelling mistake for B. subcubicum J.J.Sm. , an unrelated species].

TYPE: Papua New Guinea, Enga Province, Lagaip District, Yokotapus North of Laiagam station, 2400 m, March 1983, Reeve 762 (holotype L!; isotypes CANB, E!, K!, LAE, NSW).

DIAGNOSIS. Within series C, it shares a rhizome with rather densely set pseudobulbs combined with an abaxially hirsute lip with Bulbophyllum atroviride J.J. Verm. and B. planiplexum J.J. Verm. Bulbophyllum radula differs by the succulent, semi-terete leaves (thin and dorsoventrally flattened in the others), the (ovate-) oblong, rounded petals (ovate-triangular and acute in B. atroviride ), and the wide lip (ratio length/width 1.5–1.8, versus 5.5–5.8 in B. planiplexum ).

Medium-sized epiphyte with patent to pendulous, sparsely branched rhizomes to 30 cm long, over which the roots grow towards its base. Rhizome 1.1–2.0 mm diam., sections between pseudobulbs 0.4–0.9 cm long, arising from the basal node of the pseudobulb; rhizome scales thin, rather persistent. Pseudobulbs distinct, ellipsoid to (ob-)ovoid, 0.6–1.1 × 0.3–0.4 cm, hardly angular but deeply concave on the side where the new shoot arises. Leaf: petiole 1.5–2.8 mm long; blade succulent, semi-terete with the adaxial side flattened, ovate in outline, 17–22 × 3.5–7.0 mm, ratio length/width 3.1–4.9; acute. Inflorescences clustered, ca. 1 cm long, 1-flowered. Peduncle ca. 1.4 mm long, scales 1. Floral bracts ca. 3.1 mm long. Flowers: pedicel plus ovary ca. 3.8 mm long, basal node 1.0– 1.5 mm above the floral bract attachment. Median sepal free, recurved, ovate-triangular, 4.8–6.0 × 1.8–2.3 mm, ratio length/width 2.2–2.8; acuminate, margins entire, ciliolate, surface glabrous; 3-veined. Lateral sepals as the median but 4.3–5.6 × 2.3–2.9 mm, ratio length/width 1.8–2.0. Petals porrect, (ovate-)oblong, 2.5–2.7 × 0.6–0.8 mm, ratio length/width 3.2–4.2; rounded, margins entire, ciliate, surface glabrous; 1-veined. Lip recurved in the basal half, obovate, 1.9– 2.4 × 1.1–1.6 mm, ratio length/width 1.5–1.8 (without spreading); rounded, margins entire, glabrous; very thick; adaxially concave proximally with a transverse, rounded callus just above the ligament, with two thin, narrow ridges which start near the base, close to the margin, then converge slightly over the adaxial surface up to approx. half-way the length of the lip, where they merge with the distinctly convex distal part of the lip, adaxial surface glabrous; abaxially with two distinct, rounded, hirsute ridges which are adjacent proximally and distally, distant and with a deep furrow in between elsewhere. Column including stelidia 1.6–2.1 mm long, stigma narrowly elliptic with slightly protruding base, foot distally with spreading, rounded lateral teeth. Stelidia downwards falcate, narrowly triangular, subulate distally, 0.8–1.2 mm long, acute. Pollinia 4, the inner more than half as long as the outer.

COLOURS: tepals proximally white, sepals distally finely spotted brown-purple, petals distally purple. Labellum shiny purple.

ETYMOLOGY: radula (Latin, a noun in apposition) = a grater, referring to the general shape of the plant.

HABITAT AND ECOLOGY: epiphyte, no further details. Elevation 2400 m.

Figures

FIGURE 16. Bulbophyllum radula J.J.Verm., Schuit. & de Vogel. a. Habit. b. Flower. c. Flower analysis, from left to right: median sepal, petal, lateral sepal, lip. d. Petal. e. Lip, left: adaxial side, right: abaxial side. f. Column and lip, lateral view.g. Column, frontal view. h. Anther, above: adaxial side, below: abaxial side. i. Pollinia, left: two pairs, right: one pair. Drawn from Reeve 762 by © J.J. Vermeulen, from herbarium material.