Bulbophyllum physometrum J.J.Vermeulen, Suksathan & Watthana, 2017

Vermeulen, Jaap J., Suksathan, Piyakaset & Watthana, Santi, 2017, A new species and new section in Bulbophyllum (Orchidaceae; Epidendroideae; Malaxideae), Phytotaxa 302 (2), pp. 174-180 : 174-179

publication ID	https://doi.org/ 10.11646/phytotaxa.302.2.7
persistent identifier	https://treatment.plazi.org/id/D1528795-1D71-FF88-FF15-F855AA71FDCC
treatment provided by	Felipe
scientific name	Bulbophyllum physometrum J.J.Vermeulen, Suksathan & Watthana
status	sp. nov.

Treatment

Bulbophyllum physometrum J.J.Vermeulen, Suksathan & Watthana View in CoL , sp. nov. ( Figs. 1–3 View FIGURE 1 View FIGURE 2 View FIGURE 3 )

Type:— THAILAND. Mae Hong Son Prov., Muang District, Ban Rakthai , cultivated at Queen Sirikit Botanic Garden , Chiang Mai, Suksathan 4243 (holotype: QBG; isotypes: BKF, C) .

Small, (long-)creeping epiphytic herb. Rhizome 1.0– 1.5 mm diam., sections between pseudobulbs 3.0–5.0 cm long, rhizome scale fibers thin, deciduous; roots sprouting mainly below the pseudobulbs, glabrous. Pseudobulbs distinct, ovoid to discoid to almost globose, 0.4–1.2 × 0.9–1.4 cm, usually with a few longitudinal grooves. Leaf with a petiole up to 2 mm long; blade ovate to elliptic, 2.0–3.5 × 0.9–1.2 cm, ratio length/width 2.0–2.9, acute. Inflorescence 6–10 cm long, 5–7(–9)-flowered. Peduncle 4.0–7.0 cm long, scales 4–5, the longest 5.0– 6.5 mm. Rachis porrect or arching, somewhat spindle-shaped, c. 4.0 × 1.2 mm. Floral bracts 2.5–4.0 mm long, acute. Flowers (apical flower excepted) with pedicel plus ovary 11–14 mm long; basal node 1.5–2.0 mm above the floral bract attachment. Median sepal porrect to moderately recurved, concave towards the apex, obovate-oblong, 2.4–3.0 × 2.0– 2.3 mm, ratio length/width 1.2–1.3; rounded, slightly apiculate or not, margins entire; glabrous, 3-veined. Lateral sepals as the median but recurved, ovateoblong with a slightly widened base, 2.5–3.2 × 2.0– 3.1 mm, ratio length/width 1.0–1.3; rounded, 5-veined. Petals porrect, slightly recurved, slightly downwards falcate, obovate-oblong, 2.0–3.1 × 0.3–0.7 mm, ratio length/width 4.4– 6.7; acuminate, margins entire; glabrous, 1-veined. Lip recurved towards the base, (obovate-)oblong in outline, 1.5–2.9 × 1.4–2.4 mm, ratio length/width 1.0–1.4 (without spreading); rounded, margins entire, ciliate; adaxially near the base slightly concave and with two slight, flat calli, adaxial surface otherwise convex, (minutely) hirsute towards the apex; abaxially with a median ridge with a more or less flat crest from the base to almost the apex, surface glabrous. Column including stelidia 2.0– 2.5 mm long. Stelidia porrect, approx. subulate with a slightly widened base, 0.5–0.7 mm long, acute, near the base with a narrow, seam-like wing. Anther 0.5–0.7 mm long, abaxially with a low, wide, flat ridge, connectivum not drawn out in front. Pollinia 4; 0.4–0.5 mm long, inner pair slightly shorter than the outer pair. Apical flower as the other flowers, but with the ovary swollen up to c. 25 × 14 mm, thin-walled, ellipsoid, in transverse section triangular body during anthesis of the other flowers; perianth closed, parts smaller than the other flowers: sepals c. 1.0 mm long. Colours: pseudobulbs and leaves glossy green. Peduncle, rachis, pedicel and ovary pale green, suffused red. Floral bracts green. Sepals whitish, suffused red and with two red spots near the base, veins green, partly purple-red. Petals white to light green, vein green. Lip white in the center, green towards the margins, dark red towards the base, with large, dark red blotches elsewhere. Apical flower pale red to pale orange.

Ecology:— Epiphyte on oak trees in lower montane forest, 1100–1160 m; flowering observed in March–May.

Distribution:— Thailand, northern part, Mae Hong Son Province, next to the Myanmar border, between Ban

Napapak and Ban Rakthai villages.

Other material seen:— Thailand, Mae Hong Son Prov., Muang Dist., Ban Napapak Village, cultivated at Queen

Sirikit Botanic Garden, Chiang Mai, Watthana 4258, leg. Pitak (C!).

Vernacular name:— “Sing to tang hoo (สงโตตางห)”, meaning “Dangle Earings Bulbophyllum ”.

Etymology:— Physos (Gr.) = blister, metra (Gr.) = womb.

Proposed IUCN conservation assessment:— Critically Endangered (IUCN 2012: ENB2 ab(iii,v)). A careful search yielded only two trees with the species, approx. 6 km apart, in the same mountain range not far from hill-tribe villages. Agriculture and tourism progressively degrade and fragment the forest in the area.

Notes:— The swollen and sterile ovary of the apical flower develops well before anthesis of the other flowers. It is distinguishable even in young inflorescences. It swings in the smallest draft of wind; how this relates to the pollination of the species needs investigation.