Ophioglossella
(Orchidaceae - Aeridinae)
a new genus from Papua New Guinea

A. Schuiteman¹ & P. Ormerod²

Summary: The new genus Ophioglossella Schuit. & Ormerod (Orchidaceae - Aeridinae), from Papua New Guinea, with the single species O. chrsysostoma, is described and illustrated.

Introduction: In the highlands of Papua new Guinea an evidently undescribed orchid belonging to subtribe Aeridinae has been found on several occasions in widely scattered localities, but almost always, it seems, in very low numbers. The scarce material in herbaria (four out of five collections are unicates) was identified as Sarcochilus, Pteroceras, Dryandorchis or Grosourdya. Two of the genera (Pteroceras and Grosourdya) are not know to occur in New Guinea, and the New Guinea members of Sarchochilus probably constitute a separate genus. The specimens we have seen are rather variable in the size and shape of the leaves, but they agree in the unusually complex morphology of the labellum. Our attempts to find a genus in which this strange orchid could be accommodated failed, and we concluded (at first independently) that it belonged to an as yet undescribed genus.

This so far montypic genus, which we propose to call Ophioglossella, does show similarities with each of the four genera mentioned above. These in turn belong to a larger group of genera within the subtribe Aeridinae that are distinguished by having a mobile labellum, hinged with the apex of a distinct column-foot. Most genera in this group are small, distinctive, und unlikely to be confused with Ophioglossella. A key to those genera with which a closer comparison is justified is provided below.

KEY TO GENERA RELATED TO Ophioglossella

1. Pollinia 2, entire or partly cleft. Labellum with a hollow spur, without callosities inside. Inflorescence muricate or not . . . . . . . . . . . . . . . . . . 2
Pollinia 4. Labellum with or without a hollow spur, with or without callosities inside. Inflorescence not muricate . . . . . . . . . . . . . . . . . . . . . . . . . . 5
2. Pollinia entire. Column rather long, distinctly bent forwards at the base of the stigma. Inflorescence muricate . . . . . . . . . . . . . . . . . . . . . . Grosourdya
Pollinia cleft. Column variable. Inflorescence muricate of not . . . . . . . . . . 3
3. Column-foot much shorter than the column. Inflorescence glabrous. Floral bracts narrower than the rachis . . . . . . . . . . . . . . . . . . . . . . Brachypeza
Column-foot about as long as the column or longer. Inflorescence muricate or not. Floral bracts as broad as the rachis . . . . . . . . . . . . . . . . . . . . .. . . 4
4. Labellum with a distinct basal claw, abruptly bent upwards relative to the column-foot . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..Macropodanthus
Labellum not clawed, continuing the lione of the column foot . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Pteroceras (p.p.)
5. Labellum with a hollow spur. Column short with a long foot. . . . . . . . . . 6
Labellum without a hollow spur. Column variable . . . . . . . . . . . . . . . . . . . 7
6. Flowers ephemeral. Spur continuing the line of the column-foot . . . . . .Pteroceras (P. leopardinum (C.S.P. Parish & Recihb. F.) Seidenf. & Smitinand)
Flowers longer-lasting. Spur making a distinct angle with the line of the column-foot . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Sarcochilus (p.p.)
7. Rachis of inflorescence swollen. Flowers ephemeral. Central concavity of the labellum without a pair of calli. Column long and slender, with a short foot (much less than half as long as the column proper) . . . . . . . . . . . Dryadorchis
Rachis of inflorescence not swollen. Flowers not ephemeral or longevity not known. Central concavity of the labellum with a pair of calli. Column either short or long and slender, but always with a column-foot (almost half as long as the column proper or more) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
8. Mid-lobe of the labellum directly connected with the lateral lobes through a pair of lamellae. Column long and slender, curved; foot less than half as long as the column proper. Rostellum much elongated, furcate . . . . . . Ophioglossella
9. Mid-lobe of the labellum not directly connected with the lateral. Column short, straight; foot at least as long as the column proper. Rostellum short, bidentate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Sarcochilus (p.p.)

Ophioglossella Schuit. & Ormerod gen. nov. Herbae monopodiales epiphyticae. Folia subfalcata basi torta plus quam 90^o plus minusve in aequo patentia. Racemi laxi. Labellum mobile 3-lobatum valde concavum carnosissimum ecalcaratum, in medio duobus callis brevibus parallellis, lobis lateralibus lamellis conspicuis lobo centrali conjugates. Columna longa gracilis curvata glabra pede conspicuo. Rostellum elongatum apice furcata. Pollinia 4 discreta binatim intra parem distincte inaequalia. Type species: Ophioglossella chrysostoma Schuit. & Ormerod.

Small, rather short-stemmed, monopodial epiphytic herbs. Leaves sub-falcate, twisted at the base through 90^o and more or less spreading in one plane. Inflorescence a lax, few- to several-flowered raceme with angular, not swollen rachis arising singly from the lower part of the stem. Flowers opening a few at a time, c. 1.5 cm across, longevity unknown. Labellum hinged to the apex of the column-foot, 3-lobed, strongly concave, very fleshy, not spurred, in the centre with two short parallel calli, the lateral lobes connected to the mid-lobe by two conspicuous lamellae. Column long and slender, curved, glabrous, with a distinct foot about half as long as the column proper. Rostellum elongated, furcate. Pollinia 4, separate, in two pairs, those of a pair distinctly unequal.

Distribution: Papua New Guinea, endemic (one of the collections is from close to the border with Irian Jaya, so it may well occur there).

The spurless labellum, hinged to the apex of a distinct column-foot seems to indicate an affinity with Sarcochilus and Dryadorchis, both also with 4 pollinia. Moreover, Sarcochilus agrees in the presence of two calli in the centre of the labellum (at least in the spurless species). In Sarcochilus the column is not long and slender, nor is it much longer than the column-foot, as it is in Ophioglossella. The rostellum is short, bidentate or tridentate in Sarcochilus; it is elongated and fork-shaped in Ophioglossella. Dryadorchis (Schuiteman & Christenson 1995) has a short column-foot, de dentate rostellum and lacks the two calli in the centre of the labellum; the pollinia form two globose masses, not four separate masses as in Ophioglossella, and the rachis of the inflorescence is strongly swollen in Dryadorchis. Unfortunately the longevity of the flowers of Ophioglossella is not known. They are ephemeral in Dryadorchis, longer-lasting in Sarcochilus. Ophioglossella is very different form both Grosourdya and Pteroceras, as should be apparent from the key.

The name Ophioglossella, meaning 'little snake's tongue', refers to the shape of the rostellum, which is especially suggestive in conjunction with the cobra-like appearance of the column.

Ophioglossella chrysostoma Schuit. & Ormerod sp. nov. Folia acuto-acuminata apice inaequaliter bidentate. Flores c. 1.5 cm diametro. Labellum glabrum, lobis lateralibus erectis magnis rotundatis, lobo centrali abrupte erecto elliptico obtuso, in medio crista angusta e basi ad parum infra apicem, abaxaliter sulcato. Typus: Papua New Guinea, enga Prov., Porgera Distr., Tagoba & Piawe, alt. 1800 m, March 1982, Reeve 647 (holotypus K!, spirit material; isotypi K!, L!, LAE!; AMES, CBG, E, n.v.).

Grosourdya sp., T.M. Reeve, Orchadian 9: 196 (1989) (colour photograph)

Species line drawing: Ophioglossella chrysostoma

Roots from the basal part of the stem, glabrous, not branching, 1.5 - 2.5 mm thick. Stem unbranched, patent, 2.5 - 10 cm long, densely 4 - 8-leaved. Leaves obliquely elliptic to linear-elliptic, subfalcate, 2.5 - 12 x 0.6 - 2 cm, acute-acuminate, apex unequally bidentate. Inflorescence patent, 7.5 - 12 cm long, peduncle somewhat shorter than the rachis; rachis slightly flexuose, angular, 7 - 13-flowered. Floral bracts patent, ovate, 2.8 - 5 mm long, acute. Pedicel and ovary c. 7 mm long, terete, curved, glabrous. Flowers c. 1.5 cm across. Sepals white suffused with purple, becoming pink (buds much darker). Dorsal sepal elliptic, obtuse, 9 x 4.9 mm. Lateral sepals patent, obliquely broadly ovate, obtuse, 8.3 x 6 mm. Petals white suffused with purple, becoming pink, porrect, narrowly obovate-oblong, slightly oblique, obtuse, apex minutely irregularly denticulate, 7.8 x 3 mm. Labellum whitish, lobes rich purple, calli and central concavity golden yellow, 3-lobed, glabrous, strongly concave in the centre, 5.5 x 3.6 mm, at the base with a very short claw 0.3 mm long hinged to the top of the column foot, in the centre with two parallel calli 1.3 mm long; lateral lobes erect, ovate-oblong, rounded, 3.4 x 2.7 mm, at base 1.3 mm above the base of the labellum connected by a low transverse septum, each of the lateral lobes connected to the midlobe by a conspicuous longitudinal lamella; midlobe abruptly erect, elliptic, obtuse, 4 x 2.9 mm, along the median with a narrow crest from the base to a little below the apex, sulcate abaxially. Column whitish, slender, 6.7 mm long, 2.6 mm wide near the apex, curved, somewhat dilated to the top, in front near the base with two longitudinal ridges; foot making an angle of about 120 degrees with the stalk of the column, 2.5 mm long. Stigma large, suborbicular. Rostellum elongated, furcate, 1.4 mm long. Anther whitish, rostrate, 2.5 by 1.7 mm; stipe narrowly obtriangular, 2.2 mm long; viscidium broadly elliptic, 0.6 mm long. Pollinia 4, the two larger ones 1 by 0.8 mm, the two smaller ones 0.8 bt 0.6 mm, white. Fruit not seen. Fig. 1

Distribution: Papua New Guinea, widespread but not common

Additional collections examined: West Sepik prov., Mogofogola R. near Folongonom, alt. 2000 m, Vinas in LAE 59593 (LAE); Morobe Prov., Bulldog Road, alt. 2275 m, Streimann & Kairo in NGF 21078 (LAE); Morobe Prov., Boana, alt. 1700 m, van Royen & Millar in NGF 17514 (LAE); Eastern Highlands Prov., Goroka, alt. 2100 m, Millar in NGF 22569 (LAE).

Habitat: Epiphyte in montane forest, also in secondary regrowth. Altitude 1700 - 2300 m.

Note: The epithet chrysostoma, golden mouth, refers to the golden yellow interior of the concave labellum.

Acknowledgements: We would like to thank the directors and keepers of K, L and LAE for allowing us to study the material cited in this paper. Dr. J.F. Veldkamp kindly translated the diagnosis into Latin.

Reference
Schuiteman, A. & E.A. Christenson. (1995). A synopsis of Dryadorchis Schltr. (Orchidaceae). Blumea 40: 421 - 424

This new genus description was first published in the Kew Bulletin Vol. 53(3), (1998) p. 741-745

¹ Rijksherbarium/Hortus Botanicus, P.O. Box 9514, 2300 RA Leiden, The Netherlands
² P.O. Box 8210, Cairns 4870, Australia