Phillip Cribb

Molecular phylogenetics and morphological reappraisal of the Platanthera clade (Orchidaceae: Orchidinae) prompts expansion of the generic limits of Galearis and Platanthera

BACKGROUND AND AIMS The Platanthera clade dominates the North American orchid flora and is well represented in eastern Asia. It has also generated some classic studies of speciation in Platanthera sections Platanthera and Limnorchis. However, it has proved rich in taxonomic controversy and near-monotypic genera. The clade is reviewed via a new molecular phylogenetic analysis and those results are combined with brief reconsideration of morphology in the group, aiming to rationalize the species into a smaller number of larger monophyletic genera and sections. METHODS Nuclear ribosomal internal transcribed spacer (ITS) sequences were obtained from 86 accessions of 35 named taxa, supplemented from GenBank with five accessions encompassing a further two named taxa. KEY RESULTS Using Pseudorchis as outgroup, and scoring indels, the data matrix generated 30 most-parsimonious trees that differed in the placement of two major groups plus two closely related species. Several other internal nodes also attracted only indifferent statistical support. Nonetheless, by combining implicit assessment of morphological divergence with explicit assessment of molecular divergence (when available), nine former genera can be rationalized into four revised genera by sinking the monotypic Amerorchis, together with Aceratorchis and Chondradenia (neither yet sequenced), into Galearis, and by amalgamating Piperia, Diphylax and the monotypic Tsaiorchis into the former Platanthera section Platanthera. After further species sampling, this section will require sub-division into at least three sections. The present nomenclatural adjustments prompt five new combinations. CONCLUSIONS Resolution of major groups should facilitate future species-level research on the Platanthera clade. Recent evidence suggests that ITS sequence divergence characterizes most species other than the P. bifolia group. The floral differences that distinguished Piperia, Diphylax and Tsaiorchis from Platanthera, and Aceratorchis and Chondradenia from Galearis, reflect various forms of heterochrony (notably paedomorphosis); this affected both the perianth and the gynostemium, and may have proved adaptive in montane habitats. Floral reduction was combined with lateral expansion of the root tubers in Piperia and Diphylax (including Tsaiorchis), whereas root tubers were minimized in the putative (but currently poorly supported) Neolindleya-Galearis clade. Allopolyploidy and/or autogamy strongly influenced speciation in Platanthera section Limnorchis and perhaps also Neolindleya. Reproductive biology remains an important driver of evolution in the clade, though plant-pollinator specificity and distinctness of the species boundaries have often been exaggerated.

A revision of Gastrodia (Orchidaceae: Epidendroideae, Gastrodieae) in tropical Africa

SummaryThe holomycotrophic terrestrial orchids of tropical Africa are reassessed. Two new species of Gastrodia from tropical Africa are described, G. rwandensis from Rwanda and G. ballii from south-central Africa. The genus now comprises three species in tropical Africa. A key is provided to distinguish them from Gastrodia africana Kraenzl.

New species and records of Orchidaceae from São Tomé and Príncipe

Four new orchid species, Angraecopsis thomensis, Dinklageella scandens, Polystachya principia, and Stolzia thomensis from the islands of Sao Tome and Principe are described and illustrated.

New species and records of Orchidaceae from West Africa

A medium-sized terrestrial herb, up to 60 cm tall, with succulent brown roots. Leaves up to 9 clustered towards the base of the plant, ovate to obovate, acute to acuminate, 8 - 20 x 2.5 - 5 cm; petiole up to 6 cm long. Inflorescence erect, 20 - 50 cm long, laxly 10- to 30-flowered; peduncle glabrous, grooved, bearing 3 to 4 sterile bracts on lower half; bracts lanceolate, acuminate, 11 - 21 mm long. Flowers green, not much overtopping the bracts; pedicel and ovary 13- 15 mm long. Dorsal sepal cucullate, suberect, ovate, obtuse, 6 - 7.5 x 3.5 - 4 mm; lateral sepals deflexedrecurved, obliquely lanceolate, obtuse, 8 - 8.5 x 3.5 - 4 mm. Petals bifid just above base; posterior lobe adnate to the dorsal sepal forming a hood over the column, 6.5 - 7.5 x 1.5 mm; anterior lobe short, pointing downwards, 1 mm long. Lip rather fleshy, 3-lobed at base; side lobes upcurved , linear-falcate, rounded at apex, 6 x 0.7 mm; midlobe pendent, linear, rounded at apex, 7 x 0.8 mm; spur more or less parallel to the ovary, slightly decurved or S-shaped, 13- 15 mm long. Column 33.5 mm tall; stigmatic arms shortly clavate, 1.5 mm long. Fig. 1. Habenaria thomana is newly recorded from Cameroon, and for the Flora of West Tropical Africa region, having previously been considered endemic to the island of Siio Tome. The Cameroon specimens agree well with the type collection, differing only in the attitude of the spur which is usually slightly sigmoid, rather than slightly incurved, in the material examined. I append a description of H. thomana which should appear alongside that of its closest ally, Habenaria macrandra Lindl., in the Flora of West Tropical Africa orchid account (Summerhayes 1968).

New orchid discoveries in western Cameroon

Two new orchids from Cameroon, Polystachya kupensis P. J. Cribb & B. J. Pollard and Angraecum sanfordii P. J. Cribb & B. J. Pollard are described and illustrated. Polystachya stauroglossa Kraenzl. is newly reported from Cameroon. Notes on their distribution, habitat and conservation are provided.

Notes on Orchidaceae from the Pacific Islands

New combinations are made: Micropera draco (based on Sarcanthus draco), and Cystorchis ogurae (based on Hetaeria ogurae). The identities and distributions of Cleisostoma longipaniculatum and C. pacificum are clarified. A second collection of Cleisostoma porrigens (Fukuy.) Garay is reported from the Caroline Islands. Pelexia obliqua (J. J. Sm.) Garay is reported for Samoa; the relevant specimen had been named as Stereosandrajavanca Blume which should be deleted from that flora of Samoa. Vanilla hirsuta M. A. Clem. & D. L. Jones is reduced to synonymy in V tahitiensisJ. W. Moore.

A New Polystachya (Orchidaceae) from Sao Tome

The orchids of the island of Sio Tome in the Gulf of Guinea have been catalogued by Dandy & Summerhayes in Exell (1944), with additional records and novelties appearing in Exell (1956, 1959, 1973), Cribb (1996) and Cribb & la Croix (1997). Stevart (1998) has just completed an account of the orchids of the island and their ecology. During his recent botanical exploration work he has increased the known orchid flora from 64 to 98 taxa. Amongst these is an undescribed Polystachya which is here formally named and described. It has also been collected by A. Brune and flowered in the collection of one of the authors (la Croix).

Phaius tankervilleae and P. wallichii (Orchidaceae), a pair of confused species.

confusion over the years. Widespread and variable species often acquire names from various parts of their range that analysis of the entire variation can show to be synonyms or regional variants. A plant of Chinese origin was first flowered and named by Joseph Banks as Limodorum tankervilleae, a name subsequently validated by Aiton in 1757. Carl Blume transferred it to the present genus in 1856. Many authors followed Hooker (1894) in accepting a morphologically variable species for which he used the name P wallichii, with the earlier names Limodorum tankervilleae and Phaius grandiflorus in synonymy. Phaius wallichii was discovered in Sylhet by Nathaniel Wallich and was described by John Lindley in 1831. Most recent authors (Kataki 1986; Chowdhery 1998; Pearce & Cribb 2001) have followed Seidenfaden (1986) in recognising the priority of the name P tankervilleae. Seidenfaden recognised P tankervilleae as a morphologically variable species distributed from India and Sri Lanka to Taiwan, the Philippines, the Malaya Archipelago, SW Pacific and eastern Australia.

Five new taxa of Tridactyle (Orchidaceae) from West Central Africa

Five new taxa of Tridactyle are described and illustrated: T. exellii and T. thomensis from Sao Tome, T. aurantiopunctata from Principe, T. pentalobata from Gabon and T. anthomoniaca subsp. nana from Rio Muni in Equatorial Guinea. Maps of their distributions and notes on their habitat, cultivation and conservation are provided.

Plate 417. Calanthe izuinsularis

The taxonomy, relationships, distribution and cultural requirements of the Japanese Calanthe izuinsularis (Satomi) Ohwi & Satomi (Orchidaceae) are discussed; a colour illustration and dissection drawings are provided, together with a full description.