A genus of about 30 species with only one occurring in Australia. These leafless epiphytic orchids have flat, spreading roots that are appressed to the host. The short stemed raceme, 50-flowered, increase in length as they flower. The small tubular flowers are 0.1 cm wide, pale green in colour, last 3-5 days and open progressively along the inflorescene. The sepals and petals are fleshy and spreading. The petals are fused to the sepals. The sepals are similar in size and shape while the petals are slightly smaller than the sepals. The labellum is triangular in shape, has a sharply recurved apex which ends in a filiform appendage. Microtatorchis flowers from May to October and occur in Queensland.
Similar Genera
Significant Generic Characters
This species has single plants that do not form clonal colonies. They are leafless, have flat roots and racemes consisting of a short filiform peduncle and a fleshy, zigzagged, rhachis about twice as thick, with 2 rows of protruding deltate bracts, small pale green tubular flowers with the sepals and petals fused in the proximal third, and a triangular labellum with the apex sharply recurved and ending in a filiform appendage about 0.5 mm long.
Size and Distribution
A genus of of about 30 species, most from New Guinea, but also New Caledonia, Indonesia, Philippines, Samoa and Australia where there is a single species. Microtatorchis clementsii is known from Mt Windsor Tableland, Henrietta Creek (photograph only) and Paluma in northeastern Queensland; 1000-1250 m alt. State occurance: Queensland.
Ecology
Microtatorchis clementsii grows on the branches of trees in highland rainforest.
Biology
Pollination: The flowers of Microtatorchis clementsii last 3-5 days and are produced in succession over many months. They appear to be insect-pollinated.
Flowering: Microtatorchis clementsii flowers from May to October.
Derivation
Named after Mark Alwin Clements (1949-), specialist in the family Orchidaceae who has recently published the results of detailed phylogenetic studies into the Dendrobium alliance.
Botanical Description
Leafless epiphytic herb. Plants single. Roots appressed to the host, spreading, flat in cross-section, 20-40 mm long, c. 1 mm across, green. Stems c. 1 mm long, unbranched. Racemes 10-30 mm long, flowering progressively and increasing in length; peduncle filiform, hairless; rhachis twice as thick as the peduncle, fleshy, dumbbell-shaped in cross-section, flexuose, 5-c. 50-flowered. Fertile bracts in 2 ranks, at right angles to the rhachis, deltate, c. 0.7 mm long, c. 0.7 mm wide. Flowers opening singly, tubular, c. 1.3-1.5 mm long, c. 1 mm across, pale green; buds, open flowers and capsules can be present simultaneously. Sepals and petals fleshy, spreading only in the distal half. Dorsal sepal porrect in the proximal third then obliquely erect, ovate, c. 1.2 mm long, c. 0.6 mm wide, obtuse. Lateral sepals porrect to narrowly divergent, c. 1.6 mm long, c. 0.6 mm wide, obtuse. Petals fused proximally to the sepals, sagittate, c. 1 mm long, c. 0.6 mm wide, obtuse to subacute. Labellum porrect, concave, narrowly deltate when flattened, c. 1 mm long, c. 0.5 mm wide; apex recurved at right angles, with a filiform appendage c. 0.5 mm long; spur continuous with the lamina, globose, c. 0.6 mm long. Column c. 0.75 mm long, c. 0.5 mm wide. Anther ovate, c. 0.4 mm long, 0.4 mm wide. Pollinarium c. 0.5 mm long. Pollinia 2, c. 0.3 mm long. Stipe linear, c. 0.25 mm long. Viscidium small. Stigma c. 0.4 mm across, sunken. Capsules not seen.
Notes
Some species of Microtatorchis have leaves when they are juvenile plants and these appear to be shed as the plants reach maturity and begin flowering. There was no sign of any leaves on the Microtatorchis clementsii and protocorms and juvenile plants were also leafless. Schlechter (1982) notes that these orchids often grow near the tips of young branches and he considers them to be fast growing with some species flowering when less than one year old. They may act as pioneering plants colonising fallen trees in areas of disturbance, as caused by storms and cyclones, as well as trees in open sites, persisting in living trees along rainforest margins and road verges.
Microtatorchis clementsii appears to share some similarities with M. platyrhachis Schltr. from the Dischore Range in New Guinea (Schlechter 1982), but has smaller flowers with ovate rather than oblong sepals, sagittate rather than ovate petals and a deltate rather than ovate-lanceolate labellum with a sharply upturned apex ending in an erect filiform lobe c. 0.5 mm long.
Microtatorchis is distinguished by its two pollinia, whereas species of Taeniophyllum have four.
Nomenclature
Microtatorchis Schltr. in K.Schum. et Laut., Nachtr. Fl. Deutsch. Schutzgeb. Südsee 224 (Nov.1905). Lectotype species: Microtatorchis perpusilla Schltr., vide A.A.Bullock, ING card 05211 (30 Mar.1958).
References
Jones, D.L. & Gray, B. (2006). Microtatorchis clementsii (Orchidaceae), a new generic record and new species from Australia. Orchadian 15(5): 200-202.
Schlechter, R. (1911). Revision der Orchidaceen von Deutsch-Samoa. Repert. Spec. Nov. Regni Veg. 9: 112.
Schlechter, R. (1982). The Orchidaceae of German New Guinea (English translation by R.S. Rogers, H.J. Katz and J.T. Simmons). Australian Orchid Foundation, Melbourne.