Rhipidoglossum pareense is endemic to the South Pare and West Usambara mountains of north-eastern Tanzania.
“Rhipidoglossum pareense belongs to a small group of species previously assigned to the genus Margelliantha and is distinguished by its dwarf habit, short stem and short inflorescence of few campanulate flowers,” said University of Bayreuth’s Dr. Andreas Hemp and Dr. Phil Cribb from the Royal Botanical Gardens, Kew.
“The East African species of Margelliantha have recently been subsumed in a broadly defined Rhipidoglossum based upon extensive DNA analysis.”
The most striking feature of Rhipidoglossum pareense, which is only a few centimeters tall, is its white flowers.
If the orchid is held against the sunlight, the flowers appear to glisten.
Its flowers are smaller but more numerous than those of the closest related species, Rhipidoglossum leedalii.
The inflorescence is much more compact and resembles that of a lily of the valley.
Rhipidoglossum pareense occurs the South Pare and West Usambara mountains as an epiphyte in montane, low-stature cloud forests at an altitude above 1,500 m.
The trees there only reach a height of 10 m and are densely covered with mosses, ferns and orchids.
According to the researchers, Rhipidoglossum pareense probably owes its existence to the very unusual climatic conditions.
“The climate of the type locality in the Pare Mountains is humid and foggy,” they explained.
“Mean annual rainfall is only about 1,000 mm, however fog water interception provides more than twice of this amount in addition. Consequently, mean annual relative humidity is 94%.”
“Mean annual temperature is 15.7 degrees Celsius with a minimum temperature of 8.7 degrees Celsius and a maximum temperature of 29 degrees Celsius.”
“Because of this high humidity, tree trunks and branches are densely covered by mosses (60% coverage) and vascular epiphytes (10% coverage).”
The discovery is reported in a paper in the journal Kew Bulletin.
P.J. Cribb & A. Hemp. Rhipidoglossum pareense (Orchidaceae: Epidendroideae), a new species from Tanzania. Kew Bull, published online July 29, 2022; doi: 10.1007/s12225-022-10027-2
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