4 
Card. Bull. Singapore 69(1) 2017 
and Pahang, and also from direct human disturbance. 
Microchirita species are not economically valuable but rather have value as 
flagship species of threatened limestone habitats because they are found nowhere 
else. Table 1 summarises the conservation status of each species of Microchirita in 
Malaysia. Two taxa are categorised as Teast Concern (LC), one as Near Threatened 
(NT), one as Vulnerable (VU) and two as Endangered (EN). None of the Microchirita 
species in Malaysia are categorised as Extinct (EX). The two taxa that are categorised 
as LC occur within the network of Totally Protected Areas (in Taman Negara) and 
have no known current threats. Of the three threatened taxa, the two Endangered 
taxa, Microchirita ruthiae (found only in Kelantan) and M. sericea (found only in 
Perak, Perlis and Kedah), are endemic to Peninsular Malaysia and the hills where 
they grow are not legally protected and are threatened by quarrying. The Vulnerable 
taxon, Microchirita rupestris (Ridl.) A.Weber & Rafidah, is categorised as Vulnerable 
in Malaysia whereas globally it should be considered Least Concern (Middleton, pers. 
comm.). Further details are under each species. 
Table 1. Conservation status of Microchirita species in Peninsular Malaysia. 
Species 
No. of hills 
IUCN Category 
Microchirita caliginosa (C.B.Clarke) Yin Z.Wang 
24 
Least Concern 
Microchirita involucrata (Craib) Yin Z.Wang 
18 
Least Concern 
Microchirita rupestris (Ridl.) A.Weber & Rafidah 
7 
Vulnerable 
Microchirita ruthiae Rafidah 
6 
Endangered 
Microchirita sericea (Ridl.) A.Weber & Rafidah 
5 
Endangered 
Microchirita viola (Ridl.) A.Weber & Rafidah 
6 
Near Threatened 
Notes on selected habitat and morphological characters 
In Peninsular Malaysia, as elsewhere, Microchirita species are morphologically very 
similar, especially when sterile. Nevertheless, there are a few characters that separate 
the species even though vegetative and reproductive characters can be variable. 
Observations in the field, together with photos, are important in recording diagnostic 
characters that cannot be seen or are difficult to see in dried herbarium specimens. 
Microchirita caliginosa (C.B.Clarke) Yin Z.Wang and M. involucrata (Craib) 
Yin Z.Wang are frequently found at the base of hills where there is a thin soil layer. 
On this soil Microchirita caliginosa and M. involucrata always produce carpets 
of seedlings that grow rapidly. Microchirita sericea, M. rupestris, M. viola (Ridl.) 
A.Weber & Rafidah and M. ruthiae, however, inhabit rock crevices and cracks in 
the limestone, sometimes in wet conditions. Microchirita species often have a short 
lifespan or are annual with most species living for less than six months to one year 
(pers. obs.). What would appear to be perennial plants have been observed, however, 
