Introduction

The genus Microchirita (C.B.Clarke) Yin Z.Wang in the Gesneriaceae, subfamily Didymocarpoideae, is a genus of about 36 species from India, Myanmar, southern China, Thailand, Vietnam, Laos, Cambodia, Peninsular Malaysia, Sumatra, Java and Borneo, almost exclusively in limestone habitats (Puglisi & Middleton, Reference Puglisi and Middleton2017). Microchirita was formerly included as a section of Chirita Buch.-Ham. (Wood, Reference Wood1974) but was raised to generic rank by Wang et al. (Reference Wang, Mao, Liu, Li, Dong, Li and Smith2011) when Chirita was found to be polyphyletic (see Weber et al., Reference Weber, Middleton, Forrest, Kiew, Lim, Rafidah, Sontag, Triboun, Wei, Yao and Möller2011). The centre of diversity of Microchirita is in Thailand (Puglisi & Middleton, Reference Puglisi and Middleton2017), although the genus has been much less well studied elsewhere and it is likely there are many more species to be described, particularly from Laos and Vietnam.

There is relatively little variation in vegetative characters in the genus but considerable variation in the structure of the inflorescence and in flower characters, most noticeably in the size, shape and colour of the corolla. Flower colour is generally lost in herbarium material and many species appear rather similar from herbarium specimens that lack good collection data. Useful characters in the anthers and ovary are usually observable only when the flowers are dissected. Wood (Reference Wood1974) included all specimens with small white flowers in a broadly circumscribed Chirita hamosa R.Br. but noted that this species was “confusingly variable”. Middleton & Triboun (Reference Middleton and Triboun2013), who saw more collections and carried out fieldwork to observe differences in corolla shape and colour in living plants, split Microchirita hamosa (R.Br.) Yin Z.Wang into several species that all had small white flowers but differed consistently in other morphological characters. Subsequently, Middleton & Puglisi (Reference Middleton and Puglisi2015) discussed problems in application of the name Chirita/Microchirita hamosa and proposed to conserve the name with a new type. This was supported by the Nomenclature Committee for Vascular Plants (Applequist, Reference Applequist2016) and ratified at the 2017 International Botanical Congress.

The work of Middleton & Triboun (Reference Middleton and Triboun2013) and Puglisi & Middleton (Reference Puglisi and Middleton2017) primarily concerned the clarification of species limits in the genus in Thailand. Rafidah (Reference Rafidah2017) revised the genus in Malaysia. In other parts of its distribution, however, Microchirita remains rather poorly known. Möller et al. (Reference Möller, Nampy, Janeesha and Weber2017) suggested that there were two species of Microchirita in India. These were not listed, but photographs of Microchirita hamosa were included. Puglisi & Middleton (Reference Puglisi and Middleton2017) noted that the ranges of three species found in Thailand, Microchirita albiflora D.J.Middleton & Triboun, M. bimaculata (D.Wood) A.Weber & D.J.Middleton and M. hamosa (R.Br.) Yin Z.Wang, also included India, making four species in total with the Indian endemic M. sahyadriensis (Punekar & Lakshmin.) A.Weber & D.J.Middleton.

Wood (Reference Wood1974) listed only one species that is now included in Microchirita from India, Chirita hamosa, but did include a number of names in synonymy. Most of these synonyms are indeed Microchirita hamosa, but one, Didymocarpus cristatus Dalzell, is not this species if one extends the species concepts adopted by Middleton & Triboun (Reference Middleton and Triboun2013), Puglisi et al. (Reference Puglisi, Middleton and Suddee2016) and Puglisi & Middleton (Reference Puglisi and Middleton2017). Burtt (Reference Burtt1960) had also suggested that this was not the same as Chirita hamosa and made the combination Chirita cristata (Dalzell) B.L.Burtt.

The type of Didymocarpus cristata is a fruiting collection by Dalzell from Parwarghat (= Parva Ghat) in the south of Maharashtra State. It has only remnant corollas, but these have only very few hairs on the outside, unlike the corollas of Microchirita hamosa, which are much more densely pubescent. The corollas are too shrivelled to tell if they are straight as in Microchirita hamosa or more curved as in most species in the genus. The corolla appears to be about 1 cm long, similar to that of Microchirita hamosa. The fruit is much less pubescent than in Microchirita hamosa, and generally curved when mature, unlike the straight fruit of M. hamosa. The crested inflorescence is also much larger and with more flowers than in Microchirita hamosa. There is no corolla colour data on the label of the specimen, but Dalzell (Reference Dalzell1851) says the corolla is white, the same as for Microchirita hamosa.

With only a rather poor type collection and a few other fruiting specimens available, it remains rather unclear what Didymocarpus cristatus actually is, except that it is not Microchirita hamosa. It is from the Western Ghats of India, where only one other species is recorded, the white-flowered Microchirita sahyadriensis. As the type localities of the two species are within 80 km of each other, it is possible that these two are the same species, in which case Didymocarpus cristatus has priority. Flowering material from the type locality of Didymocarpus cristatus is needed to ascertain this. Whether they are one species or two, there is currently no combination in Microchirita for Didymocarpus cristatus. The combination is made here.