Abstract
Here we report the rediscovery of four endemic gesneriads from the state of Mizoram, India, after a span of 86 to 90 years since their last collection. The four species belong to the genus Didymocarpus Wall. and they are: D. adenocarpus, D. lineicapsa, D. parryorum, and D. wengeri. We present revised morphological descriptions, photographs, and designate lectotypes for D. parryorum and D. wengeri. During our study we came across several discrepancies between morphological characters assigned to these four species in the protologue and morphological characters present (or absent) in the type specimens and in plants recollected by us. We list these discrepancies in a section titled ‘amendments to protologue’. Based on the high endemicity and critical conservation status of all the four rediscovered species, we suggest that floristic studies along with large-scale biogeographic studies should be prioritized in the Indo-Burmese region.
Highlights
The genus Didymocarpus Wall. was recently redefined by Weber and Burtt (1998) and it consists of approximately 100 species that are distributed in India, Nepal, Bhutan, southern China, Myanmar, Thailand, Vietnam, Laos, Cambodia, Peninsular Malaysia, Copyright N.S
Our observations suggest that all four species are narrow endemics within the state of Mizoram, India, which was noted by earlier botanists like Wenger (Fischer 1928a) in the type description (Fig. 1)
We evaluated the conservation status for the four rediscovered species according to the latest International Union for Conservation of Nature guidelines (IUCN 2019) using species distribution ranges and size of the populations we encountered during fieldwork
Summary
The genus Didymocarpus Wall. was recently redefined by Weber and Burtt (1998) and it consists of approximately 100 species that are distributed in India, Nepal, Bhutan, southern China, Myanmar, Thailand, Vietnam, Laos, Cambodia, Peninsular Malaysia, Copyright N.S. Phylogenetic studies by Palee et al (2006) suggested the geographic origin of the genus to be Malay Peninsula, the northeast region of India along with southern China accounts for more than half of known Didymocarpus species (Möller et al 2017; Möller 2019). All four gesneriads reported here have not been collected since either Parry or Wenger collected them in the early 1900s, despite recent revisionary, taxonomic, or floristic studies carried out in the Northeast of India (Sinha 2012; Sinha and Datta 2016; Roy 2017). The rediscovery of the four Didymocarpus species is an outcome of our concerted effort to collect gesneriads from the Northeast of India for our ongoing revision of the genus using a molecular phylogenetic approach. We assign lectotypes for both these species here
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