- Gujarat-based scientists discovered a thumbnail-sized fern in a village in Dang district in Gujarat, in the northern-most part of the Western Ghats.
- The scientists called it the world’s smallest terrestrial fern and have named it Ophioglossum malviae.
- Other pteridologists (ferns specialists) do not agree with the plant’s distinction as the world’s smallest terrestrial fern and point to flaws in the study.
- Today, May 22, is the International Day for Biological Diversity and 2018 marks 25 years of celebrating action for biodiversity.
A Gujarat-based scientist duo from the Bapalal Vaidya Botanical Research Centre of the Veer Narmad South Gujarat University, have found a very small fern— just about the size of a thumbnail— in the northernmost part of the Western Ghats. The fern was first spotted by Mitesh Patel, a PhD student at the university, during his annual field trip to the village of Jakhana to collect samples of Ophioglossum, a fern he is trying to understand better through his research. The small fern he found looked unmistakably like a member of the Ophioglossum genus, but of a very small size.
Back in the laboratory, Patel and his PhD supervisor Mandadi Narsimha Reddy got to work to find the accurate identity of this tiny fern. They studied its DNA sequence and compared it to the DNA sequences of other known varieties of Ophioglossum. They also compared its size, other morphological features and its spore structure to that of known varieties. The comparisons led the duo to the conclusion that Patel’s tiny find was a hitherto unknown species of fern and that it is the tiniest terrestrial fern ever. The new species was named Ophioglossum malviae and the findings were published in the journal Scientific Reports recently.
Ophioglossums have been attracting pteridologists for a long time, because of their unique identity as the organism with highest number of chromosomes. Varieties with up to 1440 chromosomes have been reported so far, when comparatively more evolved organisms like humans have only 46 chromosomes. It was this distinctive identity of Ophioglossums that attracted Patel to study the fern species.
Though the team is still working on finding the chromosome number of Ophioglossum malviae, they have used its DNA sequence to estimate its evolutionary relatedness to other species of Ophioglossum. They have created a phylogenetic tree − a diagram that clusters together closely-related species and scatters away the ones that are less related. Their phylogenetic tree shows that O.malviae is closely related to O. nudicale and O. parvifolium, both of which are found in India.
Not really a new species?
However, not all pteridologists are convinced with the phylogenetic tree furnished by the authors and have raised a red flag. Ajit Pratap Singh, head of the Pteridology Division of the National Botanical Research Institute (CSIR-NBRI) said that the “phylogenetic dendrogram based on DNA data is not convincing as the percentage of maximum likelihood analysis achieved is not sufficient to treat O. malviae as a new species.” He also said that, “O. gramienum is already reported to be smaller than O. malviae and that the newly found O. malviae could just be a stunted version of a common species O. nudicaule growing under xeric conditions and not really a new species.” Singh points to two major flaws in the study, one, that the authors did not adequately “consult previous publications about the length of the ferns and second, they did not widely compare the morphological characteristics of their specimen with that of O. nudicaule and other allied species of Ophioglossum deposited in Indian or international herbaria.
Another pteridologist, B. S. Kholia, scientist at the Botanical Survey of India, Dehradun, called the claims made by the paper, “inflated.” He said that “the researchers have failed to make any molecular or morphological comparison with the genuinely relevant taxa with similar rhizome, like, O. raphaelianum and O. oleosum.”
“Though I am not rejecting the name O. malviae, I strongly feel it needs better justification and a comparison with small-sized species with similar rhizome, like O. oleosum and O. raphaelianum,” he added.
Concerns were also raised by the director of Blatter Herbarium, St. Xavier’s College, Mumbai, where the authors have submitted their plant samples. It is mandatory for researchers to submit their plant samples in a herbarium before they can publish their findings.
Rajendra Shinde, the Director of Blatter Herbarium, said that though the methods used by the authors to confirm the identity of the plant are “acceptable and correct”, the manner in which the samples were submitted at the Blatter Herbarium are questionable. The authors failed to inform the herbarium officials that the samples belong to a new species. They also did not provide any information on “type” of the plant. “Type is a must. A plant without a type is a like a person without any ID”, said Shinde.
Misidentification common among Indian pteridologists
A Current Science article, in 2011, by Kholia and C. R. Fraser-Jenkins of the department of botany, The Natural History Museum in London has also cited several examples of misidentification of ferns by Indian researchers. The study says, “Misidentification of fern species, often accompanied by comments on the supposedly interesting phytogeographical disjunction, or of a ‘first report’ from an area, are legion in Indian pteridology, again compounded by the lack of study in herbaria and failure to identify specimens properly, or to consult others who would be able to do so.”
In this case, however, one must keep in mind that the paper was published after peer review, so, clearly, there are scientists who agree with O. malviae’s distinction as the smallest new terrestrial fern. At the same time, it will be correct to say that the scientists are divided in their opinion on O. malviae’s status as a new species.
Meanwhile, Patel says, he has found several species of Ophioglossum from the same phyto-geographical area that could potentially be unknown to the world yet. He is working on determining their identities.