Similar to other plant groups, our understanding of grammitid ferns diversity of China has been steadily improved.
In a recent study published in PhytoKeys, researchers from Xishuangbanna Tropical Botanical Garden (XTBG) teste the hypothesis that conflicting species identity of the Chinese occurrences of Scleroglossum reflects the occurrence of two instead of one representative of this genus in mainland China.
The researchers studied living materials of the taxon collected from Hainan and Yunnan. They also compared existing herbarium specimens of known occurrences in Guangdong, Guangxi, Hainan, and Yunnan. Several herbarium collections of Scleroglossum from Vietnam were also checked carefully.
The comparisons were carried out to detect both phenotypic (morphology) and genotypic (DNA sequences) differentiation between the sampling accessions to recover evidence to support or reject the proposal of two species instead of a single species in mainland China.
Their integrative results show the Yunnan accessions are distinct from those in Hainan in both phenotypic and genotypic variation. The Yunnan accessions belong to S. pusillum, whereas the Hainan accessions represent a distinct species displaying the morphological characteristics of S. sulcatum. Genotypic evidence suggests the occurrence of cryptic diversity among accessions with the morphology of S. sulcatum.
The assessment and conservation of these local rare species is challenging but the usage of DNA barcoding approaches may enable reliable surveys that do not require the involvement of the few taxonomic experts. In turn, these assessments may also provide crucial information to improve existing taxonomic treatments by providing evidence to test taxonomic concepts that may be challenged by the occurrence of cryptic species.