Biodiv Sci ›› 2019, Vol. 27 ›› Issue (11): 1205-1220.DOI: 10.17520/biods.2019316

• Original Papers • Previous Articles     Next Articles

Integrative taxonomy resolved species delimitation in a fern complex: A case study of the Asplenium coenobiale complex

Siqi Liang1,2,Xianchun Zhang1,Ran Wei1,*()   

  1. 1 State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany, Chinese Academy of Sciences, Beijing 100093
    2 University of Chinese Academy of Sciences, Beijing 100049
  • Received:2019-10-09 Accepted:2019-12-17 Online:2019-11-20 Published:2020-01-17
  • Contact: Wei Ran

Abstract:

Due to wide hybridization and polyploidization, there are numerous species complexes with taxonomic challenges in the fern genus Asplenium. Integrative taxonomy using evidence of morphology, cytology and molecular phylogeny provides one of the best ways for the discovery and delimitation of species. The Asplenium coenobiale complex represents one of the spleenwort complexes, which are morphologically variable and difficult in species delimitation. Owing to the lack of comprehensive sampling and systematic study, the taxonomy of this complex remains unresolved. In this study, we selected representative individuals of this complex covering differences in morphology and geography. We conducted a palynological study to explore reproductive characteristics, and inferred the ploidy level through flow cytometry. Furthermore, based on the phylogenetic evidence from chloroplast and nuclear genomes, we discussed the evolutionary relationship and origin of this complex. Our results showed that: (1) The development of 64 spores within a single normal sporangium is indicative of the ability of sexual reproduction, although abortive sporangia are common in the Asplenium coenobiale complex. (2) Ploidy variation is found in this complex, i.e. A. cornutissimum is diploid, whereas other members are all tetraploid. (3) The maternally inherited chloroplast phylogeny supported four clades within this complex, and this was incongruent with the nuclear phylogeny; therefore, it was inferred that hybridization could be an important driving force during the formation of the complex. Based on our analyses, we conduct a revision to the A. coenobiale complex, i.e. one newly discovered autotetraploid species (A. maguanense sp. nov.), one diploid species (A. cornutissimum), and two allotetraploids with reciprocal origins (A. coenobiale and A. pulcherrimum).

Key words: chloroplast sequences, pgiC, Asplenium coenobiale complex, hybridization, polyploidy