Search

A new species of Ophioglossum, O. isanense, from Northeast Thailand is described and illustrated. It may be diagnosed from other congeners by a combination of morphological characters including: its smaller size, cylindrical rhizome, stoloniferous roots, brownish green common stalk and trophophylls, the presence of persistent leaf sheath at the top of the rhizome and by the unique structure of spores. Molecular study also supported it as a distinct species. A summary of the ecology and an IUCN conservation status of the new species are provided.

Limpanasittichai P, Jaruwattanaphan T. 2022. Chromosome number and reproductive mode of some Pteris species (Pteridaceae) in Thailand. Biodiversitas 23: 3285-3296. The fern genus Pteris L. (Pteridaceae) consists of 329 species. This genus is one of the largest fern genera and is quite diverse with many different ploidy levels and reproductive modes resulting from complicated hybrid speciation events in their evolution. However, there have been very few observations of Pteridophytes in Thailand. This study aims to investigate chromosome number and reproductive mode of Pteris in Thailand. Mitotic chromosome numbers of 9 species collected from natural habitats were observed by hematoxylin squash method and their reproductive modes were estimated by counting the number of spores per sporangium. Three cytotypes were found, namely diploid, triploid and tetraploid. Nevertheless, only sexual individuals were recognized. First reports are provided for 3 species, namely P. dalhousieae (2n = 2x = 58, sexual), P. decrescens (2n = 2x = 58, sexual), and P. heteromorpha (2n = 2x = 58; 2n = 3x = 87 and 2n = 4x = 116, sexual) and the chromosome numbers from the remaining taxa match those reported from other countries. Two species, namely P. heteromorpha and P. vittata exhibited diverse cytotypes.

Polyploidy, hybridization, and agamospory have been considered important mechanisms in fern speciation. By integrating the methods of cytology, molecular phylogeny, and morphology, we examined the origins of polyploid species in the Pteris cretica group, which comprises five agamosporous taxa and six sexual species. Phylogenetic analysis was conducted using both cpDNA (rbcL and trnV-trnM) and a low-copy nuclear gene (gapCp). The combined results of cytology and the phylogenetic trees suggested that the sexual diploid P. kidoi had played a central role in the diversification of polyploid species in the P. cretica group. Some triploid clones of agamosporous P. cretica var. cretica originated through hybridization between the diploid cytotype of P. cretica var. cretica and the sexual diploid P. kidoi. The sexual polyploid species, P. henryi, P. multifida, P. ryukyuensis, and P. yamatensis, and the hexaploid race of P. deltodon have arisen through allopolyploidization between their respective ancestr...

An Asia-Pacific fern species Pteris terminalis , formerly known as ‘ Pteris excelsa’ is variable in terms of frond morphology as well as cytological characters. In particular, the results of previous cytological studies raised question on naturalness of currently accepted infraspecific taxa—‘ P . excelsa var. simplicior’ (not yet combined with P . terminalis ) consists of apogamous diploid and triploid, but these cytotypes are shared by the typical form of ‘ P . excelsa’ (= P . terminalis ), which is most widely distributed as sexual diploid. In the present study, the two varieties are re-circumscribed chiefly based on reproductive modes. Morphological characters including the length of apical pinna segments and the dissection degree of acroscopic side of pinna often, but not always, help their identification. After examination and lectotypification of type specimens of related taxa, correct names at varietal rank, two varieties P. terminalis var. terminalis and P. terminalis var. fauriei are proposed for the sexual form and the apogamous form, respectively.