RESUMEN
The complete chloroplast genome sequence of Haplopteris flexuosa, a member of Vittarioideae (family Pteridaceae), was determined. The chloroplast genome of H. flexuosa was 165,664 bp in length with two inverted repeats (32,556 bp) between a large single copy (79,996 bp) and a small single copy (20,556 bp). The GC content was higher than that of related taxa H. elongate, and it was caused by high GC content of expanded regions by insertion of mobile open reading frames in fern organelles (MORFFO) found in the family Pteridaceae. And also, we found that rrn5-rps12 enlarged region of H. flexuosa was similar to MORFFOs of other Pteridaceae.
RESUMEN
Although taxonomists target the remote wild regions to discover new species, taxa lacking a comprehensive and modern systematic treatment may be the new hotspot for biodiversity discovery. The development of molecular systematics integrated with microscopic observation techniques has greatly improved the ability of taxonomists to identify species correctly. Vittariacentrochinensis Ching ex J.F. Cheng, regarded as a synonym of Haplopterisfudzinoi (Makino) E.H.Crane, remained hidden from the eyes of fern taxonomists for more than 20 years. Herein, we collected several population samples of V.centrochinensis by performing molecular phylogenetic analysis of five cpDNA regions (rbcL, atpA, matK, ndhF, and trnL-trnF) and through micromophological observation of specimens which differs from H.fudzinoi by lamina width and exospores. Considering the differences in morphology, geographical range, and genetic distance between these two species, we formally recognized V.centrochinensis as an authentic species and proposed a new combination Haplopteriscentrochinensis (Ching ex J.F.Cheng) Y.H.Yan, Z.Y.Wei & X.C.Zhang, comb. nov. Our findings demonstrate that several taxa in synonyms are missing, and nowadays taxonomy should also include re-evaluation of the past taxonomy.
RESUMEN
Independent gametophyte ferns are unique among vascular plants because they are sporophyteless and reproduce asexually to maintain their populations in the gametophyte generation. Such ferns had been primarily discovered in temperate zone, and usually hypothesized with (sub)tropical origins and subsequent extinction of sporophyte due to climate change during glaciations. Presumably, independent fern gametophytes are unlikely to be distributed in tropics and subtropics because of relatively stable climates which are less affected by glaciations. Nonetheless, the current study presents cases of two independent gametophyte fern species in subtropic East Asia. In this study, we applied plastid DNA sequences (trnL-L-F and matK + ndhF + chlL datasets) and comprehensive sampling (~80%) of congeneric species for molecular identification and divergence time estimation of these independent fern gametophytes. The two independent gametophyte ferns were found belonging to genus Haplopteris (vittarioids, Pteridaceae) and no genetic identical sporophyte species in East Asia. For one species, divergence times between its populations imply recent oversea dispersal(s) by spores occurred during Pleistocene. By examining their ex situ and in situ fertility, prezygotic sterility was found in these two Haplopteris, in which gametangia were not or very seldom observed, and this prezygotic sterility might attribute to their lacks of functional sporophytes. Our field observation and survey on their habitats suggest microhabitat conditions might attribute to this prezygotic sterility. These findings point to consideration of whether recent climate change during the Pleistocene glaciation resulted in ecophysiological maladaptation of non-temperate independent gametophyte ferns. In addition, we provided a new definition to classify fern gametophyte independences at the population level. We expect that continued investigations into tropical and subtropical fern gametophyte floras will further illustrate the biogeographic significance of non-temperate fern gametophyte independence.