Tmesipteris horomaka, a new octoploid species from Banks Peninsula

Abstract

Tmesipteris horomaka sp. nov. is a rare octoploid, endemic to Banks Peninsula, New Zealand. It is morphologically intermediate between the tetraploids Tmesipteris elongata and Tmesipteris tannensis, and is possibly their allopolyploid derivative. DNA sequences from the trnLÁtrnF locus of the uniparentally inherited chloroplast support T. elongata as a progenitor, but direct evidence for T. tannensis is lacking. Tmesipteris horomaka differs from T. elongata in having predominantly emarginate to truncate leaf apices, and from T. tannensis in having synangia that are more rounded in shape, lacking or with only slight points that are directed laterally, rather than being clearly biconic with the points directed upwards away from the subtending leaf. Tmesipteris horomaka generally has bigger spores than both T. elongata and T. tannensis. We suggest that T. horomaka be treated in the Threat Classification System as Nationally Critical DP, OL , this being based on the small number of tree fern hosts on which it is currently known to grow.

A community‐derived classification for extant lycophytes and ferns

“…Circumscription sensu Kramer (). Monophyletic (Perrie et al, ). About 15 species. Order Ophioglossales Link, Hort.…”

Lastreopsis kermadecensis, a new fern species from Raoul Island in the Kermadec Islands, New Zealand, with notes onL. pacifica

“…pentangularis (Colenso) Tindale, which are also both tetraploids (Tindale & Roy 2002). An allo-tetraploid origin of L. kermadecensis would reinforce the taxonomic rank used here (Perrie et al 2003;Perrie et al 2010a); allopolyploidy can easily be overlooked using morphological consideration alone (Shepherd et al 2008). …”

A 160 Gbp fork fern genome shatters size record for eukaryotes

“…Tmesipteris (Psilotaceae) is a relatively understudied small genus made up of ∼15 species, 12 which are mainly epiphytic ferns occurring in Oceania and several Pacific Islands. Until now, the genome sizes of only two species had been reported in the genus, i.e., for the tetraploid T. tannensis (1C = 73.19 Gbp 13 ) and the octoploid T. obliqua (1C = 147.29 Gbp 9 ), both with giant genomes, and with the only two known ploidy levels reported for the genus (based on x = 52 14 ). The size of the genome of T. oblanceolata subsp.…”