Chromosome Numbers of Hawaiian Angiosperms: New Records and Comments

Abstract

In this paper chromosome counts for 90 collections representing 67 native Hawaiian angiosperm species and eight hybrids in 22 families are presented and discussed. Included are the first records for 26 species, two subspecific taxa, eight natural hybrids, and the endemic genus Pteralyxia (Apocynaceae). In four families Hawaiian representatives have been investigated cytologically for the first time. For three species the investigations are the first on Hawaiian material. Seven counts differ from earlier reports in the literature. Implications of the results are discussed in the context of autochthonous chromosomal evolution and of colonization events for the Hawaiian Islands.

Pittosporum halophilum Rock (Pittosporaceae: Apiales): Rediscovery, Taxonomic Assessment, and Conservation Status of a Critically Endangered Endemic Species from Moloka'i, Hawaiian Islands

“…), 2n = 24 was established as the chromosome number of P. halophilum, based on investigations of a plant growing at the nursery of the NTBG (MK0901151/4, wu). This number deviates from counts for two unidentified Hawaiian Pittosporum species (2n = 34 -36 [Kiehn 2005]) but is in accord with counts for six other Hawaiian Pittosporum species (P. glabrum Hook. & Arnott [Carr 1978], P. gayanum [Kiehn 2005], and P. hosmeri Rock, P. kauaiensis Hillebr., P. napaliense, P. terminalioides [M.K., unpubl.]).…”

“…This number deviates from counts for two unidentified Hawaiian Pittosporum species (2n = 34 -36 [Kiehn 2005]) but is in accord with counts for six other Hawaiian Pittosporum species (P. glabrum Hook. & Arnott [Carr 1978], P. gayanum [Kiehn 2005], and P. hosmeri Rock, P. kauaiensis Hillebr., P. napaliense, P. terminalioides [M.K., unpubl.]). Chromosomes are subtelocentric to telocentric, 6 -9 μm long in mitotic ( pro)metaphase, and are indistinguishable from those of other Pittosporum species cytologically investigated to date (M.K., unpubl.).…”

“…Specimens from both herbaria were used for comparative studies between P. halophilum and other Hawaiian Pittosporum. Chromosome data were obtained using the techniques described in Kiehn (2005), from apex tissue of a plant cultivated at the NTBG (acc. no.…”

“…chromosome number: In the course of ongoing studies of chromosome numbers in Hawaiian Pittosporum (Kiehn 2005; M.K., unpubl. ), 2n = 24 was established as the chromosome number of P. halophilum, based on investigations of a plant growing at the nursery of the NTBG (MK0901151/4, wu).…”

Diversification of HawaiianCyrtandra(Gesneriaceae) under the influence of incomplete lineage sorting and hybridization

“…Based on the highly similar habitats (tropical forest understory) across the broad geographic region occupied by the genus, Cyrtandra is likely to have diverged under a dispersal‐mediated allopatry model rather than ecological pressures (Cronk et al, ; Clark et al, ). To date, all examined species of Cyrtandra are diploid (Kiehn, ) and there is no evidence of polyploidy in the group. Prior phylogenetic studies support monophyly of the Pacific clade, suggesting that the ~300 species within this clade diversified within the last 22 million years (Clark et al, ; Johnson et al, ).…”