''Myosotis pansa'' subsp. ''praeceps'' is a subspecies of flowering plant in the family Boraginaceae, endemic to the

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of New Zealand. Lucy Moore described the variety ''M. petiolata'' var. ''pansa'' in 1961, and it was transferred to a subspecies of '' M. pansa'' by Heidi Meudt, Jessica Prebble, Rebecca Stanley and Michael Thorsen in 2013. Plants of this species of forget-me-not are perennial rosettes with partially bracteate inflorescences and white corollas with exserted stamens.

Taxonomy and etymology

''Myosotis pansa'' subsp. ''praeceps'' is in the plant family Boraginaceae. The subspecies was originally described as a variety of ''

Myosotis petiolata ''Myosotis petiolata'' is a species of flowering plant in the family Boraginaceae, endemic to the Hawkes Bay region of the North Island of New Zealand. Joseph Dalton Hooker described the species in 1853. Plants of this species of forget-me-n ...

'' in 1961 by Lucy Moore. The plant and others in the genus of Myosotis are colloquially known as forget-me-nots. Plants in the genus are also referred to as Scorpion grass. It was transferred to subspecies rank under ''Myosotis pansa'' by (L.B.Moore) Meudt, Prebble, R.J.Stanley and Thorsen in 2013. The holotype specimen of ''Myosotis pansa'' subsp. ''praeceps'' was collected by Anthony P. Druce in 1972 at Waikawau Beach, and is lodged at the Allan Herbarium of

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(CHR 208886). The subspecies epithet, ''praeceps'', is a Latin word with two relevant meanings: ' precipice' (referring to its habitat), and 'danger' (referring to its threatened status). Based on morphological and genotyping evidence, this is one of two subspecies recognised in '' M. pansa''; the other is ''M. pansa'' subsp. ''pansa''. The subspecies are largely

allopatric Allopatric speciation () – also referred to as geographic speciation, vicariant speciation, or its earlier name the dumbbell model – is a mode of speciation that occurs when biological populations become geographically isolated from ...

, as ''M. pansa'' subsp. ''praeceps'' is found in coastal areas of Waikato and northern Taranaki on the North Island, whereas ''M. pansa'' subsp. ''pansa'' is found in the Auckland region. In subsp. ''praeceps'' the inflorescences are partially bracteate (i.e. there are cauline leaves associated with the lowest 1–3 or up to 9 flowers, whereas in subsp. ''pansa'', the inflorescences are ebracteate (i.e. none of the flowers have associated cauline leaves).

Phylogeny

''Myosotis pansa'' subsp. ''praeceps'' was shown to be a part of the

monophyletic In cladistics for a group of organisms, monophyly is the condition of being a clade—that is, a group of taxa composed only of a common ancestor (or more precisely an ancestral population) and all of its lineal descendants. Monophyletic gro ...

southern hemisphere lineage of ''Myosotis'' in phylogenetic analyses of standard DNA sequencing markers (

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and chloroplast DNA regions). Within the southern hemisphere lineage, species relationships were not well resolved. Multiple individuals ''Myosotis pansa'' subsp. ''praeceps'' were included in two studies that phylogenetically analysed amplified fragment length polymorphisms (AFLPs). In these analyses, ''Myosotis pansa'' subsp. ''praeceps'' was genetically differentiated from ''M. pansa'' subsp. ''pansa,'' as well as from other related species, '' M. petiolata'' and '' M. pottsiana''. SP089686_Myosotis_pansa_subsp

Description

''Myosotis pansa'' plants are rosettes. The rosette leaves have petioles that are 4 to 67 mm long. The rosette leaf blades are 5 to 60 mm long by 4 to 31 mm wide (with a length-to-width ratio of 1.1:1 to 2.1:1), usually narrowly obovate, obovate, broadly obovate, widest at or above the middle, with an obtuse and

retuse The following is a list of terms which are used to describe leaf morphology in the description and taxonomy of plants. Leaves may be simple (a single leaf blade or lamina) or compound (with several leaflets). The edge of the leaf may be regular o ...

apex. The upper surface of the leaf is uniformly or patchily covered in straight, appressed, antrorse (forward-facing) hairs. The lower surface of the leaf is glabrous. Each rosette has multiple ascending, once-branched or rarely unbranched partially bracteate inflorescences that are up to 490 mm long. The cauline leaves are similar to the rosette leaves, but become smaller. The flowers are 3 to 95 per inflorescence and each is borne on a short

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with or without a bract. The calyx is 2 to 4 mm long at flowering and 3 to 9 mm long at fruiting, lobed to half to most of its length, and sparsely to densely covered in straight to curved, appressed to patent, antrorse hairs. The corolla is white and 4 to 11 mm in diameter, with a cylindrical tube, petals that are usually obovate, broadly obovate or very broadly obovate, and small yellow scales alternating with the petals. The anthers are fully exserted. The four smooth, shiny, usually dark brown nutlets are 1.4 to 2.1 mm long by 1.0 to 1.4 mm wide, and ovoid to broadly ovoid in shape. Published studies of the pollen and chromosome numbers of several species of ''Myosotis'' did not include ''Myosotis pansa'' subsp. ''praeceps''.

Distribution and habitat

''Myosotis pansa'' subsp. ''praeceps'' is endemic to the North Island of New Zealand in the Auckland region, from sea level to

above sea level Height above mean sea level is a measure of the vertical distance (height, elevation or altitude) of a location in reference to a historic mean sea level taken as a vertical datum. In geodesy, it is formalized as ''orthometric heights''. The comb ...

, on coastal cliffs, coastal scrub nearby grassy slopes''.''

Conservation status

''Myosotis pansa'' subsp. ''praeceps'' is listed as Threatened – Nationally Vulnerable in the most recent assessment (2017–2018) of the New Zealand Threatened Classification for plants.

References

External links

''Myosotis pansa subsp. praeceps'' occurrence data from Australasian Virtual Herbarium
{{Taxonbar, from1=Q21383889, from2=Q17416949 pansa subsp. praeceps Endemic flora of New Zealand Flora of the North Island Endangered flora of New Zealand Plants described in 2013