''Myosotis brockiei'' subsp. ''dysis'' is a

subspecies In biological classification, subspecies is a rank below species, used for populations that live in different areas and vary in size, shape, or other physical characteristics (morphology), but that can successfully interbreed. Not all species ...

of flowering plant in the family Boraginaceae, endemic to southern

South Island The South Island, also officially named , is the larger of the two major islands of New Zealand in surface area, the other being the smaller but more populous North Island. It is bordered to the north by Cook Strait, to the west by the Tasman ...

of New Zealand. Shannel Courtney and Heidi Meudt described this subspecies in 2021. Plants of this subspecies of forget-me-not are perennial rosettes which form

stoloniferous In biology, stolons (from Latin '' stolō'', genitive ''stolōnis'' – "branch"), also known as runners, are horizontal connections between organisms. They may be part of the organism, or of its skeleton; typically, animal stolons are external ...

mats, with long, ebracteate, erect inflorescences, and white corollas with exserted stamens.

Taxonomy and etymology

''Myosotis brockiei'' subsp. ''dysis'' Courtney & Meudt is in the plant family Boraginaceae. The species '' M. brockiei'' was described by Lucy Moore and Margaret Simpson in 1973, whereas the subspecies ''dysis'' was described in 2021. The holotype specimen of ''Myosotis brockiei'' subsp. ''dysis'' was collected from Lake Otuhie, Western Nelson, by Michael Thorsen and is housed at the

herbarium A herbarium (plural: herbaria) is a collection of preserved plant specimens and associated data used for scientific study. The specimens may be whole plants or plant parts; these will usually be in dried form mounted on a sheet of paper (called ...

of the

Museum of New Zealand Te Papa Tongarewa The Museum of New Zealand Te Papa Tongarewa is New Zealand's national museum and is located in Wellington. ''Te Papa Tongarewa'' translates literally to "container of treasures" or in full "container of treasured things and people that spring fr ...

(WELT SP089878). There are also isotypes at Manaaki Whenua - Landcare Research Allan Herbarium (CHR 596689/A and CHR 596689/B). The subspecies name ''dysis'' is one of the Greek Horae (hours) or daughters of Chronos (time), and is in reference to the west, where the sun sets, reflecting the western distribution of this subspecies relative to the other subspecies. This is one of two subspecies recognized in ''M. brockiei;'' the other is ''M. brockiei'' subsp. ''brockiei''''.'' The subspecies are

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. brockiei'' subsp. ''dysis'' is found in lower elevations near the coast on limestone or other calcicolous substrates, whereas ''M. brockiei'' subsp. ''brockiei'' is found at higher elevations in montane and subalpine in habitats with limestone or other calcicolous or ultramafic substrates. ''Myosotis brockiei'' subsp. ''dysis'' differs from ''M. brockiei'' subsp. ''brockiei'' by three minor characters, i.e. its habit (

mats instead of single rosettes or tufts instead), obtuse apices of the lower cauline leaves, and lack of retrorse (backward facing) hairs on the scape below the flowering portion of the inflorescence.

Phylogeny

''Myosotis brockiei'' subsp. ''dysis'' has not yet been included in any phylogenetic analyses.

Description

''Myosotis brockiei'' subsp. ''brockiei'' plants are single rosettes that often grow together to form

mats. The rosette leaves have petioles 16–41 mm long. The rosette leaf blades are usually 15–50mm long by 4–20 mm wide (length: width ratio 2.5–3.6: 1), oblanceolate or rarely narrowly obovate, widest at or above the middle, with an obtuse apex. The upper surface of the leaf is densely covered in mostly flexuous, some curved, patent to erect, antrorse (forward-facing) hairs that are oriented oblique to the mid vein. The hairs on the edges are similar but mostly erect, and the hairs on the underside of the leaf are also similar but mostly retrorse (backward-facing) and can be oriented parallel or oblique to the mid vein. Each rosette has 1–6 erect, usually once-branched (sometimes unbranched), ebracteate inflorescences that are up to 385 mm long and are bifurcating in an open, forked 'V' shape near the tips. The cauline leaves are similar to the rosette leaves but smaller with shorter petioles, and decrease in size toward the tip. Each inflorescence has up to 47 flowers, each borne on a pedicel up to 13 mm long at fruiting, and each without a bract. The scape below the flowering portion of the inflorescence has hairs that are antrorse to erect (with some retrorse only at the very base). The calyx is 2–7 mm long at flowering and 3–9 mm long at fruiting, lobed to half to three-quarters of its length, and densely covered in mostly antrorse (retrorse near the base), mostly patent and flexuous hairs. The corolla is white, up to 13 mm in diameter, with a cylindrical tube, petals that are narrowly ovate, obovate or broadly obovate, and small yellow scales alternating with the petals. The anthers are fully exserted above the scales. The four smooth, shiny, light to dark brown nutlets are 1.8–2.5 mm long by 1.0–1.3 mm wide and narrowly ovoid or ovoid in shape. The chromosome number of ''M. brockiei'' subsp. ''dysis'' is unknown. The pollen of ''M. brockiei'' subsp. ''dysis'' is unknown. It flowers and fruits from December–January.

Distribution and habitat

''Myosotis brockiei'' subsp. ''dysis'' is a forget-me-not subspecies endemic to Western Nelson, South Island, New Zealand from 0–260 m ASL. It is found on faces or ledges of limestone cliffs, on sites with a lowland climate near the coast, and is considered to be an obligate calcicole.

Conservation status

The species is listed as Threatened - Nationally Vulnerable on the most recent assessment (2017-2018; as ''Myosotis'' aff. ''brockiei'' (a) (CHR 497375; Lake Otuhie)) under the New Zealand Threatened Classification system for plants, with the qualifier "OL" (One Location).

References

External links

''Myosotis brockiei subsp. dysis'' occurrence data from Australasian Virtual Herbarium
* {{Taxonbar, from=Q111781551, from2=Q17416584 brockiei subsp. dysis Endemic flora of New Zealand Endangered flora of New Zealand Flora of the South Island Plants described in 2021