Myosotis mooreana C.A.Lehnebach, 2012

Lehnebach, Carlos A., 2012, Two new species of forget-me-nots (Myosotis, Boraginaceae) from New Zealand, PhytoKeys 16, pp. 53-64 : 58-61

Myosotis mooreana C.A.Lehnebach sp. nov. Figs 3 -4

Diagnosis.

Similar to Myosotis forsteri and Myosotis brockiei , but differs from Myosotis forsteri by its obovate rosette leaves; larger leaves at base of the cyme and smaller calyx at fruiting. It differs from Myosotis brockiei by its smaller flowers (3.8 - 4.8 mm vs 9 - 10 mm); stamens included within the corolla tube; fruiting calyx with shorter pedicel (2.5 - 2.9 mm vs 3.6 - 4.3 mm); and hispid indumentum on leaves and petiole.

Type.

NEW ZEALAND.South Island, north-west Nelson: Kahurangi National Park, Cobb Reservoir, among leaf litter accumulated by the side of large boulders in forest, alt. ca 867 m, 6 January 2011, C.A.Lehnebach & A.Zeller s.n. (Holotype: WELT [WELT SP092756/A]; Fig. 3 ).

Plant perennial, ca 20 cm tall. Rosette leaves 5 - 12, obovate, 32.4 - 56 × 15.8 - 20.5 mm; apex mucronulate, ca 0.4 mm long. Leaf lamina base attenuate to petiole. Leaf indumentum hispid, hairs on upper surface sparsely distributed, antrorse, arcuate or erect. Hairs on the lower surface sparsely distributed, retrorse, arcuate or erect. Hairs arcuate or straight on margin. Petiole 26 - 40 × 1.4 - 1.8 mm, hispid, hairs erect, arcuate, antrorse or retrorse on margins. Flowering stem ascending, dark green to brown, 210 × 1.5 - 1.9 mm. Hairs, appressed, arcuate or erect, 0.8 - 2.1 mm long. Stem leaves elliptic-obovate, mucronulate, 15.3 - 35.4 × 6.4 - 14 mm, either shortly petiolate or sessile towards distal end of the inflorescence. Indumentum as for rosette leaves. Cyme with 15 - 31 flowers. Pedicel at fruiting, 2.5 - 2.9 mm. Calyx lobes lanceolate, 2.3 - 2.8 mm long, hairs inside calyx in upper half or along entire lobe. Fruiting calyx 2.7 - 2.8 mm long, hairs densely distributed, overlapping and hooked or straight. Corolla white with yellow scales, 3.8 - 4.8 mm across, lobes ovate, 2 × 1.6 - 1.8 mm; not overlapping, apex rounded or irregularly notched. Corolla tube 3 mm long. Stamens included within the corolla tube, with only the anther’s appendage above the scales. Filament attached below the scales. Anther 0.8 × 0.2 mm. Style 3 mm long, stigma clavate. Nutlet smooth, dark brown, ovoid to ellipsoid, 1.4 - 1.5 × 0.7 - 0.9 mm, ventral surface keeled.

Etymology.

This species is named in honour of Lucy Beatrice Moore, New Zealand botanist (http://www.teara.govt.nz/en/biographies/5m55/1) who described several species of endemic Myosotis and revised this genus for the Flora of New Zealand ( Allan 1961).

Distribution.

Endemic to New Zealand. Known from a single location in Kahurangi National Park, north-west Nelson (South Island). Detailed geographic coordinates are not shown to protect this species from illegal collection but are available from the author on request. It is likely Myosotis mooreana also occurs at two other sites within the Park (Shannel Courtney, personal communication) but this cannot be confirmed at this stage.

Conservation status.

Considering the small population size for this species (six individuals only), low number of mature individuals observed in the population and the small area of occupancy (less than 1m2), and following the New Zealand Threat Classification System ( Townsend et al. 2008), Myosotis mooreana should be rated as "Nationally Critical".

Ecology.

This is a perennial, fertile, self-pollinating species. It grows among the twigs and leaf-litter accumulated among large boulders under red beech ( Nothofagus fusca ) forest.

Discussion.

There are only two species of forget-me-nots in New Zealand that can be mistaken with Myosotis mooreana ; i.e. Myosotis brockiei and Myosotis forsteri . These two are the only species growing in a similar habitat, under forest or scrub in north-west Nelson and throughout New Zealand, respectively. The main differences between Myosotis mooreana and Myosotis brockiei are the large flowers with stamens fully exserted beyond the corolla tube in the latter species. Flowers in Myosotis mooreana are only ca 5 mm across and stamens are always included within the corolla tube. In contrast, Myosotis brockiei bears flowers ca 1 cm across and anthers with long filaments (ca 4 mm). When not fertile, indumentum and leaf shape are useful characters to distinguish between these two species. Myosotis mooreana bears oblanceolate rosette leaves and wide cauline leaves covered by a combination of arcuate, erect, antrorse and retrose hairs. Myosotis brockiei , in contrast, has narrowly elliptic leaves with a distinct tomentose almost greyish indumentum. Leaf shape is the most useful character to differentiate Myosotis mooreana from Myosotis forsteri . The latter species possess orbicular to broadly elliptic leaves with a well-defined petiole. The flowers of both species are very similar in size (see Table 1 ) but the calyx of Myosotis forsteri at fruiting is almost twice the size of the fruiting calyx of Myosotis mooreana .

Key to Myosotis chaffeyorum , Myosotis mooreana and other white flowered and laxly tufted species of Myosotis found in forest areas of New Zealand

1	Rosette leaf lamina obovate to narrowly elliptic	2
-	Rosette leaf lamina orbicular to broadly elliptic	3
2	Leaf and petiole indumentum tomentose; stem erect; calyx 3.9 - 4.4 mm at fruiting; stamens fully exserted from corolla tube	Myosotis brockiei
-	Leaf and petiole indumentum hispid; stem ascending; calyx ca 2.8 mm at fruiting; stamens included in corolla tube	Myosotis mooreana
3	Petiole of rosette leaves 1.9 - 3 mm wide; stem ascending; cyme well-defined; calyx ca 5 mm long at fruiting	Myosotis forsteri
-	Petiole of rosette leaves 0.2 - 0.6 mm wide; stem prostrate; cyme ill-defined; calyx <4.5 mm at fruiting	4
4	Indumentum on leaf margin, petiole and stem hispid; stem creeping, rooting at nodes	Myosotis spathulata
-	Indumentum on leaf margin, petiole and stem strigose; stem decumbent, no roots at the nodes	5
5	Indumentum on leaf surface hispid; pedicel 4.6 - 8.4 mm long at fruiting; calyx hairs arcuate; stamens fully exserted from corolla tube	Myosotis matthewsii
-	Indumentum on leaf surface strigose; pedicel 1.5 - 3 mm long at fruiting; calyx hairs straight; stamens included in corolla tube	Myosotis chaffeyorum

Figures

Figure 3. Photograph of the holotype of Myosotis mooreana C. A. Lehnebach. (C. A. Lehnebach & A. Zeller s. n., WELT SP 092756 / A).

Figure 4. Plant of Myosotis mooreana in situ (A) and close-up view of vegetative and reproductive structures (B Inflorescence C Rosette leaves D Stem leaves E Fertilised flower at leaf axil F Flower G Rosette leaf indumentum, upper surface H Rosette leaf petiole I Stem J Nutlets). Bar = 1 cm in A, C & D, 5 mm in B, 1 mm in E, F, H, I, J. Material from WELT SP 092756 / A.