Myosotis chaffeyorum 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 : 56-58

Myosotis chaffeyorum C.A.Lehnebach sp. nov. Figs 1 -2

Diagnosis.

Similar to Myosotis spathulata and Myosotis matthewsii , but differs from Myosotis spathulata by its well-defined, slender petiole; appressed, straight hairs on stem, petiole, leaf lamina and margin; and its decumbent stem not rooting at nodes. It differs from Myosotis matthewsii by its strigose indumentum on leaf upper surface; smaller flowers (3.7 - 4 mm across vs 5 - 8 mm across); stamens included in the corolla tube and fruiting calyx on shorter pedicel (1.5 - 3 mm vs 4.6 - 8.4 mm).

Type.

New Zealand. South Island, north-west Nelson: Takaka Valley, under overhanging limestone rock in forest, alt. ca 730 m, February 1977, A.P.Druce s.n. (Holotype: CHR [CHR 311719]; Fig. 1 ).

Plant perennial, 1.4 - 4.6 cm tall. Rosette leaves 6 - 9, lamina orbicular, 8.1 - 8.9 × 7.7 - 9.2 mm, apex mucronate, mucro ca 1 mm long. Leaf indumentum strigose, hairs on upper and lower surface sparsely distributed, non overlapping, appressed and antrorse. Hairs on leaf margin appressed. Petiole well-defined, 11.9 - 13.5 × 0.2 - 0.3 mm; hairs appressed, antrorse, sparsely distributed. Stem light brown, decumbent, not rooting at nodes, 59 - 100 × 0.3 - 0.5 mm. Stem hairs appressed as for leaves, hairs 0.2 - 0.6 mm long. Stem leaves elliptic or orbicular, 7.2 - 8.8 × 4.4 - 6.2 mm, mucronulate, shortly petiolate or sessile towards distal end of stem. Indumentum as for rosette leaves. Calyx lobes lanceolate, 1.5 - 2 mm long, hairs in upper half of the lobe only. Fruiting calyx 2.3 - 3 mm long; hairs appressed, straight, overlapping, not uniform in size. Flowers borne along the trailing stem, each usually opposite to a leaf. Pedicel at fruiting 1.5 - 3 mm long. Corolla white with yellow scales, 3.7 - 4 mm across. Corolla lobes obovate, not overlapping, 1.4 - 1.8 × 1.2 - 1.6 mm, apex rounded or irregularly notched. Corolla tube 2 - 2.2 mm long. Stamens included in the corolla, with only the anther’s appendage slightly above the scales. Filament attached below scales. Anther 0.5 × 0.2 mm. Style 1.8 mm long, stigma clavate. Nutlet smooth, light brown, ovoid to ellipsoid, 1.2 × 0.7 - 0.8 mm, ventral surface rounded.

Specimens examined.

New Zealand, South Island: north-west Nelson. Kahurangi National Park, upper Takaka River track, under overhang of limestone outcrop, alt. 857 m, 8 January 2011, C.A.Lehnebach & A.Zeller s.n. (WELT SP092173). Track along Takaka River, under overhang of limestone, alt. 736 m, 8 January 2011, C.A.Lehnebach & A.Zeller s.n. (WELT SP092172). Takaka Valley, alt. 900 m, under overhanging limestone rock in forest, February 1977, A.P. Druce s.n. (CHR 311720). Takaka River, near Ghost Creek Saddle, alt. 840 m, under overhang of limestone outcrop on dry loose fine soil, 22 April 2005, S. Courtney s.n. (NM 2688). Takaka Valley, Paynes Ford, at a base of limestone bluff, 30 October 2010, S. Courtney s.n. (NM 4835). Aniseed Valley. Valley down which Roding River, tributary of the Wairoa River, runs, 26 November 1967, R.H.S. (CHR 269160).

Etymology.

This species is named after Annie and Henry Chaffey (http://www.teara.govt.nz/en/biographies/4c15/1), who lived from ca 1913, for almost 40 years, as self-sustained, pioneers/exiles in this mountainous area of Kahurangi National Park. The tiny cottage they lived in still remains in place and served me as shelter during the expedition in which this new species was collected.

Distribution.

Endemic to New Zealand, only found in 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.

Conservation status.

Currently the existence of only five populations of this species can be confirmed. Two of them are within Kahurangi National Park where they occupy an approximate area of 6 m2 and 1 m2. The number of individuals at each site is low, ca 20 and 3, respectively. Three other populations are found outside the park, two of them in smaller protected areas which are regularly monitored by the Department of Conservation. At all these sites the species occupies a similar habitat and a small area (Shannel Courtney, personal communication). Considering this information and following the New Zealand Threat Classification System ( Townsend et al. 2008), Myosotis chaffeyorum should be considered as "Nationally Critical".

Ecology.

This is a perennial, self-pollinating species. It is habitat-specific and restricted to dry loose fine soil under shelters formed by limestone overhangs.

Discussion.

The earliest known collection of Myosotis chaffeyorum dates from 1967 (CHR 269160). Its distinctiveness from other species of Myosotis , however, was only noticed ca 10 years later when Anthony (Tony) Druce collected it while surveying the flora associated with Palaeogene calcareous rocks in north-west Nelson (Druce, unpublished). Druce noticed the overall similarity of this species to Myosotis matthewsii and Myosotis spathulata but also differences between them, which he wrote on the labels of the herbarium sheets of these collections (see Fig. 1 ). These notes read "cf. Myosotis matthewsii , but the flowers are smaller" and "cf. Myosotis spathulata , but stem not creeping".

Myosotis matthewsii and Myosotis spathulata are the only forget-me-nots in New Zealand with orbicular rosette leaves with which Myosotis chaffeyorum could be confused. The small flower with stamens within the corolla tube, the absence of roots at the nodes of the decumbent flowering stem and the strigose indumentum of the leaf lamina, petiole and stems of Myosotis chaffeyorum are key diagnostic characters to distinguish it from Myosotis matthewsii or Myosotis spathulata . In the absence of flowers, Myosotis matthewsii can be distinguished from Myosotis chaffeyorum by the presence of arcuate and erect hairs on the upper surface of the rosette leaves, larger leaves and a longer pedicel at fruiting (see Table 1 ). As for Myosotis spathulata , if no stems are present, it can be readily distinguished from Myosotis chaffeyorum by the hispid indumentum on the leaf petiole and larger leaf lamina (see Table 1 ).

Figures

Figure 1. Photograph of the holotype of Myosotis chaffeyorum C. A. Lehnebach. (A. P. Druce s. n., CHR 311719). Copyright Allan Herbarium (CHR), Landcare Research. New Zealand.

Figure 2. Plant of Myosotis chaffeyorum (A) and close-up view of vegetative and reproductive structures (B Flowering stem C Flower D Rosette leaves E Rosette leaf indumentum F Petiole G Stem H Node with flower and stem leaf I Nutlets). Bar = 1 cm in A & D, 5 mm in B & E, 1 mm in C, F, G, H, I. Material from WELT SP 092173 (D, E, F, G, H) and WELT SP 094151 (A, B, C, I).