Gastrodia cooperae Lehnebach & J.R.Rolfe, 2016

Lehnebach, Carlos A., Rolfe, Jeremy R., Gibbins, Jasmine & Ricthie, Peter, 2016, Two new species of Gastrodia (Gastrodieae, Orchidaceae) endemic to New Zealand, Phytotaxa 277 (3), pp. 237-254 : 242

Gastrodia cooperae Lehnebach & J.R.Rolfe , sp. nov. ( Fig. 4 )

Holotype:— NEW ZEALAND. North Island , Mangapakeha , Marangai Station , upper slopes of Kunzea robusta de Lange (2014: 155) forest, J. R. Rolfe , P. Enright & B. Campbell, 02 January 2013, WELT SP 100292 (Isotype: WELT SP 100293 ).

Diagnosis:— Similar to G. cunninghamii and Gastrodia molloyi in the colour and texture of the perianth but it differs from G. cunninghamii by its long column and from Gastrodia molloyi by its dark brown—black labellum tip. It differs from G. sesamoides by its dark brown—green verrucose perianth and dark brown—black labellum tip.

Description:— Terrestrial, leafless, achlorophyllous, deciduous herb. Rhizome tuberous, fusiform, pale brown. Plant (22)36–45.5(96) cm tall at flowering. Stem solitary, glabrous, dark to pale brown with greyish longitudinal streaks; (1.2)1.6–2.6(4.5) mm diameter. Stem bracts 4–5, papery, glabrous, sheathing. Inflorescence erect, terminal, flowers (6)12–27(40), non-resupinated, nectarless, scented, erect when developing and pendulous at anthesis. Floral bract papery, glabrous, deltoid to widely deltoid, apex acute, (2.1)4.7–5.4(6.6) × 1.6–2.2 mm. Pedicel (1.6)3.4–4.6(5.3) mm long. Perianth tube (4.9)8.4–10.4 × (2.5)3.6–4.6(5.3) mm, brown to dark brown, surface with pale green to gray wart-like elevations. Sepals reflexed, white to pale green abaxially; margin entire to slightly irregular towards the apex; apex acuminate. Petals adnate to the tube formed by the sepals, oblong, 3.0–3.4 × 1.3–1.8 mm, white on both sides; margin irregular, apex obtuse to round. Labellum 6.5–10.8 mm long; adnate to the base of the perianth, fleshy. Hypochile pale brown, covered on pseudo-pollen, margin entire. Mesochile strongly contracted; margins entire. Epychile trilobed, white at the base to pale yellow towards the apex. Lateral margins incurved, entire in the basal portion then irregularly crenate to cristate towards the apex. Labellum apex fleshy, dark brown to black. Two pale yellow ridges covered in pseudopollen extend from the mid-section of the epychile to the apex where they join. Column erect, 5.4–7.8 mm tall, narrow at base and wide towards the apex, 1.2–2 mm wide. One oblong or two deltoid wings flank the rostellum. Pollinia two, pollen joined into massulae; rostellum flap like, positioned under anther. Stigma at base of the column, ovate. Ovary (3.7)4.6–6.1(6.7) mm long, brown with a few greyish wart-like elevations. Capsules upright when mature; seeds pale brown.

Specimens studied:— NORTH ISLAND: Wairarapa, Marangai Station , Rolfe GASlcb1320 & Gibbins, 13 Dec 2013, WELT SP 104428 . SOUTH ISLAND: Takaka, Scott s.n., Dec 1952, CHR 79950 A, B ; Canaan Road , Druce s.n., Jan 1969, CHR 192308 ; Mount Arthur , Heine s.n., 12 Jan 1933, WELT SP 19098 ; Clarke Valley , Rolfe 15001, 6 Jan 2015, WELT SP 104437 .

Etymology:— The epithet of the species is adopted to recognise Dorothy ‘Dot’ A. Cooper (1941–) who established the New Zealand Native Orchid Group and who authored the Field Guide to New Zealand orchids ( Cooper 1981), which led to the recognition of this species as distinct.

Distribution:— Endemic to New Zealand. North Island, a single population in eastern Wairarapa. South Island, two populations in north-west Nelson ( Fig. 5 ).

Habitat:— G. cooperae is today known only from a remnant patch of Kunzea robusta forest in the North Island, and southern beech forest in the South Island. Information on the habitat of G. cooperae at its historical locations is lacking, but it is presumed to have habitat requirements similar to the closely related G. cunninghamii . The two species are syntopic in the South Island and G. cunninghamii is present at North Island sites where G. cooperae historically occurred.

Phenology:—Flowering in December and January; fruiting in January and February.

Conservation status:— The earliest specimens of Gastrodia cooperae were collected between the 1930s and 1960s from Mount Arthur (WELT SP19098 as G. cunninghamii ), Takaka (CHR 79950A, B) and Canaan Road (CHR 192308) (both as G. sesamoides ) in the South Island. A small population of ca. 10 plants had also been reported near Whanganui in the North Island during the 1980s and 1990s but it has not been seen there since that time (M. Pratt pers. comm.). It also seems to be no longer extant at the site of Cooper’s (1981, 1983) record in the southern Tararua Range in the North Island. Gastrodia cooperae is today known from only three locations. In eastern Wairarapa in the North Island, it is sparsely distributed across an area of ca. 0.2 ha within a ca. 10-ha forest. No formal census has been conducted there but it is unlikely that the population is greater than 100 individuals. In north-west Nelson, its area of occupancy is even smaller, and fewer than 20 plants have been observed there. Although no information is available to estimate population trends, the current situation of fewer than 250 mature individuals, enables G. cooperae to be assessed as Threatened: Nationally Critical A1 using the criteria of Townsend et al. (2008). Because of the lack of trend data and the large extent of unsurveyed potential habitat in the north-west South Island, we recommend that the qualifier DP (Data Poor) be appended to the assessment.

Figures

FIGURE 4. Gastrodia cooperae Lehnebach & J.R.Rolfe in the wild. A: Habit; B: Flower showing (i) tuberculate perianth surface, (ii) dark labellum apex, (iii) column apex; C: Longitudinal section of flower showing (i) dark labellum apex, (ii) column. Bar = 5 mm. Photos by J.R. Rolfe.

FIGURE 5. Extant and historical distribution of Gastrodia cooperae Lehnebach & J.R.Rolfe in New Zealand based on voucher specimens and verified photographic records.