Corybas vitreus Lehnebach, 2016

Lehnebach, Carlos A., Zeller, Andreas J., Frericks, Jonathan & Ritchie, Peter, 2016, Five new species of Corybas (Diurideae, Orchidaceae) endemic to New Zealand and phylogeny of the Nematoceras clade, Phytotaxa 270 (1), pp. 1-24 : 12-13

4. Corybas vitreus Lehnebach , sp. nov. ( Fig. 9A–C)

Type:— NEW ZEALAND. South Island: north-west Nelson, Kahurangi National Park, track to Gordon’s Pyramid from Salisbury Lodge, 16 November 2011, Lehnebach, Frericks & Moorhouse SP104127 (holotype: WELT!).

Diagnosis:— C. vitreus resembles C. wallii in the overall pale colour of its flower but differs by its translucent labellum lamina with a non-isometric, dark maroon to purple band along the lateral margin and straight translucent lower margin. It can be distinguished from C. trilobus by its broadly ovate flower in frontal view and emarginate to retuse dorsal sepal.

Terrestrial herbs, 14–30 mm tall at flowering. Leaf distinctly petiolate, petiole (3.3)6.8–13(24.7) mm long; lamina cordiform, (3.3)8.5–11.3(14.1) × (7.8)12.3–16.0(19.6) mm; margin entire; apex mucronate with mucro (0.2)1.4–2(2.8) mm long. Flower solitary, held erect on a peduncle (0.7)2.7–5.5(8.1) mm long; floral bract triangular to widely deltoid when flattened, (1.8)3–4(6.8) × (1.3)1.8–2.4(3.2) mm; dorsal sepal pale green and less often with a few maroon streaks, concave to cucullate, arching over the labellum, narrow at the base and widely spathulate towards the tip, apex retuse to emarginated; lateral sepals linear-filiform, whitish to pale maroon, (12)15.4–21.6(26.7) mm long; petals are similar to the lateral sepals but longer, (21.3)33–43.6(56.5) mm long; labellum lamina mostly translucent, less often with a few streaks of maroon, covered with short trichomes, auriculate at base, aperture (1.2)1.8–2(2.6) mm in diameter; lamina deflexed, ca. 7 mm wide, with a central groove formed by the inwards folding of the lamina, extending downwards half way the labellum and sunken pit formed at the point where the lamina bends; lateral margin of the labellum incurving, entire, with a non-isometric dark maroon to purple band, lower margin translucent, straight and erose. Ovary (4.5)5.3– 7.1(8.4) mm long. Column 1.8 mm long, straight, round wings flanking the stigma. Senescent flowers with apex of the dorsal sepal pressing against the labellum blocking access to the column.

Specimens examined:— NORTH ISLAND: Boundary Stream Mainland Island , Kamahi loop track, 25 September 2012, Lusk SP104186 ( WELT) ; Eastern Ruahine Ranges , slopes opposite to Waipawa river , 26 September 2011, Lehnebach, Zeller & Lusk s/n, spirit collection ( WELT). SOUTH ISLAND: Kahurangi National Park, Salisbury track, 15 November 2011, Lehnebach, Frericks & Moorhouse SP104390 ( WELT) ; Kahurangi National Park , Gordons Pyramid route close to Salisbury track, 16 November 2011, Lehnebach, Frericks & Moorhouse SP104391 ( WELT) ; Kahurangi National Park , Gordons Pyramid route close to Salisbury track, 16 November 2011, Lehnebach, Frericks & Moorhouse SP104392 ( WELT) ; Kahurangi National Park , Gordons Pyramid route, 16 November 2011, Lehnebach, Frericks & Moorhouse SP104396 ( WELT) ; St Arnaud Range , road to Rainbow skifield, 10 November 2012, Lehnebach, Moorhouse & Upson SP104155 ( WELT) ; Arthur‘s Pass National Park , Avalanche Peak track, 10 December 2011, Lehnebach & Zeller SP104140 ( WELT) ; Mount Cook National Park , Governor‘s Bush track, 20 November 2012, Lehnebach & Zeller SP104158 ( WELT) ; Kinloch , Glacier Burn track, 23 November 2012 ; Lehnebach & Zeller SP104394 ( WELT) ; Routeburn track, track to Key Summit from the Divide, 25 November 2012, Lehnebach & Zeller SP104395 ( WELT) .

Etymology:— The epithet reflecting the transparent nature of the labellum of this species.

Distribution:— Endemic to New Zealand. North and South Islands ( Fig. 9D).

Habitat:— In leaf litter, under southern beech forest ( Fuscospora or Lophozonia , Nothofagaceae ) or Myrtaceae scrub, between 600 to 1300 m.

Phenology:—Flowering September to October; fruiting November to early January.

Conservation status:— Corybas vitreus is common in montane areas of the southern North Island and widespread in the South Island. It is, therefore, regarded as ‘Not Threatened’ using the criteria of Townsend et al. (2008).