Corybas sanctigeorgianus 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

3. Corybas sanctigeorgianus Lehnebach , sp. nov. ( Fig. 8A–C )

Type :— NEW ZEALAND. North Island , Hunua Regional Park, Wairoa Loop track, 10 August 2012, Lehnebach & Zeller SP104149 (holotype: WELT!) .

Diagnosis:—Similar to C. hypogaeus in flower and leaf shape but it can be distinguished by its straight ovary, labellum with a white centre and dorsal sepal extending beyond the labellum. It differs from C. trilobus by its long dorsal sepal and the white centre of the labellum.

Terrestrial herbs, 14–20 mm tall at flowering. Leaf distinctly petiolate, petiole (9.0)–9.8–12.7–(22.6) mm long; lamina reniform to cordiform, (8.5)10.0–13.2(13.8) × (12.6)14.0–19.0(20.3) mm; margin entire; apex acuminate (1.5)2.1– 2.7(3.3) mm long. Flower solitary, held erect on a peduncle (2.5)3.3–3.9(4.4) mm long; floral bract ovate when flattened, (3.7)4.4–5.8(7.6) × (2.0)2.1–2.5(2.7) mm; dorsal sepal light green with a few blotches of dark red, arching over the labellum, concave to cucullate, narrow at the base and wide towards the tip, apex rounded or slightly mucronate; lateral sepals linear-filiform, white or translucent with dark red specks, (11.8)15.0–18.0(19.8) mm long; petals similar to the lateral sepals but longer, (32.8)38.9–47(53.3) mm long; labellum white in the centre, dark red towards the margins, and covered with short trichomes, auriculate at base; aperture (1.5)1.7–2.0(2.1) mm diameter; lamina deflexed, ca. 5 mm wide, with a central groove formed by the inward folding of the lamina, extending downwards half way the lamina and sunken pit formed at the point where the lamina bends, lateral margins incurve, mostly entire, lower margin laciniate to finally denticulate. Ovary (3.3)–4.0–4.4–(5.3) mm long. Column 1.8 mm long, straight, with truncate column wings on both sides of the stigma.

Specimens examined:— NORTH ISLAND: Auckland, Hunua Regional Park, September 2012, Gaskett SP104166 ( WELT); Auckland, Hunua Regional Park, September 2012, Scanlen SP104167 ( WELT) .

Etymology:— This species is named in honour of Ian Saint George, who has greatly contributed to the knowledge of NZ orchids and promoted their study and conservation.

Distribution:—Endemic to NZ, known only from the Hunua Ranges in the North Island ( Fig. 8D ).

Habitat:— In leaf litter under scrub or podocarp-broadleaved forest, gravelly soil or decaying trunks of tree ferns, 140– 330 m.

Phenology:—Flowering mid-August to September; fruiting October to early November.

Conservation status: —This species is only known from the type locality where a population of about hundred individuals occurs. Scanlen & St. George (2011) noted a second site existed in the 1960s, but this has now been lost. Based on these observations, our field observations and following the New Zealand Threat Classification System ( Townsend et al. 2008), C. sanctigeorgianus should be ranked as “Nationally Critical”.

Figures

FIGURE 8. Corybas sanctigeorgianus, a new species of spider orchid endemic to New Zealand. A. Plant in the wild. B. Close up of the labellum. C. Side view of the flower. D. Distribution. Scale bar = 5 mm. Photos by P. Shearer.