Cynorkis adeleana Pailler, 2023

Pailler, Thierry, Robert, Charles-Henri, Flores, Olivier, Bytebier, Benny & Baider, Cláudia, 2023, Cynorkis adeleana, a new species of Orchidaceae (Orchidoideae; Habenariinae) endemic to Réunion, Phytotaxa 629 (2), pp. 181-186 : 181-184

Cynorkis adeleana Pailler , sp. nov. ( Fig. 1 )

Type:— RÉUNION: Massif du Piton de la Fournaise , 13 Apr 2012, fl., Pailler & Robert TPC43 (holotype: REU024618 ; isotype: REU024617 ).

Cynorkis adeleana closely resembles C. purpurascens in the shape of its flower but differs from the latter by having a lip near 60% larger (26.6 ± 0.2 vs 15.8 ± 1.1 mm) and nearly 70% shorter (14.6 ± 1.4 vs 21.3 ± 0.9 mm) with a slightly swollen spur. It differs from C. fastigiata in having around double the dimensions of the following characters: bracts (length: 19.7 ± 3.2 vs 9.2 ± 1.3 mm; width: 8.2 ± 1.3 vs 3.6 ± 0.7 mm), sepals (length: 10.5 ± 0.5 vs 5.1 ± 0.2 mm; width: 6.8 ± 0.2 vs 3.0 ± 0.2 mm), lip length (26.6 ± 0.2 vs 10.5 ± 0.5 mm) and petal length (9.7 ± 0.4 vs 4.9 ± 0.2 mm), a 30% longer peduncle (12.0 ± 1.2 vs 3.4 ± 0.7 mm) and a 25% shorter spur (14.6 ± 1.4 vs 19.4 ± 1.0 mm). Cynorkis adeleana has white flowers, whereas C. purpurascens has pink to mauve (rarely white) flowers, and C. fastigiata has pink or white flowers with purple markings. The column of C. adeleana has the stigmas under the rostellum arms, whereas in C. purpurescens and C. fastigiata , the stigmas are situated laterally on the rostellum arms and slightly project forward. The flowering period of C. adeleana (April to May) does not overlap with C. purpurescens (December to March) or C. fastigiata (November to March).

Terrestrial herbs, 21–35 cm tall. Basal leaf one, spreading, 15.0–22.0 × 7.0–11.0 cm, 9–11-veined base slightly conduplicate, clasping the stem, elliptic to ovate, apex subacute to acute. Peduncle thin, green, glabrous, with a single sheathing leaf in upper part; bract 2.8–3.2 cm, oval, acute to acuminate. Inflorescence 14.5–21.0 cm tall, subcapitate, secund, 2–13-flowered; rachis 3.0–4.0 cm; floral bracts 17.0–23.0 × 7.5–10.0 mm, shorter than the ovary, elliptic, attenuate to acuminate; ovary and pedicel 20.0–24.0 mm long, hairy, ovary 2.3–2.8 mm wide. Sepals greenish to greenish white, petals white tinted greenish at the base and lip white. Dorsal sepal 8.9–9.5 × 5.3–5.5 mm, triveined, broadly ovate, apex obtuse, lateral sepals 9.8–10.9 × 6.5–7.1 mm, triveined, obliquely ovate, obtuse, slighltly falcate. Petals 9.3–10.1 × 3.0– 3.5 mm, 1- veined, linear-falcate, obtuse, erect, forming a hood with the dorsal sepal above the column; lip 22.1–23.9 × 26.4–26.8 mm, 4-lobed; side lobes oblong to spatulate, apex truncate, margin irregular in places, side lobes 12.0 × 7.0 mm; midlobe 7.0 × 4.5 mm, slightly retuse, the midlobes resembling the side lobes but slightly smaller; spur 12.8–16.1 mm long, held horizontally, slightly curved, apex slightly swollen. Column 6.9–7.3 mm long; rostellum trilobed, midlobe projecting forward, 4.7–5.7 mm long; stigmatic arms 3.0– 3.7 mm long, slightly exerted, parallel to rostellum arms. Anther loculi 1.9–2.1 mm high, vertical, connivant towards the tip; caudicle 4.7–4.9 mm long; viscidium discoidal. Capsule unknown.

Etymology:— Dedicated to Adèle Robert, an orchid enthusiast, daughter of Charles Henry Robert, who discovered this new species.

Distribution and habitat:— Endemic to Réunion, in the understorey of mid-elevation tropical rain forest.

Phenology:— Flowering April-May.

Conservation status:— Consisting of six individuals in a few square meters so that the area of occupancy would be 4 km 2 (following the minimum 2× 2 km grid suggested by IUCN 2001). The extent of occurrence cannot be calculated because it is known from a single site. The species is threatened by invasive alien species, especially Ageratina riparia (Regel) King & Robinson (1970: 216 ; Asteraceae ) and Hedychium gardnerianum Sheppard ex Ker Gawler (1824 : t. 772; Zingiberaceae ). Although there is a risk of illegal collection, its rarity seems to protect it from this threat. The population has remained stable since it was first recorded in 2012 (C.H. Robert, pers. obs.). Its suggested conservation status ( IUCN, 2001) is critically endangered CR B1a b(iii)+B2a,b(iii).

Taxonomic and morphological notes:— On the basis of its morphology, as well as its phylogenetic position (results not shown), C. adeleana should be included in C. sect. Gibbosorchis Hermans ( Hermans et al., 2007: 290).

Albinistic forms of C. purpurascens are known (see Bernet 2010 p. 159, Szelengovicz & Tamon 2013 p. 282, Pailler & Henze 2020). They have the same morphology as the pink or purple-flowered ones but can be differentiated from C. adeleana ( Table 1 ). Moreover, the albinistic form of C. purpurascens with white sepals and petals differs from C. adeleana in which the sepals and petals have a green tinge ( Fig. 2 ).

Figures

FIGURE 1. Lankester composite dissection plate of the holotype (REU024618) of Cynorkis adeleana. A. Habit. B. Flower. C. Bract. D. Ovary. E. Dorsal sepal. F. Lateral sepal. G. Petal. H. Lip and column. I. Spur.

FIGURE 2. A. Detail of an albinistic flower of Cynorkis purpurascens. B. Detail of a flower of Cynorkis adeleana, showing the greenish tinge in the sepals and petals. C. Habit of an individual of Cynorkis adeleana. Photos by Frédéric Henze (A) and Charles-Henri Robert (B–C).