Gastrochilus pseudocalceolaris S. Dey, L. Phom, Av. Bhattacharjee, Moaakum & K. Eshuo, 2022

Dey, Santanu, Phom, Limamanen, Bhattacharjee, Avishek & Eshuo, Kazhuhrii, 2022, Gastrochilus pseudocalceolaris, a new species of epiphytic orchid from India, Phytotaxa 574 (4), pp. 295-300 : 295-299

Gastrochilus pseudocalceolaris S. Dey, L. Phom, Av. Bhattacharjee, Moaakum & K. Eshuo , sp. nov. FIGURE 1 , 2

Types:— INDIA. Nagaland, Longleng district, Yingyushang Mountain , 1854 m, 7 April 2022, S. Dey 1342 (holotype CAL!, barcode CAL0000217503 ; isotype CAL!, barcode CAL0000217504 )

Diagnosis: — Gastrochilus pseudocalceolaris is morphologically allied to G. calceolaris , but differs in having much shorter stem and a labellum-epichile without long, papillose hairs on its adaxial surface, and epichile with shortly erose margins.

Description: —Epiphytic, pendent herbs, 12–16 cm long (including leaves). Roots velamenous, up to 12 cm long, thin. Stem 1–3 cm long, 0.5–1 cm thick, internodes clasped with sheathing leaf bases. Leaves 4–5, narrowly oblong to linear-lanceolate, 6–15 × 0.6–2 cm, fleshy, nearly flat, with narrower bases, unequally bifid at apex, sheathing and articulate at base. Inflorescences lateral, 1–2.5 cm long, subumbellate, 4–6-flowered. Floral bracts ovate-triangular, ca. 0.2 × 0.15 cm, much shorter than pedicel plus ovary, pale pinkish-brown, acute to subacute at apex. Flowers 1.7–2.3 cm long, 1.2–1.5 cm across, faintly fragrant; sepals and petals yellowish-green blotched with reddish-brown; hypochile greenish-yellow, spotted with purplish-red; epichile white except the yellow, subtriangular disc near center, blotched with purplish-red; pedicel plus ovary 1.3–1.6 cm long. Sepals subequal, obovate-oblong to obovate-lanceolate, 0.5–0.7 × 0.18–0.24 cm, spreading, obtuse at apex, laterals slightly narrower. Petals obliquely oblong-obovate to oblongspathulate, 0.5–0.65 × 0.18–0.22 cm, spreading, obtuse at apex. Labellum adnate to lower half of column; hypochile cup-shaped, 0.6–0.7 × 0.5–0.6 cm, rim of hypochile forming almost oblique to subvertical front edges with the base of epichile; epichile subreniform to subovate, 0.2–0.25 × 0.4–0.4.8 cm, without any long, papillose hair on adaxial surface, with a few minute blister-like protuberances near central cushion, with a cavity at base of cushion, abaxial surface glabrous, shortly erose at margins. Column 0.2–0.3 cm long. Anther 0.16–0.2 × 0.18–0.2 cm; pollinia 2, ovoidelliptic, 0.07–0.09 × 0.04–0.07 cm, monoporate; stipe linear, 0.14–0.18 cm long, hyaline; viscidium oblong-elliptic, 0.05–0.08 × 0.04–0.06 cm. Capsule ca. 2 × 0.6 cm, with 4 ridges, dark brown in maturity.

Flowering & Fruiting: —Both observed in April.

Habitat: —On tree trunks and branches in subtropical semi evergreen forest at 1854 m elevation; abundance rare.

Distribution: — INDIA: Nagaland (Endemic)

Etymology: —The specific epithet is derived from the Greek ‘ pseudo-’ (false) and after ‘ Gastrochilus calceolaris ’ referring to its close similarity with G. calceolaris .

Note: —Though Gastrochilus pseudocalceolaris apparently looks alike to G. calceolaris , it can be distinguished by its much shorter stem (1–3 cm long), labellum-epichile without numerous, long, papillose hairs on its adaxial surface, and epichile with shortly erose margins ( FIGURE 1 , 2 , 3 D, E ). G. calceolaris is a highly variable species which is reported from Nepal to Hainan and West Malesia ( Liu et al. 2019, Govaerts et al. 2022). Bhattacharjee et al. (2021) reported variations (based on freshly collected as well as herbarium-specimens) in G. calceolaris with respect to stem length (4–10 cm long); size of the leaves and nature of apex; number and size of the flowers; size, density and intensity of blotches on perianth; texture and thickness of sepals, petals and labellum; the cupular hypochile with or without a rim at the juncture with the epichile; density and distribution of papillate hairs on epichile; shape and margins of epichile; and presence or absence of purplish spots on the yellow cushion on the epichile. Though in all studied specimens of G. calceolaris , numerous, long, papillose hairs on the epichile are prominent ( FIGURE 3 A, B ), these are completely lacking in G. pseudocalceolaris and is the most prominent diagnostic character of the new species. Based on morpho-molecular studies, Liu et al. (2019) separated two new species from G. calceolaris and described G. changjiangensis Q. Liu & M.Z. Huang and G. zhenyuanensis Q. Liu & D.P. Ye. , but they did not report any specimen of G. calceolaris without numerous, long, papillose hairs. Gastrochilus pseudocalceolaris is also close to G. acaulis ( Lindley 1833: 227) Kuntze (1891: 661) , but the shape of sepals and petals are different (broadly obovate to spathulate and much incurved) in G. acaulis and it has a projection inside the hypochile ( FIGURE 3C ) which is absent in the new species.

Figures

FIGURE 1. Gastrochilus pseudocalceolaris S. Dey, L. Phom, Av. Bhattacharjee, Moaakum & K. Eshuo. A–B. Photograph of plant in natural habitat; C. Habit.

FIGURE 2. Gastrochilus pseudocalceolaris S. Dey, L. Phom, Av. Bhattacharjee, Moaakum & K. Eshuo. A. Habit; B. Flower; C. Portion of inflorescence; D. Dorsal sepal; E. Petal; F. Lateral sepal; G. Labellum, column and pedicel plus ovary; H. Labellum with portion of column and pollinarium; I. Flower; J. Labellum, column and pedicel plus ovary; K. Labellum; L. Pollinarium; M. Dehisced capsule showing seeds. [From S. Dey 1342 (Holotype and isotype); I–M: From preserved flowers taken from S. Dey 1342 before mounting]

FIGURE 3. Labellum of – A, B. Gastrochilus calceolaris (Buch.-Ham. ex Sm.) D. Don; C. G. acaulis (Lindl.) Kuntze; D, E. G. pseudocalceolaris S. Dey, L. Phom, Av. Bhattacharjee, Moaakum & K. Eshuo.