Spiranthes hongkongensis S.Y. Hu & Baretto (1976: 2)

Suetsugu, Kenji & Hsu, Tian-Chuan, 2023, Taxonomic revision of the genus Spiranthes (Orchidaceae) in Taiwan, Phytotaxa 578 (1), pp. 1-10 : 5

Spiranthes hongkongensis S.Y. Hu & Baretto (1976: 2) — Fig. 3 .

Type:— HONG KONG: Tai Po , the garden of Gloria Barretto, 4 April 1975, S. Y. Hu 13658 (holotype: K000942682!; isotypes:A00104456, image!, CUHK) .

Synonym:— Spiranthes suishaensis auct. non ( Hayata 1916: 86) Schlechter (1919: 161): Lin (2019: 284).

Morphological descriptions and illustrations: —See Hu & Baretto (1976: 2; f. 2), Hsu & Chung (2014: 406; f.1; 2016: 186), Surveswaran et al. (2017: 125; f. 4), and Lin (2019: 265; f. 116; pl. 13), as Spiranthes suishaensis .

Distribution and ecology: — Spiranthes hongkongensis is currently known in Hong Kong, Taiwan, China (Guangdong and Hainan Provinces), Japan, and Borneo. In Taiwan, this species is occasionally found on lowland hills around the Taipei Basin where it grows on very humid sunny grassland accompanied with some wetland plants such as Eriocaulon spp. and Utricularia spp. It was also found growing as a weed in some greenhouses in southern Taiwan, and these populations are presumed as unintentionally introduced along with horticultural plants. Flowers were observed from April to May.

Additional specimens examined: — TAIWAN. New Taipei City: Chepingliao , 27 May 2009, T.-C. Hsu 2214 (TAIF!); same loc., 20 April 2014, T.-C. Hsu 7079 (TAIF!); same loc., 8 May 2015, T.-C. Hsu 7674 (TAIF!); same loc., 22 April 2017, J.-Z. Lin 1 (TAIF!) . Pingtung Co.: Kaoshu , 26 April 2018, T.-C. Hsu 10536 (TAIF!) . CHINA. Hainan Prov.: Mt. Diaoluo National Forest Park , 26 February 2012, T.-C. Hsu 5440 (TAIF!) . HONG KONG: 20 April 1975, S. Y. Hu 13673 (KYO!) . JAPAN. Okinawa Pref.: Ishigaki Island , Ishigaki City, in campis humidis litoris ad Nagura , 4 April 1937, Takamine s.n. (KPM-NA0304131!) .

Taxonomic remarks: — Spiranthes hongkongensis can be distinguished from the allogamous taxa such as S. australis and S. sinensis by its modified rostellum and stigma morphology associated with its autogamous breeding system. Spiranthes hongkongensis is most similar to S. nivea , another autogamous species with white flowers. However, it differs from S. nivea , in having papillate (vs. nearly glabrous) labellum disc, larger papillate (vs. smaller glabrous) basal labellum callosities, and densely glandular pubescent (vs. sparsely pubescent) rachis, ovaries, and sepals.

Figures

FIGURE 3. Spiranthes hongkongensis (Tian-Chuan Hsu 7079, TAIF). (A) Habit. (B) Flower, front view. (C) Flower, lateral view. (D) Dorsal sepal. (E) Petal. (F) Lateral sepal. (G) Labellum. (H) Labellum and column, lateral view. (I) Flattened labellum. (J) Close-up of basal callosities of labellum. (K) Ovary and column. (L) Column. Scale bars: 30 mm (A), 3 mm (B–I), 0.5 mm (J) and 1 mm (K–L).