Eucosia carnea Blume (1825: 415)

Suetsugu, Kenji & Hsu, Tian Chuan, 2021, Taxonomic notes on the genus Eucosia (Orchidaceae) in Japan and Taiwan, Phytotaxa 520 (2), pp. 215-224 : 215-216

Eucosia carnea Blume (1825: 415) . Figs. 1 (A–D), 2 & 3.

≡ Goodyera carnea (Blume) Schlechter in Schumann & Lauterbach (1905: 93), nom. illeg. Type:— INDONESIA. West Java: Mt. Salak (“in humidis montis Salak prope Passir Java ”), C. L. Blume s.n. (holotype: L0061220 image!)

= Eucosia hengchunensis Hsu in Hsu & Chung (2016: 34); Goodyera viridiflora var. hengchunensis (Hsu) Lin (2019: 163) , syn. nov. Type:— TAIWAN. Pingtung: Shouka, 300–400 m, 3 Jan 2016, T.C. Hsu 8166 (holotype: TAIF496951!)

Morphological descriptions and illustrations: —See Blume (1858: 48; pl. 12b, f. 3; pl. 42, A) and Smith (1909: f. 96); Hsu & Chung (2016: 34), as Eucosia hengchunensis ; Lin (2019: 163; f. 66-2), as Goodyera viridiflora var. hengchunensis .

Distribution: —This species is currently disjunctively recorded from Indonesia (Java), Taiwan (Pingtung) and S Japan (Okinawa and Kagoshima).

Additional specimens examined: — TAIWAN. Pingtung: Hsuhai, 1 January 2015, Hsu 7413 ( TAIF); 18 October 2016, Chung 12666 ( TAIF); 1 November 2016, Chung 12666 ( TAIF) . JAPAN. Kagoshima: Takarajima Island , 15 March 1979, H . Ueno 364 ( KAG) . Okinawa: Okinawa Island, Kunigami, Ada , 2 December 2020, Y . Miyazato KS807 ( KYO) , Okinawa Island, Kunigami, Hiji , 14 December 2020, Y . Miyazato KS808 ( KYO) , Okinawa Island, Kunigami, Iji , 14 December 2020, Y . Miyazato KS809 ( KYO) .

Taxonomic remarks: — Eucosia carnea could be characterized by the ovate, thin-textured, adaxially glossy pale green leaves without conspicuous reticulate venation, small, usually cleistogamous flowers with 7–9 mm long sepals and petals, and the columns that are lacking the long protruding rostellum typically found in other congeneric species. The morphological synapomorphies among populations found in wide areas including Japan, Java and Taiwan and distinctiveness against other Eucosia species implies that this entity is not just an “abnormal form” of E. viridiflora as suspected by Smith (1905), Schuiteman (1996) and Lin (2019) but an isolated lineage that is better kept as an independent species. Although Lin (2019) suspected that the deterioration of column structure lead to demographic collapse and extinction, E. carnea possesses a selfpollination system, allowing contact between the stigma and pollinaria and producing many viable seeds. Its widespread distribution indirectly supports the effectiveness of the reproductive strategy. We thus treat this taxon as an independent species rather than an infraspecific taxon of E. viridiflora . This notion is also based on biological species concept, which defines a species as a group that can interbreed in nature, because obligate selfing in E. carnea eliminates potential gene flow with other Eucosia species. Due to its historical confusion with Eucosia viridiflora , detailed studies are still needed to clarify its exact geographic range.

Figures

FIGURE 1. Morphological comparison of Eucosia species.A–D. E. carnea; A–C from Taiwan (Hsu 8166, TAIF); D from Japan (H. Ueno 364, KAG). E–H. E. cordata; E–G from Taiwan (Hsu 4615, TAIF); H from Vietnam (Hsu 12391, TAIF). I–L. E. longirostrata; I–K from Taiwan (Hsu 4262, TAIF); L from China (Hsu 6525, TAIF). M–P. E. viridiflora; M–O. from the Philippines (Hsu 6994, TAIF); P. from the Solomon Islands (Hsu et al. SITW01587, TNM). Scale bars = 1 cm.