Portulaca okinawensis Walker & Tawada var. amamiensis Kokubugata, Koh Nakam. & Yokota, 2013

Kokubugata, Goro, Nakamura, Koh, Hirayama, Yumiko & Yokota, Masatsugu, 2013, Taxonomic reexamination of Portulaca okinawensis (Portulacaceae) in the Ryukyu Archipelago of Japan based on molecular and morphological data, Phytotaxa 117 (1), pp. 11-22 : 21

Portulaca okinawensis Walker & Tawada var. amamiensis Kokubugata, Koh Nakam. & Yokota , var. nov.

Type :— JAPAN. The Ryukyus , the Amami Islands , Amami Island , Yamato, 6 September 2012, Kokubugata 15198 (holotype TNS!) .

Diagnosis: —Differt a var. okinawensi staminibus 12–15, petalis citrinis, obovatis vel oblanceolatis, caulibus viridibus.

Description: —Herbs perennial, 3–5 cm tall. Stems not articulated, diffuse, branched basally, ca. 1 mm thick; basal stems woody, prostrate, upper stems herbaceous, upright, bright green. Root fleshy, much-branched. Leaves spirally arranged to alternate, subsessile, without axillary hairs; leaf blade 2–3 mm thick, oblong to obovate, 5–8 mm long, base obtuse, apex obtuse or rounded. Flowers solitary, about 10–15 mm in diameter. Sepals 2, ovate-deltate, about 2 mm long. Petals 5, obovate, emarginate, rotund to obtuse, lemon-colored, with margins overlapping. Stames 12–15. Ovary ovoid. Stigma usually trilobed or tetralobed; capsule glossy, 2–4 mm long, 2–3 mm wide.

Etymology:— The epithet refers to the Amami Islands, the locus classicus.

Distribution and habitat:—Endemic to the Amami Islands (the Ryukyus), in Amami and Tokuno-shima islands. Coastal rocky slopes, xeric, saline, and exposed to direct sunlight. In Kakeroma Island, being an islet situated in the Amami Island, P. okinawensis has been recorded. However, we could not obtain and investigate samples from the island.

IUCN Red list category: —It can be included in the Data Deficient (DD) category of IUCN Red List categories ( IUCN 2010) as there are inadequate information to make a direct or indirect assessment of its risk of extinction based on its distribution and/or population status.

Additional specimens examined (paratypes):— JAPAN. The Ryukyus, the Amami Islands: Amami Island, Amami ( AM1 ), 3 November 2010, Kokubugata 12939–12942, 7 September 2012, Kokubugata 15434–15443 ( TNS) ; Amami ( AM2 ), 18 October 2008, Kokubugata 11096–11100 ( TNS) ; Yamato ( AM3 ), 6 September 2012, Kokubugata 15197–15202 ; Uken ( AM4 ), 18 October 2008, Kokubugata 11081–11085, 11102 ( TNS) ; Tokuno-shima Island, Amagi ( TK) , 17 October 2007, Kokubugata 12140–12144 ( TNS) .