Lepidium makateanum Sykes, 2014

Sykes, W. R., 2014, A new species of Lepidium (Brassicaceae) in the Cook Islands, Phytotaxa 181 (3), pp. 184-187 : 186-187

Lepidium makateanum Sykes , sp. nov.

Fruticulus vel suffrutex parvus erectus usque 30 cm altus, plerumque habitu dense ramoso; et caules et rami inflorescentiae leniter puberulentes; folia usque 3 × 0.7 cm, anguste sublinearia vel oblanceolata vel anguste oblongo-lanceolate, plerumque integra; siliculae 4–5.5 mm longae, late ellipticae praetor sinum apicalem plus minusve ad ambas extremitates rotundatae; stylus persistenter exsertus.

Type:— COOK ISLANDS. Miti‘aro , Ka‘apoto, coastal makatea with much sand, 22 Aug 1982, W. R . Sykes 2413/ CI (holotype CHR 399610 !) .

Small erect shrublet or subshrub to c. 30 cm high, generally with a dense bushy habit; stems and inflorescence branches densely and finely puberulent; main stems with prominent semi-annular leaf scars. Leaves peppery to taste; basal rosette leaves ephemeral; cauline leaves concentrated in upper part of stems, sessile or shortly and indistinctly petiolate, glabrous; lamina to c. 3 × 0.7 cm, from almost narrow linear to oblanceolate or narrow oblong-oblanceolate, usually entire, occasionally with up to 4 small lateral teeth; base attenuate, apex from almost rounded to acute or mucronate. Inflorescence of erect simple racemes to 4 cm long; pedicles 2–4 mm long, elongating to c. 8 mm in fruit, puberulence of raceme rachis and pedicels as on stems. Sepals 1–1.5 mm long, ± broadly elliptic, almost glabrous except sometimes for a few hairs outside down the centre; margins white or translucent white. Petals 1.5–2.3 mm long, spathulate or oblanceolate to broad obovate, white; limb 0.6–1.2 mm wide. Stamens 6 (<petals, longer ones only slightly less); anthers c. 0.5 mm long. Silicles 4.5–5.5 mm long, rounded-elliptic, often as wide as long; apically notched with style shortly exserted. Seed 2–2.5 mm long, obovoid, somewhat flattened, tending asymmetric, medium brown, minutely papillate, with a narrow groove around position of the plumule; radicle incumbent. Flowering occurs throughout much of the year but the main period is probably in the cooler months from June to September.

Distribution and habitat:—Southern Cook Islands, Ngaputoru Group, Miti‘aro. Lepidium makateanum is only found in a few northern and eastern parts of the coastal makatea in open places and in low scrub. Locally common where it does occur.

Etymology:—The Latin name denotes the habitat, much of the island of Miti‘aro being composed of raised jagged coral rock or makatea that is such a feature of a number of islands in Polynesia, including its near neighbours in the Southern Cook Islands.

Additional specimens examined:— COOK ISLANDS. Miti‘aro , Ka‘apoto, 22 August 1982, W. R . Sykes 2411/ CI ( CHR 399609 ); Miti‘aro, south of Omutu Landing, 21 August 1982, W. R . Sykes 2401/ CI ( CHR 399613 ); Miti‘aro, Omapere, inland side of road, 24 July 1991, C . Luttrell 226 ( CHR 587431 ); Miti‘aro , 26 July 1984, Merlin 326 ( CHR 433883 ); Miti‘aro, N. E . Coast , July 2004, B . Maxwell s.n. ( CHR 592458 ) .

Notes: —The area of exposed makatea where the undescribed species grows is also where the small cushionforming composite Tetramolopium mitiaroense Lowrey, Whitkus and Sykes (2005: 448) is found. This plant also does not grow elsewhere in the Cook Islands and is again endemic to Miti‘aro. Very close relations of both of these Miti‘aro endemics grow in Hawai‘i where they are also endemic.