Cyrtandra rubriflora P.E.Sm. & H.J.Atkins, 2020

Cyrtandra rubriflora P.E.Sm. & H.J.Atkins View in CoL , sp. nov. FigS. 1 View Fig & 2 View Fig

This species is similar to the widespread C. picta Blume in being a herb with subsessile inflorescences and large, slightly connate bracts that enclose the base of the inflorescence, and a glabrous ovary. It differs in corolla colour (dark pink to red vs white, cream or pale yellow with purple dots in the throat); leaf shape (elliptic vs ovate) and anther indumentums (glabrous vs with a short tuft of simple hairs at the tips and along the connective).

Type: INDONESIA, Sumatra, Aceh, Gunung Leuser National Park, Ketambe Research Station , 08.03.2008, P. Wilkie, M. Hughes, A. Sumadijaya, S. Rasnovi, Marlan & Rabusin PW630 (holo E [E00416358!]; iso BO [BO1880564!]) .

Erect herbs 30–100 cm tall. Stems terete to quadrangular, striate, glabrate. Leaves opposite and subequal, some pairs slightly anisophyllous. Petiole 4–10 cm long, sparsely hairy, more densely so when young, hairs simple and matted. Blade elliptic, 6.0– 9.5 × 14–21 cm, base cuneate, somewhat soblique, apex acuminate, 8–20 mm long, margins serrate, upper surface more or less glabrous, lower surface with a sparse covering of simple hairs ( c. 1 mm long), dense over midrib and veins, lateral leaf vein pairs 6–7. Inflorescence axillary, subsessile or shortly pedunculate, occurring from base of plant to about half way up the stem, usually below the leaves, four or more flowers per inflorescence; bracts c. 13 mm long, enclosing the base of the inflorescence, dark green to brown, with an indumentum of simple, matted hairs less than 1 mm long. Peduncles 2–3 mm long with dense, simple, matted hairs c. 1 mm long. Pedicels 2–3 mm long. Calyx yellow-green somewhat translucent, turning brown with maturity, tubular, 15–20 mm long, lobes four or five, narrowly acuminate, 2–3 mm long, externally with c. 1–3 mm long simple hairs, internally glabrous. Corolla dark pink to red, 43–50 mm long, tube narrow whilst within the calyx, widening to mouth, somewhat compressed laterally, lobes spreading, slightly recurved, posterior lobes c. 11 × 8 mm, lateral lobes c. 8 × 6 mm and anterior lobe 8 × 8 mm, externally with 4–7 mm long simple hairs, internally glabrous. Stamens 2, white, filaments 10– 12 mm long, glabrous; anthers creamy-yellow 2– 2.5 mm long, face to face and cohering at tips, thecae distally confluent, but proximally separate, glabrous; lateral staminodes 1.5 mm long, posterior staminode not seen. Gynoecium 22 mm long, disk cupular, 2 mm long, glabrous, with an undulate margin; ovary glabrous, style white with short, 0.5 mm hairs distally; stigma bilobed. Fruit ovoid, somewhat scabrous, c. 10 × 4 mm, base of style and calyx persistent, glabrous, immature.

Flowering & fruiting: From January to May (based on limited material available).

Habitat: Lowland forest, often riparian, 200–400 m elevation.

Distribution: Sumatra, Aceh province ( Fig. 3 View Fig ).

Etymology: The specific epithet refers to its unusual red flowers.

Specimens examined: INDONESIA, Sumatra, Aceh Province, Gunung Leuser National Park, Valley of Lau Alas, 17.05.1972, W.J.J.O. de Wilde & B.E.E. de Wilde - Duyfjes 12059 (K, L); Jantho Pinus Nature Reserve , Nangroe Aceh Darussalam, forest area of Sumatran Orangutan Reintroduction Program (SOCP), 12.01.2017, Nurainas & Rezi NAS-3450 (ANDA); Ketambe Research Station , 06.03.2008, P. Wilkie, M. Hughes, A. Sumadijaya, S. R a s n o v i, M a r l a n & R a b u s i n PW603 (E [E00416326!]) .

Conservation status: Cyrtandra rubriflora has been collected on three separate botanical expeditions between 1972 and 2017. Three of the four collections were made close together in Gunung Leuser National Park which straddles the borders of Aceh and North Sumatra provinces. The fourth collection is from Pinus Jantho Nature Reserve which is approximately 275 km to the north. The species has an EOO of 658 km 2 and an AOO of 12 km 2 based on a 2 × 2 km grid cell size under the B criteria ( Bachman et al., 2011). The flora of the region is relatively poorly known and it is possible that further collecting will expand the range of C. rubriflora . The threat of habitat loss in the forest regions of Sumatra, however, is well documented and is particularly acute for lowland species. One estimate indicates that the island has lost nearly half of its forests in the past 15 years alone and it seems that designation of protected areas has not been totally successful in preventing logging and deforestation within their boundaries ( Gaveau et al., 2009, Global Conservation, 2017). Three collections were made in Gunung Leuser National Park which is known to be suffering from forest degradation and loss of habitat through illegal logging and encroachment. Areas adjacent to the park have been extensively cleared for palm oil plantations ( UNESCO, 2012). It can therefore be considered likely that the habitat of C. rubriflora is threatened. Based on the small number of collections and our knowledge of the widespread deforestation and forest conversion in the area we would recommend a cautious listing for this species under Near Threatened (NT) as per guidelines for using IUCN Red list categories and criteria (2019) and emphasise the need for further collecting in the area.

Notes: Cyrtandra rubriflora is similar to the widespread and morphologically variable species C. picta but there are important differences that allow these two species to be easily distinguished and that are detailed in the diagnosis. Red-flowered species are unusual in Cyrtandra , especially in western Malesia where the majority of species have white flowers (Bramley & Cronk, 2003; Bramley et al., 2004; Atkins et al., 2013). There are only three other species from Sumatra that are described as having purplish or reddish flowers. They are all very distinct from C. rubriflora ; C. frutescens Jack and C. rubiginosa Jack have cylindrical fruits and small, linear inflorescence bracts and C. rosea Ridl. can be distinguished by being a woody shrub with smaller flowers ( 20 mm long as opposed to 43–50 mm long), decurrent leaf bases and a hairy ovary.