Cyrtandra engleri Koord., Meded. Lands Plantentuin

Atkins, H. J. & Kartonegoro, A., 2021, A TAXONOMIC REVISION OF CYRTANDRA (GESNERIACEAE) IN SULAWESI, INDONESIA, Edinburgh Journal of Botany 78 (364), pp. 1-122 : 31-33

6. Cyrtandra engleri Koord., Meded. Lands Plantentuin 19: 628 (1898).

– Type: Indonesia, Celebes [Sulawesi], Minahassa, Mt Lokon , 7 i 1895, Koorders 17204β (lectotype BO, designated here) .

Shrub or small tree to 4 m in height. Stems striate, hairy, densely so on young growth. Leaves opposite; one leaf of a pair markedly reduced or appearing alternate; petioles 6–10 mm long, densely hairy; blades of larger leaves 4.5–11 × 1.5–3 cm, oblanceolate to narrow oblong, acute at base, slightly asymmetrical, margins subentire to minutely serrulate, apex acuminate, acumen 2–5 mm long; 4 or 5 pairs of lateral veins, curving upwards and eventually running out to margin, tertiary venation reticulate, subglabrous above, sparsely hairy below, more densely so on midrib, veins and margin. Reduced leaves (where present) sessile, 2–3 mm long, cordate. Inflorescences axillary, sessile, 1- or 2-flowered; bracts 2–3 × 1 mm, linear to narrow ovate, hairy; pedicels up to 5 mm long, densely hairy. Calyx evenly 5-lobed or occasionally appearing 4-lobed where two lobes are adpressed, whitish, flushed purple below, 10–13 mm long, lobes narrow, acuminate, 5–7 mm long, densely brown-hairy. Corolla white, sometimes with purple markings in throat, 15–20 mm long, narrow in basal half, widening gradually to mouth in apical half, upper lobes rounded 3 × 2 mm, lower and lateral lobes 4 × 3 mm, densely hairy externally. Stamens with filaments 3–4 mm long, attached 7–8 mm from base of corolla, filaments glabrous; anthers c. 1 mm long, connected at tips before dehiscence, some glandular hairs on back of anthers; staminodes 3, 1 mm long, occasionally with a distinctive tuft of hairs at apex. Gynoecium 9–11 mm long; disc cupular with lobed, sparsely fringed margin, 1.5–2 mm long, glabrous; ovary and style densely eglandular hairy; stigma capitate, slightly bilobed, c. 1 mm across. Fruits oblong to narrow ovoid, 10–11 × 4 mm, densely hairy, base of style persistent, calyx not persistent.

Distribution. North Sulawesi and Gorontalo (see Figure 20 ).

Habitat and ecology. Hill and upland forest at an altitude of 600–1400 m.

Etymology. This species is presumed to be named after H. G. A. Engler, a German botanist and contemporary of Koorders.

Proposed IUCN conservation category. This species occurs in North Sulawesi and Gorontalo and has an EOO of 6412 km 2 and an AOO of 20 km 2, based on a 2 × 2 km grid cell size ( Bachman et al., 2011). All the collections are from localities between 600 and 1400 m, which includes some of the most threatened forest types on the island, due to population pressure and land conversion ( Cannon et al., 2007), and only one collection locality falls within a protected area (Mount Lokon Nature Reserve) (UNEP-WCMC & IUCN, 2019). The species has not been re-collected since 1956, despite this being one of the better-collected areas in Sulawesi. It is therefore probable that it occurs at five or fewer locations. Because of its restricted distribution, the known threat to its habitat type and the lack of protection, Cyrtandra engleri is considered to be Endangered (EN), B2ab(iii).

Additional specimens examined. INDONESIA. North Sulawesi. Bolaang Mongondow: viii 1917, Kaudern 186 (L, S) ; South Minahasa: Mt Mahawu , 21 vi 1956, Forman 185 (BO, K, L, SING) ; ibid., 23 vi 1956, Forman 224 (BO, K, L, SING) ; Tetepangan, Mt Lokon , 3 vii 1956, Forman 366 (BO, K, L) .

Gorontalo. Gorontalo: Mt Boliohutu , 24 iv 2002, Atkins et al. 209 (BO, E, L) .

Cyrtandra engleri is part of a group of six species on the island that share the characteristics of strongly anisophyllous leaves, where the smaller leaf is highly reduced; white or yellow corollas; and densely hairy calyces, corollas and fruits. The others in the group are Cyrtandra balgooyi , C. gambutensis , C. gorontaloensis , C. parvicalyx and C. widjajae .

Cyrtandra engleri is most similar to C. widjajae , a species originally described from Southeast Sulawesi ( Kartonegoro & Potter, 2014) but that also extends into North Sulawesi. It can be distinguished from Cyrtandra widjajae most easily by the smaller number of lateral vein pairs (4 or 5 in C. engleri versus 8–10 in C. widjajae ) and the short-acuminate leaf apices (2–5 mm long in C. engleri versus up to 20 mm long in C. widjajae ). Cyrtandra engleri also has a much denser, coarse indumentum and larger corollas (15–20 mm long versus 11–15 mm long), often with tufted staminodes and with dense eglandular hairs throughout the length of the style (as opposed to a transition to glandular hairs at the top of the style near the stigma in C. widjajae ). Corollas are noted, in Cyrtandra engleri , as having purple markings in the throat, but the flowers of C. widjajae are completely white.

Two collections from Mount Boliohutu in Gorontalo Province, some distance from the localities of other collections in North Sulawesi, are included here, although the leaf shape is somewhat different and the corollas lack the purple markings. Further collections are required to clarify the status of these specimens.

Koorders 17204β is selected here as the lectotype, because it was originally annotated with the name Cyrtandra engleri by Koorders.

Figures

Figure 20. Distribution of Cyrtandra engleri (black triangles), C. fasciata (red circles) and C. flavomaculata (black circles).