Croton gageianus P.T.Li, 1994

Beyer, J., Esser, H. - J., Eurlings, M. C. M. & Welzen, P. C. van, 2023, A revision of the genus Croton (Euphorbiaceae) in Sumatra (Indonesia), Blumea 68 (1), pp. 1-25 : 14

7. Croton gageianus P.T.Li

Croton gageianus P.T. Li (1994) 131. — Croton lucidus Gage (1922) 236, nom.illeg.,non L. (1759, ‘ lucidum ’). — Lectotype (indirectly designated by Li 1994 as holotype, here the second lectotypification of the sheet): Ridley 12176 (lecto K [K000959158]*; isolecto SING!), Malay Peninsula, Johor, Gunong Pulai. Other syntype: Ridley 12194 (SING!), Malay Peninsula, Johor, Gunong Pulai.

Shrubs or treelets, to 5 m tall, young branchlets densely pubescent, soon glabrescent. Indumentum consisting of only whitish hyaline stellate trichomes, with a yellowish centre, 0.4–0.9 mm diam on leaves, 0.2–0.7 mm diam on stems and inflorescences, flat, with a short central porrect radius, with (11–)15–25(–30) free radii. Stipules triangular-ovate, c. 1.1 by 0.4 mm long, densely pubescent on both sides, caducous and usually absent. Leaves pseudo-verticillate; petiole 0.5–2(–3.5) cm long, deeply grooved above, subglabrous to densely pubescent; glands as slightly stalked discs lateral on the midrib base, diam 0.3–0.7 mm, stalk 0.1–0.3 mm long; blade narrowly elliptic, 7–25 by 2–5.5 cm, (3.1–)3.4–5.2 times longer than wide, membranous, base attenuate with very base often obtuse to rounded,margin (sub)entire, apex acute to acuminate, adaxial side glabrous, abaxial side slightly to densely pubescent but with surface always visible between the trichomes; venation distinct, sunken above, not to indistinctly triplinerved, secondary veins 6 –8 pairs, higher order nerves often hard to see especially on abaxial side. Inflorescences 1(–3) per node, 3–5.5 cm long, erect, slightly pubescent all over, basally 1–3 pistillate flowers, apically 1–2 staminate flowers; bracts triangular-ovate c. 0.5 by 0.5 mm, slightly pubescent on both sides, soon caducous. Staminate flowers c. 3 mm diam; pedicel 1–2 mm long, round, densely pubescent; sepals elliptic, c. 1.8 by 0.8 mm, outside densely pubescent, inside glabrous; petals elliptic, c. 1.4 by 0.4 mm, outside glabrous, inside lanate; stamens c. 11, immature. Pistillate flowers c. 3 mm diam; pedicel c. 2 mm long, sulcate, densely pubescent; sepals triangular-ovate, c. 2 by 1 mm, longer than ovary, outside densely pubescent, inside glabrous; petals absent; ovary globose, c. 1.3 by 1.3 mm long, slightly sulcate, densely yellowish hispid; style absent; stigmas c. 3 mm long, once divided to c. 2.5 mm from apex, glabrous. Capsules globose, c. 5 by 6 mm, slightly sulcate, with scattered trichomes; pericarp c. 0.5 mm thick; columella 4–5 mm long. Seeds globose to slightly obovoid, c. 5 by 4 mm, glabrous, with a small caruncle.

Distribution — Malesia: Malay Peninsula, Sumatra (Atjeh, Sumatera Barat, Bengkulu).

Habitat & Ecology — In primary lowland (Dipterocarp) rain- forest, found on ridges and alluvial soil. Altitude: 100– 700 m. Flowering: June; fruiting: February.

Affinities — Riau pocket group ( Van Ee et al. 2015), part of a polytomy ( Fig. 1 : group I 4), thus close affinities are unknown.

Notes — 1. Gage (1922) made a later homonym for a Linne- an name ( Linnaeus 1759) and mentioned two syntypes, Ridley 12176 and Ridley 12194 (SING). Li (1994) restored the error by using a new name. He regarded Ridley 12176 as the holotype, thus indirectly creating a lectotype.

2. Only six specimens (of which one as uncertain) were seen, of them only one specimen had a pistillate flower, one with a fruit, one with seed and one with an almost matured staminate flower, which was too fragile to measure the stamens.

3. Outside L only known from three collections, of which two collections are named by Gage (1922) and Li (1994), Ridley 12176 & 12194, both from the Malay Peninsula, Johor, Gunong Pulai. Besides these two Ridley collections there are also Sinclair 7277 (E [E00201750]*, US [01246063]*) and Sinclair SFN 39510 (SING*), Malay Peninsula, Gunong Pulai (summit). The specimen at US is incorrectly placed under Croton lucidus L. (in error for C. lucidus Gage ).

Figures

Fig. 1 Bayesian phylogram based on ITS sequences excluding the 5.8S region. The values at nodes represent the Bayesian-inference posterior-probability support values. Astraea and Brasiliocroton are outgroups. Black names: New World, yellowish brown: Africa–Madagascar, green: mainland Asia, blue: Aus- tralia–West Pacific,red: Malesia.Accessions with bold names correspond to the newly sequenced taxa, all ocurring in Sumatra. Bar: nucleotide substitutions.