Croton ankeranae Kainul. 2016, spec. nova
Creators: name: Kainulainen, Kent
name: Ee, Benjamin van
name: Antilahimena, Patrice
name: Razafindraibe, Hanta
name: Berry, Paul E.
Publisher: name: Zenodo
Year: 2016
Subjects: Biodiversity
Taxonomy
Plantae
Tracheophyta
Magnoliopsida
Malpighiales
Euphorbiaceae
Croton
Croton ankeranae

description: Croton ankeranae Kainul., spec. nova (Fig. 1C, 2).
Typus: MADAGASCAR. Prov. Toamasina: Atsinanana Region, Distr. Brickaville, Commune Maroseranana, Fokontany Ambodilendemy, Andrangato River, 18°26’37”S 48°46’31”E, 446 m, 13.III.2011, Antilahimena 7554 (holo-: MICH [MICH1513200]!; iso-: MO!, P, TAN).
Croton ankeranae Kainul. can be distinguished from the similar small-leaved shrub Croton indrisilvae Kainul., B.W. van Ee & P.E. Berry by its taller habit (to 12 m vs. <1 m) and smaller leaves (4.5-10.5 × 3.9-6.3 mm vs. 9-28 × 5-12 mm) that are entire (vs. crenate) with the apex acute to obtuse (vs. obtuse to rounded).
Shrubs to small trees 0.8-12 m tall, dichotomously branching, internodes sometimes contracted giving the appearance of whorled branches. Branches ± flattened on new growth and densely covered by dark gray-brown fasciculate trichomes with rays c. 0.2 mm long, pale gray to whitish, becoming terete and glabrous with age. Stipules absent or vestigial. Leaves subopposite, ± congested at nodes. Petioles 0.7-1.8 mm, adaxially canaliculate, sometimes with a pair of acropetiolar, stipitate (0.2-0.4 mm long), discoid (c. 1.5 mm diam.) glands. Leaf blades thinly coriaceous, entire, (broadly) elliptic to obovate, 4.5-10.5 × 3.9-6.3 mm, apex acute-obtuse, base cuneate; adaxial surface glabrous, glossy, dark green when fresh and drying dark green; secondary venation indistinct; abaxial surface sparsely fasciculate, pale green when fresh and drying pale brown; secondary venation indistinct, midrib prominent. Inflorescences comprising 1-2 staminate flowers or a solitary pistillate flower, axillary or terminal; bracts triangular, c. 3.0 × 0.2 mm. Staminate flowers with fasciculate, subglobose buds c. 0.9 mm diam., pedicels to 1.5 mm long; sepals 5, shortly connate at base, lobes triangular to ovate, c. 0.7 × 0.3 mm, apex acute, inflexed at anthesis, abaxially fasciculate, adaxially glabrous, margins densely ciliate, pale green; petals 5, white, narrowly obovate to spatulate, c. 1.0 × 0.2 mm, recurved at anthesis, abaxially sparsely papillate, adaxially glabrous, margins densely ciliate; disc glands/nectaries 5, opposite the sepals, sessile, ellipsoid, c. 0.1 × 0.05 mm; stamens 3-5, white, filaments c. 1.5 mm long, ciliate, anthers broadly elliptic, c. 0.2 mm long; receptacle pilose. Pistillate flowers with fasciculate-pubescent buds c. 0.9 mm diam., pedicels 0.5- 0.9 mm long; sepals 5, elliptic, spreading at anthesis, 1.2 × 0.6 mm, apex rounded, abaxially stellate-pubescent, abaxially sparsely fasciculate, pale green; disc glands/nectaries 5, opposite the sepals, sessile, ellipsoid, c. 0.3 × 0.2 mm; glandular filaments (in petal position alternating with the nectary lobes) 5, linear, c. 0.5 × 0.07 mm, erect; ovary globose, c. 0.8 mm diam., densely stellate, styles 3, c. 2.5 mm long, bifurcate, spreading, recurved at the apices, with some fasciculate trichomes and a few pilose trichomes at the base, white, turning brown, persistent. Capsules 3-4 × 6-7 mm, smooth, with fasciculate trichomes; columella 2.8-3.5 mm long, cornute, capitate. Seeds not seen.
Etymology. – The specific epithet refers to the Ankerana forest where this species is found.
Distribution, Habitat and Ecology. – Croton ankeranae is to date only known from the Ankerana-Vohimanana montane forest in the Antsinanana Region of Toamasina Prov., at 400- 1050 m elevation (Fig. 1C).
Notes. – This species is probably most closely related to C. indrisilvae Kainul., B.W. van Ee & P.E. Berry described below, which has similar whitish stems with brown-fasciculate pubescence, small leaves with indistinct venation, and reduced inflorescences. However, both the leaves and flowers of C. ankeranae are smaller and among the smallest of any Malagasy Croton, and the staminate flowers have only 3 to 5 stamens.
Paratypi. – MADAGASCAR. Prov. Toamasina: Atsinanana Region. Brickaville Distr., Anjahamamy, Anivoranokely, Ankerana forest, 18°24’46”S 48°49’24”E, 768 m, 28.I.2012, Antilahimena 8108 (MO, P, TAN); Maroseranana, Ambodilendemy, piste vers Vohimanana, 18°25’08”S 48°47’20”E, 1011 m, 24.III.2011, Ravelonarivo et al. 3838 (MICH, MO); Ambatolampy, Vohimanana forest, 18°24’05”S 48°48’43”E, 927 m, 19.I.2012, Ravelonarivo & Edmond 4082 (MICH, MO, P, TAN); Ankerana forest, 18°25’42”S 48°48’38”E, 695 m, X.2005, Razakamalala et al. 2260 (MO, P, TAN).
description: Published as part of Kainulainen, Kent, Ee, Benjamin van, Antilahimena, Patrice, Razafindraibe, Hanta & Berry, Paul E., 2016, New species and species reports of Croton L. (Euphorbiaceae) from the eastern forest corridor of Madagascar, pp. 327-356 in Candollea 71 (2) on pages 329-331, DOI: 10.15553/c2016v712a17, http://zenodo.org/record/5721805