Croton tsiampiensis Leandri
Creators: name: Kainulainen, Kent
name: Ee, Benjamin van
name: Razafindraibe, Hanta
name: Berry, Paul E.
Publisher: name: Zenodo
Year: 2017
Subjects: Biodiversity
Taxonomy
Plantae
Tracheophyta
Magnoliopsida
Malpighiales
Euphorbiaceae
Croton
Croton tsiampiensis

description: Croton tsiampiensis Leandri in Ann. Mus. Colon. Marseille, sér. 5, 7: 79. 1939. (Fig. 1I, 2B, 4 O-P, 13).
Lectotypus (designated here): MADAGASCAR. Prov. Mahajanga: Tsiampihy, près de l’embouchure de la Soahanina, 15.X.1932, Leandri 311 (P [P00389521]!; isolecto-: P [P00133302]!).
= Croton tsiampiensis var. ankaranensis Radcl.-Sm., Gen. Croton Madag. Comoro 110. 2016. Typus: MADAGASCAR. Prov. Antsiranana: Diana Reg., Massif de l’Ankarana, 4.XI.1990, Bardot-Vaucoulon 224 (holo-: P [P00123706]!), syn. nov.
= Croton tsiampiensis var. macrophyllus Radcl.-Sm., Gen. Croton Madag. Comoro 110. 2016. Typus: MADAGASCAR. Prov. Mahajanga: Reserve Naturelle Bemaraha, Ambodiriana, c. 9 km E of Antsalova, 18º39’S 44º43’E, 100-125 m, 13-15.XII.1990, Gillespie 4139 (holo-: K!; iso-: MICH!, MO), syn. nov.
= Croton tsiampiensis var. microphyllus Radcl.-Sm., Gen. Croton Madag. Comoro 111. 2016. Typus: MADAGASCAR. Prov. Antsiranana: Diana Reg., P.K. 10 de la route Diego Suarez-Orangea, 13.XII.1963, Service Forestier 22956 (holo-: P [P00123706]!), syn. nov.
Shrubs or trees 2-6 m tall, dichotomously branching, internodes sometimes so short as to give the appearance of whorled branches; in all parts covered in whitish to ferrugineous, stellate trichomes many of which have a bristly, porrect (to c. 4 mm) central radius. Branches flattened on new growth but becoming terete with age, green at first, soon turning a matte pale gray (to reddish brown); red latex present in freshly cut stems. Stipules 8-30 × 1-5 mm, lanceolate, entire or incised, with marginal glands, caducous. Leaves deciduous, opposite. Petioles 1.2-12 cm long, adaxially canaliculate, stellatepubescent, usually with a pair of acropetiolar, ± stipitate glands with a concave, discoid, yellow apex (0.5-1 mm diam.). Leaf blades membranaceous to papyraceous, glandular-denticulate, broadly ovate to suborbicular, 3-18 × 3-15 cm, apex acuminate, base rounded to cordate; abaxially and adaxially conspicuously hirsute, pale green when fresh and drying matte pale green to brown; venation evident on both sides, prominent below, with 5-9 pairs of brochidodromus, ± penninerved secondary veins (the lowermost pairs congested and appearing palmate), and cross-venulate tertiary venation; with ± stipitate glands in some of the axils of the secondary veins (Fig. 1I). Inflorescences terminal, raceme-like thryses 5-20 cm long, with pistillate flowers toward the base and staminate flowers towards the distal end, axes stellate, flattened; bracts triangular, 1.0- 2.5 mm long, caducous. Staminate flowers with stellate, subglobose buds 1.5-2.9 mm diam., pedicels 1-3 mm long; sepals 5, shortly connate at base, lobes ovate, c. 2 × 1.2 mm, apex acute, inflexed at anthesis, abaxially stellate, adaxially glabrous, margins ciliate; petals 5, white, elliptic-spatulate, 2.5-2.7 × 1-1.5 mm, recurved at anthesis, abaxially subglabrous and papillose, adaxially glabrous, margins ciliate; disc glands 5, opposite the sepals, sessile, ellipsoidal with an apical depression, c. 0.4 × 0.3- 0.6 mm, yellowish; stamens 12-15, white, filaments 1.5- 3.3 mm long, glabrous or pilose at base, anthers broadly elliptic, c. 0.5-1 × 0.5-0.8 mm; receptacle pilose. Pistillate flowers with stellate, ellipsoid buds c. 2.2 mm diam., pedicels 1-4 mm long; sepals 5, ovate, spreading at anthesis, 2.5-3 × 1.3- 2.3 mm, apex acute, shortly connate at base, abaxially stellate, adaxially glabrous except towards the apex, persistent in fruit; petals often reduced, 0.8-2.5 2.5 × 0.2-1 mm, linear to spathulate, recurved, glabrous but with a ciliate margin; disc glands 5, opposite the sepals, sessile, ellipsoidal, c. 0.4 × 0.8 mm; ovary densely hirsute, globoid, 1.5-3.7 mm diam; styles 3, 3- 4.2 mm long, each branch flattened and 2-3 times bifurcate, spreading, abaxially stellate, adaxially glabrous, persistent. Capsules 4-8 × 5-8 mm, densely hirsute, exocarp not separating (Fig. 4O), endocarp woody, 0.4-0.6 mm thick; columella 3.5-5.5 mm long, cornute, capitate. Seeds ±compressed-ellipsoid, 3.5-5.6 × 3-4.3 × 2-2.9 mm (Fig. 4P); testa glossy, verrucose, brown; caruncle narrowly reniform c. 0.7 × 2 mm.
Phenology. – This species has been collected only from October to March, presumably because it is deciduous during the remaining drier months of the year. Specimens in flower have been collected from October to February, and in fruit from October to January.
Distribution, habitat and ecology. – Croton tsiampiensis has a disjunct distribution in northern Antsiranana and southern Mahajanga Provinces, respectively (Fig. 2B). It has been collected in deciduous, semideciduous, and evergreen forests, as well as in anthropogenic savannas, at 45-500 m in elevation, on sandy substrates and on tsingy limestone.
Conservation assessment. – This species appears to be widespread with fragmented populations in deciduous forests of northern and western Madagascar, including the the protected areas Ankarana, Beanka, Bemaraha, and Daraina. We therefore treat this species as “Near Threatened” [NT] according the IUCN Red List Categories and Criteria (IUCN, 2012).
Notes. – The species epithet tsiampiensis refers to the type locality, the Tsiampihy forest in Mahajanga Province.
Croton tsiampiensis is distinct for its broadly cordate leaves, large incised stipules, and very hirsute pubescence. It is superficially similar to C. ankarensis Leandri, and Leandri’s description of that species was likely based on specimens representing different taxa, one of which is likely C. tsiampiensis. The type of C. ankarensis, Perrier de la Bâthie 9830 from Ankara (Betsiboka Reg.), lacks laminar glands and has alternate leaves, as well as sparsely stellate-pubescent capsules. It is clearly different from C. tsiampiensis and does not belong in the Adenophorus Group (it was placed in the Ankarensis Group by LEANDRI, 1939). The Leandri 103bis syntype from Bemaraha is nearly leafless, but the leaf scars are opposite. The pistillate flowers are much larger than in Perrier de la Bâthie 9830, but they conform to C. tsiampiensis, as does the markedly hirsute and pale gray bark of the young branches. We therefore tentatively include Leandri 103bis in C. tsiampiensis.
The varieties C. tsiampiensis var. macrophyllus and var. microphyllus that RADCLIFFE-SMITH (2016) described based on differences in leaf size are synonymized here. As with many of the new names in his manuscript, only single specimens are cited, and from our studies of a broader sample of specimens that are now available, it is evident that more variation in leaf size is found within, rather than between, populations. Nor is it meaningful to recognize C. tsiampiensis var. ankarensis, which RADCLIFFE-SMITH (2016) distinguished from the type variety by its shorter petioles (<1 cm vs> 1.5 cm) and inflorescences, as well as slightly larger fruits. We have collected large-leaved specimens (van Ee et al. 2371) from the Ankarana population with leaves up to 16 × 11 cm and petioles up to 11 cm long, and Gillespie et al. 10696, also from Ankarana, is closer in inflorescence length and fruit size to the type of C. tsiampiensis than to C. var. ankarensis. There are currently no vernacular names recorded for Croton tsiampiensis.
Additional specimens examined. – MADAGASCAR. Prov. Antsiranana: Diana Reg., Ankarongana, Analafandro, 12°37’50”S 49°31’28”E, 46 m, 23.II.2006, Andrianjafy et al. 1619 (CNARP, MICH, MO, P, TAN); Ankarana, 13.X.1990, Bardot-Vaucoulon 131 (P); ibid. loc., 4.XI.1990, Bardot-Vaucoulon 224 (P); ibid. loc., 12°55’S 49°05’E, 150 m, 5.XI.1990, Bardot-Vaucoulon 252 (P, TAN); ibid. loc., 19.I.1991, Bardot-Vaucoulon 392 (P); ibid. loc., 200 m, 3.II.1960, Cours & Humbert 5614 (P); ibid. loc., 12°54’S 49°07’E, 150 m, 29.XI.1990, Gillespie 4085 (MICH, MO); ibid. loc., 12°55’23”S 49°05’09”E, 110 m, 2.XI.2012, Gillespie et al. 10696 (CAN, MICH, MO, TAN); ibid. loc., 30-350 m, 24.I-29.II.1960, Humbert 32654 (P); SAVA Reg., Vohemar Distr., Daraina, Antsahabe forest, 13°12’37”S 49°33’27”E, 520 m, 11.I.2004, Nusbaumer 902 (G, MICH, MO, P); ibid. loc., 13°12’36”S 49°33’43”E, 500 m, 21.I.2004, Nusbaumer 1076 (G, MICH, MO); ibid. loc., 13°12’35”S 49°33’38”E, 500 m, 5.XI.2006, Randrianaivo et al.1400 (CNARP, MICH, MO, P, TAN); Ankarana National Park, Maeva trail, 12°57’23 “S 49°07’04”E, 128 m, 6.III.2016, van Ee et al. 2370 (MICH, TAN); ibid. loc., 12°57’23 “S 49°07’00”E, 153 m, 6.III.2016, van Ee et al. 2371 (MICH, TAN); ibid. loc., Benavony trail, 12°56’55 “S 49°07’39”E, 124 m, 7.III.2016, van Ee et al. 2378 (MICH, TAN). Prov. Mahajanga: Melaky Reg., collines au N d’Antsalova, bord de la Soahanina, 18.X.1932, Leandri 281 (K, P, TAN); ibid loc., Leandri 283 (P); Beanka, partie S, Ambinda-Est, 18°02’41 “S 44°30’08”E, 261 m, 24.XI.2011, Gautier & Tahinarivony 5718 (G, MO); Tsingy du Bemaraha, 4.X.1932, Leandri 103bis (K, P); Beanka, partie S; Ambinda-Est, 18°02’59”S 44°30’17”E, 260 m, 11.XII.2011, Nusbaumer et al. 3051 (G, MICH).
description: Published as part of Kainulainen, Kent, Ee, Benjamin van, Razafindraibe, Hanta & Berry, Paul E., 2017, A revision of the Adenophorus Group and other glandular-leaved species of Croton (Euphorbiaceae) from northern Madagascar and Mayotte, including three new species, pp. 371-402 in Candollea 72 (2) on pages 399-401, DOI: 10.15553/c2017v722a15, http://zenodo.org/record/5722061