Croton maasii Riina & P.E.Berry, 2011

Riina, R. & Berry, P. E., 2011, Croton maasii (Euphorbiaceae), a new species from the western Amazon region, Blumea 56 (2), pp. 146-148 : 146

Croton maasii Riina & P.E.Berry , sp. nov. — Fig. 1a , 2a, b

Ab Croton pachypodae G.L.Webster capsulis minoribus,marginibus foliorum glandularis, et glandulis petiolaris aequalis differt. — Typus: P. J. M. Maas, K. Kubitzki, W. C. Steward , J. F. Ramos , W. S. Pinheiro & J. F. Lima P12775 (holo NY;iso MICH), Brazil, Acre, Cruzeiro do Sul , Estrada Alemanha,forest on terra firme, 7 May 1971 .

Etymology. The epithet honours the collector of the type specimen, Paul J.M. Maas, an authority on several tropical families like Annonaceae , Cannaceae , and Gentianaceae .

Monoecious trees 5–6 m tall; young branches with a dense, light yellowish indumentum of lepidote trichomes. Stipules linear-lanceolate, 2–3 mm long, sometimes slightly branching

1 University of Michigan Herbarium and Department of Ecology and Evo- lutionary Biology , 3600 Varsity Drive, Ann Arbor, MI 48108 , USA; e-mail: [e-mail]; corresponding author e-mail: [e-mail] .

2 Real Jardín Botánico, CSIC, Plaza de Murillo 2, 28014 Madrid, Spain .

with a glandular tip. Leaves alternate, the blades elliptic, 7–15 by 2.5–6.5 cm, apex acute, sometimes slightly acuminate, base acute, rarely rounded, margin entire or more or less sinuous, with sessile discoid glands on each sinus, mature blades glabrescent with a few scattered lepidote trichomes; venation pinnate, secondary veins 7–10, primary and secondary veins raised on both surfaces; petiolar glands patelliform, incon- spicuous, sessile, epipetiolar, adaxial, sometimes difficult to see because of the dense lepidote indumentum, on the same plane; petioles 0.7–1.6 cm long, deeply canaliculate on the adaxial side, densely lepidote. Inflorescences terminal and axillary, erect, 10–20 cm long, rachis angular, densely lepidote; bracts triangular lanceolate, 0.9–1.3 by 0.3–0.5 mm. Staminate flowers (in bud) lepidote, receptacle pilose, stamens 9. Pistillate flowers with a thick pedicel 4–9 by 1.8–2 mm; sepals 5, valvate, triangular, acute, 1.9–2 by 1.5–1.6 mm, externally densely lepidote, internally glabrous; petals lacking or reduced to a filament with an apical gland; ovary densely golden-lepi- dote, styles bifid, glabrous. Capsules globose, 1–1.3 by 1–1.3 cm; columella 1.1 cm long; seeds obovoid; 1–1.2 by 0.6–0.7 cm, mottled with grey spots on a brown background, rounded dorsally, ridged ventrally along the central axis; caruncle ovoid, 2 by 1.8 mm.

Distribution & Habitat — The species is known from extreme western Amazonian Brazil (Acre) and adjacent Peru (Loreto), where it grows in terra firme forest at low elevations, 120– 130 m.

Additional specimens examined. BRAZIL, Acre, Município Cruzeiro do Sul , BR 364 , Km from Cruzeiro do Sul to Tarauacá, linha no. 01, 13 Sept. 1985, A . Rosas Jr., J. L dos Santos, D. Campbell & D. Coelho 288 ( INPA, MICH, MPEG, NY) .– PERU, Loreto, Maynas, Distrito Fernando Lores,caserío Constancia (Quebrada Tamshiyacu), 04°08'S, 72°55'W, 120–130 m, 8 May 1991, C . Grández, J . Ruiz & J . Jaramillo 2532 ( COL, MO) .

Note — Croton maasii is similar to C. pachypodus ( Webster & Huft 1988) and C. diasii ( Secco et al. 2001) , which belong to an early diverging clade in the Croton phylogeny ( Van Ee et al. 2008, Riina et al. 2009). Croton maasii , C. pachypodus ( Fig. 1b , 2c–f ), and C. diasii have similar lepidote indumentum with a glabrous adaxial leaf surface, two epipetiolar glands in the adaxial position (sometimes visible from the abaxial side), linear-lanceolate stipules with tiny branches and glandular tips, 147

Figures

Fig.1 a. Croton maasii Riina & P.E. Berry. Image of the holotype.— b. C. pachypodus G.L.Webster. Image of the holotype,from Tropicos,botanical information system at the Missouri Botanical Garden, www.tropicos.org. — c. C. tessmannii Mansf. Image of isotype, from the C. V. Starr Virtual Herbarium (http://sciweb. nybg.org/science2/vii2.asp). (a: Maas et al. P12775, NY; b: Nevera & Herrera 3980, MO; c: Tessmann 3438, NY).

Fig. 2 a, b. Croton maasii Riina & P.E.Berry. a. Detail of the inflorescence with flowers in bud;b. inflores- cences with mature fruits and a young pistillate flower at the base. — c–f. C. pachypodus G.L.Webster. c. Abaxial view of petiolar glands from a young leaf; d. adaxial view of petiolar glands from an old leaf; e. young pistillate flowers; f. fresh, nearly mature fruits (a: Maas et al. P12775, NY; b: Grández et al. 2532, MO; c, e: Foster 11858, LPB; d: Villavicencio 1227, LPB; f: Avila AA1005, UDBC). — Scale bars: a, b, e, f = 1 cm; c, d = 1 mm.