Croton micans Swartz (1800: 1185)

Rossine, Yuri, Melo, André Laurênio De, Athiê-Souza, Sarah Maria & Sales, Margareth Ferreira De, 2023, Understanding the “ Marmeleiros ”: a taxonomic treatment of Croton sect. Lasiogyne (Euphorbiaceae) in Brazil, Phytotaxa 584 (4), pp. 219-250 : 237-238

8. Croton micans Swartz (1800: 1185) .

Lectotype (designated by van Ee & Berry 2009): Without locality, without date, O. Swartz s.n. ( S [ S06-20998 !]) . Fig. 7 (f–k), 9 (a)

Croton bixoides Vahl (1807: 53) .— Oxydectes bixoides (Vahl) Kuntze (1891: 610) . Holotype:— MARTINIQUE: “ Habitat in America , in herb. Jussieui ”, without date, without collector (P [ P00623616 !]).

Croton choristolepis Urban (1919: 407) .— Holotype: TRINIDAD & TOBAGO. Trinidad : without locality, without date, K. Finlay n. 2440 (NY [ NY00246526 !]).

Croton helicoideus M̧ller Argoviensis (1865: 97) .— Lectotype (designated by van Ee & Berry 2009): VENEZUELA. Carabobo: 1845– 1846, N. Funck & L. J. Schlim 563 (BR [BR 0000006998820!]; isolectotypes: BM [BM000926614!], W [W98538!], fragment at F [F00 56136F!]).

Description: —Monoecious shrub to small tree, 2–5 m tall; latex not seen; branching monopodial, branches cylindrical, slightly striated, brown to greyish; trichomes stellate-lepidote to dentate-lepidote. Leaves alternate; stipules helicoidal, auriculate 0.2–0.7 × 0.1–0.8 cm, usually deciduous, with lepidote trichomes; petiole cylindrical, 0.5–1.5 cm long, with lepidote trichomes; leaf blade chartaceous, ovate, 2–7.5 × 1–4 cm, strongly bifacial, adaxial face dark green with dentate-lepidote to lepidote trichomes, abaxial face shiny, light green to silver, with lepidote trichomes, base rounded to cordate, margins entire, apex acute, venation actinodromous perfectly reticulate. Thyrses 3–10 cm long, terminal, with lepidote trichomes, peduncle ca. 0.5 cm long; cymules unisexual, lax, solitary flowers; bracts deciduous, elliptic, 1–3.5 × 0.5–1 mm, margins entire, apex acute, with lepidote trichomes. Staminate flower with pedicels 1–5 mm long; sepals silvery, united for ⅓ of their length, lobes ovate, 2–3 × 1–2 mm, margins entire, apex acute, lepidote trichomes externally, glabrescent internally; petals white, oblong, 2–3.5 × 1–1.5 mm, margins entire, apex rounded, with lepidote trichomes externally, stellate-lepidote trichomes internally; stamens 13–14, filament 3–4.5 mm long, anther long elliptic, ca. 1 × 0.8 mm; nectary disk of 5 free segments, elliptic, glabrous. Pistillate flower with pedicels 1–2 mm long; sepals green to silver, united for ⅟ 4 of their length, lobes ovate to long ovate, equal in size, 2–3 × 1.5–4 mm, reduplicated vertical and horizontally, margins entire, apex acute, with lepidote trichomes externally and internally; petals absent; ovary long ovoid to obloid, 1–2.5 × 2–2.8 mm, with lepidote trichomes; styles ascending, free, sometimes slightly united at the base, 4-partite to multipartite, 12–18 stigmatic tips, with lepidote trichomes; 5- lobed nectary disk, apex of lobes rounded, with lepidote trichomes. Capsule green silvery, obloid, 3–5 × 4–5.8 mm, 3- lobed, surface non-muricate, with lepidote trichomes; columella ca. 2.5 mm long, striated, apex flattened. Seed brown, ovoid, 2.6–3.0 × 2.2–2.5 mm, smooth, caruncle not seen.

Vernacular names: — Not found.

Distribution and habitat, conservation status, and phenology: — Croton micans can be found in the Antilles, Bolivia, Colombia, Ecuador, Trinidad and Tobago, and Venezuela ( Gomes 2006, van Ee & Berry 2009, Luján et al. 2015). We confirmed the occurrence of C. micans in Brazil, occurring in the Pantanal domain in areas of dry vegetation and roadsides in Mato Grosso do Sul ( Fig. 9 , a). It is commonly found in calcareous soils. Although with fragmented populations and an AOO of 228 km 2, Croton micans is classified here as of least concern (LC) because it has a wide EOO (> 7,500,000 km 2) and is cultivated in many localities of other South American countries. On the other hand, populations in Brazil are scarce, and the species is not found in protected areas, but rather in areas that have been frequently impacted by anthropic actions. Flowering and fruiting from May to November.

Notes: — Croton micans is easily distinguished from other species of section Lasiogyne in Brazil by being the only species to present a leaf blade with silvery lepidote trichomes on both surfaces, actinodromous perfectly reticulate venation, the base sometimes recurved ( Fig. 7 , g), and helicoidal auriculate stipules.

Representative specimens: — BRAZIL. Mato Grosso do Sul: Corumbá , 17 October 1984, C. A . Conceição 1640 ( CEN); ibid, base do Cerro do Urucum, 23 km S de Corumbá , 22 November 1977, A. C . Allem 1458 ( CEN) .

Figures

FIGURE 7. a–e Croton limae: a flowering branch with monopodial ramification b narrowly lanceolate stipules, c staminate flower of 15 stamens, d pistillate flower with triangular and vertically reduplicated sepals, spheroid ovary, and ascendant and multipartite styles, e spheroid fruit. f–k C. micans: f flowering branch with monopodial ramification, g detail of the recurved leaf blade base, h auriculate helicoidal stipule, i staminate flower of ca. 13 stamens, j pistillate flower with sepals strongly reduplicated horizontally and vertically, obloid ovary, and ascendant and multipartite styles, k fruit. l–p C. sacaquinha: l flowering branch with sympodial ramification, m linear stipules, n staminate flower of 15 stamens, o pistillate flower with sepals slightly reduplicated vertically, developed petals, ovoid ovary, and ascendant and multipartite styles, p ovoid fruit, 3-lobed.

FIGURE 9. Distribution of some species of section Lasiogyne. a Croton limae, C. micans and C. sacaquinha; b C. suassunae and C. tricolor.