Croton argyrophyllus Kunth, Bonpland & Humboldt (1817: 68)

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 : 227-231

1. Croton argyrophyllus Kunth, Bonpland & Humboldt (1817: 68) .

— C. micans var. argyrophyllus (Kunth, Bonpland & Humboldt) M̧ller Argoviensis (1866: 554) .

Holotype:— VENEZUELA. Sucre: Manicuare , 1800, A.J.A. von Humboldt & F.W.H.A. Bonpland 1217 ( P [ P00669843 !]; isotype: B [ B-W17899-010 !]) . Fig. 4 (a–e); 6 (a)

Croton nervosus var. villosus Klotzsch (1843b: 50) .— C. argyrophyllus var. villosus (Klotzsch) M̧ller Argoviensis (1865: 96) . Lectotype (designated by Rossine et al. 2021):— GUYANA: “On the Essequibo”, without date, R.H. Schomburgk 44 (G [G00434603!]; isolectotypes: E [E00164720!], G [G00434602!, G311384!], K [K000253587!, K000253589!]).

Croton argyroglossus Baillon (1864: 290) . — C. micans var. argyroglossus (Baillon) M̧ller Argoviensis (1873: 122) . Lectotype (designated by Rossine et al. 2021):— BRAZIL. Bahia: Jacobina, 1845, J.S. Blanchet 3655 (P [P00623634!]; isolectotypes: A [A00257884!], BR [BR0000008553249!], F [F0056105F!], FI [FI011642!], G [G00434465!, G00434464!], K [K000185987!], P [P00623633!]).

Croton milleri Johnston (1905: 690) . Lectotype (designated by Rossine et al. 2021):— VENEZUELA. Nueva Esparta: Isla de Margarita, El Valle, 10August 1903, J.R. Johnston 48 (GH [GH00047196!]; isolectotypes:K [K000574059!], M [M0242067!], NY [NY00262922!], US [ US 01050279!]).

Croton schomburgkianus A. P. S. Gomes & M. F. Sales (2010: 907) .— Croton argyrophyllus var. pubescens (Klotzsch) M̧ller Argoviensis (1865: 96) .— Croton micans var. pubescens M̧ller Argoviensis (1866: 554) .— Croton nervosus Klotzsch (1843: 50) . nom. illeg.— Croton nervosus var. pubescens Klotzsch (1843: 50) . Lectotype (designated by Gomes et al. 2010):— GUYANA: “in Guyana anglica secus Essequibo”, 1837, R. H. Schomburgk 802 (K [K000185986!]; isolectotypes: K [K000185985!], A [A00047359!], 2x F [F0056106F!], G [G00434601!], P [P00634523!], US [ US 00109626!]).

Description: —Monoecious shrub, 1–4 m tall; latex yellow; branching sympodial, branches cylindrical, slightly striated, brown to greyish; trichomes stellate-lepidote. Leaves alternate; stipules linear to lanceolate, 4–5 × 0.1–0.6 mm long, usually deciduous, with stellate-lepidote trichomes; petiole cylindrical, 0.4–1 cm long, with stellate-lepidote trichomes; leaf blade chartaceous, lanceolate to elliptic, 3–9 × 1–3.5 cm, strongly bifacial, adaxial face light green to dark green with stellate to stellate-lepidote trichomes, sometimes dentate-lepidote to lepidote, abaxial face shiny, silvery to yellowish, with stellate-lepidote to dentate-lepidote trichomes, rarely stellate-porrect, base rounded to slightly cordate, margins entire, apex acute, acuminate or rounded, rarely mucronate, venation eucamptodromous, with 6–14 secondary veins. Thyrses 5–15 cm long, terminal, with stellate-lepidote to dentate-lepidote trichomes, cymules unisexual, peduncle 0.5–1 cm long; cymules lax, solitary flowers; bracts deciduous, lanceolate, sometimes 3- lobed, two lateral lobes smaller inconspicuous, 2–3.5 × 0.5–1.5 mm, margins entire, apex acute, with stellate-lepidote trichomes. Staminate flower with pedicel 1–3.5 mm long; sepals silver, united for ⅓ of their length, lobes triangular to ovate, 2–3 × 1–2 mm, margins entire, apex acute, with lepidote trichomes externally, glabrous internally; petals white, lanceolate, 3–3.5 × 1 mm, margins entire, apex acute, trichomes simple; stamens 12–18, filament 2–3.5 mm long, anther long ovate, 1 × 0.8 mm; nectary disk 5-partite, apex of lobes rounded, with lepidote trichomes. Pistillate flower with pedicel 1–2 mm long; sepals greenish to silver, united up to ⅓ of their length, lobes ovate, equal in size, 3–6 × 2–4 mm, reduplicated vertically and horizontally, margins entire, apex acute, trichomes lepidote externally, stellate-lepidote to glabrescent internally; petals absent; ovary long ovoid, 2–3 × 2 mm, with lepidote trichomes; styles ascending, multifid, slightly united at the base, 14–18 stigmatic tips, with lepidote trichomes; nectary disk 5-lobed, apex of lobes rounded, with lepidote trichomes. Capsule silvery green, ovoid to obloid, 5–6.5 × 4.5–5.5, 3-lobed, surface non-muricate, with lepidote trichomes; columella up to 4.5 mm long, striated, apex flattened. Seed brown to gray, ovoid to elliptic, 4–5 × 2.8–3.2 mm, smooth, caruncle reniform.

Vernacular names: — Velame prateado, velame falso, velame mirim, sacatinga, cassatinga.

Distribution and habitat, conservation status, and phenology: —Species distributed through Brazil, Bolivia, Colombia, Paraguay, Peru, and Venezuela ( Gomes 2006, Carneiro-Torres 2009). In Brazil, it occurs in the Caatinga and Amazon domains, and more rarely in dry and anthropized areas within the Atlantic Forest domain (Caruzo et al. 2022). Their populations are always associated with xeric environments, preferentially in sandy or sandy-stony soils, more rarely in clayey soils. Up until now, it has been recorded only for Rondônia and Roraima (northern region) and all of the northeastern (Caruzo et al. 2022). The present study brings Croton argyrophyllus as a new record for Acre (northern) and Minas Gerais (southeastern) ( Fig. 6 , a), occurring in Amazonian savanna and anthropized areas. Croton argyrophyllus has a wide EOO (> 11,000,000 km 2) and an AOO of <750 km 2. Despite its AOO, this species is evaluated here as of Least Concern (LC), as it has a wide EOO and is present in several environmental protection areas. Flowering and fruiting throughout the year.

Notes: — Croton argyrophyllus can be confused with C. sacaquinha or C. tricolor due to the general appearance of its lanceolate leaves with a shiny abaxial surface. It can, however, be easily distinguished by its total lack of the ferruginous trichomes seen on C. sacaquinha and C. tricolor .

M̧ller Argoviensis (1865, 1873) misinterpreted C. micans Swartz (1800: 1185) , and described some species and the varieties using that name that are actually all C. argyrophyllus . That error resulted in large numbers of specimens of C. argyrophyllus in herbarium are still identified as C. micans . Van Ee & Berry (2009), however, demonstrate the true identity of C. micans and discussed the history of this species, which differed from that interpreted by M̧ller Argoviensis.

Gomes (2006) admitted C. nervosus as a species distinct from C. argyrophyllus based on the shape and indumentum of the nectary disk of the staminate flower and the type of trichome on the adaxial surface of the leaf blade. Gomes et al. (2010) subsequently proposed C. schomburgkianus as a new name for C. nervosus , and continued to recognize it as different from C. argyrophyllus . Van Ee (2011) recognized those species as synonyms. We agree with van Ee (2011) that the characters used by Gomes (2006) to distinguish C. argyrophyllus from C. schomburgkianus are insufficient to differentiate two species. A more integrative approach may even reveal them as distinct, but we recognize C. argyrophyllus here as a polymorphic, widely distributed species that has subtle and continuous variations along its distribution.

Representative specimens: — BRAZIL. Acre: Rio Branco , Faz. S „ o Bento , 3 September 1951, Black 51 ( IAN) . Alagoas: Mata Grande, Serra da Boa Vista , 09º04’80” S, 37º71’80” W, 2 June 2001, R . P . Lyra-Lemos 5670 ( HST, HUEFS) . Bahia: Morro do Chapéu, Serra da Babilônia , 11º05’43” S, 41º16’19” W, without date, E . Antunes 614 ( HUEFS). Maranh „o: S „o Mateus do Maranh„o, Fazenda do Senhor Miguel Pacheco, Km 137 of BR-132, 04º00’ S, 44º50’ W, 27 September 1980, D. C . Dally 318 ( INPA) . Paraíba: Monteiro, propriedade de Zé do Boá, Faz. Olho D’água dos Silva , 07º87’67” S, 37º22’84” W, 13 May 2005, J . G . Carvalho-Sobrinho 2196 ( HVASF) . Pernambuco: Buíque, Faz. Laranjeiras , 8º62’50” S, 37º15’41” W, 22 February 1996, K . Andrade et al. 308 ( PEUFR) . Rio Grande do Norte: Martins, Sítio do Sr. Clesinho, entrada na saída para Umarizal , ca. 2 Km da entrada, 29 April 2012, J . G . Jardim et al. 6208 ( JPB) . Rondônia: Rio Crespo, Faz. De Santa Adelaide , 07 December 1981, J . G . Kuhlmann 6618 ( CEPEC) . Roraima: Boa Vista, estrada BR-174 na beira do rio Caomé , 02º83’33” S, 60º66’66” W, 5 August 1986, J . A . C. Silva 623 ( INPA) . Sergipe: Canindé de S „o Francisco, Faz. Jerimum, Mata ciliar do baixo curso do Rio S „o Francisco , 09º37’87” S, 37º43’53” W, 29 March 2005, D. Coelho 661 ( UFP) .

Figures

FIGURE 4. a–e Croton argyrophyllus: a fruiting branch with sympodial ramification b lanceolate stipules, c staminate flower with up to 18 stamens, d pistillate flower with horizontally (and slightly vertically) reduplicated sepals, long ovoid ovary and multifid style, e ovoid fruit showing horizontally and vertically reduplicated sepals. f–j C. blanchetianus: f flowering branch with monopodial ramification, g lanceolate to auriculate stipules, h staminate flower of ca. 16 stamens, i pistillate flower with vertically reduplicated sepals, glabrescent internally, and spheroid to obloid ovary with multifid styles forming a column, j spheroid fruit, showing vertically and horizontally reduplicated sepals. k–o C. claussenianus: k flowering branch with monopodial ramification, l 3-lobed stipule, m staminate flower of 5 stamens, n pistillate flower with horizontally reduplicated sepals, filiform glands (reduced petals), spheroid ovary and 2-partite styles, o spheroid fruit.

FIGURE 6. Distribution of some species of section Lasiogyne. a Croton argyrophyllus, C. blanchetianus, and C. claussenianus; b C. compressus, C. floribundus, and C. jacobinensis.