Euphorbia berryi V.W. Steinm., 2022

Steinmann, Victor W., 2022, Euphorbia berryi: a narrowly endemic Brazilian species, Phytotaxa 545 (2), pp. 217-223 : 218-222

Euphorbia berryi V.W. Steinm. , sp. nov.

Type:— BRAZIL. Maranhão: município de Carolina, Estrada da cahoeira do Garrote , cerca de 3 km do asfalto, margem direita do rio Pedra Caída , 7º01’24”S, 47º28’21”W, 187 m, 25 February 2005, G. Pereira-Silva 9661 (holotype SP-468423 image! ; isotype CEN-00066779 image!). Figs. 1 , 2 .

Similar to other members of Euphorbia sect. Anisophyllum in having dichotomous branching, opposite leaves, interpetiolar stipules, and ecarunculate seeds. It differs by the combination of being a delicate annual with the stipules united into an erose sheath; slender styles that are notched at the apex; and linear, entire, strongly falcate leaves that are scarcely asymmetrical at the base and have a white, straight to flexuous, quickly deciduous, hairlike extension at the apex. The latter feature is apparently unique in the section.

Erect delicate annual 9–20 cm tall, dichotomously branched, from a slender taproot; stems glabrous, terete, internodes of main stems 1.1–3.2 cm long; cotyledons with a petiole 1.5 mm long, oblong, 2.7 mm long, 1.7 mm wide; stem leaves opposite, stipules interpetiolar, united into an ovate to deltoid sheath, 0.3–0.4 long, 0.4–0.5 mm wide at the base, erosely margined, glabrous; petiole 0.2–0.5 mm long, glabrous, blade linear, strongly falcate, 3–19 × 0.9–1.3 mm, entire, only the midvein evident, base acute to narrowly cuneate, not noticeably asymmetrical, apex when young with a white, straight to flexuous hairlike extension 0.5–0.7 mm long, this quickly deciduous leaving an acute tip, both surfaces glabrous; cyathia solitary, peduncle 0.2–0.3 mm long; involucre campanulate, 0.6–0.7 × 0.7–0.8 mm, glabrous on the outside, densely pilose within towards the opening, lobes ovate to oblong, 0.2 mm long, ciliate; glands 4, transversely oblong, equal in size, 0.2 × 0.3–0.5 mm, glabrous, slightly concave, appearing yellowish when dried; appendages present, transversely oblong to transversely reniform or flabellate, equal in size, 0.3–0.4 × 0.6–0.7 mm, hyaline, pinkish in age, entire, glabrous; staminate flowers ca. 10, bracteoles few, pilose; ovary 3-lobed, glabrous, styles 3, free, slender, 0.3–0.4 mm long, notched at the apex; gynophore exserted 0.4–1.2 mm, capsule oblate-ovoid, 3-lobed, 1.8–2.0 × 2.1–2.4 mm, glabrous, columella 1.4–1.5 mm long; seeds ovoid, 1.3–1.5 × 0.7–0.8 mm, 4-angled in cross-section, the dorsal facets convex, longer than the ventral facets, dorsal keel prominent but low and rounded, base truncate, apex a blunt point, smooth to inconspicuously roughened, reddish brown, ecarunculate.

Distribution, habitat, phenology, and conservation status:— Euphorbia berryi is endemic to Brazil and known only from the municipality of Carolina in the northern state of Maranhão at elevations from 187 to 375 m ( Fig. 3 ). Although the label of the type collections states “06ºS”, this is an error, and the locality described is actually at 07ºS. The distance between the two farthest known localities is 17 km (airline), and vegetation is described as seasonally dry “ Cerrado ”, a tropical savanna-like community that is extensive in central Brazil. It inhabits sandy soils that are periodically grazed and burned. Flowering and fruiting occur from January to May.

The new species is known from five collections all taken from a small area along or near the highway from Carolina to Estreito. The extent of occurrence (EOO) is calculated to be 23.825 km 2, and the area of occupancy (AOO) is 20 km 2. There is no detailed information about population size or potential reductions, although one specimen states that the plants were frequent and another that the plants were occasional. The remaining specimens do not provide data about abundance. The Cerrado ecoregion is considered highly threatened by agricultural practices such as cattle grazing and conversion to farmland. However, Euphorbia berryi may benefit from its diminutive stature and occurrence on sandy substrates. If plausible treats do exist, its reduced distribution would warrant assessment as Endangered under criteria B1 and B2 (following IUCN 2022). However, at present it should be treated as Data Deficient (DD) until the populations can be evaluated in the field.

Etymology:—This species is named in honor of Dr. Paul E. Berry and in recognition of his numerous contributions to botany, in particular research on the Venezuelan flora and the genera Fuchsia Linnaeus (1753: 1191) , Croton Linnaeus (1753: 1004) , and Euphorbia . Regarding the latter, he was the team leader of the Euphorbia Planetary Biodiversity Inventory project (www.euphorbiaceae.org), a global endeavor that greatly advanced our knowledge of the taxonomy, evolution, and phylogenetics of the genus.

Taxonomic discussion:—The precise affinities of Euphorbia berryi are not clear. It undoubtedly belongs to Euphorbia subg. Chamaesyce sect. Anisophyllum , as defined by Yang et al. (2012), and possesses the distinguishing morphological features of the taxon: dichotomous branching, opposite leaves, interpetiolar stipules, and ecarunculate seeds. Other traits that support its placement in sect. Anisophyllum are the cyathia with four glands and petaloid involucral appendages; although these are not present in all species of sect. Anisophyllum , the vast majority have them. With nearly 400 species, this taxon is the most-diverse section of the genus. Likewise, it is the most-diverse section within Brazil, where 27 species previously have been documented ( Silva et al. 2020).

Euphorbia berryi is distinctive and cannot be confused with any other species of the genus. A few of its traits are uncommon for members of sect. Anisophyllum : linear strongly falcate leaves that are scarcely asymmetrical at the base and styles that are merely notched. Most species have strongly asymmetrical, non- or slightly falcate leaves and deeply divided styles. However, the most unusual feature is the leaf apex which when young bears a white, straight to flexuous hairlike extension that readily breaks off leaving an acute tip. Although some species of subgenus Chamaesyce possess similar leaf apices, e.g., Euphorbia adiantoides Lamarck (1788: 426) and relatives, these belong to sect. Alectoroctonum ( Schlechtendal 1847 [1846]: 252) Baillon (1858: 284).

In the current key to Brazilian species of Euphorbia included in the Flora do Brasil, Euphorbia berryi keys out to E. burchellii Müller Argoviensis (1874: 680) , to which the type collection was tentatively determined (as cf. Euphorbia burchellii by W. John Haydon in 1997). However, the two taxa are not particularly similar and show no indications of being closely related. Following the circumscription of Silva et al. (2021), Euphorbia burchellii is a perennial herb from thickened underground stems (vs. annual from a slender taproot) with involucres 2.5–3.5 × 2−4 mm (vs. 0.6–0.7 × 0.7–0.8 mm), 4–6(–7) involucral glands (vs. strictly 4), and seeds 2−2.3 × 1.2−1.8 mm (vs. 1.3–1.5 × 0.7–0.8 mm). Also, E. burchellii is not known from Maranhão but occurs nearly 500 km to the south in the states of Tocantins and Goiás.

Some specimens of Euphorbia berryi were also determined as Euphorbia potentilloides Boissier (1860: 3) , a widespread species known from Maranhão, including the municipality of Carolina. The latter has entire leaves that are sometimes linear and symmetrical at the base, thus superficially resembling those of Euphorbia berryi . However, there are clear differences between these species. Euphorbia potentilloides is a perennial herb from a thickened rootstock (vs. annual from a slender taproot) with non-falcate leaves that lack a hairlike extension at the apex (vs. falcate and bearing a hairlike extension). Also, Euphorbia potentilloides often has some verticillate leaves (vs. strictly opposite) and a pleiochasial arrangement of the cyathia (vs. solitary).

Additional specimens examined (paratypes):— BRAZIL. Maranhão: município de Carolina, Parque Nacional da Chapada das Mesas, ponto mais próximo da BR010, entre Carolina e Estreito , ca. 29 km de Carolina, 07º07’08”S, 47º25’24”W, 17 May 2011, I. Cordeiro 3271, N. Figueiredo & M.B.R. Carruzo (SP); município de Carolina, 20 km da cidada na estrada para Estreito , portal da Chapada, 7º11’13”S, 47º25’23”W, 296–350 m, 21 January 2021, R.M. Harley 56590 et al. (HUEFS); município de Carolina, Rodovia BR-010, Carolina-Estreito, km 26, entrada para a cachoeira do Dodô, 7º6’10”S, 47º25’50”W, 280 m, G. Pereira-Silva 13271 (CEN); município de Carolina, Transamazonian Highway, BR 230 and BR010, Pedra Caida, 35 km N of Carolina, “ponto turistico” west towards Serra Baleia, 07°08’S, 47°25’W, [± 375 m], 14 April 1983, E.L. Taylor et al. E1207 (F, K, MO, NY, US) .

Figures

FIGURE 1. Specimen of Euphorbia berryi at NY. Image courtesy of the C.V. Starr Virtual Herbarium.

FIGURE 2. Euphorbia berryi. A. Branchlets. B. Flowering branchlet. C. Leaf apex. D. Seeds. E. Cyathium and leaves. F. Cyathium. G. Stipules.All photos from E.L. Taylor et al. E1207 (F).

FIGURE 3. Map indicating the known distribution of Euphorbia berryi.