Euphorbia longipedunculata O.L.M.Silva & Riina

Silva, Otávio Luis Marques da, Braun, Pierre, Riina, Ricarda & Cordeiro, Inês, 2021, Three new species of Euphorbia subgenus Chamaesyce (Euphorbiaceae) endemic to Brazil, European Journal of Taxonomy 733, pp. 72-86 : 77-78

Euphorbia longipedunculata O.L.M.Silva & Riina sp. nov.

http://www.ipni.org/urn:lsid:ipni.org:names:77214814-1

Figs 2–3

Diagnosis

Euphorbia longipenduculata O.L.M.Silva & Riina sp. nov. is most closely related to Euphorbia potentilloides Boiss. , but differs in its orbicular leaves, long-pedunculate cyathia (5–10 mm long, reaching up to 45 mm long when the cyathium is fully developed) and longer cyathial gland appendages (ca 3 × 4 mm).

Type

BRAZIL • Goiás, Cavalcante, Estrada Minaçu – Cavalcante , “passando pela balsa Serra Branca, a cerca de 126 km do rio Tocantins” [after Serra Branca ferry, around 120 km from Tocantins river]; 13°35′35″ S, 47°31′24″ W; 1120 m a.s.l.; 10 Nov. 2000; B.M.T. Walter et al. 4688; holotype: SP[360090] ; isotypes: CEN[CEN00041136] , HUEFS[HUEFS000199840] , SP[468419] .

Etymology

The epithet is a reference to the long peduncle of the cyathium ( Fig. 3A ), which is remarkable among all species of Euphorbia in Brazil.

Description

Erect monoecious herbs, up to 20 cm tall; underground system probably xylopodiferous, unbranched; latex white. Stems terete, dichotomously branched from the base, slightly reddish when dried, glabrous. Leaves opposite, persistent, subsessile (petioles reaching up to 1.5 mm long); stipules interpetiolar, deltoid, inconspicuous (up to 1 mm long), apex with stiff short (up to 0.25 mm long) simple trichomes; leaf blade membranaceous, glabrous on both surfaces, discolorous (abaxial surface glaucous), orbicular, (0.8–)1–1.5(–1.7) × (0.8–)1–1.5(–1.7) cm, base obtuse to slightly truncate, margin entire, thickened, apex cuspidate, venation brochidodromous. Cyathia solitary at the axils of dichotomous branches, longpedunculate; peduncle 5–10 mm long (reaching up to 45 mm long when cyathium is fully developed), glabrous; cyathophylls similar to the leaves; involucre campanulate, 3–5 × 3–5 mm, actinomorphic, glabrous on the outer surface; involucral lobes triangular, pale when dried, apex partite, glabrous; cyathial glands 4 or 5, yellowish when dried, transversely elliptic, slightly concave, glabrous on both surfaces, 0.2–0.3 × 0.5–1 mm; cyathial gland appendages petaloid, wide-obovate, ca 3 × 4 mm, white when dried, glabrous on both surfaces, margin crenate, veins conspicuous. Staminate flowers 25(30), arranged in 5 cincinni with 5(6) flowers each; bracteoles lanceolate, ciliate; pedicels up to 2 mm long, filaments up to 1 mm long, anthers ca 1 mm wide, dorsifixed, extrorse, transversely dehiscent. Pistillate flowers ca 3.5 mm long; pedicel up to 2 mm long; ovary globose, ca 1 × 1 mm, glabrous; styles 3, up to 0.5–0.8 mm long when fully developed, united only at the base, shortly bifid at the apex. Capsule 3-lobed, subglobose, 3–4.5 × 4–5 mm, glabrous, pale when dried; pedicel shortly accrescent, reaching up to 5 mm long; columella ca 3 mm long; seeds brown, ovoid, 1.8–2.3 × 1–1.2 mm, rounded in cross section, testa slightly tuberculate; caruncle absent.

Distribution, ecology, and phenology

Euphorbia longipedunculata sp. nov. grows in open cerrado vegetation (ʻcampo limpoʼ) near the Chapada dos Veadeiros in northern Goiás, within the Cerrado domain ( Fig. 2 ).

Provisional conservation status

Euphorbia longipedunculata sp. nov. is only known from a single location ( Fig. 2 ), it has AOO <10 km ² and EOO <100 km ². As this location is close to roadsides, it is subject to continuing decline in area, extent and quality due to the always growing anthropic pressure in Central Brazil. In the light of this, we suggest that this new species be classified as Critically Endangered (CR; B2ab[iii]).

Figures

Fig. 2. Geographical distribution ofEuphorbia blepharadena O.L.M.Silva & Cordeiro sp. nov. (triangle), E. longipedunculata O.L.M.Silva & Riina sp. nov. (star) and E. sobolifera O.L.M.Silva & P.J.Braun sp. nov. (square).

Fig. 3. Euphorbia longipedunculata O.L.M.Silva & Riina sp. nov. A. Habit. B. Cyathium, C. Opened cyathium, showing staminate cymules and bracteoles, D. Young fruit. E. Seeds in ventral (left) and dorsal (right) views. Illustrations of the holotype, B.M.T. Walter et al. 4688 (SP), by Klei Souza.