Coccoloba steinmannii J.J.Ancona, 2025

Ancona, Juan José, Ortiz-Díaz, Juan Javier, Gutiérrez-Alonso, Eduardo & Ledesma, Patricia Hernández, 2025, A taxonomic revision of Coccoloba sect. Paniculatae (Polygonaceae, Eriogonoideae), Phytotaxa 704 (2), pp. 106-152 : 145-147

16. Coccoloba steinmannii J.J.Ancona sp. nov. ( Figs. 19A–F ).

Type: MEXICO. Oaxaca: Pluma Hidalgo, departamento de Pochutla, Cerro Espino, al E de la Finca cafetalera “Monte Cristo”, 15°52ʹ00ʺN, 96°24ʹ00ʺW, 1250 m, 2 October 1988, Campos 2479 (holotype MEXU!).

Diagnosis:— Coccoloba steinmannii is similar to C. montana , it is differentiated by its elliptic, elliptic-ovate, oblanceolate blade, acute apex, symmetrical cordate base (vs. ovate blade, long-acuminate apex, cordate base, asymmetrical); acrosarcum smooth (vs acrosarcum with prominent ribs).

Description:— Trees hermaphrodites, functionally unisexual, 5‒20 (–30) m tall; branches glabrous, striate, lenticelated, brown or grayish; ochrea 5–10 mm, coriaceous, glabrous when mature, puberulent when young, edge obtuse-truncated, base persistent. Leaves simple, alternate; petiole 8–10 (25 when young) mm long, 1–3.5 mm diameter, glabrous, articulated at the base of the ochrea, leaf blade elliptic, elliptic-ovate, oblanceolate, 10–23 cm long, 4–14 cm wide, apex acute to acuminate, base subcordate to rounded, margin entire to wavy, chartaceous to coriaceous, glabrous on both surfaces, venation brochidodromous, reticulate, 6–10 pairs of lateral veins, abaxially conspicuous. Inflorescence racemiform arranged in a small sympodial panicle, 3–4 branches, main axis reduced, 1–1.5 cm long, 1.5–2.0 cm long, 1.5–2.3 mm diameter, ribbed, glabrous; racemiform portion 7–15 cm long, rachis ribbed, striate, glabrous or pulverulent, 1.3 mm diameter; bracteole 0.5 mm long, cymbiform, glabrous to pulverulent; ochreola 0.5– 0.8 mm long, tubular, lacerate, membranaceous, glabrous; pedicels in flower 1–1.2 mm long, pedicels in fruit 1.0– 1.5 mm long, thicker, glabrous. Flowers not observed, specimens only have flower buds. Fruit acrosarcum, 7.5–8.5 (–1.0) mm long, 6–7.5 mm diameter, globose-suglobose rarely ovoid, glabrous, apex acute to obtuse, base truncate or flat, rarely abruptly contracted at junction with pedicel; hypanthium accrescent, succulent, almost completely enclosing achene, tepals accrescent, glabrous, succulent, appressed at the apex tuberculate of the achene. Achene 6–6.5mm long, 7–8 mm diameter, ovoid-subglobose, base truncate or flat, apex tuberculate, mammiform, slightly prominent, brown, smooth, glossy.

Etymology:—The specific epithet of this new species is in honor of Dr. Victor Steinmann, a botanist specializing in taxonomy and systematics of the Euphorbiaceae family and in Mexican floristics.

Phenology:—Flower from December to July; and fruits from May to October.

Distribution and ecology:— Coccoloba steinmannii is endemic to Mexico, in the states of Guerrero and Oaxaca ( Fig. 19G ). This species inhabits very humid and rainy forests (medium sub-evergreen forest and tall evergreen forest) and cloud forests, at elevations of 600 to 1600 m.

Provisional conservation status:—The EOO is 11,553.26 km 2, within the threshold for Vulnerable (VU) status under subcriterion B1, and the AOO is estimated as 40 km 2, which is below the threshold for Endangered (EN) status under subcriterion B2. There are seven known occurrences of C. stenmannii representing two to three subpopulations. However, occurrences are located in conserved areas, but this does not indicate that in the future they will be severely fragmented. According to the IUCN methodology ( IUCN Standards and Petitions Committee 2024), if the EOO threshold is lower than the AOO threshold, the EOO should be set equal to the AOO to ensure consistency with the definition of AOO as an area within the EOO. Therefore, C. steinmannii is assigned a preliminary status of Endangered [EN B2ab(iii)].

Specimens examined:— MEXICO. Guerrero: Leonardo Bravo , 4 km antes de Yerbabuena, 3 km después de Cruz de Ocote, carr. Filo de C. a puerto Gallo, 19 July 1989, Contreras 1237 ( MEXU) ; Atoyac de Álvarez , 1 km al N de río Santiago, 800 m, 11 July 1985, Valverde 75 ( MEXU) ; Chilpancingo de los Bravos , 1 km al O de La haciendita, carr. Chilpancingo-Tierra Colorada, 610 m, 3 July 1981, A. Núñez 118 ( MEXU) . Oaxaca: Pluma hidalgo, departamento de Pochutla, camino Copalita-Pluma Hidalgo, 1000 m, 17 April 1989, Acosta-Castellanos 1219 ( MEXU) ; San Miguel del Puerto , distrito de Pochutla, 2 km de Rancho Dion rumbo a cerro Lobo, 20 July 2002, Saynes, et al. 2985a ( IEB, MEXU) .

Figures

FIGURE 19. A. Specimen of Coccoloba steinmannii (A. Campos 2479, MEXU); B. Portion of inflorescence and pedicels; C.Acrosarcum lateral view; D. Acrosarcum polar view; E. Achene lateral view; F.Achene polar view; G. Geographical distribution.