Coccoloba rzedowskii 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 : 143-145

15. Coccoloba rzedowskii J.J.Ancona , sp. nov. ( Fig. 18A–G ).

Type: MEXICO. Colima: Coquimatlán, 5.2 km en línea recta al S de Zinacamitlán, camino a las Conchas, 18°56’10” N, 103°41’11” W, 240 m, 16 August 2022, Ibarra et al. 5985 (holotype MEXU!, isotype IEB!).

Diagnosis:— Coccoloba rzedowskii is similar to C. hirsuta , differentiated by the ochrea 5–8 mm long, scabrid to puberulent (vs 10–12 mm long, densely hirtellous); blades 7–15 × 5–12.5 cm, ovate to widely ovate, adaxially glabrous, sparsely hirsute or hispid mainly on veins, abaxial surface densely hirsute, hispid or pilose (vs 15–25.5 (–28.3) × 9–13 cm, oblong–elliptical to obovate–elliptic, adaxial surface sparsely puberulent to hirtellous mainly on veins, abaxial surface densely hirtellous); inflorescence racemiform, pedicels in flower 1–1.5 mm long, pedicels in fruit 1.5–2.3 mm (vs inflorescence spiciform, pedicels in flower 0.5–1 mm long, pedicels in fruit 0.5–1.5 mm).

Description:— Trees hermaphrodites, functionally unisexual, 4–12 m tall; branch striate, glabrous, brown to greyish, sparsely punctiform, sparsely lenticelated; ochrea 5–8 mm long, cylindrical, scabrid to puberulent, margin lacerated. Leaves simple, alternate; petioles 1.5–3 cm long, 0.8–2 mm diameter, striate, puberulent to puberulous, brown, arising at the base of the ochrea; leaf blades 7–15 cm long, 5–12.5 cm wide, ovate to widely ovate, chartaceous to coriaceous, adaxially glabrous, with sparsely hirsute or hispid trichomes on primary and secondary veins, abaxial surface densely hirsute, hispid or pilose; margin entire to slightly undulate, apex acute or obtuse, base cordate, subcordate or rounded; venation brochidodromous, reticulate, abaxially prominent, primary veins 8–12 pairs. Inflorescence racemiform, arranged in a small sympodial panicle, 3–4 branches, main axis reduced, 1–1.5 cm long, striate, puberulent to pulverulent; racemiform portion 9–15 cm long, rachis 1–1.7 mm diameter, striate, puberulent to puberulous; bracteole 1 mm long, cymbiform, puberulent to puberulous; ochreola 1 mm long, tubular, lacerate, membranous, glabrous to puberulent; pedicels in flower 1–1.5 mm long, pedicels in fruit 1.5–2.3 mm, thicker, glabrous, pulverulent. Flowers aestivation quincuncial, two whorls, outer tepals 3, inner tepals 2, alternate, outer tepals coriaceous, inner tepals papyraceous; flowers functionally male 2–3 × fascicle, 2.2–2.5 mm long; hypanthium 0.7–1 mm long, glabrous, campanulate; tepals 1.2–1.5 mm long, glabrous; stamens 8, 1.5–2 mm long, filaments filiform 1–1.5 mm long, anthers 0.3–0.5 mm long; ovary 0.8 mm long, trigonous, glabrous, style 3, 0.5 mm long; flowers functionally female solitary, 2.2–2.5 mm long; hypanthium 1.7–2 mm long, glabrous, campanulate; tepals 1.2–1.5 mm long, hirtellous to pulverulent; stamens 8, 1 mm long, filaments filiform 0.5–0.8 mm long, anthers 0.5 mm long; ovary 1.5–2 mm long, trigonous, glabrous, style 3, 0.8–1 mm long. Fruit acrosarcum, 7–10 mm long, 6.5–8 mm diameter, ovoid-subglobose, glabrous, apex rounded to obtuse, base rounded, abruptly contracted at junction with pedicel; hypanthium accrescent, succulent, almost completely enclosing achene, tepals accrescent, subcoriaceous, appressed at the apex of the achene. Achene 6–8 mm long, 5–7 mm diameter, subglobose to globose, base rounded, apex slightly cuspidate, mammiform, slightly prominent, brown, smooth, glossy.

Etymology:—The specific epithet of this new species is in honor to Dr. Jerzy Rzedowski Rotter (1926 – 2023) for his long career in the study of Mexican flora.

Phenology:—Flowers from May to July; and fruits from August to November.

Distribution and ecology:—This species is endemic to Mexico, inhabits the low deciduous forests of Colima, Jalisco and Michoacán ( Fig. 18H ), at elevations of 50– 500 m.

Provisional conservation status:—The EOO is 7,375 km 2, within the threshold for Vulnerable (V) status under subcriterion B1, and the AOO is estimated as 36 km 2, which is below the threshold for Endangered (EN) status under subcriterion B2. There are 12 known occurrences of C. montana representing three to four subpopulations. Most occurrences are located outside protected natural areas, except for the occurrences in Jalisco, Mexico, which are located within the Chamela-Cuiuxmala reserve. Occurrences outside Chamela-Cuiuxmala are located in areas with vegetation fragmented by urban growth and agriculture. Under the IUCN Red List criteria ( IUCN Standards and Petitions Committee 2024), we propose a preliminary IUCN Red List Assessment of Endangered [EN B1ab(iii)+2ab(iii)].

Specimens examined: — MEXICO. Colima: Colima, km 17 de la Autopista Colima-Manzanillo, laderas calizas, 19°05’12” N, 103°46’27” W, 500 m, 19 March 2002, Carrillo-Reyes & Ramírez-Delgadillo 3044 (IEB, MEXU). Michoacán: Aquila, 7 km al S de la Placita, 290 m, 20 October 1985, Soto-Núñez et al. 11209 (MEXU); Aquila, a 18 km al W de Arenas Blancas, carr. Tecomán-Col. Playa Azul, 26 September 1983, Martínez 4570 (MEXU); Aquila, 2.24 km SO de Cruz de Campos , carretera Aquila-El Ticuiz, 18°34’14” N, 103°36’13” W, 64 m, 28 May 2009, Medina- Lemos 4676 (MEXU); Aquila, a 9 km al E de La Placita, carr. Tecomán, col. Playa Azul, 18°27’59” N, 103°33’22” W, 175 m, Martínez et al. 4518 (MEXU); Caleta de Campos , 10 km al NW de Caleta de Campos , 18°07’00” N, 102°52’00” W, 90 m, 10 October 1990, Trejo 1752 (MEXU). Jalisco: La Huerta, Estación de Biología Chamela, cuenca 3a 1250, 19°30’00” N, 105°03’00” W, 27 November 1998, Pérez 2357 (MEXU); La Huerta, antiguo camino a Nacastillo, en la parte alta de la estación, a 9.1 km al E de la carr. Puerto Vallarta-Barra de Navidad, 190 m, 7 July 1985, Lott & Ayala 30 (IEB, MEXU); La Huerta, a 10 km al NO de las oficinas de la Fundación Ecológica Cuixmala, sobre el camino al Mirador, 19°28’26” N, 104°58’29” W, 300 m, 13 September 1997, Calónico-Soto et al. 4282 (IEB, MEXU).

Figures

FIGURE 18. A. Specimen of Coccoloba rzedowskii (G. Ibarra-Manríquez et al. 5985, MEXU); B. Ochrea; C. Portion of inflorescence and pedicels; D. Acrosarcum lateral view; E. Acrosarcum polar view; F. Achene lateral view; G. Achene polar view; H. Geographical distribution.