Coccoloba tunii Ortiz-Díaz & Arnelas, 2016

Ortiz-Díaz, Juan Javier, Arnelas, Itziar & Pinzón, Juan P., 2016, Coccoloba tunii (Polygonaceae), a new species from Chiapas (Mexico), Phytotaxa 275 (1), pp. 75-80 : 76-78

Coccoloba tunii Ortiz-Díaz & Arnelas , sp.nov. ( Fig. 1 )

Type: — MEXICO. Chiapas: Chiapa de Corzo, El Chorreadero en las laderas de la cascada. Selva baja caducifolia con Hauya , Euphorbia , Diospyros , Cedrela , Trichilia y Heliocarpus , 800 m a.s.l., 14 September 2014, Ortiz & Palma 2942 (Holotype UADY!, isotypes MEXU!, MO!, XAL!).

Diagnosis: —Similar to Coccoloba liebmannii , differing in elliptic to elliptic oblong or narrowly ovate, chartaceous leaf blades, shorter racemes, longer pedicels and perianth lobes.

Description: — Trees 3–7 m tall; stem smooth with irregular cork pieces, internodes 0.7–3.4 cm long (diameter 3– 5 mm), striate, sparsely lenticelled, sparse to densely pubescent, trichomes simple, 0.2–0.3 mm long, green-yellowish; ochreae 3–7 mm long, cylindrical, lacerate at apex, chartaceous, sparse to densely pubescent, trichomes simple, 0.2–0.3 mm long, green-yellowish, sparsely glandular punctiform, dark brown. Leaves simple, alternate; petioles 5–7(–11) mm long (diameter 0.5–1.0 mm), densely pubescent, trichomes simple, 0.2–0.3 mm long, green-yellowish, canaliculated, arising near or at the base of the ochreae; leaf blades (3.5–)6.7–10.3(–11.2) × (2.2–)2.4–3.2(–4.6) cm, elliptic to elliptic oblong or narrowly ovate, chartaceous, scarce to sparsely pubescent above and beneath, trichomes simple, 0.2–0.3 mm long, green-yellowish, base rounded to subcordate, apex obtuse to shortly acuminate, margin entire to slightly undulate; nerve prominent above, 5–8 pairs of primary nerves. Inflorescences terminal, solitary, racemes (2.7–)4.5–5.1(–6.2) cm long, rachis rounded (0.5–) 1–2 mm wide, sparse to densely pubescent, trichomes simple, 0.2–0.3 mm long, green-yellowish; ochreolae 0.3–0.7 mm long, sparsely pubescent, trichomes simple, 0.2–0.3 mm long, green yellowish, with a fringe of trichomes at apex; pedicels 3–6(–8) mm long, glabrous, longer than ochreolae, articuled at apex; flowers solitaries, 2.5–3.0 mm long, glabrous; hypanthium 1–1.3 mm long, 5 perianth lobes 1.5–1.8 mm long, glabrous, creamy to yellowish. Stamens 9–10, connate at base, glabrous, filaments 1.5–1.7 mm long, filiform; anthers 0.3–0.5 mm long, dorsifixed, yellowish. Ovary 1.0– 1.4 mm long, glabrous, style 3; stigma 3, linear. Fruit 6–7(–10) mm long × 5.9–7.0(–9.7) mm diameter, globose with a rounded to obtuse base, glabrous to powdery, glandular puntiform, green to dark brown when mature; achene included among the accrescent and succulent hypanthium and perianth lobes; perianth lobes free up to medial part of the fruit. Seed with ruminate endosperm; embryo straight.

Eponymy: — The epiteth is dedicated to Juan Tun Garrido, curator of UADY herbarium who has contributed to a better knowledge of the tropical flora of South Eastern Mexico.

Distribution and ecology:— Coccoloba tunii is a tree growing in cliff faces or disturbed slopes on limestone or sandstone, along banks rivers in tropical dry forests at an elevation of 650–1800 m ( Fig. 2 ). It is only known from the physiographic regions Central Depression, and Chiapas Plateau ( Müllerried 1957).

Conservation status:— Coccoloba tunii mostly occur in the Central areas of Chiapas, in the Biosphere Reserve “Selva del Ocote” (IUCN & UNEP, category VI, WDPA 2014) ( Fig. 2 ). On the basis of the available data (IUCN 2012) we can use the criterion B1. The area of occupancy (AOO) of the new species is less than 2000 km 2, suggesting the inclusion of it in “vulnerable” (VU) IUCN criteria. However, considering the number of available herbarium material studied, we assumed the presence of more than six populations over the distributional range of the new species ( Fig. 2 ). Therefore, we considered that C. tunii is in a “least concern” (LC) category.

Observations:—On the basis of the morphological characters, Coccoloba tunii appears to be similar to C. liebmannii ( Table 1). C. tunii differs from C. liebmannii in having elliptic to elliptic oblong or narrowly ovate (vs. oblong to obovate in C. liebmannii ), chartaceous leaf blades (vs. coriaceous), shorter racemes, longer pedicels and longer perianth lobes ( Table 1). The two species also have different distributional areas ( Fig. 2 ): Coccoloba liebmannii ranges from Colima to Oaxaca as a part of the Floristic Province Pacific Lowlands at elevational range of 0 to 550 m. Only one collection is known from Chiapas (Itié 3878, MEXU). Like C. liebmannii , C. tunii inhabits tropical dry forests but the latter is endemic to Central Depression, and Chiapas Plateau provinces at an elevation range of 650 to 1800 m.

Additional specimens examined (paratypes): — MEXICO. Chiapas. Municipio Berriozabal: 5 km E of Berriozabal along Mexican hwy 190, 11 October 1971, Breedlove 20383 ( CAS, MO). Municipio Chiapa de Corzo : Above El Chorreadero , 11August 1972, Breedlove 26875 ( CAS, MO) ; El Chorreadero, 5.6 miles SE of Chiapa de Corzo along Mexican hwy 190, 20 September 1967, Shilom Ton 2968 ( MO). Municipio Chicoasén: Mirador of Chicoasen Dam along road from Tuxtla GTZ to the Chicoasen Dam, 9 September 1976, Breedlove 39949 ( MO) ; 2 km al NO de la estación meteorológica CFE, Chicoasén, 5 May 2009, Martínez 2617 ( MEXU). Municipio Comitán de Domínguez: 5 km al N de J. Mújica, camino a Tzimol, 15 December 1987, Martínez & García 22097 ( MEXU). Municipio La Trinitaria : 18 km S of La Trinitaria , 29 October 1980, Breedlove & Strother 46993 ( MO). Municipio Ocozocuautla : Mirador Manos que Imploran, 42 km al N de Tuxtla Gutiérrez en el camino a Chicoasén, 17 June 1991, Hernández et al. 2559 ( MEXU) ; En bajada del Rio Encajonado La Venta, 3 km de la caseta Reserva el Ocote , 20 August 1990, Méndez 9487 ( CHIP) ; Along river 13 km E of Ocozocuautla on rte 190, then N road to Aguacero , 2 October 1984, Huft et al. 2297 ( MO) ; At the head of the Rio de La Venta at The Chorreadero near Derna , 24 August 1972, Breedlove 27387 ( MO) ; Al Rio La Venta, 30 km al NO de Ocozocuautla, 28 March or May 1950, Miranda 6310 ( MEXU). Municipio San Fernando: Al E de cañada La Chacona, 22 October 1988, Palacios & Breedlove 744 ( CHIP, MO) ; Arriba en cañada Chacona-San Fernando NO de Tuxtla Gtz. , 8 January 1970, Miranda 5876 ( MEXU) ; Arriba Encañada carretera a San Fernando , 18 June 1950, Miranda 6404 ( CHIP, MEXU) ; Cañada la Chacona , lado E, 10 August 1989, Palacios 1253 ( CHIP) ; At Mirador for Chicoasen Dam along road from Tuxtla Gtz to the Chicoasen Dam , 16 July 1981, Breedlove 51583 ( MO). Municipio Tzimol: 15 km S of Comitán on road to Tzimol and Tuxtla Gtz., 20 October 1981, Breedlove 53733 ( LL, MO) .

Figures

FIGURE 1. Coccolba tunii. Drawing based on the holotype. A) Branch, leaves and inflorescence axis. B) Detail of indumentum on midvein, and primary veins. C). Portion of the inflorescence, bracteoles, ochreolae and pedicel D) Ochrea and petiole. E) Fruit.

FIGURE 2. Distribution map of Coccoloba tunii (circle) and C. liebmannii (triangle).