Garcinia isthmensis Mouzinho, 2025

Mouzinho, Thiago, Carrión, Juan F., Marinho, Lucas Cardoso & Giacomin, Leandro Lacerda, 2025, Garcinia isthmensis (Clusiaceae): a new tree species for Central America, Phytotaxa 708 (1), pp. 16-22 : 17-21

Garcinia isthmensis Mouzinho , sp. nov. ( Figs 1–2 ).

Type:— COSTA RICA. Puntarenas: Mun. Sierpe, Cantón Osa ; Reserva Forestal Golfo Dulce; Rincón, Cuenca de la Quebrada Aguabuena, fin del Camino, finca Montoya, 08°42’19’’N, 83°31’9’’W, elev.: 163 m, 01 January 2008, fl. ♂, R. Aguilar 10734 (holotype: NY barcode NY-1095906!; isotype: PMA barcode PMA-104857!) .

Diagnosis: — Garcinia isthmensis is vegetatively similar to G. magnifolia due to its elliptical to elliptic-oblong shape and size of the leaf blades (≥ 19 cm long), but differs from it due to its slightly verrucose branches (vs. smooth in G. magnifolia ), conspicuous exudate canals (vs. inconspicuous in G. magnifolia ), staminate flowers with 40–55 stamens per flower (vs. ca. 30 stamens in G. magnifolia ), non-rostrate fruits (vs. rostrate in G. magnifolia ) and fruit pedicels of 33.5–44 mm long (vs. 7–10 mm long in G. magnifolia ).

Description: —Trees with up to 15 m height and up to 30 cm DBH; stems with reticulated rhytidome, yellow exudate after cutting on the trunk; branches angular, striated with slightly verrucose texture in sicco, exudate yellow after cutting, orange when oxidized. Petioles 15.7–25.6 mm long; dilatation of the base of the petioles oblong in sicco. Leaf blades 19–36.2 × 6.2–11 cm, subcoriaceous, pale, greenish-brown and opaque on both surfaces in sicco, elliptic to elliptic-oblong, apex rounded to acute, base attenuated, margin revolute in sicco; secondary veins ≥ 20 pairs, reaching the margin of the blade, intersecondary veins parallel to the secondary veins with 2–3 pairs per intercostal area; intramarginal vein present, leaves with conspicuous in sicco; exudate canals conspicuous in sicco. Inflorescences axillary, the staminate fasciculate, with up to 10 flowers, with a mild aroma; bracteoles 2 per flower; pedicels 20–50 mm long, greenish, slightly verrucose. Staminate floral buds 4.5–6.1 × 5.8–6.6 mm, greenish, globose. Staminate flowers with 2 sepals, 5.5–6.8 × 5.5–5.7 mm, greenish, fleshy, rounded; petals 4, white, chartaceous, concave, the outer ones ca. 12 × 7.7 mm, rounded, the inner ones 11.5–12 × 5.4–6.5 mm, oblong; nectariferous disc ca. 6 mm diam., dark yellow, dome-shaped with a depression in the apex; stamens 40–55 per flower, arranged around the disc in 3 series, filaments 4.4–6 mm long, teretes, white to hyaline, anthers ellipsoid, orange, darkened when senescent, thecae 0.69– 0.72 × 0.42–0.45 mm. Pistillate inflorescence and flowers not seen. Fruits berries, smooth epicarp; sepals, staminodes and stigmas persistent; when ripe ca. 72.4 × 60 mm, orange, ovoid, rostrum absent; pedicels 33.5–44 mm long. Seeds 2–3, 39.3–44.4 × 20.6–22.6 mm, ellipsoid.

Additional specimens examined (Paratypes): — COSTA RICA. Limón: Cordillera de Talamanca, 10°01’N, 83°25’W, alt: 100-300 m, 20 October 1988, fl. ♂, G. Herrera & H. Martínez 2223 ( CR image!). Puntarenas: Reserva Forestal Golfo Dulce , Osa Península , rancho Quemado , 08°42’N, 83°33’W, Elev.: 250–350 m, 31 May 1988, fr., B. Hammel 1690 ( CR image!, MO image!). Dist. Golfito, Parque Nacional Piedras Blancas , 08°41’N, 83°15’W, Elev.: 250 m, 25 February 1999, fl. ♂, W. Huber & A. Weissenhofer 1495 ( CR image!, LI image!) ; ibid., Parque Nacional Esquinas, 08°39.868’N, 83°15.139’W, Elev.: 200 m, 16 August 2000, st., W. Huber & A. Weissenhofer 1977 ( LI image!) . PANAMA. Coclé: tramo en Potrero Llano, La Pintada y Llano Grande hasta Volteadero, 18 February 2000, bot., C. Guerra 1100 ( PMA!). Veraguas: Montijo, Isla Coiba, 07°38’N, 81°44’W, 23 February 1995, fr., C. Galdames et al. 2183 ( PMA!) .

Etymology: —The epithet refers to the Panama isthmus, that connects Meso- and South American regions.

Vernacular name: — Costa Rica: jorco, Panama: satra ( Hammel 2010).

Distribution, habitat and preliminary conservation status: — Garcinia isthmensis is restricted to southern Central America, in Costa Rica (Prov. Limón and Puntarenas) and Panama (Prov. Coclé and Veraguas), occurring in elevations between 200–350 m a.s.l. ( Fig. 3 ). The preliminary conservation status of G. isthmensis is assessed Vulnerable (VU), based on its extent of occurrence (EOO) of 22,964 km 2 and its area of occupancy (AOO) of 20 km ² [B1a + B2ai,ii] ( IUCN 2012). Garcinia isthmensis occurs in protected areas in Costa Rica, such as the humid forests of the Golfo Dulce Forest Reserve and the Piedra Blanca National Park, both locations that are part of the Osa Conservation Area (ACOSA). In Panama, G. isthmensis occurs in the humid forests of the Isla Coiba National Park.

Note: —In addition to its similarity with G. magnifolia (see diagnosis) ( Fig. 4 ), G. isthmensis can be confused with G. intermedia , the species with the largest extent of occurrence in Central America, but differs by striate branches with a slightly verrucose texture (vs. smooth in G. intermedia ), branches with orange exudate when oxidized (vs. yellowish-green in G. intermedia ), leaf blade with round to acute apex (vs. acuminate in G. intermedia ), staminate flowers with pedicels 20–50 mm long (vs. 8–10 mm in G. intermedia ) and staminate flowers with 40–55 stamens per flower (vs. ca. 20 in G. intermedia ).

Garcinia isthmensis has orange exudate on its branches when oxidized ( Fig. 2B ), unlike most Neotropical species for which yellowish-green exudate when oxidized is reported (see Mouzinho 2022). Observations related to the variation in exudate coloration in Garcinia have also been reported for G. leptophylla Bittrich (2018: 20 in Bittrich & Marinho 2018), which is an Amazonian species that has exudate on the branches with a reddish coloration when oxidized (Mouzinho et al. 2024). In this context, this study, together with that of Mouzinho et al. (2024), reinforces the importance of inform the part of the plant where the color of the exudate is observed, as demonstrated by Mouzinho & Ferreira-Silva (2024).

Figures

FIGURE 1. Holotype of Garcinia isthmensis Mouzinho at the NY herbarium (NY-1095906). Image courtesy of the C.V. Starr Virtual Herbarium (http://bluegum.nybg.org/science/vh/).

FIGURE 2. Garcinia isthmensis Mouzinho (R. Aguilar 10734). A. Branch. B. Cut branch, showing the exudate with orange-colored oxidation. C. Leaf blades. D. Staminate inflorescence. Photos: Reinaldo Aguilar. Image courtesy of the C.V. Starr Virtual Herbarium (http://bluegum.nybg.org/science/vh/).

FIGURE 3. Distribution of Garcinia isthmensis Mouzinho (red circles) and G. magnifolia (white triangles).

FIGURE 4. Type specimens. A. Garcinia intermedia (Pittier) Hammel in the US herbarium (US-01014026). B. Garcinia magnifolia (Pittier) Hammel in the US herbarium (US-01049910). Image courtesy of the Smithsonian National Museum of Natural History (https:// collections.nmnh.si.edu/).