Tabernaemontana chamelensis L.O. Alvarado & Lozada-Pérez, 2019

Alvarado-Cárdenas, Leonardo O., Lozada-Pérez, Lucio, Cadena, Joselin, Hernández, Sofia Islas-, Martínez-González, C. Ramiro, Cortez, Ericka B., González- Martínez, César A. & González-Ramírez, Ixchel S., 2019, The triad of knowledge: Systematic, diversity and conservation status of the Mexican species of Tabernaemontana (Apocynaceae; Rauvolfioideae: tribe Tabernaemontaneae), Phytotaxa 388 (1), pp. 1-46 : 19

4. Tabernaemontana chamelensis L.O. Alvarado & Lozada-Pérez sp. nov. ( Fig. 2 , 3 , 8 , 9 ).

Type:— MEXICO. Jalisco: Mun. La Huerta. Chamela, veg. selva baja caducifolia. 4 June 1982, J. A. S. Magallanes 3600 (holotype MEXU).

The new species is similar to Tabernaemontana amygdalifolia , but differs in the yellow corolla, absence of corolline corona, stamens inserted above the middle of the corolla tube and never exerted, and being restricted to the state of Jalisco, Mexico.

Treelets or shrubs 1–4 m tall. Petioles 0.38–1.8 cm long; blades 10–15 × 3–5 cm, membranaceous to firmly membranaceous, oblanceolate to elliptic, base acute, apex short-apiculate or acuminate, margin slightly undulate, glabrous on both sides. Inflorescence 4 flowers, peduncle 0.8–2.5 cm long; bracts 1.3–2.2 mm long, ovate, scarious; pedicels 0.9–1.3 cm long; sepals subequal, 2.5–3 mm long, ovate, obtuse to acute, inconspicuous venation; corolla hypocrateriform, yellow to whitish yellow with green, tube 1.5–1.8 × 0.2 cm, not twisted around the anthers, stamina ridges absent, suprastaminal corona absent, lobes 1.5–1.7 × 0.7–0.8 cm, obovate to elliptical; stamens inserted above the middle of the corolla tube, anthers 3–4 mm long, included, blue-green; pistil 1.1–1.3 cm long, nectary present. Follicles 2.9–3.9 × 1.6–1.9 cm, fusiform to ellipsoid, apiculate, with 2 lateral ridges, not lenticellate, glabrous; seeds 6–8 mm long.

Habitat and phenology: —Tropical subdeciduous and deciduous forest and secondary vegetation, with an altitudinal range of 0–310 m a.s.l. Flowering April to August and fruiting July to August.

Distribution: —Endemic to Mexico, restricted to the state of Jalisco ( Fig. 6a ).

Conservation status: —Endangered (EN). It is an endemic species with a restricted distribution, known only from a small area of Jalisco ( Fig. 6a ). Most of the specimens have been collected on the Chamela-Cuixmala Biosphere Reserve, and the others from a population in the municipality of Toliman. Its area comprises an EOO of 751 km 2 and AOO of 44 km 2, which is less than 0.1% of the national territory ( Table 3). Although the populations occur in protected areas, they are constantly under the impact of hurricanes on the Pacific coast. Based on the restricted area and the potential impact of climate, we suggest that T. chamelensis should be included in the category of endangered.

Additional specimens examined:— MEXICO. Jalisco: Mun. La Huerta Alrededor del km 9 del camino viejo de terracería a Nacastillo, que inicia en el km 63.5 de la carretera Barra de Navidad- Puerto Vallarta , 200 m a.s.l., 10 Sep 1997, Calónico 4133 ( HUMO) ; Antes de la entrada a la huerta de mangos, Arroyo Chamela, 01 Jul 1982, Lott 1131 ( MEXU) ; Arroyo Hornitos, exactamente en donde corre hacia el NE 5 km al E de la Estación de Biología Chamela UNAM, 90 m a.s.l., 11 Oct 1997, Calónico 4786 ( HUMO) ; Arroyo Maderas, antiguo camino a Nacastillo, 17.5 km al E de la carr Puerto-Vallarta. Barra de Navidad , 22 Aug 1985, Ayala 140 ( MEXU) ; Chamela, 23 May 1970, Pérez 44 ( MEXU) ; Chamela bay region ; Rancho Cuixmala, Río Cuixmala, ca. 0.5 mi downriver from headquarters, 11 May 1991, Lott 3430 ( MEXU) ; Chamela, Arroyo Chamela pasando la huerta de mango al E del puente, 5 m a.s.l., 05 Aug 1986, Lott 2830 ( MEXU) ; Ejido La Fortuna, km 75 de la carr Barra de Navidad-Puerto Vallarta, 16 Apr 1986, Ayala 718 ( MEXU) ; Estación de Biología Chamela, 15 Apr 1982, Lott 1005 ( MEXU) ; Estación de Biología Chamela, 29 May 1982, Lott 1079 ( MEXU) ; Estación de Biología Chamela, 8 May 1983, Bullock 1319 ( MEXU) ; Río Cuixmala, ca. One-half mile downriver from headquarters, 11 May 1991, Lott 3430 ( MEXU) ; Mun. Tomatlán Alrededores de estero El Ermitaño, 5 m a.s.l., 24 Sep 1994, Acevedo 1496 ( MEXU) .

Common names and uses: “cabrito”.

Notes: —The new species is similar in its vegetative and fruit morphology to T. amygdalifolia ( Fig. 2 , 3 , 8 , 9 ). Leeuwenberg labeled the specimens as an aberrant form of T. amygdalifolia with stamens included. After a detailed observation of the specimens that are restricted to the state of Jalisco, we concluded that they belong to another species, considering that T. chamelensis has yellow corolla (vs. white in T. amygdalifolia ), suprastaminal corona absent (vs. bilobed callus), and stamens inserted above the middle of the tube but never exserted (vs. inserted at the apex of the corolla tube and exserted). Attributes such as sepal lengths, corolla shape, presence of corolline appendages and position of the stamens have been important in differentiating species in Tabernaemontana ( Leeuwenberg 1994, Morales 2005).

Tabernemontana chamelensis could be closely related to the clade T. alba-T. amygdalifolia-T. citrifolia ( Simões et al. 2010) , because the stamens are inserted above the middle of the corolla tube and the anthers are a blue-green color. Inclusion of T. chamelensis in a phylogeny would provide evidence of its relationships and potential evolution of the suprastaminal corona in this group.

Figures

FIGURE 2. Comparison of flowers of selected species of Tabernaemontana in Mexico. a T. alba. b T. arborea. c T. stenoptera. d T. venusta. e T. chamelensis. f T. citrifolia. g T. amygdalifolia. h T. hannae. i T. oaxacana. j T. donnell–smithii. k T. ochoterenae. l T. eubracteata. m T. riverae. n T. glabra. o T. tomentosa. p T. litoralis.

FIGURE 3. Comparison of fruits of selected species of Tabernaemontana in Mexico. a T. alba. b T. amygdalifolia. c T. arborea. d T. chamelensis. e T. citrifolia (open fruit). f T. donnell–smithii. e T. glabra. h T. eubracteata. i T. hannae. j T. litoralis. k T. mixtecana. l T. oaxacana. m T. ochoterenae. n T. riverae (open fruits). o T. tomentosa.

FIGURE 6. Distribution maps of Tabernaemontana species in Mexico. a T. alba and T. chamelensis. b T. amygdalifolia and T. riverae. c T. arborea, T. eubracteata, and T. oaxacana. d T. citrifolia and T. hannae. e T. donnell–smithii and T. ochoterenae. f T. glabra and T. venusta. g T. litoralis and T. mixtecana. h T. stenoptera and T. tomentosa.

FIGURE 8. Holotype of Tabernaemontana chamelensis.

FIGURE 9. Comparison of flowers, fruits and corona lobes of Tabernaemontana chamelensis (a–b) and T. amygdalifolia (c–e). Abbreviation: St: stamens. CCo. Corolline corona.