Cestrum contrerasianum A.K.Monro, 2012

Monro, Alex K., 2012, Eight new species of Cestrum (Solanaceae) from Mesoamerica, PhytoKeys 8, pp. 49-82 : 54-56

Cestrum contrerasianum A.K.Monro sp. nov. Fig. 3 A-C

Diagnosis.

Most similar to Cestrum formosum C.V. Morton from which it can be distinguished by its more compact inflorescences, bearing flowers on shorter pedicels with pubescent calyces and longer corolla tubes.

Type.

Guatemala. Baja Verapaz: Union Barrios, 15°11'01"N, 090°12'16"W (DMS), 1630 m,11 Mar 1972, E. Contreras 11234 (holotype: F-1942896; isotype: MO).

Description.

Shrubs, 1-7 m. Leaf-bearing stems drying pale red-brown or tan, the internodes 2-34 × 1.5-3.5 mm; young stems glabrous, occasionally sparsely pubescent, where pubescent the hairs 0.375 mm, simple, appressed, crooked and frequently glandular. Axillary buds 1.25-2.0 mm, frequently absent, drying dark brown, densely pubescent and glandular, not subtended by a minor leaf. Lamina 13-135 × 6-42 mm, length to width ratio 1.5-3.6, obovate, elliptic to ovate, coriaceous, drying olive green, brown or yellow-green above; the upper surface glabrous or very sparsely pubescent, the hairs 0.125 mm, simple, weakly appressed, crooked, occasionally sparsely glandular, primary only or primary and secondary veins clearly visible to the naked eye, only the primary veins raised; the lower surface glabrous, sparsely punctate glandular, primary only, primary and secondary or primary to tertiary veins clearly visible to the naked eye, primary only or primary and secondary veins raised, secondary veins 3-6 pairs, borne 45-75° to the midrib, weakly curved, the veinlets not visible; base decurrent, cuneate, or acute, occasionally asymmetrically so; margin entire; apex acute or subcuspidate; petioles borne on a woody or crescent-shaped spur or regularly from the stem, 5-66 × 0.75-1.25 mm, drying dark purple, dark brown, yellow-green or green, glabrous, occasionally sparsely punctate glandular. Inflorescences 6-13 per herbarium sheet, terminal, subterminal or borne along the full length of the leaf-bearing portion of the stem, axillary panicles solitary in each axil, 25-60 mm long, bearing 1-16 flowers in 1-3 fascicle-like clusters, each cluster bearing 1-5 flowers; peduncle 1.5-20.0 × 0.75-1.75 mm, yellow-brown through orange-brown to dark brown, glabrous tosparsely or very sparsely pubescent, the hairs 0.25 mm, simple, curved or straight, occasionally glandular; bracts 18-43 × 9-13 mm, leaf-like; bracteoles 4-22 mm, ovate, linear, glabrous or sparsely pubescent. Flowers pedicellate, the pedicels 0.5-1.5 mm; calyx 5-6.5 × 2.0-2.5 mm, the outer surface glabrous, the lobes 4-6, 1.25-2.5 mm long, erect; corolla yellow-green or pale yellow to yellow, 4-26 mm long, the tube 9.0-21.5 mm long, 2.5-4.25 mm in diameter at the mouth, 0.75-1.50 mm in diameter at the base, glabrous, the lobes 4-6, 3.5-5.5 mm long; stamens 5, the filaments 16-19 mm, equal, adnate for 6-9 mm, pubescent from insertion point to the base, with a 1-lobed keel-shaped or reduced knee-like appendage present at insertion point, the anthers 1.0-1.5 × 0.675-1.0 mm; style 11-18 mm, the stigma 0.5-1.0 × 1-2 mm. Infructescences 10-65 mm long, bearing 2-6 fruit; fruiting calyx 3.5-7.5 × 6-9 mm; fruit 7-10 × 4-7 mm, subglobose to oblongoid, white when ripe. Seeds 1-10, 3-6 × 1.5-3.5 × 2-3 mm.

Etymology.

After Elias Contreras, Guatemalan plant collector and botanist who collected the type and two of the paratype collections of this species.

Distribution.

Montane or cloud forest, often undisturbed forest. Existing collection localities suggest that Cestrum contrerasianum is distributed along the Pacific drainage of central Guatemala (Baja Verapaz, El Quiche, Huehuetenango) and southeastern Mexico (Chiapas) in an area encompassing ca. 13,400 km2 ( Google Earth, accessed 10 Dec 2010).

Discussion.

Of the sixteen known collections of Cestrum contrerasianum ,ten were previously determined as Cestrum aurantiacum Lindl. Comparison of the holotype and paratype material with type specimens from the herbaria listed in the Materials and methods section recovered Cestrum contrerasianum as most similar to Cestrum formosum C.V. Morton. It can be distinguished from those species on the basis of inflorescence number and morphology and flower and fruit morphology as summarised in Tables 3 & 4 .

Conservation status.

Using IUCN criteria ( IUCN 2001) Cestrum contrerasianum is considered Vulnerable (VU B1ab(iii)) based on subcriteria B1 based on an Extent of occurrence <20,000 km2, a severely fragmented range and continuing decline in the area of habitat.

Paratypes.

GUATEMALA. Baja Verapaz: Union Barrios, W of km 154, 15°11'01"N, 090°12'16"W (DMS), 1600 m, Aug 17 1975, C. L. Lundell & E. Contreras 19671 (F); Niño Perdido, La Cumbre de San José Espinero, 15°07'54"N, 090°09'46"W (DMS), 18 May 1977, C. L. Lundell & E. Contreras 20913 (CAS, F). Huehuetenango: Cerro Huitz, between Mimanhuitz and Yulhuitz, Sierra de los Cuchumatanes, 15°51'18"N, 091°19'28"W (DMS), 1500-2600 m, 14 Jul 1942, J. A. Steyermark 48657 (F); vicinity of Nucapuxlac, 2500 m, 17 Jul 1942, J. A. Steyermark 48943 (AA, F). El Quiché: about 7 km SWW of Nebaj, 2200 m, Jun 22 1964, E. Contreras 5088 (LL). MEXICO. Chiapas: Municipio of San Cristóbal las Casas, 2 miles northeast of Highway 190 along the old road to Huistán, 2300 m, 22 Jan 1965, D. E. Breedlove & P. Raven 8294 (US); Municipio of Tenejapa, along the river of Chik Ha', barrio of Yashanal, paraje of Matsab, 1700 m, 17 Jul 1965, D. E. Breedlove 11109 (F); Municipio La Trinitaria, Lagos de Montebello, 42 km northeast of La Trinitaria, 16°07'05"N, 091°42'27"W (DMS), 1300 m, 23 Oct 1971, D. E. Breedlove & R. F. Thorne 21152 (DS); Municipio of Comitán de Dominguez, 5 km north of Highway 190 on a logging road from Laguna Chamula microwave station, 2400 m, 15 Oct 1976, D. E. Breedlove & B. Bartholomew 40775 (DS); Municipio of La Independencia, third ridge along logging road from Las Margaritas to Campo Alegre, 2300 m, 24 Oct 1976, D.E. Breedlove 41079 (DS); Municipio of Comitán de Dominguez, Laguna Chamula microwave station, 4 km southwest of Highway 190 between Comitán and Amatenango del Valle, 2500 m, 6 Nov 1981, D. E. Breedlove & G. Davidse 54848 (CAS); San Felipe village, near Ciudad San Cristobal las Casas, Mount Ecatepec, 3 miles W of village, 2400 m, Mar 31 1949, M. C. Carlson 1614 (F); Municipio of San Cristóbal las Casas, a 200 m del Paraje K'ostic, 16°43'20"N, 092°31'29"W (DMS), 2300 m, 5 Sep 1994, A. Chamé & A. Luna 352 (CAS); temperate land, 1864-70, A. B. Ghiesbreght 837 (GH); Municipio of San Cristóbal las Casas, Cerro El Extranjero, 16°39'39"N, 092°34'26"W (DMS), 2350 m, 26 Mar 1992. M. González E., P. F. Quintana A., M. Martínez I. & N. Ramírez M. 1769 (CAS).

Figures

Figure 3. Cestrum contrerasianum A. K. Monro A Flowering stem B Style C Longitudinal section through the corolla showing stamen arrangement D Flower with apex of corolla lobe highlighted. Drawn from E. Contreras 11234 (F).