Erythrostemon guevarafeferii J.L.Contreras, S.Sotuyo & G.P.Lewis, 2017

Sotuyo, Solange, Contreras-Jimenez, Jose Luis & Lewis, Gwilym P., 2017, A new species of Erythrostemon (Leguminosae, Caesalpinioideae) from the western Rio Balsas Depression, Mexico, PhytoKeys 76, pp. 31-38 : 31-33

Erythrostemon guevarafeferii J.L.Contreras, S.Sotuyo & G.P.Lewis sp. nov. Figure 1

Type.

México, Michoacán. Cerca de la cortina de la presa El Infiernillo J.L. Contreras 3111 (Holotype: MEXU; Isotypes: FCME, K, MEXU) .

Erythrostemon hintonii affinis sed glabra, structuris floralibus omnino glanduliferis, foliis minoribus cum minus foliolis fasciculatus in dimidio superiore rhachidis pinnae, floribus brevioribus, sepalis laete ochraceis et petalis salmoneis, pedicellis articulatis in dimidio superiore longitudinis, legumine omnino glabro et stipitatis glandulis rubris obducto. Etiam differt inflorescentias arcuatas et pendulas cum pedicellis florum gracilibus, fere horizontalibus vel reflexis, tortis itaque floribus resupinatis.

Similar to Erythrostemon hintonii , but glabrous, all flower structures glandular, leaves smaller with fewer leaflets, flowers shorter, sepals light yellow-ochre and petals salmon coloured, pedicels articulated at, or above, their middle, legume completely glabrous and with stipitate red glands. Also differing in the curved and/or pendulous inflorescences with the flowers on slender, horizontal or reflexed, twisted pedicels that render them resupinate.

Description.

Small tree or shrub, 2-6 m tall, bark grey pruinose, exfoliating, young branches reddish grey pruinose. Leaves bipinnate, (7.5-) 10-20 (-22) cm long; stipules triangular-acuminate, caducous, 2-3 × 1.2-1.5 mm, margin with red stipitate glands, white hairy on both surfaces; petiole (2-) 3.0-6.5 (-7.3) cm long, pubescent or glabrescent when mature; rachis (3-) 5.0-14.5 (-15.7) cm long, indumentum similar to that of the petiole; pinnae (5-) 7-13 per leaf, (1.6-) 2-6 (-7.7) cm long, densely pubescent when young, glabrescent when mature; leaflets (3) 4-7 (-10) jugate, clustered on the upper half of the pinnae rachises, obovate, elliptic or oblong-elliptic (6-) 10-20 (-25) × (4-) 5-11 (-13) mm, base rounded, slightly oblique, margin entire and lacking glands, or with sunken black punctate glands that render the margin slightly crenulate, apex obtuse to rounded, pubescent or glabrescent at maturity. Inflorescence an erect or pendulous (the peduncles curved downwards), terminal or axillary raceme or panicle (with few branches near the base), (6-) 10-36 cm long, densely white pubescent, and with red glands; bracts ovate-caudate, caducous, (2.5-) 3.2-5.0 (-5.7) × (1-) 1.3-2.0 (-2.3) mm, margin with or without glands, densely white pubescent on both surfaces; pedicels slender, erect-patent, (6-) 7.5-11.0 (-16.5) mm long, articulated at or above the middle, densely white pubescent, sometimes twisted, so that the flowers are resupinate (although then presented with the median petal uppermost on the pendulous inflorescences). Calyx light yellow-ochre, densely pubescent, tube obliquely obconic, laterally compressed, (4.3-) 4.7-6.0 × (2.1-) 2.5-3.5 (-4) mm; adaxial sepals ovate to oblong-ovate, 5.5-7.0 × 2.5-4.1 mm, slightly concave, the lateral sepals oblong-ovate, 5.4-7.0 mm × 2.7-4.0 mm; abaxial sepal cymbiform, (5.7-) 6-7.2 (-7.4) × (3.6-) 3.8-5.0 mm, all sepals with an entire margin, glandular ciliate and with an acute apex, puberulent on adaxial surface; petals salmon-coloured, clawed; adaxial petal ovate, 5.2-7.5 × 3.5-5.5 mm, base cordate, margin entire, apex obtuse, rounded, with stipitate glands near the claw apex on the abaxial surface, pilose on the adaxial surface; claw 1.8-3.0 mm long, sigmoid curved, ciliate, pilose and glandular-stipitate on abaxial surface or glabrous and sparsely stipitate-glandular; lateral petals ovate, 5.6-7.5 (-8) × 4.2-6 (-6.5) mm, base obtuse, margin glandular ciliate up to ⅕ of its length, apex rounded or obtuse, stipitate-glandular on abaxial surface, the abaxial petals ovate (6-) 6.5-8.5 × 3.7-5.5 (-5.7) mm, base oblique, margin entire, glandular ciliate from the base up to ⅕ of their length, apex obtuse, the claw ciliate and pilose on its abaxial surface; stamens curved, filaments (6.5-) 7.5-9.5 (-10) mm long, flattened at the base, densely villous to ¾ of their length, the upper third with lime green stipitate glands; anthers oblong-elliptic, (1.2-) 1.3-1.8 × (0.8-) 0.9-1.2 (-1.3) mm, erect at anthesis; ovary (1.7-) 2-3 (-3.5) mm long borne on a stipe 0.5 mm long, densely sericeous and with green cupuliform glands (or these absent); style curved, of different lengths in individual flowers, either short, 2.5-3.5 mm long, or well developed and 4.0-6.5 mm long, pilose for ½ of its length from base; stigma porate laterally; ovules 2 (-3) per ovary. Legume falcate, (3.7-) 4.3-5.7 × 1.1-1.7 cm, chartaceous, brown-yellow to vinaceous, densely to sparsely pubescent or glabrous when mature, with red stipitate glands or these glands absent, sutures densely pubescent, elastically dehiscent; seeds 1-2 (-3) per fruit, obovate, (8.6-) 9.5-10.5 (-11) × 7.5-9.6 × (1.7-) 1.9-2.2 (-2.4) mm, olive-brown, nitid.

Habitat.

Seasonally dry tropical forest on rocky slopes, locally common in secondary vegetation along roads, on alluvial soils near seasonal or permanent streams.

Distribution and phenology.

Known only from the western region of the Río Balsas Depression, in the states of Guerrero and Michoacán. Flowering from February to April and in fruit from February to May.

Selected specimens examined. MÉXICO. Michoacán: Municipio de Arteaga: El Infiernillo, cerca de la cortina de la presa: Nuñez & Silva 3905 (MEXU); J.C. Soto 1331 & S. Zárate (MEXU); J.C. Soto 3694 (MEXU); Sotuyo et al. 41,46,47,48 (K, MEXU); 23 km por el camino a Infiernillo a partir de la carretera Apatzingan-Lázaro Cárdenas: J.L. Contreras 2060, 2838 (MEXU). Municipio de Nocupétaro: San Antonio de los Muertos; J.C. Soto 3905 & G. Silva (MEXU). Guerrero: Municipio de la Unión: 5 km al S de Colmeneros, camino a Coahuayutla: J.L. Contreras 2371, 2372 (FCME); Cerro Prieto, 12 km al E de la Garita: J.L. Contreras 2388 (FCME); Zihuatanejo, 85 km aprox. NW, on road 22 km to N of La Unión and 7 km to N of Las Juntas del Río towards Santa María: D.J. Macqueen & A. Nileshwar 446 (K).

IUCN Red List category.

We recommend that Erythrostemon guevarafeferii be given a conservation assessment of Vulnerable [VU (B1b-iii)], in accordance with IUCN (2012) categories and criteria. The extent of occurrence (EOO) of Erythrostemon guevarafeferii is estimated to be over 2424.18 km2, well below the 20,000 km2 upper limit for Vulnerable status under criterion B1, but its area of occupancy (AOO) is estimated to be less than 10 km2 (the limit for Endangered status under criterion B2). The species is currently known from three discontinuous populations in the states of Michoacán and Guerrero, these separated by differing habitat type, human settlement and agricultural land. Erythrostemon guevarafeferii is known in only one protected area, the Reserva de la Biosfera Zicuirán-Infiernillo in Michoacán. The preferred habitat of the species is potentially threatened by future settlement and agricultural activities, as well as by environmental problems associated with drug trafficking organizations.

Etymology.

The species epithet is dedicated to Fernando Guevara Fefer who recently passed away. Friend, botany teacher and researcher at the Universidad Michoacana de San Nicolás de Hidalgo, he was interested in the genus Bursera and in floristic and vegetation studies within Michoacán, particularly in the Infiernillo region where the type specimen was collected.

Figures

Figure 1. Erythrostemon guevarafeferii, a bipinnate leaves b leaflet upper surface showing marginal glands c inflorescence with immature fruits developing at base d flower e adaxial (median) petal f lateral petal g abaxial petal h gynoecium i stamens j calyx k fruit showing the red stipitate glands as black dots. (a - j drawn from Contreras-Jimenez et al. 3111, holotype MEXU k from Contreras-Jimenez 2860). Drawn by Albino Luna.