Harpalyce yucatanense Miranda ex São-Mateus & M. Sousa, 2018

São-Mateus, Wallace M. B., Sousa, Mario, Cardoso, Domingos & Queiroz, Luciano Paganucci De, 2018, Two new Mesoamerican species of Harpalyce (Leguminosae, Papilionoideae), Phytotaxa 344 (2), pp. 160-168 : 163-166

Harpalyce yucatanense Miranda ex São-Mateus & M. Sousa , sp. nov. ( Figs. 2‒3 )

This species is morphologically similar to Harpalyce arborescens Gray (1861: 178) , but it differs by the inflorescence longer than the subtending leaf, triangulate bracteoles less than 1 mm long, flowers ca. 4 cm long, and ovary 0.8‒0.9 cm long and pilose only along the vexillar margin (vs. inflorescence smaller than the subtending leaf, linear bracteoles 3‒5 mm long, flowers less than 2 cm long, and ovary 0.5‒0.6 cm long and glabrescent).

Type: ― MEXICO. Quintana Roo: Cozumel, a 4 km al N de la carretera transversal, sobre el camino a La Zona Arqueológica de San Gervacio, Isla de Cozumel, 18 June 1985 (fl), E. Cabrera & H. de Cabrera 8687 (holotype: MEXU!, isotype: XAL!).

Trees 6‒12 m tall, branches with conspicuous, rounded, and cream lenticels; petiole, leaf rachis, pulvinules and inflorescence axes ferruginous-tomentose with golden, erect hairs, mostly when immature or sometimes glabrescent when mature. Stipules not seen. Leaves (8‒) 10.5‒14 cm long, imparipinnate; petiole 1.3‒3.2 cm long, slender; rachis 4.5‒10.5 cm long, interfoliolar segments 1‒2.5 cm long; leaflets (7‒)9‒13(‒15), opposite, sometimes slightly alternate, chartaceous to subcoriaceous, brochidodromous, midvein prominent on lower surface and strongly sulcate on upper surface, secondary veins 6‒9 pairs, inconspicuous to slightly conspicuous, tertiary veins tenuously reticulate, concolor, light-green, yellowish, globose peltate glands present only on the lower surface, margins entire and revolute, upper surface puberulent when immature, glabrous or glabrescent at maturity, lower surface densely pubescent and tomentose along the midvein or densely tomentose, pulvinules 2.5‒5 mm long, lateral leaflets usually larger towards the leaf apex, (1.6‒)2.2‒4.5(‒6) × 1‒2.5 cm, oval, oval-elliptic to oblong-elliptic, base rounded to truncate, apex retuse, distal leaflet 2‒5(‒6) × 1.5‒2(‒2.5) cm, shape similar to the lateral ones. Inflorescences longer than the subtending leaf, 10‒20- flowered, axillary racemes (6‒) 8.5‒13 cm long, or terminal panicles 15‒20 cm long; bracts 1‒1.5 × 0.8 mm, lineartriangular, densely pubescent with golden hairs; pedicels 0.8‒1.4 cm long, tomentose with golden hairs; bracteoles ca. 0.8 × 0.8 mm, caducous, attached at the base of calyx, triangular, densely pubescent with golden hairs; flower bud 1.2‒2.4 × 0.4‒0.6 cm, oblong, apex falcate and acute. Flowers ca. 4 cm long, asymmetrical, papilionaceous, non-resupinate; calyx outer surface densely tomentose, the inner surface glabrous, strongly bilabiate, the vexillar lip 2.4‒3 × 0.6‒0.8 cm, oblong-elliptic, carinal lip 2.8‒3.1 × 0.6‒0.7 cm, oblong-lanceolate; petals membranaceous, glabrous; vexillum 2.2‒4 × 1.6‒2.8 cm, pink turning into white when dry, widely ovate, basally attenuate-auriculate, auricles ca. 1 × 1 mm, inflexed, apex rounded, claw 1.8‒3.6 cm long; wing petals 2.2‒2.5 × 0.6‒0.7 cm, light-pink, oblong-obovate, basally retuse, auriculate on both sides, the vexillar auricle 3‒3.5 × 1.5 mm, apex acute, the carinal auricle ca. 1.2 × 1 mm, apex widely oblique, claw ca. 2.2 cm long; keel petals 2.2‒2.6 × 0.3‒0.4 cm, light-pink, oblong-falcate, connate from the base except for the claw, base auriculate on the vexillar margin, auricle ca. 1.5 mm long, deltate, apex obtuse, claw ca. 2 cm long; stamens 10, ca. 2.5 cm long, pseudomonadelphous, fused into a staminal tube deeply divided along the vexillar side, incurved, filaments free at apex for 1.1‒1.3 cm, anthers oblong, dimorphic, alternately short and long, the larger ones 3‒4 × 1 mm, basifixed, the smaller ones ca. 2 × 0.5 mm, dorsifixed; gynoecium 2.8‒3 cm long, ovary 0.8‒0.9 cm long, sessile, oblong, erect, 8-ovulate, mostly glabrous except for the pilose indumentum of yellowish, erect hairs along the vexillar margin, style ca. 1.8 cm long, pilose only in the basal portion of the vexillar margin, filiform, curved, stigma capitate, pubescent. Legumes 7.6‒11.3 × 2.2‒2.9 cm, elastically dehiscent, compressed, oblong-obovate, base truncate, apex cuspidate, cusp 1‒2 mm long, glabrous, margins sinuous in the middle portion, septa absent or inconspicuous, valves coriaceous, green turning into black when dry, reticulate when young. Seeds 6‒7, ca. 1 × 1 cm, compressed, widely-ovate, reddish; strophiole gristly.

Etymology: ―The epithet “ yucatanense ” refers to its distribution in the Yucatan Peninsula.

Distribution and habitat: ―The new species has been recorded only for the Mexican states of Quintana Roo and Yucatan, both located in the Yucatan Peninsula. It grows in semi-evergreen tropical forest with mean annual rainfall ranging from 1100 to 1300 mm ( Pennington & Sarukhán 2005), where its habitat is usually associated with rocky outcrops at elevations of up to 200 m, with the vegetation harboring large trees reaching up to 35 m tall.

Phenology: ―The species was found flowering in January and from April to June. Fruiting specimens were seen from November to January, but also in May.

Conservation status: ― Harpayce yucatanense is considered Vulnerable (VU) following the criterion B1a ( IUCN 2012) and the estimated extent of occurrence of 18,245 km 2 ( Bachman et al. 2011). Although this species is locally rather common, its distribution range is restricted to an area of occupancy of 16 km 2 and in only four locations separated by 70‒160 km in the states of Quintana Roo and Yucatan.

Additional specimens examined (paratypes): ― MEXICO. Quintana Roo: Felipe Carrilo Puerto: a 3 km al NE de Felipe Carrillo Puerto, por el camino hacia Vigía Chico , 12 January 1980 (fr), O. Téllez & E. Cabrera 1291 (MEXU) ; a 3 km oeste de F. Carrilo Puerto, rumbo a Vigía Chico , 16 November 1980 (fr), E. Cabrera & L. Cortês 415 (MEXU) ; a 8 km de la carretera Chetumal - Felipe Carrillo Puerto , sobre el camino a El Placer, 12 January 1980 (fr), O. Téllez & E. Cabrera 1276 (MEXU) ; a 12 km al NE de Felipe Carrillo Puerto, sobre el camino a Vigía Chico , 26 January 1983 (fr), E. Cabrera & H. de Cabrera 4378 (MEXU) ; a 31 km al NO de Felipe Carrillo Puerto, sobre el camino a Vigía Chico , 19 December 1982 (fr), E. Cabrera & H. de Cabrera 4063 (MEXU) ; 2 km al NE de Carrillo, Mpio. Felipe Carrillo Puerto , 17 January 1984 (fr), R. Durán & I. Olmsted 745 (MEXU) ; 2 km al NE de F. Carrillo Puerto, Mpio. Felipe Carrillo Puerto , 17 January 1984 (fr), R. Durán & I. Olmsted 754 (MEXU) ; 3 km el noroeste de Felipe Carrillo Puerto , 27 January 1985 (fl), R. Durán et al. 1269 (MEXU, XAL) ; Mpio de Felipe Carrillo Puerto, 8‒10 km al NE de Felipe Carrillo Puerto, sobre el camino a Vigía Chico, 15 April 1989 (fl), E. Cabrera & W. Colli 16395 (MEXU, XAL). Isla de Cozumel : a 4 km al SE de la desv. Al Cedral, por la costera S Isla de Cozumel , 04 June 1986 (fl), E. Cabrera & H. de Cabrera 11444 (MEXU) ; 1 km al norte de la carretera transversal por el camino a la zona arqueológica de San Gervacio , 03 June 1986 (fl), E. Cabrera & H. de Cabrera 11367 (MEXU) ; 4 km al norte de la carretera transversal, sobre el camino a la zona Arqueológica de San Gervacio , 25 November 1986 (fr), E. Cabrera & H. de Cabrera 9862 (MEXU) . Yucatan: Sudzal , 21 April 1956 (fl, fr), O. G. Enriquez 565 (MEXU) ; Ticul , 02 May 1956 (fl, fr), O. G. Enriquez 582 (MEXU) .

Discussion: ― Harpalyce yucatanense is morphologically related to H. arborescens , both having arboreal habit, chartaceous to subcoriaceous leaflets with ovate to ovate-elliptic or oblong-elliptic blades, and reddish seeds. Indeed, Arroyo (1976) adopted a broad circumscription for H. arborescens , in which she included some specimens herein newly referred to H. yucatanense (e.g. Enriquez 565 [MEXU]). The limited number of herbarium materials studied by Arroyo (1976) for the taxonomic revision of Harpalyce might explain why several Mesoamerican species (e.g. H. arborescens and H. formosa ) actually involve a complex of distinct cryptic species. The first two authors had the opportunity to understand species variation in the field and after a more comprehensive analysis of many recent MEXU collections of the genus. Accordingly, Arroyo’s description of flower (petal) length should be seen with caution. For example, the described morphological variation for H. arborescens is not accurate because of the misidentification of particular, unrelated specimens (e.g. those newly referred here to a new species) into a broad, heterogeneous description.

Here we differentiate H. yucatanense mainly by the tomentose, clavate flower buds with acute apex and measuring ca. 3 cm long (vs. flower buds ca. 1 cm long, straight, the apex rounded, and densely covered by woolly indumentum in H. arborescens ), the larger, ca. 4 cm long flowers (vs. less than 2 cm long), ovary pilose only along the vexillar margin (vs. entirely glabrescent), and legumes measuring 7.6‒11.3 cm long (vs. 4.8‒7.5 cm long). Additionally, their distribution ranges do not overlap. Whereas H. yucatanense is restricted to the Yucatán Peninsula, H. arborescens is widespread along the eastern coast, in the states of Querétaro, Vera Cruz, San Luis Potosi, and Tamaulipas.

Harpalyce yucatanense had already been identified as new, but not published, in 1956 by the Spanish botanist Dr. Faustino Miranda, an important researcher at the Instituto de Biología of Universidad Nacional Autónoma de México (UNAM), who studied the Mexican vegetation and described several new plant species. He annotated the name H. yucatanense in the specimen Enriquez 565.

Figures

FIGURE 2. Harpalyce yucatanense. A. Flowering and fruiting branch. B. Floral bud. C. Bracteole. D. Vexillum. E. Wing petal. F. Keel petal. G. Closed staminal tube. H. Open staminal tube. I. Gynoecium in the center of the calyx. J. Detail of ovary and style. (A. From O.G. Enriquez 582, MEXU; B‒J. From E. Cabrera & H. de Cabrera 8687, MEXU). Drawn by Ramiro Cruz.

FIGURE 3. Distribution range of the two species of Harpalyce described here: ▲ H. torresii (Belize and Mexico) and ● H. yucatanense (Mexico).