ABSTRACT
Our knowledge of the systematics of the papilionoid legume tribe Brongniartieae has greatly benefitted from recent advances in molecular phylogenetics. The tribe was initially described to include species marked by a strongly bilabiate calyx and an embryo with a straight radicle, but recent research has placed taxa from the distantly related core Sophoreae and Millettieae within it. Despite these advances, the most species-rich genera within the Brongniartieae are still not well studied, and their morphological and biogeographical evolution remains poorly understood. Comprising 35 species, Harpalyce is one of these poorly studied genera. In this study, we present a comprehensive, multi-locus molecular phylogeny of the Brongniartieae, with an increased sampling of Harpalyce, to investigate morphological and biogeographical evolution within the group. Our results confirm the monophyly of Harpalyce and indicate that peltate glandular trichomes and a strongly bilabiate calyx with a carinal lip and three fused lobes are synapomorphies for the genus, which is internally divided into three distinct ecologically and geographically divergent lineages, corresponding to the previously recognized sections. Our biogeographical reconstructions demonstrate that Brongniartieae originated in South America during the Eocene, with subsequent pulses of diversification in South America, Mesoamerica, and Australia. Harpalyce also originated in South America during the Miocene at around 20 Ma, with almost synchronous later diversification in South America and Mexico/Mesoamerica beginning 10 Ma, but mostly during the Pliocene. Migration of Harpalyce from South to North America was accompanied by a biome and ecological shift from savanna to seasonally dry forest.
Subject(s)
Fabaceae , Phylogeny , Fabaceae/genetics , Grassland , Forests , Ecosystem , Bayes Theorem , PhylogeographyABSTRACT
Two new species of Harpalyce are described from Cuba, H.revolutasp. nov. from a serpentine area in the northern part of E. Cuba and H.marianensissp. nov. from calcareous areas in the southern part of E. Cuba. Both have relatively small flowers, with an up to 6 mm long standard, and 2-3 mm long wings. Harpalycemarianensis is further characterized by strongly suberous (corky) young branches of a spongy consistence, deeply furrowed longitudinally, and by leaflets covered with a particular type of orange, apparently disk-shaped, sessile glands abaxially. Harpalycerevoluta, moreover, has suborbicular or broadly elliptic leaflets with a strongly recurved or sometimes revolute margin, secondary veins inconspicuous on either side; the foliar glands, by their morphology and anatomy, are of a different type. An epitype is designated for the name Harpalyce and its type, H.formosa; the distribution of both new species and their close relatives is mapped, and an updated identification key is offered, to cater for all 16 currently recognised Cuban species.
ResumenSe describen dos nuevas especies de Harpalyce para Cuba oriental, H.revolutasp. nov. de las áreas de serpentina del norte y H.marianensissp. nov. de áreas de formaciones calcáreas del sur. Ambas se caracterizan por tener flores pequeñas, con estandarte de hasta 6 mm de largo y alas de hasta 3 mm de largo. Harpalycemarianensis se distingue además por sus ramas jóvenes fuertemente suberosas, de consistencia esponjosa, profundamente surcadas longitudinalmente, y los folíolos cubiertos abaxialmente por un tipo particular de glándulas sésiles anaranjadas. Harpalycerevoluta, por su parte, tiene folíolos suborbiculares o anchamente ovales, con margen fuertemente recurvado o hasta revoluto, con venas secundarias inconspicuas en ambas caras, y glándulas foliares, por su morphología y anatomía, son de un tipo distinto. Se designa un epitipo para el nombre Harpalyce y su tipo, H.formosa. Se presenta un mapa de distribución de las nuevas especies y las relacionadas con ellas y se ofrece una clave de identificación actualizada, que incluye las 16 especies cubanas actualmente reconocidas.