A New Subgenus and Fifteen New Species of Echeandia (Anthericaceae) from Mexico and the United States

Abstract

Two subgenera in Echeandia (Anthericaceae), i.e., subg. Echeandia and subg. Mscavea, are recognized based on time of flower opening, tepal shape, flower color, and habitat differences. Fifteen species are proposed. One, E. texensis, is based on four collections made near Brownsville, Texas, and is surely rare, possibly extirpated. The recognition of five species clarifies the distributional range of E. reflexa, a common species of eastern Mexico. Seven species are endemic to Guerrero and adjacent areas of Michoacin, Mexico, Morelos, and/ or Oaxaca. A key to the species of subgenus Mscavea and white-flowered species of subgenus Echeandia is provided. Echeandia, as described by Ortega (1800: 135, tab. 18), included New World species with connate anthers and scaled filaments. These traits effectively separated Echeandia and Old World Anthericum, which had free anthers and smooth or papillate filaments. With few exceptions, New World species with free anthers were included in Anthericum for the next 180 years. However, during that time, species with smooth filaments were included in Echeandia (see Weatherby, 1910), and species with scaled filaments were described in Anthericum (Baker, 1876; Greenman, 1898). Thus, for the past century or more, New World Anthericum and Echeandia were separated simply on the nature of their anthers, and the unique traits they shared were ignored. Because most New World species described in Anthericum and Echeandia share traits that are unique in Anthericaceae, including a corm and scaled filaments, they are now included in Echeandia (see Cruden, 1987, 1994), which, with 78 described species, is the second largest genus in Anthericaceae (see Chase et al., 1996; Dahlgren et al., 1985: 186). Excluded from Echeandia are approximately 20 white-flowered South American species with smooth filaments and free anthers that probably constitute an undescribed genus. Within Echeandia there are two distinct lineages, and each includes species with free anthers and others with connate anthers. The two lineages share at least two synapomorphies. First, all Echeandia have a corm that produces new storage roots and inflorescences yearly. Other Anthericaceae are rhizomatous, and only the terminal segment produces leaves and inflorescences. There is no evidence that a segment produces inflorescences in successiv years. Second, most genera in Anthericaceae s. str. have smooth and/or papillate filaments, e.g., Chlorophytum s.1. (Kativu & Nordal, 1993) and Hagenbachia (Cruden, 1987), whereas most Echeandia (63/78) have scaled filaments and those with smooth filaments occur in derived groups. In addition, anthers adapted for pollination by vibratory bees occur in both lineages and are unique in Anthericaceae s. str. In the white-flowered lineage the anthers in 21 of 25 species are connate and form a cone, and in the other 4 species the individual anthers are adapted for buzz pollination (see below). In the yellow-flowered lineage, 19 of 53 species have anther cones and in 4 additional species the individual anthers are adapted for buzz pollination. The filaments of all these species are inserted dorsally within a basipetally opening pocket, which effectively holds the anther on the same axis as the filament and probably provides the structural stability needed to support a bee while it vibrates an anther or anther cone. It is possible that connate anthers constitute a parallel apomorphy. In other Echeandia and most other Anthericaceae, the anthers are free, usually versatile, dorsifixed, and dehisce laterally. In most Chlorophytum, however, the filaments are inserted more or less basally in a deep pit, which restricts the movement of the anthers. Finally, relative to Echeandia's putative ancestor, both lineages combine a mixture of primitive and derived traits. Based on other Anthericaceae, that ancestor had white flowers, which probably opened relatively early in the morning, broadly elliptical tepals, smooth filaments, and versatile anthers that dehisced laterally. Thus, yellow flowers are apomorphic in one lineage, as are narrowly elliptical inner tepals and late opening flowers in the other. Thus, the available data are consistent with a common ancestor diverging into two lineages, which are formally recognized below as subgenera. NovoN 9: 325-338. 1999. This content downloaded from 207.46.13.124 on Sun, 11 Sep 2016 04:55:57 UTC All use subject to http://about.jstor.org/terms