Thomas B. Croat

Phylogenomics of the plant family Araceae

The biogeography, chromosome number evolution, pollination biology and evolutionary history of the plant family Araceae have recently become much clearer (Cabrera et al., 2008; Chartier et al., 2013; Cusimano et al., 2011, 2012; Nauheimer et al., 2012). However, phylogenetic ambiguity near the root of the tree precludes answering questions about the early evolution of the family. We use Illumina sequencing technology and reference based assembly to resolve the remaining questions in the deep phylogeny of Araceae. We sampled 32 genera and obtained 7 from GenBank (including an outgroup), representing 42 of 44 major clades described in Cusimano et al. (2011). A subsequent phylogenomic analysis based on mitochondrial data was performed to test congruence between plastid and mitochondrial data for phylogenetic inference. Plastid sequences produced strongly supported phylogenies. In contrast, mitochondrial phylogenies were weakly supported and incongruent with chloroplast data (Templeton test, p⩽0.0001), although several smaller clades were recovered. New strongly-supported clades seen here are: (1) Anubias and Montrichardia, excluding Calla, form a clade that is sister to the Zantedeschia clade; (2) the South African genus Zantedeschia is sister to the Old World Anchomanes clade; and (3) within the Zantedeschia clade, Philodendron is sister to the rest. Calla and Schismatoglottis form a clade at the base of one of two major clades in Aroideae based on complete chloroplast sequences. Although statistical support is weak, morphological and cytological features support this topology.

A Molecular Phylogeny of the Species-Rich Neotropical Genus Anthurium (Araceae) Based on Combined Chloroplast and Nuclear DNA

Abstract Anthurium is a strictly Neotropical genus of Araceae ranging from southern Mexico to northern Argentina, including approximately 900 accepted species names. Despite its immense diversity, its ecological importance in Neotropical forests, and a long history of botanical collection, cultivation, and taxonomical research, Anthurium has been only cursorily sampled in previous molecular phytogenies. This study aims to test the monophyly of Anthurium, to understand the evolutionary history of the genus, and to elucidate relationships among its species using maximum parsimony, maximum likelihood and Bayesian analyses on a combined chloroplast (trnG intron, tmH-psbA and tmC-ycf6 intergenic spacers) and nuclear (CHS first intron and partial flanking coding regions) DNA sequence dataset for 102 Anthurium species and closely related outgroups. Despite some limitations (ca. 11% species richness coverage, and lack of nuclear sequences for outgroups), results indicate that Anthurium is a strongly supported monophyletic genus and that at least 18 major supported clades are recognizable within it, most of them easily characterized morphologically and/or geographically. This study also suggests that the current sectional classification of Anthurium does not accurately represent its evolutionary history since most of the major clades recovered in these analyses do not correspond with the current circumscriptions of infrageneric groups. Despite using the most variable gene regions available, low sequence divergence was found among Anthurium species, relatively short branches characterize the core of the Anthurium clade, and resolution is still lacking in the deeper nodes of the phylogeny, a pattern consistent with a rapid, and probably recent, radiation of species.

Geographical affinities of The Barro Colorado Island Flora

The flora of Barro Colorado Island was examined for affinities with the floras of Central and South America. Trees, lianas, and epiphytes were treated as separate groups. Distributional classes were established, ranging from species endemic to Panama and those with distributions including both Central and South America as well as the West Indies. The Barro Colorado flora seems to consist of approximately equal numbers of both North (chiefly Central) and South American species. Twelve percent of the Barro Colorado Island species considered in this study are endemic to Panama, and 11% are restricted to Panama and to nearby regions of Colombia and Costa Rica. Trees, lianas, and epiphytes are endemic in roughly an inverse proportion to their ability to be wind-dispersed, with trees showing the highest level of endemism and also having the least significant wind dispersal. About 50% of all species in the study are common to both North and South America, indicating a significant migration of species from both directions. The evidence indicates that most migrations between North and South America were Late Tertiary.

Resurrection and New Species of the Neotropical Genus Adelonema (Araceae: Philodendron Clade)

Abstract Previous studies have shown Homalomena as traditionally defined to be polyphyletic, with Neotropical species phylogenetically distinct from Asian species. This study of 29 accessions of 10 Neotropical taxa, and a total of 135 accessions representing 92 taxa of Homalomena, Furtadoa, and Philodendron for nuclear ITS and plastid matK regions, supports resurrection of the genus Adelonema for Neotropical species currently assigned to Homalomena. Adelonema is here delimited as a Neotropical genus of 16 species divided into two new sections: sect. Adelonema and sect. Curmeria, based on morphologically supported molecular results. The genus Adelonema is distinguished by a hypogeal rhizome, crushed vegetative tissues smelling of anise, an extensively sheathing, sometimes prickly petiole, chartaceous often variegated leaf blades, a spadix either obliquely inserted on the spathe/peduncle (sect. Adelonema), or stipitate (sect. Curmeria), ovaries with 2–4-pluriovulate locules, and anatropous ovules on an axile placenta. Four new species are described: Adelonema orientalis, A. palidinervia, A. panamensis, and A. yanamonoensis. Eleven new combinations are made: Adelonema allenii, A. crinipes, A. hammelii, A. kvistii, A. moffleriana, A. peltata, A. picturata, A. roezlii, A. speariae, A. wallisii, and A. wendlandii.

TAXONOMIC REVISION OF ANTHURIUM SECTION SEMAEOPHYLLIUM SCHOTT (ARACEAE)

ABSTRACT This study presents a complete taxonomic revision of Anthurium sect. Semaeophyllium, which comprises species with trilobed leaf blades. Leaf lobes are always united at the base in these species, and they can be directed forward (i.e., falcate) or to the sides (i.e., spreading) but never toward the back. Under this circumscription, sect. Semaeophyllium comprises 23 species ranging from southern Nicaragua into Peru. Detailed morphological descriptions, diagnoses, representative photographs, distribution maps, and an identification key are provided.

A reassessment of Anthurium species with palmately divided leaves, and a reinterpretation of Anthurium section Dactylophyllium (Araceae).

Abstract A reappraisal is made of the Anthurium Schott species with palmately divided leaves with 3 or more segments free to the base (i.e. palmatisect leaves), previously recognized as section Dactylophyllium Schott (Engler), as well as those species with 5 or more segments united at the base (i.e. palmatifid leaves), formerly placed in section Schizoplacium Schott (Engler). New molecular data indicates that several species (Anthurium pedatum (Kunth) Schott, Anthurium pedatoradiatum Schott, and possibly, Anthurium podophyllum (Schltdl. & Cham.) Kunth) should be excluded from section Schizoplacium, and other species previously placed in that section cannot be separated from section Dactylophyllium. Thus, Anthurium section Schizoplacium is here synonymized within section Dactylophyllium and type species are designated for both groups. This paper also provides an updated description of section Dactylophyllium as here emended, listing the 24 accepted taxa now included (20 species and 4 varieties or subspecies), along with their geographic distributions.

New species of Stenospermation and Xanthosoma (Araceae) from Bajo Calima, Valle Department, Colombia

ABSTRACT Eight new species of Stenospermation Schott and Xanthosoma Schott (Araceae) from Bajo Calima, Colombia, are described as new: Stenospermation ellipticum Croat & D. C. Bay, S. escobariae Croat & D. C. Bay, S. flavum Croat & D. C. Bay, S. glaucophyllum Croat & D. C. Bay, S. monsalvae Croat & D. C. Bay, S. velutinum Croat & D. C. Bay, Xanthosoma guttatum Croat & D. C. Bay, and X. hebetatum Croat & D. C. Bay.

Xanthosoma feuersteiniae (Araceae), a new species from southeastern Ecuador

Abstract Croat, T. B. & Bogner, J.: Xanthosoma feuersteiniae (Araceae), a new species from southeastern Ecuador. — Willdenowia 35: 327–331. — ISSN 0511-9618;

New species of Anthurium (Araceae) from the Cordillera del Cóndor, Ecuador

Abstract Croat T. B., Jackson A.† & Kostelac C. V.: New species of Anthurium (Araceae) from the Cordillera del Cóndor, Ecuador. — Willdenowia 40: 123–136. — Online ISSN 1868-6397;

Current status of aroid species diversity in Panama, including new records for the Country

ABSTRACT Araceae (aroids) is a large and ancient monocot plant family, most notable for its impressive morphological diversity and high life-form diversity which also represents a group with great economic importance, since many species are used as medicinal, edible and ornamental plants. The aroid flora of Central America has about 778 species in 26 genera (including three introduced genera). In Panama, several studies, mainly taxonomic (few floristic studies), have contributed to the knowledge of the aroid flora of the country. The latest Catalogue of the Vascular Plants of Panama list 349 published species of Araceae (355 species including Lemnoideae, formerly Lemnaceae). After this work, the number of species has increased significantly. In this paper, a brief historical review about the study of the Panamanian Araceae is made with comments on the current diversity of Panama. Additionally, five new records of Araceae for the country are presented.