John L. Clark

Phylogenetic relationships and generic boundaries in the Episcieae (Gesneriaceae) inferred from nuclear, chloroplast, and morphological data

Episcieae is the most diverse tribe of Gesneriaceae, with 22 genera and over 700 species, or roughly 21% of all Gesneriaceae. The tribe is restricted to the Neotropics and is characterized by axillary flowers derived from a pair-flowered cyme inflorescence by reduction, a three-trace trilacunar node with split lateral bundles, superior ovaries, and with most members having a haploid chromosome number of n = 9 [n = 8 in Codonanthe and Nematanthus]. Most traditionally recognized genera in Episcieae are either known to be non-monophyletic or have not been represented adequately in phylogenetic analyses to test their monophyly. This paper presents phylogenetic analyses utilizing two molecular [the internal transcribed spacer region of 18S-26S nuclear ribosomal DNA (ITS) and the trnH-psbA intergenic spacer for 155 species] and one morphological (99 characters for 120 species) datasets, combined in a total evidence analysis. All traditionally recognized genera of Episcieae except for the monotypic genus Lampadaria are represented. Of the 21 sampled genera in Episcieae, 16 are represented by the generic type species. The genera Glossoloma and Crantzia are segregated from the genus Alloplectus as traditionally recognized. Other genera that are strongly supported as monophyletic include Alsobia, Columnea (with the inclusion of C. dielsii), Corytoplectus, and Episcia. Drymonia is weakly supported and is shown here to be morphologically diverse and in need of further evaluation. Evolution of fruit structure is examined in the context of the phylogenetic results presented here with two previously unreported features that are here referred to as capsules with tardily dehiscent and non-dehiscent endocarps. Three independent origins of resupinate flowers are inferred for Glossoloma, Nematanthus, and Crantzia. Strongly supported clades have centers of diversity in southeastern Brazil (Nematanthus, Codonanthe, Codonanthopsis, and Paradrymonia anisophylla), northern South America (Alloplectus, Drymonia, Columnea, Neomortonia), Central America (Alsobia, Oerstedina, Rufodorsia, Cobananthus), and two clades with diversity in the Guiana Shield [(Paradrymonia, Nautilocalyx, Chrysothemis) and (Lembocarpus, Cremersia, Rhoogeton)]. Neomortonia, a genus of three species, is poorly supported due to conflict among datasets.

Phylogeny of a Neotropical Clade in the Gesneriaceae: More Tales of Convergent Evolution

The Gesneriaceae is a family known for convergent evolution of complex floral forms. As a result, defining genera and resolving evolutionary relationships among such genera using morphological data alone has been challenging and often does not accurately reflect monophyletic lineages. The tribe Episcieae is the most diverse within Neotropical Gesneriaceae in terms of its number of species and morphological diversity. As a result, defining genera using floral characters has been historically troublesome. Here we investigate relationships among genera of the tribe using an array of chloroplast DNA, nuclear ribosomal genes, and low-copy nuclear genes to provide resolution for the monophyly of the genera and relationships among the monophyletic groups. All known genera in the tribe (with the exception of the monospecific Lampadaria) have been sampled, and most have been sampled to provide an assessment to determine their monophyly. Of the 17 genera in the tribe that comprise more than a single species, we have sampled 15 with at least two species. The following six genera are identified as para- or polyphyletic: Neomortonia, Episcia, Paradrymonia, Nautilocalyx, Codonanthe, and Nematanthus. Our results strongly support at least three independent origins of fleshy fruits, which are defined here as fleshy display capsules or indehiscent berries.

Shuaria (Gesneriaceae), an arborescent new genus from the Cordillera del Cóndor and Amazonian Ecuador.

Abstract A new neotropical genus, Shuaria, with a single species, S. ecuadorica, is described from the Cordillera del Cóndor and Amazonian regions of southeastern Ecuador and is placed in the family Gesneriaceae, tribe Beslerieae. The placement of Shuaria in the tribe Beslerieae is strongly supported by molecular sequence data generated from analyses of nuclear ribosomal DNA internal transcribed spacer region (ITS), and the chloroplast DNA trnL intron, trnL-trnF intergenic spacer region. Sequence data were generated for 33 species representing most of the generic diversity from the tribes Beslerieae and Napeantheae. Shuaria is characterized by the following unique combination of relatively uncommon characters in the Gesneriaceae: arborescent habit; opposite leaf arrangement sometimes interrupted by alternate leaves; lepidote trichomes on vegetative and floral structures; small white flowers with a dorsal gibbosity at the base of the corolla tube; and a bivalved septicidally dehiscent capsule. The suite of uncommon characters initially made Shuaria difficult to place in the Gesneriaceae and within a known tribe. Shuaria is restricted to the Ecuadorian provinces of Pastaza, Morona-Santiago, and Zamora-Chinchipe in lowland Amazonian tropical wet forest and in lower montane cloud forest on the western slopes of the Cordillera del Cóndor. A key and a table are presented for differentiating Shuaria from other related genera.

Independent Origin of Radial Floral Symmetry in the Gloxinieae (Gesnerioideae: Gesneriaceae) is Supported by the Rediscovery of Phinaea pulchella in Cuba

Abstract Phinaea, in the currently accepted circumscription, is a genus in the flowering plant family Gesneriaceae with three widely disjunct species. These species are known from small populations in Mexico, northern South America, and the West Indies (Cuba and Haiti), respectively. Phinaea pulchella is one of the few members of the tribe Gloxinieae that occurs naturally in the West Indies and it is the only member of the tribe endemic to that region. It was rediscovered in Cuba in 2008, more than fifty years after it was last documented. Results from molecular data generated from the nrDNA ITS and cpDNA trnL-F regions strongly support that P. pulchella does not group with other Phinaea species and instead shares a recent common ancestor with Diastema vexans in a clade that is sister to Pearcea and Kohleria. The phylogenetic placement of P. pulchella suggests that radial floral symmetry and buzz-pollination is autapmorphic in this taxon. Our results strongly support convergence of radial symmetry and associated characters with buzz-pollination in the following taxa in the tribe Gloxinieae: Niphaea, Phinaea s. s., Phinaea pulchella, and Amalophyllon. New generic circumscriptions based on the results presented here are not suggested until more complete taxon sampling includes additional species currently recognized in Amalophyllon.

Grias longirachis (Lecythidaceae), a new species from northwestern Ecuador.

A new species,Grias longirachis S. A. Mori & J. L. Clark, with enclosed calyx in bud and unusually long inflorescence rachises, is described based on collections from northwestern Ecuador. A key to the species ofGrias is provided.

Paraphyly of Section Stygnanthe (Columnea, Gesneriaceae) and a Revision of the Species of Section Angustiflorae, a New Section Inferred from ITS and Chloroplast DNA Data

Abstract Morphological data have produced conflicting results when analyzing evolutionary relationships within Gesneriaceae due to convergence of morphological characters. Columnea, the largest Neotropical genus in Gesneriaceae subfamily Gesnerioideae, has had a convoluted taxonomic history due to this convergence. Previously, the 200 + species of Columnea were placed in 14 genera, with up to nine sections in the genus; most recently classifying the species in a single genus with five sections. Phylogenetic analyses presented here included 129 accessions representing 90 species for five chloroplast gene regions (trnQ-rps16 spacer, rpl32-trnLUAG spacer, rps16 intron, trnS-G spacer, and trnH-psbA spacer) and nuclear ribosomal ITS to build a well-supported topology that can test the previously proposed subgeneric classifications. Our goal was to test the monophyly of section Stygnanthe, one of the five sections that encompasses 18 species based on floral morphology. Fifteen species of Stygnanthe and four species that had not been classified in Stygnanthe but shared similar floral morphologies were included in the molecular phylogenetic analyses. Analyses indicate that the 19 species with a similar floral morphology belong in four separate clades including a newly proposed section, Columnea section Angustiflorae. Of the remaining three species with similar morphologies that were not sampled, only one is proposed to be a member of section Angustiflorae, none are members of clade Stygnanthe, but are likely to belong in other clades.

Molecular Phylogenetic Analyses Reveal Undiscovered Monospecific Genera in the tribe Episcieae (Gesneriaceae)

Abstract Recent molecular phylogenetic analyses have revealed that many genera in tribe Episcieae of Gesneriaceae are polyphyletic. The strong support from molecular data necessitates name changes for these taxa. In this paper we make the formal transfer of these species. As a result, four monospecific new genera are described to accommodate monophyletic lineages. The option to create monospecific genera is made as opposed to including these species in single, large, morphologically heterogeneous genera. The new genera are Christopheria, Lesia, Pachycaulos , and Pagothyra , and include the species Christopheria xantha, Lesia savannarum, Pachycaulos nummularium , and Pagothyra maculata .

Molecular Phylogeny of the Neotropical Genus Paradrymonia(Gesneriaceae), Reexamination of Generic Concepts and the Resurrection of Trichodrymonia and Centrosolenia

Abstract Paradrymonia Hanst. (Gesneriaceae) with 40 currently recognized species is a genus of facultative epiphytic herbs that inhabits the forest understory. The genus occurs throughout the Neotropics except for southeastern Brazil and the Caribbean. Monophyly of neotropical Paradrymonia and species relationships within the genus and closely related genera were evaluated based on molecular sequence data from the nuclear ribosomal (nrDNA) internal and external transcribed spacer regions (ITS and ETS), and the plastid (cpDNA) psbA-trnH intergenic spacer. Traditional Paradrymonia is resolved as polyphyletic and includes taxa in three clades. The clade that contains the type species is recognized as Paradrymonia sensu stricto (s. s.) and includes three species. The Paradrymonia s. s. clade is sister to a clade that includes species of Nautilocalyx, Chrysothemis, and most of the species traditionally recognized as Paradrymonia. Morphological characters useful for circumscribing generic boundaries include bearded anthers, rosette habit, presence of leaf anisophylly, and lanceolate calyx lobe shape. Our results support the re-circumscription of Paradrymonia and the resurrection of two previously recognized genera, Centrosolenia and Trichodrymonia, in order to accommodate the remaining ex-Paradrymonia species. Forty-three new combinations (11 in Centrosolenia, four in Chrysothemis, and 28 in Trichodrymonia) are made. The genus Nautilocalyx is moderately supported as lacking monophyly, but broader taxon sampling is necessary before new generic circumscriptions are provided.

Novae Gesneriaceae Neotropicarum XVII: New Combinations and Typifications

Abstract.  Fieldwork and current research projects in Central and South America on the Gesneriaceae have shown that nomenclatural and taxonomic changes are needed. The Ecuadorian endemic species Columnea albovinosa (M. Freiberg) J. L. Clark & L. E. Skog is transferred from Dalbergaria Tussac. The name Pentadenia lutea M. Freiberg is synonymized with C. angustata (Wiehler) L. E. Skog. Amalophyllon ecuadoranum (Wiehler) J. L. Clark, comb. nov., is recognized as a species distinct from A. divaricatum (Poepp.) Boggan, L. E. Skog & Roalson. The application of the name C. serrata (Klotzsch ex Oerst.) Hanst. is stabilized by the designation of a neotype. The new name Drymonia ovatifolia J. L. Clark is made for the species Nautilocalyx dressleri Wiehler. Resia bracteata, a name originally published without a Latin diagnosis, is here validly published as R. bracteata J. L. Clark & L. E. Skog. Resumen.  El trabajo de campo en Gesneriaceae realizado en Centro y Sur América, ha evidenciado la necesidad de realizar algunos cambios taxonómicos y nomenclaturales. Columnea albovinosa (M. Freiberg) J. L. Clark & L. E. Skog, especie endémica de Ecuador, se transfiere de Dalbergaria Tussac. Pentadenia lutea M. Freiberg es sinonimizada con C. angustata (Wiehler) L. E. Skog. Se reconoce a Amalophyllon ecuadoranum (Wiehler) J. L. Clark, comb. nov., como una especie diferente de A. divaricatum (Poepp.) Boggan, L. E. Skog & Roalson. Para preservar la estabilidad de la especie se designa un neotipo para C. serrata (Klotzsch ex Oerst.) Hanst. Se crea un nuevo nombre, Drymonia ovatifolia J. L. Clark, para la especie Nautilocalyx dressleri Wiehler. La especie Resia bracteata, originalmente publicada sin la diagnosis en latín, es válidamente publicada como R. bracteata J. L. Clark & L. E. Skog.

Novae Gesneriaceae Neotropicarum VIII: Alloplectus grandicalyx, a new species from Colombia and Ecuador

A new species, Alloplectus grandicalyx J. L. Clark & L. E. Skog, is described from northern Ecuador and southern Colombia. Alloplectus grandicalyx is differentiated from other similar species on the basis of larger calyx lobes, longer pedicels, and villous pubescence on the stems, leaves, petioles, and calyx lobes. A key is provided to help distinguish A. grandicalyx from other shrubby and resupinate flowered Alloplectus species. In addition, the commonly confused and widely spread Alloplectus tetragonoides Mansfeld is discussed and neotypified.