What’s new in the Porter Lab…

Two new species of Loeselia (Polemoniaceae) from central Mexico are being described and illustrated in Systematic Botany vol. 34.  Both are known only from small areas in the Balsas Depression of the state of Michoacán.  Loeselia tancitaroensis occurs in pine-oak forest on the foothills of Cerro Tancítaro.  It is similar to the Oaxacan endemic L. ruprestis, from which it differs in possessing linear to linear-lanceolate inflorescence bracts, entire to rarely one-toothed floral bracts and sepals, shorter sepals and ovaries, and carpels with two ovules each.  Loeselia spectabilis is restricted to tropical deciduous forest in the Infiernillo region.  It is distinguished from the closely related L. grandiflora by possessing petiolate leaves, shorter sepals, glandular-ciliate corolla margins, and carpels with a single ovule.

The genus Ipomopsis (Polemoniaceae) encompasses about 29 species and 24 subspecies generally divided into three sections: sect. Ipomopsis, sect. Microgilia, and sect. Phloganthea. Leigh Johnson, Dieter Wilken, and I employed maximum likelihood and Bayesian inference of DNA sequences from the nuclear ribosomal ITS region (ITS1, 5.8S ribosomal subunit, ITS2) and the chloroplast trnL–F region (trnL intron + trnL–trnF intergenic spacer) to estimate phylogenetic relationships within this genus and its placement among other genera of Polemoniaceae. Results from this research are being published in Systematic Botany vol. 34. One of the major outcomes of this study is that we find support for the monophyly of Ipomopsis, but only if four species previously included in the genus are removed: Ipomopsis havardii, I. sonorae, Microgilia minutiflora ( = I. minutiflora), and Loeseliastrum depressum ( = I. depressa). Of the three sections previously recognized, two are conditionally supported as monophyletic. Section Microgilia (with 11 species and 11 infra-specific taxa) is supported as monophyletic if I. polycladon, I. sonorae, I. depressa, and I. minutiflora (the type of the section) are removed. This clade will be treated as section Elaphocera. Section Ipomopsis is inferred to be monophyletic with the inclusion of several members of sect. Phloganthea (I. multiflora, I. pinnata, and I. polyantha). The Giliopsis group (I. effusa, I. guttata, and I. tenuifolia) is supported as monophyletic by both data sets, and the cp sequences place it as sister to the remainder of Ipomopsis. This clade will be treated as the new section, Giliopsis. By contrast, there is no support for monophyly or paraphyly of sect. Phloganthea. Using the Eocene fossil Gilisenium hueberii to calibrate the most recent common ancestor of tribe Gilieae, we estimate that Ipomopsis has its origin 28.2 ± 0. 40 to 39.0 ± 1.14 MYA (trnL–F and ITS, respectively). Using this same relaxed clock, the node (or coalescent event) that defines the I. aggregata complex is dated at 16.2 ± 0.38 and 27.1 ± 0.83 MYA (trnL–F and ITS, respectively).



Loeselia tancitaroensis

Loeselia spectabilis

Ipomopsis: Floral form and variation in Ipomopsis: Section Giliopsis, (Section Phloganthea sensu V. Grant, in part; A–C)—A. Ipomopsis effusa (A. Gray) Moran, B. I. tenuifolia (A. Gray) V.E. Grant, C. I. guttata (A. Gray) Moran; D. Ipomopsis havardii (A. Gray) V.E. Grant (Section Phloganthea sensu V. Grant); Section Ipomopsis (E–H)—E. I. aggregata (Pursh.) V.E. Grant subsp. aggregata, F. I. tenuituba (Rydb.) V.E. Grant subsp. tenuituba, G. I. thurberi (Torr. ex A. Gray) V.E. Grant, H. Gilia polyantha Rydb. var. whitingii Kearney & Peebles (Section Phloganthea sensu V. Grant); section Elaphocera (sect. Microgilia sensu V. Grant)—I. I. congesta (Hook.) V.E. Grant subsp. palmifrons (Brand) A.G. Day, J. I. congesta (Hook.) V.E. Grant subsp. nevadensis (Tidestr.) Kartez & Gandhi, K. I. gunnisonii (Torr. & A. Gray) V.E. Grant, L. I. roseata (Rydb.) V.E. Grant. Scale bars for A–H= 5.0 mm, I–L= 2.0 mm.

DNA sequences

monophyly: Phylogenetic relationships of Ipomopsis, in the context of members of Polemoniaceae Tribe Loeselieae (Porter and Johnson 2000), inferred from maximum likelihood analysis (ML). The single ML (-lnL= 17862.76502) tree, based on comparative DNA sequences of combined chloroplast trnL intron and trnL-F intergenic spacer regions and nuclear ribosomal internal transcribed spacer regions (ITS1, 5.8S, ITS2). Bayesian posterior probabilities are adjacent to the corresponding branches. The small boxes adjacent to species names reflect the placement of species in Grant’s (1956, 1959) sectional classification of Ipomopsis: red= Section Ipomopsis, blue= Section Phloganthea, green= Section Microgilia. Clades corresponding to classification based on monophyly are indicated by colored boxes: yellow= Ipomopsis (genus), pink= Section Ipomopsis, green= Section Elaphocera, blue= Section Giliopsis.

calibrate: Chronogram of Polemoniaceae, based upon maximum likelihood (ML) analysis of combined chloroplast trnL intron and trnL-F intergenic spacer regions and nuclear ribosomal internal transcribed spacer regions (ITS1, 5.8S, ITS2). ML branch lengths were rescaled using nonparametric rate smoothing (Sanderson 1997). The tree was calibrated at the node indicated with an asterisk, using the fossil Gilisenium hueberii. Clades A–E indicate the target clades for dating using a sample from the posterior distributions of trees from trnL-F region, ITS region and combined data Bayesian analyses. Epochs of the geological time scale are indicated; however, the Pleistocene (yellow) and Holocene (white) are not labeled.