Title Slide. I want to thank Dave Watson for inviting me to talk at this Symposium. It’s always a pleasure to speak to an audience that is already pre- selected as being interested in !

1 Slide. Studies of . The largest family of mistletoes is Loranthaceae. And as one might expect, it has been the subject of many scientific studies. This slide shows a variety of subdisciplines within biology that have focused on Loranthaceae, as well as a few areas that to date have not received any attention.

2 Slide. My talk today will focus upon the and evolutionary biology of Loranthaceae. As indicated in the title, I want to demonstrate how developing a meaningful taxonomy for a group is best accomplished using the most powerful tool in the systematist’s toolkit: molecular phylogenetics.

3 Slide. : The Largest Group of Parasitic . Among the twelve orders of flowering plants in which haustorial parasitism evolved, only two have more than three genera: Lamiales and Santalales. Of these, Lamiales contains a single family of hemi- and holoparasitic plants: Orobanchaceae with 93 genera (32%) and 1725 species (39%). Santalales is the largest order of parasitic plants, with 179 genera (61%) and 2407 species (54%). It’s the only order of parasitic with more than one family.

4 Slide. Within Santalales, Loranthaceae has by far the highest number of genera (75) with Balanophoraceae coming in second (17).

5 Slide. Loranthaceae also the highest number of species (987) with Viscaceae and Thesiaceae coming in second and third.

6 Slide. This slide has sorted the loranth genera according to size (number of species). Most genera are small, with 49 of the 75 with fewer than 10 species. The largest is Psittacanthus with 119 species, followed by Amyema with 92. It should be pointed out that none of these large genera have been subjected to molecular phylogenetic investigation. But in the talk following mine, Marcos Caraballo-Ortiz will present his phylogenetic study of Dendropemon.

7 Slide. Speaking of molecular phylogenetics, I would now like to orient everyone as to the existing knowledge on the phylogeny of Loranthaceae. This slide plots the occurrences of haustorial parasitism on the global angiosperm phylogeny. Among the 12 parasitism evolutionary events, one produced a clade we call Santalales – the sandalwoods. This order is now considered part of the “super-asterids”.

8 Slide. I am currently working on generating an overall phylogeny of Santalales. This seven gene matrix was assembled using mostly published Genbank sequences (most of which came from my lab) as well as some unpublished sequences. The genes are from the chloroplast and nuclear genomes totaling 13,995 characters. The matrix includes 147 genera of the 162 in the order, thus 15 genera are missing (mostly Loranthaceae). A total of 310 ingroup and 4 outgroup species were included. Of the seven genes used here, most have broad sampling and have been used to address intergeneric relationships. For closer (e.g. interspecific) relationships, 26S and trnLF have been used. Alignment of trnLF is problematic in some regions and future analyses will either work with a revised alignment or eliminate ambiguous regions. The matrix was ca. 25% filled. The seven individual genes were aligned by eye using SeAl and these matrices concatenated using Mesquite.

9 Slide. The majority rule consensus tree resulting from the Santalales 7-gene analysis is too large to show on one slide, but this cartoon summarizes the main results. There are many aspects of this tree I could discuss, but I show it mainly to indicate that the result we we reported in our 2010 paper in Taxon still holds. Loranthaceae is sister to a clade composed of Misodendraceae and Schoepfiaceae. Two of the five independent evolutions of aerial parasitism, mistletoes, is represented here.

10 Slide. This slide shows the Bayesian consensus tree reported in the AJB paper published by my doctoral student Romina Vidal-Russell and me in 2008. The tree shows that there are four major groups of loranths: the three root parasite genera with the plesiomorphic base chromosome number of 12, Tribe Elytranthinae (also with X = 12), Psittacanthinae (X = 8) and Loranthinae (X = 9).

11 Slide. This is a summary of our concept of the biogeography of Loranthaceae. The ancestral loranth existed on the supercontinent Gondwana ca. 80 mya (late Cretaceous). One ancestor, from west Gondwana, migrated into what is now southern South America. Some of these members underwent an aneuploid reduction to X = 8 (Tribe Psittacanthinae). Another ancestor, migrated into what is now Australia. Migration out of Australia to New Zealand, Malesia, southeast Asia and finally Africa involved first X=12 loranths but also mistletoes that underwent aneuploid reduction to X=11 and 9. Waves of reinvasion of Australia took place in two groups, tribe Elytrantheae and Subtribe Amyeminae. The X=9 group (Tribe Loranthinae) moved the farthest making it all the way to Africa where it underwent a massive adaptive radiation in conjunction with bird pollinators and seed dispersers. Bear in mind that this biogeographic scenario differs from that proposed by Barlow (1983, 1990) who had the African and Indian loranths in those regions as a result of the breakup of Gondwana. These events occurred too early for there to have been loranths on those supercontinental fragments, thus dispersal is a better explanation than vicariance.

12 Slide. Returning to the loranth phylogenetic tree. You can see that there is a lot of “karyological action” taking place in Tribe Psittacanthinae, with X = 8, 10, 12, and 16. Unresolved at the base of this clade is Tupeia from New Zealand, along with a relictual Andean taxon Desmaria. Further molecular work is needed to sort out these relationships which will provide important information crucial to our understanding of the early biogeographic history of the family.

13 Slide. This slide shows a current taxonomic classification for the X = 8 portion of Tribe Psittacantheae, namely subtribe Psittacanthinae. It consists of two groups: the large-flowered mistletoes in Psittacanthus and Aetanthus and the small-flowered group that contains 11 genera and is also called the Struthanthus complex. Notice that Job Kuijt has published taxonomic papers for most of these genera.

14 Slide. Anyone who looks at the taxonomic history of Loranthaceae would discover that the most of the work in this family since 1900 has been conducted by essentially five people. Bryan Barlow from Australia picked up where Benedictus Danser left off, covering Australia and Malesia. Roger Polhill and Delbert Wiens published the Mistletoes of Africa in 1998. And for the neotropical loranths, Job Kuijt has done the lion’s share of work. This photo of him was taken in 1957 when he worked at the University of California Jepson Herbarium. But because these workers had different taxonomic philosophies, genera are not equivalent in the Old and New World loranths. In other words, Barlow was a lumper and Kuijt a splitter. This is shown in molecular phylogenetic trees where branch lengths (genetic distance) is much shorter between genera of Psittacanthinae compared to genera in Old World tribes.

15 Slide. Job Kuijt’s most famous publication is of the book “Biology of Parasitic Flowering Plants” published in 1969. This book remains a central reference for all students of parasitic plants. Job is a classically trained morphologist who here is acknowledging the work on neotropical Loranthaceae by August Wilhelm Eichler.

16 Slide. As part of Job Kuijt’s revisionary work, a number of species have had complex nomenclatural histories. This volatility is such that generic boundaries are very plastic. This slide shows just two examples. Passovia stelis has been in the genus (as have most modern loranth genera), Phthirusa, and even Phoradendron! Peristethium leptostachyum has been in Struthanthus and Phthirusa.

17 Slide. Up until very recently, Kuijt has been reluctant to provide a list of characters that could be used to circumscribe the Struthanthus complex genera. No key was available that included all the genera. Very recently (2012) Kuijt published this table that shows the morphological features he considers diagnostic for the genera. Note that some of these genera share all of the same character states (or are included in the range), such as Maracanthus and Oryctina, Cladocolea and Peristethium, Phthirusa and Pusillanthus, and Dendropemon and Oryctanthus. It is also curious to see Maracanthus included in this table given that Kuijt sunk the genus into Oryctina in 1991 (has he forgotten?!). Tripodanthus is not included in the table. The column “monad bracteoles” is rather artificial and misleading. Those genera with triads also have bracteoles associated with their flowers. All of this taken together makes me question these generic circumscriptions.

18 Slide. Up until very recently, Kuijt has been reluctant to provide a list of characters that could be used to circumscribe the Struthanthus complex genera. No key was available that included all the genera. Very recently (2012) Kuijt published this table that shows the morphological features he considers diagnostic for the genera. Note that some of these genera share all of the same character states (or are included in the range), such as Maracanthus and Oryctina, Cladocolea and Peristethium, Phthirusa and Pusillanthus, and Dendropemon and Oryctanthus. It is also curious to see Maracanthus included in this table given that Kuijt sunk the genus into Oryctina in 1991 (has he forgotten?!). Tripodanthus is not included in the table. The column “monad bracteoles” is rather artificial and misleading. Those genera with triads also have bracteoles associated with their flowers. All of this taken together makes me question these generic circumscriptions.

21 Slide. Kuijt often focuses upon specific morphological features as having special importance. One such example is the Passovian anther. Here there are two kinds of stamens: long ones and short ones, where the anther sac of the short one fits into depressions formed in the filament of the long one. There may be an horn-like extension from the connective or not. And, the short stamen anther sacs may be sterile. These types of anthers are seen in Passovia, Dendropemon, Oryctanthus, and Oryctina. But how indicative of phylogenetic affinity is this character?

22 Slide. For the past year I have given several talks where I compare and contrast the concept of atavism with the more familiar (and widely used) terms convergence and parallelism. The main message I am sending is that for complex morphological features, it is likely that the structural genes underlying these features are not gained and lost through evolutionary time but are turned on and off, like a light switch, via activated or non-activated regulatory genes. This manifests as the sudden reappearance of a feature in one lineage where that feature was also seen in a distant ancestor. The example shown here is of a swollen pedicel seen as a synapomorphy (Exocarpos and Omphacomeria) and not (Anthobolus and Thesium). It is important to remember that one can only determine whether a feature is atavistic when you have a robust phylogenetic tree.

23 Slide. This figure shows a portion of the 7-gene tree, focused on Tribe Psittacantheae. Bear in mind this is a preliminary analysis so do not take the topological relationships too seriously. Three genera that show the Passovian anther occur in a clade at the red arrow along with Dendropemon with Oryctanthus. An unusual and possibly erroneous result is the position of the large-flowered genera are embedded within the small-flowered group. Also, Phthirusa (Ixocactus) inorna is not coming out with the other taxon previously placed in Phthirusa, Passovia pyrifolia. Is this evidence that Kuijt’s concept of splitting Phthirusa is correct? Or was the plant used to generate the sequences present on Genbank correctly identified? Note the convoluted nomenclatural history of this . What is called for is a formal molecular phylogenetic study that carefully documents (with vouchers) all taxa included in the study.

24 Slide. Brazilian to the rescue! Very recently Carlos Reif has begun pursuing a Ph.D. with Dr. Nina Rønsted at the Botanical Garden and Natural History Museum of Denmark. Carlos did a Masters degree at the Institute of Biological and Environmental Science at Santa Ursula University in Botafogo, Brazil. His thesis was titled (in English) “Contribution to the taxonomy of Eremolepidaceae, Loranthaceae and Viscaceae from Rio de Janeiro State, Brazil.” So Carlos just the type of “pre-adapted” student we need to tackle the taxonomy and phylogeny of the small-flowered neotropical loranths. He plans to work with Nina and me on various aspects of these fascinating mistletoes.

25 Slide. … and hopefully we can begin to sort out the main player in the Struthanthus complex – the genus Struthanthus itself.

26 Slide. The genus Psittacanthus, with beautiful red or orange flowers, was monographed by Job Kuijt recently (2009).

27 Slide. In that monograph, 119 species were recognized, 23 known only from the type, and 52 named for the first time. This genus presents a fantastic opportunity for a molecular phylogenetic study. If you are interested in doing this, please see me!

28 Slide. Kuijt (1981) provided a scheme whereby the various inflorescence types may have evolved in the genus. This scheme could be tested directly if we had a robust molecular phylogeny of the genus.

29 Slide. For more information on Parasitic Plants, visit the Parasitic Plant Connection web site that I created and have maintained for almost 20 years.

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