Reconsideration of the Phylogenetic Positions of Five Peritrich Genera,Vorticella, Pseudovorticella,Zoothamnopsis, Zoothamnium,and Epicarchesium (Ciliophora,Peritrichia, Sessilida), Based on Small Subunit rRNA Gene Sequences

ABSTRACT. In order to re‐evaluate the systematics of sessilid peritrich ciliates, small subunit (SSU) rRNA gene sequences were determined for 12 species belonging to five genera: Vorticella, Pseudovorticella, Epicarchesium, Zoothamnium, and Zoothamnopsis. Phylogenetic trees were deduced using Bayesian inference, maximum parsimony, and maximum likelihood methods. The phylogenetic analyses suggest that (1) sessilids which have stalks with continuous myonemes that contract in a zig‐zag fashion form a separate clade from those which have stalks that contract independently and in a spiral fashion, supporting the separation of the family Zoothamniidae from the family Vorticellidae and (2) Epicarchesium and Pseudovorticella, both of which have reticulate silverline systems, are more closely related to each other than to other vorticellids, suggesting that differences in the silverline system (i.e. transverse vs. reticulate) may be the result of genuine evolutionary divergence among sessilid peritrichs. However, the newly sequenced Zoothamnopsis sinica, which has a reticulate silverline pattern, nests within the unresolved Zoothamnium species that have transverse silverline patterns. Thus, there were at least two evolutions of the reticulate silverline pattern character state from a plesiomorphic transverse state in the peritrichid ciliates. The molecular work demonstrates the genus Zoothamnium to be paraphyletic in relation to morphological studies, and suggests that Astylozoon, Opisthonecta, and Vorticella microstoma possibly share a SSU rRNA secondary structure in the helix E10‐1 region.     

Genetic diversity and phylogenetic position of the subclass Astomatia (Ciliophora) based on a sampling of six genera from West African oligochaetes (Glossoscolecidae, Megascolecidae), including description of the new genus Paraclausilocola n. gen

To more confidently assess phylogenetic relationships among astome ciliates, we obtained small subunit (SSU) rRNA sequences from nine species distributed in six genera and three families: Almophrya bivacuolata, Eudrilophrya complanata, Metaracoelophrya sp. 1, Metaracoelophrya sp. 2, Metaracoelophrya intermedia, Metaradiophrya sp., Njinella prolifera, Paraclausilocola constricta n. gen., n. sp., and Paraclausilocola elongata n. sp. The two new species in the proposed new clausilocolid genus Paraclausilocola n. gen. are astomes with no attachment apparatus, two files of contractile vacuoles, and an arc-like anterior suture that has differentiations of thigmotactic ciliature on the anterior ends of the left kineties of the upper surface. Phylogenetic analyses were undertaken using neighbor-joining, Bayesian inference, maximum likelihood, and maximum parsimony. The nine species of astomes formed a strongly supported clade, showing the subclass Astomatia to be monophyletic and a weakly supported sister clade to the scuticociliates. There were two strongly supported clades within the astomes. However, genera assigned to the same family were found in different clades, and genera assigned to the same order were found in both clades. Thus, astome taxa appear to be paraphyletic when morphology is used to assign species to genera.     

Phylogenetic relationships of Pterocarya (Juglandaceae) with an emphasis on the taxonomic status of Iranian populations using ITS and trnH-psbA sequence data

Pterocarya fraxinifolia (Lam.) Spach., a relict tree species of the Juglandaceae family, is native to the Great Caucasus, Anatolia, and to the Hyrcanian forests of the southern Azerbaijan and Northern Iran. In this study, the phylogenetic relationship of the species, sampled in selected Iranian populations, and the global biogeography of the genus Pterocarya were addressed. Leaves were collected from 8 to 10 trees from three geographically isolated habitats. The samples were analyzed with nuclear (internal transcribed spacer [ITS] regions) and chloroplast (trnH-psbA) DNA markers. The obtained results were compared and analyzed with the data registered in NCBI GenBank. It is reported that the ITS regions varied from 644 to 652 for Pterocarya genus, but we did not observe polymorphisms for Iranian Pterocarya. The phylogenetic tree divided the Pterocarya genus in three clades: clade 1 grouping exclusively the samples P. fraxinifolia, clearly separated from the East Asiatic taxa; clade 2 that includes the species P. hupehensis and P. macroptera; clade 3 clustering P. stenoptera and P. tonkinensis. Although the Iranian Pterocarya samples and P. fraxinifolia from the Caucasus were in the same clade, they presented two different secondary structures. The Iranian populations showed the maximum genetic distance with P. stenoptera and P. tonkinensis. Our analysis demonstrates that the traditional division of all the six species sampled throughout their distribution area as well as the phylogeny of the genus Pterocarya needs to be reviewed.     

Molecular Phylogeny and Taxonomy of Two Novel Brackish Water Hypotrich Ciliates,with the Establishment of a New Genus,Antiokeronopsis gen. n. (Ciliophora,Hypotrichia)

Two novel brackish water urostyloid ciliates, Anteholosticha paramanca sp. n. and Antiokeronopsis flava gen. n., sp. n., isolated from the Shenzhen Mangrove Nature Protection Area on the coast of the South China Sea, were investigated using live observation and protargol impregnation techniques. Anteholosticha paramanca sp. n. is characterized by its spherical yellowish cortical granules arranged in lines, shortened midventral complex and three transverse cirri. Morphogenesis is similar to that in Anteholosticha manca. The new genus Antiokeronopsis is diagnosed by having a continuous adoral zone of membranelles, frontal cirri arranged in a bicorona, midventral complex composed of midventral pairs only, one marginal cirral row on each side, the presence of frontoterminal and transverse cirri, and the lack of buccal and caudal cirri. The type species A. flava sp. n. is characterized by its elongated body shape, brown to yellowish body color and two types of cortical granules. Small subunit ribosomal RNA gene sequence data justify the classification of both species. Phylogenetic analyses indicate that A. paramanca clusters with Bakuella subtropica within a clade that includes two other Anteholosticha species, while Antiokeronopsis groups within the core urostylids and is most closely related to the well‐known genera Pseudokeronopsis and Uroleptopsis.     

Molecular phylogeny of three ambiguous ciliate genera: Kentrophoros,Trachelolophos and Trachelotractus (Alveolata,Ciliophora)

Gao, S., Strüder‐Kypke, M.C., Al‐Rasheid, K.A.S., Lin, X. & Song, W. (2010). Molecular phylogeny of three ambiguous ciliate genera: Kentrophoros, Trachelolophos and Trachelotractus (Alveolata, Ciliophora).—Zoologica Scripta, 39, 305–313. Very few molecular studies on the phylogeny of the karyorelictean ciliates have been carried out because data of this highly ambiguous group are extremely scarce. In the present study, we sequenced the small subunit ribosomal RNA genes of three morphospecies representing two karyorelictean genera, Kentrophoros, Trachelolophos, and one haptorid, Trachelotractus, isolated from the South and East China Seas. The phylogenetic trees constructed using Bayesian inference, maximum likelihood, maximum parsimony and neighbor‐joining methods yielded essentially similar topologies. The class Karyorelictea is depicted as a monophyletic clade, closely related to the class Heterotrichea. The generic concept of the family Trachelocercidae is confirmed by the clustering of Trachelolophos and Tracheloraphis with high bootstrap support; nevertheless, the order Loxodida is paraphyletic. The transfer of the morphotype Trachelocerca entzi Kahl, 1927 to the class Litostomatea and into the new haptorid genus Trachelotractus, as suggested by previous researchers based on morphological studies, is consistently supported by our molecular analyses. In addition, the poorly known species Parduczia orbis occupies a well‐supported position basal to the Geleia clade, justifying the separation of these genera from one another.     

An ITS-based phylogenetic framework for the genus Vorticella: finding the molecular and morphological gaps in a taxonomically difficult group

Vorticella includes more than 100 currently recognized species and represents one of the most taxonomically challenging genera of ciliates. Molecular phylogenetic analysis of Vorticella has been performed so far with only sequences coding for small subunit ribosomal RNA (SSU rRNA); only a few of its species have been investigated using other genetic markers owing to a lack of similar sequences for comparison. Consequently, phylogenetic relationships within the genus remain unclear, and molecular discrimination between morphospecies is often difficult because most regions of the SSU rRNA gene are too highly conserved to be helpful. In this paper, we move molecular systematics for this group of ciliates to the infrageneric level by sequencing additional molecular markers—fast-evolving internal transcribed spacer (ITS) regions—in a broad sample of 66 individual samples of 28 morphospecies of Vorticella collected from Asia, North America and Europe. Our phylogenies all featured two strongly supported, highly divergent, paraphyletic clades (I, II) comprising the morphologically defined genus Vorticella. Three major lineages made up clade I, with a relatively well-resolved branching order in each one. The marked divergence of clade II from clade I confirms that the former should be recognized as a separate taxonomic unit as indicated by SSU rRNA phylogenies. We made the first attempt to elucidate relationships between species in clade II using both morphological and multi-gene approaches, and our data supported a close relationship between some morphospecies of Vorticella and Opisthonecta, indicating that relationships between species in the clade are far more complex than would be expected from their morphology. Different patterns of helix III of ITS2 secondary structure were clearly specific to clades and subclades of Vorticella and, therefore, may prove useful for resolving phylogenetic relationships in other groups of ciliates.     

Morphology and Phylogeny of Two Novel Ciliates,Arcanisutura chongmingensis n. gen., n. sp. and Naxella paralucida n. sp. from Shanghai,China

The morphologies of two novel ciliates, Arcanisutura chongmingensis n. gen., n. sp. and Naxella paralucida n. sp., collected from Shanghai, China, have been investigated using live observation and silver staining methods. Arcanisutura n. gen. can be easily distinguished from related genera by its inconspicuous, oblique anterior suture. Arcanisutura chongmingensis n. sp. is mainly recognized by its elongated body with a tail‐like posterior end, 25–33 somatic kineties, and 4–11 excretory pores. Naxella paralucida n. sp. can be distinguished from its congeners based on its two short nassulid organelles, fusiform trichocysts, 37–49 somatic kineties, and 16 nematodesmal rods. The small‐subunit (SSU) rRNA gene sequences of these two species are presented, revealing the phylogenetic positions of Arcanisutura and Naxella. Phylogenetic analyses show that Arcanisutura forms a sister clade to other synhymeniid genera, namely, Chilodontopsis, Orthodonella, and Zosterodasys; Naxella is most closely related to Nassula spp. and is located within the monophyletic clade of the family Nassulidae.     

Complete mitochondrial genome sequence and phylogenetic position of the Amu Darya sturgeon,Pseudoscaphirhynchus kaufmanni (Acipenseriformes: Acipenseridae)

In this study, we successfully assembled the complete mitochondrial genome of the Amu Darya sturgeon Pseudoscaphirhynchus kaufmanni. Based on this mitochondrial genome and previously published mitochondrial genomes of members of the Acipenseridae family, we assessed the phylogenetic position of P. kaufmanni using maximum likelihood and Bayesian inference for phylogeny reconstruction. The resultant phylogenetic trees were well-resolved, with congruence between different phylogenetic methods. This robust phylogenetic analysis elucidated the relationship among the four acipenserid genera and strongly supported the division of the family into three main clades. Evaluation of molecular phylogeny using maximum likelihood and Bayesian analysis led to the following conclusions: (a) the most basal position within the Acipenseridae remains in the clade containing Acipenser oxyrinchus and Acipenser sturio; (b) the genus Scaphirhynchus belongs to the Atlantic clade and is a sister group of the remaining species of the clade; and (c) the close relationship between P. kaufmanni and Acipenser stellatus is well supported.     

Phylogeny of the freshwater crabs of the Western Ghats (Brachyura,Gecarcinucidae)

The Western Ghats mountain range in India is a biodiversity hotspot for a variety of organisms including a large number of endemic freshwater crab species and genera of the family Gecarcinucidae. The phylogenetic relationships of these taxa, however, have remained poorly understood. Here, we present a phylogeny that includes 90% of peninsular Indian genera based on mitochondrial 16S rRNA and nuclear histone H3 gene sequences. The subfamily Gecarcinucinae was found to be paraphyletic with members of two other subfamilies, Liotelphusinae and Parathelphusinae, nesting within. We identify a well‐supported clade consisting of north Indian species and one clade comprising mostly south Indian species that inhabit the southern ‘sky islands’ of the Western Ghats. Relationships of early diverging genera, however, were resolved with low support. This study also includes newly sampled material from an isolated mountain plateau in the northern part of the Western Ghats, representing a new species of Gubernatoriana, which we describe here as Gubernatoriana basalticola sp. n. The new species is immediately distinguished from its congeners and the related genera Ghatiana and Inglethelphusa by its carapace and cheliped morphology, which are unique among Indian freshwater crabs. This study highlights the urgent need for continued faunistic studies to assess the true diversity of gecarcinucid crabs on the Indian subcontinent, to fully understand the basal phylogenetic relationships within the freshwater crab family Gecarcinucidae, and to evaluate the conservation threat status and biogeography of the montane freshwater crabs of the Western Ghats.     

Plastome phylogeny and lineage diversification of Salicaceae with focus on poplars and willows

Phylogenetic relationships and lineage diversification of the family Salicaceae sensu lato (s.l.) remain poorly understood. In this study, we examined phylogenetic relationships between 42 species from six genera based on the complete plastomes. Phylogenetic analyses of 77 protein coding genes of the plastomes produced good resolution of the interrelationships among most sampled species and the recovered clades. Of the sampled genera from the family, Flacourtia was identified as the most basal and the successive clades comprised both Itoa and Poliothyrsis, Idesia, two genera of the Salicaceae sensu stricto (s.s.) (Populus and Salix). Five major subclades were recovered within the Populus clade. These subclades and their interrelationships are largely inconsistent with morphological classifications and molecular phylogeny based on nuclear internal transcribed spacer sequence variations. Two major subclades were identified for the Salix clade. Molecular dating suggested that species diversification of the major subclades in the Populus and Salix clades occurred mainly within the recent Pliocene. In addition, we found that the rpl32 gene was lost and the rps7 gene evolved into a pseudogene multiple times in the sampled genera of the Salicaceae s.l. Compared with previous studies, our results provide a well‐resolved phylogeny from the perspective of the plastomes.     

57 Systematics of hydropuntia montagne (gracilariaceae,gracilariales, rhodophyta) based on comparative morphology and rbcL sequence analysis

The taxonomic validity of the genus Hydropuntia Montagne (1843) (including Polycavernosa) within the Gracilariaceae (Gracilariales, Rhodophyta) is controversial. Morphological characters that define species of Hydropuntia are said to be variable and to overlap with those of Gracilaria. Here we present a global phylogenetic study of the family based on a Bayesian analysis of a large rbcL DNA sequence dataset indicating that the genus Hydropuntia forms a well supported monophyletic clade within the family, and recognize Hydropuntia as a genus distinct from Gracilaria. We also conducted smaller phylogenetic analyses in which thirty four Hydropuntia rbcL sequences resulted in two major clades within the genus, comprising a Caribbean clade and an Indo‐Pacific clade. Diagnostic reproductive stages that separate these two clades will be illustrated.     

Phylogenetic relationships of leptophlebiid mayflies as inferred by histone H3 and 28S ribosomal DNA

Abstract Leptophlebiidae is among the largest and most diverse groups of extant mayflies (Ephemeroptera), but little is known of family‐level phylogenetic relationships. Using two nuclear genes (the D2 + D3 region of 28S ribosomal DNA and histone H3) and maximum parsimony (MP), maximum likelihood (ML) and Bayesian inference (BI), we inferred the evolutionary relationships of 69 leptophlebiids sampled from six continents and representing 30 genera plus 11 taxa of uncertain taxonomic rank from Madagascar and Papua New Guinea. Although we did not recover monophyly of the Leptophlebiidae, monophyly of two of the three leptophlebiid subfamilies, Habrophlebiinae and Leptophlebiinae, was recovered with moderate to strong support in most analyses. The Atalophlebiinae was rendered paraphyletic as a result of the inclusion of members of Ephemerellidae or the Leptophlebiinae clade. For the species‐rich Atalophlebiinae, four groups of taxa were recovered with moderate to strong branch support: (i) an endemic Malagasy clade, (ii) a Paleoaustral group, a pan‐continental cluster with members drawn from across the southern hemisphere, (iii) a group, uniting fauna from North America, southeast Asia and Madagascar, which we call the Choroterpes group and (iv) a group uniting three New World genera, Thraulodes, Farrodes and Traverella. Knowledge of the phylogenetic relationships of the leptophlebiids will aid in future studies of morphological evolution and biogeographical patterns in this highly diverse and speciose family of mayflies.     

A phylogenetic reconsideration of suctorian ciliates (Protista,Ciliophora, Phyllopharyngea) based on small subunit rRNA gene sequences

Compared with other ciliated protozoa, molecular studies of phylogenetic relationships within the subclass Suctoria are rare. In this work, phylogenetic analyses focusing on this group were performed based on all data available. In addition, the small subunit ribosomal RNA (SSU rRNA) genes of three suctorian ciliates (Acineta compressa, Acineta tuberosa and Paracineta limbata) were newly sequenced. Furthermore, the putative secondary structures of the variable region 2 of the SSU rRNA gene were predicted and compared within the Suctoria. Our results show that (i) there is support for the monophyly of the subclass Suctoria, which is a sister clade to the cyrtophorids; (ii) based on combined morphologic and molecular features, we propose the following evolutionary routine within the Suctoria: Exogenina – Evaginogenina – Endogenina; (iii) the similarities of the secondary structures of the V2 region and the SSU rRNA gene sequences within the subclass Suctoria are consistent with the branching of the phylogenetic lineages.     

Diversity and endemism of ciliates inhabiting Neotropical phytotelmata

While the diversity and distribution of macro-organisms living in phytotelmata (plant-container habitats) is well known, detailed taxonomic work on micro-organisms living in the same environments is limited. As a model clade of microbial eukaryotes, sampling of ciliates in Neotropical bromeliad tanks increased, and Neotropical phytotelmata such as bamboo stumps and tree holes were newly sampled. Thirty-three isolates from Brazil, Costa Rica, Dominican Republic, Jamaica and Mexico were sequenced for small subunit rDNA, and placed into a phylogenetic context using non-phytotelmata GenBank accessions. This and the morphological investigations discovered 45 undescribed, possibly endemic ciliate species. The potential endemics are from throughout most clades of the ciliate tree of life, and there is evidence of speciation within the Neotropical phytotelmata habitat. Our data show the number of potential Neotropical phytotelmata-endemic ciliate species increasing as more phytotelmata are sampled. While the new data show that the supposed endemics are mainly recruited from moss and ephemeral limnetic habitats, the bromeliad ciliate fauna is quite distinct from those of other limnetic habitats, lacking many typical and common freshwater genera, such as Coleps, Colpidium, Frontonia, Paramecium, Glaucoma, Nassula, Stylonychia and Trithigmostoma. There is no indication that specific ciliates are confined to specific bromeliads.     

Phylogenetic positions of seven poorly known species of Ferula (Apiaceae) with remarks on the phylogenetic utility of the plastid trnH-psbA,trnS-trnG,and atpB-rbcL intergenic spacers

Ferula L. is one of the most species-rich and taxonomically difficult genera of Apiaceae. In this study, we obtained nrDNA ITS sequences of seven poorly known species of Ferula (Ferula anatolica, Ferula sp. (tentatively identified as F. candelabrum by collectors), F. drudeana, F. huber-morathii, F. marmarica, F. talassica, and F. tunetana) and explored their phylogenetic positions using 148 ITS sequences of the subtribe Ferulinae from GenBank. Five of these newly sequenced species fall into three groups, corresponding to clades recognized in earlier molecular studies. Ferula sp. are added to clade, which is mostly composed of Central Asian species. This placement showed that identification as F. candelabrum was erroneous. The second clade, which is mostly composed of Mediterranean taxa, includes two species from North Africa: F. marmarica and F. tunetana. Despite the well-supported monophyly of this clade, the relationships inside this group need to be revised, as broadly distributed F. communis is paraphyletic with respect to other species. Ferula drudeana and F. huber-morathii, two narrow endemics from Turkey, are placed in the Central Asian clade. Two species, F. anatolica and F. talassica, do not fall into any of the recognized clades. In addition, we examined the sequence variation of three potentially highly variable pDNA regions, the trnH-psbA, trnS-trnG, and atpB-rbcL intergenic spacers, for a subset of 18 specimens. The resulting pDNA and ITS based phylogenetic trees were incongruent, as supported by significant ILD tests. The cause of this incongruence can be manifold, including hybridization, a lack of a phylogenetic signal, and homoplastic substitutions. Our analyses suggest that only trnS-trnG can be added to the list of pDNA markers used for phylogenetic studies of Ferula, as it has the highest number of parsimony informative characters and is easy to amplify from degraded material.     

The phylogenetic systematics of blue‐tailed skinks (Plestiodon) and the family Scincidae

Blue‐tailed skinks (genus Plestiodon) are a common component of the terrestrial herpetofauna throughout their range in eastern Eurasia and North and Middle America. Plestiodon species are also frequent subjects of ecological and evolutionary research, yet a comprehensive, well‐supported phylogenetic framework does not yet exist for this genus. We construct a comprehensive molecular phylogeny of Plestiodon using Bayesian phylogenetic analyses of a nine‐locus data set comprising 8308 base pairs of DNA, sampled from 38 of the 43 species in the genus. We evaluate potential gene tree/species tree discordance by conducting phylogenetic analyses of the concatenated and individual locus data sets, as well as employing coalescent‐based methods. Specifically, we address the placement of Plestiodon within the evolutionary tree of Scincidae, as well as the phylogenetic relationships between Plestiodon species, and their taxonomy. Given our sampling of major Scincidae lineages, we also re‐evaluate ‘deep’ relationships within the family, with the goal of resolving relationships that have been ambiguous in recent molecular phylogenetic analyses. We infer strong support for several scincid relationships, including a major clade of ‘scincines’ and the inter‐relationships of major Mediterranean and southern African genera. Although we could not estimate the precise phylogenetic affinities of Plestiodon with statistically significant support, we nonetheless infer significant support for its inclusion in a large ‘scincine’ clade exclusive of Acontinae, Lygosominae, Brachymeles, and Ophiomorus. Plestiodon comprises three major geographically cohesive clades. One of these clades is composed of mostly large‐bodied species inhabiting northern Indochina, south‐eastern China (including Taiwan), and the southern Ryukyu Islands of Japan. The second clade comprises species inhabiting central China (including Taiwan) and the entire Japanese archipelago. The third clade exclusively inhabits North and Middle America and the island of Bermuda. A vast majority of interspecific relationships are strongly supported in the concatenated data analysis, but there is nonetheless significant conflict amongst the individual gene trees. Coalescent‐based gene tree/species tree analyses indicate that incongruence amongst the nuclear loci may severely obscure the phylogenetic inter‐relationships of the primarily small‐bodied Plestiodon species that inhabit the central Mexican highlands. These same analyses do support the sister relationship between Plestiodon marginatus Hallowell, 1861 and Plestiodon stimpsonii (Thompson, 1912), and differ with the mitochondrial DNA analysis that supports Plestiodon elegans (Boulenger, 1887) + P. stimpsonii. Finally, because the existing Plestiodon taxonomy is a poor representation of evolutionary relationships, we replace the existing supraspecific taxonomy with one congruent with our phylogenetic results. © 2012 The Linnean Society of London, Zoological Journal of the Linnean Society, 2012, 165 , 163–189.     

Multilocus phylogeny of a cryptic radiation of Afrotropical long-fingered bats (Chiroptera,Miniopteridae)

The Old World bat family Miniopteridae comprises only the genus Miniopterus, which includes 20 currently recognized species from the Afrotropical realm and 15 species from Eurasia and Australasia. Since 2003, the number of recognized Miniopterus species has grown from 19 to 35, with most newly described species endemic to Madagascar and the Comoros Archipelago. We investigated genetic variation, phylogenetic relationships and clade membership in Miniopterus focusing on Afrotropical taxa. We generated mitochondrial cytochrome-b (cyt-b) and nuclear intron data (five genes) from 352 vouchered individuals collected at 78 georeferenced localities. Including 99 additional mitochondrial sequences from GenBank, we analysed a total of 25 recognized species. Mitochondrial genetic distances among cyt-b-supported clades averaged 9.3%, representing as many as five undescribed species. Multilocus coalescent delimitation strongly supported the genetic isolation of eight of nine tested unnamed clades. A large number of sampled clades in sub-Saharan Africa are distributed wholly or partly in East Africa (nine of 13 clades), suggesting that Miniopterus diversity has been grossly underestimated. Although 25 of 27 cyt-b and 23 of 25 nuclear gene tree lineages from the Afrotropics were strongly supported as monophyletic, a majority of deep nodes were poorly resolved in phylogenetic analyses. Long terminal branches subtending short backbone internodes in the phylogenetic analyses suggest a rapid radiation model of diversification. This hypothesis needs to be tested using more phylogenetically informative data.