Hartmut H. Hilger

A systematic analysis of Heliotropium, Tournefortia, and allied taxa of the Heliotropiaceae (Boraginales) based on ITS1 sequences and morphological data

The relationships of Heliotropium, Tournefortia, Schleidenia, Ixorhea, and Ceballosia of the Heliotropiaceae (Boraginaceae in the traditional sense, Boraginales) are investigated using molecular data (ITS1). These genera form a monophyletic group. Five clades can be distinguished on the basis of molecular data, morphological traits, and distribution. In their current circumscription, Tournefortia is polyphyletic and Heliotropium is paraphyletic. Tournefortia section Cyphocyema is the sister group to all other ingroup taxa. Heliotropium section Orthostachys including Schleidenia sensu lato is the well supported sister group of a clade comprising the other species of Heliotropium sensu stricto (s.s.), Tournefortia section Tournefortia, and Ceballosia. Heliotropium s.s. forms two clades: one clade includes all species of the Old World and represents the only monophylum of Heliotropium s.s. The other clade consists of all Heliotropium s.s. species of the New World but also includes Tournefortia section Tournefortia and Ceballosia. The results suggest that taxonomic changes are inevitable.

Diversification in the Andes: age and origins of South American Heliotropium lineages (Heliotropiaceae, Boraginales).

The uplift of the Andes was a major factor for plant diversification in South America and had significant effects on the climatic patterns at the continental scale. It was crucial for the formation of the arid environments in south-eastern and western South America. However, both the timing of the major stages of the Andean uplift and the onset of aridity in western South America remain controversial. In this paper we examine the hypothesis that the Andean South American groups of Heliotropium originated and diversified in response to Andean orogeny during the late Miocene and a the subsequent development of aridity. To this end, we estimate divergence times and likely biogeographical origins of the major clades in the phylogeny of Heliotropium, using both Bayesian and likelihood methods. Divergence times of all Andean clades in Heliotropium are estimated to be of late Miocene or Pliocene ages. At least three independent Andean diversification events can be recognized within Heliotropium. Timing of the diversification in the Andean lineages Heliotropium sects.Heliothamnus, Cochranea, Heliotrophytum, Hypsogenia, Plagiomeris, Platygyne clearly correspond to a rapid, late Miocene uplift of the Andes and a Pliocene development of arid environments in South America.

Testing Hypotheses on Disjunctions Present in the Primarily Woody Boraginales: Ehretiaceae, Cordiaceae, and Heliotropiaceae, Inferred from ITS1 Sequence Data

Hypotheses on the origin of the current distribution patterns and bicontinental disjunctions of Cordiaceae, Ehretiaceae, and Heliotropiaceae (Primarily Woody Boraginales) are tested by pairwise comparison of Kimura two‐parameter distances. Estimated absolute dates of fossils and geological events (plate tectonics, climate changes) were used to calibrate a molecular clock. A mid‐Cretaceous origin of the Primarily Woody Boraginales is proposed with an initial diversification in South America. Plate tectonics appear to play a minor role in their phylogeography. Most disjunctions are best explained by the rare events of long‐distance dispersal because of the widespread occurrence of drupaceous fruits and their potential for endozoochoria. Furthermore, migrations and extinctions might have played a considerable role in the formation of the current distribution patterns.

Non-coding chloroplast DNA for plant molecular systematics at the infrageneric level

With primers constructed against highly conserved regions of tRNA genes (trnTUGU, trnLUAA and trnFGAA) in chloroplast DNA, we have amplified two different non-coding spacers and one intron from four species within the genus Echium L. (Boraginaceae) and from two confamilial outgroups. The trnTUGU-trnLUAA intergenic spacer contains a greater number of polymorphic sites than the trnLUAA intron or the trnLUAA-trnFGAA intergenic spacer. We analyzed a total of 11 kb of sequence data from this non-coding DNA. Total nucleotide divergence between Echium species is on the order of 1% for these regions, all of which possess infrageneric length polymorphisms. The latter two regions contain indels which occur only in the 14 Macaronesian Island endemic species of Echium studied and suggest that these may form a monophyletic group.

Fossil and Extant Western Hemisphere Boragineae, and the Polyphyly of “Trigonotideae” Riedl (Boraginaceae: Boraginoideae)

Abstract Boraginaceae tribe Trigonotideae comprises a heterogenous assemblage of taxa, many of which have been shown to belong to widely divergent lineages in Boraginaceae in the recent past, with some taxa now assigned to three of the four currently recognized tribes of the Boraginaceae s. s., namely the Cynoglosseae, Echiochileae, and Lithospermeae. The systematics of Moritzia and Thaumatocaryon, the only endemic South American genera of Boraginaceae, have been controversially discussed in the past, and their most recent placement was in Trigonotideae. The present study investigates the phylogenetic relationships of “Trigonotideae” based on micromorphology and molecular data (ITS including 5.8S rRNA, and the trnL-trnF spacer). Molecular data show that “Trigonotideae” are polyphyletic, and none of its members is at all closely related to Trigonotis itself. Moritzia and Thaumatocaryon are closely allied to each other and are the sister group of the Old World Boragineae. Flowers, pollen, and fruit morphology strongly support this systematic placement. Extant (native) Boragineae are absent from North America and had not previously been reported from South America, whereas members of the Cynoglosseae, Echiochileae, and Lithospermeae have been reported from both continents. Moritzia and Thaumatocaryon are thus the only native representatives of Boragineae in the Americas and represent an unexpected western Eurasian/South American disjunction. However, several (widespread and abundant) fossil taxa from the Cenozoic of North America (especially species of †Prolithospermum) can be confidently placed into Boragineae. Extant Moritzia /Thaumatocaryon likely go back to a lineage which reached North America from Europe and then migrated into South America, with subsequent extinction in North America.

Leaf anatomy and foliar trichomes in Heliotropiaceae and their systematic relevance

Summary Leaf anatomy and the distribution of foliar trichome types of 65 species of Heliotropiaceae have been investigated. The aim was to evaluate the systematic relevance of their diversity as compared to recent findings of systematic relationships within the family. The results of leaf anatomy patterns, especially venation, vascular system, various foliar trichome types, and localization of crystals are of surprisingly high systematic value and prove the actual proposed subdivision of this family based on molecular results. Each main clade identified in the molecular studies is well characterized on the basis of leaf anatomy.

The gametophyte-sporophyte junction: unequivocal hints for two evolutionary lines of archegoniate land plants

Summary New results have added to our knowledge about the gametophyte-sporophyte junction in bryophytes, hornworts and pteridophytes and its significance for archegoniate land plant evolution. Bryophyta (liverworts and mosses) show a uniform structure: the sporophyte foot is separated from the surrounding gametophyte tissue by a placental space. At maturity the space is in most cases filled with residues of collapsed cells of gametophyte origin. The taxa with a placental space represent the bryophyte lineage of land plant evolution, indicating a common ancestor of the bryophyte groups Hepaticophytina and Bryophytina. To emphasize the separate position of Fossombronia within liverworts, the new class Fossombroniopsida is proposed. In Anthocerotophyta and Psilotopsida sporophyte haustorial cells intermingle resp. interdigitate with gametophyte transfer cells, and electron-dense fibrillar material fills the interface. In Lycopodiopsida, Equisetopsida and Pteridopsida, a direct contact exists between gametophyte and sporophyte placental layers. In some cases, sporophyte placental cells tend to interdigitate between gametophyte placental cells. No residues of collapsed gametophyte cells are found in the interface between the two generations.

Familial classification of the Boraginales

The Boraginales are now universally accepted as monophyletic and firmly placed in Lamiidae. However, a consensus about familial classification has remained elusive, with some advocating recognition of a single, widely variable family, and others proposing recognition of several distinct families. A consensus classification is proposed here, based on recent molecular phylogenetic studies, morphological characters, and taking nomenclatural stability into consideration. We suggest the recognition of eleven, morphologically well-defined and clearly monophyletic families, namely the Boraginaceae s.str., Codonaceae, Coldeniaceae fam. nov., Cordiaceae, Ehretiaceae, Heliotropiaceae, Hoplestigmataceae, Hydrophyllaceae, Lennoaceae, Namaceae, and Wellstediaceae. Descriptions, synonomy, a taxonomic key, and a list of genera for these eleven families are provided, including the new family Coldeniaceae (monogeneric) and Namaceae (segregated from Hydrophyllaceae and comprising Nama, Eriodictyon, Turricula, and Wigandia), the latter necessitating a revised circumscription of a more morphologically coherent Hydrophyllaceae.

From capsules to nutlets—phylogenetic relationships in the Boraginales

Multiple family‐level subdivisions of Boraginales have been proposed in the past. The relationships of several constituent genera have been enigmatic, including Codon (Codonaceae), Hoplestigma (Hoplestigmataceae), Pholisma (Lennoaceae), Vahlia (Vahliaceae), and Wellstedia (Wellstediaceae), all of which are included in the present study. We present a molecular analysis with four chloroplast loci, including 89 ingroup taxa and a broad outgroup sampling in the asterids. The genus Vahlia is excluded from Boraginales and appears to represent an early branching lineage of Lamiales. The study provides a well supported topology for the relationships within Boraginales, including all of the genera with previously unclear relationships. Within Boraginales, two major clades are recognized, with “herbaceaous” Boraginales I resolved as [Codonaceae,[Wellstediaceae,[Boraginaceae]]] and “woody” Boraginales II resolved as [Hydrophyllaceae I,[Hydrophyllaceae II,[Heliotropiaceae,[Cordiaceae,[Ehretiaceae,Lennoaceae]]]]. A close relationship between Ehretiaceae and Lennoaceae is well supported, but the exact placement of Lennoaceae remains unresolved. The Cordiaceae lineage includes the monotypic genus Coldenia and the aberrant western and central African genus Hoplestigma. Woody Boraginales II are retrieved in two highly supported clades. Hydrophyllaceae are retrieved in two separate clades, but with poor support. There appear to be clear morphological progressions in vegetative, floral, and fruit morphology in both major Boraginales lineages. Thus capsular fruits are found in the first branching lineages of both clades, whereas reduced seed numbers in indehiscent fruits predominate in the more derived phylogenetic positions. Based on these results, we advocate the recognition of eight morphologically well defined clades in the order, namely Boraginaceae s.str., Codonaceae, Cordiaceae (incl. Coldenia and Hoplestigmataceae), Ehretiaceae (incl. Lennoaceae), Heliotropiaceae, Hydrophyllaceae I and Hydrophyllaceae II, and Wellstediaceae.

Molecular phylogeny, morphology and taxonomic re-circumscription of the generic complex Nonea/Elizaldia/Pulmonaria/Paraskevia (Boraginaceae-Boragineae)

We performed a molecular phylogenetic analysis of the generic complex Nonea/Elizaldia/Paraskevia/ Pulmonaria (Boraginaceae-Boragineae), using trn L UAA and ITS1 sequences from non-coding plastid and nuclear DNA, respectively. In the strict consensus of most parsimonious trees from combined ITS1/trnL sequences the ingroup forms a monophyletic group with two sister clades of Nonea/Elizaldia and Paraskevia/ Pulmonaria. The eastern Mediterranean Nonea ohtusifolia is sister to the rest of the ingroup and more distant to Nonea taxa than to those of Pulmonaria. Elizaldia is firmly nested in Nonea and forms a clade that includes the southern Mediterranean species N. vesicaria. Nonea as currently circumscribed is therefore paraphyletic. The molecular results are congruent with morphological, karyological and chorological features and suggest a rede-finition of Nonea s.l. based on monophyletic groups. We propose: (i) the institution of the new monotypic genus Melanortocarya gen. nov. for N. ohtusifolia, (ii) the inclusion of Elizaldia within Nonea, and (iii) the transfer of Paraskevia (Nonea) cesatiana to Pulmonaria. Nonea embergeri, previously treated at the infraspecific level, is recognized at species rank and E. calycina subsp. multicolor is placed in synonymy of N. calycina.