The history of a nearctic colonization: molecular phylogenetics and biogeography of the Nearctic toads (Bufo)

Previous hypotheses of phylogenetic relationships among Nearctic toads (Bufonidae) and their congeners suggest contradictory biogeographic histories. These hypotheses argue that the Nearctic Bufo are: (1) a polyphyletic assemblage resulting from multiple colonizations from Africa; (2) a paraphyletic assemblage resulting from a single colonization event from South America with subsequent dispersal into Eurasia; or (3) a monophyletic group derived from the Neotropics. We obtained approximately 2.5 kb of mitochondrial DNA sequence data for the 12S, 16S, and intervening valine tRNA gene from 82 individuals representing 56 species and used parametric bootstrapping to test hypotheses of the biogeographic history of the Nearctic Bufo. We find that the Nearctic species of Bufo are monophyletic and nested within a large clade of New World Bufo to the exclusion of Eurasian and African taxa. This suggests that Nearctic Bufo result from a single colonization from the Neotropics. More generally, we demonstrate the utility of parametric bootstrapping for testing alternative biogeographic hypotheses. Through parametric bootstrapping, we refute several previously published biogeographic hypotheses regarding Bufo. These previous studies may have been influenced by homoplasy in osteological characters. Given the Neotropical origin for Nearctic Bufo, we examine current distributional patterns to assess whether the Nearctic-Neotropical boundary is a broad transition zone or a narrow boundary. We also survey fossil and paleogeographic evidence to examine potential Tertiary and Cretaceous dispersal routes, including the Paleocene Isthmian Link, the Antillean and Aves Ridges, and the current Central American Land Bridge, that may have allowed colonization of the Nearctic.     

Phylogenetic relationships within the South American fish family Anostomidae (Teleostei,Ostariophysi, Characiformes)

Analysis of a morphological dataset containing 152 parsimony‐informative characters yielded the first phylogenetic reconstruction spanning the South American characiform family Anostomidae. The reconstruction included 46 ingroup species representing all anostomid genera and subgenera. Outgroup comparisons included members of the sister group to the Anostomidae (the Chilodontidae) as well as members of the families Curimatidae, Characidae, Citharinidae, Distichodontidae, Hemiodontidae, Parodontidae and Prochilodontidae. The results supported a clade containing Anostomus, Gnathodolus, Pseudanos, Sartor and Synaptolaemus (the subfamily Anostominae sensu Winterbottom) albeit with a somewhat different set of relationships among the species within these genera. Anostomus as previously recognized was found to be paraphyletic and is split herein into two monophyletic components, a restricted Anostomus and the new genus Petulanos gen. nov. , described herein. Laemolyta appeared as sister to the clade containing Anostomus, Gnathodolus, Petulanos, Pseudanos, Sartor and Synaptolaemus. Rhytiodus and Schizodon together formed a well‐supported clade that was, in turn, sister to the clade containing Anostomus, Gnathodolus, Laemolyta, Petulanos, Pseudanos, Sartor and Synaptolaemus. Anostomoides was sister to the clade formed by these nine genera. Leporinus as currently defined was not found to be monophyletic, although certain clades within that genus were supported, including the species with subterminal mouths in the former subgenus Hypomasticus which we recognize herein as a genus. Abramites nested in Leporinus, and Leporellus was found to be the most basal anostomid genus. The presence of cis‐ and trans‐Andean species in Abramites, Leporellus, Leporinus and Schizodon, all relatively basal genera, suggests that much of the diversification of anostomid species pre‐dates the uplift of the Andean Cordilleras circa 11.8 million years ago. Several important morphological shifts in anostomid evolution are illustrated and discussed, including instances of convergence and reversal. © 2008 The Linnean Society of London, Zoological Journal of the Linnean Society, 2008, 154 , 70–210.     

Around the world in 10 million years: biogeography of the nearly cosmopolitan true toads (Anura: Bufonidae)

Aim The species‐rich family of true toads (Anura: Bufonidae) has been the focus of several earlier studies investigating the biogeography of geographically widespread taxa. Herein, we employ newly developed Bayesian divergence estimate methods to investigate the biogeographical history of this group. Resulting age estimates are used to test several key temporal hypotheses including that the origin of the bufonid clade pre‐dates Gondwanan vicariance (~105 million years ago, Ma). Area cladograms are also invoked to investigate the geographical origin of the family. Location Worldwide, except the Australia–New Guinea plate, Madagascar and the Antarctic. Methods A phylogenetic hypothesis of the relationships among true toads was derived from analysis of 2521 bp of DNA data including fragments from three mitochondrial (12S, tRNA^val, 16S) and two nuclear (RAG‐1, CXCR‐4) genes. Analysis of multiple, unlinked loci with a Bayesian method for estimating divergence times allowed us to address the timing and biogeographical history of Bufonidae. Resulting divergence estimates permitted the investigation of alternative vicariance/dispersal scenarios that have been proposed for true toads. Results Our area cladogram resulting from phylogenetic analysis of DNA data supports a South American origin for Bufonidae. Divergence estimates indicate that the family originated earlier than had been suggested previously (78–99 Ma). The age of the enigmatic Caribbean clade was dated to the late Palaeocene–early Eocene. A return of bufonids to the New World in the Eocene was followed by rapid diversification and secondary expansion into South America by the early Oligocene (Rupelian). Main conclusions The South American origin of Bufonidae in the Upper Cretaceous was followed by relatively rapid expansion and radiation around the globe, ending with a return to the Americas via a Eurasian/North American land bridge in the Eocene. Though the exact route of this dispersal (Beringia or North Atlantic) remains unclear, an argument is made for the less frequently invoked North Atlantic connection. The origin of the enigmatic Caribbean lineage was found to be consistent with colonization following the bolide impact at the K/T boundary. These findings provide the first, firm foundation for understanding true toad divergence times and their truly remarkable and global radiation.     

Phylogeny of the neotropical moth tribe Josiini (Notodontidae: Dioptinae): comparing and combining evidence from DNA sequences and morphology

DNA sequences were gathered from mitochondrial COII and nuclear ribosomal 18S and 28S genes for 21 moth species in the tribe Josiini (Notodontidae: Dioptinae) and two outgroup genera. These data complement a previously published morphological character set for the same taxa. We examine whether relationships in the Josiini are best reflected by a single phylogenetic analysis of all the data, or by a consensus of separate trees generated from DNA and morphology. Even in cases where analyses of partitioned data produce incongruent cladograms, the underlying disagreement between partitions is relatively small. While both molecular and morphological data provide useful character information by themselves, we conclude that the best supported phylogenetic hypothesis is the one derived from combined analysis.     

Phylogeny of east asian bufonids inferred from mitochondrial DNA sequences (Anura: amphibia)

We investigated the relationships of Asian bufonids using partial sequences of mitochondrial DNA genes. Twenty-six samples representing 14 species of Bufo from China and Vietnam and 2 species of Torrentophryne from China were examined. Three samples of Bufo viridis from Armenia and Georgia were also sequenced to make a comparison to its sibling tetraploid species B. danatensis. Bufo americanus, from Canada, was used as the outgroup. Sequences from the 12S ribosomal RNA, 16S ribosomal RNA, cytochrome b, and the control region were analyzed using parsimony. East Asian bufonids were grouped into two major clades. One clade included B. andrewsi, B. bankorensis, B. gargarizans, B. tibetanus, B. tuberculatus, its sister clade B. cryptotympanicus, and the 2 species of Torrentophryne. The second clade consisted of B. galeatus, B. himalayanus, B. melanostictus, and a new species from Vietnam. The placement of three taxa (B. raddei, B. viridis, and its sister species, B. danatensis) was problematic. The genus Torrentophryne should be synonymized with Bufo to remove paraphyly. Because B. raddei does not belong to the clade that includes B. viridis and B. danatensis, it was removed from the viridis species group. The species status of B. bankorensis from Taiwan is evaluated.     

Recent colonization and radiation of North American Lycaeides (Plebejus) inferred from mtDNA

North American Lycaeides populations exhibit remarkable variation in ecological, morphological, and behavioral characters, as well as an established history of introgressive hybridization. We examined mitochondrial DNA variation from 55 Eurasian and North American Lycaeides populations using molecular phylogenetics and coalescent-based methods in order to clarify the evolutionary and demographic history of this polytypic group. Specifically we addressed the following questions: (1) Do mitochondrial alleles sampled from North America form a monophyletic group, which would be expected if North American Lycaeides were descended from a single Eurasian ancestor? (2) When did Lycaeides colonize North America? and (3) What is the demographic history of North American Lycaeides since their colonization? Bayesian maximum likelihood methods identified three major mitochondrial lineages for Lycaeides; each lineage contained haplotypes sampled from both Eurasia and North America. This suggests a complex colonization history for Lycaeides, which likely involved multiple founding lineages. Coalescent-based analyses placed the colonization of North America by Eurasian Lycaeides sometime during or after the late Pliocene. This was followed by a sudden increase in population size of more than an order of magnitude for the North American population of Lycaeides approximately 100,000-150,000 years before the present. These mitochondrial data, in conjunction with data from previous ecological, morphological, and behavioral studies, suggest that the diversity observed in Lycaeides in North America is the result of a recent evolutionary radiation, which may have been facilitated, in part, by hybridization.     

Comparative morphology of pond,stream and phytotelm‐dwelling tadpoles of the South American Redbelly Toads (Anura: Bufonidae: Melanophryniscus)

We present a comprehensive review of larval morphology in the Neotropical toad genus Melanophryniscus. The taxa studied included 23 species with representatives of recognized phenetic groups and different larval ecomorphological guilds: pond, stream, and phytotelm‐dwelling tadpoles. Their external morphology variation is congruent with current phenetic arrangement based on adult features, but also reflects the habitat where larvae develop. Lotic tadpoles (i.e. M. tumifrons group and M. krauczuki) in general exhibit a more depressed body, a longer tail with lower fins, and larger oral discs than lentic forms (i.e. M. stelzneri group, M. moreirae, M. sanmartini, and M. langonei). Despite their peculiar, confined microhabitat, phytotelm larvae do not diverge markedly from non‐arboreal species. The distinctive features of all species are the presence of a pineal end organ and the placement of the intestinal reversal point at the left of the abdomen in typical larval stages. The buccal cavity and musculoskeletal anatomy are quite conserved between species, yet some characteristics differ from those of other bufonids. The presence of one pair of subhyoid muscles is apparently an exclusive trait of Melanophryniscus among Bufonidae. © 2014 The Linnean Society of London, Biological Journal of the Linnean Society, 2014, 112 , 417–441.     

Phylogeny of the Trichostrongylina (Nematoda) inferred from 28S rDNA sequences

We produced a molecular phylogeny of species within the order Strongylida (bursate nematodes) using the D1 and D2 domains of 28S rDNA, with 23 new sequences for each domain. A first analysis using Caenorhabditis elegans as an outgroup produced a tree with low resolution in which three taxa (Dictyocaulus filaria, Dictyocaulus noerneri, and Metastrongylus pudendotectus) showed highly divergent sequences. In a second analysis, these three species and C. elegans were removed and an Ancylostomatina, Bunostomum trigonocephalum, was chosen (on the basis of previous morphological analyses) as the outgroup for an analysis of the phylogenetic relationships between and within the Strongylina (strongyles) and Trichostrongylina (trichostrongyles). A very robust tree was obtained. The Trichostrongylina were monophyletic, but the Strongylina were paraphyletic, though this requires confirmation. Within the Trichostrongylina, the three superfamilies defined from morphological characters are confirmed, with the Trichostrongyloidea sister group to a clade including the Molineoidea and Heligmosomoidea. Within the Trichostrongyloidea, the Cooperiidae, Trichostrongylidae, and Haemonchidae were polytomous, the Haemonchinae were monophyletic, but the Ostertagiinae were paraphyletic. The sister-group relationships between Molineoidea and Heligmosomoidea were unsuspected from previous morphological analysis. No unequivocal morphological synapomorphy could be found for the grouping Molineoidea + Heligmosomoidea, but none was found which contradicted it.     

A New Species of Leptolalax （Anura： Megophryidae） from Southern China

A new species, Leptolalax laui sp. nov. is described based on specimens collected from Hong Kong and Shenzhen City, Guangdong Province, China. The new species can be distinguished from other known congeners by morphological and molecular data. The new species is characterized by the following characters： 1） small size （adult males SVL 24.8.1 mm-26.7 mm）; 2） near immaculate creamy white chest and belly; 3） broad lateral fringes on toes; 4） head longer or as long as wide; 5） distinct dark brown spots in flank; 6） moderate dermal fringes on fingers; 7） brown or reddish-brown dorsum with fine round scattered tubercles; 8） thin traverse brownish-grey bars on the dorsal surface of tibia and lower arms; 9） longitudinal ridges under toes not interrupted at the articulations.     

Molecular systematics of the caracaras and allies (Falconidae: Polyborinae) inferred from mitochondrial and nuclear sequence data

The Polyborinae is the most diverse subfamily of the Falconidae in terms of both morphology and behaviour, and includes falconet‐shaped birds (Spiziapteryx), arboreal omnivores (Daptrius, Ibycter), as well as terrestrial generalists and scavengers (Caracara, Milvago and Phalcoboenus). The Polyborinae are endemic to the New World, with all but one species (Caracara cheriway) being restricted to Central and South America. Using over 7300 bp of mitochondrial and nuclear sequence data, we aim to clarify the taxonomy and biogeography of the Polyborinae. The genus Milvago was unexpectedly found to be polyphyletic, with Chimango Caracara Milvago chimango being related to the genus Phalcoboenus and Yellow‐headed Caracara Milvago chimachima being sister to Daptrius. Furthermore, very low genetic divergence was found among the four species of the genus Phalcoboenus, with the lowest divergence being between White‐throated Caracara Phalcoboenus albogularis and Mountain Caracara Phalcoboenus megalopterus. Our divergence time analyses revealed that the Polyborinae started to diversify in the Miocene, at about 14 Ma, and that the generalist/scavenger behaviour in the Falconidae appeared between 14 and 6.6 Ma. All speciation events within the caracaras occurred during the Pleistocene. This situation differs from the general pattern described for forest birds, in which most diversification events are older, occurring primarily in the Pliocene and Miocene.     

The anatomy of the basal ornithischian dinosaur Eocursor parvus from the lower Elliot Formation (Late Triassic) of South Africa

Ornithischia is a morphologically and taxonomically diverse clade of dinosaurs that originated during the Late Triassic and were the dominant large‐bodied herbivores in many Cretaceous ecosystems. The early evolution of ornithischian dinosaurs is poorly understood, as a result in part of a paucity of fossil specimens, particularly during the Triassic. The most complete Triassic ornithischian dinosaur yet discovered is Eocursor parvus from the lower Elliot Formation (Late Triassic: Norian–Rhaetian) of Free State, South Africa, represented by a partial skull and relatively complete postcranial skeleton. Here, the anatomy of Eocursor is described in detail for the first time, and detailed comparisons are provided to other basal ornithischian taxa. Eocursor is a small‐bodied taxon (approximately 1 m in length) that possesses a plesiomorphic dentition consisting of unworn leaf‐shaped crowns, a proportionally large manus with similarities to heterodontosaurids, a pelvis that contains an intriguing mix of plesiomorphic and derived character states, and elongate distal hindlimbs suggesting well‐developed cursorial ability. The ontogenetic status of the holotype material is uncertain. Eocursor may represent the sister taxon to Genasauria, the clade that includes most of ornithischian diversity, although this phylogenetic position is partially dependent upon the uncertain phylogenetic position of the enigmatic and controversial clade Heterodontosauridae. © 2010 The Linnean Society of London, Zoological Journal of the Linnean Society, 2010, 160 , 648–684.     

Molecular and morphological divergence in the butterfly genus Lycaeides (Lepidoptera: Lycaenidae) in North America: evidence of recent speciation

Male genital morphology, allozyme allele frequencies and mtDNA sequence variation were surveyed in the butterfly species Lycaeides idas and L. melissa from across much of their range in North America. Despite clear differences in male genital morphology, wing colour patterns and habitat characteristics, genetic variation was not taxonomically or geographically structured and the species were not identifiable by either genetic data set. Genetic distances (Nei's D=0.002–0.078, calculated from allozyme data) between all populations of both species were within the range commonly observed for conspecific populations of other butterflies. The most frequent mtDNA haplotype was present in individuals of both species in populations from southern California to Wisconsin. We conclude that speciation has probably happened recently and the lack of genetic differentiation between the species is the product of either (1) recent or ongoing gene flow at neutral loci, and/or (2) an insufficiency of time for lineage sorting. The evolution of male genital morphology, wing colour patterns and ecological characteristics has proceeded more rapidly than allozyme or mtDNA evolution.     

Historical biogeography of the Andean region: evidence from Listroderina (Coleoptera: Curculionidae: Rhytirrhinini) in the context of the South American geobiotic scenario

The weevil subtribe Listroderina belongs in the tribe Rhytirrhinini (subfamily Cyclominae), and has 25 genera and 300 species in the Americas. The distributional history of this subtribe was reconstructed applying dispersal-vicariance analysis (DIVA) using its genera as terminals. The results suggest that Listroderina originated within an area presently represented by the Central Chile, Paramo, Puna, Patagonia and Subantarctic subregions of the Andean region. Posteriorly, the subtribe was affected by extinctions and was confined to Central Chile, Paramo and Subantarctic subregions. Later, extinctions and dispersals took place and the subtribe was restricted to the Paramo and Puna subregions. From there, a dispersal event to the Subantarctic subregion occurred, enlarging again the geographical range of the subtribe. Subsequently, a vicariant event separated the Puna and Paramo subregions from the Subantarctic one. While the Macrostyphlus generic group was confined to the Paramo and Puna subregions and from there dispersed to other areas, the Antarctobius , Falklandius , Listronotus , and Listroderes generic groups diversified in the Subantarctic subregion. The results obtained by DIVA may be linked to major geological events of South America. Thus, the geobiotic scenarios recorded in this subcontinent since the late Cretaceous could be used to interpret the biogeographical events which drove Listroderina evolution.  © 2003 The Linnean Society of London, Biological Journal of the Linnean Society , 2003, 80 , 339–352.     

Phylogeny and biogeography of Valerianaceae (Dipsacales) with special reference to the South American valerians

Species of Valerianaceae are a common component of the alpine flora throughout the Northern Hemisphere as well as the Andes of South America. Sequence data from three chloroplast markers (psbA-trnH intron, trnK-matK intron, and the trnL-F region) along with the internal transcribed spacer region (ITS) of nuclear ribosomal DNA were used to infer relationships within Valerianaceae. Both genomes, as well as a combined data set, provide support for the major clades within the group and do not support a monophyletic Valeriana. In addition, these data indicate that Plectritis is nested within South American Valeriana, as opposed to being sister to Centhranthus as previously hypothesized. Valerianaceae appear to have originated in Asia, probably in the Himalayas, and subsequently to have dispersed several times to Europe and to the New World. Our results imply that Valerianaceae colonized South America on multiple occasions from the north. In one of these cases there appears to have been a substantial and rapid radiation, primarily in the high elevation paramo habitat. A variety of methods were used to estimate divergence times to determine when Valerianaceae might have colonized South America. Regardless of the method and fossil constraints applied, our estimates suggest that Valerianaceae colonized South America prior to the formation of the Isthmus of Panama.     

Phylogeny of Barnadesioideae (Asteraceae) inferred from DNA sequence data and morphology

Subfamily Barnadesioideae (Asteraceae) consists of nine genera and 91 species endemic to South America. They include annual and perennial herbs, arching shrubs and trees up to 30 m tall. Presumed sister to all other Asteraceae, its intergeneric relationships are key to understanding the early evolution of the family. Results of the only molecular study on the subfamily conflict with relationships inferred from morphology. We investigate inter- and intrageneric relationships in Barnadesioideae with novel DNA sequence data and morphological characters using parsimony, likelihood and Bayesian inference. All results verify Barnadesioideae as monophyletic and sister to the rest of the family. A basal split within the subfamily is recognized, with Chuquiraga, Doniophyton and Duseniella in one clade, and Arnaldoa, Barnadesia, Dasyphyllum, Fulcaldea, Huarpea and possibly Schlechtendalia in another. The largest genus, Dasyphyllum, is revealed as biphyletic with the two clades separating along subgeneric and geographic lines. Schlechtendalia, suggested as the earliest diverging lineage of the subfamily by morphological studies and parsimony analyses, is found in a more derived position under model-based inference methods. Competing phylogenetic hypotheses, both previous and present, are evaluated using likelihood-based tests. Evolutionary trends within Barnadesioideae are inferred: hummingbird pollination has developed convergently at least three times. An early vicariance in the subfamily’s distribution is revealed. X = 9 is supported as the ancestral base chromosome number for both Barnadesioideae and the family as a whole.     

Phylogeny and evolution of the South African genus Metalasia (Asteraceae–Gnaphalieae) inferred from molecular and morphological data

Metalasia is a genus in tribe Gnaphalieae (Asteraceae), endemic to South Africa and with its main distribution in the Cape Floristic Region. The genus comprises 57 species and, with a number of closely related genera, it constitutes the ‘Metalasia clade’. A species‐level phylogenetic analysis is presented, based on DNA sequences from two nuclear (internal and external transcribed spacer: ITS, ETS) and two plastid (psbA‐trnH, trnL‐trnF) regions together with morphological data. Analyses combining molecular and morphological data attempt not only to resolve species interrelationships, but also to detect patterns in character evolution. Phylogenetic analyses corroborate our earlier study and demonstrate that Metalasia is formed of two equally sized, well‐supported sister groups, one of which is characterized by papillose cypselas. The results differ greatly from earlier hypotheses based on morphology alone, as few morphological characters support the phylogenetic patterns obtained. The two clades of Metalasia do, however, appear to differ in distribution, corresponding to the different rainfall regimes of South Africa. Analyses show a few taxa to be problematic; one example is the widely distributed M. densa which appears to be an intricate species complex. © 2013 The Linnean Society of London, Botanical Journal of the Linnean Society, 2014, 174 , 173–198.     

Evolution in Aeschynanthus (Gesneriaceae) inferred from ITS sequences

 Aeschynanthus Jack, an epiphytic genus with c.160 species, is widespread in SE Asia. We selected 50 species for ITS nrDNA sequencing, to include all biogeographic areas and all infrageneric groupings, which are currently based on seed morphology. Some species were sequenced directly from PCR product; others cloned because of ITS length polymorphisms. The clone sequences were analysed individually and combined in an elision matrix. Results extend earlier findings that Aeschynanthus is divided into two clades, one occurring primarily in mainland SE Asia and the other in Malesia. This pattern is interpreted as indicating an ancient vicariance event followed by dispersal and plate fusion. Clade I has straight or clockwise spiral orientation of the testa cells and clade II anticlockwise spiral orientation. In clade I some species of section Microtrichium form a basal group with other sections being polyphyletic or paraphyletic. In clade II the monophyletic section Aeschynanthus is nested within the paraphyletic basal Microtrichium. Received February 8, 2001 Accepted June 8, 2001     

Phylogenetic relationships and biogeography of midwife toads (Discoglossidae: Alytes)

Aim To devise a robust phylogenetic hypothesis for midwife toads (Alytes: Anura: Discoglossidae) and to discuss its implications for the reconstruction of the biogeographical history of the group. Location Western Palearctic. Methods Analysis of sequences of mitochondrial DNA (cytochrome b and 16S RNA, 861 bp) and 29 characters of cranial osteology of all species and subspecies within Alytes. Results Phylogenetic analyses support a sister group relationship between Alytes dickhilleni and A. muletensis, and of this clade with A. maurus. The monophyly of A. obstetricans is controversial; in particular, the phylogenetic position of A. obstetricans almogavarii is uncertain. The estimated dates for the cladogenetic events within Alytes are congruent with those derived from independent analyses (allozymes), except for the differentiation of A. o. almogavarii and the split between A. dickhilleni and A. muletensis. Main conclusions The phylogeny based on the analysis of morphological and mtDNA data differs from previous hypotheses in the positions of A. o. almogavarii and A. maurus. Events associated with the radiation of Alytes are the formation of large inland saline lakes in Iberia c. 16 Ma and the 11 ° C dramatic decrease in average annual temperature during the Middle–Late Badenian transition c. 14–13.5 Ma (A.cisternasii vs. the ancestor of the remaining clades), the structuring of the Neo‐Pyrenees and the reopening of the Betic Strait c. 10–8 Ma(A. o. almogavarii vs. A. obstetricans and vs. the subgenus Baleaphryne), the opening of the Gibraltar Strait at the end of the Messinian Salinity Crisis at c. 5.3 Ma (A. maurus vs. the ancestor of the A. dickhilleni A. muletensis clade) and a transmarine colonization event at c. 3 Ma (the ancestor of A. muletensis vs. A. dickhilleni). Following the new hypothesis, A. maurus, previously considered a subspecies of A. obstetricans, deserves species status. Second, A. o. almogavarii is a well‐differentiated lineage that was isolated from other A. obstetricans more than c. 5 Ma, but later lost its genetic and specific identity following secondary contact, hybridization and introgression with the main stock. The presence of a marked morphological and genetic diversity within A. obstetricans renders reconstruction of the evolutionary history of the genus more complicated than previously appreciated.