Phylogenetics of the australasian mudfishes: evolution of an eel-like body plan

The mudfish genus Neochanna (Osmeriformes: Galaxiidae) contains six species that exhibit varying degrees of morphological and ecological adaptation to life in swampy conditions. Here, we present the first molecular phylogenetic analysis (16S rRNA+cytochrome b; 1681bp) of the entire genus to (1) test for monophyly of Australian and New Zealand taxa and (2) elucidate morphological character evolution. In addition, we analyse a matrix of 21 morphological characters to test for congruence between mitochondrial DNA and morphology, and to examine total evidence under a Bayesian framework. Molecular data indicate that the diadromous Tasmanian mudfish, N. cleaveri, is sister to a clade of five non-diadromous New Zealand mudfishes. Mapping of morphological characters onto the molecular phylogeny suggests an evolutionary transition from a plesiomorphic "stream" galaxiid morphotype to a more specialised "anguilliform" galaxiid morphotype. Pelvic fins have become increasingly reduced and dorsal, anal, and caudal fins are increasingly confluent. Associated with these changes are elongated nostrils, reduced eyes, and increased anterior cranial ossification. Morphological and total evidence analyses yield similar or identical topologies, respectively. The phylogenetic distribution of diadromy in Neochanna is consistent with a single loss of this character state in New Zealand. However, the strong sister relationship (3.6% divergent; 100% bootstrap support) detected between non-diadromous N. burrowsius (South Island, NZ) and N. rekohua (Chatham Islands) indicates geologically recent dispersal across 850km of ocean. Diadromy may therefore have been retained in the common ancestor of these two mudfish species, and subsequently lost from both lineages.     

Small subunit rDNA and Bayesian inference reveal Pectenophilus ornatus (Copepoda incertae sedis) as highly transformed Mytilicolidae, and support assignment of Chondracanthidae and Xarifiidae to Lichomolgoidea (Cyclopoida)

Phylogenetic analysis of newly obtained data from the complete small subunit rDNA (18S) nuclear gene of a wide range of copepods placed the enigmatic Pectenophilus ornatus firmly in the Cyclopoida. Both maximum parsimony tree reconstruction, and Bayesian analysis operating under the GTR + I + Γ model of nucleotide substitution, gave identical solutions and placed P. ornatus at the base of the poecilostome families, in apposition to the mytilicolid taxa. The recently suggested assignment to the Siphonostomatoida on the basis of a tubular mouth cone in the pygmy male was rejected not only by the molecular data but also by new morphological observations. Scanning electron microscopy revealed that the appendage previously interpreted as the mandible was in reality the maxilla, the presumptive ‘labium’ only an intermaxillary outgrowth of the ventral cephalic sclerite bearing the widely separated paragnaths, and that there was no basal fusion between the labrum and the ‘posterior lip’ as in genuine siphonostomatoids. Absence of mandibles and their functional replacement by the anteriorly displaced maxillae is a unique and robust apomorphy for the Mytilicolidae and placed unequivocally P. ornatus in that family. The morphology of male Pectenophilus probably evolved as a result of global progenesis, involving early sexual maturation at the metanauplius stage and the complete cessation of somite and limb development. The molecular data were also employed to examine the relationships of two other highly modified parasitic families, the Xarifiidae (inhabiting hard corals) and the Chondracanthidae (parasitic on marine demersal fishes). Our analyses rejected the previously proposed relationship between Xarifiidae and Vahiniidae and strongly supported an Anchimolgidae + (Rhynchomolgidae + Xarifiidae) clade as sister group to the Sabelliphilidae within a monophyletic Lichomolgoidea. The obtained topology suggests that the common ancestor of this clade had already established a symbiotic relationship with scleractinian corals and that host switching occurred only secondarily in the Rhynchomolgidae, involving predominantly other cnidarian and occasionally noncnidarian hosts. Reassessment of the morphology of Parangium provided new evidence for a relationship with the xarifiids, rendering its current position in the Serpulidicolidae extremely unlikely. Both parsimony and Bayesian analyses revealed an unexpected but strongly supported relationship between the Chondracanthidae and Pseudanthessiidae. This result contrasts with earlier views advocating affinity to the Synapticolidae or Lichomolgidae, but was congruent with the previously unnoticed morphological similarity in antennary armature patterns in the first copepodid stage. The morphological grounds used to establish the Lernaeosoleidae were shown to be secondarily derived characters shared with one or several chondracanthid genera. Particularly the similarity between the Lernaeosoleidae and Markevitchielinus demonstrated that the former evolved from a mesoparasitic ancestor within the Chondracanthidae and consequently should sink as a synonym of the latter. © 2006 The Linnean Society of London, Biological Journal of the Linnean Society, 2006, 87 , 403–425.     

Psammic Procyclopina (Copepoda, Cyclopoida) from the coast of Brazil

Procyclopina polyarthra Herbst is redescribed and three new species, P. maricopeba, P. feiticeira and P. uguaipuku , are described from intertidal interstitial waters. Procyclopina is distinguished within the family by the enditic setation of the maxilliped 0,1,3,4, the 19-segmented antennule, and three elements in the leg 5 exopod of the female. Procyclopina has its distribution restricted to the coast of Säo Paulo, Brazil. Procyclopina maricopeba sp. n. is distinguished from P. polyarthra by the three-segmented leg 5 in the male and by the length: width ratio of the genital double somite in the female. Procyclopina feiticeira sp. n. is unique in the genus by lacking the inner seta on legs 14 exp-I, and by the incomplete fusion of genital (seventh thoracic) and first abdominal somites in the female. Procyclopina uguaipuku sp. n. is characterized by the antennulary armature, by the caudal ramus (much longer than wide), and by the position of the proximal seta of the leg 4 enp-2 which is set on a protuberance on the posterior face. Morphological characters of Procyclopina are compared with those of other cyclopinids.     

Description of Eucyclops tziscao sp. n., E. angeli sp. n., and a new record of E. festivus Lindberg, 1955 (Cyclopoida,Cyclopidae, Eucyclopinae) in Chiapas,Mexico

Two new species of the freshwater cyclopoid genera Eucyclops are described, Eucyclops tziscao sp. n. and E. angeli sp. n. Both species belong to the serrulatus-group defined by morphological features such as: the presence of distal spinules or hair-like setae (groups N1 and N2) on frontal surface of antennal basis; the fourth leg coxa with a strong inner spine that bears dense setules on inner side, yet proximally naked (large gap) on outer side; and a 12-segmented antennule with smooth hyaline membrane on the three distalmost segments. Eucyclops tziscao sp. n. is morphologically similar to E. bondi and E. conrowae but differs from these species in having a unique combination of characters, including a caudal ramus 4.05±0.25 times as long as wide, lateral seta of Enp3P4 modified as a strong, sclerotized blunt seta, coxal spine of fourth leg with inner spinule-like setules distally, and sixth leg of males bearing a strong and long inner spine 2.3 times longer than median seta. Eucyclops angeli sp. n. can be distinguished by an unique combination of morphological features: the short caudal ramus; the long spine on the sixth antennular segment of A1; the presence of one additional group of spinules (N12’) on the caudal surface of A2; the presence of long setae in females, or short spinules in males on the lateral margin of fourth prosomite; the strong ornamentation of the intercoxal sclerite of P4, specially group I modified as long denticles; the distal modified setae of Exp3P3 and Exp3P4 in females and males; and the short lateral seta of P5. Finally, we report on a new record of E. festivus in México, and add data on morphology of the species.     

Larval and post-larval development of the branchiopod clam shrimp Cyclestheria hislopi (Baird, 1859) (Crustacea, Branchiopoda, Conchostraca, Spinicaudata)

The larval and post-larval development of Cyclestheria hislopi is examined by SEM. There are at least nine stages (excluding the adult) – six larval and three post-larval stages. The first four stages are passed within the egg-membrane. The larval and the post-larval phase are separated by a profound change in morphology that takes place between stages VI and VII. The larva shifts from a dorso-ventrally flattened 'larval' appearance up to stage VI to a laterally flattened, more 'adult' appearance from stage VII. New morphological data have been revealed by this study, including (1) a large and globular larval dorsal organ; (2) the carapace starts its development from the segments of the first and second maxillae; (3) the anterior ramus of the second antenna in adult Cyclestheria hislopi is the endopod, and the posterior ramus the exopod. Direct development of the brood in Cyclestheria hislopi – unique among conchostracans – is compared with that of the Cladocera. If Cyclestheria is the sister group to the Cladocera, as favoured in this work, the classical neoteny theory of the Cladocera must be reconsidered, as there is no particular similarity between any adults of the Cladocera and any of the larval stages of Cyclestheria . It is suggested that Cyclestheria displays the type of development present in a cladoceran ancestor. A comparison between Cyclestheria and the Upper Cambrian 'Orsten' fossil Rehbachiella kinnekullensis reveals a remarkable similarity in the endite morphology of the trunk limbs.     

The syndermatan phylogeny and the evolution of acanthocephalan endoparasitism as inferred from 18S rDNA sequences

The phylogeny of the Syndermata (Rotifera: Monogononta, Bdelloidea, Seisonidea; Acanthocephala: Palaeacanthocephala, Eoacanthocephala, Archiacanthocephala) is key to understanding the evolution of acanthocephalan endoparasitism from free-living ancestors. In the present study, maximum likelihood, distance/neighbor-joining, and maximum parsimony analyses have been carried out based on 18S rDNA data of 22 species (four new sequences). The results suggest a monophyletic origin of the Eurotatoria (Monogononta+Bdelloidea). Seison appears as the acanthocephalan sistergroup. Palaeacanthocephala split into an "Echinorhynchus"-and a "Leptorhynchoides"-group, the latter sharing a monophyletic origin with the Eoacanthocephala and Archiacanthocephala. As inferred from the phylogeny obtained acanthocephalan endoparasitism evolved from a common ancestor of Seison and Acanthocephala that lived epizoically on an early mandibulate. Probably, an acanthocephalan stem species invaded the mandibulate host, thus establishing an endoparasitic lifestyle. Subsequently, vertebrates (or gnathostomes) became part of the parasite's life cycle. In the stem line of the Archiacanthocephala, a terrestrial life cycle has evolved, with an ancestor of the Tracheata (Insecta, Myriapoda) acting as intermediate host.     

How many species of Diacyclops? New taxonomic characters and species richness in a freshwater cyclopid genus (Copepoda,Cyclopoida)

The genus Diacyclops Kiefer, 1927 emend. Morton (1985) includes more than 100 species, widely distributed in all kinds of freshwater environments, and is the richest genus in the family Cyclopidae. Traditionally, Diacyclops species were defined according to differences in a few morphological characters; some characters (number of antennulary segments, segmentation pattern of swimming legs) are useful only in the separation of species groups, others (length of caudal rami and caudal setae) are highly variable even within the same population. During the study of the D. languidoides-group, minute morphological characters were used to differentiate between species (spinulation pattern and setation of antennary basis, setation and aesthetasc shape of male antennule, setation of mandibulary palp and maxilliped, shape of leg 4 basis) which allow to identify several valid species up to now concealed under the name `Diacyclops languidoides' (Lilljeborg, 1901). The coexistence of up to six congeneric species in the same sampling area: (a) supports the validity of the proposed taxonomic characters, (b) demonstrates that species richness may be highly underestimated in freshwater cyclopoid assemblages in absence of good taxonomic practice; and (c) requires an ecological explanation of species coexistence. The role of morphologically based taxonomy in order to solve general problems of distributional ecology and theoretical biology is explored.     

Development of the synganglion and morphology of the adult nervous system in the mite Archegozetes longisetosus Aoki (Chelicerata,Actinotrichida, Oribatida)

Small arthropods show a highly condensed central nervous system, which is accompanied by the loss of the ancestral metameric organization. This results in the formation of one solid mass, a synganglion. Although numerous studies investigated the morphology of Archegozetes longisetosus, the organization of the nervous system is to date unknown. Using synchrotron X‐ray microtomography, we investigated the organization of the nervous system in the adult stage and the development of the synganglion over all five free‐living life stages (larva, proto‐, deuto‐, tritonymph and adult). The general morphology of the synganglion resembles that of other studied mites (in the classic sense) and ticks, being subdivided into a sub‐ and supraesophageal region, and consisting of cortex and neuropil. All nerves entering the walking legs except the first consist of two rami. This split is not based on a functional division into a motor and a sensory ramus, but both rami contain motor and sensory neurites. Within the synganglion, we found structures that resemble the ancestral metameric organization of the nervous system of arthropods. The development of the synganglion of A. longisetosus shows a more or less linear increase in volume, but cortex and neuropil grow at different rates over the five life stages. Between the second and third nymphal stage, the volume of the neuropil increases at a faster rate than the cortex. J. Morphol. 277:537–548, 2016. © 2016 Wiley Periodicals, Inc.     

Morphological patterns of the intraparietal sulcus and the anterior intermediate parietal sulcus of Jensen in the human brain

Distinct parts of the intraparietal sulcal cortex contribute to sensorimotor integration and visual spatial attentional processing. A detailed examination of the morphological relations of the different segments of the complex intraparietal sulcal region in the human brain in standard stereotaxic space, which is a prerequisite for detailed structure-to-function studies, is not available. This study examined the intraparietal sulcus (IPS) and the related sulcus of Jensen in magnetic resonance imaging brain volumes registered in the Montreal Neurological Institute stereotaxic space. It was demonstrated that the IPS is divided into two branches: the anterior ramus and the posterior ramus of the IPS, often separated by a submerged gyral passage. The sulcus of Jensen emerges between the anterior and posterior rami of the IPS, and its ventral end is positioned between the first and second caudal branches of the superior temporal sulcus. In a small number of brains, the sulcus of Jensen may merge superficially with the first caudal branch of the superior temporal sulcus. The above morphological findings are discussed in relation to previously reported functional neuroimaging findings and provide the basis for future exploration of structure-to-function relations in the posterior parietal region of individual subjects.     

Tail development and regeneration throughout the life cycle of the four-toed salamander Hemidactylium scutatum

The salamander tail displays different functions and morphologies in the aquatic and terrestrial stages of species with complex life cycles. During metamorphosis the function of the tail changes; the larval tail functions in aquatic locomotion while the juvenile and adult tail exhibits tail autotomy and fat storage functions. Because tail injury is common in the aquatic environment, we hypothesized that mechanisms have evolved to prevent altered larval tail morphology from affecting normal juvenile tail morphology. The hypothesis that injury to the larval tail would not affect juvenile tail morphology was investigated by comparing tail development and regeneration in Hemidactylium scutatum (Caudata: Plethodontidae). The experimental design included larvae with uninjured tails and with cut tails to simulate natural predation. The morphological variables analyzed to compare normally developing and regenerating tails were 1) tail length, 2) number of caudal vertebrae, and 3) vertebral centrum length. Control and experimental groups do not differ in time to metamorphosis or snout-vent length. Tails of experimental individuals are shorter than controls, yet they display a significantly higher rate of tail growth and less resorption of tail tissue. Anterior to the site of tail injury, caudal vertebrae in juveniles display greater average centrum lengths. Results suggest that regenerative mechanisms are functioning not only to produce structures, but also to influence growth of existing structures. Further investigation of juvenile and adult stages as well as comparative analyses of tail morphology in salamanders with complex life cycles will enhance our understanding of amphibian development and of the evolution of amphibian life cycles. J Morphol 233:15–29, 1997. © 1997 Wiley-Liss, Inc.     

Exoskeleton and Systematics: A Historical Problem in the Classification of Glyptodonts

The glyptodonts (Mammalia: Cingulata) are characterized by an exoskeleton comprising most notably an armored tail and an immobile dorsal carapace formed by a large number of osteoderms. In 1889, Florentino Ameghino published the first phylogenetic scenario for the glyptodonts, based on the sequential application of two transformation series related to the morphology of the tail armor and carapace osteoderms. From the early to mid 1900s, several authors used Ameghino’s transformation series subordinated to a model of evolution in which derived glyptodont groups had arisen independently from separate pre-middle Miocene ancestors. This approach, in which the morphological states of Ameghino’s series were considered analogous rather than homologous, provided different phylogenetic scenarios and the paraphyletic classification still in use. Two recent cladistic analyses based on cranial and postcranial (including caudal tube) characters support the monophyly of glyptodonts and suggest novel intra-clade relationships. However, neither analysis included the classic osteoderm characters used by earlier authors. Therefore, we propose new osteoderm and carapace characters and evaluate their performance in a new cladistic analysis. We found that: a) some osteoderm characters used by earlier authors to support ancestor-descendent hypotheses are in fact fully homoplastic autapomorphies (e.g., multiplication of the number of rows of peripheral figures); b) characters previously believed to have originated independently in several groups (e.g., presence of caudal tube) are synapomorphies at a wider hierarchical level; c) some ancestor–descendant pre-cladistic hypotheses are incompatible with the topology and synapomorphy distribution obtained; and d) there is no reason to favor exoskeletal characters in glyptodont systematics.     

Worms and gills,plates and spines: the evolutionary origins and incredible disparity of deuterostomes revealed by fossils,genes, and development

Deuterostomes are the major division of animal life which includes sea stars, acorn worms, and humans, among a wide variety of ecologically and morphologically disparate taxa. However, their early evolution is poorly understood, due in part to their disparity, which makes identifying commonalities difficult, as well as their relatively poor early fossil record. Here, we review the available morphological, palaeontological, developmental, and molecular data to establish a framework for exploring the origins of this important and enigmatic group. Recent fossil discoveries strongly support a vermiform ancestor to the group Hemichordata, and a fusiform active swimmer as ancestor to Chordata. The diverse and anatomically bewildering variety of forms among the early echinoderms show evidence of both bilateral and radial symmetry. We consider four characteristics most critical for understanding the form and function of the last common ancestor to Deuterostomia: Hox gene expression patterns, larval morphology, the capacity for biomineralization, and the morphology of the pharyngeal region. We posit a deuterostome last common ancestor with a similar antero-posterior gene regulatory system to that found in modern acorn worms and cephalochordates, a simple planktonic larval form, which was later elaborated in the ambulacrarian lineage, the ability to secrete calcium minerals in a limited fashion, and a pharyngeal respiratory region composed of simple pores. This animal was likely to be motile in adult form, as opposed to the sessile origins that have been historically suggested. Recent debates regarding deuterostome monophyly as well as the wide array of deuterostome-affiliated problematica further suggest the possibility that those features were not only present in the last common ancestor of Deuterostomia, but potentially in the ur-bilaterian. The morphology and development of the early deuterostomes, therefore, underpin some of the most significant questions in the study of metazoan evolution.     

A new species of Procolobomatus Castro Romero, 1994 (Copepoda: Philichthyidae) endoparasitic in a deepwater longtail red snapper (Actinopterygii: Lutjanidae) off Ishigaki Island, Japan, with records of philichthyid copepods reported from Asian waters

A new species of the Philichthyidae Vogt, 1877 (Copepoda: Poecilostomatoida), Procolobomatus hoi n. sp., is described based on adult female specimens recovered from the cephalic sensory canals of Etelis coruscans Valenciennes (Actinopterygii: Lutjanidae) caught off Ishigaki Island, the Ryukyu Islands, southern Japan. The new species differs from its congeners by having the following combination of characters: a long medial cephalic lobe about one-third the length of the body; an armature of five spines on the distal exopodal segment of leg 2; one long apical seta on the papillose leg 4; a caudal ramus armed with one medial and four terminal setae (two middle setae are inflated); and spinulose ornamentation covering the body. Procolobomatus hoi n. sp. is the first member of the genus reported from the western Pacific Ocean and from a host of the family Lutjanidae. Previous records of philichthyid copepods from Asian waters are also reported.     

A new lentic form of the “yoshinobori” species complex, Rhinogobius spp. from Lake Biwa, Japan, compared with lake–river migrating Rhinogobius sp. OR

 The various life history strategies seen within the “yoshinobori” species complex of the genus Rhinogobius, which differentiated from an amphidromous ancestor, have been grouped ecologically into amphidromous, fluvial, and lacustrine types. In the Lake Biwa water system, two lacustrine forms exist, a newly discovered, exclusively lentic form and the already well known Rhinogobius sp. OR, which generally undergoes lake–river migration but also includes lentic individuals that share spawning grounds with the former lentic form. Detailed morphological comparisons and allozyme analysis revealed consistently clear differences between the two forms, indicating them to be distinct species. The newly discovered lentic form has many distinctive morphological features that enable it to be distinguished from sympatric Rhinogobius sp. OR: dwarfness, short snout, longitudinally slender pelvic fin, undeveloped frenum with a low lamella, low first dorsal fin in adult males, lesser caudal peduncle depth, scaleless predorsal and ventral areas, and incomplete sensory canals. The lentic form was temporarily named Rhinogobius sp. BW. The life history patterns of the lake-inhabiting populations were separated into two categories: a lake–river migratory lifestyle and an exclusively lentic lifestyle.     

Phylogeny of the Plumularioidea (Hydrozoa, Leptothecata): evolution of colonial organisation and life cycle

The Plumularioidea (Cnidaria, Hydrozoa, Leptothecata) are the most species rich superfamily of the class Hydrozoa. They display a complex and diversified colonial organisation and their life cycle comprises either a reduced free-living, pelagic generation (medusoid), alternating with the benthic colonial form or in most species, no pelagic generation. In order to understand the evolution of colonial and life cycle characters among Plumularioidea, we have reconstructed their phylogeny. Partial mitochondrial 16S rRNA sequences and 64 morphological characters were analysed separately and in combination. The morphological data included not only characters of the individual polyps and medusae, but also characters describing the organisation of colonies, for which we propose general principles applying to character coding in modular organisms. The phylogenetic analyses supported the monophyly of Plumularioidea and of the four plumularioid families (Aglaopheniidae, Halopterididae, Kirchenpaueriidae and Plumulariidae). Most genera were paraphyletic or polyphyletic. This study highlights multiple morphological simplifications of the colonial organisation during the evolution of Plumularioidea and the convergence of the defensive polyps — the dactylozooids — of Plumularioidea with those of others Leptothecata ( Hydrodendron ) or Anthoathecata ( Hydractinia ). Concerning the evolution of the life cycle, the phylogeny supports a provocative scenario, where the medusa was lost in an ancestor of the Plumularioidea, and then re-acquired four times independently within this group, in the form of simple medusoids.     

Clarification of the host substrate of Ascopolyporus and description of Ascopolyporus philodendrus sp. nov

During a recent collection trip to Barro Colorado Island, Panama, two species belonging to genus Ascopolyporus (Clavicipitaceae, Hypocreales) were collected. Species of Ascopolyporus are epibionts of their bamboo (Poaceae) host and long thought to be biotrophs of their plant hosts. However, based on morphological observations and phylogenetic evidence using large subunit ribosomal DNA data, we propose that genus Ascopolyporus is likely composed of pathogens of scale insects (Coccoideae, Homoptera). Phylogenetic analyses included Ascopolyporus spp. in a clade containing only entomopathogenic clavicipitaceous species (100% posterior probability), and the scale insect pathogen Hyperdermium bertonii was found to share the most recent common ancestor with the Ascopolyporus clade (98% posterior probability). In addition remnants of the scale insect were observed to be embedded within stromata during early stages of stroma development. Ascopolyporus philodendrus sp. nov. was described and distinguished from the type species of the genus, A. polychrous, based on perithecial size, ascus size, plant host substrate and phylogenetic evidence. Furthermore subfamily Clavicipitoideae (Clavicipitaceae) was included and well supported in a single clade (100% posterior probability).     

The nature of the last universal ancestor and the root of the tree of life, still open questions.

The nature of the last universal ancestor to all extent cellular organisms and the rooting of the universal tree of life are fundamental questions which can now be addressed by molecular evolutionists. Several scenarios have been proposed during the last years, based on the phylogenies of ribosomal RNA and of duplicated proteins, which suggest that the last universal ancestor was either an RNA progenote or an hyperthermophilic prokaryote. We discuss these hypotheses in the light of new data on the evolution of DNA metabolizing enzymes and of contradictions between different protein phylogenies. We conclude that the last universal ancestor was a member of the DNA world already containing several DNA polymerases and DNA topoisomerases. Furthermore, we criticize current data which suggest that the rooting of the universal tree of life is located in the eubacterial branch and we conclude that both rooting the universal tree and the nature of the last universal ancestor are still open questions.     

Phylogeny and intraspecific variability of holoparasitic Orobanche (Orobanchaceae) inferred from plastid rbcL sequences

The rbcL sequences of 106 specimens representing 28 species of the four recognized sections of Orobanche were analyzed and compared. Most sequences represent pseudogenes with premature stop codons. This study confirms that the American lineage (sects. Gymnocaulis and Myzorrhiza) contains potentially functional rbcL-copies with intact open reading frames and low rates of non-synonymous substitutions. For the first time, this is also shown for a member of the Eurasian lineage, O. coerulescens of sect. Orobanche, while all other investigated species of sects. Orobanche and Trionychon contain pseudogenes with distorted reading frames and significantly higher rates of non-synonymous substitutions. Phylogenetic analyses of the rbcL sequences give equivocal results concerning the monophyly of Orobanche, and the American lineage might be more closely related to Boschniakia and Cistanche than to the other sections of Orobanche. Additionally, species of sect. Trionychon phylogenetically nest in sect. Orobanche. This is in concordance with results from other plastid markers (rps2 and matK), but in disagreement with other molecular (nuclear ITS), morphological, and karyological data. This might indicate that the ancestor of sect. Trionychon has captured the plastid genome, or parts of it, of a member of sect. Orobanche. Apart from the phylogenetically problematic position of sect. Trionychon, the phylogenetic relationships within sect. Orobanche are similar to those inferred from nuclear ITS data and are close to the traditional groupings traditionally recognized based on morphology. The intraspecific variation of rbcL is low and is neither correlated with intraspecific morphological variability nor with host range. Ancestral character reconstruction using parsimony suggests that the ancestor of O. sect. Orobanche had a narrow host range.     

中国东北马斯特里赫特阶的Wulagasaurus dongi(鸭嘴龙亚科)的重新评估与系统发育分析(英文)

通过对黑龙江省乌拉嘎地区晚白垩世渔亮子组地层发现的董氏乌拉嘎龙(Wulagasaurus dongi)的原有材料和新材料进行对比研究和重新评估,可以认定以前归入乌拉嘎龙的部分骨骼(包括不完整的脑颅骨、上颌骨和肩胛骨)实际上应该属于赖氏龙类,并相应地修订了其鉴定特征。乌拉嘎龙具有同北美地区发现的短冠龙和慈母龙十分相似的骨学特征:长而楔形的前顶点位于颧骨前支的一半背腹高度处;颧骨后支呈扇形;乌喙骨的腹突相对较长且纤细;肱骨三角胸嵴较不发育,适度地向前外方扩展;髂骨髋臼上突的腹缘呈不对称的U形,缺乏一条强烈的嵴连接其后部区域与髋臼后突的背缘。系统发育分析结果显示乌拉嘎龙、短冠龙和慈母龙共同构成了鸭嘴龙亚科的一个基干支系。该支系起源于桑托期的亚洲,可能在中坎帕期之前发生分异并通过白令陆桥向北美地区迁徙辐射。