scholarly journals Solution to the phylogenetic enigma of Tetraplatia , a worm-shaped cnidarian

2005 ◽  
Vol 2 (1) ◽  
pp. 120-124 ◽  
Author(s):  
Allen G Collins ◽  
Bastian Bentlage ◽  
George I Matsumoto ◽  
Steven H.D Haddock ◽  
Karen J Osborn ◽  
...  
Keyword(s):  
Body Plan ◽  
Phylogenetic Position ◽  
Recent Origin ◽  
Phylogenetic Affinities

Tetraplatia is a genus containing two species of pelagic cnidarians of curious morphology. Their vermiform shape and four swimming flaps are difficult to relate to the features of other cnidarians, thus obscuring their phylogenetic affinities. Since their discovery in the mid-1800s, a number of prominent cnidarian workers have weighed in on this conundrum, some arguing that they are aberrant hydrozoans and others concluding that they are unusual scyphozoans. Current taxonomic practice conforms to the latter view. However, data presented here from the large and small subunits of the nuclear ribosome leave little doubt that Tetraplatia is in fact a hydrozoan genus. Indeed, its precise phylogenetic position is within Narcomedusae, as some authors had previously deduced based on structural characters. The distinctive body plan of Tetraplatia is remarkable because it appears to have a recent origin, in contrast to the prevailing pattern of metazoan history.

scholarly journals OnProphocaandLeptophoca(Pinnipedia, Phocidae) from the Miocene of the North Atlantic realm: redescription, phylogenetic affinities and paleobiogeographic implications

PeerJ ◽  
2017 ◽  
Vol 5 ◽  
pp. e3024 ◽  
Author(s):  
Leonard Dewaele ◽  
Olivier Lambert ◽  
Stephen Louwye
Keyword(s):  
North America ◽  
Middle Miocene ◽  
New Combination ◽  
Phylogenetic Position ◽  
Appendicular Skeleton ◽  
Original Diagnosis ◽  
Sediment Samples ◽  
The North ◽  
The North Sea ◽  
Phylogenetic Affinities

BackgroundProphocaandLeptophocarepresent the oldest known genera of phocine seals, dating from the latest early to middle Miocene. Originally,Prophoca rousseauiandProphoca proximawere described based on fragmentary remains from the Miocene of Belgium. However, several researchers contested the union ofProphoca rousseauiandProphoca proximainto one genus, without providing evidence. The stratigraphic context ofProphocaremained poorly constrained due to the lack of precise data associated with the original specimens collected in the area of Antwerp (north of Belgium).MethodsProphocaandLeptophocaare redescribed and their phylogenetic position among Phocidae is reassessed using PAUP. Dinoflagellate biostratigraphy has been carried out on sediment samples associated with specimens fromProphocaandLeptophocato elucidate their approximate ages.ResultsWhereas the speciesProphoca rousseauiis redescribed,Prophoca proximais considered synonymous toLeptophoca lenis, with the proposal of a new combinationLeptophoca proxima(Van Beneden, 1877). Sediment samples from specimens of both taxa have been dated to the late Langhian–early Serravallian (middle Miocene). Following a reinvestigation ofLeptophoca amphiatlantica, characters from the original diagnosis are questioned and the specimens ofLeptophoca amphiatlanticaare consideredLeptophocacf.L. proxima. In a phylogenetic analysis,Prophoca rousseauiandLeptophoca proximaconstitute early branching stem-phocines.DiscussionLeptophoca proximafrom the North Sea Basin is younger than the oldest known find ofLeptophoca proximafrom North America, which does not contradict the hypothesis that Phocinae originated along the east coast of North America during the late early Miocene, followed by dispersal to Europe shortly after. Morphological features of the appendicular skeleton indicate thatProphoca rousseauiandLeptophoca proximahave archaic locomotory modes, retaining a more prominent use of the fore flipper for aquatic propulsion than extant Phocidae.

scholarly journals Naked chancelloriids from the lower Cambrian of China show evidence for sponge-type growth

2018 ◽  
Vol 285 (1881) ◽  
pp. 20180296 ◽  
Author(s):  
Pei-Yun Cong ◽  
Thomas H. P. Harvey ◽  
Mark Williams ◽  
David J. Siveter ◽  
Derek J. Siveter ◽  
...  
Keyword(s):  
Lower Cambrian ◽  
Body Cavity ◽  
Body Plan ◽  
The Body ◽  
Phylogenetic Position ◽  
Axis Formation ◽  
Large Size ◽  
Show Evidence ◽  
Body Plan Evolution ◽  
Extinct Group

Chancelloriids are an extinct group of spiny Cambrian animals of uncertain phylogenetic position. Despite their sponge-like body plan, their spines are unlike modern sponge spicules, but share several features with the sclerites of certain Cambrian bilaterians, notably halkieriids. However, a proposed homology of these ‘coelosclerites' implies complex transitions in body plan evolution. A new species of chancelloriid, Allonnia nuda , from the lower Cambrian (Stage 3) Chengjiang Lagerstätte is distinguished by its large size and sparse spination, with modified apical sclerites surrounding an opening into the body cavity. The sclerite arrangement in A. nuda and certain other chancelloriids indicates that growth involved sclerite addition in a subapical region, thus maintaining distinct zones of body sclerites and apical sclerites. This pattern is not seen in halkieriids, but occurs in some modern calcarean sponges. With scleritome assembly consistent with a sponge affinity, and in the absence of cnidarian- or bilaterian-grade features, it is possible to interpret chancelloriids as sponges with an unusually robust outer epithelium, strict developmental control of body axis formation, distinctive spicule-like structures and, by implication, minute ostia too small to be resolved in fossils. In this light, chancelloriids may contribute to the emerging picture of high disparity among early sponges.

scholarly journals The double odyssey of Madagascan polystome flatworms leads to new insights on the origins of their amphibian hosts

2009 ◽  
Vol 276 (1662) ◽  
pp. 1575-1583 ◽  
Author(s):  
Olivier Verneau ◽  
Louis H Du Preez ◽  
Véronique Laurent ◽  
Liliane Raharivololoniaina ◽  
Frank Glaw ◽  
...  
Keyword(s):  
Molecular Dating ◽  
Phylogenetic Position ◽  
Late Mesozoic ◽  
Biogeographic History ◽  
On This Island ◽  
The Family ◽  
Molecular Phylogenetic ◽  
History Of ◽  
Recent Origin ◽  
High Species Richness

Polystomatid flatworms are parasites of high host specificity, which mainly infect amphibian hosts. Only one polystome species has so far been recorded from Madagascar despite the high species richness and endemicity of amphibians on this island. Out of the 86 screened Malagasy frog species, we recovered polystomes from 25 in the families Ptychadenidae and Mantellidae. Molecular phylogenetic analysis uncovered an unexpected diversity of polystome species belonging to two separate clades: one forming a lineage within the genus Metapolystoma , with one species in Ptychadena and several species in the mantellid host genera Aglyptodactylus and Boophis ; and the second corresponding to an undescribed genus that was found in the species of the subfamily Mantellinae in the family Mantellidae. The phylogenetic position of the undescribed genus along with molecular dating suggests that it may have colonized Madagascar in the Late Mesozoic or Early Cainozoic. By contrast, the more recent origin of Metapolystoma in Madagascar at ca 14–2 Myr ago strongly suggests that the ancestors of Ptychadena mascareniensis colonized Madagascar naturally by overseas dispersal, carrying their Metapolystoma parasites. Our findings provide a striking example of how parasite data can supply novel insights into the biogeographic history of their hosts.

scholarly journals Hex Hox: De Novo Transcriptome Assembly and Embryonic Hox Gene Expression in the Burrowing Mayfly Hexagenia Limbata (Ephemeridae)

2021 ◽  
Author(s):  
Christopher J Gonzalez ◽  
Tobias R Hildebrandt ◽  
Brigid C O'Donnell
Keyword(s):  
Hox Genes ◽  
Transcriptome Assembly ◽  
Expression Profiles ◽  
Expression Patterns ◽  
Body Plan ◽  
The Body ◽  
Phylogenetic Position ◽  
Developmental Genetics ◽  
Early Instar ◽  
Hexagenia Limbata

Abstract Background: Hox genes are key regulators of appendage development in the insect body plan. The body plan of Mayfly (Ephemeroptera) nymphs differs due to the presence of evolutionarily significant abdominal appendages called gills. Despite mayflies’ basal phylogenetic position and novel morphology amongst insects, little is known of their developmental genetics. Here we present an annotated transcriptome for the mayfly Hexagenia limbata, with annotated sequences for putative Hox peptides and embryonic expression profiles for the Hox genes Antp and Ubx/abd-A. Results: Transcriptomic sequencing of early instar H. limbata nymphs yielded a high-quality assembly of 83,795 contigs, of which 22,975 were annotated against Folsomia candida, Nilaparvata lugens, Zootermopsis nevadensis and UniRef90 protein databases. Peptide annotations included eight of the ten canonical Hox genes (lab, pb, Dfd, Scr, Antp, Ubx, abd-A and Abd-B), most of which contained all functional domains and motifs conserved in insects. Expression patterns of Antp and Ubx/abd-A in H. limbata were visualized from early to late embryogenesis, and are also highly conserved with patterns reported for other non-holometabolous insects.Conclusions: We present evidence that both H. limbata Hox peptide sequences and embryonic expression patterns for Antp and Ubx/abd-A are extensively conserved with other insects. These findings suggest mayfly Antp and Ubx/abd-A play similar appendage promoting and repressing roles in the thorax and abdomen, respectively. The identified expression of Ubx and abd-A in early instar nymphs further suggests that mayfly gill development is not subject to Ubx or abd-A repression. Previous studies have shown that insect Ubx and abd-A repress appendages by inhibiting their distal structures, which can permit the development of proximal appendage types. In line with past morphology-based work, we propose that mayfly gills are proximal appendage structures, possibly homologous to the proximal appendage structures of crustaceans.

Exploring the myriapod body plan: expression patterns of the ten Hox genes in a centipede

Development ◽  
2002 ◽  
Vol 129 (5) ◽  
pp. 1225-1238 ◽  
Author(s):  
Cynthia L. Hughes ◽  
Thomas C. Kaufman
Keyword(s):  
Gene Expression ◽  
Hox Genes ◽  
Expression Patterns ◽  
Body Plan ◽  
Phylogenetic Position ◽  
The Novel ◽  
Fushi Tarazu ◽  
Hox Gene ◽  
Insight Into ◽  
Gaining Insight

The diversity of the arthropod body plan has long been a fascinating subject of study. A flurry of recent research has analyzed Hox gene expression in various arthropod groups, with hopes of gaining insight into the mechanisms that underlie their evolution. The Hox genes have been analyzed in insects, crustaceans and chelicerates. However, the expression patterns of the Hox genes have not yet been comprehensively analyzed in a myriapod. We present the expression patterns of the ten Hox genes in a centipede, Lithobius atkinsoni, and compare our results to those from studies in other arthropods. We have three major findings. First, we find that Hox gene expression is remarkably dynamic across the arthropods. The expression patterns of the Hox genes in the centipede are in many cases intermediate between those of the chelicerates and those of the insects and crustaceans, consistent with the proposed intermediate phylogenetic position of the Myriapoda. Second, we found two ‘extra’ Hox genes in the centipede compared with those in Drosophila. Based on its pattern of expression, Hox3 appears to have a typical Hox-like role in the centipede, suggesting that the novel functions of the Hox3 homologs zen and bicoid were adopted somewhere in the crustacean-insect clade. In the centipede, the expression of the gene fushi tarazu suggests that it has both a Hox-like role (as in the mite), as well as a role in segmentation (as in insects). This suggests that this dramatic change in function was achieved via a multifunctional intermediate, a condition maintained in the centipede. Last, we found that Hox expression correlates with tagmatic boundaries, consistent with the theory that changes in Hox genes had a major role in evolution of the arthropod body plan.

scholarly journals Integrative Taxonomic, Ecological and Genotyping Study of Charophyte Populations from the Egyptian Western-Desert Oases and Sinai Peninsula

Plants ◽  
2021 ◽  
Vol 10 (6) ◽  
pp. 1157
Author(s):  
Abdullah A. Saber ◽  
Andrey A. Gontcharov ◽  
Arthur Yu. Nikulin ◽  
Vyacheslav Yu. Nikulin ◽  
Walaa A. Rayan ◽  
...  
Keyword(s):  
North Africa ◽  
Phylogenetic Analyses ◽  
Research Work ◽  
Western Desert ◽  
Freshwater Wetland ◽  
Phylogenetic Position ◽  
Sinai Peninsula ◽  
Algal Group ◽  
Integrative Study ◽  
Phylogenetic Affinities

Present-day information available on the charophyte macroalgae in Egypt, including their phylogenetic affinities, remains largely incomplete. In this study, nine charophyte populations were collected from different aquatic biotopes across the Egyptian Western-Desert Oases and Sinai Peninsula. All populations were investigated using an integrative polyphasic approach including phylogenetic analyses inferred from the chloroplast-encoded gene (rbcL) and the internal transcribed spacer (ITS1) regions, in parallel with morphotaxonomic assignment, ultrastructure of the oospore walls, and autecology. The specimens identified belonged to the genera Chara, Nitella, and Tolypella, with predominance of the first genus to which five species were assigned though they presented some interesting aberrant taxonomic features: C. aspera, C. contraria, C. globata, C. tomentosa, and C. vulgaris. Based on our integrative study, the globally rare species C. globata was reported for the second time for the whole African continent. The genus Nitella was only represented by N. flagellifera, and based on the available literature, it is a new record for North Africa. Noteworthy, an interesting Tolypella sp., morphologically very similar to T. glomerata, was collected and characterized and finally designated with the working name ‘Tolypella sp. PBA–1704 from a desert, freshwater wetland’, mainly based on its concatenated rbcL+ITS1 phylogenetic position. This study not only improved our understanding on the diversity, biogeography and autecological preferences of charophytes in Egypt, but it also broadened our knowledge on this vulnerable algal group in North Africa, emphasizing the need of more in-depth research work in the future, particularly in the less–impacted desert habitats.

scholarly journals Ancyrocephalidae (Monogenea) of Lake Tanganyika: Does the Cichlidogyrus parasite fauna of Interochromis loocki (Teleostei, Cichlidae) reflect its host’s phylogenetic affinities?

2015 ◽  
Vol 84 (1) ◽  
pp. 25-38 ◽  
Author(s):  
Antoine Pariselle ◽  
Maarten Van Steenberge ◽  
Jos Snoeks ◽  
Filip A.M. Volckaert ◽  
Tine Huyse ◽  
...  
Keyword(s):  
Lake Tanganyika ◽  
Habitat Choice ◽  
Parasite Fauna ◽  
Phylogenetic Position ◽  
Monogenean Parasite ◽  
Tanganyikan Cichlid ◽  
Faunal Diversity ◽  
Phylogenetic Affinities ◽  
Attachment Organ ◽  
Species Flocks

The faunal diversity of Lake Tanganyika, with its fish species flocks and its importance as a cradle and reservoir of ancient fish lineages seeding other radiations, has generated a considerable scientific interest in the fields of evolution and biodiversity. The Tropheini, an endemic Tanganyikan cichlid tribe, fills a peculiar phylogenetic position, being closely related to the haplochromine radiations of Lakes Malawi and Victoria. Several problems remain regarding their genus-level classification. For example, the monotypic genus Interochromis is phylogenetically nested within Petrochromis; its only representative, I. loocki, has often been reclassified. As monogenean flatworms are useful markers for fish phylogeny and taxonomy, the monogenean fauna of Interochromis loocki was examined and compared to that of other tropheine cichlids. Three new monogenean species belonging to Cichlidogyrus are described from Interochromis loocki: Cichlidogyrus buescheri Pariselle and Vanhove, sp. nov., Cichlidogyrus schreyenbrichardorum Pariselle and Vanhove, sp. nov. and Cichlidogyrus vealli Pariselle and Vanhove, sp. nov. Their haptoral anchors remind more of congeners infecting species of Petrochromis than of all Cichlidogyrus spp. hitherto described from other tropheine cichlids. Attachment organ morphology has been proven to mirror the phylogenetic affinities of Cichlidogyrus lineages. Therefore the monogenean parasite fauna of I. loocki reflects this host’s position within Petrochromis. Moreover, I. loocki differs in habitat choice from Petrochromis spp. This study hence confirms that host range and host-specificity in Cichlidogyrus spp. parasitizing tropheines is determined by the host’s phylogenetic position, rather than by a shared ecological niche.

New species of Moluccan trichaline net-winged beetles, with remarks on the phylogenetic position and distribution of Schizotrichalus (Coleoptera: Lycidae: Metriorrhynchinae)

Zootaxa ◽  
2019 ◽  
Vol 4623 (2) ◽  
pp. 341-350 ◽  
Author(s):  
MATEJ BOCEK ◽  
KRISTYNA ADAMKOVA
Keyword(s):  
New Species ◽  
Dna Sequences ◽  
Morphological Traits ◽  
New Guinea ◽  
Molecular Data ◽  
Phylogenetic Position ◽  
General Validity ◽  
Ancestral Area ◽  
Recent Origin ◽  
Sister Relationships

The Moluccan net-winged beetle fauna remains poorly studied and here, new species of Schizotrichalus Kleine, 1926 and Eniclases Waterhouse, 1879 are reported from Halmahera. Using morphological traits and cox1 mitochondrial DNA sequences, we propose two new species, Eniclases kusyi sp. nov. and Schizotrichalus halmaherensis sp. nov., and redescribe E. moluccanus Kleine, 1930. New molecular data confirm morphology-based sister relationships between Schizotrichalus and Eniclases and the analysis identifies the combined area of the present-day Halmahera and New Guinea as an ancestral area of these genera. Now, Halmahera and New Guinea are quite similar in respect of the number of trichaline genera. Concerning the size of islands and the recent origin of the nowadays northern Moluccas, these results are unexpected and thus the general validity of this distribution pattern should be confirmed with other groups of beetles. 

scholarly journals Halszkaraptor escuilliei and the evolution of the paravian bauplan

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Chase D. Brownstein
Keyword(s):  
Center Of Mass ◽  
Body Plan ◽  
Early Evolution ◽  
The Body ◽  
Phylogenetic Position ◽  
Sister Clade ◽  
Environmental Setting ◽  
Evolution Of Birds

Abstract The evolution of birds from dinosaurs is a subject that has received great attention among vertebrate paleontologists. Nevertheless, the early evolution of the paravians, the group that contains birds and their closest non-avian dinosaur relatives, remains very poorly known. Even the most basal members of one paravian lineage, the Dromaeosauridae, already show a body plan that differs substantially from their closest non-paravian relatives. Recently, the dromaeosaurid Halszkaraptor escuilliei was described from the Cretaceous of Mongolia. Halszkaraptor possesses numerous unserrated premaxillary teeth, a platyrostral rostrum with a developed neurovascular system, an elongate neck, bizarrely-proportioned forearms, and a foreword-shifted center of mass, differing markedly from other paravians. A reevaluation of the anatomy, taphonomy, environmental setting, and phylogenetic position of H. escuilliei based on additional comparisons with other maniraptorans suggests that, rather than indicating it was a semiaquatic piscivore, the body plan of this dinosaur bears features widely distributed among maniraptorans and in some cases intermediate between the conditions in dromaeosaurids and related clades. I find no evidence for a semiaquatic lifestyle in Halszkaraptor. A phylogenetic reevaluation of Halszkaraptorinae places it as the sister clade to Unenlagiinae, indicating the bizarre features of unenlagiines previously interpreted as evidence of piscivory may also represent a mosaic of plesiomorphic, derived, and intermediate features. The anatomy of Halszkaraptor reveals that dromaeosaurids still possessed many features found in more basal maniraptoran and coelurosaur clades, including some that may have been tied to herbivory. Rather than being a semiaquatic piscavore, Halszkaraptor was a basal dromaeosaurid showing transitional features.

REVISION OF NEARCTIC SPECIES OF ACTIA ROBINEAU-DESVOIDY (DIPTERA: TACHINIDAE)

1991 ◽  
Vol 123 (4) ◽  
pp. 745-776 ◽  
Author(s):  
James E. O’Hara
Keyword(s):  
Type Locality ◽  
Species Pair ◽  
North West ◽  
Neotropical Species ◽  
Palearctic Species ◽  
Recent Origin ◽  
Species Groups ◽  
North West Territories ◽  
Phylogenetic Affinities ◽  
Nearctic Region

AbstractEight species of the siphonine genus Actia Robineau-Desvoidy are recognized in the Nearctic Region, including four that are new: A. dasymyia sp.nov. (type-locality 21 mi. east Tuktoyaktuk, North West Territories, Canada), A. dimorpha sp.nov. (type-locality Sapelo Island, Georgia, USA), A. radialis sp.nov. (type-locality Gatineau Park, Quebec, Canada), and A. sternalis sp.nov. (type-locality mi. 51 Dempster Highway, Yukon, Canada). Adults of the eight species are keyed, described, illustrated (heads, wings, and male terminalia), and their distributions mapped. The species are arranged into three species groups: the autumnalis-group with Nearctic members A. autumnalis (Townsend), A. rufescens (Greene), A. diffidens Curran, and A. dimorpha sp.nov.; the lamia-group with Nearctic members A. interrupta Curran, A. dasymyia sp.nov., and A. radialis sp.nov.; and the crassicornis-group with the single Nearctic member A. sternalis sp.nov. Nearctic Actia are inferred to be of relatively recent origin because only the A. autumnalis/A. rufescens species pair seems to have speciated within the Nearctic Region. Actia autumnalis/A. rufescens, A. diffidens, and A. dimorpha are each hypothesized to have their closest phylogenetic affinities with Neotropical species, and A. sternalis, A. interrupta, A. dasymyia, and questionably A. radialis are each hypothesized to have their closest affinities with Palearctic species.

Sign in / Sign up

Export Citation Format

Share Document