Ventral Depression Research Articles

A Unique and Species-Rich Assemblage of Freshwater Glassfishes (Teleostei: Ambassidae: Dapalis) from the lower Oligocene of the Central Paratethys with the Description of Four New Species

We describe four new species of the fossil genus Dapalis (Ambassidae), Dapalis absconditus sp. nov., Dapalis octospinus sp. nov., Dapalis parvus sp. nov. and Dapalis quintus sp. nov., based on articulated skeletons with otoliths in situ from a freshwater habitat of the lower Oligocene of Raljin/Strelac (Serbia). Besides in body shape (e.g., body length, body depth, head length, preanal length), the species differ in morphological characters like, e.g., the serration of the preopercle, the length of the first two spines of the first dorsal and the anal fin and the morphology of the sagittal otoliths (e.g., ratio of otolith height to otolith length, ratio of otolith width to otolith length). Together with D. pauciserratus, also described from Raljin, these four species represent the most species-rich assemblage of freshwater Dapalis known so far. The compartmentalization of the internal structure of the spines reveals the close relationship of Dapalis and extant Ambassidae. Additionally, we discuss a new character from the ventral field of the otolith, a ventral depression, only found in species from Raljin. This new character is unique among the European Dapalis species and allows us to separate these five species into two species groups.

First report of toxigenic Amphidoma languida (Amphidomataceae, Dinophyceae) from the Pacific, with reference to intracellular ultrastructure and azaspiracid compounds

SUMMARYMorphology, phylogeny and azaspiracid (AZA) production of a strain of Amphidoma languida isolated from the subtropical Mexican Pacific were examined. Scanning electron microscopy showed the thecal plate arrangement of Am. languida from Mexico as Po, cp, X, 6′, 6′′, 6C, 5S, 6′′′, 2′′′′, with the prominent apical pore complex, the ventral pore on the anterior of the 1′ plate near the suture to the 6′ plate, and the antapical pore on the 2′′′′ plate, which are congruent with those of Am. languida reported from the Atlantic. The ventral depression was occasionally observed on the anterior end of Sa plate. Cells had a dinokaryotic nucleus positioned in the posterior part of the cell and parietal yellowish chloroplasts with a spherical pyrenoid in the episome. Transmission electron microscopy showed crystalline vesicles and tubular cytoplasmic invaginations in the pyrenoid, which resembled those reported from the most related non‐toxigenic species Amphidoma fulgens. The intracellular components, different from Am. fulgens, were oil droplets and lipid‐associated membranous structures. AZA‐2 was detected from the strain by liquid chromatography‐tandem mass spectrometry with a cell quota of 30.9 fg cell−1. Three other AZA‐related compounds were also detected. This is the first report of AZA‐producing Am. languida in the Pacific Ocean.

Phylogeny and ultrastructure of a non-toxigenic dinoflagellate Amphidoma fulgens sp. nov. (Amphidomataceae, Dinophyceae), with a wide distribution across Asian Pacific

Amphidoma languida, a marine thecate dinoflagellate that produces the lipophilic toxin azaspiracids (AZAs), is primarily found in the Atlantic. Although this species has not been recorded in the Asian Pacific, environmental DNAs related to Am. languida have been widely detected in the region by metabarcoding analysis. Their morphology and AZA production remain unclear. In this study, the morphology, ultrastructure, phylogeny, and AZA production of nine Amphidoma strains isolated from Japan, Malaysia, and Philippines were investigated. Phylogenetic trees inferred from rDNAs (SSU, ITS, and LSU rDNA) showed monophyly of the nine Pacific strains and were sister to the Am. languida clade, including the toxigenic strains from the Atlantic. Cells were ellipsoid, 8.7–16.7 µm in length and 7.4–14.0 µm in width, with a conspicuous apical pore complex. A large nucleus in the hyposome, parietal chloroplast with a spherical pyrenoid in the episome, and refractile bodies were observed. Thecal tabulation was typical of Amphidoma, Po, cp, X, 6ʹ, 6ʹʹ, 6C, 5S, 6ʹʹʹ, 2ʹʹʹʹ. A ventral pore was located on the anterior of 1ʹ plate, beside the suture to 6ʹ plate. The presence of a ventral depression, on the anterior of anterior sulcal plate, was different from Am. languida. A large antapical pore, containing approximately 10 small pores, was observed. Cells were apparently smaller than Am. trioculata, a species possessing three pores (ventral pore, ventral depression, and antapical pore). TEM showed the presence of crystalline structures, resembling guanine crystals, and cytoplasmic invaginations into the pyrenoid matrix. Flagellar apparatus lacking the striated root connective is similar to peridinioids and related dinoflagellates. AZAs were not detected from the Pacific strains by LC-MS/MS. This non-toxigenic Amphidoma species, here we propose as Amphidoma fulgens sp. nov., is widely distributed in the Asian Pacific. Moreover, molecular comparison also suggested that most of the environmental DNA sequences previously reported as Am. languida or related sequences from the Asian Pacific were attributable to Am. fulgens.

The last of them? A new relic karaurid stem salamander from the Lower Cretaceous of Western Siberia, Russia

A new karaurid stem salamander, Kuzbassia sola gen. et sp. nov., from the Lower Cretaceous (Aptian) Ilek Formation of Shestakovo 1 locality in Western Siberia, Russia, is described on the basis of isolated vertebrae, including incomplete atlantal and trunk vertebral centra. The new taxon is diagnosed by the following unique combination of vertebral characters: the presence of a shallow dorsolateral depression and low ridges (longitudinal, vertical and oblique ridges) flanking this depression on the lateral surface of the atlantal centrum; the absence of deep lateral grooves or depressions on the lateral surfaces and ventral depression on the ventral surface of the atlantal centrum; the absence of ventro-lateral ridges, transverse processes and alar processes associated with the transverse processes on the atlantal centrum; anterior cotyles with elliptical anterior outline, located at an angle of approximately 150–160 degrees to each other; and the presence of a pair of rugose surfaces with low tubercles (= ?anterior basapophyses) on the ventral surface of the anterior portion of the trunk vertebral centrum. Kuzbassia sola gen. et sp. nov. is the last karaurid salamander in the fossil record to date.

On the stream-dwelling Crossodactylus timbuhy (Anura, Hylodidae): taxonomy, natural history, and geographic distribution.

The genus Crossodactylus has taxonomic problems due to the difficulty in properly identifying some populations to the species level. The deficient species diagnosis rises mostly due to high intraspecific variation and lack of information on topotypes. Crossodactylus timbuhy was described based only on external morphology of preserved adult specimens. Based on topotypic specimens, we provide further information on C. timbuhy regarding color in life (both adult and larvae), tadpole external morphology, vocal repertoire, natural history, and geographic distribution. The species identification was confirmed through comparison to the type series, 16S rRNA analysis, and bioacoustics. Crossodactylus timbuhy vocalizes during daylight along shallow slow-flowing streams. The advertisement call has ascendant amplitude modulation, duration of 2.18.4 s, 2375 pulsed notes, and peak frequency of 3.64.8 kHz. Our report on male unilateral sac inflation is the first within Crossodactylus. Although overall tadpole external morphology and coloration resemble other species of hylodids, we report ventral depression and golden iridophores also for the first time within Crossodactylus. Adult males display five antipredator mechanisms (interrupt calling, escape, aggression, posture, and aposematism). Finally, we restrict its geographic distribution to the Municipality of Santa Teresa, State of Esprito Santo, Southeastern Brazil.

<p class="Body">Erythraeid larvae parasitizing dragonflies in Zambia—description of Leptus (Leptus) chingombensis sp. nov. with data on biology and ecology of host-parasite interactions

A survey of odonate fauna in Zambia (Central Province, Luano District) resulted in discovery of ectoparasitic larvae of Leptus (L.) chingombensis sp. nov. (Trombidiformes: Parasitengona, Erythraeidae) on four species of dragonflies (Odonata) representing four different families assigned to Zygoptera and Anisoptera. The morphological characteristics of the new species is supported with DNA barcode sequence. Despite some intra-group variation related to relatively large sample, the morphological and genetic consistence confirm the common specific identity of the material. A brief comparison of Leptus spp. hitherto known from the Afrotropic as larvae is given. Supplementary data to the descriptions of Leptus (L.) bicristatus Fain et Elsen, 1987, Leptus (L.) aldonae Haitlinger, 1987 and Leptus (L.) soddagus Haitlinger, 1990, based on examination of type material, are provided. In the case of L. (L.) chingombensis sp. nov., the parasite load reached high, previously not recorded for Odonata–terrestrial Parasitengona association values, attaining at 44 and 49 larvae. Clear topic preferences towards the ventral side of the host’s body were recorded, with an additional tendency to distal parts of synthorax and the ventral depression of the abdomen. We hypothesize that the infestation did not take place synchronously at dragonflies emergence, but consisted in repeated infestation events during the recurrent appearance of dragonflies in the contact microhabitat occupied by Leptus. The very local character of the finding along with the regular appearance of larvae parasitizing dragonflies, obviously favoured by specific habitat conditions, no doubts confirms the non-accidental nature of the phenomenon.

On the larva and the zooid of the pterobranch Rhabdopleura recondita Beli, Cameron and Piraino, 2018 (Hemichordata, Graptolithina)

Hemichordates (Enteropneusta and Pterobranchia) belong to a small deuterostome invertebrate group that may offer insights on the origin and evolution of the chordate nervous system. Among them, the colonial pterobranch Rhabdopleuridae are recognized as living representatives of Graptolithina, a taxon with a rich fossil record. New information is provided here on the substrate selection and the life cycle of Rhabdopleura recondita Beli, Cameron and Piraino, 2018, and for the first time, we describe the nervous system organization of the larva and the adult zooid, as well as the morphological, neuroanatomical and behavioural changes occurring throughout metamorphosis. Immunohistochemical analyses disclosed a centralized nervous system in the sessile adult zooid, characterized by different neuronal subsets with three distinct neurotransmitters, i.e. serotonin, dopamine and RFamide. The peripheral nervous system comprises GABA-, serotonin-, and dopamine-immunoreactive cells. These observations support and integrate previous neuroanatomical findings on the pterobranch zooid of Cephalodiscus gracilis. Indeed, this is the first evidence of dopamine, RFamide and GABA neurotransmitters in hemichordates pterobranchs. In contrast, the lecithotrophic larva is characterized by a diffuse basiepidermal plexus of GABAergic cells, coupled with a small group of serotonin-immunoreactive cells localized in the characteristic ventral depression. It is envisaged the use of R. recondita as a novel and easily accessible hemichordate model organism to shed light on the evolution of hemichordates and more generally on the origin of deuterostome developmental mechanisms.

Electron microscopy of a 1991 spring plankton sample from the Argentinean Shelf reveals the presence of four new species of the Amphidomataceae (Dinophyceae)

SUMMARYThe dinophycean family Amphidomataceae encompasses the genera Azadinium and Amphidoma, which attract considerable attention because of their production potential for azaspiracids, i.e. lipophilic polyether phycotoxins. Many new species of Amphidomataceae were described in the last decade, but the diversity probably is not fully explored yet. In a continuation of a previous study, Amphidomatacean diversity of the 1991 spring plankton bloom along the Argentinean shelf was investigated. Based on morphology as inferred from scanning electron microscopy, three new species of Amphidoma and one new Azadinium are described. Azadinium asperum sp. nov. differed in size and shape from other Azadinium and had a characteristically rough and slightly granular surface of thecal plates. Amphidoma trioculata sp. nov. and Amphidoma cyclops sp. nov. differed by shape from most other Amphidoma, and can be differentiated from one another by the presence/absence of a antapical pore and by the size of a ventral depression. Amphidoma alata sp. nov. was unique by a conspicuous wing‐like sulcal list. Calculations based on the total number of small dinoflagellates and on relative scanning electron microscopy quantification indicated that density of all four species was fairly high (7–40 × 103 cells L−1), so a large number of cells could be investigated in the sample. A few more single cells in the sample are attributable to Amphidomataceae but do not belong to one of the described species. This indicates that the diversity of the group is still not fully explored.

Bysmatrum austrafrum sp. nov. (Dinophyceae), a novel tidal pool dinoflagellate from South Africa

:A new species of the dinoflagellate genus Bysmatrum was isolated from tidal pool samples originating from Cape Peninsula, South Africa. This new species was investigated by light, scanning and transmission electron microscopy, and its phylogenetic affinities were analyzed using molecular data. Cells were pentagonal in ventral view, 25–45 μm long and 20–42.5 μm wide and only slightly flattened in a dorsiventral plane. The epitheca, in apical view, was almost circular, with a slight ventral depression. Plate tabulation (PO, X, 4′, 3a, 7″, 6c, 4s, 5′′′, 2′′′′) was typical for the genus Bysmatrum. Apical plate 1′ was heptagonal and broadly asymmetric, with an elongated, fingerlike extension at the base. The intercalary plates 2a and 3a were separated by a direct connection between plates 3′ and 4″. The thecal plates were perforated by pores of different sizes and ornamented with linearly arranged reticulations. Intercalary bands were smooth, and antapical plates were not indented. This new species differs from the five other known species of the genus Bysmatrum in morphology (e.g. the shape of apical plate 1′) and it occupies an isolated position in phylogenetic trees inferred by analyses of small-subunit ribosomal DNA (SSU-rDNA) sequence data. This also represents the first report of the SSU rDNA sequence for Bysmatrum arenicola.

Molecular and morphological evidence for a new genus of small trapdoor spiders from arid Western Australia (Araneae : Mygalomorphae : Nemesiidae : Anaminae)

The trapdoor spider family Nemesiidae comprises 14 genera in Australia, the majority of which are included in the subfamily Anaminae. Here we provide evidence from a multigene molecular analysis of most Australian genera of Anaminae for a previously unrecognised clade that also differs from its sister-genus, Aname L. Koch, by the lack of a prominent asetose ventral depression on the pedipalpal tibia and the medium-sized mating spur on tibia I of males. This depression is a characteristic of all species of Aname examined to date, and represents a newly recognised character system in the subfamily. The new genus, named Hesperonatalius, is represented by three new species – H. maxwelli, sp. nov., H. harrietae, sp. nov. and H. langlandsi, sp. nov. – all from arid Western Australia. http://zoobank.org/References/D5352390-5D21-49DD-A123-A074422EB860

Ultrastructure of Sensilla on Larvae and Adults ofChrysomya megacephala(Diptera: Calliphoridae)

ABSTRACT: Sensilla on insect body parts play an important role on their behavior for ovipositing and foraging. To describe the morphology and distribution of sensilla on adults and larvae of C. megacephala, scanning electron miscroscopy was applied to give detailed information. There are five types of sensilla on antenna, three on the proboscis and ovipositor, two on the haltere and leg, and only one on the wing. All body parts bear microtrichia, except for the ovipositor. Mechanoreceptors are present in all body parts of adults. Sensilla on larvae are different from those on adults. Larval antenna is a dome shaped organ located in a cavity on the cephalic region. Four papillae distribute in the ventral organ, and five coeloconic sensilla and several basiconic sensilla are located on maxillary palp of larvae. Many basiconic sensilla are situated on the ventral depression close to posterior spiracular. This is the first overall observation about sensilla on the whole body of C. megacephala adults and larva...

Taxonomic revision of the genus Heliotropium (Boraginaceae s.l.) in south Yemen

The flora and fauna of Arabia, particularly southern Yemen, has recently attracted the interest of many authors. In this study, the genus Heliotropium L. (Boraginaceae) is taxonomically revised in southern Yemen. Ten species are recognized. Nomenclature, typification, representative specimens and a diagnostic key to all species are provided, along with their distribution in southern Yemen. The taxonomically most valuable characters in the genus are those of flowers (calyx, corolla, androecium and gynoecium) and nutlets, and those characters are thoroughly investigated and discussed. Both light and scanning microscopy are used in the investigation. Papillate anther apices (brush‐like) were recognized in some species. Connate anthers and deep or shallow ventral circular depressions on the nutlets were found to be useful in distinguishing members of H. sect. Orthostachys (viz. H. strigosum, H. rariflorum and H. ovalifolium), while winged nutlets were found only in H. pterocarpum. The length and hairiness of the style and stigma also proved to be taxonomically useful.

Evidence of spondyloarthropathy in the spine of a phytosaur (Reptilia: Archosauriformes) from the Late Triassic of Halberstadt, Germany.

Pathologies in the skeleton of phytosaurs, extinct archosauriform reptiles restricted to the Late Triassic, have only been rarely described. The only known postcranial pathologies of a phytosaur are two pairs of fused vertebrae of “Angistorhinopsis ruetimeyeri” from Halberstadt, Germany, as initially described by the paleontologist Friedrich von Huene. These pathologic vertebrae are redescribed in more detail in this study in the light of modern paleopathologic methods. Four different pathologic observations can be made in the vertebral column of this individual: 1) fusion of two thoracic vertebral bodies by new bone formation within the synovial membrane and articular capsule of the intervertebral joint; 2) fusion and conspicuous antero-posterior shortening of last presacral and first sacral vertebral bodies; 3) destruction and erosion of the anterior articular surface of the last presacral vertebra; and 4) a smooth depression on the ventral surface of the fused last presacral and first sacral vertebral bodies. Observations 1–3 can most plausibly and parsimoniously be attributed to one disease: spondyloarthropathy, an aseptic inflammatory process in which affected vertebrae show typical types of reactive new bone formation and erosion of subchondral bone. The kind of vertebral shortening present in the fused lumbosacral vertebrae suggests that the phytosaur acquired this disease in its early life. Observation 4, the smooth ventral depression in the fused lumbosacral vertebrae, is most probably not connected to the spondyloarthropathy, and can be regarded as a separate abnormality. It remains of uncertain origin, but may be the result of pressure, perhaps caused by a benign mass such as an aneurysm or cyst of unknown type. Reports of spondyloarthropathy in Paleozoic and Mesozoic reptiles are still exceptional, and our report of spondyloarthropathy in fossil material from Halberstadt is the first unequivocal occurrence of this disease in a Triassic tetrapod and in a phytosaur.

Synopsis of Paxillus MacLeay, 1819 (Coleoptera: Passalidae): distributional records and descriptions of four new species from Brazil.

Paxillus MacLeay, 1819 (Coleoptera: Passalidae) is redescribed, with new distributional records and descriptions of four species from Brazil. Paxillus reyesi new species is characterized by the first antennomere of antennal club reduced, slightly longer than half of the second antennomere; mesosternal scar straight, wide and deep. Paxillus chapadensis new species from the Chapada dos Guimarães (Mato Grosso, Brazil) has prostenal process centrally impressed with an opaque depression; and the scape of the antenna with a subapical dorsal spine, shallow ventral depression, and few erect setae. Paxillus manausensis new species from Manaus (Amazonas, Brazil) has high frontal ridges; mid-frontal tubercles high, acuminate and larger than the internal tubercles; and the central tubercle short. Paxillus uaupesensis new species from Uaupes (Amazonas, Brazil) has the mesosternal scar opaque, elongate and depressed; and the scutellum depressed. Diagnostic redescriptions and illustrations of known species from Brazil, a key to all known species, and a checklist with distributional data are provided.

Rigifila ramosa n. gen., n. sp., a Filose Apusozoan with a Distinctive Pellicle, is Related to Micronuclearia

We report the ultrastructure, 18S and 28S rDNA sequences, and phylogenetic position of a distinctive free-living heterotrophic filose protist, Rigifila ramosa n. gen., n. sp., from a freshwater paddyfield. Rigifila lacks cilia and has a semi-rigid, radially symmetric, well-rounded, partially microtubule-supported, dorsal pellicle, and flat mitochodrial cristae. From a central aperture in a ventral depression emerges a protoplasmic stem that branches into several branching filopodia that draw bacteria to it. Electron microscopy reveals a general cell structure similar to Micronuclearia, the only non-flagellate previously known in Apusozoa; the large basal vacuole is probably an unusual giant contractile vacuole. Phylogenetic analysis of concatenated rDNA sequences groups Rigifila and Micronuclearia as sisters with maximal statistical support. However, novel morphological differences unique to Rigifila, notably a double (not single) proteinaceous layer beneath the cell membrane, and cortical microtubules, lead us to place it in a new family Rigifilidae. Our morphological and molecular analyses show that Rigifila is the closest known relative of Micronuclearia. Therefore we group Micronucleariidae and Rigifilidae as a new order Rigifilida within the existing class Hilomonadea, which now excludes planomonads. Rigifilida groups weakly with Collodictyon (Diphyllatea). We discuss the possible relationships of Rigifilida to other Apusozoa and Diphyllatea.

Torosaurus Is Not Triceratops: Ontogeny in Chasmosaurine Ceratopsids as a Case Study in Dinosaur Taxonomy

BackgroundIn horned dinosaurs, taxonomy is complicated by the fact that the cranial ornament that distinguishes species changes with age. Based on this observation, it has been proposed that the genera Triceratops and Torosaurus are in fact synonymous, with specimens identified as Torosaurus representing the adult form of Triceratops. The hypothesis of synonymy makes three testable predictions: 1) the species in question should have similar geographic and stratigraphic distributions, 2) specimens assigned to Torosaurus should be more mature than those assigned to Triceratops, and 3) intermediates should exist that combine features of Triceratops and Torosaurus. The first condition appears to be met, but it remains unclear whether the other predictions are borne out by the fossil evidence.Methodology/Principal FindingsWe assessed the relative maturity of Torosaurus and Triceratops specimens by coding skulls for characters that vary with maturity, and then using a clustering analysis to arrange them into a growth series. We found that a well-defined sequence of changes exists in horned dinosaurs: development of cranial ornament occurs in juveniles, followed by fusion of the skull roof in subadults, and finally, the epoccipitals, epijugals, and rostral fuse to the skull in adults. Using this scheme, we identified mature and immature individuals of both Torosaurus and Triceratops. Furthermore, we describe the ventral depressions on the frill of Triceratops, and show that they differ in shape and position from the parietal fenestrae of Torosaurus. Thus, we conclude that these structures are not intermediates between the solid frill of Triceratops and the fenestrated frill of Torosaurus.Conclusions/Significance Torosaurus is a distinct genus of horned dinosaur, not the adult of Triceratops. Our method provides a framework for assessing the hypothesis of synonymy through ontogeny in the fossil record.

Lophoura brevicollum N. SP. (Copepoda: Siphonostomatoida: Sphyriidae), A Parasite of the Smooth Grenadier Nezumia liolepis (Gilbert, 1890) (Pisces: Macrouridae) from the Eastern Pacific, And A New Record And New Host of Lophoura unilobulata Castro R. And Gonzalez

Specimens of the deep-water macrourid Nezumia liolepis were caught during a survey of the effects of the oxygen minimum layer on the vertical distribution of crustaceans, polychaetes, and fishes in the Gulf of California. Two specimens were each carrying one parasitic copepod each, initially judged to be identical to Lophoura tetraloba in almost all respects. An additional specimen of N. liolepis carrying one copepod was collected in the San Pedro Channel between San Pedro and Santa Catalina Island (southern California), and another specimen of N. liolepis carrying another copepod, collected between Cabo Corrientes (Jalisco) and Manzanillo (Colima), Mexico, was found in the collection of the California Academy of Sciences. Detailed inspection revealed several important differences between L. tetraloba from the South China Sea and Tosa Bay (Japan), and the new material, which along with the different depth and distribution, support the hypothesis of a new sphyriid species, described here as L. brevicollum. Lophoura tetraloba and L. brevicollum can be separated by the length of the neck, the number of dorsal and ventral depressions of the genito-abdomen, the length of the egg sacs, and by the general shape of the posterior processes. Finally, a new record and a new host for L. unilobulata, as well as some comments on the systematic position of Driocephalus are given.

Ultrastructure, Life Cycle and Molecular Phylogenetic Position of a Novel Marine Sand-Dwelling Cercozoan: Clautriavia biflagellata n. sp.

Clautriavia is a genus of uncertain taxonomic affinity that was initially described as gliding cells with one prominent trailing flagellum and a mid-ventral groove. The genus has been classified either with euglenids on the basis of similar paramylon-like granules or with cercozoans, specifically Protaspis spp., on the basis of general similarities in cell morphology and behavior. We isolated and cultivated a novel species of Clautriavia, namely C. biflagellata n. sp., from marine sand samples collected from the west coast of Vancouver Island, Canada and characterized this isolate with high resolution microscopy (LM, SEM, and TEM) and small subunit (SSU) rDNA sequence. The gliding cells of C. biflagellata n. sp. were round to oval in outline (12-20 microm wide and 15-20 microm long), dorsoventrally flattened, and capable of engulfing other eukaryotic cells (e.g., diatoms). The cells possessed two recurrent flagella of unequal length that emerged from a subapical pit within a ventral depression: the longer prominent flagellum was about 2X the cell length; the shorter flagellum was inconspicuous and was confined to the ventral depression. Molecular phylogenetic analyses demonstrated that C. biflagellata n. sp. branched strongly within the Cercozoa, but was only distantly related to Protaspis spp. Instead, C. biflagellata n. sp. branched closely with the recently established Auranticordida clade, consisting of Auranticordis quadriverberis and Pseudopirsonia mucosa. This position was concordant with our ultrastructural data, which demonstrated several features shared by A. quadriverberis and C. biflagellata n. sp. that are not present in Protaspis spp.: (1) a dense distribution of pores on the cell surface; (2) a distinct layer of muciferous bodies immediately beneath the cell surface; (3) a robust microtubular root attached to the anterior end of the nucleus; (4) the absence of a thick cell covering; and (5) the absence of conspicuously condensed chromosomes.

Kinematics of benthic suction feeding in Callichthyidae and Mochokidae,with functional implications for the evolution of food scraping in catfishes

Food scraping has independently evolved twice from suction feeding in the evolution of catfishes: within neotropical Loricarioidea and paleotropical Mochokidae. To gain insight in the evolutionary transitions associated with the evolution towards scraping, we analyzed prey capture kinematics in two species of benthic suction feeders which belong to taxa that are closely related to the scraper lineages (respectively, Corydoras splendens and Synodontis multipunctatus), and compared it to prey capture in a more distantly related, generalist suction feeder (Clarias gariepinus). Simultaneous ventral and lateral view high-speed videos were recorded to quantify the movements of the lower jaw, hyoid, pectoral girdle and neurocranium. Additionally, ellipse modeling was applied to relate head shape differences to buccal expansion kinematics. Similarly to what has been observed in scrapers, rotations of the neurocranium are minimal in the benthic suction feeders, and may consequently have facilitated the evolution of a scraping feeding mechanism. The hypothesis that fish with a more laterally compressed head rely more heavily on lateral expansion of the buccal cavity to generate suction, was confirmed in our sample of catfish species. Since an important contribution of lateral expansion of the head to suction may avoid the need for a strong, ventral depression of the mouth floor during feeding, we hypothesized that this may have allowed a closer association with the substrate in the ancestors of scrapers. However, our hypothesis was not supported by an ancestral state reconstruction, which suggests that scraping probably evolved from sub-terminal mouthed ancestors with dorsoventrally flattened heads.

A new early dinosaur (Sauropodomorpha) from the Caturrita Formation (Late Triassic), Paran Basin, Brazil

A new early dinosaur, Unaysaurus tolentinoi gen. et sp. nov., from the continental Late Triassic red beds of the Caturrita Formation (Carnian-Norian, c. 225 million years old) of southern Brazil is described. U. tolentinoi is represented by a semi-articulated skeleton comprising an almost complete skull, lower jaw and postcranial elements. It differs from all other dinosaurs by several cranial (e.g. developed laterodorsally oriented process formed by frontal and parietal; deep ventral depression on the basisphenoid) and postcranial (presence of a conspicuous blunt ridge running on the lateral surface of the deltopectoral crest of humerus) characters. Unaysaurus represents the first prosauropod grade dinosaur from Brazil and a preliminary phylogenetic analysis indicates it to be closely related to the European Plateosaurus (Plateosauridae). The relationships of the Prosauropoda , however, are still controversial and more comprehensive studies are needed before a clear picture of the evolution and paleobiogeographic distributions of these dinosaurs can be presented.