Large Foramina Research Articles

Internal vertebral morphology of bony fishes matches the mechanical demands of different environments.

Fishes have repeatedly evolved characteristic body shapes depending on how close they live to the substrate. Pelagic fishes live in open water and typically have narrow, streamlined body shapes; benthic and demersal fishes live close to the substrate; and demersal fishes often have deeper bodies. These shape differences are often associated with behavioral differences: pelagic fishes swim nearly constantly, demersal fishes tend to maneuver near the substrate, and benthic fishes often lie in wait on the substrate. We hypothesized that these morphological and behavioral differences would be reflected in the mechanical properties of the body, and specifically in vertebral column stiffness, because it is an attachment point for the locomotor musculature and a central axis for body bending. The vertebrae of bony fishes are composed of two cones connected by a foramen, which is filled by the notochord. Since the notochord is more flexible than bony vertebral centra, we predicted that pelagic fishes would have narrower foramina or shallower cones, leading to less notochordal material and a stiffer vertebral column which might support continuous swimming. In contrast, we predicted that benthic and demersal fishes would have more notochordal material, making the vertebral column more flexible for diverse behaviors in these species. We therefore examined vertebral morphology in 79 species using micro-computed tomography scans. Six vertebral features were measured including notochordal foramen diameter, centrum body length, and the cone angles and diameters for the anterior and posterior vertebral cones, along with body fineness. Using phylogenetic generalized least squares analyses, we found that benthic and pelagic species differed significantly, with larger foramina, shorter centra, and larger cones in benthic species. Thus, morphological differences in the internal shape of the vertebrae of fishes are consistent with a stiffer vertebral column in pelagic fishes and with a more flexible vertebral column in benthic species.

Sodium Hypochlorite Accident during Canal Treatment: Report of Four Cases Documented According to New Standards

Hypochlorite accidents are relatively rare events. Therefore, there is a lack of precise and accurate reports in the scientific literature that could help clinicians better understand the phenomenon and associated risk factors. This study reported four hypochlorite accidents attributable to 5% NaOCl extrusion in patients who had undergone treatment of the maxillary elements canal treatments. In all cases, the accidents occurred during the irrigation phase and were characterised by intracanal bleeding, ecchymosis, and swelling on the hemiface corresponding to the treated tooth. Antibiotics, paracetamol, NSAID, corticosteroids, and cold or warm compresses for oedema were prescribed to treat the symptoms of the accidents. Significant improvement of symptoms was observed in all patients after 5–6 days. Anatomic risk factors such as apical fenestration, root perforation, and large foramina were identified as possible risk factors for the accidents. After the accidents, clinicians applied endodontic procedures for which there is no scientific evidence to continue endodontic treatments, such as changing the type of irrigant or the irrigation method. Our results suggest that using a standardised approach to document each hypochlorite accident will allow researchers to collect more accurate and detailed data that can subsequently be used to identify potential risk factors and better manage the symptomatology of hypochlorite accidents.

New remains of Eleutherocercus (Xenarthra, Cingulata, Glyptodontidae) from the Pampean and Northwestern regions of Argentina: morphology and phylogeny of late Neogene Doedicurinae

ABSTRACT The subfamily Doedicurinae is a monophyletic group of glyptodonts with their own anatomical features and is mostly known on the basis of the Pleistocene genus Doedicurus, one of the largest recorded taxa. The most distinctive character of the subfamily, unique within Cingulata, include the absence of ornamentation with large foramina, on the exposed surface of the carapace osteoderms. In terminal forms of the late Pleistocene, osteoderms have large foramina which tend to cross the entire thickness. The knowledge of the late Neogene diversity of the clade, as well as its evolutionary and geographical history, has increased in recent years, with important records in Argentina, where two late Miocene-Pliocene species are recognised: Eleutherocercus solidus from Catamarca and Tucumán provinces, and Eleutherocercus antiquus from Buenos Aires province. The most complete skull of E. antiquus from the early Pliocene Monte Hermoso Formation (ca. 5–4.2 Ma) is reported here. The specimen studied shows a conspicuous pathology on the parietal bones, first reported for fossil cingulates. In addition, the carapace of E. solidus is first described, on the basis of a partially complete specimen from the late Miocene-Pliocene (unknown stratigraphic level) from Tucumán province. Previous phylogenetic hypotheses of the relationships within the Doedicurinae, as well as their relationship with the remaining clades of Glyptodontidae, is tested in this study, adding new synapomorphies to the subfamily. The comparative study suggests that a third species previously proposed (E. paranaensis) from the ‘Mesopotamiense’ (late Miocene, Northeastern region of Argentina), must be considered as Eleutherocercus sp. Since their oldest record in the late Miocene, the latitudinal distribution of the Doedicurinae seems to have expanded rapidly reaching middle latitudes, particularly during the Pliocene, but during the Pleistocene (particularly the final lapse of this period), they began to retract latitudinally.

New furileusaurian remains from La Invernada (northern Patagonia, Argentina): A site of unusual abelisaurids abundance

Two new specimens of abelisaurid theropods from La Invernada fossil area (Bajo de la Carpa Formation; Santonian) are described. They correspond to an incomplete skull and several postcranial remains. MAU-Pv-LI-582 (skull) shares some morphological traits with other furileusaurs (Viavenator exxoni and Llukalkan aliocranianus) from the same area, such as: presence of a rounded knob on the anteromedial border of the supratemporal fossa, large foramina for the caudal middle cerebral veins, and a triangular basisphenoid recess with Llukalkan, and a basituberal web ventrally concave, a large common foramen for the exit of CNs III and IV, and particularly the absence of a caudal tympanic recess with Viavenator. MAU-Pv-LI-665 (vertebrae and ribs) shares some features with Viavenator, such as the presence of a single pneumatic foramen in the mid cervical centrum, and the shape and orientation of the neural spine of the mid dorsal vertebra. These findings, added to the previous ones, not only reveal the abundance of abelisaurids in this geographical area, but also the variety of morphotypes that coexisted during the middle of the Upper Cretaceous, at least in the north of Argentine Patagonia.

Foramina parietalia permagna: descrizione di un caso clinico e revisione della letteratura

The purpose of the present work is to expose the defects of parietal bone ossification and to identify the criteria for differential diagnosis and brain changes related to the condition, with particular attention to the venous developmental anomalies and the pathological features associated. Foramina parietalia permagna (FPP) are caused by an insufficient intramembranous ossification around the parietal notch that is normally obliterated in the fifth month of normal foetal development. During the first few years of life as calvarial growth continues, cranium bifidum tends to resolve into two distinct, large parietal foramina. Most people with FPP have a positive family history as the condition is inherited in an autosomal dominant fashion with high, but incomplete penetrance. Mutations of either MSX2 or ALX4 genes are associated with enlarged parietal foramina. Meningeal cortical vascular malformation of the straight sinus and persistent falcine sinus have also been reported in the literature as possible associated anomalies.

A new species of Caipirasuchus (Notosuchia, Sphagesauridae) from the Late Cretaceous of Brazil and the evolutionary history of Sphagesauria

Sphagesauridae is a group of notosuchian crocodyliforms from the Late Cretaceous of South America characterized by highly specialized jaws and dentition. Here, we describe a new sphagesaurid from the Santo Anastácio Formation (Caiuá Group, Bauru Basin), south-east Brazil. The specimen is composed of a partial palate, neurocranium, mandible and fragmentary teeth. It represents a new species that can be assigned to Caipirasuchus due to the presence of a lateromedially narrow and anteroposteriorly long mandibular symphyseal region, apicobasal ridges on the posterior teeth, a diastema between D5 and D6, and a linear row of large neurovascular foramina on the lateral surface of the dentary. It differs from previously described Caipirasuchus species based on a ventrolaterally inclined surface of the dentaries posterior to the tooth row, a connection between the anteroventral margin of the external mandibular fenestra and the floor of the Meckelian canal, and the anterior process of the angular forming a ‘V’-shaped suture in its contact with the splenial. The results of a phylogenetic analysis of notosuchians recovered the so-called ‘advanced notosuchians’ in a clade, for which we propose a phylogenetic definition and erect the name Sphagesauria. We also recovered two more inclusive clades encompassing an array of Mesozoic notosuchians, here named Xenodontosuchia, which includes Sphagesauria + Baurusuchia, and Eunotosuchia, including Xenodontosuchia, Uruguaysuchidae and other Cretaceous forms. http://zoobank.org/urn:lsid:zoobank.org:pub:FD8D706F-9E01-4C09-BE4E-DC3BEDE151DC

A new furileusaurian abelisaurid from La Invernada (Upper Cretaceous, Santonian, Bajo de la Carpa Formation), northern Patagonia, Argentina

ABSTRACT Abelisaurids are among the most abundant and diverse Patagonian Late Cretaceous theropods. Here, we present a new furileusaurian abelisaurid, Llukalkan aliocranianus gen. et sp. nov., represented by cranial remains from the Bajo de la Carpa Formation (Santonian) at La Invernada fossil area, northwestern Patagonia. Features characterizing this taxon include a possible caudal tympanic recess posterior to the columellar recess, a T-shaped lacrimal with jugal ramus lacking a suborbital process, and large foramina for caudal middle cerebral veins widely separated from the median supraoccipital crest. In addition to this, a bulge on the anteromedial border of the supratemporal fossa, tall and posteriorly projected paroccipital processes, basal tubera interconnected distally, a triangular basisphenoid recess, and a single foramen for the sphenoidal artery on the basisphenoid, differentiate Llukalkan from Viavenator exxoni. The latter is the other furileusaurian taxon from the same area and stratigraphic unit. Although the holotype of Llukalkan probably corresponds to a sub-adult—as the lacrimal morphology suggests— the possibility that it represents a juvenile of V. exxoni is discarded based mainly on the presence of a caudal tympanic recess (which is absent in V. exxoni). The probable coexistence of two abelisaurid taxa demonstrates that the abelisaurids were one of the most important—and likely the main—predator component of the ecosystems, not only in this area, but also in all of Patagonia, during the Late Cretaceous.

An exceptional neurovascular system in abelisaurid theropod skull: New evidence from Skorpiovenator bustingorryi.

Abelisaurids were one of the most successful theropod dinosaurs during Cretaceous times. They are featured by numerous derived skull traits, such as heavily ornamented bones, short and tall snout, and a strongly thickened cranial roof. Furthermore, nasals are distinctive on having two distinct nasal patterns: strongly transversely convex and heavily sculptured (e.g., Carnotaurus), and transversely concave, with marked bilateral crests and poorly sculptured surfaces (e.g., Rugops). Independently of the pattern, some abelisaurid nasals (e.g., Rugops) show a distinctive row of large foramina on the dorsal surface, which were in general associated to skin structures (scales). Skorpiovenator bustingorryi is a derived abelisaurid coming from the upper Cretaceous beds of northwestern Patagonia, represented by an almost complete skeleton including a well-preserved skull. Particularly, the skull of Skorpiovenator shows nasal bones characterized by being transversely concave, rimmed by lateral crests and with a conspicuous row of foramina on the dorsal surface. But more interesting is that the skull roof also exhibits a row of large foramina that seem to be continuous with the previous nasal foramina. CT scans made on the skull corroborates a novel feature within theropods: the nasal foramina on the external surface are linked to an internal canal that runs across the nasal bones. We compared this feature with CT scans of Carnotaurus and revealed that it also possess an internal system as in Skorpiovenator, but being notably smaller. The symmetry and disposition of the foramina in the nasal and skull roof bones of Skorpiovenator would indicate a neurovascular correlate (i.e., blood vessels and nerves), probably to the lateral nasal and supraorbital vessels and the trigeminal nerve. The biological significance of such neurovascular system can be conjectured from several hypotheses. A possible one involves an enhanced blood volume in these bones linked to a zone of thermal exchange, which may help avoid overheat of encephalic tissues. Another plausible hypothesis takes into account the presence of display skin structures in which blood volume nourished the mineralized skin, which would have a role in intraspecific communication. However, other more speculative explanations should not be discarded such as a correlation with integumentary sensory organs.

A rostral neurovascular system in the mosasaur Taniwhasaurus antarcticus.

Mosasaurs were a cosmopolitan group of marine squamate reptiles that lived during the Late Cretaceous period. Tylosaurinae mosasaurs were characterized for having an edentulous rostrum anterior to the premaxillary teeth. External morphology of the snout of the tylosaurine Taniwhasaurus antarcticus from the Upper Cretaceous beds at James Ross Island (Antarctic Peninsula) shows a complex anatomy with diverse large foramina and bone sculpture. A computed tomography scan of the Taniwhasaurus rostrum revealed a complex internal neurovascular system of branched channels in the anteriormost part of the snout. Systems like this are present in extant aquatic vertebrates such as cetaceans and crocodiles to aid them with prey detection, and are inferred to have functioned in a similar manner for several extinct reptile clades such as plesiosaurs and ichthyosaurs. Thus, it is probable that Taniwhasaurus also was able to detect prey with an enhanced neural system located in its rostrum. This condition may be more widespread than previously thought among mosasaurs and other marine reptiles.

Cricodon metabolus (Cynodontia: Gomphodontia) from the Triassic Ntawere Formation of northeastern Zambia: patterns of tooth replacement and a systematic review of the Trirachodontidae

ABSTRACTThe partial skull and postcranial skeleton of a subadult Cricodon metabolus is described as the first record of a trirachodontid cynodont from the upper Ntawere Formation of northeastern Zambia. On the basis of features in the type and referred specimen, Cricodon metabolus can be diagnosed by the presence of a posterior cingulum in the lower postcanines that opens labially in a ‘V’-shaped notch between a large basal cuspule and the steeply descending posterior ridge of the principal labial cusp, and by a pair of large foramina on the maxillary shelf. The subadult specimen shows evidence for four series of postcanine teeth, including a wave of small gomphodont teeth being replaced by a younger wave of larger gomphodont teeth. Cladistic analysis of 75 characters in 27 cynodonts recovers Trirachodontidae as a clade that is the sister taxon of Traversodontidae. Trirachodontidae includes four species, with Langbergia modisei as the earliest diverging taxon. Our analysis also recovers ‘Trirachodon’ kannemeyeri as the sister taxon of Cricodon metabolus, leading us to transfer the former species to the genus Cricodon. Trirachodon berryi is determined to be a valid taxon that is sister to Cricodon. Two reputed trirachodontids from China, Sinognathus gracilis and Beishanodon youngi, do not appear as trirachodontids in our analysis but rather resolve as sister taxa within Traversodontidae. Although this hypothesis of relationships is not supported by the current analysis, we suggest that the two Chinese species might be probainognathians that convergently evolved expanded postcanine teeth rather than gomphodontians.Citation for this article: Sidor, C. A., and J. A. Hopson. 2018. Cricodon metabolus (Cynodontia: Gomphodontia) from the Triassic Ntawere Formation of northeastern Zambia: patterns of tooth replacement and a systematic review of the Trirachodontidae; pp. 39–64 in C. A. Sidor and S. J. Nesbitt (eds.), Vertebrate and Climatic Evolution in the Triassic Rift Basins of Tanzania and Zambia. Society of Vertebrate Paleontology Memoir 17. Journal of Vertebrate Paleontology 37(6,Supplement).

Clinical anatomy of the orbitomeningeal foramina: variational anatomy of the canals connecting the orbit with the cranial cavity.

In addition to the optic canal and the superior orbital fissure, orbits are connected with the cranial cavity via inconstant canals including the orbitomeningeal foramen. This study has been carried out in order to define many anatomical and radiological details of the orbitomeningeal foramen that are relevant in the clinical practice. Almost 1000 skulls and 50 computerized tomographies were examined to determine incidence, number, length, and caliber of the orbitomeningeal foramen as well as the topography of their orbital and cranial openings. A retrospective study of angiographies carried out on more than 100 children was performed to look for arteries candidate to run through the orbitomeningeal foramen. Orbitomeningeal foramina were detected in 59.46% of skulls and in 54% of individuals by computerized tomography. Orbits with two to five foramina were found. Canals were classified as M-subtype or A-subtype depending on their cranial opening. Large foramina, with the caliber ranging between 1 and 3 mm, were found in 12.17% of orbitomeningeal foramen-bearing orbits. By computed tomography the average caliber measured 1.2 ± 0.3 and 1.5 ± 0.5 mm (p < 0.005) at the orbital and cranial openings, respectively (p < 0.005). Angiographies showed meningo-lacrimal and meningo-ophthalmic arteries, meningeal branches of the lacrimal and supraorbital arteries, and some unidentified arteries that could pass through the orbitomeningeal foramina. Orbitomeningeal foramina are a common occurrence. When large they may house important arteries that can be the source of severe bleedings during deep dissection of the lateral wall of the orbit. Orbital surgeons should be aware of their existence.

Variational anatomy of the orbitomeningeal foramen

In addition to the optic canal and the superior orbital fissure, orbits are connect - ed with the cranial cavity via inconstant canals including the orbitomeningeal fora- men. Though the orbitomeningeal foramen received considerable attention in the last twenty years, many of its anatomical details relevant for clinical practice still await to be defined. Almost 1000 skulls and 50 computerized tomographies were examined to deter- mine incidence, number, length and caliber of the orbitomeningeal foramen as well as the topography of their orbital and cranial openings. A retrospective study of angi- ographies performed on more than 100 children was performed to look for arteries candidate for running through the orbitomeningeal foramen. Orbitomeningeal foramens were detected in 59.5% of skulls and in 54% of indi- viduals by computerized tomography. Orbits with two to five foramina were found. Canals were classified as M-subtype or A-subtype depending on their cranial open- ing into the middle or the anterior cranial fossa. Large foramina, with the caliber ranging between 1 and 3 mm, were found in 12.2% of orbitomeningeal foramen- bearing orbits. By computed tomography the average caliber measured 1.2±0.3 mm and 1.5±0.5 mm (p<0.005) at the orbital and cranial openings respectively (p<0.005). Angiographies showed meningolacrimal and meningoophthalmic arteries, meningeal branches of the lacrimal and supraorbital arteries, and some unidentified arteries that could pass through the orbitomeningeal foramina. Orbitomeningeal foramina are a common occurrence. When large they may house important arteries that can be the source of severe bleedings during deep dissection of the lateral wall of the orbit. Orbital surgeons should be aware of their existence.

First Neogene skulls of Doedicurinae (Xenarthra, Glyptodontidae): morphology and phylogenetic implications

Among Glyptodontidae, Doedicurinae (late Miocene–early Holocene) includes the glyptodonts with the largest size and latest records. Doedicurinae is mainly characterised by a smooth surface of the osteoderms with large foramina, and a particular morphology of the caudal tube. All taxa except one (Doedicurus clavicaudatus) have been recognised and characterised on the basis of remains of caudal tubes and/or dorsal carapaces. This situation produced an evident overestimation of the real diversity of this group, and a taxonomic revision is needed. In fact, no Neogene skulls were known. We present and describe the first two Neogene skulls belonging to Doedicurinae (cf. Eleutherocercus antiquus). The materials come from the El Polvorín and Chapadmalal Formations, in the surroundings of Olavarría and Mar del Plata localities, respectively (Buenos Aires province, Argentina). A cladistic analysis was carried out in order to situate these materials among Glyptodontidae and inferring new synapomorphies at skull level in Doedicurinae. Cf. Eleutherocercus antiquus clusters with the Pleistocene species Doedicurus clavicaudatus showing three unambiguous synapomorphies, which in turn represents the first skull synapomorphies for Doedicurinae. Finally, the presence of cf. Eleutherocercus antiquus in the El Polvorín and Chapadmalal Formations suggests that the stratigraphic distribution of this species could include the Montehermosan–Chapadmalalan interval.

Morphometric Analysis of the Foramen Magnum

Abstract OBJECTIVE To further elucidate the importance of anatomic variations in morphology of the foramen magnum and associated clinical implications, we conducted a morphometric study. METHODS Seventy-two dry skulls were used for this study. Digital images were obtained of the foramen magnum from an inferior view. These images were studied using a computer-assisted image analysis system. Next, an image processor was used to calculate pixel differences between 2 selected points, which allowed accurate translation of pixel differences into metric measurements. RESULTS We found that the mean surface area of the foramen magnum was 558 mm2, the mean anteroposterior diameter was 3.1 cm, and the mean horizontal diameter was 2.7 cm. For comparison, surface areas were classified into 3 types based on size. Type I foramina were identified in 20.8% of the dry skulls (15 skulls) and exhibited a surface area of less than 500 mm2. Type II (66.6%, 48 skulls) was applied to foramina of an intermediate size with surface areas ranging between 500 to 600 mm2. Type III (12.5%, 9 skulls) was applied to large foramina with surface areas of more than 600 mm2. CONCLUSION These data may be of use as a morphometric database for description of “normal” variants of foramen magnum morphology.

Relation Between Inheritance of Cyanotic Congenital Heart Disease and Persistent Foramen Ovale

Cyanotic congenital heart disease (CCHD) usually occurs sporadically, but occasionally it is familial without evidence of Mendelian inheritance. The investigators previously reported an association between dominant inheritance of clinically significant atrial shunts (large persistent foramina ovale and small atrial septal defects) and migraine with aura in some families. In 1 family, 4 patients with CCHD were linked by relatives with atrial shunts. The presence of atrial shunts and migraine symptoms was investigated in another family in which 3 members had CCHD. Contrast echocardiography was used to detect whether atrial right-to-left shunts were present in family members. A consultant neurologist, who was blinded to cardiac findings, diagnosed and categorized migraine symptoms. In this family, relatives with atrial right-to-left shunts linked 3 members who had CCHD. There appears to be dominant inheritance of atrial shunts, which is linked to inheritance of CCHD in some families. In conclusion, it is possible that the gene responsible most often causes an atrial shunt but sometimes causes more complex heart disease.

Adeopapposaurus mognai, gen. et sp. nov. (Dinosauria: Sauropodomorpha), with comments on adaptations of basal Sauropodomorpha

ABSTRACT Prosauropods are basal sauropodomorphs that were the major terrestrial faunal components from the Norian until their extinction during the Toarcian. Their status as a natural group is debatable. In the present work I describe Adeopapposaurus mognai, a new sauropodomorph from the Cañón del Colorado Formation, in northwestern Argentina. Diagnostic autapomorphies and combination of characters of Adeopapposaurus include a series of large foramina in a sub-vertical row on the lateral surface of the premaxilla; strongly rugose depression bordered by a protuberance with a series of foramina in a sub-vertical row, on the lateral surface of the anterior end of the dentary; eleven anteroposteriorly elongated cervical vertebrae and thirteen dorsal vertebrae with neural arches taller than the respective centra. Phylogenetically Adeopapposaurus is resolved as the sister group to Massospondylus; differing from the latter based on differences in mandible and premaxilla and addition of one dorsal vertebra to the neck. The specimens described here reveal numerous herbivorous adaptations, including the presence of a highly vascularized bony plate in the premaxilla and dentary, which indicates that it had a horny beak.

On the skull of a pliosaur (Plesiosauria; Pliosauridae) from the Upper Cretaceous (Early Turonian) of the North American Western Interior

Abstract A partial pliosaur skull reveals anatomical features poorly known for Plesiosauria. The specimen lacks recorded contextual information, however preservational character and nannofossil analysis (earliest Turonian) suggests origination from the upper Greenhorn Limestone. The vomers bifurcate near their posterior termination, and are overlapped by long, slender extensions of the anterior pterygoids. The latter character has only recently been noted and may be variously developed in many if not all plesiosaurs. Large foramina commonly referred to as the ‘internal nares’ are formed at the juncture of the palatines, vomers, and maxillae. Configuration of the palatal elements differs in several ways from the only well established pliosaurid taxon of the North American Cretaceous, Brachauchenius. Particular differences include a more visibly elongate and lanceolate shape of the vomers, palatines which do not project as far anteriorly (similarly for the ‘internal nares’), and a squared posterior terminat...

A new baurusuchid crocodyliform (Archosauria) from the Late Cretaceous of Patagonia (Argentina)

A new baurusuchid, Wargosuchus australis gen. et sp. nov., coming from the Bajo de La Carpa Formation, Neuquén Province (Argentina), is described. This new taxon is based on a fragment of snout and a portion of the cranial roof. Wargosuchus differs from other crocodyliforms by possessing a deep median groove on the frontals, a contact between nasals and frontals extremely reduced, a large depression for the olfactory bulbs, three large foramina surrounding the large, smooth perinarial depression, and a hypertrophied, conical last premaxillary tooth followed by a large paracanine fossa. The finding of Wargosuchus in Patagonia (Argentina), a taxon with a strong resemblance to Brazilian baurusuchids, reinforces the hypothesis of a similar biota between both regions by the Late Cretaceous. Wargosuchus and Cynodontosuchus represent the only Argentinian mesoeucrocodylians to be included within Baurusuchidae. This finding extends the number of crocodyliforms from the Bajo de la Carpa Formation, which, in turn, corresponds to the most taxonomically diverse one in Argentina.

MORPHOLOGICAL VARIABILITY IN NEODENTICULA SEMINAE, A MARINE PLANKTONIC DIATOM IN THE NORTH PACIFIC OCEAN AND BERING SEA

Image analysis of the living, marine planktonic diatom, Neodenticula seminae (Simonsen et Kanaya) Akiba et Yanagisawa, collected during summers of 1996–99 off northeast Japan, the Kurile Islands and in the Bering Sea revealed significant intraspecific morphological variability. SEM observations showed the internal valve morphology to be more variable in populations from the northwestern Pacific than in those from the Bering Sea, with the latter having lower variability for almost all morphometrics. In particular, the robustness of the basal ridge in the Bering Sea population was readily apparent, both visually and statistically. This implies that valves from the northwestern Pacific have relatively more delicate basal ridges and larger foramina.

New taxa of Japanese and New Zealand Eurystomellidae (Phylum Bryozoa) and their phylogenetic relationships

As presently recognized, the small cheilostome bryozoan family Eurystomellidae (superfamily Catenicelloidea) comprises just two genera: EurystomellaLevinsen, 1909, with three Recent species, and SelenariopsisMaplestone, 1913; with one Recent and two fossil species. Within Eurystomella sensu lato, colonies range from uni-/biserial to multiserial and the smooth gymnocystal frontal shields of zooids may be entire or have one to several large foramina. Here we describe seven new Recent species of encrusting eurystomellids from New Zealand and Japan. Including species of Selenariopsis, a cladistic analysis was carried out on 11 eurystomellid species and five outgroup species, the latter representing the families Cribrilinidae, Euthyroididae, Petalostegidae, and Catenicellidae. The results of the analysis support restricting Eurystomella to multiserial species with large frontal foramina, median suboral sutures, and basal pore-chambers. Two new genera, both with imperforate frontal shields and uniporous mural septula, are segregated from Eurystomella: uni-/biserial Zygopalme, with a median suboral suture and accssory perforations in the ovicellular kenozooid, and multiserial Integripelta, lacking the suture and accessory perforations. © 2002 The Linnean Society of London, Zoological Journal of the Linnean Society, 2002, 136, 199–216.