Marginal Teeth Research Articles

Dentispicotermes trapezia (Isoptera: Termitidae: Amitermitinae), a new termite species from the Pantanal-Chaco Region of South America

Dentispicotermes trapezia sp. nov. is described from the soldier and worker castes of specimens collected in Pantanal-Chaco Region of Bolivia and Paraguay. The soldiers differ from its five congeners in having a trapezoidal frontal protuberance with in-line marginal teeth. A key to Dentispicotermes soldiers is provided.

Early ray‐finned herbivores: the dental system of Eurynotoidiidae (Actinopterygii; middle–late Permian, European Russia) and implications for palaeobiology and palaeoecology

AbstractEurynotoidiformes are a little‐known group of actinopterygian fishes from the Permian of European Russia, characterized by the possession of multicuspid marginal teeth arranged in a single row. Morphologically, the teeth resemble those of Recent Cichlidae, Acanthuridae, Siganidae or Serrasalmidae, suggesting similar trophic adaptations related to herbivory. Tooth histology is similar to the majority of basal actinopterygians (composed of dentine, acrodin and collar enamel). Teeth are ankylosed in their attachment, and labial pleurodont in implantation, strengthening the tooth. The multicuspid tooth crowns derive from conical teeth of predatory or omnivorous ancestors, analogous to the evolution of multicuspid teeth in cichlid fishes. Tooth replacement in eurynotoidiforms is most comparable to an alternating pattern, with a possible simultaneous, unilateral replacement occurring in the whole jaw, similar to characiform fishes. Replacement teeth were formed extraosseously. Teeth of the inner dental arcade were conical. Based on comparisons with the teeth of extant actinopterygians specialized for herbivory, along with functional morphological analysis and consideration of wear patterns, we hypothesize that eurynotoidiforms represent the oldest known actinopterygians specialized for herbivory. Several strategies of herbivory in Recent actinopterygians were already realized by eurynotoidiforms as early as the Late Palaeozoic (middle and late Permian): grazing/cutting filamentous algae (Lapkosubia spp., Isadia suchonensis), browsing/biting off macrophyte fragments (Isadia aristoviensis), scraping/harvesting periphyton from hard substrates (Isadia opokiensis, I. arefievi). However, notable morphological differences in the jaws (elongate) and tooth arrangement (homodont along the jaw, functional teeth separated) suggest that this Permian experiment in herbivory followed different pathways compared to extant taxa.

Cranial osteology and a new diagnosis of the late Permian pareiasaur Nanoparia luckhoffi (Broom, 1936) from the Karoo Basin of South Africa, and a consolidated pareiasaurian phylogeny

Pareiasaurs were an enigmatic and diverse group of parareptilian herbivores of the middle and late Permian. Nanoparialuckhoffi was erected in 1936 but remains the least well-known member of four “dwarf” pareiasaurs that comprise Pumiliopareiasauria. After new preparation of the holotype, we present the first detailed cranial description of Nanoparialuckhoffi and a new diagnosis for the taxon based on seven autapomorphies: (1) an additional bone on the posterior margin of the cheek flange between the squamosal and quadratojugal; (2) a pyramidal-shaped parietal; (3) a very short, square lacrimal; (4) paired prepalatal foramina positioned anterolaterally on the internal premaxillary palatal flange; (5) notch on anteromedial border of the choana; (6) a ventral flange formed by the lateral margin of the internal tabulars; and (7) tabulars that extend posteriorly further than the supratemporals. We find evidence supporting a juvenile ontogenetic state for the holotype, including small skull; unossified open cranial sutures; an unossified dorsal braincase; and fewer marginal teeth than most pareiasaurs. An updated phylogeny recovers Nanoparia as a sister taxon to Provelosaurusamericanus from Brazil and remains a constituent member of Pumiliopareiasauria. Keywords: Nanoparia, Pumiliopareiasauria, Pareiasauria, Parareptilia, late Permian, Gondwana.

Morphological Variability and Function of Labial Cartilages in Sharks (Chondrichthyes, Elasmobranchii).

(1) Background: Labial cartilages (LCs), as their name suggests, lie in the folds of the connective tissue, the lips, framing the gape of elasmobranch chondrichthyans. As such, these cartilages lie laterally to the jaws and marginal teeth. They are considered to influence the ability of creating suction during the feeding process. As past studies have shown, LCs in sharks are as diverse as their varied feeding techniques and differ between species in number, size, shape, and position. This allows establishing parameters for inferring the feeding and hunting behaviors in these ecologically important fishes. (2) Methods: We present a study of LCs based on the CT scans of more than 100 extant shark species and, therefore, represent at least one member of every living family within the Euselachii, excluding batoids. (3) Results: Accordingly, sharks without labial cartilages or that have only small remnants are ram feeders or use pure biting and mainly occupy higher trophic levels (tertiary and quaternary consumers), whereas suction-feeding sharks have higher numbers (up to five pairs) of well-developed LCs and occupy slightly lower trophic levels (mainly secondary consumers). Species with unique feeding strategies, like the cookie-cutter shark (Isistius brasiliensis, an ectoparasite), display distinct shapes of LCs, while generalist species, conversely, exhibit a simpler arrangement of LCs. (4) Conclusions: We propose a dichotomous identification key to classify single LCs into different morphotypes and propose combinations of morphotypes that result in suction feeding differing in strength and, therefore, different hunting and feeding strategies. The conclusions of this study allow to infer information about feeding strategies not only in extant less-known sharks but also extinct sharks.

The Sphagnum cuspidatum complex: phylogeny, species delimitation, and morphology

Abstract The use of species as a concept is an important metric for assessing biological diversity and ecosystem function. However, delimiting species based on morphological characters can be difficult, especially in aquatic plants that exhibit high levels of variation and overlap. The Sphagnum cuspidatum complex, which includes plants that dominate peatland hollows, provides an example of challenges in species delimitation. Microscopic characters that have been used to define taxa and the possibility that these characters may simply be phenoplastic responses to variation in water availability make species delimitation in this group especially difficult. In particular, the use of leaf shape and serration, which have been used to separate species in the complex, have resulted in divergent taxonomic treatments. Using a combination of high-resolution population genomic data (RADseq) and a robust morphological assessment of plants representing the focal species, we provide evidence to evaluate putative species in this complex. Our data support the recognition of S. cuspidatum, S. fitzgeraldii, S. mississippiense, and S. trinitense as genetically distinct species that can be separated morphologically. These results indicate that S. viride does not differ genetically from S. cuspidatum. Our results are broadly relevant to other aquatic groups where leaf shape and marginal teeth are used to distinguish species.

New record of Gayralia kuroshiensis (Ulotrichales: Chlorophyta) in Korea based on morphological and molecular analyses

Monostromatic algae, Monostroma and Gayralia, are taxonomically complex, with several nomenclatural changes over the past years owing to indistinguishable morphological features. Several Monostroma species were recently transferred to the genus Gayralia based on their ontogeny and molecular analysis. There is no record of the occurrence of Gayralia in Korea, whereas three species of Monostroma have been reported. We conducted a molecular analysis based on the nuclear ribosomal internal transcribed spacer region of the specimens from Jeju, Korea, that we considered to be included in the genus Monostroma. The specimens from this study and five sequences of Monostroma nitidum downloaded from the GenBank were conspecific with Gayralia kuroshiensis from Japan but distinct from the M. nitidum syntype from Australia. G. kuroshiensis has a single, expanded, laminar, monostromatic thallus that is light to mid-green. The thallus thickness in the marginal regions was similar to that of G. kuroshiensis from Japan, with an undulate shape and no marginal teeth. The cells in surface view were in groups of two, rectangular to polygonal in shape, with one to three pyrenoids per cell. Based on the morphological and molecular analyses, we report a new record of G. kuroshiensis in Korea.

Description of a New Species of Hua (Gastropoda: Semisulcospiridae) from Guizhou, China, Based on Morphology and Molecular Evidence.

A new species of Hua, Hua qiannanensis sp. nov., is described from Guizhou Province, China, based on morphological and molecular evidence. The new species can be distinguished from its congeners by the following combination of characters: the smooth shell, only three smaller cusps of lateral teeth on the inner side, outer marginal teeth with eight flattened and rounded denticles, an ovipositor pore in females, and BW/H ≥ 80%, B/H = 76.8-82.3%. Molecular analysis based on partial mitochondrial COI and 16S rDNA also supports the systematic position of the new taxon.

A new Carboniferous edaphosaurid and the origin of herbivory in mammal forerunners

Herbivory evolved independently in several tetrapod lineages during the Late Carboniferous and became more widespread throughout the Permian Period, eventually leading to the basic structure of modern terrestrial ecosystems. Here we report a new taxon of edaphosaurid synapsid based on two fossils recovered from the Moscovian-age cannel coal of Linton, Ohio, which we interpret as an omnivore–low-fibre herbivore. Melanedaphodon hovaneci gen. et sp. nov. provides the earliest record of an edaphosaurid to date and is one of the oldest known synapsids. Using high-resolution X-ray micro-computed tomography, we provide a comprehensive description of the new taxon that reveals similarities between Late Carboniferous and early Permian (Cisuralian) members of Edaphosauridae. The presence of large bulbous, cusped, marginal teeth alongside a moderately-developed palatal battery, distinguishes Melanedaphodon from all other known species of Edaphosauridae and suggests adaptations for processing tough plant material already appeared among the earliest synapsids. Furthermore, we propose that durophagy may have provided an early pathway to exploit plant resources in terrestrial ecosystems.

Unravelling the conoidean gastropods assigned to the genus Propebela (Gastropoda: Mangeliidae) from south-western Atlantic deep waters

ABSTRACT A new genus of conoidean gastropods of the family Mangeliidae, Notopropebela gen. nov., is herein described to include N. profunda (Castellanos and Landoni, 1993) previously in the genus Propebela Iredale, 1918, and two new species from the deep waters off south-western Atlantic Argentine. This new genus is characterised by small rhomboid shells with axial riblets and spiral cords, absent operculum, and radula of semi-enrolled marginal teeth. Both new species are distinguished from N. profunda by the presence of pustules covering the shell. Notopropebela pustulata sp. nov. was collected at depths ranging from 530 to 2845 m off Argentina within the Mar del Plata Submarine Canyon in the north and Burdwood Bank surroundings in the south. Notopropebela petu sp. nov., distinguished from N. pustulata by a larger spire and subsutural ramp, was described from material collected from 210 m off Buenos Aires province. The radula and details of the shell and protoconch of both new species were studied from material deposited in the collections of Museo Argentino de Ciencias Naturales (MACN) and Museo de La Plata (MLP). We conclude that the genus Propebela is absent from the south-western Atlantic. http://www.zoobank.org/urn:lsid:zoobank.org:pub:act:BABC3CF0-0301-43D5-8F61-01EB94F7D647 http://www.zoobank.org/urn:lsid:zoobank.org:pub:act:CA51AFD6-0C1D-49C2-91EE-BF3F7DBA3625 http://www.zoobank.org/urn:lsid:zoobank.org:pub:act:D0130F68-6631-4368-91B1-5E68AF0B3C85

Acrobolbus mashpianus (Acrobolbaceae, Marchantiophyta) sp. nov. from the Northern Andes of Ecuador—Notes on the Bryophytes of Ecuador VII

Acrobolbus mashpianus, a leafy liverwort of the family Acrobolbaceae, is described as new to science from the Chocó Biogeographical Region. It is characterized by strongly asymmetrical, deeply bilobed leaves with ciliate marginal teeth. The new species is illustrated and its relationships within the genus Acrobolbus are discussed. A key to the Ecuadorian species of Acrobolbus is provided.

Main patterns of radula formation and ontogeny in Gastropoda.

Gastropoda is morphologically highly variable and broadly distributed group of mollusks. Due to the high morphological and functional diversity of the feeding apparatus gastropods follow a broad range of feeding strategies: from detritivory to highly specialized predation. The feeding apparatus includes the buccal armaments: jaw(s) and radula. The radula comprises a chitinous ribbon with teeth arranged in transverse and longitudinal rows. A unique characteristic of the radula is its continuous renewal during the entire life of a mollusk. The teeth and the membrane are continuously synthesized in the blind end of the radular sac and are shifted forward to the working zone, while the teeth harden and are mineralized on the way. Despite the similarity of the general mechanism of the radula formation in gastropods, some phylogenetically determined features can be identified in different phylogenetic lineages. These mainly concern shape, size, and number of the odontoblasts forming a single tooth. The radular morphology depends on the shape of the formation zone and the morphology of the subradular epithelium. The radula first appears at the pre- and posttorsional veliger stages as an invagination of the buccal epithelium of the larval anterior gut. The larval radular sac is lined with uniform undifferentiated cells. Each major phylogenetic lineage is characterized by a specific larval radula type. Thus, the docoglossan radula of Patellogastropoda is characterized by initially three and then five teeth in a transverse row. The larval rhipidoglossan radula has seven teeth in a row with differentiation into central, lateral, and marginal teeth and later is transformed into the adult radula morphology by the addition of lateral and especially marginal teeth. The taenioglossan radula of Caenogastropoda is nearly immediately formed in adult configuration with seven teeth in a row.

Juvenile morphology of the ornamental crab Mithraculus forceps A. Milne-Edwards, 1875 (Crustacea, Brachyura)

The morphology of juveniles of Mithraculus forceps A. Milne-Edwards, 1875, raised in the laboratory, is described. The larvae were obtained from ovigerous females collected in the wild, maintained in the rearing system for culture of crabs (400 L). A total of 229 larvae (zoea I), from 7 females were distributed in lots of 20 larvae kept in glass flasks (500 ml), with seawater circulation and temperature and salinity constants, which were checked daily for molts or deaths. After the larvae reached the juvenile stage, exuviae and dead specimens were deposited in a scientific collection. We analyzed the external morphology (N = 10 ind.) of each size class (total = 8). We determined the number of size classes, based on carapace width CW vs. carapace length CL (mm) and its dispersion points, in which we can observe non-hierarchical groupings with no size classes overlapping. We analyzed the relative growth of the juveniles using the technique "Standard Major Axis'' (Type II regression). The relationships CW vs. CL and CW vs. AW showed negative allometry (b < 1; p < 0.05). The relationships CW vs. CPH and CW vs. CPL are isometric (b = 1; p > 0.05). The most remarkable morphological characters of the juveniles (first size class) are the following: spines at the anterior margin of the carapace, inner marginal teeth in the propodus and dactylus of the chelipeds, number of articles in the antennular endopod and the maxillular endopod, absence of setae on the maxillar endopod, and absence of rudimentary pleopods.

Molecular and morphological evidence reveals a new fern species of Hymenasplenium (Aspleniaceae) from south and southwestern China.

Hymenaspleniumobtusidentatum, a new fern species of the H.excisum subclade of Hymenasplenium (Aspleniaceae) from south and southwestern China was described. Molecular phylogenetic analyses and morphological observations of H.obtusidentatum and related species clearly indicated that this is a distinct taxonomic entity. Phylogenetically, H.obtusidentatum was confirmed to represent a diverging lineage in the H.excisum subclade of Hymenasplenium and was closely related to one lineage that includes accessions identified as H.obscurum, H.pseudobscurum and H.tholiformis. Morphologically, H.obtusidentatum can be distinguished by the combination of its lamina base truncate, stipe not shiny and with color of reddish brown to dark brown, and pinna marginal teeth that are not sharp, but blunt or rounded. A complete species description and comparison with related species in the H.excisum subclade were provided. The holotype of H.obtusidentatum was designated.

The first record of mosasaurs (Squamata: Mosasauridae) from the West Indies and its paleobiogeographical implications

Remains of Cretaceous vertebrates have been scarce in the fossil record of Cuba, but recent exploration of Upper Cretaceous outcrops in the central part of the island has led to the discovery of new fossil-bearing deposits from nearshore depositional environments. Here, we report upon two isolated marginal teeth, which we identified as belonging to the genus Mosasaurus. The specimens described here, recovered from two upper Campanian – lower Maastrichtian outcrops in central Cuba, represent the first record of mosasaurs from the West Indies, and along with other marine fossils suggest that the Caribbean played an important role in the faunal interconnection across seaways and oceans in the region.

Hymenaspleniumtholiformis (Aspleniaceae), a new fern species from southeastern Xizang, China based on morphological and molecular evidence.

A new species of Aspleniaceae, Hymenaspleniumtholiformis sp. nov., is described from Medog County in southeastern Xizang, China. The new species is morphologically similar to H.apogamum and H.szechuanense, but the former has ascending pinnae, pinna apex obtuse to rounded, pinna-marginal teeth entire, and veins terminating just below marginal teeth. Phylogenetic analysis based on five plastid markers confirmed that this new species represents a diverging lineage in the H.excisum subclade of Hymenasplenium.

Redescription of Rhinus ciliatus (Gastropoda: Simpulopsidae), An Endemic Species from the Atlantic Rainforest in Brazil

The genus Rhinus Martens, 1860, is represented in Brazil by about twenty species, which are predominantly found in the Atlantic rainforest, an endangered ecosystem with extraordinary biodiversity and high endemism. There is a dearth of detailed morphological data for most species of the genus Rhinus, and the anatomy of only a few species has been described. Rhinus ciliatus, an endemic species from southwestern Brazil, is known by few conchological traits and scarce anatomical data from the reproductive system and pallial cavity. In this study, we redescribe the shell morphology and soft body anatomy of Rhinus ciliatus in detail and compare the new data with known traits of other closely related species. Rhinus ciliatus is diagnosed by the following features: (i) transition from protoconch to teleoconch well marked; (ii) shell ovate-conic, accuminate; (iii) aperture sub-ovate, lip simple; (iv) kidney with granulated lamellae; and (v) marginal teeth with blunt spatula-shaped mesocones. The record of spermatophores for the genus is provided here for the first time.

Plicidentine in the oral fangs of parrotfish (Scarinae, Labriformes).

Parrotfish play important ecological roles in coral reef and seagrass communities across the globe. Their dentition is a fascinating object of study from an anatomical, functional and evolutionary point of view. Several species maintained non-interlocked dentition and browse on fleshy algae, while others evolved a characteristic beak-like structure made of a mass of coalesced teeth that they use to scrape or excavate food off hard limestone substrates. While parrotfish use their highly specialized marginal teeth to procure their food, they can also develop a series of large fangs that protrude from the upper jaw, and more rarely from the lower jaw. These peculiar fangs do not participate in the marginal dentition and their function remains unclear. Here we describe the morphology of these fangs and their developmental relationship to the rest of the oral dentition in the marbled parrotfish (Leptoscarus vaigiensis), the star-eye parrotfish (Calotomus carolinus), and the palenose parrotfish (Scarus psittacus). Through microtomographic and histological analyses, we show that some of these fangs display loosely folded plicidentine along their bases, a feature that has never been reported in parrotfish. Plicidentine is absent from the marginal teeth and is therefore exclusive to the fangs. Parrotfish fangs develop a particular type of simplexodont plicidentine with a pulpal infilling of alveolar bone at later stages of dental ontogeny. The occurrence of plicidentine and evidence of extensive tooth wear, and even breakage, lead us to conclude that the fangs undergo frequent mechanical stress, despite not being used to acquire food. This strong mechanical stress undergone by fangs could be linked either to forced contact with congeners or with the limestone substrate during feeding. Finally, we hypothesize that the presence of plicidentine in parrotfish is not derived from a labrid ancestor, but is probably a recently evolved trait in some parrotfish taxa, which may even have evolved convergently within this subfamily.

The new genus Aglaona: the first abyssal aglajid (Heterobranchia: Cephalaspidea: Aglajidae) with a description of two new species from the north-western Pacific Ocean

Abstract In this paper we describe the new genus Aglaona, the first abyssal genus of the family Aglajidae, comprising two new species: Aglaona rudmani sp. nov. from the Sea of Okhotsk (inhabiting a depth of 3206 m) and Aglaona valdesi sp. nov. from the Pacific slope of the Kuril Islands (at a depth of 3374–3580 m). For species descriptions and inference of relationships, we have followed an integrative approach, including molecular phylogenetic analyses based on four markers (COI, 16S, H3 and 28S) and a morphological analysis based on traditional anatomical dissections and scanning electron microscopy. The new genus is characterized by a well-developed radula with marginal teeth (2:1:0:1:2) and an internal bulloid shell with a wing-like parietal callus. External and internal morphology of Aglaonagen. nov. species is similar to that of the philinoid genus Laona (family Laonidae). Phylogenetic analyses support the inclusion of the new genus in the family Aglajidae, but its sister-relationships are unresolved. Our results suggest that Aglaonagen. nov. possesses several plesiomorphic characters, and that the reduction of shell and radula in Aglajidae occurred in parallel in different lineages.

The rhipidoglossan radula: Radular morphology and formation in Nerita litterata Gmelin, 1791 (Neritimorpha, Neritidae).

The rhipidoglossan radula, consisting of numerous teeth in each transverse row, is characteristic of phylogenetically distant groups of gastropods, including Vetigastropoda, Neritimorpha and 'lower' Heterobranchia. Previous studies have revealed the main patterns in the formation of the rhipidoglossan radula of vetigastropods, the main feature of which is the division of the formation zone into two horns, where marginal teeth are formed by a multilayered epithelium (odontoblasts). This work is devoted to the study of the formation of the rhipidoglossan radula of Nerita litterata using light and electron microscopy. The data obtained show that, despite the different external morphology of the radular sac of neritids and vetigastropods, the radular sac of N. litterata, like that of vetigastropods, is divided into two parts, in which the marginal teeth are similarly formed by odontoblasts located in more than one layer. It seems probable that this complex, three-dimensional structure of the formation zone is associated with a broad radula with numerous elongate marginal teeth and could be characteristic of other gastropods with this type of radula. Additional supporting rods located along the odontoblasts and consisting of vacuolated cells were first discovered in Nerita.

Genital anatomy, jaw and radula of Guladentiasubtussulcata (Helicoidea, Cepolidae), endemic to western Cuba.

This study provides the first data on the genital anatomy, jaw and radula of Guladentiasubtussulcata (L. Pfeiffer, 1863). The auxiliary copulatory organ of this species is very peculiar, similar to that of Jeanneretia L. Pfeiffer, 1877, and different from that of other cepolids. It consists of an elongate, pedunculate mucus gland inserted apically on a muscular papilla and an atrial sac, all covered by a sheath. A sheath-like accessory gland is inserted at the base of the atrial sac. Another similarity with Jeanneretia is the presence of a fertilization pouch-spermatheca complex with a single exposed spermatheca. Like Jeanneretia, G.subtussulcata has an oxygnath, highly arched jaw with slight striae over the entire surface and a broad, well-developed median projection. The radula has triangular and monocuspid central and lateral teeth (the central teeth are smaller than the rest). The marginal teeth are multicuspid with the mesocone and ectocones smaller than the endocones. The similar structures of the auxiliary copulatory organ (without dart sac) and spermatheca (simple) strongly suggest that G.subtussulcata and Jeanneretia spp. are closely related. As such, it remains to be decided whether Guladentia Clench & Aguayo, 1951 and Jeanneretia should continue to be treated as separate genera.