Anterior Shell Research Articles

Initial clinical experience of surface guided stereotactic radiation therapy with open-face mask immobilization for improving setup accuracy: a retrospective study

PurposeTo propose a specific surface guided stereotactic radiotherapy (SRT) treatment procedure with open-face mask immobilization and evaluate the initial clinical experience in improving setup accuracy.Methods and materialsThe treatment records of 48 SRT patients with head lesions were retrospectively analyzed. For each patient, head immobilization was achieved with a double-shell open-face mask. The anterior shell was left open to expose the forehead, nose, eyes and cheekbones. The exposed facial area was used as region-of-interest for surface tracking by AlignRT (VisionRT Inc, UK). The posterior shell provided a sturdy and personalized headrest. Patient initial setup was guided by 6DoF real-time deltas (RTD) using the reference surface obtained from the skin contour delineated on the planning CT images. The endpoint of initial setup was 1 mm in translational RTD and 1 degree in rotational RTD. CBCT guidance was performed to derive the initial setup errors, and couch shifts for setup correction were applied prior to treatment delivery. CBCT couch shifts, AlignRT RTD values, repositioning rate and setup time were analyzed.ResultsThe absolute values of median (maximal) CBCT couch shifts were 0.4 (1.3) mm in VRT, 0.1 (2.5) mm in LNG, 0.2 (1.6) mm in LAT, 0.1(1.2) degree in YAW, 0.2 (1.4) degree in PITCH and 0.1(1.3) degree in ROLL. The couch shifts and AlignRT RTD values exhibited highly agreement except in VRT and PITCH (p value < 0.01), of which the differences were as small as negligible. We did not find any case of patient repositioning that was due to out-of-tolerance setup errors, i.e., 3 mm and 2 degree. The surface guided setup time ranged from 52 to 174 s, and the mean and median time was 97.72 s and 94 s respectively.ConclusionsThe proposed surface guided SRT procedure with open-face mask immobilization is a step forward in improving patient comfort and positioning accuracy in the same process. Minimized initial setup errors and repositioning rate had been achieved with reasonably efficiency for routine clinical practice.

Ibandronate Suppresses Changes in Apatite Orientation and Young's Modulus Caused by Estrogen Deficiency in Rat Vertebrae

Bone material quality is important for evaluating the mechanical integrity of diseased and/or medically treated bones. However, compared to the knowledge accumulated regarding changes in bone mass, our understanding of the quality of bone material is lacking. In this study, we clarified the changes in bone material quality mainly characterized by the preferential orientation of the apatite c-axis associated with estrogen deficiency-induced osteoporosis, and their prevention using ibandronate (IBN), a nitrogen-containing bisphosphonate. IBN effectively prevented bone loss and degradation of whole bone strength in a dose-dependent manner. The estrogen-deficient condition abnormally increased the degree of apatite orientation along the craniocaudal axis in which principal stress is applied; IBN at higher doses played a role in maintaining the normal orientation of apatite but not at lower doses. The bone size-independent Young's modulus along the craniocaudal axis of the anterior cortical shell of the vertebra showed a significant and positive correlation with apatite orientation; therefore, the craniocaudal Young’s modulus abnormally increased under estrogen-deficient conditions, despite a significant decrease in volumetric bone mineral density. However, the abnormal increase in craniocaudal Young's modulus did not compensate for the degradation of whole bone mechanical properties due to the bone loss. In conclusion, it was clarified that changes in the material quality, which are hidden in bone mass evaluation, occur with estrogen deficiency-induced osteoporosis and IBN treatment. Here, IBN was shown to be a beneficial drug that suppresses abnormal changes in bone mechanical integrity caused by estrogen deficiency at both the whole bone and material levels.

Qingjianglepas from the Qingjiang biota, an evolutionary dead-end of Cambrian helcionelloid mollusks?

A minute limpet-shaped shell, Qingjianglepas elegans n. gen. n. sp., is reported from the 518 million-year-old Qingjiang biota in Hubei, China. The new shell exhibits a typical limpet morphology with a shell sculpture of strongly developed radial ribs, an anterior shell fold, and distinctive shell shape shift. Feature combinations such as in Qingjianglepas are unique among Cambrian mollusk assemblages, but strikingly resemble that of some modern fissurellids (keyhole and slit limpets; Vetigastropoda). The biological affinity of Qingjianglepas is discussed, but temporarily remains uncertain. Regardless, the heavily sculptured and limpet-shaped Qingjianglepas represents a previously unrecognized shell form, and hence significantly extends the morphological diversity of Cambrian mollusks. The abrupt ontogenetic change in shell morphology suggests that Qingjianglepas might change microhabitat throughout the growth of the animal. This study reveals that the phenomenon of limpetization occurred within early Cambrian total-group conchiferans. Furthermore, Qingjianglepas might represent an evolutionary dead-end in course of helcionelloid mollusk evolution, which marks the end of the Cambrian explosion of animals at the beginning of Cambrian Series 2.

Sex, shells, and weaponry: coercive reproductive tactics in the painted turtle, Chrysemys picta

Males and females have divergent reproductive interests arising from their unequal investments in offspring. This sexual conflict drives an antagonistic arms race that influences sex-specific reproductive success. Alternative reproductive tactics are expected in long-lived species for which the reproductive strategy that maximizes mating success could differ across body sizes. The mating strategy of the painted turtle (Chrysemys picta) has been characterized as an elaborate and amiable male courtship display during which males use their elongate foreclaws to stroke females, coupled with female mate choice. Contrary to this long-held understanding, in situ field observations and experimental trials from our long-term study in Algonquin Provincial Park, Canada, demonstrate that males also exhibit an alternative, coercive mating strategy. Males are equipped with sexually size dimorphic tomiodonts, tooth-like cusps of the beak, as well as a weaponized anterior shell, with which they wound the head and neck of females. Behavioral trials during the breeding periods showed that male reproductive tactics shift from courtship (foreclaw display) to coercion (striking, biting, and forced submergence) across ontogeny, and male size predicts the occurrence and frequency of coercive behavior. We found phenotype-behavior matching whereby small males invest in putatively ornamental foreclaws used for courtship and large males invest in weaponry for coercion, challenging existing knowledge of this well-studied species. As a group with a long evolutionary history and varied mating systems, Testudines are a particularly interesting taxon in which to ask questions about mating system evolution. Alternative reproductive tactics are hypothesized for long-lived species. We quantified a shift from apparent courtship to coercive tactics during the reproductive lifespan of a well-studied freshwater turtle. Male painted turtles (Chrysemys picta) have sexual weapons that are used to promote female acquiescence. Using behavioral trials with turtles from a long-term study population, we demonstrate that males match their morphology (ornament/weapons) to reproductive behavior (courtship/coercion) as their reproductive tactics shift. Our findings hint at the behavioral complexity of aquatic turtles, a challenging and often-overlooked group in behavioral studies.

Phylogenetic relationships of Asian freshwater Mytiloidea (Bivalvia): a morphological and genetic comparison of Sinomytilus harmandi, Limnoperna fortunei and Septifer bilocularis

ABSTRACTThe Mekong River endemic Sinomytilus harmandi possesses an internal anterior shell septum. It is thus superficially similar to the marine representatives of the, as currently defined, Septiferinae (Mytilidae) although species of the latter possess an anterior adductor muscle located between their septa and are characterised by accessory posterior adductor muscles, both of which are absent in S. harmandi. This study demonstrates that S. harmandi is monophyletic with the only other, similarly native Asian, freshwater mytiloid, Limnoperna fortunei, based on the phylogenetic tree herein presented. Asian freshwaters thus seem to have been colonised by the Mytilidae relatively recently and on two occasions from a common ancestor also associated with representatives of the Lithophaginae, as currently defined. The common presence of an anterior septum in S. harmandi and species of the Septiferinae, as currently recognised, is thus the result of convergence as is the anatomical similarity between S. harmandi and representatives of the Central European Dreissenidae (Heterodonta), which also possess an anterior shell septum.

Evaluation of a Functional Brace in ACL-Deficient Subjects Measuring Ground Reaction Forces and Contact Pressure: A Pilot Study

ABSTRACT Introduction An ideal functional brace for anterior cruciate ligament-deficient (ACLD) patients should control anterior movement of the tibia and simultaneously decrease the effects of ground reaction shearing force. The current study was aimed to compare the interface pressure between the anterior shell of a functional brace and proximal of tibia in both sound and ACLD limbs, and to assess the effect of using functional brace on the symmetry of vertical and anteroposterior components of ground reaction force and impulse of ground reaction force during level walking. Methods Seven unilateral ACLD men participated in this study. The interface pressure between the anterior shell and proximal of the tibia and ground reaction force was recorded by means of Novel Pliance X and Kistler force platform, respectively. Wilcoxon ranked-sign test and factor analysis repeated measure analysis of variance were used to analyze data. Results The use of functional brace had no significant effect on interface pressure and peak points of the ground reaction force. By use of a functional brace, the valley and the impulse of the vertical component of ground reaction force on ACLD limb increased significantly (P &lt; 0.05) and also improved limb symmetry of all parameters. The interface pressure was greater at distal contact points of the shell, which are at the middle level of the tibia crest. Conclusions The results suggest that functional brace could not apply force on proximal tibia especially at ACLD limb and therefore could not normalize vertical component of ground reaction force during level walking.

Brachiopod shell thickness links environment and evolution

AbstractWhile it is well established that the shapes and sizes of shells are strongly phylogenetically controlled, little is known about the phylogenetic constraints on shell thickness. Yet, shell thickness is likely to be sensitive to environmental fluctuations and has the potential to illuminate environmental perturbations through deep time. Here we systematically quantify the thickness of the anterior brachiopod shell which protects the filtration chamber and is thus considered functionally homologous across higher taxa of brachiopods. Our data come from 66 genera and 10 different orders and shows well‐defined upper and lower boundaries of anterior shell thickness. For Ordovician and Silurian brachiopods we find significant order‐level differences and a trend of increasing shell thickness with water depth. Modern (Cenozoic) brachiopods, by comparison, fall into the lower half of observed shell thicknesses. Among Ordovician–Silurian brachiopods, older stocks commonly have thicker shells, and thick‐shelled taxa contributed more prominently to the Great Ordovician Biodiversification but suffered more severely during the Late Ordovician Mass Extinction. Our data highlight a significant reduction in maximum and minimum shell thickness following the Late Ordovician mass extinction. This points towards stronger selection pressure for energy‐efficient shell secretion during times of crisis.

Shell Interior of Semiplanella carinthica Sarytcheva et Legrand-Blain (Brachiopoda, Productida)

The interior of the dorsal valve of Semiplanella carinthica Sarytcheva et Legrand-Blain, 1977 is described. The location of the bases of brachial loops and adductor muscles is reconstructed. The unusual arrangement of the adductor scars and brachial loops developed in the result of their rotation that was caused by a strong torsion of the shell and necessity to raise the anterior shell margin over the valve bottom. Similarly structured brachial loops and partly cardinal process is known for Beleutella Litvinovich, 1967 and possibly Talasoproductus Litvinovich et Vorontsova, 1983. These three genera are suggested to be united into a new tribe Semiplanellini tribe nov. of the subfamily Gigantoproductinae.

Ancestral morphology of crown-group molluscs revealed by a new Ordovician stem aculiferan.

Exceptionally preserved fossils provide crucial insights into extinct body plans and organismal evolution. Molluscs, one of the most disparate animal phyla, radiated rapidly during the early Cambrian period (approximately 535-520 million years ago (Ma)). The problematic fossil taxa Halkieria and Orthrozanclus (grouped in Sachitida) have been assigned variously to stem-group annelids, brachiopods, stem-group molluscs or stem-group aculiferans (Polyplacophora and Aplacophora), but their affinities have remained controversial owing to a lack of preserved diagnostic characters. Here we describe a new early sachitid, Calvapilosa kroegeri gen. et sp. nov. from the Fezouata biota of Morocco (Early Ordovician epoch, around 478 Ma). The new taxon is characterized by the presence of a single large anterior shell plate and polystichous radula bearing a median tooth and several lateral and uncinal teeth in more than 125 rows. Its flattened body is covered by hollow spinose sclerites, and a smooth, ventral girdle flanks an extensive mantle cavity. Phylogenetic analyses resolve C. kroegeri as a stem-group aculiferan together with other single-plated forms such as Maikhanella (Siphogonuchites) and Orthrozanclus; Halkieria is recovered closer to the aculiferan crown. These genera document the stepwise evolution of the aculiferan body plan from forms with a single, almost conchiferan-like shell through two-plated taxa such as Halkieria, to the eight-plated crown-group aculiferans. C. kroegeri therefore provides key evidence concerning the long debate about the crown molluscan affinities of sachitids. This new discovery strongly suggests that the possession of only a single calcareous shell plate and the presence of unmineralised sclerites are plesiomorphic (an ancestral trait) for the molluscan crown.

One clinic's experience with carbon fiber orthoses in neuromuscular disease.

The purpose of this study was to summarize our experience with off-the-shelf anterior shell carbon fiber ankle-foot orthoses (CFAFOs) prescribed to adult neuromuscular patients in an outpatient clinic. We studied ambulatory patients who were seen in Muscular Dystrophy Association or amyotrophic lateral sclerosis clinics between 2011 and 2014 and prescribed anterior shell CFAFOs. Charts were reviewed with attention to diagnosis, satisfaction with use, and reasons for acceptance or rejection. We included individuals who were currently using AFOs and those being prescribed AFOs for the first time. We were especially interested in reasons for acceptance or rejection of the orthosis. Two hundred eighty-three charts were reviewed. Of these, 109 of 123 (89%) patients were satisfied or extremely satisfied with the anterior shell CFAFOs, including 38 who had previously used other styles. Anterior shell CFAFOs should be considered for most neuromuscular patients with distal leg weakness. Muscle Nerve 55: 202-205, 2017.

Morphological and genetic identification of freshwater Dreissenid Mussels: Dreissena polymorpha (Pallas, 1771), and D. rostriformis bugensis Andrusov, 1897 (Dreissenidae, Bivalvia)

Dreissenids display a high diversity of shell morphology. Taxonomic keys based on shell morphology are not always able to differentiate these species with confidence. In such cases, genetic markers are useful in addition to morphological features. Typical and atypical dreissenid individuals are analyzed in this study. It is demonstrated that the position of ventrolateral angle at the anterior part of a valve (3–5 mm from the anterior shell edge) is a reliable diagnostic feature for atypical D. polymorpha and D. r. bugensis.

Poster 282 A Temporary Trial of an Anterior Shell to Evaluate Gait Abnormalities in a Patient Not Responsive to a Semi-rigid AFO: A Case Report

Poster 282 A Temporary Trial of an Anterior Shell to Evaluate Gait Abnormalities in a Patient Not Responsive to a Semi-rigid AFO: A Case Report

Quantitative analysis of intraspecific variations in the carbon and oxygen isotope compositions of the modern cool-temperate brachiopod Terebratulina crossei

This study unravels intraspecific variations in the carbon isotope (δ13C) and oxygen isotope (δ18O) compositions of shells of the modern cool-temperate brachiopod Terebratulina crossei collected at a water depth of 70m in Otsuchi Bay, northeastern Honshu, Japan. Brachiopod shells have been used as proxies of the δ13C values of dissolved inorganic carbon (DIC) (δ13CDIC) and seawater temperature/δ18O (δ18OSW) values to reconstruct the evolution of Phanerozoic oceans. To identify more reliable shell portions as the proxies, we conducted a rigorous time-series comparison of δ13C and δ18O values between the brachiopod shells and calcite precipitated in isotopic equilibrium with ambient seawater (equilibrium calcite) (δ13CEC and δ18OEC values, respectively). Samples were collected from the outer and inner surfaces of the secondary shell layer along the maximum growth axis (ontogenetic-series and inner-series samples, respectively). The ontogenetic-series δ13C values, which showed regular annual and irregular non-annual cycles, partly fell in but were mostly less than the range of the δ13CEC values. The δ13C cycles were often associated with one or two minor negative peaks. The peaks were likely resulted from an increased incorporation of respiration-derived 12C due to elevated metabolic activity during spawning. The ontogenetic-series δ18O values showed distinct seasonal variations and were mostly within the range of δ18OEC values. The amplitude of the δ18O profiles was relatively large during the younger fast-growth stage, and decreased during the senescent slow-growth stage. The inner-series δ13C and δ18O values of individual shells varied within narrow ranges. The inner-series δ13C values were close to the minimum δ13CEC values. The inner-series δ18O values were in the upper range of the δ18OEC values. Kinetic isotope fractionation effects were evident, but its degree varied among different shells. We identified the shell portions reliably recording past ocean environments. The best estimates of annual average δ13CDIC values were obtained from ontogenetic-series δ13C values near the anterior shell edge and from inner-series δ13C values; those of the annual average seawater temperature were obtained from ontogenetic-series δ18O values from the entire transect and from the fast-growth stage.

Brachiopod shell spiral deviations (SSD): Implications for trace element proxies

The importance of brachiopod shells as archives of past environmental changes, via chemical proxies (isotopes and trace elements), will increase significantly if the age of specimens can be determined accurately. Here, we evaluate the interpretation of spiral shell deviations throughout the ontogeny of the modern brachiopod species Laqueus rubellus collected from Sagami Bay (Japan), in combination with high-resolution biogeochemistry. The determination of spiral maxima and minima indicates that there is a different growth rate for ventral and dorsal valves, as well as for juvenile and adult specimens, and that the anterior shell regions provide a more accurate record of shell growth. The combination of trace element proxies (P/Ca and Mg/Ca) with shell spiral deviations indicates that the maxima represent prominent periods of shell growth that occurs during the beginning of the autumn. By counting the maxima on dorsal valves of fully mature specimens, these specimens can record shell growth up to 6–7years, which is confirmed by independent morphological and isotopic studies in the same brachiopod species. The integration of statistical measurements of shell morphologies with chemical measurements represents an innovative methodology for specimen-age determinations in brachiopods, and provides a better understanding of trace element proxies. Overall, the application of this approach to fossil brachiopods may open a new avenue for paleoseasonality and paleoceanography studies.

Two new species of Waldo Nicol, 1966 from sub-Antarctic waters (Bivalvia: Galeommatoidea)

Two new sub-Antarctic Waldo species (Bivalvia) are described: Waldo digitatus and W. paucitentaculatus. Waldo digitatus has a large, elongate–oval shell, with a short, horizontal dorsal margin, the valves showing a wide ventral gape, well separated from the anterior gape, and faint radial sculpture, fading toward shell margin. In addition, in this species the inhalant-pedal aperture is flanked by 5–15 pairs of tentacles. Waldo paucitentaculatus has a small, triangular–oval shell, with anterior and posterior half of dorsal margin long, sloping gently at similar angles, the anterior and ventral shell gapes coalesce to form a single, narrow and elongated gape, and radial sculpture well-marked and visible from beaks to ventral margin. Another distinctive character is the presence of only 1 or 2 pairs of tentacles bordering the siphonal-pedal aperture. Both species were found living as epibionts on the heart sea urchin Abatus cavernosus: W. digitatus is restricted to the perioral area and W. paucitentaculatus is more widely distributed, mainly on the oral surface.

First Report of Anterior Pallial Tentacles in Solen dactylus (Bivalvia: Solenidae) from the Northern Persian Gulf, Iran

Solenidae are deep burrowing bivalves inhabiting intertidal and shallow sub-tidal soft bottom sediments mostly in tropical and sub-tropical areas. Solen dactylus has a restricted distribution within the Indian Ocean. Solen dactylus is frequently found on the sandy-muddy coast of the northern Persian Gulf, Iran. Specimens of S. dactylus were collected since 2006 from Bandar Abbas to study their biology and ecology. During these studies, an unexpected pair of anterior pallial tentacles at the dorsal end of the anterior pallial crest of the mantle was found. In the tentacles, two kinds of epithelial cells (pyramidal and vacuolated) and fibres (radial and longitudinal), and a branch of the pallial nerve located in the centre of a haemocoel, were determined. A possible coherence of a furrow parallel to the anterior shell margin with the presence of anterior pallial tentacles is discussed. All species with long anterior pallial tentacles have anterior shell furrows. Anterior pallial tentacles were found in 10 species of Solenidae from Asia to the Middle East and Europe. The function of the tentacles is unknown. However, more species need to be examined for anterior pallial tentacles and anterior shell furrows to determine if they reflect a common evolutionary history or ecology.

Carbon- and oxygen-isotope compositions of a modern deep-water brachiopod Campagea japonica collected off Aguni-jima, Central Ryukyu Islands, southwestern Japan

We present carbon- and oxygen-isotope compositions in a shell (δ13CS and δ18OS, respectively) of a modern brachiopod Campagea japonica collected at a water depth of 606 m off Aguni-jima, Central Ryukyu Islands, southwestern Japan. The δ13CS and δ18OS profiles of the outermost portions of the secondary shell layer along the axis of shell growth do not display significant seasonal variations. The δ13CS values display a gradual decrease with growth, whereas the δ18OS values are nearly constant. The δ13CS and δ18OS values along a particular growth line and from the inner shell surface are rather constant. The δ13CS values near the posterior shell edge of the ontogenetic series and the δ18OS values near the anterior shell edge of the inner series fall within the ranges of δ13C and δ18O values of calcite in equilibrium with ambient seawater (equilibrium calcite) (δ13CEC and δ18OEC, respectively). Therefore, they are the best portions to use as proxies of δ13C values of dissolved inorganic carbon (δ13ODIC) and temperature and/or δ18O values of seawater (δ18OSW), respectively. The δ13CS values of the ontogenetic series near the anterior shell edge and the entire isochronous and inner series display the smallest decrease (less than ~0.2‰) compared with the δ13CEC values. The δ18OS values of the entire ontogenetic series and an interior part of the inner series are slightly greater (less than ~0.3‰) than the δ18OEC values. Thus, these portions can be used as paleoenvironmental proxies if appropriate corrections are made. A significant positive correlation is recognized between the δ13CS and δ18OS values for the ontogenetic-series samples, which can be ascribed to a kinetic isotope effect. A metabolic isotope effect is not evident for the δ18OS values in these samples. Our study provides useful information for the appropriate selection of brachiopod taxa and shell portions that reflect isotopic composition of ambient seawater for paleoenvironmental studies.

Opertochasma somaensisn. sp. (Bivalvia: Pholadidae) from the Upper Jurassic in Japan: a perspective on pholadoidean early evolution

The evolutionary history of the major boring-bivalve superfamily Pholadoidea remains unclear.Opertochasma somaensisn. sp., preserved in situ in fossilized wood from upper Kimmeridgian to lower Tithonian strata within the Upper Jurassic shallow marine Nakanosawa Formation, northeast Japan, is described. This new species represents one of the oldest body fossils of pholadoidean boring-bivalves and the first fossil record from the Jurassic in the circum-Pacific regions. The authochthonous occurrence in fossilized wood, the presence of microscopic file-like sculpture on the anterior shell slope, the short clavate burrow, and other shell features demonstrate thatO. somaensisn. sp. was a filter-feeding, obligate wood-borer with anterior-boring locomotion, and also that the complex shell morphology unique to Pholadoidea was established by the Late Jurassic. The documentation of the new species and taxonomic review on the Jurassic species previously described, show that the superfamily Pholadoidea was widely distributed along the Northern Hemisphere middle latitudes in the latest Jurassic. The Pholadoidea likely evolved by exploiting woody substrata which had become abundant during the Late Jurassic with floral diversification in the middle latitudes. It is notable that the xylophagous mode of life, referable to modern Teredinidae and Xylophagaidae, was most probably established in the Jurassic and provided an important background for the establishment of chemosynthesis-based, sunken wood-associated communities.

An unusual Late Triassic nuculid bivalve with divaricate shell ornamentation, and the evolutionary history of oblique ribs in Triassic bivalves

The new nuculid bivalveTrigonucula(Gonionucula)aciloidesnew subgenus and species from the upper Triassic Nayband Formation of Central Iran is described.Gonionuculadiffers fromTrigonuculas.s. by the presence of oblique ribs, which either deviate from a concentric pattern at the anterior shell part, or, as in the newly described type species, consist of a complex pattern of chevron-like ribs on the central part of the flank, plus an additional set of opisthocline to more or less acline ribs on posterior part of the flank. The oblique ribs ofGonionuculaprobably aided energy-efficient burrowing, which was advantageous in competing for food resources with less efficiently burrowing detritus feeders. The number of burrowing bivalve species with oblique ribs generally rose towards the end of the Triassic, which probably reflects increasing competition at a time when most niches were re-occupied after the end-Permian mass extinction event. The fact that oblique ribs were rare in Paleozoic bivalves suggests that the level of competition was higher in post-Paleozoic biota, which is in accordance with a general increase in metabolic rates, predation pressure, and ecospace occupation in the course of the Mesozoic.

An early Daonella from the Middle Anisian of Guangxi, southwestern China, and its phylogenetical significance

The late Middle Anisian Daonella fengshanensis sp. nov. from the upper part of the Lower Member of the Banna Formation near Jinya in northwestern Guangxi, southwestern China, represents the earliest appearance of Daonella in this region. With regard to stratigraphical occurrence as well as morphological features the new species is in a transitional position between Enteropleura and more derived species of Daonella. The new species is an early representative of the genus Daonella and regarded as phylogenetically being near the genus’ origin. It is characterised by a small posterior auricle similar to Enteropleura and flat-topped radial ribs resembling later species of Daonella. Its anterior shell sector is large. The shell sculpture of juvenile stages closely resembles both Daonella and Enteropleura, supporting the hypothesis that Daonella may have evolved from Enteropleura.