Zoology最新文献

{"title":"Data collected by citizen scientists reveal the role of climate and phylogeny on the frequency of shelter types used by frogs across the Americas","authors":"Lucas Rodriguez Forti ,&nbsp;Mariana Retuci Pontes ,&nbsp;Guilherme Augusto-Alves ,&nbsp;Allana Martins ,&nbsp;Fábio Hepp ,&nbsp;Judit K. Szabo","doi":"10.1016/j.zool.2022.126052","DOIUrl":"10.1016/j.zool.2022.126052","url":null,"abstract":"<div><p><span><span>Shelters are microhabitats where animals rest and hide. These microhabitats can be used from short daily periods to long-term </span>estivation<span> or hibernation. Environmental conditions and the phenotypical characteristics of the animal drive habitat selection in relation to shelters. Based on this, climate regions and phylogeny are expected to affect the use of different shelter types. Although shelters are yet to be described for most anuran species, a variety of microhabitats have already been reported as shelter-sites, including dense vegetation, rock crevices, and holes in the ground. In this study, we evaluated photos of frogs for sheltering behaviour from 29 countries in the Americas deposited on the popular citizen-science platform, iNaturalist. We compared the frequency of use of different shelter types identified on the photos among different climate regions and anuran families, also testing possible phylogenetic signals. We identified 11,133 photographs of 378 frog species showing individuals hiding in shelters or in a resting position. We classified observations into 10 shelter types, with </span></span><em>live vegetation</em> (24.7 %) being the most commonly recorded natural shelter, followed by <em>hole in the ground</em> (11.4 %) and <em>tree trunk</em> (11.1 %). The use of different shelter types varied between arid and humid climates, and also among different anuran families. We found strong phylogenetic signal for three shelter types (<em>hole in the ground</em>, <em>live vegetation</em>, and <em>water</em>) and the differences in shelter use among taxa suggest a relation with body characteristics. Approximately 47 % of observations of threatened and near threatened species were in <em>hole in the ground</em>, while <em>artificial habitat</em><span> represented only 3.6 % of the observations in this group. The daily pattern of shelter use corroborated the nocturnal activity of most species. Our findings also expanded the description of shelter sites for 330 species that had no published information on this behaviour. This study contributes to our current knowledge about animal behaviour and highlights the use of citizen science as an effective approach to understand the natural history of amphibians at a large scale.</span></p></div>","PeriodicalId":49330,"journal":{"name":"Zoology","volume":"155 ","pages":"Article 126052"},"PeriodicalIF":2.0,"publicationDate":"2022-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"10571076","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Phalanx morphology in salamanders: A reflection of microhabitat use, life cycle or evolutionary constraints?","authors":"María Laura Ponssa ,&nbsp;Jessica Fratani ,&nbsp;J. Sebastián Barrionuevo","doi":"10.1016/j.zool.2022.126040","DOIUrl":"10.1016/j.zool.2022.126040","url":null,"abstract":"<div><p><span>Morphological patterns are modeled by the interaction of functional, phylogenetic, ecological, and/or developmental constraints. In addition, the evolution of life cycle complexity can favor phenotypic diversity; however, the correlation between stages of development may constrain the evolution of some organs. </span>Salamanders<span> present microhabitat<span> and life cycle diversity, providing an excellent framework for testing how these factors constrain phenotypic evolution. We reconstructed the morphological evolution of the terminal phalanx using a sample of 60 extinct and living species of salamanders. Using a geometric morphometric approach combined with comparative analyses, we further investigated the impact of phylogenetic, ecological, and/or life cycle factors on the shape of the terminal phalanx. We find that the phylogeny has some influence in determining the dorsal shape of the phalanges; whereas a relationship between microhabitat or life cycle and the dorsal and lateral shapes of the phalanx was not observed in the analyzed species. The allometric pattern found in the phalanx shape implies that small phalanges are more curved and with more truncated end than bigger phalanges. The evolutionary rate of phalanx shape was higher in the semiaquatic species, and the morphological disparity was significantly higher on biphasic groups. These results contradict the hypothesis that a complex life cycle constrains body shape. Finally, the phalanx shape of the salamander remains quite conserved from the Mesozoic. This configuration would allow them to occur in the different microhabitats occupied by the salamander lineages.</span></span></p></div>","PeriodicalId":49330,"journal":{"name":"Zoology","volume":"154 ","pages":"Article 126040"},"PeriodicalIF":2.0,"publicationDate":"2022-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"40616210","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Morphological comparison of the cranial movement apparatus in mudskippers (Gobiidae: Oxudercinae)","authors":"Loi X. Tran ,&nbsp;Thoa T.K. Nguyen ,&nbsp;Toan T. Vo","doi":"10.1016/j.zool.2022.126042","DOIUrl":"10.1016/j.zool.2022.126042","url":null,"abstract":"<div><p>Possession of the neck allows vertebrates to move the head independently from the trunk. Fish do not have the neck and thus the cranial mobility could be limited. Oxudercine gobies show full range of habitat transition from aquatic to terrestrial environments and exhibit flexible cranial movement, yet the cranium-movement apparatus is little known. In this study, we investigated the anatomy of the structure of the eight oxudercine gobies, <em>Oxuderces nexipinnis</em>, <em>Parapocryptes serperaster</em>, <em>Pseudapocryptes elongatus</em>, <em>Scartelaos histophorus</em>, <em>Boleophthalmus boddarti</em>, <span><em>Periophthalmus</em><em> chrysospilos</em></span>, <em>Periophthalmodon schlosseri</em>, and <em>Periophthalmodon septemradiatus</em>. These species share similarities in the specialized features of the craniovertebral joint and the epaxials attaching onto different locations of the neurocranium. On the other hand, large space between the ventral portions of the craniovertebral joint only occurs in <em>O. nexipinnis</em>, <em>Pd. elongatus</em>, <em>Pn. schlosseri</em> and <em>Pn. septemradiatus</em>. Hypaxials are hypertrophied at the insertion point and attach more anteriorly onto the ventral side of the neurocranium in <em>B. boddarti</em>, <em>O. nexipinnis</em>, <em>Pa. serperaster</em>, <em>Pd. elongatus</em>, and <em>S. histophorus</em>, whereas the muscles are small and attach posteriorly in the remaining species. There were significant differences in the area occupancy ratio of the post-cranial neural spines, the lever arm ratio of the cranial rotation, and the angle between the horizontal plane and the plane through the craniovertebral joint among the species. The cranial depression presumably facilitates grazing of oxudercine gobies in their early stage of terrestrial transition, whereas the cranial elevation parameters are contradictory to the terrestrial gradient. The cranium-movement morphometrics partially agree with the phylogeny.</p></div>","PeriodicalId":49330,"journal":{"name":"Zoology","volume":"154 ","pages":"Article 126042"},"PeriodicalIF":2.0,"publicationDate":"2022-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"40424234","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Quantitative analysis of vocalisation types in male common cuckoos’ \"gowk\" call complex","authors":"Csaba Moskát ,&nbsp;Márk E. Hauber","doi":"10.1016/j.zool.2022.126043","DOIUrl":"10.1016/j.zool.2022.126043","url":null,"abstract":"<div><p>Acoustic communication of animals often contains two types of vocalizations: loud sounds for long-range and soft sounds for short-range signalling. Brood parasitic common cuckoos (<em>Cuculus canorus</em>) are suitable study objects for research on acoustic signalling as they have a simple acoustic repertoire, of which the loud territorial advertisement calls of males, the “cu-coo”, is the most famous type. Although a distinct group of soft calls has also been reported in early naturalists’ works, no systematic studies compared them acoustically. Even the classification of these soft calls is lacking. Here we surveyed these neglected types of calls, and evaluated them through bioacustic analyses. Specifically, we compared the following soft calls: single gowk, guo, and the series of gowk calls. The advertisement call (“cu-coo”) was used as the referent for these comparisons. As the male’s gowk series call most typically contains 3–5 elements with decreasing volume (disappearing at the end), we compared the first two elements of this call. Our analyses revealed great acoustic similarities between three call types (gowk series call 1st note, gowk series call 2nd note, and single gowk call), and the distinctiveness of the other call type (guo) from this group. Structurally the gowk cannot be regarded as a separate call from a male’s gowk series call, and the only difference is that the series call contains a set of the gowk calls. Our classification of cuckoo calls offers the possibility for further research into their functional importance and communicative role in male-male or female-male social contexts.</p></div>","PeriodicalId":49330,"journal":{"name":"Zoology","volume":"154 ","pages":"Article 126043"},"PeriodicalIF":2.0,"publicationDate":"2022-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0944200622000447/pdfft?md5=ec306473b02e63bf5f2768031a2ae1ce&pid=1-s2.0-S0944200622000447-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"10164981","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Female energy dynamics in the southernmost fiddler crab: Mixed breeding strategy in Leptuca uruguayensis","authors":"Agustina Marciano ,&nbsp;Karine Delevati Colpo ,&nbsp;Claudia Clementina Boy ,&nbsp;Laura Susana López Greco","doi":"10.1016/j.zool.2022.126041","DOIUrl":"10.1016/j.zool.2022.126041","url":null,"abstract":"<div><p><span><span>At the south of its geographical distribution, the </span>fiddler crab </span><em>Leptuca uruguayensis</em><span> shows two population spawning events, with more than 65 % of the females being ovigerous. The aim of this study was to assess the energy dynamics in </span><em>L. uruguayensis</em><span> females to estimate how they mix the capital and the income breeding strategies in the first and second spawns of the short reproductive season. The relationship between the hepatosomatic (HIS) and gonadosomatic (GSI) indices was used to assess the contribution of the hepatopancreas<span> to ovary maturation, as indicative of the capital breeding strategy, whereas the feeding rate and the energy available in the food resource (sediment) were estimated to assess the importance of energy intake in ovary maturation, as indicative of the income breeding strategy. Before the first spawn, a significant negative relationship between the HSI<span> and GSI (p &lt; 0.001) and an increase of 28.2 % in the feeding rate were recorded. This suggests that the first spawn was mainly supported by energy reserves in the hepatopancreas, indicating that females used mostly the capital breeding strategy. After the first spawn, total lipid content in the hepatopancreas decreased by 33 %. On the days before the second spawn, the relationship between the HSI and GSI showed a negative but not significant (p = 0.125) trend, whereas the feeding rate increased even more. This suggests that the intense feeding activity provided the most important energetic source for ovary re-maturation, indicating that females used mostly the income breeding strategy. Also, in the second spawn, the GSI was 24.1% smaller, a fact that affected female fecundity and weight of the egg clutches, which were respectively 12 % and 11 % lower than in the first spawn. However, the energy supply allocated to each embryo was equivalent in both spawns. This study shows how </span></span></span><em>L. uruguayensis</em> females mixed the capital and income breeding strategies to take advantage of all available resources to produce two spawns in a short reproductive season.</p></div>","PeriodicalId":49330,"journal":{"name":"Zoology","volume":"154 ","pages":"Article 126041"},"PeriodicalIF":2.0,"publicationDate":"2022-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"40417607","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effects of acute temperature change on California moray prey manipulation and transport behavior","authors":"Wave I. Moretto,&nbsp;Allegra K. Stahl,&nbsp;Rita S. Mehta","doi":"10.1016/j.zool.2022.126030","DOIUrl":"10.1016/j.zool.2022.126030","url":null,"abstract":"<div><p>California moray eels, <em>Gymnothorax mordax</em>, are benthic predatory residents of southern California kelp forest ecosystems. California morays around Catalina Island move vertically through the water column to feed, exposing them to a wide range of temperatures. For a predatory fish, morays have a relatively large prey handling repertoire that enable them to manipulate their prey before swallowing. Prey manipulation behaviors include shaking, spinning, knotting, and ramming prey against other objects. Morays also have observable transport mechanics where they protract and retract their pharyngeal jaws to swallow prey. We examined prey manipulation and transport behaviors at four temperature treatments that simulated the range of environmental temperatures morays encounter in the wild. We hypothesized that higher temperatures will increase the prevalence, duration, and rate of whole body prey manipulation behaviors and decrease the duration of prey transport time. Previous temperature studies focused on fishes occupying intermediate trophic levels. Therefore, understanding how acute temperature affects feeding behavior of the California moray eel, an abundant predatory fish, is especially important, as changes in environmental temperature may have disproportionate effects in their marine community. Five morays were acutely exposed to 15, 18, 21, 24 °C temperatures and their subsequent feeding behaviors were filmed and quantified. Individuals were offered the same relative prey mass (15 %) in relation to their body mass throughout the study. We compared the number of times each prey manipulation behavior occurred, the mean time morays employed each behavior, and the rate (number of times per second) each behavior was performed across different temperatures. Our data demonstrates that absolute time spent knotting varies significantly across temperature. Knotting, often used to remove pieces from larger prey, was most frequent at 21 and 24 °C. The average duration of knotting also increased with temperature. The rates of prey manipulation behaviors did not vary significantly with temperature. Finally, transport behavior did not vary across treatments. Our study shows that knotting behavior in the California moray is responsive to environmental temperatures and that morays may be able to manipulate larger prey in warmer waters. These behavioral data may have important implications for predator-prey relationships under dynamic and future ocean conditions.</p></div>","PeriodicalId":49330,"journal":{"name":"Zoology","volume":"154 ","pages":"Article 126030"},"PeriodicalIF":2.0,"publicationDate":"2022-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0944200622000319/pdfft?md5=747f1823a6b84ffdc30b0a81515efa6d&pid=1-s2.0-S0944200622000319-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"40559206","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Sexual dimorphism and allometry in malacophagus snakes (Dipsadidae: Dipsadinae)","authors":"Marina Meireles dos Santos ,&nbsp;Julia Klaczko ,&nbsp;Ana Lúcia da Costa Prudente","doi":"10.1016/j.zool.2022.126026","DOIUrl":"10.1016/j.zool.2022.126026","url":null,"abstract":"<div><p><span>Sexual dimorphism in snakes is generally described in association with body or tail size and scale counts, with relatively few studies addressing intrasexual divergence in the skull. Here, we analyzed sexual dimorphism in the size and shape of skull and body in three malacophagous dipsadine snakes, </span><em>Dipsas mikanii</em>, <em>Dipsas neuwiedi</em> and <em>Dipsas turgida</em>, as well as allometric effect on these components. We used linear and geometric analysis to assess: (1) if there is sexual dimorphism in cranial components; (2) if there are differences between the sexes regarding body and tail size, number of ventral and subcaudal scales; (3) whether there is covariation between cranial components and body size; (4) if there are changes in cranial shape associated with increased size; and (5) whether there is an allometric relationship between body and tail size. Our results showed that all three species are dimorphic in cranial shape and size (except <em>D. turgida</em><span> for cranial size), with females having longer and thinner skulls than males. In the three species, the female skull was negatively allometric, whereas the male skull was isometric. Allometry related to cranial shape was significant only in males of </span><em>D. turgida</em>, which showed greater snout robustness and eye size associated with enlargement of the skull. Females of <em>D. mikanii</em> and <em>D. neuwiedi</em> were significantly larger than males. Only males of <em>D. neuwiedi</em> showed positive allometry for the tail, while dimorphism related to scale counts followed the pattern found in most snakes, with females having a greater number of ventrals and males subcaudals (except <em>D. neuwiedi</em><span> in the latter case). Based on our results, we hypothesize that patterns of sexual dimorphism and skull allometry in malacophagous snakes may be explained both by aspects related to diet and reproduction. Meanwhile, patterns associated with body size reflect advantages related to fecundity favoring greater reproductive success of females.</span></p></div>","PeriodicalId":49330,"journal":{"name":"Zoology","volume":"153 ","pages":"Article 126026"},"PeriodicalIF":2.0,"publicationDate":"2022-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"40400048","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Range-wide variation in grey seal (Halichoerus grypus) skull morphology","authors":"Anders Galatius ,&nbsp;Michelle Strecker Svendsen ,&nbsp;Dolores Messer ,&nbsp;Mia Valtonen ,&nbsp;Michael McGowen ,&nbsp;Richard Sabin ,&nbsp;Vedrana Andersen Dahl ,&nbsp;Anders Bjorholm Dahl ,&nbsp;Morten Tange Olsen","doi":"10.1016/j.zool.2022.126023","DOIUrl":"10.1016/j.zool.2022.126023","url":null,"abstract":"<div><p>The large interspecific variation in marine mammal skull and dental morphology reflects ecological specialisations to foraging and communication. At the intraspecific level, the drivers of skull shape variation are less well understood, having implications for identifying putative local foraging adaptations and delineating populations and subspecies for taxonomy, systematics, management and conservation. Here, we assess the range-wide intraspecific variation in 71 grey seal skulls by 3D surface scanning, collection of cranial landmarks and geometric morphometric analysis. We find that skull shape differs slightly between populations in the Northwest Atlantic, Northeast Atlantic and Baltic Sea. However, there was a large shape overlap between populations and variation was substantially larger among animals within populations than between. We hypothesize that this pattern of intraspecific variation in grey seal skull shape results from balancing selection or phenotypic plasticity allowing for a remarkably generalist foraging behaviour. Moreover, the large overlap in skull shape between populations implies that the separate subspecies status of Atlantic and Baltic Sea grey seals is questionable from a morphological point of view.</p></div>","PeriodicalId":49330,"journal":{"name":"Zoology","volume":"153 ","pages":"Article 126023"},"PeriodicalIF":2.0,"publicationDate":"2022-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0944200622000241/pdfft?md5=2f158f0c587a8633f5e77b2c169ff9e3&pid=1-s2.0-S0944200622000241-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"39990740","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Shape and ontogenetic changes in otolith of the ocellated icefish (Chionodraco rastrospinosus) from the Bransfield Strait, Antarctic","authors":"Xiaoying Wei ,&nbsp;Guoping Zhu","doi":"10.1016/j.zool.2022.126025","DOIUrl":"10.1016/j.zool.2022.126025","url":null,"abstract":"<div><p><span>Fish otolith<span> shapes record ecological information of fish and are an important tool in taxonomic, phylogenetic, and dietary studies. Shape and ontogenetic variations in the otoliths of ocellated icefish (</span></span><span><em>Chionodraco</em><em> rastrospinosus</em></span><span>) in the Bransfield Strait, northern Antarctic Peninsula, were analyzed. Ontogenetic changes in otolith morphology were evident. The size of the otoliths mainly grew along the antero-posterior axis. The rostrum and pararostrum developed more than the antirostrum and postrostrum. Otolith variation occurred mainly in the dorsal side compared to ventral side. A row of small holes in the central region of the medial side and an irregular protruded structure on both sides of them, were specific diagnostic characteristics of </span><em>C. rastrospinosus</em> otoliths compared to other species of <em>Chionodraco</em>. Based on hierarchical clustering analysis, four types of otolith shapes are clearly distinguished, corresponding to larval, juvenile, young, and adult stages of <em>C. rastrospinosus</em><span>. This work contributes to the understanding of the ecology of commercially important benthic fishes and provides key information for ecomorphology<span> study and fishery management of this species. We suggest the effect of ontogeny needs to be considered when otolith shape data are used to study population structure and life history of this species.</span></span></p></div>","PeriodicalId":49330,"journal":{"name":"Zoology","volume":"153 ","pages":"Article 126025"},"PeriodicalIF":2.0,"publicationDate":"2022-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"40463141","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Form and function of the mantle edge in Protobranchia (Mollusca: Bivalvia)","authors":"Carmen Salas ,&nbsp;Juan de Dios Bueno-Pérez ,&nbsp;Juan Félix López-Téllez ,&nbsp;Antonio G. Checa","doi":"10.1016/j.zool.2022.126027","DOIUrl":"10.1016/j.zool.2022.126027","url":null,"abstract":"<div><p>We analyzed, by optical and transmission electron microscopy, the morphology and function of the mantle edge, including the formation of the periostracum, of ten species of protobranchs. Five species from the order Nuculida, four species from the order Nuculanida and one species from the order Solemyida were studied. A second outer fold, which seems to function as a template for the internal marginal crenulations of the valves, is present in the crenulated species of <em>Nucula</em>. The minute non-crenulated <em>Ennucula aegeensis</em> shows the glandular basal cells displaced toward the periostracal groove, resembling a minute additional fold between the outer and middle folds. Intense secretion of glycocalyx, together with active uptake of particles, have been observed in the inner epithelium of the middle mantle fold and the whole epithelium of the inner mantle fold in all the studied species. Contrary to the rest of the bivalves, all the protobranchs analyzed have two basal cells involved in the formation of the external nanometric pellicle of the periostracum, a character that would support the monophyly of protobranchs. A three-layered pattern is the general rule for the periostracum in protobranchs, like for other bivalves. The presence of pouches of translucent layer inside the tanned dark layer under periostracal folds is characteristic of the species with a folded periostracum; its function is unclear but could give flexibility to the periostracum. The non-nacreous internal shell layer and the presence of translucent pouches under periostracal folds in <em>Sarepta speciosa</em> resemble those found in nuculanids. However, the free periostracum is rather similar to those of <em>N. hanleyi</em> and <em>E. aegeensis,</em> with a continuous vesicular layer. All the latter supports the inclusion of <em>Sarepta</em> in the order Nuculanida but could indicate either a basal lineage or that the translucent vesicular layer is an adaptive trait.</p></div>","PeriodicalId":49330,"journal":{"name":"Zoology","volume":"153 ","pages":"Article 126027"},"PeriodicalIF":2.0,"publicationDate":"2022-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0944200622000289/pdfft?md5=630c382aa8f49427ceb87d1436e00bc9&pid=1-s2.0-S0944200622000289-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"40504483","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}