Mia C Adcock, Kendall R Moles, Nicole L Garrison, Samantha A Donohoo, Nathan V Whelan
North America is a hotspot of freshwater mussel diversity. However, over the last century, many anthropogenic stressors have led to substantial declines in freshwater mussels of the families Unionidae and Margaritiferidae in North America. Conserving the remaining mussel fauna is a priority, as they play an integral role in freshwater ecosystems. The Little River in Arkansas is home to one of the last remaining populations of the federally endangered freshwater mussel, Arcidens wheeleri (Unionidae: Anodontini). Population dynamics information is lacking for A. wheeleri, and no population genetics study has been conducted on this species. A greater understanding of the genetic diversity within a population can serve as a benchmark for developing an effective management plan. We sampled A. wheeleri from three locations in the Little River. Genomic data were generated with a single-enzyme restriction-site-associated DNA sequencing approach to assess genetic diversity and structure of A. wheeleri in the Little River. Genetic structure analyses indicated one genetic population among the three locations, with limited, fine-scale subpopulation structure. Observed heterozygosity values were considerably lower than expected heterozygosity values, with Ho = 0.14 and He = 0.22, likely indicating a genetic bottleneck. Demographic analysis of the Little River population of A. wheeleri also suggests a historical bottleneck. Furthermore, a high inbreeding coefficient (FIS = 0.33) indicates A. wheeleri in the Little River is losing genetic diversity. Data generated indicate considerable risk of extirpation for A. wheeleri from the Little River and should serve as a baseline for future monitoring. Given its high risk of extinction, we recommend increased study of A. wheeleri across its range and on-the-ground conservation actions that include habitat protection and restoration, which are the only options until a successful host fish and protocols are identified for propagation.
北美洲是淡水贻贝多样性的热点地区。然而，在过去的一个世纪里，许多人为压力因素导致北美淡水贻贝科（Unionidae）和淡水贻贝属（Margaritiferidae）的数量大幅减少。由于淡水贻贝在淡水生态系统中发挥着不可或缺的作用，因此保护剩余的贻贝动物群是当务之急。阿肯色州的小河是联邦濒危淡水贻贝 Arcidens wheeleri（联盟科：Anodontini）仅存种群之一的家园。轮子贻贝缺乏种群动态信息，也没有进行过种群遗传学研究。进一步了解种群内的遗传多样性可作为制定有效管理计划的基准。我们在小河的三个地点采集了车轮鱼样本。我们采用单酶限制性位点相关 DNA 测序方法生成了基因组数据，以评估小河中轮虫的遗传多样性和结构。遗传结构分析表明，三个地点有一个遗传种群，其亚种群结构有限且规模较小。观察到的杂合度值大大低于预期的杂合度值，Ho = 0.14，He = 0.22，这可能表明存在遗传瓶颈。对小河A. wheeleri种群的人口分析也表明存在历史瓶颈。此外，较高的近亲繁殖系数（FIS = 0.33）表明小河中的 A. wheeleri 正在丧失遗传多样性。所生成的数据表明，小河中的 A. wheeleri 有相当大的灭绝风险，应作为未来监测的基线。鉴于其灭绝的高风险，我们建议在其分布范围内加强对轮虫的研究，并采取包括栖息地保护和恢复在内的实地保护行动，这是在找到成功的宿主鱼类和繁殖协议之前的唯一选择。
{"title":"Population genomics of the endangered freshwater mussel, Arcidens wheeleri (Unionoidea: Unionidae: Anodontini), in the Little River, Arkansas, USA","authors":"Mia C Adcock, Kendall R Moles, Nicole L Garrison, Samantha A Donohoo, Nathan V Whelan","doi":"10.1093/mollus/eyae029","DOIUrl":"https://doi.org/10.1093/mollus/eyae029","url":null,"abstract":"North America is a hotspot of freshwater mussel diversity. However, over the last century, many anthropogenic stressors have led to substantial declines in freshwater mussels of the families Unionidae and Margaritiferidae in North America. Conserving the remaining mussel fauna is a priority, as they play an integral role in freshwater ecosystems. The Little River in Arkansas is home to one of the last remaining populations of the federally endangered freshwater mussel, Arcidens wheeleri (Unionidae: Anodontini). Population dynamics information is lacking for A. wheeleri, and no population genetics study has been conducted on this species. A greater understanding of the genetic diversity within a population can serve as a benchmark for developing an effective management plan. We sampled A. wheeleri from three locations in the Little River. Genomic data were generated with a single-enzyme restriction-site-associated DNA sequencing approach to assess genetic diversity and structure of A. wheeleri in the Little River. Genetic structure analyses indicated one genetic population among the three locations, with limited, fine-scale subpopulation structure. Observed heterozygosity values were considerably lower than expected heterozygosity values, with Ho = 0.14 and He = 0.22, likely indicating a genetic bottleneck. Demographic analysis of the Little River population of A. wheeleri also suggests a historical bottleneck. Furthermore, a high inbreeding coefficient (FIS = 0.33) indicates A. wheeleri in the Little River is losing genetic diversity. Data generated indicate considerable risk of extirpation for A. wheeleri from the Little River and should serve as a baseline for future monitoring. Given its high risk of extinction, we recommend increased study of A. wheeleri across its range and on-the-ground conservation actions that include habitat protection and restoration, which are the only options until a successful host fish and protocols are identified for propagation.","PeriodicalId":50126,"journal":{"name":"Journal of Molluscan Studies","volume":null,"pages":null},"PeriodicalIF":1.2,"publicationDate":"2024-08-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142195006","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Giacomo Chiappa, Giulia Fassio, Carlo Smriglio, Paolo Mariottini, Paolo G Albano, Maria Vittoria Modica, Dario Zuccon, Nicolas Puillandre, Marco Oliverio
Calliostoma Swainson, 1840, as currently conceived, is the most species-rich genus of the order Trochida, with over 350 recognized species worldwide. The shell variability in these vetigastropods is extremely high, resulting in conflicting taxonomic attributions at both the genus and species levels. In the Mediterranean Sea, the remarkable morphological diversity of the Calliostoma top shells has led to the description of dozens of different taxa, of which nine are currently accepted. This taxonomic framework was tested using an iterative taxonomic approach. Species delimitation (using assemble species by automatic partitioning, clade monophyly and Kimura-2-parameter distances) and phylogenetic analyses (maximum likelihood and Bayesian inference) were carried out on 247 specimens from the Mediterranean and neighbouring Atlantic, including eight Mediterranean species and the Azorean C. lividum, spanning a large part of the morphological diversity and geographic distribution of the genus in the area. The molecular dataset comprised one nuclear marker, internal transcribed spacer 2 (ITS 2), and two mitochondrial markers (cytochrome c oxidase subunit 1 and 16S ribosomal RNA). Results indicate that the number of species is overestimated, as only C. conulus, C. granulatum, C. zizyphinum and C. laugieri are supported by molecular data among the assessed species. It is suggested that the morphological characters commonly used to diagnose species are variable within a single taxon, as three nominal taxa, allegedly endemic to the Mediterranean Sea, are here shown to be a single genetic species (C. laugieri). An ITS 2 2D folding structure is also reported as potentially distinctive for calliostomatids, compared to known Vetigastropoda. Our study indicates that to address the taxonomy of calliostomatid top shells, an integrative approach including molecular data is highly advisable to support species delimitation and especially new species description.
目前认为，Calliostoma Swainson, 1840 是蛙形目中物种最丰富的属，在全世界有 350 多个公认的物种。这些软体动物的外壳变异性极高，导致在属和种的分类归属上相互矛盾。在地中海，Calliostoma 顶壳具有显著的形态多样性，因此被描述为数十个不同的类群，其中 9 个类群目前已被接受。该分类框架采用迭代分类法进行测试。对来自地中海和邻近大西洋的 247 个标本进行了物种划分（通过自动分区、支系单系化和木村-2 参数距离来组合物种）和系统发生分析（最大似然法和贝叶斯推断法），其中包括 8 个地中海物种和亚速尔群岛的 C. lividum，涵盖了该属在该地区的大部分形态多样性和地理分布。分子数据集包括一个核标记（内部转录间隔 2 (ITS 2)）和两个线粒体标记（细胞色素 c 氧化酶亚单位 1 和 16S 核糖体 RNA）。结果表明，物种数量被高估了，因为在评估的物种中，只有 C. conulus、C. granulatum、C. zizyphinum 和 C. laugieri 得到了分子数据的支持。这表明，通常用于诊断物种的形态特征在单个类群内是可变的，因为三个据称是地中海特有的标称类群在这里被证明是单个遗传物种（C. laugieri）。据报道，与已知的腹足纲动物相比，胼胝体动物的 ITS 2 2D 折叠结构可能具有独特性。我们的研究表明，要解决胼胝体顶贝类的分类问题，最好采用包括分子数据在内的综合方法来支持物种划分，尤其是新物种的描述。
{"title":"The polymorphic top-shell puzzle: iterative taxonomy of Calliostoma Swainson, 1840 (Gastropoda: Calliostomatidae), in the Mediterranean Sea","authors":"Giacomo Chiappa, Giulia Fassio, Carlo Smriglio, Paolo Mariottini, Paolo G Albano, Maria Vittoria Modica, Dario Zuccon, Nicolas Puillandre, Marco Oliverio","doi":"10.1093/mollus/eyae026","DOIUrl":"https://doi.org/10.1093/mollus/eyae026","url":null,"abstract":"Calliostoma Swainson, 1840, as currently conceived, is the most species-rich genus of the order Trochida, with over 350 recognized species worldwide. The shell variability in these vetigastropods is extremely high, resulting in conflicting taxonomic attributions at both the genus and species levels. In the Mediterranean Sea, the remarkable morphological diversity of the Calliostoma top shells has led to the description of dozens of different taxa, of which nine are currently accepted. This taxonomic framework was tested using an iterative taxonomic approach. Species delimitation (using assemble species by automatic partitioning, clade monophyly and Kimura-2-parameter distances) and phylogenetic analyses (maximum likelihood and Bayesian inference) were carried out on 247 specimens from the Mediterranean and neighbouring Atlantic, including eight Mediterranean species and the Azorean C. lividum, spanning a large part of the morphological diversity and geographic distribution of the genus in the area. The molecular dataset comprised one nuclear marker, internal transcribed spacer 2 (ITS 2), and two mitochondrial markers (cytochrome c oxidase subunit 1 and 16S ribosomal RNA). Results indicate that the number of species is overestimated, as only C. conulus, C. granulatum, C. zizyphinum and C. laugieri are supported by molecular data among the assessed species. It is suggested that the morphological characters commonly used to diagnose species are variable within a single taxon, as three nominal taxa, allegedly endemic to the Mediterranean Sea, are here shown to be a single genetic species (C. laugieri). An ITS 2 2D folding structure is also reported as potentially distinctive for calliostomatids, compared to known Vetigastropoda. Our study indicates that to address the taxonomy of calliostomatid top shells, an integrative approach including molecular data is highly advisable to support species delimitation and especially new species description.","PeriodicalId":50126,"journal":{"name":"Journal of Molluscan Studies","volume":null,"pages":null},"PeriodicalIF":1.2,"publicationDate":"2024-08-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141946845","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Jess A T Morgan, Malcolm C Dunning, Jennifer R Ovenden, Damien Broderick, Raewyn Street, Julia Davies, Karina C Hall
This study provides a comprehensive molecular phylogenetic analysis of Uroteuthis squid from the Indo-Pacific region. The main aim was to increase sample coverage from northern and eastern Australian waters to resolve the identity and distribution of Uroteuthis species taken by local fisheries. Two mitochondrial regions, cytochrome c oxidase subunit I (COI) and 16S ribosomal RNA (16S rRNA), were sequenced from 220 new specimens and analysed with a further 51 sequences from GenBank to create a combined phylogeny for the genus. Three nuclear regions, 18S ribosomal DNA (18S rDNA), 28S ribosomal DNA (28S rDNA) and rhodopsin, were also sequenced from representatives of each species. Based on the mitochondrial phylogeny plus distance and tree-based delimitation models, a COI species barcode gap of 4–5% is proposed for discriminating Uroteuthis species. Applying this gap partitioned many described species into species complexes; for example, U. duvaucelii, U. noctiluca and U. edulis resolved into 10 species. Although more conserved, mitochondrial 16S rRNA sequences differentiated all new species clades, whereas none of the nuclear markers resolved the closest species. Results confirm that neither U. chinensis nor U. edulis occurs in Australian waters. Five undescribed species are identified from northern and eastern Australia, of which four are consistent with earlier allozyme studies (and two align with existing DNA sequences). One is a new southeastern, deeper shelf species differentiated in this study, along with a sixth undescribed species from Indonesian waters. Results of the molecular analysis are now being used to inform complementary morphometric analyses for new species descriptions, and genetic stock structure assessments of these important fisheries resources.
这项研究对印度洋-太平洋地区的乌贼进行了全面的分子系统学分析。主要目的是扩大澳大利亚北部和东部水域的样本覆盖范围，以确定当地渔业捕捞的乌贼物种的身份和分布。对 220 个新标本的两个线粒体区域，即细胞色素 c 氧化酶亚单位 I（COI）和 16S 核糖体 RNA（16S rRNA）进行了测序，并与 GenBank 中的另外 51 个序列进行了分析，从而建立了该属的综合系统发生。此外，还对每个物种的三个核区，即 18S 核糖体 DNA（18S rDNA）、28S 核糖体 DNA（28S rDNA）和菱形蛋白进行了测序。根据线粒体系统发育加上距离和基于树的划分模型，提出了用于区分 Uroteuthis 物种的 COI 物种条形码差距为 4-5%。例如，U. duvaucelii、U. noctiluca 和 U. edulis 可分为 10 个物种。尽管线粒体 16S rRNA 序列的保守性更强，但它还是将所有新物种支系区分开来，而没有一个核标记能区分出最接近的物种。结果证实，U. chinensis 和 U. edulis 都不存在于澳大利亚水域。在澳大利亚北部和东部发现了五个未被描述的物种，其中四个与早期的同工酶研究结果一致（两个与现有的 DNA 序列一致）。其中一个是本研究中分化出的东南部深海大陆架新物种，还有一个是来自印度尼西亚水域的第六个未被描述的物种。分子分析的结果目前正被用于新物种描述的补充形态分析，以及这些重要渔业资源的遗传种群结构评估。
{"title":"Molecular delimitation of cryptic Australian squid species of the genus Uroteuthis Rehder, 1945 (Cephalopoda: Loliginidae), provides a baseline of diversity to resolve classification challenges throughout the Indo-Pacific","authors":"Jess A T Morgan, Malcolm C Dunning, Jennifer R Ovenden, Damien Broderick, Raewyn Street, Julia Davies, Karina C Hall","doi":"10.1093/mollus/eyae028","DOIUrl":"https://doi.org/10.1093/mollus/eyae028","url":null,"abstract":"This study provides a comprehensive molecular phylogenetic analysis of Uroteuthis squid from the Indo-Pacific region. The main aim was to increase sample coverage from northern and eastern Australian waters to resolve the identity and distribution of Uroteuthis species taken by local fisheries. Two mitochondrial regions, cytochrome c oxidase subunit I (COI) and 16S ribosomal RNA (16S rRNA), were sequenced from 220 new specimens and analysed with a further 51 sequences from GenBank to create a combined phylogeny for the genus. Three nuclear regions, 18S ribosomal DNA (18S rDNA), 28S ribosomal DNA (28S rDNA) and rhodopsin, were also sequenced from representatives of each species. Based on the mitochondrial phylogeny plus distance and tree-based delimitation models, a COI species barcode gap of 4–5% is proposed for discriminating Uroteuthis species. Applying this gap partitioned many described species into species complexes; for example, U. duvaucelii, U. noctiluca and U. edulis resolved into 10 species. Although more conserved, mitochondrial 16S rRNA sequences differentiated all new species clades, whereas none of the nuclear markers resolved the closest species. Results confirm that neither U. chinensis nor U. edulis occurs in Australian waters. Five undescribed species are identified from northern and eastern Australia, of which four are consistent with earlier allozyme studies (and two align with existing DNA sequences). One is a new southeastern, deeper shelf species differentiated in this study, along with a sixth undescribed species from Indonesian waters. Results of the molecular analysis are now being used to inform complementary morphometric analyses for new species descriptions, and genetic stock structure assessments of these important fisheries resources.","PeriodicalId":50126,"journal":{"name":"Journal of Molluscan Studies","volume":null,"pages":null},"PeriodicalIF":1.2,"publicationDate":"2024-08-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141946844","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Putri Afin Nurhayati, Ayu Savitri Nurinsiyah, Tri Atmowidi, Windra Priawandiputra
We conducted research on land snail diversity on the highest volcanic mountain in Java, Mt Semeru. This research aimed to gain data on the land snail species diversity in the area as well as analyse environmental variables that affect the land snail assemblages along the altitudinal gradients. A total of 40 plots of 10 × 10 m2 were examined in the altitudinal gradient of 800–1,200, 1,201–1,600, 1,601–2,000 and 2,001–2,400 m asl using a timed search method. In total, 788 individuals of land snails were collected, belonging to 22 species from 14 families. Fifteen species were new records for the area. Five endemic species were recorded on Mt Semeru. A single introduced species, Bradybaena similaris was found abundantly on the mountain at an altitude of more than 2,000 m asl. Multiple linear regression analyses showed a unimodal response of species richness for altitude, temperature and precipitation sums on Mt Semeru. In addition to these environmental variables, species richness is influenced by land use type and soil pH. These findings suggest that species and ecosystem management at the altitude 2,001–2,400 m asl is necessary to conserve endemic land snail species, which were found most abundantly at this altitude.
{"title":"Land snail assemblages along altitudinal gradients on Mount Semeru, the highest montane forest in Java, Indonesia","authors":"Putri Afin Nurhayati, Ayu Savitri Nurinsiyah, Tri Atmowidi, Windra Priawandiputra","doi":"10.1093/mollus/eyae027","DOIUrl":"https://doi.org/10.1093/mollus/eyae027","url":null,"abstract":"We conducted research on land snail diversity on the highest volcanic mountain in Java, Mt Semeru. This research aimed to gain data on the land snail species diversity in the area as well as analyse environmental variables that affect the land snail assemblages along the altitudinal gradients. A total of 40 plots of 10 × 10 m2 were examined in the altitudinal gradient of 800–1,200, 1,201–1,600, 1,601–2,000 and 2,001–2,400 m asl using a timed search method. In total, 788 individuals of land snails were collected, belonging to 22 species from 14 families. Fifteen species were new records for the area. Five endemic species were recorded on Mt Semeru. A single introduced species, Bradybaena similaris was found abundantly on the mountain at an altitude of more than 2,000 m asl. Multiple linear regression analyses showed a unimodal response of species richness for altitude, temperature and precipitation sums on Mt Semeru. In addition to these environmental variables, species richness is influenced by land use type and soil pH. These findings suggest that species and ecosystem management at the altitude 2,001–2,400 m asl is necessary to conserve endemic land snail species, which were found most abundantly at this altitude.","PeriodicalId":50126,"journal":{"name":"Journal of Molluscan Studies","volume":null,"pages":null},"PeriodicalIF":1.2,"publicationDate":"2024-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141946848","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Alvaro Roura, Rafael Bañón, Alejandro de Carlos, Julio Valeiras, Esther Abad, Alberto Serrano, Angel Guerra
The Argonautoidea is a monophyletic superfamily of pelagic incirrate octopods primarily distinguished by an unusual means of copulation where a sexually modified arm, or hectocotylus, is detached and transferred from dwarf males to the female. Males of the seven-arm octopus Haliphron atlanticus are scarcely observed and little is known about their reproductive strategy. A detailed description of H. atlanticus digestive system, hectocotylus morphology, histology and functioning was carried out with fresh and preserved material from two males captured in the Bay of Biscay (North Atlantic). It is the first time that a hydrostatic sac/swimbladder in the anterior region of the intestine is described in an argonautoid male. Investing in reproductive rather than somatic growth is evident in the dwarf males of H. atlanticus, which lack the Needham sac and the terminal organ. Functionally, these organs have been replaced by two external modifications at the distal end of the detachable hectocotylus: a spermatophore reservoir with a single long spermatophore and a muscular penis, both essential to ensure fertilization once the hectocotylus is detached from the dwarf males. Haliphron has been considered a monospecific genus, with a single species distributed around the world. However, mitochondrial genetic analysis (cytochrome c oxidase subunit I and 16S ribosomal RNA) supports the existence of at least two species of Haliphron, one in the northern Atlantic and another in the southern Atlantic/Pacific. Further genetic and morphological studies are needed to unravel the diversity of this oceanic octopod family.
八爪章鱼科（Argonautoidea）是中上层无脊八爪章鱼的一个单系超科，其主要特征是一种不寻常的交配方式，即从矮小的雄性章鱼身上分离出一条经过性改造的手臂（或称八爪），并将其转移到雌性章鱼身上。人们很少观察到七臂章鱼 Haliphron atlanticus 的雄性，对其繁殖策略也知之甚少。研究人员利用在比斯开湾（北大西洋）捕获的两只雄性七臂章鱼的新鲜和保存材料，详细描述了七臂章鱼的消化系统、八爪章鱼的形态、组织学和功能。这是首次描述箭鱼雄性肠道前部区域的静水囊/鳔。在缺乏尼德姆囊（Needham sac）和末端器官的侏儒雄性大西洋海牛中，生殖生长而非躯体生长的投入是显而易见的。从功能上看，这些器官被可分离的外胚轴远端上的两个外部改造所取代：一个带有单个长精子的精子贮藏器和一个肌肉阴茎，这两个器官对于确保一旦外胚轴从侏儒雄体上分离后的受精至关重要。Haliphron 一直被认为是一个单一种属，只有一个物种分布在世界各地。然而，线粒体遗传分析（细胞色素 c 氧化酶亚单位 I 和 16S 核糖体 RNA）支持至少存在两个 Haliphron 种，一个在大西洋北部，另一个在大西洋/太平洋南部。还需要进一步的遗传学和形态学研究来揭示这一大洋章足科动物的多样性。
{"title":"Dwarf males of the seven-arm octopus, Haliphron atlanticus: morphology and adaptations","authors":"Alvaro Roura, Rafael Bañón, Alejandro de Carlos, Julio Valeiras, Esther Abad, Alberto Serrano, Angel Guerra","doi":"10.1093/mollus/eyae025","DOIUrl":"https://doi.org/10.1093/mollus/eyae025","url":null,"abstract":"The Argonautoidea is a monophyletic superfamily of pelagic incirrate octopods primarily distinguished by an unusual means of copulation where a sexually modified arm, or hectocotylus, is detached and transferred from dwarf males to the female. Males of the seven-arm octopus Haliphron atlanticus are scarcely observed and little is known about their reproductive strategy. A detailed description of H. atlanticus digestive system, hectocotylus morphology, histology and functioning was carried out with fresh and preserved material from two males captured in the Bay of Biscay (North Atlantic). It is the first time that a hydrostatic sac/swimbladder in the anterior region of the intestine is described in an argonautoid male. Investing in reproductive rather than somatic growth is evident in the dwarf males of H. atlanticus, which lack the Needham sac and the terminal organ. Functionally, these organs have been replaced by two external modifications at the distal end of the detachable hectocotylus: a spermatophore reservoir with a single long spermatophore and a muscular penis, both essential to ensure fertilization once the hectocotylus is detached from the dwarf males. Haliphron has been considered a monospecific genus, with a single species distributed around the world. However, mitochondrial genetic analysis (cytochrome c oxidase subunit I and 16S ribosomal RNA) supports the existence of at least two species of Haliphron, one in the northern Atlantic and another in the southern Atlantic/Pacific. Further genetic and morphological studies are needed to unravel the diversity of this oceanic octopod family.","PeriodicalId":50126,"journal":{"name":"Journal of Molluscan Studies","volume":null,"pages":null},"PeriodicalIF":1.2,"publicationDate":"2024-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141882574","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Freshwater mussels have a substantial role in aquatic ecosystem function and provide valuable ecosystem services, including water filtration, nutrient cycling, habitat creation and sediment stabilization. While they face population declines globally that can negatively affect an ecosystem's health, such as reducing the water quality and increasing the turbidity, lack of information about the basic reproductive biology for most species makes their conservation much more difficult. Here, we monitored a population of Unio tumidus for a year to study its reproductive biology, gonad-dwelling parasites and growth rate in Lake Viinijärvi, Finland. Our data revealed that this species was dioecious with no evidence of hermaphroditism and was non-significantly female-biased (a male to female ratio of 1:1.3). Both sexes of U. tumidus had continuous gametogenesis during the study period with two peaks in the gonadosomatic index (GSI%) during November and May, followed by two clear declines in December and June. Gravidity period (brooding) of embryos or glochidia in the female's outer gills lasted from June to July. Therefore, this population of U. tumidus can be classified as a short-term breeder (tachytictic). The clear decline of GSI% in December might be a strategy that individuals of U. tumidus use to resorb resources back from the gonad for somatic maintenance during winter. Mean length of glochidia was 391 ± 0.049 µm, being among the largest known glochidia for Unionidae. No gonad-dwelling trematode parasites were detected and the population exhibited high fecundity (numbers of oocytes per female), with an average oocyte production of 242,000 ± 18,000. The studied population had a moderate growth rate with a maximum predicted age of 13 years and asymptotic length (the length at which growth slows down while the mussel continues to age, L∞) of 114 mm. Our study provides the first quantitative data and histological analysis of the reproductive biology of U. tumidus, serving as a basis for future research and conservation.
{"title":"Reproductive cycle, fecundity and growth of the freshwater mussel Unio tumidus (Bivalvia: Unionidae) from Lake Viinijärvi, Finland","authors":"Olfat Abdelsaleheen, Jouni Taskinen, Raine Kortet","doi":"10.1093/mollus/eyae024","DOIUrl":"https://doi.org/10.1093/mollus/eyae024","url":null,"abstract":"Freshwater mussels have a substantial role in aquatic ecosystem function and provide valuable ecosystem services, including water filtration, nutrient cycling, habitat creation and sediment stabilization. While they face population declines globally that can negatively affect an ecosystem's health, such as reducing the water quality and increasing the turbidity, lack of information about the basic reproductive biology for most species makes their conservation much more difficult. Here, we monitored a population of Unio tumidus for a year to study its reproductive biology, gonad-dwelling parasites and growth rate in Lake Viinijärvi, Finland. Our data revealed that this species was dioecious with no evidence of hermaphroditism and was non-significantly female-biased (a male to female ratio of 1:1.3). Both sexes of U. tumidus had continuous gametogenesis during the study period with two peaks in the gonadosomatic index (GSI%) during November and May, followed by two clear declines in December and June. Gravidity period (brooding) of embryos or glochidia in the female's outer gills lasted from June to July. Therefore, this population of U. tumidus can be classified as a short-term breeder (tachytictic). The clear decline of GSI% in December might be a strategy that individuals of U. tumidus use to resorb resources back from the gonad for somatic maintenance during winter. Mean length of glochidia was 391 ± 0.049 µm, being among the largest known glochidia for Unionidae. No gonad-dwelling trematode parasites were detected and the population exhibited high fecundity (numbers of oocytes per female), with an average oocyte production of 242,000 ± 18,000. The studied population had a moderate growth rate with a maximum predicted age of 13 years and asymptotic length (the length at which growth slows down while the mussel continues to age, L∞) of 114 mm. Our study provides the first quantitative data and histological analysis of the reproductive biology of U. tumidus, serving as a basis for future research and conservation.","PeriodicalId":50126,"journal":{"name":"Journal of Molluscan Studies","volume":null,"pages":null},"PeriodicalIF":1.2,"publicationDate":"2024-07-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141587223","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The spermatozoa of 14 species (four genera) of Lottiidae and one species of Acmaeidae are described by transmission electron microscopy. All have ect-aquasperm, which are relatively small, morphologically simple, free-swimming sperm produced by species with external fertilization. Based on the size, shape and structure of the nucleus and acrosome, as well as features of the mid-piece, several morphological sperm ‘types’ are recognized within the species of Lottioidea described by the present and several previous studies. Sperm morphology largely supports current taxonomy as well as systematic and phylogenetic relationships. However, the morphology of the sperm of Lottia dorsuosa suggests that its generic status should be re-examined. The sperm morphology of Niveotectura pallida (formerly Acmaea pallida) is more similar to that of species of Tectura than of Acmaea mitra, supporting the current placement of N. pallida in the Lottiidae. This result is at odds with the close relationship between N. pallida and A. mitra indicated by recent phylogenies based on molecular data.
{"title":"Comparative sperm morphology of 15 species of limpet (Mollusca: Patellogastropoda: Lottioidea) and correlation with current systematics and phylogenies","authors":"Alan N Hodgson, John Buckland-Nicks","doi":"10.1093/mollus/eyae023","DOIUrl":"https://doi.org/10.1093/mollus/eyae023","url":null,"abstract":"The spermatozoa of 14 species (four genera) of Lottiidae and one species of Acmaeidae are described by transmission electron microscopy. All have ect-aquasperm, which are relatively small, morphologically simple, free-swimming sperm produced by species with external fertilization. Based on the size, shape and structure of the nucleus and acrosome, as well as features of the mid-piece, several morphological sperm ‘types’ are recognized within the species of Lottioidea described by the present and several previous studies. Sperm morphology largely supports current taxonomy as well as systematic and phylogenetic relationships. However, the morphology of the sperm of Lottia dorsuosa suggests that its generic status should be re-examined. The sperm morphology of Niveotectura pallida (formerly Acmaea pallida) is more similar to that of species of Tectura than of Acmaea mitra, supporting the current placement of N. pallida in the Lottiidae. This result is at odds with the close relationship between N. pallida and A. mitra indicated by recent phylogenies based on molecular data.","PeriodicalId":50126,"journal":{"name":"Journal of Molluscan Studies","volume":null,"pages":null},"PeriodicalIF":1.2,"publicationDate":"2024-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141550915","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Yi Yang, José Templado, Nicolas Puillandre, Rafael Zardoya
Mud snails (family Nassariidae) represent a highly diversified lineage within the superfamily Buccinoidea. Recent molecular phylogenies contradicted in some instances the traditional nassariid classification and revealed important levels of homoplasy in phenotypic characters. In order to clarify the boundaries of the family Nassariidae, as well as to inquire on the diversification of the cosmopolitan Nassariinae, a robust phylogenetic framework is needed. Here, the near-complete mitogenomes of 31 species representing almost all lineages of Nassariidae plus several buccinoid outgroups were sequenced. All mitogenomes of buccinoids shared the same gene order, which is identical to the consensus reported for caenogastropods. The monophyly of Nassariidae as previously defined was not confirmed. The reconstructed phylogeny revealed distant relationships between the genera Cyllene, Anentome, Tomlinia, Engoniophos, Phos and Antillophos and the majority of nassariids, represented by Nassariinae + Bullia. Within Nassariinae, a robust phylogeny, which recognized a total of seven regional groups, was reconstructed. The West Atlantic/Mediterranean genus Tritia was divided into three clades. The biogeographical analysis together with the inferred chronogram suggested that Nassariinae might have originated during the late Paleocene in the Indo-Pacific region. Subsequent climate change and continental drift events triggered diversification within the subfamily, leading to the worldwide distribution of current genera.
{"title":"Mitogenomic phylogeny of Nassariidae (Neogastropoda: Buccinoidea)","authors":"Yi Yang, José Templado, Nicolas Puillandre, Rafael Zardoya","doi":"10.1093/mollus/eyae020","DOIUrl":"https://doi.org/10.1093/mollus/eyae020","url":null,"abstract":"Mud snails (family Nassariidae) represent a highly diversified lineage within the superfamily Buccinoidea. Recent molecular phylogenies contradicted in some instances the traditional nassariid classification and revealed important levels of homoplasy in phenotypic characters. In order to clarify the boundaries of the family Nassariidae, as well as to inquire on the diversification of the cosmopolitan Nassariinae, a robust phylogenetic framework is needed. Here, the near-complete mitogenomes of 31 species representing almost all lineages of Nassariidae plus several buccinoid outgroups were sequenced. All mitogenomes of buccinoids shared the same gene order, which is identical to the consensus reported for caenogastropods. The monophyly of Nassariidae as previously defined was not confirmed. The reconstructed phylogeny revealed distant relationships between the genera Cyllene, Anentome, Tomlinia, Engoniophos, Phos and Antillophos and the majority of nassariids, represented by Nassariinae + Bullia. Within Nassariinae, a robust phylogeny, which recognized a total of seven regional groups, was reconstructed. The West Atlantic/Mediterranean genus Tritia was divided into three clades. The biogeographical analysis together with the inferred chronogram suggested that Nassariinae might have originated during the late Paleocene in the Indo-Pacific region. Subsequent climate change and continental drift events triggered diversification within the subfamily, leading to the worldwide distribution of current genera.","PeriodicalId":50126,"journal":{"name":"Journal of Molluscan Studies","volume":null,"pages":null},"PeriodicalIF":1.2,"publicationDate":"2024-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141550892","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The Astartidae (Bivalvia) are a common benthic fossil in the British Lower Jurassic and as such it is important to understand their taxonomy so as to use them as a study system with which to consider environmental change through, and extinction events in, this epoch. The majority of the species of the Astartidae from the British Lower Jurassic are taxa within the subfamily Astartinae, encompassing the genera Neocrassina, Coelastarte and Oxyeurax. There has been some question as to whether those shells attributed to Neocrassina could be further split, with two species assigned to this genus having some characters that are atypical. We prefer to retain the atypical species within ?Neocrassina, the genus with which they have the greatest affinity, rather than erect another genus. This study assigns the suite of British Lower Jurassic fossil bivalves attributed to Nicaniella to Oxyeurax, based on the presence of a poorly defined 3a tooth and form of commarginal ridge ornament. Differentiation at the species level in Astartinae is complicated; the subfamily exhibits generally low disparity compared with other bivalves, compounded by ecomorphological effects and, in some cases, sexual dimorphism. We show that the Neocrassina lineage exhibits gradual changes in shape, as well as hinge plate development and complexity, through the Lower Jurassic, and identify potential sexual dimorphism in species of Oxyeurax. The temporally overlapping species of Oxyeurax display varying degrees of ornamental development which may well be environmentally controlled and are used in this study to define distinct new species. This study recognizes 12 distinct species of Astartinae from the British Lower Jurassic. Nine are established taxa (Neocrassina elegans, N. expansa, N. gueuxii, N. lurida, N. phaedra, ?N. camertonensis, ?N. dentilabrum, Oxyeurax duplicata, O. striatosulcata), whilstthree are new species (Coelastarte wardenensis, O. mickletonensis and Oxyeurax thompsoni). Only two of the British Lower Jurassic Astartinae species appear to have survived the global Early Toarcian extinction event as represented in British successions; one Neocrassina and one Oxyeurax. However, the lack of fossiliferous, high energy near shore environments in the early Toarcian may bias this observation, especially for Oxyeurax.
{"title":"Revision of the British Lower Jurassic Astartinae (Bivalvia)","authors":"Robin I Knight, Katie S Collins, Noel J Morris","doi":"10.1093/mollus/eyae010","DOIUrl":"https://doi.org/10.1093/mollus/eyae010","url":null,"abstract":"The Astartidae (Bivalvia) are a common benthic fossil in the British Lower Jurassic and as such it is important to understand their taxonomy so as to use them as a study system with which to consider environmental change through, and extinction events in, this epoch. The majority of the species of the Astartidae from the British Lower Jurassic are taxa within the subfamily Astartinae, encompassing the genera Neocrassina, Coelastarte and Oxyeurax. There has been some question as to whether those shells attributed to Neocrassina could be further split, with two species assigned to this genus having some characters that are atypical. We prefer to retain the atypical species within ?Neocrassina, the genus with which they have the greatest affinity, rather than erect another genus. This study assigns the suite of British Lower Jurassic fossil bivalves attributed to Nicaniella to Oxyeurax, based on the presence of a poorly defined 3a tooth and form of commarginal ridge ornament. Differentiation at the species level in Astartinae is complicated; the subfamily exhibits generally low disparity compared with other bivalves, compounded by ecomorphological effects and, in some cases, sexual dimorphism. We show that the Neocrassina lineage exhibits gradual changes in shape, as well as hinge plate development and complexity, through the Lower Jurassic, and identify potential sexual dimorphism in species of Oxyeurax. The temporally overlapping species of Oxyeurax display varying degrees of ornamental development which may well be environmentally controlled and are used in this study to define distinct new species. This study recognizes 12 distinct species of Astartinae from the British Lower Jurassic. Nine are established taxa (Neocrassina elegans, N. expansa, N. gueuxii, N. lurida, N. phaedra, ?N. camertonensis, ?N. dentilabrum, Oxyeurax duplicata, O. striatosulcata), whilstthree are new species (Coelastarte wardenensis, O. mickletonensis and Oxyeurax thompsoni). Only two of the British Lower Jurassic Astartinae species appear to have survived the global Early Toarcian extinction event as represented in British successions; one Neocrassina and one Oxyeurax. However, the lack of fossiliferous, high energy near shore environments in the early Toarcian may bias this observation, especially for Oxyeurax.","PeriodicalId":50126,"journal":{"name":"Journal of Molluscan Studies","volume":null,"pages":null},"PeriodicalIF":1.2,"publicationDate":"2024-06-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141502443","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Increasing coastal development and global warming have resulted in large-scale habitat changes, with artificial coastal structures replacing extensive tracts of natural shores. In Singapore, for example, more than 63% of the natural coastline has been replaced by seawalls. Multiple studies from both temperate and tropical regions have compared species diversity supported by these artificial structures with natural rocky shores. Few, however, have estimated and compared the population size and movement of common intertidal species between these two habitat types. Using mark–recapture techniques, this study investigated: (1) the population size of three common gastropod genera (Nerita spp., Trochus spp. and Turbo spp.) and (2) differences in displacement of Nerita spp. and Trochus spp., two common species found on natural rocky shores and seawalls in Singapore. The results of our mark–recapture surveys indicated that seawalls supported large densities of Nerita spp.—more than 50 times greater than that on adjacent rocky shores. The mark–recapture data also revealed that movement of the gastropod species differed between the two habitats, with individuals on seawalls generally travelling longer distances.
{"title":"Population size and movement ecology of intertidal gastropods on rocky shores and seawalls in Singapore","authors":"Hannah H J Yeo, Lynette H L Loke, Peter A Todd","doi":"10.1093/mollus/eyae016","DOIUrl":"https://doi.org/10.1093/mollus/eyae016","url":null,"abstract":"Increasing coastal development and global warming have resulted in large-scale habitat changes, with artificial coastal structures replacing extensive tracts of natural shores. In Singapore, for example, more than 63% of the natural coastline has been replaced by seawalls. Multiple studies from both temperate and tropical regions have compared species diversity supported by these artificial structures with natural rocky shores. Few, however, have estimated and compared the population size and movement of common intertidal species between these two habitat types. Using mark–recapture techniques, this study investigated: (1) the population size of three common gastropod genera (Nerita spp., Trochus spp. and Turbo spp.) and (2) differences in displacement of Nerita spp. and Trochus spp., two common species found on natural rocky shores and seawalls in Singapore. The results of our mark–recapture surveys indicated that seawalls supported large densities of Nerita spp.—more than 50 times greater than that on adjacent rocky shores. The mark–recapture data also revealed that movement of the gastropod species differed between the two habitats, with individuals on seawalls generally travelling longer distances.","PeriodicalId":50126,"journal":{"name":"Journal of Molluscan Studies","volume":null,"pages":null},"PeriodicalIF":1.2,"publicationDate":"2024-06-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141502444","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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