Pub Date : 2024-09-01DOI: 10.1016/j.asd.2024.101383
The rectum is an important part of the alimentary canal responsible for ion and water reabsorption of insects. However, it has rarely been studied in the larvae of Panorpidae, the largest family in Mecoptera. Here, we investigated the ultrastructure of larval rectum of the scorpionfly Panorpa liui Hua, 1997 using light and transmission electron microscopy. The rectum comprises tracheal muscular layers, connective tissue, non-cellular basal lamina, junctional cells, rectal epithelium, cuticle with irregular outlines, and a central lumen. The rectal epithelium is infolded to form six longitudinal rectal folds, which are distinct from rectal pads or papillae. In each rectal fold, the apical and basal plasma membranes of epithelial cells are infolded and the lateral plasma membranes form septate and scalariform junctions. The well-developed rectal folds are postulated to be closely associated with reabsorption of ions and water in the larvae. The associations of rectal folds with larval behaviors are briefly discussed in Mecoptera.
{"title":"Ultrastructure of the larval rectum of the scorpionfly Panorpa liui (Mecoptera: Panorpidae)","authors":"","doi":"10.1016/j.asd.2024.101383","DOIUrl":"10.1016/j.asd.2024.101383","url":null,"abstract":"<div><p>The rectum is an important part of the alimentary canal responsible for ion and water reabsorption of insects. However, it has rarely been studied in the larvae of Panorpidae, the largest family in Mecoptera. Here, we investigated the ultrastructure of larval rectum of the scorpionfly <em>Panorpa liui</em> Hua, 1997 using light and transmission electron microscopy. The rectum comprises tracheal muscular layers, connective tissue, non-cellular basal lamina, junctional cells, rectal epithelium, cuticle with irregular outlines, and a central lumen. The rectal epithelium is infolded to form six longitudinal rectal folds, which are distinct from rectal pads or papillae. In each rectal fold, the apical and basal plasma membranes of epithelial cells are infolded and the lateral plasma membranes form septate and scalariform junctions. The well-developed rectal folds are postulated to be closely associated with reabsorption of ions and water in the larvae. The associations of rectal folds with larval behaviors are briefly discussed in Mecoptera.</p></div>","PeriodicalId":55461,"journal":{"name":"Arthropod Structure & Development","volume":null,"pages":null},"PeriodicalIF":1.7,"publicationDate":"2024-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142146959","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-01DOI: 10.1016/j.asd.2024.101382
Solitary bees play a crucial role in ecological systems, contributing to the pollination of crops and wild plants. All females are reproductive, and their habitat requirements include nesting sites, food resources and nesting materials. Although these activities require the ability to detect biotic and abiotic stimuli in the environment, the sensory system of these species is poorly studied. In this study, the antennal sensilla of five solitary bee species belonging to three Apoidea families were investigated using scanning electron microscopy. These included two species of stem-nesting bees, Ceratina cucurbitina (Rossi, 1792) (Apidae) and Osmia scutellaris (Morawitz, 1868) (Megachilidae), and three species of ground-nesting bees, Lasioglossum brevicorne (Schenck, 1870), Lasioglossum leucozonium (Schrank, 1781), and Lasioglossum villosulum (Kirby, 1802) (Halictidae). Thirteen different types of antennal sensilla were identified in females based on their morphological characteristics: sensilla trichodea (subtypes STI, II, III), chaetica (subtypes SchI, II), basiconica (subtypes SBI, II, III, IV), placodea, campaniformia, coeloconica, and ampullacea. Their functional role was discussed and morphology was compared among the species and within the antennal segments in each species. The results provide a baseline for further physiological and behavioural studies to determine the role of antennal sensilla in habitat selection, food search and nesting site selection.
{"title":"Morphology and distribution of antennal sensilla in five species of solitary bees (Hymenoptera, Apoidea)","authors":"","doi":"10.1016/j.asd.2024.101382","DOIUrl":"10.1016/j.asd.2024.101382","url":null,"abstract":"<div><p>Solitary bees play a crucial role in ecological systems, contributing to the pollination of crops and wild plants. All females are reproductive, and their habitat requirements include nesting sites, food resources and nesting materials. Although these activities require the ability to detect biotic and abiotic stimuli in the environment, the sensory system of these species is poorly studied. In this study, the antennal sensilla of five solitary bee species belonging to three Apoidea families were investigated using scanning electron microscopy. These included two species of stem-nesting bees, <em>Ceratina cucurbitina</em> (Rossi, 1792) (Apidae) and <em>Osmia scutellaris</em> (Morawitz, 1868) (Megachilidae), and three species of ground-nesting bees, <em>Lasioglossum brevicorne</em> (Schenck, 1870), <em>Lasioglossum leucozonium</em> (Schrank, 1781), and <em>Lasioglossum villosulum</em> (Kirby, 1802) (Halictidae). Thirteen different types of antennal sensilla were identified in females based on their morphological characteristics: sensilla trichodea (subtypes STI, II, III), chaetica (subtypes SchI, II), basiconica (subtypes SBI, II, III, IV), placodea, campaniformia, coeloconica, and ampullacea. Their functional role was discussed and morphology was compared among the species and within the antennal segments in each species. The results provide a baseline for further physiological and behavioural studies to determine the role of antennal sensilla in habitat selection, food search and nesting site selection.</p></div>","PeriodicalId":55461,"journal":{"name":"Arthropod Structure & Development","volume":null,"pages":null},"PeriodicalIF":1.7,"publicationDate":"2024-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142146958","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-01DOI: 10.1016/j.asd.2024.101385
Across the species of spear-winged flies (Diptera: Lonchopteridae) there is a remarkable variation in size of the female reproductive tract, especially of the spermathecae. In this family there are two tubular spermathecae, which are divided into four morphologically and histologically distinct sections of different lengths and functions. The dimensions of the spermathecae and their individual sections were examined across 11 Lonchoptera species and related to the dimensions of the respective spermatozoa. 3D reconstructions from serial sectioning made it possible to include the volume in these considerations, which is a new approach in this context. Results show that the spermathecae are always longer than the respective spermatozoa. There is a highly significant positive linear correlation between the length of the spermatozoa and the length of the spermathecae in total as well as some of the individual spermathecal sections, suggesting a coevolution of these characters. Moreover, the volume of the spermathecae is much larger in those species with longer and more voluminous spermatozoa, but the volume increase is not sufficient to keep constant the number of spermatozoa that fit within. The observed patterns are discussed with respect to their functional and evolutionary implications, including a new hypothesis on the possible selective advantage of increased spermatozoon length.
{"title":"Coevolution of spermatozoa and spermathecae in Lonchopteridae (Diptera)","authors":"","doi":"10.1016/j.asd.2024.101385","DOIUrl":"10.1016/j.asd.2024.101385","url":null,"abstract":"<div><p>Across the species of spear-winged flies (Diptera: Lonchopteridae) there is a remarkable variation in size of the female reproductive tract, especially of the spermathecae. In this family there are two tubular spermathecae, which are divided into four morphologically and histologically distinct sections of different lengths and functions. The dimensions of the spermathecae and their individual sections were examined across 11 <em>Lonchoptera</em> species and related to the dimensions of the respective spermatozoa. 3D reconstructions from serial sectioning made it possible to include the volume in these considerations, which is a new approach in this context. Results show that the spermathecae are always longer than the respective spermatozoa. There is a highly significant positive linear correlation between the length of the spermatozoa and the length of the spermathecae in total as well as some of the individual spermathecal sections, suggesting a coevolution of these characters. Moreover, the volume of the spermathecae is much larger in those species with longer and more voluminous spermatozoa, but the volume increase is not sufficient to keep constant the number of spermatozoa that fit within. The observed patterns are discussed with respect to their functional and evolutionary implications, including a new hypothesis on the possible selective advantage of increased spermatozoon length.</p></div>","PeriodicalId":55461,"journal":{"name":"Arthropod Structure & Development","volume":null,"pages":null},"PeriodicalIF":1.7,"publicationDate":"2024-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S1467803924000550/pdfft?md5=e3e1b66572e0381459443308d38ece77&pid=1-s2.0-S1467803924000550-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142168934","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-01DOI: 10.1016/j.asd.2024.101384
A genomic investigation of the potentially invasive firefly Photinus signaticollis Blanchard1845 has been performed and led to the obtention of its complete 16,411 bp long mitochondrial genome. The mitogenome encodes 13 protein-coding genes, 22 tRNA genes and 2 rRNA genes. With other species of the Photinus complex it shares several premature terminations of some protein-coding genes and also an overlap between cox1 and tRNA-Tyr. By data-mining, the complete luciferase and luciferin-regenerating genes were also identified from the contigs file and compared with existing data, in addition to WG and CAD, two genes used in pioneering phylogenetic studies on fireflies. Three maximum likelihood phylogenies were derived from all these data. The multigene phylogeny based on all mitochondrial protein-coding genes strongly associates P. signaticollis with Photinus pyralis Linnaeus, 1758 and the lantern-less daily “winter firefly”, Photinus corruscus Linnaeus, 1767. A second phylogeny based on concatenated sequences of the cox1, WG and CAD genes positions P. signaticollis as a sister clade to a large cluster of species containing the 7 sub-groups previously evidenced among the North American species of the Photinus complex. A third phylogeny based on the amino-acid sequence of the luciferase protein associates P. signaticollis to Photinus scintillans. The analysis presented here will most certainly help to come to a better understanding of the very complex inter-relationships in the very large Photinus genus.
{"title":"Genomics investigation of the potentially invasive firefly Photinus signaticollis Blanchard 1845: Complete mitochondrial genome, multigene phylogenies and obtention of the luciferase and luciferin-regenerating genes","authors":"","doi":"10.1016/j.asd.2024.101384","DOIUrl":"10.1016/j.asd.2024.101384","url":null,"abstract":"<div><p>A genomic investigation of the potentially invasive firefly <em>Photinus signaticollis</em> Blanchard1845 has been performed and led to the obtention of its complete 16,411 bp long mitochondrial genome. The mitogenome encodes 13 protein-coding genes, 22 tRNA genes and 2 rRNA genes. With other species of the <em>Photinus</em> complex it shares several premature terminations of some protein-coding genes and also an overlap between <em>cox1</em> and <em>tRNA-Tyr</em>. By data-mining, the complete luciferase and luciferin-regenerating genes were also identified from the contigs file and compared with existing data, in addition to <em>WG</em> and CAD, two genes used in pioneering phylogenetic studies on fireflies. Three maximum likelihood phylogenies were derived from all these data. The multigene phylogeny based on all mitochondrial protein-coding genes strongly associates <em>P. signaticollis</em> with <em>Photinus pyralis</em> Linnaeus, 1758 and the lantern-less daily “winter firefly”, <em>Photinus corruscus</em> Linnaeus, 1767. A second phylogeny based on concatenated sequences of the <em>cox1</em>, <em>WG</em> and <em>CAD</em> genes positions <em>P. signaticollis</em> as a sister clade to a large cluster of species containing the 7 sub-groups previously evidenced among the North American species of the <em>Photinus</em> complex. A third phylogeny based on the amino-acid sequence of the luciferase protein associates <em>P. signaticollis</em> to <em>Photinus scintillans.</em> The analysis presented here will most certainly help to come to a better understanding of the very complex inter-relationships in the very large <em>Photinus</em> genus.</p></div>","PeriodicalId":55461,"journal":{"name":"Arthropod Structure & Development","volume":null,"pages":null},"PeriodicalIF":1.7,"publicationDate":"2024-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142241875","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-23DOI: 10.1016/j.asd.2024.101381
Sapygidae is a small family of Aculeata (Hymenoptera), which is divided into two subfamilies Fedtschenkiinae and Sapyginae. The morphology of the skeleton of the sting apparatus in some European species of Sapyginae, which are kleptoparasites of wild bees from the families Megachilidae, Apidae and Colletidae, was examined. Significant differences in its skeletal structure were noted between Sapygina decemguttata and representatives of the genera Sapyga and Monosapyga. The sting of Sapygina belongs to the decurved type, while Sapyga and Monosapyga have a sting close to the coiled type. A comparison of the structure of the skeletons of the sting apparatuses of Sapygina and Sapyga with that of Fedtschenkia (according to other authors) was made. The similarity of the structure of the sting apparatuses of Sapygina and Fedtschenkia was noted. The possibility of using the Sapyginae sting as an ovipositor is discussed.
{"title":"Morphology of the sting apparatus in sapygid wasps of the subfamily Sapyginae (Hymenoptera: Sapygidae)","authors":"","doi":"10.1016/j.asd.2024.101381","DOIUrl":"10.1016/j.asd.2024.101381","url":null,"abstract":"<div><p>Sapygidae is a small family of Aculeata (Hymenoptera), which is divided into two subfamilies Fedtschenkiinae and Sapyginae. The morphology of the skeleton of the sting apparatus in some European species of Sapyginae, which are kleptoparasites of wild bees from the families Megachilidae, Apidae and Colletidae, was examined. Significant differences in its skeletal structure were noted between <em>Sapygina decemguttata</em> and representatives of the genera <em>Sapyga</em> and <em>Monosapyga</em>. The sting of <em>Sapygina</em> belongs to the decurved type, while <em>Sapyga</em> and <em>Monosapyga</em> have a sting close to the coiled type. A comparison of the structure of the skeletons of the sting apparatuses of <em>Sapygina</em> and <em>Sapyga</em> with that of <em>Fedtschenkia</em> (according to other authors) was made. The similarity of the structure of the sting apparatuses of <em>Sapygina</em> and <em>Fedtschenkia</em> was noted. The possibility of using the Sapyginae sting as an ovipositor is discussed.</p></div>","PeriodicalId":55461,"journal":{"name":"Arthropod Structure & Development","volume":null,"pages":null},"PeriodicalIF":1.7,"publicationDate":"2024-08-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142047797","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-10DOI: 10.1016/j.asd.2024.101380
Perlidae stands as the most diverse family within Plecoptera, with evidence suggesting possible adaptation to warmer aquatic environments. Tracheal gills are hypothesized to have played a pivotal role in this radiation process. This study presents the description of a fossilized stonefly larva with gills, preserved as a fresh exuvia in mid-Cretaceous Kachin amber from northern Myanmar. The larva was classified within the family Perlidae based on distinctive morphological traits, including toothed lacinia and sharp-cusped mandibles, slender palps, glossae shorter than rounded paraglossae, and highly branched gills on the sides and ventral surface of thoracic segments. Additionally, the presence of a transverse, sparse, and irregular setal row on the occiput further indicates classification within the subfamily Acroneuriinae. Notably, the fossilized larva displays striking similarities in gill morphology and distribution to certain extant members within Perlidae, suggesting that these gill structures have an advantage in various aquatic habitats.
{"title":"The structure of a gilled stonefly larva from the mid-Cretaceous Kachin amber","authors":"","doi":"10.1016/j.asd.2024.101380","DOIUrl":"10.1016/j.asd.2024.101380","url":null,"abstract":"<div><p>Perlidae stands as the most diverse family within Plecoptera, with evidence suggesting possible adaptation to warmer aquatic environments. Tracheal gills are hypothesized to have played a pivotal role in this radiation process. This study presents the description of a fossilized stonefly larva with gills, preserved as a fresh exuvia in mid-Cretaceous Kachin amber from northern Myanmar. The larva was classified within the family Perlidae based on distinctive morphological traits, including toothed lacinia and sharp-cusped mandibles, slender palps, glossae shorter than rounded paraglossae, and highly branched gills on the sides and ventral surface of thoracic segments. Additionally, the presence of a transverse, sparse, and irregular setal row on the occiput further indicates classification within the subfamily Acroneuriinae. Notably, the fossilized larva displays striking similarities in gill morphology and distribution to certain extant members within Perlidae, suggesting that these gill structures have an advantage in various aquatic habitats.</p></div>","PeriodicalId":55461,"journal":{"name":"Arthropod Structure & Development","volume":null,"pages":null},"PeriodicalIF":1.7,"publicationDate":"2024-08-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141918148","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-01DOI: 10.1016/j.asd.2024.101372
This paper tests hypotheses of independent parallel evolution of the rostrosoma among euchelicerate taxa by analyzing the microscopic anatomy and histology of the rostrosoma of Uropygi (Schizomida and Thelyphonida) and comparing it with the morphology of the snout region in other euchelicerates. The study employs analysis of multiple histological serial sections, μCT-imaging, and graphical as well as computer-based 3D reconstruction. Results of the study are that Thelyphonida and Schizomida share the same morphology of the rostrosoma. The rostrosoma of both groups contains a unique arrangement of musculature that is functionally interpreted as pre-oral suction pump. This is followed by a pharyngeal suction pump. The muscles of the pharyngeal suction pump attach to the epistome and the epipharyngeal sclerite. Neither Schizomida nor Thelyphonida possess a postcerebral suction pump as reported earlier. The microscopic anatomy of the rostrosoma of both taxa is unique and does not compare with any of the other euchelicerates, thus supporting the idea of independent evolutionary origin of the rostrosoma. Thelyphonida, Amblypygi and Scorpiones share the occurrence of a large epipharyngeal/epistomal sclerite with associated musculature, which is a feature that lines up with the Arachnopulmonata concept. A comparison with all Euchelicerata taxa shows that the snout region is formed by homologous morphological elements but the specific arrangement, additions and reductions shape the formation of the rostrosoma, so that parallel evolution of homologous parts of the arachnid ground pattern can be assumed that has formed those elements into convergent morphologies.
{"title":"Comparative microscopic anatomy of Schizomida – 2. The rostrosoma and the pharyngeal suction pump","authors":"","doi":"10.1016/j.asd.2024.101372","DOIUrl":"10.1016/j.asd.2024.101372","url":null,"abstract":"<div><p>This paper tests hypotheses of independent parallel evolution of the rostrosoma among euchelicerate taxa by analyzing the microscopic anatomy and histology of the rostrosoma of Uropygi (Schizomida and Thelyphonida) and comparing it with the morphology of the snout region in other euchelicerates. The study employs analysis of multiple histological serial sections, μCT-imaging, and graphical as well as computer-based 3D reconstruction. Results of the study are that Thelyphonida and Schizomida share the same morphology of the rostrosoma. The rostrosoma of both groups contains a unique arrangement of musculature that is functionally interpreted as pre-oral suction pump. This is followed by a pharyngeal suction pump. The muscles of the pharyngeal suction pump attach to the epistome and the epipharyngeal sclerite. Neither Schizomida nor Thelyphonida possess a postcerebral suction pump as reported earlier. The microscopic anatomy of the rostrosoma of both taxa is unique and does not compare with any of the other euchelicerates, thus supporting the idea of independent evolutionary origin of the rostrosoma. Thelyphonida, Amblypygi and Scorpiones share the occurrence of a large epipharyngeal/epistomal sclerite with associated musculature, which is a feature that lines up with the Arachnopulmonata concept. A comparison with all Euchelicerata taxa shows that the snout region is formed by homologous morphological elements but the specific arrangement, additions and reductions shape the formation of the rostrosoma, so that parallel evolution of homologous parts of the arachnid ground pattern can be assumed that has formed those elements into convergent morphologies.</p></div>","PeriodicalId":55461,"journal":{"name":"Arthropod Structure & Development","volume":null,"pages":null},"PeriodicalIF":1.7,"publicationDate":"2024-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S1467803924000422/pdfft?md5=6841998e48ffd80f99c7ea7aa7459177&pid=1-s2.0-S1467803924000422-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141768051","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-01DOI: 10.1016/j.asd.2024.101371
Trilobites were extremely abundant and diverse euarthropods from the Paleozoic Era, but our understanding of their non-biomineralized ventral morphology is restricted to localities with exceptional fossil preservation. The Ordovician-aged Walcott-Rust Quarry in New York State preserves exceptional trilobite fossils as calcite casts in three-dimensions with little to no deformation, providing a valuable view of their ventral morphology. Appendages of the two most abundant trilobites, Ceraurus pleurexanthemus and Flexicalymene senaria, have been known for over 150 years but the original preparation of the specimens as thin sections has led to significant disagreement about their anatomy. Ceraruus pleurexanthemus is more abundant in the thin section collections (157 specimens) and features nearly complete appendages including a subtriangular protopodite with stud-like gnathobases along the medial edge and long endites ventrally. The exopodite consists of a long proximal article bearing dumbbell-shaped lamellae (in cross section) and a shorter distal article, closely resembling that of the cheirurid Anacheirurus adserai from the Lower Ordovician Fezouata Shale biota of Morocco. The appendages of F. senaria (37 specimens) are less well preserved. The exopodite bears up to 40 dumbbell shaped lamellae (in cross section) and is proportionally longer relative to the endopodite of C. pleurexanthemus. The close morphological similarity observed between the exopodites of C. pleurexanthemus and A. adersai, despite originating from paleogeographically distant latitudes and temporally separated by over ca. 20 million years, shows that the proposed “Cambrian type” exopodite persisted through the majority of the Ordovician. The morphology of the endopodites between C. pleurexanthemus and A. adersai is more variable when compared to the organization of the exopodites, may reflect selective pressures from locomotion and feeding between these species.
三叶虫是古生代数量极其丰富、种类极其繁多的类地行星,但我们对其非生物矿化腹面形态的了解仅限于化石保存特别完好的地方。纽约州奥陶纪时期的沃尔科特-拉斯特采石场(Walcott-Rust Quarry)以几乎没有变形的三维方解石铸件形式保存了特殊的三叶虫化石,为我们了解它们的腹部形态提供了宝贵的视角。150 多年前,人们就已经知道两种最丰富的三叶虫--Ceraurus pleurexanthemus 和 Flexicalymene senaria--的附肢,但由于最初将标本制作成薄片,人们对它们的解剖结构存在很大分歧。Ceraruus pleurexanthemus 在薄片标本中的数量较多(157 个标本),其特征是几乎完整的附肢,包括一个近三角形的原脚节,内侧边缘有螺柱状的钩喙,腹侧有长的内齿。外脚节由一个长的近端节和一个较短的远端节组成,近端节带有哑铃状薄片(横截面),与摩洛哥下奥陶世费祖阿塔页岩生物群中的螯足类 Anacheirurus adserai 非常相似。F. senaria(37 个标本)的附肢保存较差。外节上有多达 40 个哑铃状薄片(横截面),与 C. pleurexanthemus 的内节相比,外节的比例长度更长。尽管 C. pleurexanthemus 和 A. adersai 的外脚节起源于古地理上遥远的纬度地区,而且在时间上相隔约 2000 万年,但它们的外脚节在形态上却非常相似。这表明所提出的 "寒武纪类型 "外蜕皮一直持续到奥陶纪的大部分时期。C. pleurexanthemus 和 A. adersai 之间的内足器形态与外足器的组织相比变化更大,这可能反映了这些物种之间运动和取食的选择性压力。
{"title":"Conserved exopodite morphology in three-dimensionally preserved trilobites from the Walcott-Rust Quarry (Mohawkian, Ordovician) of New York, USA","authors":"","doi":"10.1016/j.asd.2024.101371","DOIUrl":"10.1016/j.asd.2024.101371","url":null,"abstract":"<div><p>Trilobites were extremely abundant and diverse euarthropods from the Paleozoic Era, but our understanding of their non-biomineralized ventral morphology is restricted to localities with exceptional fossil preservation. The Ordovician-aged Walcott-Rust Quarry in New York State preserves exceptional trilobite fossils as calcite casts in three-dimensions with little to no deformation, providing a valuable view of their ventral morphology. Appendages of the two most abundant trilobites, <em>Ceraurus pleurexanthemus</em> and <em>Flexicalymene senaria</em>, have been known for over 150 years but the original preparation of the specimens as thin sections has led to significant disagreement about their anatomy. <em>Ceraruus pleurexanthemus</em> is more abundant in the thin section collections (157 specimens) and features nearly complete appendages including a subtriangular protopodite with stud-like gnathobases along the medial edge and long endites ventrally. The exopodite consists of a long proximal article bearing dumbbell-shaped lamellae (in cross section) and a shorter distal article, closely resembling that of the cheirurid <em>Anacheirurus adserai</em> from the Lower Ordovician Fezouata Shale biota of Morocco. The appendages of <em>F. senaria</em> (37 specimens) are less well preserved. The exopodite bears up to 40 dumbbell shaped lamellae (in cross section) and is proportionally longer relative to the endopodite of <em>C. pleurexanthemus</em>. The close morphological similarity observed between the exopodites of <em>C. pleurexanthemus</em> and <em>A. adersai</em>, despite originating from paleogeographically distant latitudes and temporally separated by over ca. 20 million years, shows that the proposed “Cambrian type” exopodite persisted through the majority of the Ordovician. The morphology of the endopodites between <em>C. pleurexanthemus</em> and <em>A. adersai</em> is more variable when compared to the organization of the exopodites, may reflect selective pressures from locomotion and feeding between these species.</p></div>","PeriodicalId":55461,"journal":{"name":"Arthropod Structure & Development","volume":null,"pages":null},"PeriodicalIF":1.7,"publicationDate":"2024-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141732008","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-01DOI: 10.1016/j.asd.2024.101373
Schizomida is an enigmatic group of arachnids that is traditionally considered the dwarfed sister to Thelyphonida. Schizomids are of interest for evolutionary morphology, because they show a number of features like a tripartite prosoma dorsal shield (pro-, meso-, metapeltidium), formation of three sterna, a complex prosoma–opisthosoma transition and a metasoma. By analyzing the body organization of Schizomida and comparing it to Thelyphonida and other arachnids, this article provides evidence for independent evolution of some of these features in Schizomida. This supports the idea that, among arachnids, multiple and independent evolutionary pathways have resulted in similar morphologies, that conventionally have been considered shared similarities. – The analysis of serial microscopic sections and μCT-imaging of segmental indicator muscles of the prosoma evidences that the propeltidium covers prosoma segments 0–4, and the metapeltidium covers segments 5 and 6. The mesopeltidium is a dorsolateral sclerotization of the pleural membrane, not assigned to a segment, and therefore not a tergite. The topographic association of segmental musculature and sclerites of the tripartite dorsum of the prosoma differs from other taxa with such external body organization, e.g., Palpigradi and Solifugae, suggesting independent evolutionary origin. – The prosoma–opisthosoma transition integrates the first opisthosoma segment into the prosoma. The sternite of the first opisthosoma segment forms the metasternum between the coxae of the fourth pair of walking legs. The morphology of the prosoma–opisthosoma transition is similar to Uropygi and Amblypygi, but is less complex. – The morphology of the metasoma (opisthosoma segments X-XII) of Schizomida and Thelyphonida differs from that of all other arachnids carrying a metasoma, thus providing support for multiple independent evolutionary origins of metasomata.
{"title":"Comparative microscopic anatomy of Schizomida – 1. Segmental axial musculature and body organization","authors":"","doi":"10.1016/j.asd.2024.101373","DOIUrl":"10.1016/j.asd.2024.101373","url":null,"abstract":"<div><p>Schizomida is an enigmatic group of arachnids that is traditionally considered the dwarfed sister to Thelyphonida. Schizomids are of interest for evolutionary morphology, because they show a number of features like a tripartite prosoma dorsal shield (pro-, meso-, metapeltidium), formation of three sterna, a complex prosoma–opisthosoma transition and a metasoma. By analyzing the body organization of Schizomida and comparing it to Thelyphonida and other arachnids, this article provides evidence for independent evolution of some of these features in Schizomida. This supports the idea that, among arachnids, multiple and independent evolutionary pathways have resulted in similar morphologies, that conventionally have been considered shared similarities. – The analysis of serial microscopic sections and μCT-imaging of segmental indicator muscles of the prosoma evidences that the propeltidium covers prosoma segments 0–4, and the metapeltidium covers segments 5 and 6. The mesopeltidium is a dorsolateral sclerotization of the pleural membrane, not assigned to a segment, and therefore not a tergite. The topographic association of segmental musculature and sclerites of the tripartite dorsum of the prosoma differs from other taxa with such external body organization, e.g., Palpigradi and Solifugae, suggesting independent evolutionary origin. – The prosoma–opisthosoma transition integrates the first opisthosoma segment into the prosoma. The sternite of the first opisthosoma segment forms the metasternum between the coxae of the fourth pair of walking legs. The morphology of the prosoma–opisthosoma transition is similar to Uropygi and Amblypygi, but is less complex. – The morphology of the metasoma (opisthosoma segments X-XII) of Schizomida and Thelyphonida differs from that of all other arachnids carrying a metasoma, thus providing support for multiple independent evolutionary origins of metasomata.</p></div>","PeriodicalId":55461,"journal":{"name":"Arthropod Structure & Development","volume":null,"pages":null},"PeriodicalIF":1.7,"publicationDate":"2024-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S1467803924000434/pdfft?md5=0ab62a1719e4cc81d19530ce3b0bfa6f&pid=1-s2.0-S1467803924000434-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141879904","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-06-07DOI: 10.1016/j.asd.2024.101370
Maria Petrova, Ekaterina Bogomolova
Sea spiders (Pycnogonida) are marine chelicerates. Current pycnogonid phylogeny based on molecular data remains uncertain and contradicts traditional morphological perspectives. To resolve this conflict, understanding their inner anatomy is crucial. The reproductive system of sea spiders shows promise as a source of phylogenetic signal, yet our knowledge in this area is limited. This study presents the first description of the whole female reproductive system of a sea spider at the ultrastructural level. We suggest a more detailed functional regionalization of the ovary based on the ovarian wall ultrastructure and distribution of oocyte developmental stages. Meiosis begins in the germarium, and oocytes progress to the vitellarium through a transportational zone. Vitellogenic oocytes extend through the vitellarium wall, connected with it by a stalk – specialized cells. Balbiani bodies are present in early vitellogenic oocytes but dissipate later. The formation of the vitelline envelope, yolk, and fertilization envelope involves functionally diverse RER vesicles. The study also identifies a reproductive sinus as a separate haemocoel compartment that may enhance nutrient concentration near vitellogenic oocytes. Additionally, oviduct and gonopore glands are described in the female of P. femoratum, although their specific functions and prevalence in other sea spider species remain unclear.
{"title":"The female reproductive system of the sea spider Phoxichilidium femoratum (Rathke, 1799)","authors":"Maria Petrova, Ekaterina Bogomolova","doi":"10.1016/j.asd.2024.101370","DOIUrl":"https://doi.org/10.1016/j.asd.2024.101370","url":null,"abstract":"<div><p>Sea spiders (Pycnogonida) are marine chelicerates. Current pycnogonid phylogeny based on molecular data remains uncertain and contradicts traditional morphological perspectives. To resolve this conflict, understanding their inner anatomy is crucial. The reproductive system of sea spiders shows promise as a source of phylogenetic signal, yet our knowledge in this area is limited. This study presents the first description of the whole female reproductive system of a sea spider at the ultrastructural level. We suggest a more detailed functional regionalization of the ovary based on the ovarian wall ultrastructure and distribution of oocyte developmental stages. Meiosis begins in the germarium, and oocytes progress to the vitellarium through a transportational zone. Vitellogenic oocytes extend through the vitellarium wall, connected with it by a stalk – specialized cells. Balbiani bodies are present in early vitellogenic oocytes but dissipate later. The formation of the vitelline envelope, yolk, and fertilization envelope involves functionally diverse RER vesicles. The study also identifies a reproductive sinus as a separate haemocoel compartment that may enhance nutrient concentration near vitellogenic oocytes. Additionally, oviduct and gonopore glands are described in the female of <em>P</em>. <em>femoratum</em>, although their specific functions and prevalence in other sea spider species remain unclear.</p></div>","PeriodicalId":55461,"journal":{"name":"Arthropod Structure & Development","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2024-06-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141285919","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}