Fabrizio Marcondes Machado - Academia.edu (original) (raw)

Papers by Fabrizio Marcondes Machado

Invertebrate Systematics, Nov 21, 2022

The Anomalodesmata Dall, 1899 includes some of the rarest and most specialised species of marine ... more The Anomalodesmata Dall, 1899 includes some of the rarest and most specialised species of marine bivalves. This rarity has consequently constituted the greatest obstacle for understanding the internal relationships due to the low representativeness of species present in any phylogenetic reconstructions. Therefore, with the primary purpose of creating a more comprehensive morphological analysis, data including all the anomalodesmatan families were gathered into a cladistic analysis. Our data set includes, for the first-time, information about members of the families Clistoconchidae, Cetoconchidae, Protocuspidariidae, Spheniopsidae and the recently described Bentholyonsiidae. Information on shell morphology, anatomy and behaviour of anomalodesmatans was compiled through a review of the literature (from 1895 to 2022) and a re-analysis of shells and internal anatomy of some freshly collected and archived specimens in museum collections around the world. Our analysis suggests a deep division of the Anomalodesmata into two distinct clades: the first generally composed of shallow water species from 12 families and a second clade of a carnivorous lineage mainly comprising deep water species from 10 families. Consequently, a new topology for Anomalodesmata is suggested bringing new insights into the interfamilial relationships of this sometimes bizarre clade of bivalves.

Journal of Natural History, Mar 14, 2016

Spheniopsis brasiliensis, from depths of 17-148 m off the southern Atlantic coast of Brazil, is a... more Spheniopsis brasiliensis, from depths of 17-148 m off the southern Atlantic coast of Brazil, is a predator of epipsammic micro-crustaceans which it sucks into the infra-septal chamber using a raptorial inhalant siphon and internally generated hydrostatic suction forces. Prey items, which include ostracods, are thought to be pushed into the funnel-shaped mouth using the foot. The stomach is capacious with a short style sac conjoined briefly with the mid gut and possessing a stubby crystalline style. Internal stomach architecture is simplified, with no identifiable sorting areas (unlike other cuspidarioids) and lined virtually completely by a gastric shield. The exoskeletal remains of digested prey are held in the posterior end of the stomach and not in a specialised waste storage pouch as in the con-familial Grippina coronata. The mid gut, hind gut and rectum are all extremely narrow and, thus, only the smallest of faeces can be accommodated and transmitted for anal discharge. Spheniopsis brasiliensis, like G. coronata is a selffertilising simultaneous hermaphrodite with encapsulated lecithotrophic eggs brooded internally. Both taxa are thus ovovivaporous. It is also believed that both taxa are univoltine so that larvae and the exoskeletal prey remains are all released post mortem. Cuspidariids are generally regarded as dioecious but, recently, Cardiomya costellata has been shown to be a non-brooding simultaneous hermaphrodite. The distinguishing characters between cuspidariids and spheniopsids thus appear to be their differing reproductive strategies and life history traits.

Advances in Marine Biology, 2019

Most bivalves are suspension feeders. On the deep sea floor, however, some are predators, typical... more Most bivalves are suspension feeders. On the deep sea floor, however, some are predators, typically of meiobenthic crustaceans: copepods, cumaceans and ostracods. Propeamusiid scallops are one such group of predators. The largest numbers of predators, however, belong to the bivalve subclass Anomalodesmata and constitute, as currently recognised, some 500 species belonging principally to the Verticordioidea (120), Poromyoidea (75) and Cuspidarioidea (304) with four, two and four constituent families, respectively. A further family, the Parilimyidae, is considered to be derived from the Pholadomyoidea-the anomalodesmatan ancestor. These, generally small (<60mm shell length), nacreous and thin-shelled predators share many anatomical features that formerly allowed them to be collectively classified as the Septibranchia. Although this name is now rarely used, it refers to their possession of a ctenidially-derived septum in the mantle cavity and functioning in prey capture. Generally, there is a trend, possibly evolutionary, from a typical bivalve ctenidium (Parilimyidae and some Verticordioidea) to a complete septum (other Verticordioidea, Poromyoidea and Cuspidarioidea). In addition, the inhalant siphon, foot, labial palps, mouth and its lips play a role in prey capture, and ingestion. Similarly, the stomach is modified to digest such, typically chitinous, ingested prey. Most septibranchs are either consecutive or simultaneous hermaphrodites with self-fertilisation possibly usual and with some evidence in a few of larval brooding. Notwithstanding, the deep sea septibranch species are poorly studied with virtually nothing being known about their wider distributions, ecology, detailed reproductive strategies and life history traits.

American Malacological Bulletin, May 1, 2015

The Spheniopsidae Gardner, 1928 comprises four living species of Spheniopsis Sandberger, 1861 and... more The Spheniopsidae Gardner, 1928 comprises four living species of Spheniopsis Sandberger, 1861 and eight of Grippina Dall, 1912, the latter restricted to the Pacifi c Ocean, the former also occurring in the Atlantic. Spheniopsis brasiliensis new species and Grippina coronata new species are described from the Brazilian southeastern coast, based on a detailed study of their shells. They are distinguished from already described species mainly by differences in the outline of the valves, external sculpture and right hinge dentition. Shallow micro-pits present all over the outer surface of the dissoconch are viewed as similar to those already described for cuspidariids. They may, thus, represent further evidence for the relatedness of spheniopsids and cuspidarioideans. The new species from Brazil represent the fi rst fi nding of these rare minute bivalves of this family from the southwestern Atlantic.

Journal of the Marine Biological Association of the United Kingdom, Apr 27, 2016

Of the more than 800 Recent species of Anomalodesmata only 16 have been studied alive. The Septib... more Of the more than 800 Recent species of Anomalodesmata only 16 have been studied alive. The Septibranchia, comprising a number of carnivorous bivalve superfamilies, are no exception to this generalization and, until recently, no living member of this group has been studied since the 1980s. Collected from the shallow, shelf seabed off Brazil, Cardiomya cleryana is one of only a few species to have its morphology described in recent years and the first ever anomalodesmatan to be filmed alive. Important anatomical features such as a greatly extensible foot to secure itself in the sediment with a single byssal thread, exhalant siphon inter-tentacular projections and micro-papillae on the surface of the siphonal tentacles are described. Observations on the species' behaviour have revealed a lifestyle hitherto not recorded for any septibranch, indeed any anomalodesmatan. The anchoring mechanism of C. cleryana using an extraordinarily long byssal thread is described for the first time. The life position of C. cleryana is at 458 to the sediment-water interface whereas other cuspidariids have been considered to orient themselves vertically. An anatomical comparison between Cardiomya and Bathyneaera has revealed close affinities. This study thus provides new insights into the morphology and behaviour of the Cuspidariidae.

Considerado um grupo monofilético, os Anomalodesmata Dall, 1889 possuem atualmente mais de 800 es... more Considerado um grupo monofilético, os Anomalodesmata Dall, 1889 possuem atualmente mais de 800 espécies, abrigando alguns dos bivalves marinhos mais raros, bizarros e especializados. Essa raridade aliada a uma carência de informações anatômicas detalhadas sobre suas espécies sempre foram obstáculos para a compreensão de suas relações internas, consequentemente, resultando também em uma baixa representatividade de táxons em reconstruções filogenéticas. Com o intuito de preencher algumas das principais lacunas no conhecimento dos Anomalodesmata, a presente Tese propôs três objetivos específicos, buscando, através de diferentes ferramentas, ampliar, atualizar e apresentar novas idéias ao conhecimento evolutivo, morfológico e taxonômico desse importante grupo de bivalves. O primeiro objetivo se deu por meio de coletas realizadas na Baía do Araçá, litoral Norte do Estado de São Paulo, onde foi possível observar e descrever em detalhes a morfologia funcional e o comportamento de Cardiomya cleryana, trazendo novos insights sobre os bivalves carnívoros como um todo. O segundo objetivo foi realizado por meio do acesso à coleção malacológica do Museum of Comparative Zoology-Harvard University, onde grande parte dos lotes depositados nessa instituição foram revisados, gerando novos dados conquiliológicos e anatômicos para a elaboração de uma análise morfológica, gerando uma nova filogenia para os Anomalodesmata. Por fim, o terceiro objetivo versou sobre o uso de microtomógrafos de raios-x para ampliar o conhecimento anatômico dos anomalodesmados, culminando nos primeiros protocolos de contraste para bivalves marinhos, comparações entre diferentes técnicas invasivas, além das primeiras descrições anatômicas de bivalves baseadas exclusivamente em imagens tomográficas e reconstruções 3D.

Invertebrate Systematics

The Anomalodesmata Dall, 1899 includes some of the rarest and most specialised species of marine ... more The Anomalodesmata Dall, 1899 includes some of the rarest and most specialised species of marine bivalves. This rarity has consequently constituted the greatest obstacle for understanding the internal relationships due to the low representativeness of species present in any phylogenetic reconstructions. Therefore, with the primary purpose of creating a more comprehensive morphological analysis, data including all the anomalodesmatan families were gathered into a cladistic analysis. Our data set includes, for the first-time, information about members of the families Clistoconchidae, Cetoconchidae, Protocuspidariidae, Spheniopsidae and the recently described Bentholyonsiidae. Information on shell morphology, anatomy and behaviour of anomalodesmatans was compiled through a review of the literature (from 1895 to 2022) and a re-analysis of shells and internal anatomy of some freshly collected and archived specimens in museum collections around the world. Our analysis suggests a deep divi...

Acta Zoologica, 1992

Anomalodesmata is composed exclusively of marine bivalves, which occupy a wide range of habitats ... more Anomalodesmata is composed exclusively of marine bivalves, which occupy a wide range of habitats from the intertidal zone to deep waters, where they have adopted a variety of lifestyles (Morton, 1985). Most species are now restricted to relatively limited geographic ranges and have specialized niches being, therefore, considered a group of rare species (

American Malacological Bulletin, 2016

a new combination to S. obliquus does not occur in Brazilian waters. Therefore, one of these Braz... more a new combination to S. obliquus does not occur in Brazilian waters. Therefore, one of these Brazilian solenids remains without a formal description probably being a putative new species. Some species of this family have a high commercial value in several Asian and European countries. In Japan and China, particularly, these bivalves are appreciated for their nutritional value as in the case of Solen gordonis Yokohama, 1920, which is collected by inhabitants for food and Solen

Figure 3. Spheniopsis brasiliensis. A ventral view of the septum, foot and mouth. BG, Byssal groo... more Figure 3. Spheniopsis brasiliensis. A ventral view of the septum, foot and mouth. BG, Byssal groove; F, foot; F(T), 'toe' of foot; M, mouth; SE, septum; SEM, margin of septal membrane; SEP(1),(2),(3),(4), septal pores.

Figure 10. Spheniopsis brasiliensis. A transverse section through the heart. AM, Amoebocyte; AU, ... more Figure 10. Spheniopsis brasiliensis. A transverse section through the heart. AM, Amoebocyte; AU, auricle; PE, pericardium; PEG, pericardial gland; R, rectum; SM, suspensory membrane; V, ventricle.

Figure 5. Spheniopsis brasiliensis. Transverse sections through the (A) oesophagous; (B) crystall... more Figure 5. Spheniopsis brasiliensis. Transverse sections through the (A) oesophagous; (B) crystalline style sac; (C) mid gut; (D) hind gut; and (E) rectum, all drawn to the same scale. CC, Collagen coat; CS, crystalline style.

Figure 11. Spheniopsis brasiliensis. A transverse section through the rectum, showing minute frag... more Figure 11. Spheniopsis brasiliensis. A transverse section through the rectum, showing minute fragments of ingested and digested prey items. AM, Amoebocyte; CIC, ciliated cell; FIPI, fragment of ingested prey item.

Figure 13. Illustrations of prey capture by (A) Grippina coronata; (B) Spheniopsis brasiliensis; ... more Figure 13. Illustrations of prey capture by (A) Grippina coronata; (B) Spheniopsis brasiliensis; and (C) Cuspidaria rostrata, all drawn to approximately the same scale. (A redrawn partly after Morton et al. (2015, fig. 24 C) and C redrawn partly after Reid and Reid (1974, fig. 1). Possible prey items are also identified. The arrows show how evolution of the rostrum has allowed deeper residence of the sediments presumably for enhanced protection.

Figure 6. Spheniopsis brasiliensis. A transverse section through the visceral mass, towards the p... more Figure 6. Spheniopsis brasiliensis. A transverse section through the visceral mass, towards the posterior end of the stomach and illustrating the disposition of the paired gonads. APRM, Anterior septal retractor muscles; DT, digestive tubule; EO, encapsulated oocyte; FIPI, fragment of ingested prey item; GF, gonadial follicle; IPI, ingested prey item; SC, secretory cells.

Figure 2. Spheniopsis brasiliensis. The organs of the mantle cavity and visceral mass, as seen fr... more Figure 2. Spheniopsis brasiliensis. The organs of the mantle cavity and visceral mass, as seen from the right side after removal of the right shell valve and mantle lobe. AAM, anterior adductor muscle; AN, anus; APRM, anterior pedal retractor muscle; ASRM, anterior septal retractor muscle; AU, auricle; CS, crystalline style; CSS, crystalline style sac; DD, digestive diverticulae; EO, encapsulated oocyte; F, foot; G, gonad; HG, hind gut; M, mouth; MG, mid gut; PAM, posterior adductor muscle; PE, pericardium; PEG, pericardial gland; PL, pallial line; PPRM, posterior pedal retractor muscle; PR, prodissoconch; PS, pallial sinus; PSRM, posterior septal retractor muscle; SE, Septum; ST, stomach.

Figure 7. Spheniopsis brasiliensis. Histological sections through the visceral mass and ingested ... more Figure 7. Spheniopsis brasiliensis. Histological sections through the visceral mass and ingested prey items. (A) A transverse section through the stomach with ingested prey items inside it. (B, C) The remains of captured and ingested ostracods. (D) The skeletal remains of an unknown prey item. CSS, Crystalline style sac; GS, gastric shield; IPI, ingested prey item; ST, stomach.

Figure 4. Spheniopsis brasiliensis. A transverse section through the stomach in the region of the... more Figure 4. Spheniopsis brasiliensis. A transverse section through the stomach in the region of the conjoined style sac and mid gut. CS, Crystalline style; CSMG, conjoined style sac and mid gut; CSS, crystalline style sac; FIPI, fragments of ingested prey; GS, gastric shield; MG, mid gut; SC, secretory cells.

Invertebrate Systematics, Nov 21, 2022

The Anomalodesmata Dall, 1899 includes some of the rarest and most specialised species of marine ... more The Anomalodesmata Dall, 1899 includes some of the rarest and most specialised species of marine bivalves. This rarity has consequently constituted the greatest obstacle for understanding the internal relationships due to the low representativeness of species present in any phylogenetic reconstructions. Therefore, with the primary purpose of creating a more comprehensive morphological analysis, data including all the anomalodesmatan families were gathered into a cladistic analysis. Our data set includes, for the first-time, information about members of the families Clistoconchidae, Cetoconchidae, Protocuspidariidae, Spheniopsidae and the recently described Bentholyonsiidae. Information on shell morphology, anatomy and behaviour of anomalodesmatans was compiled through a review of the literature (from 1895 to 2022) and a re-analysis of shells and internal anatomy of some freshly collected and archived specimens in museum collections around the world. Our analysis suggests a deep division of the Anomalodesmata into two distinct clades: the first generally composed of shallow water species from 12 families and a second clade of a carnivorous lineage mainly comprising deep water species from 10 families. Consequently, a new topology for Anomalodesmata is suggested bringing new insights into the interfamilial relationships of this sometimes bizarre clade of bivalves.

Journal of Natural History, Mar 14, 2016

Spheniopsis brasiliensis, from depths of 17-148 m off the southern Atlantic coast of Brazil, is a... more Spheniopsis brasiliensis, from depths of 17-148 m off the southern Atlantic coast of Brazil, is a predator of epipsammic micro-crustaceans which it sucks into the infra-septal chamber using a raptorial inhalant siphon and internally generated hydrostatic suction forces. Prey items, which include ostracods, are thought to be pushed into the funnel-shaped mouth using the foot. The stomach is capacious with a short style sac conjoined briefly with the mid gut and possessing a stubby crystalline style. Internal stomach architecture is simplified, with no identifiable sorting areas (unlike other cuspidarioids) and lined virtually completely by a gastric shield. The exoskeletal remains of digested prey are held in the posterior end of the stomach and not in a specialised waste storage pouch as in the con-familial Grippina coronata. The mid gut, hind gut and rectum are all extremely narrow and, thus, only the smallest of faeces can be accommodated and transmitted for anal discharge. Spheniopsis brasiliensis, like G. coronata is a selffertilising simultaneous hermaphrodite with encapsulated lecithotrophic eggs brooded internally. Both taxa are thus ovovivaporous. It is also believed that both taxa are univoltine so that larvae and the exoskeletal prey remains are all released post mortem. Cuspidariids are generally regarded as dioecious but, recently, Cardiomya costellata has been shown to be a non-brooding simultaneous hermaphrodite. The distinguishing characters between cuspidariids and spheniopsids thus appear to be their differing reproductive strategies and life history traits.

Advances in Marine Biology, 2019

Most bivalves are suspension feeders. On the deep sea floor, however, some are predators, typical... more Most bivalves are suspension feeders. On the deep sea floor, however, some are predators, typically of meiobenthic crustaceans: copepods, cumaceans and ostracods. Propeamusiid scallops are one such group of predators. The largest numbers of predators, however, belong to the bivalve subclass Anomalodesmata and constitute, as currently recognised, some 500 species belonging principally to the Verticordioidea (120), Poromyoidea (75) and Cuspidarioidea (304) with four, two and four constituent families, respectively. A further family, the Parilimyidae, is considered to be derived from the Pholadomyoidea-the anomalodesmatan ancestor. These, generally small (<60mm shell length), nacreous and thin-shelled predators share many anatomical features that formerly allowed them to be collectively classified as the Septibranchia. Although this name is now rarely used, it refers to their possession of a ctenidially-derived septum in the mantle cavity and functioning in prey capture. Generally, there is a trend, possibly evolutionary, from a typical bivalve ctenidium (Parilimyidae and some Verticordioidea) to a complete septum (other Verticordioidea, Poromyoidea and Cuspidarioidea). In addition, the inhalant siphon, foot, labial palps, mouth and its lips play a role in prey capture, and ingestion. Similarly, the stomach is modified to digest such, typically chitinous, ingested prey. Most septibranchs are either consecutive or simultaneous hermaphrodites with self-fertilisation possibly usual and with some evidence in a few of larval brooding. Notwithstanding, the deep sea septibranch species are poorly studied with virtually nothing being known about their wider distributions, ecology, detailed reproductive strategies and life history traits.

American Malacological Bulletin, May 1, 2015

The Spheniopsidae Gardner, 1928 comprises four living species of Spheniopsis Sandberger, 1861 and... more The Spheniopsidae Gardner, 1928 comprises four living species of Spheniopsis Sandberger, 1861 and eight of Grippina Dall, 1912, the latter restricted to the Pacifi c Ocean, the former also occurring in the Atlantic. Spheniopsis brasiliensis new species and Grippina coronata new species are described from the Brazilian southeastern coast, based on a detailed study of their shells. They are distinguished from already described species mainly by differences in the outline of the valves, external sculpture and right hinge dentition. Shallow micro-pits present all over the outer surface of the dissoconch are viewed as similar to those already described for cuspidariids. They may, thus, represent further evidence for the relatedness of spheniopsids and cuspidarioideans. The new species from Brazil represent the fi rst fi nding of these rare minute bivalves of this family from the southwestern Atlantic.

Journal of the Marine Biological Association of the United Kingdom, Apr 27, 2016

Of the more than 800 Recent species of Anomalodesmata only 16 have been studied alive. The Septib... more Of the more than 800 Recent species of Anomalodesmata only 16 have been studied alive. The Septibranchia, comprising a number of carnivorous bivalve superfamilies, are no exception to this generalization and, until recently, no living member of this group has been studied since the 1980s. Collected from the shallow, shelf seabed off Brazil, Cardiomya cleryana is one of only a few species to have its morphology described in recent years and the first ever anomalodesmatan to be filmed alive. Important anatomical features such as a greatly extensible foot to secure itself in the sediment with a single byssal thread, exhalant siphon inter-tentacular projections and micro-papillae on the surface of the siphonal tentacles are described. Observations on the species' behaviour have revealed a lifestyle hitherto not recorded for any septibranch, indeed any anomalodesmatan. The anchoring mechanism of C. cleryana using an extraordinarily long byssal thread is described for the first time. The life position of C. cleryana is at 458 to the sediment-water interface whereas other cuspidariids have been considered to orient themselves vertically. An anatomical comparison between Cardiomya and Bathyneaera has revealed close affinities. This study thus provides new insights into the morphology and behaviour of the Cuspidariidae.

Considerado um grupo monofilético, os Anomalodesmata Dall, 1889 possuem atualmente mais de 800 es... more Considerado um grupo monofilético, os Anomalodesmata Dall, 1889 possuem atualmente mais de 800 espécies, abrigando alguns dos bivalves marinhos mais raros, bizarros e especializados. Essa raridade aliada a uma carência de informações anatômicas detalhadas sobre suas espécies sempre foram obstáculos para a compreensão de suas relações internas, consequentemente, resultando também em uma baixa representatividade de táxons em reconstruções filogenéticas. Com o intuito de preencher algumas das principais lacunas no conhecimento dos Anomalodesmata, a presente Tese propôs três objetivos específicos, buscando, através de diferentes ferramentas, ampliar, atualizar e apresentar novas idéias ao conhecimento evolutivo, morfológico e taxonômico desse importante grupo de bivalves. O primeiro objetivo se deu por meio de coletas realizadas na Baía do Araçá, litoral Norte do Estado de São Paulo, onde foi possível observar e descrever em detalhes a morfologia funcional e o comportamento de Cardiomya cleryana, trazendo novos insights sobre os bivalves carnívoros como um todo. O segundo objetivo foi realizado por meio do acesso à coleção malacológica do Museum of Comparative Zoology-Harvard University, onde grande parte dos lotes depositados nessa instituição foram revisados, gerando novos dados conquiliológicos e anatômicos para a elaboração de uma análise morfológica, gerando uma nova filogenia para os Anomalodesmata. Por fim, o terceiro objetivo versou sobre o uso de microtomógrafos de raios-x para ampliar o conhecimento anatômico dos anomalodesmados, culminando nos primeiros protocolos de contraste para bivalves marinhos, comparações entre diferentes técnicas invasivas, além das primeiras descrições anatômicas de bivalves baseadas exclusivamente em imagens tomográficas e reconstruções 3D.

Invertebrate Systematics

The Anomalodesmata Dall, 1899 includes some of the rarest and most specialised species of marine ... more The Anomalodesmata Dall, 1899 includes some of the rarest and most specialised species of marine bivalves. This rarity has consequently constituted the greatest obstacle for understanding the internal relationships due to the low representativeness of species present in any phylogenetic reconstructions. Therefore, with the primary purpose of creating a more comprehensive morphological analysis, data including all the anomalodesmatan families were gathered into a cladistic analysis. Our data set includes, for the first-time, information about members of the families Clistoconchidae, Cetoconchidae, Protocuspidariidae, Spheniopsidae and the recently described Bentholyonsiidae. Information on shell morphology, anatomy and behaviour of anomalodesmatans was compiled through a review of the literature (from 1895 to 2022) and a re-analysis of shells and internal anatomy of some freshly collected and archived specimens in museum collections around the world. Our analysis suggests a deep divi...

Acta Zoologica, 1992

Anomalodesmata is composed exclusively of marine bivalves, which occupy a wide range of habitats ... more Anomalodesmata is composed exclusively of marine bivalves, which occupy a wide range of habitats from the intertidal zone to deep waters, where they have adopted a variety of lifestyles (Morton, 1985). Most species are now restricted to relatively limited geographic ranges and have specialized niches being, therefore, considered a group of rare species (

American Malacological Bulletin, 2016

a new combination to S. obliquus does not occur in Brazilian waters. Therefore, one of these Braz... more a new combination to S. obliquus does not occur in Brazilian waters. Therefore, one of these Brazilian solenids remains without a formal description probably being a putative new species. Some species of this family have a high commercial value in several Asian and European countries. In Japan and China, particularly, these bivalves are appreciated for their nutritional value as in the case of Solen gordonis Yokohama, 1920, which is collected by inhabitants for food and Solen

Figure 3. Spheniopsis brasiliensis. A ventral view of the septum, foot and mouth. BG, Byssal groo... more Figure 3. Spheniopsis brasiliensis. A ventral view of the septum, foot and mouth. BG, Byssal groove; F, foot; F(T), 'toe' of foot; M, mouth; SE, septum; SEM, margin of septal membrane; SEP(1),(2),(3),(4), septal pores.

Figure 10. Spheniopsis brasiliensis. A transverse section through the heart. AM, Amoebocyte; AU, ... more Figure 10. Spheniopsis brasiliensis. A transverse section through the heart. AM, Amoebocyte; AU, auricle; PE, pericardium; PEG, pericardial gland; R, rectum; SM, suspensory membrane; V, ventricle.

Figure 5. Spheniopsis brasiliensis. Transverse sections through the (A) oesophagous; (B) crystall... more Figure 5. Spheniopsis brasiliensis. Transverse sections through the (A) oesophagous; (B) crystalline style sac; (C) mid gut; (D) hind gut; and (E) rectum, all drawn to the same scale. CC, Collagen coat; CS, crystalline style.

Figure 11. Spheniopsis brasiliensis. A transverse section through the rectum, showing minute frag... more Figure 11. Spheniopsis brasiliensis. A transverse section through the rectum, showing minute fragments of ingested and digested prey items. AM, Amoebocyte; CIC, ciliated cell; FIPI, fragment of ingested prey item.

Figure 13. Illustrations of prey capture by (A) Grippina coronata; (B) Spheniopsis brasiliensis; ... more Figure 13. Illustrations of prey capture by (A) Grippina coronata; (B) Spheniopsis brasiliensis; and (C) Cuspidaria rostrata, all drawn to approximately the same scale. (A redrawn partly after Morton et al. (2015, fig. 24 C) and C redrawn partly after Reid and Reid (1974, fig. 1). Possible prey items are also identified. The arrows show how evolution of the rostrum has allowed deeper residence of the sediments presumably for enhanced protection.

Figure 6. Spheniopsis brasiliensis. A transverse section through the visceral mass, towards the p... more Figure 6. Spheniopsis brasiliensis. A transverse section through the visceral mass, towards the posterior end of the stomach and illustrating the disposition of the paired gonads. APRM, Anterior septal retractor muscles; DT, digestive tubule; EO, encapsulated oocyte; FIPI, fragment of ingested prey item; GF, gonadial follicle; IPI, ingested prey item; SC, secretory cells.

Figure 2. Spheniopsis brasiliensis. The organs of the mantle cavity and visceral mass, as seen fr... more Figure 2. Spheniopsis brasiliensis. The organs of the mantle cavity and visceral mass, as seen from the right side after removal of the right shell valve and mantle lobe. AAM, anterior adductor muscle; AN, anus; APRM, anterior pedal retractor muscle; ASRM, anterior septal retractor muscle; AU, auricle; CS, crystalline style; CSS, crystalline style sac; DD, digestive diverticulae; EO, encapsulated oocyte; F, foot; G, gonad; HG, hind gut; M, mouth; MG, mid gut; PAM, posterior adductor muscle; PE, pericardium; PEG, pericardial gland; PL, pallial line; PPRM, posterior pedal retractor muscle; PR, prodissoconch; PS, pallial sinus; PSRM, posterior septal retractor muscle; SE, Septum; ST, stomach.

Figure 7. Spheniopsis brasiliensis. Histological sections through the visceral mass and ingested ... more Figure 7. Spheniopsis brasiliensis. Histological sections through the visceral mass and ingested prey items. (A) A transverse section through the stomach with ingested prey items inside it. (B, C) The remains of captured and ingested ostracods. (D) The skeletal remains of an unknown prey item. CSS, Crystalline style sac; GS, gastric shield; IPI, ingested prey item; ST, stomach.

Figure 4. Spheniopsis brasiliensis. A transverse section through the stomach in the region of the... more Figure 4. Spheniopsis brasiliensis. A transverse section through the stomach in the region of the conjoined style sac and mid gut. CS, Crystalline style; CSMG, conjoined style sac and mid gut; CSS, crystalline style sac; FIPI, fragments of ingested prey; GS, gastric shield; MG, mid gut; SC, secretory cells.