Chaetae and chaetogenesis in polychaetes (Annelida)

Hausen, Harald

doi:10.1007/1-4020-3240-4_4

Cited by 53 publications

(104 citation statements)

References 44 publications

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“…They constitute the most thoroughly studied annelid structures (for references see Fauchald, 1995, 1997;Westheide, 1997;Rouse and Pleijel, 2001;Hausen, 2005a). Chaetae have various functions and may aid in locomotion on the substrate, anchoring the body inside the tubes, protecting and defending the body, supporting parapodia, etc.…”

Section: Chaetae and Parapodiamentioning

confidence: 99%

“…The number of segments varies between species and may comprise between only 6 or fewer (e. g. Parapodrilus psammophilus Westheide, 1965) to more than 1,000 segments (e. g. Eunice aphroditois (Pallas, 1788)) resulting in body lengths varying from less than 600 µm to about 6 m (see Paxton, 2000). Presence of segmentally arranged chitinous chaetae is another key-character of annelids (Hausen, 2005a). However, the pleisomorphic condition regarding shape and structure of these chaetae and whether these chaetae were primarily situated in lobe-like appendages, the parapodia, is also a matter of discussion Struck, 2011).…”

Section: Introductionmentioning

confidence: 99%

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Systematics, evolution and phylogeny of Annelida – a morphological perspective

Purschke¹,

Bleidorn²,

Struck³

2014

Mem. Mus. Vic.

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Purschke, G., Bleidorn, C. and Struck, T. 2014. Systematics, evolution and phylogeny of Annelida -a morphological perspective . Memoirs of Museum Victoria 71: 247-269.Annelida, traditionally divided into Polychaeta and Clitellata, is an evolutionary ancient and ecologically important group today usually considered to be monophyletic. However, there is a long debate regarding the in-group relationships as well as the direction of evolutionary changes within the group. This debate is correlated to the extraordinary evolutionary diversity of this group. Although annelids may generally be characterised as organisms with multiple repetitions of identically organised segments and usually bearing certain other characters such as a collagenous cuticle, chitinous chaetae or nuchal organs, none of these are present in every subgroup. This is even true for the annelid key character, segmentation. The first morphology-based cladistic analyses of polychaetes showed Polychaeta and Clitellata as sister groups. The former were divided into Scolecida and Palpata comprising Aciculata and Canalipalpata. This systematisation definitely replaced the old concept of dividing polychaetes into Errantia and Sedentaria, whereas the group Archiannelida had already been abandoned. The main critics came from a contradicting hypothesis relying on scenario based on plausibility considerations regarding Clitellata as highly derived annelids nesting within polychaetes and rendering the latter paraphyletic. In this hypothesis the absences of typical polychaete characters were regarded as losses rather than as primary absences. However, to date attempts to unambiguously identify the sister group of Clitellata on the basis of morphological characters have failed. Thus, two hypotheses on the last common annelid ancestor have been put forward either being an oligochaete-like burrowing animal or a parapodia-bearing epibenthic worm. These attempts to understand the major transitions in annelid evolution are reviewed and discussed in the light of new morphological evidence such as photoreceptor cell and eye evolution as well as the evolution of the nervous system and musculature. We also discuss the plausibility of these scenarios with regard to recent advances in molecular phylogenetic analyses.

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Section: Chaetae and Parapodiamentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Systematics, evolution and phylogeny of Annelida – a morphological perspective

Purschke¹,

Bleidorn²,

Struck³

2014

Mem. Mus. Vic.

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“…jouinae (Brown, 1981); P. tridentiger (Brown, 1981); P. uchidai 865 (Sasaki, 1981); P. goodrichi (Jouin-Toulmond and Gambi, 2007); P. Altschul et al (1997), Barnes (2002), Dordel et al (2010), Gelder 913 and Palmer (1976), Giere (2009), Hausen (2005, Ingólfsson (1995), 914 Katoh and Toh (2008), Orrhage (1974), Rosenzweig (1995), 915 Stamatakis et al (2008), Struck (2011Struck ( , 2007, Struck et al (2011), 916 Tamura et al (2007), Todaro et al (1996), des (2001) and Westheide and Rieger (1987 …”

mentioning

confidence: 99%

Molecular and morphological phylogeny of Saccocirridae (Annelida) reveals two cosmopolitan clades with specific habitat preferences

Domênico

Martínez

Lana

et al. 2014

Molecular Phylogenetics and Evolution

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“…New chaetae are always formed at the ventral edge of the rows. The same arrangement is known for many sedentary polychaetes (Hausen, 2005). Notopodial transverse rows with a ventral formative site have been shown throughout the body for members of Spionidae (Hausen and Bartolomaeus, 1998;Radashevsky and Fauchald, 2000), Capitellidae (Schweigkofler et al, 1998), Magelonidae, Paraonidae, and Cirratulidae (Hausen, 2001).…”

Section: Discussionmentioning

confidence: 62%

“…The value of chaetal characters for systematic studies has been shown for several polychaete taxa (Bartolomaeus, 1998;Hausen and Bartolomaeus, 1998;Hausen, 2005). In Maldanidae the parapodia are usually developed as small extensions of the body wall.…”

Section: Introductionmentioning

confidence: 99%

Significance of chaetal arrangement for maldanid systematics (Annelida, Maldanidae)

Hausen¹,

Bleidorn

2006

Sci. Mar.

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SUMMARY: Maldanids are usually divided into several subfamilies: Euclymeninae, Lumbriclymeninae, Maldaninae, Nicomachinae, Rhodininae, Clymenurinae, Notoproctinae, and Boguinae. The taxonomy of maldanids and the delimination of these taxa are mainly based on head morphology, total number of segments, chaetal structure, shape of the pygidium, and position of the anus. The maldanid ingroup relationships, as well as the monophyly of the proposed subfamilies, have so far not been investigated. Pilgrim (1977) described a shift of the notopodial chaetal rows from a transverse direction in anterior chaetigers to a more longitudinal one in posterior chaetigers in Clymene torquata (Leidy, 1855) and Euclymene oerstedii (Claparède, 1863), both belonging to the Euclymeninae. We investigated several maldanid species to assess the usefulness of this character for maldanid systematics and used 3D-reconstruction techniques to reveal the complete geometry of the chaetal sacs. Our investigation shows that a shift is apparent in Euclymene, Axiothella, Johnstonia (all Euclymeninae) and Clymenura (Clymenurinae), but absent in species like Maldane sarsi (Malmgren, 1865), Metasychis disparidentata (Moore, 1904) (both Maldaninae) and Petaloproctus borealis Ardwisson, 1906 (Nicomachinae). The shift is not typical for sedentary polychaetes and is apomorphic within maldanid polychaetes. It thus argues for a close relationship between Euclymeninae and Clymenurinae. The investigation of further maldanid species of different subfamilies may shed additional light on maldanid systematics.Keywords: Annelida, Polychaeta, Maldanidae, systematics, chaetae, chaetal arrangement. RESUMEN: EL SIGNIFICADO DE LA DISPOSICIÓN DE LAS QUETAS EN LA SISTEMÁTICA DE LOS MALDÁNIDOS (ANNELIDA: MALDANIDAE). -Los Maldánidos se clasifican usualmente en ocho subfamilias: Euclymeninae, Lumbriclymeninae, Maldaninae, Nicomachinae, Rhodininae, Clymenurinae, Notoproctinae, y Boguinae. La taxonomía de esta familia está basada en la morfología del prostómio, el número total de segmentos, la estructura de las quetas, la forma del pigidio y la posición del ano. Sin embargo, las relaciones dentro del grupo de los maldánidos , así como la monofília de las subfamilias propuestas, no han sido aún investigadas. Pilgrim (1977) describió en Clymene torquata (Leidy, 1855) y Euclymene oerstedii (Claparède, 1863), ambos pertenecientes a Euclymeninae, un cambio en la orientación de las filas de quetas notopodiales desde una poción transversal en los setígeros anteriores a una posición más longitudinal en los setígeros posteriores. En este trabajo se ha investigado el carácter anterior en diversas especies de maldánidos para ver si podría ser usado en la sistemá-tica del grupo, usando reconstrucciones en tres dimensiones para observar la completa geometría de las bolsas de quetas, Nuestras investigaciones muestran que dichos cambios son aparentes en Euclymene, Axiothella, Johnstonia (todos Euclymeninae) y en Clymenura (Clymenurinae), pero no se presentan en especies como Maldane sarsi (...

show abstract

Chaetae and chaetogenesis in polychaetes (Annelida)

Cited by 53 publications

References 44 publications

Systematics, evolution and phylogeny of Annelida – a morphological perspective

Systematics, evolution and phylogeny of Annelida – a morphological perspective

Molecular and morphological phylogeny of Saccocirridae (Annelida) reveals two cosmopolitan clades with specific habitat preferences

Significance of chaetal arrangement for maldanid systematics (Annelida, Maldanidae)

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