Larval development and the formation of the gut of<i>Siboglinum poseidoni</i>Flügel &amp; Langhof (Pogonophora, Perviata). Evidence of protostomian affinity

Callsen-Cencic, Peter; Flügel, H.

doi:10.1080/00364827.1995.10413582

Cited by 32 publications

(56 citation statements)

References 19 publications

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“…Called tentacles in Southward (1993). Arising behind the prototroch, the position and morphology of these structures are strikingly similar to the peristomial grooved palps of many polychaete groups and (see Bakke 1980;Southward 1988;Callsen-Cencic & Flügel 1995). It is assumed here that the plesiomorphic condition for the group is to have a pair of palps as in the genera Nereilum.…”

Section: Sperm Morphology No Mitochondrial Interpolation (Jamieson 1mentioning

confidence: 84%

Cladistics and polychaetes

1997

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A series of cladistic analyses assesses the status and membership of the taxon Polychaeta. The available literature, and a review by Fauchald & Rouse (1997), on the 80 accepted families of the Polychaeta are used to develop characters and data matrices. As well as the polychaete families, non‐polychaete taxa, such as the Echiura, Euarthropoda, Onychophora, Pogonophora (as Frenulata and Vestimentifera), Clitellata, Aeolosomatidae and Potamodrilidae, are included in the analyses. All trees are rooted using the Sipuncula as outgroup. Characters are based on features (where present) such as the prostomium, peristomium, antennae, palps, nuchal organs, parapodia, stomodaeum, segmental organ structure and distribution, circulation and chaetae. A number of analyses are performed, involving different ways of coding and weighting the characters, as well as the number of taxa included. Transformation series are provided for several of these analyses. One of the analyses is chosen to provide a new classification. The Annelida is found to be monophyletic, though weakly supported, and comprises the Clitellata and Polychaeta. The Polychaeta is monophyletic only if taxa such as the Pogonophora, Aeolosomatidae and Potamodrilidae are included and is also weakly supported. The Pogonophora is reduced to the rank of family within the Polychaeta and reverts to the name Siboglinidae Caullery, 1914. The new classification does not use Linnaean categories, and the Polychaeta comprises two clades, the Scolecida and Palpata. The Palpata has the clades Aciculata and Canalipalpata. The Aciculata contains the Phyllodocida and Eunicida. The Canalipalpata has three clades; the Sabellida (including the Siboglinidae) Spionida and Terebellida. The position of a number of families requires further investigation.

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Section: Sperm Morphology No Mitochondrial Interpolation (Jamieson 1mentioning

confidence: 84%

Cladistics and polychaetes

1997

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“…In Vestimentifera and Frenulata, a stomodaeum is absent in the adults, since the digestive tract is closed anteriorly (and posteriorly); a strand of tissue running through the brain might be considered a remnant of the stomodaeum, but this relationship has yet to be accurately traced and must await detailing of the structure of the larval stomodaeum (Jones & Gardiner 1988;Southward 1988;Callsen-Cencic & Flügel 1995) and the fate of the various tissues of the anterior end during ontogenesis.…”

Section: Stomodaeummentioning

confidence: 99%

Polychaete systematics: Past and present

1997

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In this paper, we first demonstrate the historical background for the current unsatisfactory state of systematics of the polychaetes. We then briefly discuss our knowledge of internal and external structures. A review of the polychaete families makes up the third section; 81 families are treated in detail. Five families have been recently synonymized with others, and six families are too poorly known to be sufficiently characterized. Fossil polychaetes are briefly mentioned, with specific attention to problems associated with incorporating them in recent systematics.The traditional separation in 'errant' and 'sedentary' polychaetes has increasingly become recognized as being unsatisfactory; however, the current trend towards grouping the polychaetes in many orders without specifying the relationships among the orders, is no more satisfactory. The lack of consistent morphological information is a major source of uncertainty. Intensive morphological studies should remove terminological ambiguities and alleviate some of the problems.

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“…In vestimentiferans and frenulates, bacterial endosymbionts are harbored in the trophosome [8][9][10]38,39) , and not found in germ cells 6,8,13,19) . There are several reports that a mouth and a gut are transiently formed in vestimentiferan larvae 20,40) and in frenulate larvae 4) . It has been thought that the free-living bacteria are taken in through the transiently formed mouth that appears only during a specific larval stage 4,8,20,40) .…”

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confidence: 99%

“…There are several reports that a mouth and a gut are transiently formed in vestimentiferan larvae 20,40) and in frenulate larvae 4) . It has been thought that the free-living bacteria are taken in through the transiently formed mouth that appears only during a specific larval stage 4,8,20,40) . Recently, Nussbaumer et al 30) reported that, in some species of vestimentiferans, free-living bacteria invade through the host's skin to become the endosymbionts.…”

mentioning

confidence: 99%

“…When 65 worms were investigated, 26 individuals (40.0%) were found to have kept endosymbiont A; 10 individuals (15.4%), endosymbiont E; 9 individuals (13.8%), endosymbiont D; and 7 individuals (10.7%), endosymbiont G. The phylogenetic analysis of the 16S rRNA gene of the endosymbionts revealed that they are closely related to each other within the Gammaproteobacteria clade 22,25) . It is generally accepted that siboglinid polychaetes such as O. mashikoi take in the free-living cells of their endosymbionts from the environment in each generation 4,8,30) . However, it is difficult to confirm that the free-living bacterium detected by quantitative PCR targeting the 16S rRNA gene is exactly the same bacterium as endosymbiont A.…”

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confidence: 99%

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Distribution and Population of Free-Living Cells Related to Endosymbiont A Harbored in Oligobrachia mashikoi (a Siboglinid Polychaete) Inhabiting Tsukumo Bay

et al. 2008

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Beard worms (Siboglinidae, Polychaeta), which lack a mouth and a digestive tract, harbor thioautotrophic or methanotrophic bacteria in special cells called bacteriocytes. These endosymbionts have been considered to be trapped at a specific larval stage from the environment. Although many species of beard worms have been discovered in various abyssal seas, Oligobrachia mashikoi inhabits Tsukumo Bay which is only 25 m deep. At least seven types of endosymbionts (endosymbiont A-G) have been distinguished in O. mashikoi. In this study, we investigated the distribution pattern of free-living cells related to the major endosymbiont (endosymbiont A) in Tsukumo Bay by quantitative PCR targeting the 16S rRNA gene. The endosymbiont A-related phylotype was detected in almost all sediment samples collected from 23 points in Tsukumo Bay, ranging in copy number of the 16S rRNA gene from 2.22×10 4 to 1.42×10 6 copies per gram of dry-sediment. Furthermore, the free-living cells made up less than 9% of the total eubacterial population, suggesting that the O. mashikoi larvae precisely select candidates for their endosymbiont from bacterial flora in the environment. This is the first report on the ecological characterization of a free-living bacterium related to the endosymbiont of the siboglinid polychaete, O. mashikoi.

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Larval development and the formation of the gut ofSiboglinum poseidoniFlügel & Langhof (Pogonophora, Perviata). Evidence of protostomian affinity

Cited by 32 publications

References 19 publications

Cladistics and polychaetes

Cladistics and polychaetes

Polychaete systematics: Past and present

Distribution and Population of Free-Living Cells Related to Endosymbiont A Harbored in Oligobrachia mashikoi (a Siboglinid Polychaete) Inhabiting Tsukumo Bay

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