Morphology and ultrastructure of the anterior end of Diplocirrus longisetosus Marenzeller, 1890 (Flabelligeridae, Polychaeta, Annelida)

Filippova, Anna V.; Tzetlin, Alexander B.; Purschke, Günter

doi:10.1023/a:1026148900074

Cited by 7 publications

(11 citation statements)

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“…A retractable head (26), where the prostomium, peristomium and, possibly, some anterior segments can be withdrawn into a segmental invagination, is found in a number of polychaetes, and it is seen here in Diplocirrus and Fauveliopsis. We accept the arguments by Filippova et al (2003) that the head of these taxa is only comprised of the prostmium and peristomium. The outgroups showed two states for the basic shape of the first segment (27), dorsally limited (Hesiospina), or similar to those following (Nephtys).…”

Section: Paralvinella Palmiformismentioning

confidence: 70%

“…We also regard the branchiae of flabelligerids as segmental structures that have migrated to be in an anterior position. This is argued in Rouse and Pleijel (2001), though it should be noted that Filippova et al (2003) suggested that the branchiae of Diplocirrus are peristomial, meaning that they are completely new structures. The appearance of branchiae on segments 1-5 is coded as five separate characters, further arguments regarding these features in terbellomorphs can be found in Rousset et al (2003).…”

Section: Paralvinella Palmiformismentioning

confidence: 94%

“…These are characters used by Rousset et al (2003), as is the scoring for terebelliforms, except for Pista, which is based on Kritzler (1984). For most other terminals Rouse and Pleijel (2001) provided justifications, while the scoring for Diplocirrus and Fauveliopsis follows Filippova et al (2003). There is uncertainty as to the position of the initial segments in Magelona, so they are scored with ''?''.…”

Section: Paralvinella Palmiformismentioning

confidence: 99%

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The phylogenetic position of Siboglinidae (Annelida) inferred from 18S rRNA, 28S rRNA and morphological data

et al. 2004

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We assess the phylogenetic position of Siboglinidae (previously known as the phyla Pogonophora and Vestimentifera, but now referred to Annelida) in parsimony analyses of 1100 bp from 18S rRNA, 320 bp from the D1 region of 28S rRNA, and 107 morphological characters, totaling 667 parsimony informative characters. The 34 terminal taxa, apart from six siboglinids, include polychaete members of Sabellida, Terbelliformia, Cirratuliformia and Spionida, plus two Aciculata polychaetes as outgroups. Our results contradict most recent hypotheses in showing a sistergroup relationship between Siboglinidae and Oweniidae, and in that the latter taxon is not a member of Sabellida. Furthermore, our results indicate that Sabellariidae is not closely related to Sabellida, that Serpulidae may be nested within Sabellidae, and that Alvinellidae is nested within Ampharetidae.

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Section: Paralvinella Palmiformismentioning

confidence: 70%

Section: Paralvinella Palmiformismentioning

confidence: 94%

Section: Paralvinella Palmiformismentioning

confidence: 99%

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The phylogenetic position of Siboglinidae (Annelida) inferred from 18S rRNA, 28S rRNA and morphological data

et al. 2004

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“…As in Fauveliopsidae, the brain has a basiepithelial position attached anteriorlateral to the prostomial epidermis. However, there might be some variability in Flabelligeridae; although not studied in detail, Filippova et al (2003) reported the division of the brain into two halves in D. longisetosus , indicating the necessity for broader taxon sampling in the group. The specific structure in the brain outlined here, as well as the prostomial retractor attachment sites between the brain lobes may well be the first clear morphological autapomorphies for Fauveliopsidae.…”

Section: Discussionmentioning

confidence: 95%

“…adriatica (Schlieper 1927). On the other hand, Filippova et al (2003) described separated ganglia and a long connective between the ganglia of the first and the second chaetiger in Diplocirrus longisetosus M arenzeller 1890, indicating some variability among flabelligerid species. Moreover, the number of observed lateral nerves in Flabelligeridae is higher than that in F .…”

Section: Discussionmentioning

confidence: 99%

Sipunculid-like ocellar tubes in a polychaete, Fauveliopsis cf. adriatica (Annelida, Fauveliopsidae): implications for eye evolution

Purschke

2011

Invertebrate Biology

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A retractable head region somewhat resembling the introvert of sipunculans is a characteristic feature of members of the annelid taxon Fauveliopsidae. The morphology of fauvelopsids is not well known, and additional data might help to resolve their relationships with other annelids and sipunculans. Ultrastructural investigations of the anterior end of adults of Fauveliopsis cf. adriatica revealed peculiar brain and sensory structures. From the neuropil of the brain, two pairs of lobes mainly composed of neuronal somata extend posteriorly into the peristomium and the following segment. The nuchal organs are embedded in the median pair of lobes, as are additional photoreceptor-like sensory structures, the ocellar tubes, which are found at the bases of epidermal follicles that extend deeply into the brain. The retractor muscles of the prostomium are attached to the apices of these follicles, which are lined by tendon and supportive cells. The lumen of each follicle is completely filled with cuticular material that forms a rod. Monociliary sensory cells are present all along the length of each follicle; their cilia extend into the cuticle, and are oriented parallel to the longitudinal axis of the tube. Basally, each follicle forms an ovoid extension that is devoid of cuticular material and densely filled with numerous sensory processes-microvilli and ciliaof bipolar sensory cells. The terminal end of the 40-mm-deep follicle is formed by two conspicuous cells that contain numerous densely packed vesicles that resemble pigment granules. The ocellar tubes of fauveliopsids are strikingly similar to the ocular tubes of sipunculids. These similarities may reflect common ancestry or may represent convergent evolution; both alternatives are partially supported by previous morphological and molecular studies.

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Pikaia gracilens Walcott: Stem Chordate, or Already Specialized in the Cambrian?

Mallatt

Holland

2013

J Exp Zool Pt B

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For the past 35 years, the Cambrian fossil Pikaia gracilens was widely interpreted as a typical basal chordate based on short descriptions by Conway Morris. Recently, Conway Morris and Caron (CMC) (2012, Biol Rev 87:480-512) described Pikaia extensively, as a basis for new ideas about deuterostome evolution. This new Pikaia has characters with no clear homologues in other animals, so they could be phylogenetically uninformative autapomorphies. These characters include a dorsal organ, posterior ventral area, posterior fusiform structure, and anterior dorsal unit. Yet CMC interpret most of the unusual characters as primitive for chordates, thereby interpreting Pikaia as an even more convincing stem chordate than before. Moreover, they claim that segment (myomere) shape is a reliable guide for defining a chordate and even for assigning animals to their correct place in deuterostome phylogeny. By defining sigmoidal segments as a basal chordate character, they situate Pikaia at the base of the chordates and banish fossil yunnanozoans (which have straight segments) to a position deep within the deuterostomes. In addition, they consider amphioxus, with its conspicuously chevron-shaped segments, to be so highly derived that it is of little use for reconstructing the first chordates. We question their overemphasis on the phylogenetic value of segment shape and their marginalizing of amphioxus. We deduce that Pikaia, not amphioxus, is specialized. We performed a cladistic analysis that showed the character interpretations of CMC are consistent with their wide-ranging evolutionary scenario, but that these interpretations leave unresolved the position of Pikaia within chordates.

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Morphology and ultrastructure of the anterior end of Diplocirrus longisetosus Marenzeller, 1890 (Flabelligeridae, Polychaeta, Annelida)

Cited by 7 publications

References 0 publications

The phylogenetic position of Siboglinidae (Annelida) inferred from 18S rRNA, 28S rRNA and morphological data

The phylogenetic position of Siboglinidae (Annelida) inferred from 18S rRNA, 28S rRNA and morphological data

Sipunculid-like ocellar tubes in a polychaete, Fauveliopsis cf. adriatica (Annelida, Fauveliopsidae): implications for eye evolution

Pikaia gracilens Walcott: Stem Chordate, or Already Specialized in the Cambrian?

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