Ultrastructure of the introvert and associated structures of the larvae of Halicryptus spinulosus (Priapulida)

Lemburg, Christian

doi:10.1007/bf00397931

Cited by 52 publications

(63 citation statements)

References 22 publications

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“…Nonetheless, there seems to be a general consensus which awaits further conformation. The Priapulida/Kinorhyncha/Loricifera clade should be referred to as Scalidophora (Lemburg 1995, Schmidt-Rhaesa 1996, Ehlers et al 1996. Nielsen (2001) has used the name Cephalorhyncha for this clade, but previous usage of this term included the Nematomorpha (Malakhov 1980).…”

Section: Scalidophora and Nematoidamentioning

confidence: 99%

The New View of Animal Phylogeny

Halanych

2004

Annu. Rev. Ecol. Evol. Syst.

427

260

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■ Abstract Molecular tools have profoundly rearranged our understanding of metazoan phylogeny. Initially based on the nuclear small ribosomal subunit (SSU or 18S) gene, recent hypotheses have been corroborated by several sources of data (including the nuclear large ribosomal subunit, Hox genes, mitochondrial gene order, concatenated mitochondrial genes, and the myosin II heavy chain gene). Herein, the evidence supporting our current understanding is discussed on a clade by clade basis. Bilaterian animals consist of three clades: Deuterostomia, Lophotrochozoa, and Ecdysozoa. Each clade is supported by molecular and morphological data. Deuterostomia is smaller than traditionally recognized, consisting of hemichordates, echinoderms, chordates, and Xenoturbella (an enigmatic worm-like animal). Lophotrochozoa groups animals with a lophophore feeding apparatus (Brachiopoda, Bryozoa, and Phoronida) and trochophore larvae (e.g., annelids and mollusk), as well as several other recognized phyla (e.g., platyhelminthes, sipunculans, nemerteans). Ecdysozoa comprises molting animals (e.g., arthropods, nematodes, tardigrades, priapulids), grouping together two major model organisms (Drosophila and Caenorhabditis) in the same lineage. Platyhelminthes do not appear to be monophyletic, with Acoelomorpha holding a basal position in Bilateria. Before the emergence of bilateral animals, sponges, ctenophorans, cnidarians, and placozoans split from the main animal lineage, but order of divergence is less than certain. Many questions persist concerning relationships within Ecdysozoa and Lophotrochozoa, poriferan monophyly, and the placement of many less-studied taxa (e.g., kinorhynchs, gastrotrichs, gnathostomulids, and entoprocts).

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Section: Scalidophora and Nematoidamentioning

confidence: 99%

The New View of Animal Phylogeny

Halanych

2004

Annu. Rev. Ecol. Evol. Syst.

427

260

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“…As a consequence, the cuticle is described as consisting of two layers only (see Moritz 1972;Saldarriaga et al 1995;Storch 1984Storch , 1991, and, therefore, does not correspond with the herein given description of three main layers. The presence of exocuticle II has been mentioned already by Lemburg (1995a). In this article, it was assigned to the endocuticular layers based on its fibrillar appearance.…”

Section: Discussionmentioning

confidence: 84%

“…Therefore, these layers can be postulated for the ground pattern of the Priapulida (see Lemburg 1995a). Moreover, some electron-dense material which is not completely fused with the overlying exocuticle I can be seen in the endocuticle of e.g.…”

Section: Discussionmentioning

confidence: 98%

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Electron microscopical localization of chitin in the cuticle of Halicryptus spinulosus and Priapulus caudatus (Priapulida) using gold-labelled wheat germ agglutinin: phylogenetic implications for the evolution of the cuticle within the Nemathelminthes

Lemburg

1998

Zoomorphology

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“…A definition of the Tubiluchidae given by Adrianov et al [27] contains additional items: meiobenthic worms; introvert and trunk separated by distinct neck area; neck folded or with soft cuticular plates; trunk densely covered with tumuli, without annuli; tail monocaudal, long, smooth and slender, introvert bearing 25 rows of scalids. The last item has also been supported by other works [28,29]. It should be pointed out that features including "meiobenthic worms" and "polythyridium" are shared by Meiopriapu!us, which is devoid of any caudal appendage and was assigned to the Tubiluchidae [ 30].…”

Section: (D) 2(i) and 20)mentioning

confidence: 98%

The earliest-known ancestors of Recent Priapulomorpha from the Early Cambrian Chengjiang Lagerst�tte

Han¹

2004

Chinese Sci Bull

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The taxonomy of an early ancestor of Recent Priapulidae, Xiaoheiqingella peculiaris (= Yunnanpriapulus halteroformis Huang et aI., 2004) from the Early Cambrian Chengjiang fossil Lagerstatte, is revised. Morphological characters comprise a pair of caudal appendages rather than a single appendage flanking the trunk end and a possible urogenital duct found inside the preanal region. An additional extremely rare fossil priapulid worm, Paratubiluchus bicaudatus gen. nov., sp. nov. is also described herein. Its diagnostic characters are: an introvert bearing 25 longitudinal rows of scalids, a distinct neck region, no annulus on the oval trunk, and a pair of caudal appendages. The proportion of body parts is similar in size to that of loricate larvae of Recent priapulids and larva-formed Palaeopriapulitidae. Taking account of the features of Xiaoheiqingella, bicaudal appendages are considered to be a synapomorphy of Priapulidae and Tubiluchidae. Paratubiluchus gen. nov. is most likely a candidate for the ancestor of the Tubiluchidae; it probably originated from a larva-formed priapulid with 25 rows of scalids, thus representing an intermediate link between the priapulids in mature-form and the priapulids with lorica.

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Ultrastructure of the introvert and associated structures of the larvae of Halicryptus spinulosus (Priapulida)

Cited by 52 publications

References 22 publications

The New View of Animal Phylogeny

The New View of Animal Phylogeny

Electron microscopical localization of chitin in the cuticle of Halicryptus spinulosus and Priapulus caudatus (Priapulida) using gold-labelled wheat germ agglutinin: phylogenetic implications for the evolution of the cuticle within the Nemathelminthes

The earliest-known ancestors of Recent Priapulomorpha from the Early Cambrian Chengjiang Lagerst�tte

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