introduction to kinorhyncha and...

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Martin V. Sørensen

Associate Professor and curator of microscopic invertebrates

Natural History Museum of Denmark

Introduction to

Kinorhyncha and Gnathostomulida

Block course on Zoology and Evolution, Biozentrum, Uni. Basel

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Martin V. Sørensen

Associate Professor and curator of microscopic invertebrates

Natural History Museum of Denmark

• Taxonomy, biodiversity, morphology,

and phylogeny

• Kinorhyncha, Priapulida, Loricifera,

Rotifera, Gnathostomulida and

Micrognathozoa

• Metazoan Phylogeny

• Curator of Microscopic Invertebrates

Introduction to

Kinorhyncha and Gnathostomulida

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Edgecombe et al. (2011) Higher-level metazoan relationships: Recent progress and remaining questions. Org. Div. Evol.

Ecdysozoa

Platyzoa

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Platyzoa and Gnathostomulida

Platyhelminthes Gastrotricha Gnathostomulida

Rotifera (Monogononta – Acanthocephala -

Bdelloidea - Seisonidea)

Gnathifera

Micrognathozoa

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Gnathostomulida: Jaw Worms

• Marine, interstitial worms, 100 species

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• Marine, interstitial worms, 100 species

• Ventral mouth leading to blind gut

Gnathostomulida: Jaw Worms

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• Marine, interstitial worms, 100 species

• Ventral mouth leading to blind gut • Simple cephalic sensory organs

• Simple epidermis with monociliated cells

Gnathostomulida: Jaw Worms

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Gnathostomulida: Jaw Worms

• Marine, interstitial worms, 100 species

• Ventral mouth leading to blind gut • Simple cephalic sensory organs

• Simple epidermis with monociliated cells

• Pharynx with hard parts forming jaws

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Gnathostomulida: Jaw Worms

• Marine, interstitial worms, 100 species

• Ventral mouth leading to blind gut • Simple cephalic sensory organs

• Simple epidermis with monociliated cells

• Pharynx with hard parts forming jaws

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Haplognathia lunulifera Gnathostomula paradoxa

Problognathia minima

Mesognatharia remanei

Tenuignathia rikerae

Rastrognathia macrostoma

Gnathostomulida: Jaw Worms

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Two classes: Filospermoidea Bursovaginoidea

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Two classes: Filospermoidea Bursovaginoidea

Reproductive mode: • Hermaphrodite • Soft, muscular penis • Filiform sperm cells Reproductive mode:

• Hermaphrodite • Sclerotized penis stylet and dwarf sperm • Or – non-sclerotized penis with giant sperm cells • Female organs with bursa

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Two classes: Filospermoidea Bursovaginoidea

Order: Scleroperalia

Penis stylet

Testes

Bursa

Ovarium

Spermatozoa

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Gnathostomulida:

Biology and distribution

• Sand mixed with detritus

• Never in mud • Never in clean sand, e.g., high energy

beaches

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Gnathostomulida: Jaw Worms

• Discovered in 1928 by Adolf Remane

• Found again in the 1950’ies and described in 1956 as a turbellarian order (Ax, 1956)

• Raised to class level, but still a Platyhelminthes (Ax, 1964)

• Assigned phylum rank, but with uncertain phylogenetic position (Riedl, 1969)

• Independently, Ahlrichs (1995) and Rieger & Tyler (1995) do comparative studies of gnathostomulids and rotifers

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Gnathostomulida: Jaw Worms

Rotifera Gnathostomulida

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Gnathostomulida: Jaw Worms

Micrognathozoa

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Platyzoa and Gnathostomulida

Platyhelminthes Gastrotricha Gnathostomulida

Rotifera (Monogononta – Acanthocephala -

Bdelloidea - Seisonidea)

Gnathifera

Micrognathozoa

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Kinorhyncha: Mud dragons

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Edgecombe et al. (2011) Higher-level metazoan relationships: Recent progress and remaining questions. Org. Div. Evol.

Ecdysozoa

Platyzoa

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Ecdysozoa

Kinorhyncha (Mud dragons)

Nematoda (Round worms)

Tardigrada (Water bears)

Arthropoda (Arthropods)

Priapulida (Priapulid

worms)

Loricifera (Girdle

wearers)

Nematomorpha (Gordian worms)

Onychophora (Velvet worms)

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Kinorhyncha

• 189 described species

• Marine, meiobenthic

• Present from tidal zone to over 7000 m depth

• Sizes from 130 µm up to 1 mm

• Are composed of a head, a neck and 11 trunk segments

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Kinorhyncha Head

Neck

Trunk

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Kinorhyncha

Mouth cone

Introvert

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Kinorhyncha

Neck

Placids

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Kinorhyncha

Placids

Neck

Placids

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Kinorhyncha

Plate junctions

Segments

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Kinorhyncha

Plate junctions

Segments

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Kinorhyncha

Spines

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Kinorhyncha Development through 6 juvenile stages

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Kinorhyncha: Global Biodiversity

= only few species reported, or kinorhynch fauna known from a single locality only

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Kinorhyncha: Korean Biodiversity Program

• Campyloderes macquariae • Condyloderes megastigma • C. paradoxus • Dracoderes abei • D. orientalis • Dracoderes n. sp. 1 • Echinoderes aspinosus • E. aureus • E. cernunnos • E. koreanus • E. microaperturus • E. obtuspinosus • E. rex • E. tchefouensis • E. ulsanensis • Echinoderes n. sp. 1 • Echinoderes n. sp. 2 • Kinorhynchus yushini • Meristoderes elleae • M. glaber • M. herranzae • M. imugi • Meristoderes n. sp. • Paracentrophyes anurus • Pycnophyes tubuliferus • Pycnophyes n. sp. 1 • Pycnophyes n. sp. 2 • Pycnophyes n. sp. 3 • Pycnophyes n. sp. 4 • Sphenoderes poseidon

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Kinorhyncha: Gulf of Mexico Research Initiative

• Antygomonas n. sp. • Echinoderes n. sp. 1 to 11 • Echinoderes spinifurca • Paracentrophyes n. sp. • Pycnophyes n. sp. • Sphenoderes n. sp.

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Ecdysozoa

Kinorhyncha (Mud dragons)

Nematoda (Round worms)

Tardigrada (Water bears)

Arthropoda (Arthropods)

Priapulida (Priapulid

worms)

Loricifera (Girdle

wearers)

Nematomorpha (Gordian worms)

Onychophora (Velvet worms)

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Ecdysozoa

Kinorhyncha Nematoda Tardigrada Arthropoda Priapulida Loricifera Nematomorpha Onychophora

Ecdysozoa

• Cuticle formed from microvilli tips • Molting • Ecdysone • Loss of locomotory cilia

Scalidophora Nematoida

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Ecdysozoa

Kinorhyncha Nematoda Tardigrada Arthropoda Priapulida Loricifera Nematomorpha Onychophora

Panarthropoda

Segmentation of trunk and limbs

Cycloneuralia

Ring-shaped brain around pharynx

Scalidophora Nematoida

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Cycloneuralia:

Scalidophora and Nematoida

Kinorhyncha Nematoda Priapulida Loricifera Nematomorpha

Scalidophora Nematoida

• Introvert + mouth cone • Scalids • Papillar sense organs (flosculi) • Protonephridia

• Unpaired dorsal and ventral nerve strings • Loss of circular muscles • Loss of sperm flagellum • Both sexes with cloaca • Vermiform habitus

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Molecular data does not support

Scalidophora

Kinorhyncha Nematoda Priapulida Loricifera Nematomorpha

Scalidophora Nematoida

Plesiomorphies? Adult morphology

18S rRNA

• Introvert + mouth cone • Scalids • Papillar sense organs (flosculi) • Protonephridia

• Unpaired dorsal and ventral nerve strings • Loss of circular muscles • Loss of sperm flagellum • Both sexes with cloaca • Vermiform habitus

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Loriciferan – Nematomorph sister groups? Loricifera Nematomorpha

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Loricifera Nematomorpha

• Hexaradial symmetry patterns in pharynx, opposed to pentaradial symmetry patterns in Kinorhyncha and Priapulida

Loriciferan – Nematomorph sister groups?

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Loricifera Nematomorpha

?

Evolution through Progenesis?

Progenesis: Evolution through sexual maturation of larval stage, which causes the loss of following preadult and adults stages

Loriciferan – Nematomorph sister groups?

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Evolution through Progenese

Loss of larva

Original cycle maintained

Loss of adult stage through progenesis

Loriciferan – Nematomorph sister groups?

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The New Ecdysozoan Phylogeny?

Kinorhyncha (Mud dragons)

Nematoda (Round worms)

Tardigrada (Water bears)

Arthropoda (Arthropods)

Priapulida (Priapulid

worms)

Loricifera (Girdle

wearers)

Nematomorpha (Gordian worms)

Onychophora (Velvet worms)

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