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On the shape of foregut lumen in sea spiders (Arthropoda: Pycnogonida)

Published online by Cambridge University Press:  21 November 2002

Katsumi Miyazaki
Affiliation:
Seto Marine Biological Laboratory, Kyoto University, 459 Shirahama, Wakayama 649-2211, Japan, E-mail: miyazaki@seto.kyoto-u.ac.jp

Abstract

The shape of foregut lumen in both the pharyngeal and the oesophageal regions has been examined from serial histological sections in 16 species of pycnogonids covering all extant families. Each species has a Y-shaped foregut lumen in transverse section. This result shows that some previous authors misoriented the lumen as inverted Y-shaped. The triradiate Y-shaped foregut lumen has been found among ecdysozoans including tardigrades, onychophorans and scatteringly arthropods. At present, it is not clear whether the Y-shaped state of the characteristic in pycnogonids is convergent or symplesiomorphy with that in tardigrades and onychophorans.

Type
Short Communication
Copyright
© 2002 Marine Biological Association of the United Kingdom

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