IMIS | Flanders Marine Institute

Flanders Marine Institute

Platform for marine research


Publications | Institutes | Persons | Datasets | Projects | Maps
[ report an error in this record ]basket (0): add | show Printer-friendly version

18S rRNA phylogeny of sea spiders with emphasis on the position of Rhynchothoracidae
Nakamura, K.; Kano, Y.; Suzuki, N.; Namatame, T.; Kosaku, A. (2007). 18S rRNA phylogeny of sea spiders with emphasis on the position of Rhynchothoracidae. Mar. Biol. (Berl.) 153(2): 213-223.
In: Marine Biology. Springer: Heidelberg; Berlin. ISSN 0025-3162, more
Peer reviewed article  

Available in  Authors 


Authors  Top 
  • Nakamura, K.
  • Kano, Y.
  • Suzuki, N.
  • Namatame, T.
  • Kosaku, A.

    The phylogenetic relationships among all living families of sea spiders (Arthropoda: Pycnogonida) are investigated using nearly complete 18S rRNA sequences from 57 ingroup species and five chelicerates under the Bayesian and maximum likelihood methods. Monophyly of Colossendeidae, Pycnogonidae, Phoxichilidiidae, Endeidae and Pallenopsidae is consistently supported. However, the genera formerly classified in the family Ammotheidae are split up into two distantly related groups. The genera Ascorhynchus and Eurycyde (here recognized as Ascorhynchidae) are possibly an early offshoot of sea spiders, whereas other ammotheids constitute a robust terminal clade with Pallenopsidae, Phoxichilidiidae and Endeidae. This topology also opposes the prevalent assumption of successive losses and simplification of three kinds of cephalic appendages like in a previous cladistic analysis. At least three independent losses are suggested for palps by the inferred topology, and both chelifores and female ovigers may have been lost twice. Our knowledge of early ontogeny and internal anatomy is more congruent with the present 18S rRNA data. The families Callipallenidae and Nymphonidae with unique “attaching larvae” are grouped together in present molecular trees, suggesting that extended paternal care of offspring evolved only once in Pycnogonida. Confident clustering of Pycnogonidae and Rhynchothoracidae indicates that the number of female genital pores is an evolutionary conservative character.

All data in IMIS is subject to the VLIZ privacy policy Top | Authors