2. Behavioral Biology TALKS - Deutsche Zoologische Gesellschaft

����198 Thomas Stach
Evolution and development of the coronal organ in tunicates: homology to
vertebrate lateral line?
Authors: T. Stach 3 , F. Rigon 1 , S.M. Shimeld 2 , F. Caicci 1 , F. Gasparini 1 , P. Burighel 1 , G.
Zaniolo 1 , L. Manni 1
Affiliations: 1 Department of Biology, University of Padua, Italy; 2 Department of
Zoology, University of Oxford, UK; 3 Institut für Biologie, AG Vergleichende
Zoologie, Humboldt-Universität zu Berlin
The coronal organ is a sensory system present in the oral region of tunicates,
possessing secondary sensory cells supposed to have the same evolutionary origin as
vertebrate hair cells. Indeed, coronal sensory cells strictly resemble the latter,
because of morphology, location, function and embryonic origin. Vertebrate hair cells
are characteristic of the lateral line and inner ear, where they function as
mechanoreceptors. We conducted a comparative ultrastructural analysis of the
coronal organs in several tunicate species and complimented the study with an
examination of molecular developmental aspects in the ascidian Ciona intestinalis.
We found that several genes that are involved in mechanoreceptor differentiation in
vertebrates are expressed around the rudiment of the oral siphon in tadpole larvae of
C. intestinalis. These findings are in agreement with the hypothesis that the coronal
organ in the tunicate C. intestinalis might be homologous to the lateral line system in
vertebrates.
����199 Andrea Weis
DNA barcoding of Sea spiders (Pycnogonida) from the chilean fjord region, with
remarks on Achelia assimilis (Haswell, 1885)
Authors: Andrea Weis 1 , Roland Melzer 1
Affiliation: 1 Staatssammlung München
In the present study we report the first attempt to resolve Chilean pycnogonid
taxonomy using DNA sequence data in combination with morphology. In a subproject
of the Marine Barcode of Life (MarBoL) campaign we analyzed a fragment of the
mitochondrial protein-coding gene COI (cytochrome c oxidase subunit 1) from 76
Chilean/Subantarctic pycnogonids based on about 657 base pairs. Since most
molecular data on pycnogonids are from the Antarctic area, the new information
constitutes a significant extension.
The phylogenetic consensus tree displays 10 distinct, well supported clades
corresponding to the studied species, namely Achelia assimilis (Haswell, 1884),
Ammothea spinosa (Hodgson, 1907), Tanystylum cavidorsum Stock, 1957, T.
neorhetum Marcus, 1940, Colossendeis macerrima Wilson, 1881, C. megalonyx Hoek,
1881, C. scoresbii Gordon, 1932, Callipallene margarita (Gordon, 1932), Pallenopsis
patagonica (Hoek, 1881), and Anoplodactylus californicus Hall, 1912. These represent
four superfamilies, and five of the eleven existing pycnogonid families (Bamber & El
Nagar 2011): Ammotheidae Dohrn, 1881, Colossendeidae Hoek, 1881, Callipallenidae
Hilton, 1942, Pallenopsidae Fry, 1978, and Phoxichilidiidae Sars, 1891.
Within Achelia assimilis, four distinct subclades correspond to the different
geographic regions represented in our samples. While these include a total of 11
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