Microstructure of octocoral sclerites for diagnosi

Authors: Dafna Aharonovich Yehuda Benayahu

Publish Date: 2011/09/28

Volume: 42, Issue: 2, Pages: 173-177

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Abstract

The octocoral family Xeniidae constitutes a major faunistic component of IndoPacific coral reefs particularly in the Red Sea The sclerites of several common genera among which Xenia are composed of minute platelets or corpusclelike forms with a surface that appears almost smooth at light microscope magnification Scanning electron microscopy SEM revealed the fine microstructure of the xeniidsclerites leading to the establishment of several new taxa including the genus Ovabunda whose spheroid sclerites are composed of aggregations of minute microscleres rather than the Xeniastyle platelets The present study applied for the first time highresolution environmental SEM ESEM in order to examine the detailed structure of these octocoral sclerites It determines whether and how the microstructural features in three type specimens of O biseriata O faraunensis and O impulsatilla play a role in determining their structural stability namely how the corpuscular microscleres adhere together and maintain the sclerites’ spheroid shape The study revealed the surface of the microscleres to be constructed of coarse granular crystals and the adjacent microscleres to be interconnected by various microstructural means It is suggested that these microstructural features are diagnostic for the genus Future examination of type specimens of other Ovabunda species as well as additional xeniid genera will also enable a better evaluation of the taxonomic importance of highresolution images in relation to other generaWe thank AD Chipman the Natural History Collection The Hebrew University of Jerusalem for the loan of type material We acknowledge Y Delaria for SEM work Z Barkay for ESEM work A Shlagman for curatorial skills V Wexsler for digital editing of the sclerite images and N Paz for editorial assistance The study was in part supported by the Israel Cohen Chair in Environmental Zoology to YB and by Grant 2008186 from the United StatesIsrael Binational ScienceFoundation BSF Jerusalem Israel to YB Catherine S McFadden and R Toonen The article constitutes part of an MSc thesis in Ecology and Environmental Quality at TelAviv University submitted by D Aharonovich

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