Above: A white with orange and dark splotches morph.
Below: An impossible sight-except at St. Paul’s Rocks, were these two color variants of H. ciliaris are encountered.
islands in the South Atlantic (Lubbock 1980; Gasparini & Floeter 2001). St. Paul’s Rocks are the farthest location inhabited by H. ciliaris in the South Atlantic, and it probably reaches the Rocks utilizing Atol das Rocas and/or Fernando de Noronha Archipelago as stepping-stones
for colonization. The icthyofauna of these islands are, in fact, considered very similar in a recent biogeographic analysis (Floeter & Gasparini 2000). Despite its relative proximity, the very low density of H. ciliaris in the Fernando de Noronha Archipelago (SR Floeter pers.
obs.) should contribute to the isolation of St. Paul’s population by providing a very little output of recruits (and consequently low genetic flow). The St. Paul’s population of H.ciliaris are thus probably maintaining themselves mainly by self-recruitment (Swearer et al. 1999; Jones et al. 1999; Robertson 2001).
A PLEA FOR CONSERVATION
It is clear that marine species are not exempt from human impacts and extinction risk (Roberts & Hawkins 1999; Hawkins et al. 2000). Our observations show that this population of H. ciliaris posses some risk characteristics:
(1) Restrict geographic range. As defined by Robertson (2001), genetically distinct isolated populations, as in this case, should be treated as endemic species. The only putative case of extinction registered for a reef fish was an island-endemic species (Roberts & Hawkins 1999).
(2) Importance in the aquarium trade. The isolation of St. Paul’s Rocks is not an obstacle