Morphological deformation in preserved specimens of the deep-sea octopus Graneledone

Although morphology of firm-bodied shallow-water octopuses resists preserva tion-linked deformation, preservation and handling of deep-sea specimens of Glaneledone are hypothesized to deform specimens by accelerating fluid los s from mantle and arm tissues. Principal components analysis finds that sev en of 39 North Pacific specimens of the genus are exceptionally narrow; the remaining specimens show considerable morphological variation, independent of time in preservation. Five exceptionally narrow specimens, including so me paratypes of G. parifica, were collected and preserved by the same trawl ing study; a single unrecorded factor in their common preservation history may have caused their deformation. The high morphological variation among t he remaining specimens, seemingly unique among octopodids, may reflect fact ors as subtle as how the specimen was stored in the jar. Two types of chang e with time in preservation are documented. The mantle wall of formalin-fix ed specimens thins unpredictably after storage for 30 months in 70% ethanol , consistent with deformation in preservation. Skin tubercles on the dorsal mantle, important taxonomic characters, become more prominent during the f irst decade in preservation. To maximize the information specimens with flu id-rich tissues convey and to identify the sources of deformation, the full preservation history and measurements made prior to dissection should be p ermanently recorded.