Material and methods
Most of the type material was collected using ROV manipulators and is preserved in 75% ethanol. One specimen (CAS 175885) was originally fixed in 10% seawater formalin and later transferred to 75% ethanol. In addition to the specimens collected by ROVs, approximately twelve specimens representing one lot were recently found in the invertebrate zoology collection of California Academy of Sciences (CAS). These specimens were collected by benthic trawl off the Oregon coast in 1973 and were preserved in 75% ethanol. We have found this material to be conspecific with the new taxon. Microscopes used in this study include a Nikon SMZ-10 dissecting microscope, an Olympus CH-2 compound microscope, and a Leo 1400 series scanning electron microscope.
In situ observations of living colonies were made using high-resolution video (Ikegami HDL-40 and Panasonic WV-E550) and digital still (Nikon Cooplpix 990) cameras (figs. 2, 3). Over 250 hours of video recordings from San Juan, Rodriguez, Davidson and Pioneer Seamounts, Monterey Canyon, and the continental slope off northern California were reviewed using MBARI’s Video Annotation Reference System, VARS (Schlining & Jacobsen Stout, 2006). Living Gersemia colonies and associated habitats were identified in video and added to the searchable VARS database. Within VARS, these video observations were merged with ancillary data (latitude, longitude, depth, temperature, and oxygen concentration) that were collected by the ROV at the time of deployment. The VARS query was used to export video observation data for analysis and the data were mapped using ArcGIS 9.3. In addition, six video transects were collected to estimate organism density (Monterey Canyon n=5; Pioneer Seamount n=1). Two parallel red lasers (640 nm) positioned 29 cm apart were used to estimate transect width. Transect length was calculated in ArcView® 3.2 using the Animal Movement Analysis Extension, Version 2, which was used to calculate successive distance between the start and end points of each transect (Hooge & Eichenlaub, 1997).