Illustrated Key to the Shallow-Water Gorgonians and 
Pennatulaceans of the Verde Island Passage, Northern 
Philippines, Including Synopses of the Taxa and a 
Glossary of Terms (Cnidaria: Anthozoa: Octocorallia) 
Gary C. Williams and Jei-Ying Chen 
Department of Invertebrate Zoology and Geology, California Academy of Sciences, 
55 Music Concourse Drive, San Francisco, California 94118 USA 
Email: gwilliams@calacademy.org; cchen@calacademy. oig 
A guide is here presented to twenty-six genera of gorgonian and pennatulacean octo- 
corals that are commonly seen by divers on the coral reefs of the Verde Island Pas¬ 
sage region of the northern Philippines, between southern Luzon and northern Min¬ 
doro. Ten of these are identified to species level. Each taxon is illustrated with color 
photographs either in situ or of presen ed specimens, as well as with scanning elec¬ 
tron micrographs or drawings of sclerites that are crucial for identification purpos¬ 
es. All material used in the study was collected during eighteen years of field work 
by Academy scientists, including the Hearst Biodiversity Expedition of 2011, and is 
housed in the marine invertebrate collections of the California Academy of Sciences. 
A glossary of technical terms used in the key is appended to the end of the main body 
of text. 
Keywords; Illustrated Key, Gorgonians, Pennatulaceans, Sea Fans, Sea Whips, Sea Pens, 
Shallow Water, Verde Island Passage, Philippines, Glossary of Terms 
Between 1993 and 2012, field researchers from the California Academy of Sciences made 
extensive collections of octocorallian cnidarians (soft corals, gorgonians, and sea pens) that are fre¬ 
quently encountered from the shallow water (0-40 meters in depth) coral reefs and adjacent habi¬ 
tats of the Philippine archipelago. 
This paper provides an illustrated identification key to common taxa of the gorgonian and pen¬ 
natulacean faunas that are known to inhabit the coral reef region between southern Luzon and 
northern Mindoro — the area known as the Verde Island Passage, which comprises an oceanic link 
between The South China Sea on the east, the Sibuyan Sea in the central Philippmes, and the 
Philippine Sea to the west. Such updated identification guides have proved valuable as guides to 
local or global faunal composition and biodiversity assessments, as shown by the examples of such 
guides to soft corals and sea fans (Fabricius and Alders lade 2001), sea pens (Williams 1995), and 
azooxanthellate hard corals (Cairns and Kitahara 2012). 
Biogeographic Setting. — The Philippine archipelago comprises over 7100 islands (Dr. 
Cathy Lagunzad, Ateneo de Manila University and University of the Philippines, pers. comm.) and 
occupies the northern part of the Coral Triangle in the tropical western Pacific Ocean, between 
approximately 5 and 20 degrees north latitude (Fig. 1 A). 
The Coral Triangle is the region of the tropical western Pacific Ocean that has been recognized 
as having the world’s highest shallow-water marine species diversity with regard to scleractinian 
corals (Hoeksema 2007; Veron et al. 2009), and similarly for fishes (Carpenter and Springer 2005; 
Gaither and Rocha 2013). 
This region as here recognized includes eastern Indonesia, The Philippines, northern New 
Guinea, the Bismarck Archipelago, and the Solomon Islands (Fig. 2A). 
67 
