A New Species of Pachycerianthus , with a Discussion of the 
Genus and an Appended Glossary 1 
Mary Needler Arai 2 
ABSTRACT: A new species of Pachycerianthus from southern California is de- 
scribed and the status of the genus is discussed. A glossary of the terms used in 
the taxonomy of the order is appended. 
The order Ceriantharia consists of long, soli- 
tary, anemone-like Anthozoa, without a pedal 
disc or external skeleton, with numerous single 
tentacles in two crowns, coupled mesenteries, 
and a single siphonoglyph. Earlier authors re- 
lated these anemones to the Actiniaria, but they 
are recognized by recent authors, such as Wells 
and Hill (1956), as being most closely related 
to the Antipatharia or "black corals.” 
Previous knowledge of the taxonomy and mor- 
phology of the Californian Ceriantharia is mea- 
gre. McMurrich (1893:202-203) described a 
species, Cerianthus vas, from one poorly pre- 
served specimen that had been collected at Isla 
de Cedros, Baja California, Mexico. The where- 
abouts of this specimen is unknown and the 
information given is insufficient to allow iden- 
tification of the species or to place it in any 
recent genus or family. Torrey and Kleeberger 
(1909) described three species: Cerianthus 
aestuari, C. benedeni, and C. johnsoni, basing 
their descriptions on animals collected from 
Mission Bay, San Diego Bay, and San Pedro 
Harbor, California, respectively. The descrip- 
tion of the latter species was based on two 
specimens. Although these descriptions were 
incomplete, enough morphological data were 
given so that McMurrich (1910:11) placed 
Cerianthus benedeni in the genus Botruanthus, 
which he erected for it. He placed the other 
two species in the genus Pachycerianthus 
Roule. Carlgren (1951:433-436) described 
Pachycerianthus insignis from a single incom- 
1 Much of the data presented in this paper was in- 
cluded in a dissertation submitted to the University of 
California, Los Angeles, in partial fulfillment of the 
requirements for the Ph.D. degree. Manuscript re- 
ceived February 3, 1964. 
2 Former address : Department of Zoology, Univer- 
sity of California, Los Angeles, California. Present ad- 
dress: Department of Biology, University of Alberta, 
Calgary, Alberta. 
plete specimen, and redescribed Botruanthus 
benedeni from four specimens, all taken from 
the Gulf of California. 
Child (1908) reported on regeneration in 
Pachycerianthus aestuari. Other authors have 
referred to forms collected in California, but 
have not identified them. When specimens 
were obtained by divers near Los Angeles it 
was found that they belonged to previously 
undescribed species. One of these species is 
described here with a discussion of the genus 
Pachycerianthus in which it is placed. 
As indicated by Torelli (1960:373), the 
terminology used for the various anatomical 
structures in the Ceriantharia is greatly con- 
fused in the literature. A glossary of terms 
used in the taxonomy of this group is there- 
fore appended, and the terminology used 
throughout this work has been standardized 
for uniformity. 
MATERIAL AND METHODS 
The sea anemones on which the anatomical 
descriptions are based were collected by Dr. 
Rimond Fay and Mr. Philip Bernard of the 
Pacific Bio-marine Supply Company between 
July, 1958 and August, I960 and were main- 
tained in the sea water tanks of the Depart- 
ment of Zoology, University of California at 
Los Angeles. On removal from the tanks, the 
animals were anaesthetized for 2-8 hours in 
equal parts of sea water and a solution of 
0.36M MgCl2.6H 2 0. They were fixed for ap- 
proximately 15 minutes in 10% neutral forma- 
lin (with an excess of MgCOs), overnight in 
picro-formol solution (one part concentrated 
formalin: 3 parts saturated picric acid), and 
stored in 70% ethanol. In each case the solu- 
tions were pipetted into the coelenteron. 
Preliminary identification of nematocyst types 
was done on fresh material. The nematocyst 
205 
