A New Camallanid Nematode from Hawaii 
Elmer R, Noble 1 
ABSTRACT: S piro camallanus istiblenni n. sp. is described from the intestine of 
lstiblennius zebra, a tidepool fish at Oahu, Hawaii. Female worms average 21.5 
mm long, and the adult female:male length ratio is 1.44:1.0. The chief diagnostic 
characters include a reduced posterior ovary, a male caudal papillae pattern of six 
preanal and three postanal, a spicule length ratio of 3:2, and an H -shaped arrange- 
ment of the anterior excretory canal system. The buccal capsule possesses 13-14 
spiral thickenings. The possible evolutionary significance of the posterior ovary is 
mentioned; a list of other parasites of this host and ecological considerations are 
included. 
During the months from November 1962 
to April 1963 I collected tidepool fishes at 
several points around the island of Oahu, Ha- 
waii and examined them for protozoan, hel- 
minth, and arthropod parasites. Among the 
fishes were 50 specimens of lstiblennius zebra, 
half of which contained, in their intestines, nem- 
atodes belonging to the genus Spirocamallanus. 
A detailed study of this worm shows it to be a 
new species, and requires a modification of 
presently accepted diagnostic characteristics of 
the genus and of the family Camallanidae. 
THE HOST AND ITS ENVIRONMENT 
lstiblennius zebra, family Blenniidae, lives 
as an adult among rocks along the shore and 
is often abundant in small tidepools. Tempera- 
ture changes in the water of these pools varied 
(during the days that I was there) between 
22.6 C to 34.8 C, and salinity changes varied 
between 33.68% 0 to 36.20% o . Eggs of the 
fish are deposited in the pools, and larvae 
migrate to open water off shore. Young fish 
return to the rocky shores where they spend 
the remainder of their lives. Adult fish feed 
primarily on a precipitated organic detritus 
called "leptopel” which appears to be chiefly of 
1 Department of Biology, University of California, 
Santa Barbara. This investigation was aided by a grant 
from the National Science Foundation. Facilities were 
provided by the Bureau of Commercial Fisheries, 
Honolulu, and technical assistance was given by Mr. 
Edward Mercer. Manuscript received February 20, 
1965 . 
algal origin. Snails, green algae, and ostracods 
were occasionally found in the stomach. Other 
organisms in the pools were plankton (cope- 
pods, ostracods, crustacean larvae, juvenile 
snails, nematodes, unicellular algae, filamentous 
algae, diatoms), fish ( Bathygobius juscus, 
Abudefduf sordidus, other small fish), sea 
urchins, sea anemones, shrimps, colonial as- 
cidians, small nudibranchs in clumps of algae, 
annelids, snails ( Littorina picta, L. pintado, 
Nerita neglecta, Morula nudus, Cerithium sp., 
and others), and algae ( Lyngbya majuscula, 
Valonia aegagropila, and other species). When 
the host fish were found on coral reefs they 
were associated with the multitudinous fishes 
and other organisms common to the reefs. 
THE PARASITE 
Spirocamallanus istiblenni n. sp. 
(Figs. 1-10) 
host: lstiblennius zebra (Vailland & Sauv- 
age). 
site of infection: Intestine (of 25 out of 
50 hosts). 
location: Marine tidepools at Oahu, Ha- 
waii. 
SYNTYPES : U. S. Nat. Hist. Mus. Helm. Coll. 
Nos. 32914 (male), 32915 (female). 
description : A tabulation of measurements, 
based on nine females and five males, is given 
in Table 1. 
The chief features that distinguish Spiroca- 
mallanus istiblenni from other described species 
are the presence of a posterior ovary, the caudal 
360 
