The Echinoidea Collected by the Royal Society of 
London Expedition to Southern Chile, 1958-1959 
David L. Pawson 1 
ABSTRACT : The collection comprises the species Arhacia dufresnei ( Blainville ) , 
Pseudechinus magellanicus (Philippi), and Loxechinus albus (Molina). Typical 
temnopleurid epistroma is now known to be present in juveniles of Pseudechinus 
magellanicus , and the disposition of the ocular plates in the apical system in this 
species is determined by the position of the anal aperture. The shallow water 
echinoid fauna of southern Chile includes the endemic genera Loxechinus and 
Tetrapygus, and genera with antarctic ( Tripylus ) and circumpolar ( Pseudechinus ) 
affinities. 
During late 1958 and early 1959, an expedi- 
tion sponsored by the Royal Society of London 
conducted marine and terrestrial investigations 
in southern Chile. Littoral marine stations were 
established in three separate areas: (1) Isla 
Chiloe (approx. 42 °S), (2) Puerto Eden to 
Punta Arenas (approx. 49°-52°S), and (3) 
Isla Navarino and southern regions (approx. 
55°S). 
The present paper contains an account of the 
Echinoidea collected in the intertidal and sub- 
littoral zones by the expedition’s marine biolo- 
gist, Professor G. A. Knox, of Canterbury Uni- 
versity, Christchurch, N.Z. 
The collection contains 243 specimens which 
represent three genera and three species. The 
three species are common in southern Chile and 
are typical of that area. Pseudechinus magel- 
lanicus (Philippi) is abundant in the collec- 
tion. It is a species of a southern genus which 
apparently originated in Australasia, and has 
spread to various subantarctic localities with the 
aid of the west wind drift. Loxechinus alhus 
(Molina) is a large urchin with a green test and 
green spines and is used extensively as food in 
the areas in which it occurs. The third species, 
Arbacia dufresnei (Blainville), has a charac- 
teristic green test and purple spines. 
I would like to thank Professor G. A. Knox 
1 U. S. National Museum, Smithsonian Institution, 
Washington 25, D.C. Manuscript received November 
17, 1964. 
and the Royal Society for the opportunity to 
study this collection. 
MATERIAL EXAMINED 
Echinoids were collected at the following 
stations: 
Stn. 19. Puerto Eden, Isla Wellington, 49° 08' 
2Q"S, 74°26'55"W; intertidal granitic gneiss 
rocks, sheltered; hand collecting, also collec- 
tion from Macrocystis fronds and holdfasts, 
and sublittoral collection by diving; Nov. 29- 
30, 1958. Pseudechinus magellanicus, 8 speci- 
mens. 
Stn. 21. Puerto Eden, 49°08'30"S, 74°26'52" 
W; depth 16-18 m, grey sand; dredge; Dec. 
2, 1958. P. magellanicus, 5 specimens. 
Stn. 22. Puerto Eden, 49°08'48"S, 74°26'48" 
W; depth 6-8 m, grey sand with small stones; 
dredge; Dec. 2, 1958. Arbacia dufresnei, 1 
specimen; P. magellanicus, 8 specimens. 
Stn. 24. Puerto Eden, 49°08'31"S, 74 0 26'48" 
W; depth 10-12 m, grey sand; dredge; Dec. 
4, 1958. P. magellanicus, 2 specimens. 
Stn. 27. Isla Carlos, 49°09'35"S, 74°25'24" W; 
collection from Macrocystis fronds and hold- 
fasts; Dec. 5, 1958. A. dufresnei, 1 specimen. 
Stn. 29. Isla Carlos, Puerto Eden, 49°08'38"S, 
74°25'32"W; intertidal gneiss rocks, semi- 
exposed; hand collecting; Dec. 6, 1958. P. 
magellanicus, 1 specimen. 
