The Zoeal Stages and Glaucothoe of the Tropical Eastern Pacific Hermit Crab 
Trizopagurns magnificus (Bouvier, 1898) (Decapoda; Diogenidae), 
Reared in the Laboratory 1 
Anthony J. Provenzano, Jr. 
ABSTRACT: Larvae were reared under various temperature conditions. Those 
maintained at 15°C were unable to moult to the second instar although some in- 
dividuals lived as long as 35 days after hatching. At 20°C some individuals were 
able to reach fifth instar, but glaucothoes were obtained only at 25 °C, 33-52 days 
after hatching. Effects of starvation and temperature on larval survival are dis- 
cussed. The number of zoeal stages in the development of this species is variable, 
as it is in other diogenids which have been studied in the laboratory, glaucothoes 
of this species being obtained after four or five zoeal instars. Descriptions and 
illustrations of the zoeal stages and the glaucothoe are presented. No other larvae 
of this genus have been described and intra-generic comparisons of larval mor- 
phology were not possible, but a comparison was made of the zoeal and glaucothoe 
stages of this species with those of others in the family. 
The eastern Pacific contains a relatively rich 
hermit crab fauna but one which is still rather 
poorly known systematically. In spite of the 
great number of species which occur even in 
shallow waters from Alaska to the Equator, very 
little is known concerning the life histories or 
larval development of eastern Pacific hermit 
crabs. One of the first successful attempts to 
rear anomuran larvae in the laboratory was 
made by Hart (1937), who described larval 
stages of two species of Pagurus and one of 
Paguristes and of the mud shrimp Upogebia, 
all from British Columbian waters. Coffin 
(I960) studied another species of Pagurus. No 
papers describing development of any tropical 
eastern Pacific hermit crab have been published. 
The genus Trizopagurus occurs in tropical 
seas around the world with the exception of the 
Caribbean (Forest, 1952). In the eastern Pa- 
cific, the genus is represented by T. magnificus, 
a not uncommon hermit crab of moderate size, 
1 Contribution No. 830 from the Institute of 
Marine Science, University of Miami, Miami, Florida. 
This work was supported by research grants Nos. 
16298 and GB-4305 from the National Science 
Foundation and grant No. GM-11244 from the Insti- 
tute of General Medical Sciences, U. S. Department 
of Health, Education and Welfare. Manuscript re- 
ceived September 14, 1966. 
black with orange spots and orange antennae 
and antennules. The species was first described 
by Bouvier (1898) as Clibanarius magnificus, 
and was redescribed and illustrated by Boone 
(1932) as Clibanarius chetyrkini. Forest (1952) 
recognized it as belonging to his newly estab- 
lished genus. The species is distributed from 
the Gulf of California southward at least as far 
as La Plata Island, Ecuador, and occurs also 
in the Galapagos Islands, but nothing is known 
of its ecology. The limited data available from 
various systematic papers which have dealt 
with T. magnificus and the data accompanying 
specimens in various collections are sufficient to 
indicate that this species seems to prefer rocky 
areas, from the intertidal zone down to a few 
tens of meters. The female from which the 
larvae were obtained for the present study was 
collected in an area where the substrates con- 
sisted of rocky patches surrounded by mud. 
Species collected with Trizopagurus in this lo- 
cality included Dardanus s inis tripes Stimpson 
and Clibanarius panamensis Stimpson, both 
typical of inshore waters along the major part 
of the range of T. magnificus. C. panamensis 
is most often found in brackish water and 
muddy areas, often close to mangrove shores. 
Also collected with adults of T. magnificus were 
a species of Isocloeles, about which virtually 
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