Bray, Rodney A.

Cribb, Thomas H.

Hall, Kathryn A.

University of Queensland eSpace

Trematodes in Tangs:
species flocks and cluster 
observations
Kathryn A. Hall*1, Thomas H. Cribb1
and Rodney A. Bray2
1. Department of Parasitology, The University of 
Queensland, Brisbane, Qld, AUSTRALIA
2. Parasitic Worms Division, The Natural 
History Museum, London, UNITED 
KINGDOM
Gyliauchenidae Ozaki, 1933
■ endemic to herbivorous reef fishes 
in Pacific and Indian Oceans
¨Siganidae, Acanthuridae, Zanclidae, 
Scaridae, Pomacanthidae, 
Chaetodontidae.
■diagnosed by oesophageal bulb, 
posterior ventral sucker and 
terminal genitalia
OTUs from Zebrasoma
■Z. scopas and Z. veliferum sampled 
from Heron and Lizard Islands
■Heron Island:
¨Z. scopas: OTU1, OTU2
■ Lizard Island:
¨Z. scopas: OTU1, OTU2, OTU3
¨Z. veliferum: OTU4
Differences among OTUs
■ OTU1
¨pear-shaped pharynx
¨ oesophagus: single loop
¨diagonal testes
■ OTU2
¨ barrel-shaped pharynx
¨ oesophagus: single -
double loop
¨diagonal testes
■ OTU3
¨ barrel-shaped pharynx
¨ oesophagus: single loop
¨ symmetrical testes
■ OTU4
¨ barrel-shaped pharynx
¨ elongate ventral sucker
¨ elongate body
Multivariate Analysis
■previous uses for helminth 
taxonomy: Bray & Sophie, 1987
■new application for cluster 
observations and discriminant 
analysis
¨ isolates members of groups rather 
than characters for identification
Materials and Methods
■79 individuals measured
■Cluster observations (CO):
¨Ward and Complete linkage 
¨Pearson distances
¨OTU3 and OTU4 used as similarity 
indicators
■ cluster membership as indicator in 
discriminant analysis (DA)
Results
■OTUs grouped in loose clusters
■members of same cohort clustered 
well
■ group membership 100% accurate 
during DA
■ arbitrary alteration of true group 
detected and reassigned by DA
Conclusions
■CO and DA useful for determining 
group membership of unidentified 
samples
■ genetic closeness of cohort reflected 
in clusters
■ character development and change 
can be examined by clustering
Future directions
■ samples from Z. scopas from New 
Caledonia added into dataset
■ further collecting in Western 
Australia (Indian Ocean)
■ apply CO and DA to Gyliauchen
from Australian Siganus
■ trace character evolution for all 
gyliauchenids


Trematodes in tangs: species identification and cluster observations

https://espace.library.uq.edu.au/view/UQ:967b97a/UQ967b97a_OA.pdf

Trematodes in tangs: species identification and cluster observations

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