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Vol. 41 No. 3, 2002
Morphometric Analysis of Shell and Operculum Variations in the Viviparid Snail, Cipangopaludina chinensis (Mollusca: Gastropoda), in Taiwan
Yuh-Wen Chiu1,2, Hon-Cheng Chen2, Sin-Che Lee1 and Chaolun Allen Chen1,3*
1Institute of Zoology, Academia Sinica, Taipei, Taiwan 115
2Department of Zoology, National Taiwan University, Taipei, Taiwan 107
3Institute of Oceanography, National Taiwan University, Taipei, Taiwan 107
Yuh-Wen Chiu, Hon-Cheng Chen, Sin-Che Lee and Chaolun Allen Chen (2002) The viviparid snail, Cipangopaludina chinensis,
is one of the widely distributed freshwater gastropods in Asia, whose
intraspecific variations in shell morphology and operculum were thought
to be due to ontogenetic allometric growth or environmental effects. In
this study, morphometric analyses were applied to discriminate shell
and operculum variations in 251 individuals of C. chinensis
from 5 populations, including Chutzuhu, Laumay, Lantan, and Wanda in
Taiwan, and 1, Kwangju, in Korea. The allometric shell growth pattern
in C. chinensis was
identified using linear regression analysis. Thirteen shell and
operculum characters were measured and examined using multidimensional
scaling (MDS) and canonical discriminate analysis (CDA). These 2
analyses clearly demonstrated that 2 morphotypes, namely a tall-spired
form and a short-spired form, exist among the 5 populations. MDS
indicated that snails with the shorter shell spire in Chutzuhu and
Laumay were morphologically related. CDA suggested that spire height is
the most important character contributing to variation between these
populations. One of the factors causing variation in spire height
within and between populations is allometric growth. Different growth
rates between the spire and other portions of the shell result in the
shell changing shape with growth. Linear regression demonstrated that
the spire of the tall-spired form lengthens at a faster rate than that
of the short-spired form. Different growth rates in the spire thus
contributed to the major difference in shell shape between the 2
morphotypes. Ontogenetic allometric growth and environmental factors
that contribute to the configuration of the 2 morphotypes in C. chinensis are discussed.
Key words: Morphometric analysis, Viviparid snail, Allometric growth, Morphotype.
*Correspondence: Tel: 886-2-27899549. Fax: 886-2-27858059. E-mail: cac@gate.sinica.edu.tw
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