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Vol. 49 No. 1, 2010
Karyotype Variations in the Genus Pollicaria (Caenogastropoda:
Pupinidae)
Bangon
Kongim1, Chirasak Sutcharit2, Piyoros Tongkerd2,
Shau-Hwai Aileen Tan3, Nguyen Xuan Quynh4, Fred
Naggs5, and Somsak Panha2,*
1Department
of Biology, Faculty of Science, Mahasarakham University, Kantharawichai
District, Maha Sarakham 44150, Thailand
2Animal Systematics Research Unit, Department of
Biology, Faculty of Science, Chulalongkorn University, Bangkok 10330,
Thailand
3School of Biological Sciences, Universiti Sains
Malaysia, Minden, Penang 11800, Malaysia
4Faculty of Biology, Hanoi University of Science, 334
Nguyen Trai, Thanh Xuan, Hanoi, Vietnam
5Department of Zoology, The Natural History Museum,
London SW7 5BD, UK
Bangon Kongim,
Chirasak Sutcharit, Piyoros Tongkerd, Shau-Hwai Aileen Tan, Nguyen Xuan
Quynh, Fred Naggs, and Somsak Panha (2010) The
karyotypes of 4 recognized Southeast Asian species of the genus
Pollicaria were examined. All 7 populations studied were found to
possess the same chromosome pattern: n
= 13, 2n = 26. However,
the fundamental chromosome number (FN) of both populations of P. elephas
from the south (Malaysia) was 46, while those for the other 3 species
(5 populations) were all 50. Moreover, although each species had
a unique karyotype, the karyotype of the isolated species, P. elephas,
differed from the other 3 northern species in exhibiting 3 distinct
telocentric chromosomes (2m+6sm+2st+3t). The 3 smaller species, P. mouhoti from northeastern
Thailand, P. myersii from
Laos, and P. gravida
from 2 localities in northern Vietnam, exhibited similar karyotypes of
6m+4sm+2st+1t, 4m+6sm+2st+1t, and (3m+7sm+2st+1t and 2m+8sm+2st+1t)
respectively, with only 1 telocentric chromosome. The karyotypes
of the 2 morphologically variant populations of P. gravida from Vietnam differed by
1 in the number of metacentric and submetacentric chromosomes.
The genus Pollicaria
exhibits slight rearrangements in the centromeric positions of the
smaller chromosomes and the deletion of 1 chromosome pair. A
ZZ-ZW sex-determining system is proposed for this genus.
Key words: Operculate
snails, Pollicaria, Karyotype
variation, Sex determination, Sex chromosome.
*Correspondence: Tel and Fax: 66-2-2185273.
E-mail:somsakp@sc.chula.ac.th; somsak.pan@chula.ac.th
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