World Congress of Malacology Antwerp ... - Unitas Malacologica

DNA studies using both nuclear (ITS-1) and mitochondrial (COI sub. 1) DNA suggest a recent
hybridization event between A. attenuata (Fagot, 1886) and A. secale. The A. attenuata mitochondrial
and nuclear haplotypes show an introgression pattern into A. secale, that is consistent with the
geographical distributions of the taxa. The remaining ‘secale’ haplotypes suggest temporary isolation
with clade distributions associated with river valleys in northern Spain. The genetic patterns are
geographically coherent but conspicuously inconsistent with shell morphology.
Karyotypes of land operculate snails genus Pterocyclus and Rhiostoma (Prosobranchia:
Cyclophoridae) from Thailand and Malaysia
Kongim; Bangon 1 ; Tongkerd, Piyoros 2 ; Sutcharit, Chirasak 2 ; Yasin, Zulfigar 3 ; Tan, Aileen 3 ;
Panha, Somsak 2
1. Department of Biology, Faculty of Science, Mahasarakham University, Kantharawichai District,
Mahasarakham Province 44150, Thailand,
Email: bungonk@yahoo.com
2. Animal Systematic Research Unit, Department of Biology, Faculty of Science, Chulalongkorn
University, Phyathai Road, Bangkok 10330, Thailand,
Email: Piyoros_Tongkerd@yahoo.com; Jirasak4@yahoo.com; somsakp@sc.chula.ac.th
3. Centre for Marine and Coastal Studies, Universiti Sains Malaysia, 11800 Pulau Pinang, Malaysia,
Email: dir_seas@usm.my; aileen@usm.my
The snorkel snails of the two related genera Pterocyclus and Rhiostoma collected from Thailand and
Malaysia were karyotyped. These genera showed distinct intrageneric similarities in both haploid and
diploid chromosome number (n = 14, 2n = 28) but the ranges of fundamental chromosome number
(FN) exhibit variation of 48, 52 and 56. Karyotyes of the two Pterocyclus species from south
Thailand and Malaysia show 8M + 4SM + 2T in Pterocyclus asiphon and 7M + 5SM + 2T in
Pterocyclus sp. The six species of Rhiostoma examined herein show the karyotypes variation with
chromosome morphology differentiation. The karyotype varied from 7M + 4SM + 3T in R. hainesi
from eastern Thailand. Two species from the south i.e. R. chupingense exhibits 6M + 5SM + 3T and
2M + 9SM + 3T in R. jalorensis. The two island species R. asiphon from Angtong Island has 3M +
8SM + 1T + 2A and 5M + 5SM + 2T + 2A in R. samuiense from Samui Island. Karyotypes among
populations of R. housei showed variation between the central (9M + 2SM + 3T) and southern
regions (9M + 2SM + 2T + 1A) of Thailand. This is the first report on chromosome study of the
peculiar land operculate snails of the Thai-Malay Peninsula. The systematic surveys of these snail
genera is now being critically studied.
Early ontogeny and micro-ornamentation of Nicaniella and Pressastarte (Bivalvia: Astartinae)
from the Jurassic of the Southern Baltic
Koppka, Jens 1 ; Malchus, Nikolaus 2
1. Institute of Geography and Geology, Fr.-Ludwig-Jahn-Str. 17a, D 17489 Greifswald, Germany,
Email: koppka@uni-greifswald.de
2. Dept. de Geología/Area Paleontologia, UAB campus, edifici C sur, 08193 Bellaterra, Catalunya,
Spain,
Email: n.malchus@gmx.net
This paper documents for the first time early ontogenetic shells and micro-ornaments of Nicaniella
and Pressastarte, two cosmopolitan genera of Jurassic Astartidae. Results are still preliminary and
taxonomy in a flux. Nevertheless, Nicaniella species can be shown to have clearly distinguishable
prodissoconch 1 and 2 stages, the latter with well developed growth rings; in contrast, Pressastarte
lacks a clearly defined P1 stage and the P2 has no obvious growth lines.
Micro-ornaments of the two genera consist of a superficial reticulation and pits of slightly larger size
than the net elements. Reticulation begins as irregular and widely spaced grooves of micrometre size
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