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| Orbitestella amphaengensis Ketwetsuriya & Dumrongrojwattana, 2021 |
Abstract
A new species of microgastropod, Orbitestella amphaengensis, is described from Holocene Bangkok clay, where a whale’s skeleton (3,380 ± 30 years old) was found, in Samut Sakorn Province, Central Thailand. This new orbitestellid species is characterised by the presence of prominent keels, characteristics of nodules, spiral series, and numerous axial ribs. The new species is the oldest microgastropod of this family hitherto reported in Thailand and is also the first record of the genus Orbitestella. The presence of this marine microgastropod indicates that the depositional environment was shallow marine deposits.
Key words. Gastropod, new species, taxonomy, Holocene, diversity
Superorder Heterobranchia Gray, 1840
Family Orbitestellidae Iredale, 1917
Orbitestella Iredale, 1917
Type species. Cyclostrema bastowi Gatliff, 1906.
Diagnosis. Shell thin, pellucid, discoidal, dextral, of few whorls and of peculiar sculpture: widely umbilicate; columella vertical; aperture never varied, irregular in shape, edges thin.
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| Holotype of Orbitestella amphaengensis, new species (ESKU-2021-I-001). A, apical view; B, early whorl; C, front view; D, protoconch; E, umbilical view; F, close-up of umbilical view. |
Orbitestella amphaengensis, new species
Diagnosis. Shell thin, pellucid, discoidal, dextral, of few whorls and of peculiar sculpture: widely umbilicate; columella vertical; aperture never varied, irregular in shape, edges thin.
Etymology. After Amphaeng Sub-district, where the studied gastropod material was found.
Chatchalerm Ketwetsuriya and Pongrat Dumrongrojwattana. 2021. A New Microgastropod Species, Orbitestella amphaengensis, (Gastropoda: Heterobranchia: Orbitestellidae) from Bangkok Clay of Samut Sakorn Province, Thailand. RAFFLES BULLETIN OF ZOOLOGY. 69: 304–308
