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| Advenasciaena bruneiana & Bruneisciaena schwarzhansi Kocsis, Lin, Bernard & Johari, 2024 |
ABSTRACT
We report here diverse Late Miocene fish assemblages based on otoliths collected from sedimentary rocks deposited in coastal marine settings in northern Borneo (Seria and Miri formations and Tutong beach). Surface-collected, large-sized otoliths, representing > 96% of the whole assemblage, are dominated by the families Sciaenidae and Ariidae, while Haemulidae, Engraulidae, and Lactaridae can be common at certain sites. Additional taxa were revealed by screen-washing of the sediments from selected sites including taxa from the families of Congridae, Bregmacerotidae, Apogonidae, Gobidae, Sillaginidae, and Cepolidae. Among the sciaenids, we describe six new taxa (Advenasciaena bruneiana, Atrobucca borneensis, Bruneisciaena schwarzhansi, Nibea ambugensis, Nibea stintoni, and Protonibea nolfi), and we also report the first fossil occurrence of some other groups (e.g. Lactarius lactarius, Acanthocepola sp.) from the Indo-Australian Archipelago (IAA). All these discoveries add to our understanding of fish palaeobiodiversity in the IAA where today’s highest marine biodiversity exists. The compositions of the faunas reflect a shallow marine coastal palaeoenvironment with close connection to estuaries where some of the reported fishes might have migrated seasonally or daily with the tide. Turbid, suspension-loaded water might be also presumed, where ariids, sciaenids, and the haemulid Pomadasys are often observed today.
KEYWORDS: Teleost otoliths, shallow-water tropical fauna, palaeobiodiversity, new genera, Indo-Australian archipelago, fossil fish fauna
Order incertae sedis in Eupercaria Betancur-R. et al., 2017
Family Sciaenidae Cuvier, 1829
Genus Advenasciaena gen. nov.
Name: Advena refers to the strange, alien characteristic of these new sciaenid otoliths.
Advenasciaena bruneiana sp. nov.
Name: Referring to Brunei Darussalam, the country of origin.
Distribution: From late Middle Miocene to Late Miocene layers of the Seria and Miri formations in Brunei Darussalam.
Genus Atrobucca Chu, Lo and Wu, 1963
Atrobucca borneensis sp. nov.
Name: Refers to the origin of the otoliths as they are found on Borneo Island.
Genus Bruneisciaena gen. nov.
Name: Refers to the geographic origin of the new sciaenid genus (Brunei Darussalam).
Bruneisciaena schwarzhansi sp. nov.
Name: In honour of Werner Schwarzhans (Hamburg, Germany) due to his great works on sciaenid otoliths.
Distribution: From late Middle Miocene to Late Miocene layers of the Seria and Miri formations in Brunei Darussalam.
Genus Nibea Jordan and Thompson, 1911
Nibea ambugensis sp. nov.
Name: Derived from the locality of Ambug Hill (Tutong District, Brunei Darussalam) where these otoliths are the most abundant.
Nibea stintoni sp. nov.
Name: In memory of Fred C. Stinton who first worked on fossil otoliths from Brunei.
Genus Protonibea Trewavas, 1971
Protonibea nolfi sp. nov.
Name: In honour of Dirk Nolf for his major contributions to otolith research.
Conclusion: Our study reports diverse coastal marine fish faunas based on otoliths from the Neogene beds of Brunei Darussalam in Borneo. The recovered 1493 otoliths belong to 34 taxa of 11 families, and among them six new species and two new genera (Advenasciaena bruneiana gen. nov. sp. nov., Atrobucca borneensis sp. nov., Bruneisciaena schwarzhansi gen. nov. sp. nov., Nibea ambugensis sp. nov., Nibea stintoni sp. nov., and Protonibea nolfi sp. nov.) are reported. The overall fauna is dominated by Sciaenidae, followed by Ariidae, Haemulidae, Engraulidae, and Lactariidae. Most of these specimens were collected from the surface of the outcrops, however, other families were revealed by occasional screen-washing (Gobiidae, Sillaginidae, Bregmacerotidae, Apogonidae, Congridae, and Cepolidae). Many of these groups are represented only by a few specimens and collectively the micro-remains compose 3.7% of the entire fauna. Future bulk sampling of the sediments could shed further light on the abundance and diversity of the micro-otolith assemblages. Based on the large-sized otoliths, the fish fauna indicates a palaeoenvironment with a coastal marine setting with nearby estuaries and deltas, probably with turbid water and, from time to time with lower salinity conditions. The younger deposits of the Seria Fm (AH) may reflect more open marine connections but still with a shallow setting with close proximities of river inputs. When comparing our findings with modern biodiversity and previous studies of the fossil record from the region, it is evident that our results increase our understanding of fish palaeobiodiversity in the Indo-Australian Archipelago, where today’s highest marine biodiversity exists. The described faunas and new taxa further highlight that the region’s fossil record is understudied, and new palaeontological findings are expected in the future.
László Kocsis, Chien-Hsiang Lin, Emma Bernard and Adibah Johari. 2024. Late Miocene Teleost Fish Otoliths from Brunei Darussalam (Borneo) and their implications for palaeoecology and palaeoenvironmental conditions. Historical Biology: An International Journal of Paleobiology. DOI: 10.1080/08912963.2023.2271489
