Ćorić, S. ; Galovic, I. ; Matošević, M.

2023 New calcareous nannofossils from the Middle to Late Miocene of the North Croatian Basin, Central Paratethys.

Published in: Journal of Nannoplankton Research, volume 41, part 1, pages 1-12.

DOI: https://doi.org/10.58998/jnr2059

Abstract:
One new genus (Jeremyella) and six new species (Jeremyella levkovii, Cruciplacolithus pavsicii, Reticulofenestra galovicorum, R. benicii, Praenoelaerhabdus galoviciae, Coronosphaera caputiae) of heterococcoliths and two new genera (Nivisolithus and Planolithus) and seven new species (Nivisolithus kovacicii, N. vrabacii, Planolithus mihajlovicii, P. eggeri, Isolithus pavelicii, I. kovacii, Micrantholithus cosoviciae) of nannoliths are described from the Middle to Late Miocene of the Paratethys. Isolithus pavelicii nomen nudum was not validly published previously and has therefore been correctly described herein. Based on the marker species determined in the assemblages, all of the new taxa are from Zones NN6 to NN8.

Howe, R.

2023 Taxonomic note – The status of Sphenolithus strigosus Bown & Dunkley Jones, 2006.

Published in: Journal of Nannoplankton Research, volume 41, part 1, pages 13-14.

DOI: https://doi.org/10.58998/jnr2125

Abstract:
no abstract provided

Young, J. R.

2023 Some proposed changes to the systematics of Cenozoic and Mesozoic nannoplankton.

Published in: Journal of Nannoplankton Research, volume 41, part 1, pages 15-25.

DOI: https://doi.org/10.58998/jnr2293

Abstract:
A series of changes are proposed to the systematics of certain nannoplankton taxa in order to resolve various taxonomic inconsistencies and anomalies. One new Cenozoic species––Calcidiscus thiersteinii––and one new Mesozoic species––Watznaueria leesiae––are proposed, along with 32 new Cenozoic combinations––Coccolithus floralis, Pletolithus hulliae, Reticulofenestra chriskingii, R. nicolasii, R. larae, R. artuziae, Gephyrocapsa maceria, Hornibrookina elegans, Syracosphaera franzii, S. isselii, S. magnaghii, Solisphaera miocaenica, Blackites mericii, B. perfectus, B. prolatus, B. elongatus, B. rothii, B. australensis, Ceratolithus vidalii, Craterolithus hirsutus, C. eolutetiensis, C. plenilutetiensis, Discoaster glenos, D. mexicanus, Lithostromation concavum, L. martinii, L. nodosum, L. hohnensis, L. pyramidale, Peritrachelina arenaria, P. minuta and Martiniaster menneri.

Jiang, S. ; Wang, Y.

2023 Triquetrorhabdulus nanhaiensis, a new early Middle Miocene nannolith species from the South China Sea.

Published in: Journal of Nannoplankton Research, volume 41, part 1, pages 27-32.

DOI: https://doi.org/10.58998/jnr2129

Abstract:
A new calcareous nannofossil species––Triquetrorhabdulus nanhaiensis sp. nov.––was observed during a routine post-cruise biostratigraphic study of the core-catcher and core materials obtained during International Ocean Discovery Program Expedition 368 to the rifted margin of the South China Sea. This large to very large nannolith is an elongate, triradiate, optically monocrystalline rod with the optical c-axis lying parallel to the length of the nannolith. The longitudinal core is enlarged and composed of three laths, with the vertically oriented lath reduced and bisecting the longitudinal core along its length slightly asymmetrically. It has two distinctively long, thin, straight, tapering spines that extend from the enlarged end of the nannolith. These unique spines are oriented nearly perpendicular. Its common abundance and short range of approximately 15.0–15.1 Ma, just below the upper boundary of Zone NN4, provides the potential for an additional datum event as well as for further investigations on the diversification of these nannoliths in the early Middle Miocene.

Lancis, C. ; Tent-Manclús, J. E. ; Flores, J-A.

2023 A new centrifugation/filtration technique to improve the observation of calcareous nannofossils under the scanning electron microscope.

Published in: Journal of Nannoplankton Research, volume 41, part 1, pages 33-39.

DOI: https://doi.org/10.58998/jnr2157

Abstract:
A new sediment sample preparation procedure for observing calcareous nannofossils using a scanning electron microscope (SEM) is described. The new preparation technique is a moderately time-consuming technique that allows observation of the finest structural details of specimens in the SEM. It has two separate steps: 1) disaggregation employing H2O2 and an ultrasound bath, keeping the pH stable through the use of a NaCO3-HCO3 buffer solution; and 2) a filtration process that concentrates and cleans the nannofossils through use of a vacuum pump. To do this, previous techniques for improving the quality of SEM images were combined, aimed at avoiding dissolution in the process, for which a slow digestion of the organic matter was carried out using a buffered solution, adding centrifugation and controlled vacuum pumping in order to retain the coccoliths without affecting their preservation.

Rosario, D. J. G. ; Geronia, M. C. M. ; Peleo-Alampay, A. M. ; Fernando, A. G. S.

2023 Morphometric study and statistical analysis of gephyrocapsids in surface sediments from offshore western Luzon and semi-enclosed bays in the Philippines.

Published in: Journal of Nannoplankton Research, volume 41, part 1, pages 41-54.

DOI: https://doi.org/10.58998/jnr2212

Abstract:
The dominance of Gephyrocapsa in the waters and surface sediments of the Philippines makes it ideal for morphological studies. An understanding of the morphology of this genus has been well developed over the years, and an informal nomenclature for specimens from Holocene sediments has been used in several studies. Bollmann (1997) established six categories––equatorial, oligotrophic, transitional, cold, larger and minute forms––based on variations in coccolith length and bridge angle. Each morphotype has been interpreted to have distinct ecological preferences. Results from measurements of placolith length and bridge angle in 1900 Gephyrocapsa coccoliths from surface sediments from offshore western Luzon (eastern South China Sea) and semi-enclosed bays in the Philippines (Lingayen Gulf, Subic Bay, Boac Bay, Calancan Bay) show the occurrence of the oligotrophic, equatorial and larger Gephyrocapsa morphotypes. The oligotrophic morphotype prevails in the majority of the water bodies studied, whereas the larger Gephyrocapsa morphotype manifests mostly in warmer waters. The morphometric results also suggest a separation of the equatorial forms, based on placolith length, into Types GE1 (>3.1 μm) and GE2 (<3.1 μm), with both forms having a bridge angle limit of >61o. A statistical analysis was conducted to confirm the applicability of Bollmann’s morphometric study and the Gephyrocapsa categories to the inland seas and warmer waters of the tropics. Using one-way analysis of variance, it was found that the equatorial and oligotrophic morphotypes were separated at a bridge angle of 61° and not the 56° of Bollmann (1997). The equatorial and larger morphotypes could be differentiated at a placolith length of 3.7 μm instead of the 3.9 μm proposed by Bollmann (1997). This suggests that studies on Gephyrocapsa morphometry from open-ocean samples are not entirely applicable to warmer tropical and inland seas.

Schueth, J. D.

2023 Systemic biases in micropaleontology: A case study of calcareous nannofossil taxonomic names.

Published in: Journal of Nannoplankton Research, volume 41, part 2, pages 54-62.

DOI: https://doi.org/10.58998/jnr3027

Abstract:
The names given to fossil genera and species describe physical characteristics, identify important geographic or stratigraphic information, or can be used to honor people. Yet taxonomy has a history of colonialism, with most taxa being named by men from Europe and North America. Compared to other paleontological subdisciplines, calcareous nannofossil micropaleontology is a newer field and is therefore assumed to have fewer entrenched biases. Here, I investigate the taxonomic etymology of calcareous nannofossils to determine how names reflect a known partiality in the geosciences, with a summary of taxon etymologies that demonstrates substantial geographic and gender biases. Despite many contributions from nannofossil paleontologists identifying as women, they are vastly underrepresented. Although international collaboration is crucial for acquiring data, trends also indicate a strong bias toward naming taxa after people, localities, and stratigraphy from Europe and North America. The propensity to use this limited range of descriptors indicates that paleontology and geosciences are plagued with implicit biases. Therefore, we must overcome social, cultural, economic, and geographic barriers to make calcareous nannofossil micropaleontology more inclusive and accessible for all genders, localities, and marginalized groups.

De Kaenel, E. ; Mojon, P. -O.

2023 Calcareous nannofossil biostratigraphy of the Eocene/Oligocene boundary (Zones NP19–21) in the parautochthonous Subalpine UMM of the Swiss Molasse Basin (Canton Fribourg, Western Switzerland).

Published in: Journal of Nannoplankton Research, volume 41, part 2, pages 64-96.

DOI: https://doi.org/10.58998/jnr3777

Abstract:
The upper Eocene parautochthonous Untere Meeres-Molasse (UMM = Lower Marine Molasse of the Swiss Molasse Basin) and Eocene/Oligocene boundary are present in the Vaulruz Formation of the Subalpine area in Canton Fribourg, Western Switzerland. In the Ruz section, the uppermost Priabonian to lowermost Rupelian sediments around the Eocene/Oligocene boundary are calcareous nannofossil rich with 130 reworked species of Paleocene–Eocene age (plus many others from the Late Cretaceous) and 129 non-reworked species from nannofossil Zones NP19–21, including Calcidiscus ellipticus, Calciosolenia aperta, Chiasmolithus nitidus, Chiasmolithus oamaruensis, Chiasmolithus titus, Coccolithus biparteoperculatus, Coccolithus cachaoi, Coccolithus scheri, Corannulus germanicus, Helicosphaera gartneri, Isthmolithus recurvus, Micrantholithus triquetra, Pontosphaera alta, Pontosphaera pectinata, Reticulofenestra laevis, Reticulofenestra oamaruensis, Sphenolithus apoxis, Sphenolithus bergenii, Sphenolithus puniceus, Sphenolithus truaxii, Transversopontis pulcheroides, Umbilicosphaera bramlettei, and Umbilicosphaera detecta. The Eocene/Oligocene boundary is well defined by the first occurrence of the key Rupelian marker Reticulofenestra circus (8–12 µm) in the lower part of Zone NP21. At the top of the section, upper Zone NP21 is characterized by Chiasmolithus altus, Cyclicargolithus abisectus, Furcatolithus akropodus, Helicosphaera robinsoniae, and Ilselithina fusa. In the lower part of the section, upper Priabonian sediments are characterized by Cribrocentrum reticulatum (>10 µm) for Zone NP19, as well as Ilselithina iris, Hughesius tasmaniae, and Transversopontis pax for Zones NP20 to lowermost Zone NP21. We present a comprehensive review of the structure of Ilselithina iris based on light microscope photomicrographs from the Oamaru type locality (New Zealand). We propose to emend the upper boundary of Zone NP19 of the standard calcareous nannofossil scheme of Martini (1971) with the last occurrence of Cribrocentrum reticulatum. Five new combinations are introduced: Cribrocentrum helianthus, Cribrocentrum nanggulanensis, Dictyococcites alabamensis, Reticulofenestra pelycomorpha, and Reticulofenestra rupeliensis.

Hagino, K. ; Young, J. R. ; Morono, Y.

2023 Molecular phylogenetic affinity of Hayaster cf . perplexus based on 18S rDNA sequences.

Published in: Journal of Nannoplankton Research, volume 41, part 2, pages 98-104.

DOI: https://doi.org/10.58998/jnr3439

Open PDF (open access)

Abstract:
A partial 18S rDNA sequence of Hayaster cf. perplexus (1674 bp) was obtained from an isolated cell from Tosa Bay, off the coast of Japan (NW Pacific Ocean), using the single cell PCR technique. In molecular phylogenetic analyses, the sequence of H. cf. perplexus fell in the Coccolithales clade and clustered with the sequences of the Coccolithaceae, Calcidiscaceae, an uncultured clone, and holococcolith-bearing taxa with very high posterior probability for Bayesian Inference analyses and very high bootstrap support for PhyML analyses. However, phylogenetic relationships among the sequences of H. cf. perplexus, Coccolithaceae, and Calcidiscaceae are uncertain due to low posterior probability and bootstrap values. These results suggest that the separation of the families Coccolithaceae and Calcidiscaceae may not be justified.

Guerra, R. M. ; Concheyro, A.

2023 A new Markalius species from the Cretaceous/Paleogene boundary of the Neuquén Basin (Argentina).

Published in: Journal of Nannoplankton Research, volume 41, part 2, pages 106-109.

DOI: https://doi.org/10.58998/jnr3615

Abstract:
Study of a Cretaceous/Paleogene (K/Pg) boundary section in the Jagüel Formation, Neuquén Basin, Argentina, has revealed a new calcareous nannofossil species, Markalius neuquenesis sp. nov. This new species is medium to large in size (7.3 to 8.03 µm), with a broad, birefringent tube cycle divided into four sectors, each with at least one small perforation. The species is rare to few in abundance in the upper Maastrichtian through lower Danian Jagüel Formation and has also been observed in the Danian of the North Atlantic Ocean.

Bown, P. R. ; Kim, H. ; Gibbs, S. J.

2023 Danian calcareous nannofossil evolution and taxonomy with focus on sites from the North Atlantic Ocean (IODP Expedition 342, Sites U1403 and U1407).

Published in: Journal of Nannoplankton Research, volume 41, part 2, pages 110-157.

DOI: https://doi.org/10.58998/jnr3943

Abstract:
Danian nannofossil taxonomy is problematic because many of the new taxa that appeared in the aftermath of the Cretaceous/Paleogene (K/Pg) mass extinction were exceptionally small (less than 3 μm), simply constructed, morphologically similar, and inconspicuous when observed using cross-polarised light microscopy. As both identification and classification are challenging, this makes comparison of data from different workers difficult, and significantly hinders the analysis of broader questions regarding post-extinction evolutionary rates and the timing of ocean recolonisation and ecosystem recovery. Here we provide an illustrated account of Danian nannofossil taxonomy using two Integrated Ocean Drilling Program Expedition 342 sites, U1403 and U1407, that together provide a complete Paleocene composite section with good calcareous nannofossil preservation. Site U1403 includes a K/Pg boundary section that has an intact spherule layer and appears to be stratigraphically complete. The Site U1407 section is incomplete across the boundary interval due to a stratigraphic gap, but above this there is an almost complete Paleocene section with good nannofossil preservation. We describe the Danian nannofossil recovery succession recorded at both sites, focusing particularly on the survivorship record and emergence of new Cenozoic lineages. The sites reveal a succession of acme intervals, recording the incoming of new taxa and lineages, with Neobiscutum, Cruciplacolithus, Praeprinsius, Coccolithus, and Toweius being especially notable. We attempt to bring consistency to the taxonomy of these groups and address the practicality and logic of the higher taxonomy, especially the use of the genera Prinsius, Praeprinsius, Futyania, and Toweius.