Data report: Miocene planktonic foraminifers Dentoglobigerina and Globoquadrina from IODP Sites U1489 and U1490, Expedition 363

International Ocean Discovery Program Expedition 363 Sites U1489 and U1490, located in the Western Pacific Warm Pool, contain diverse assemblages of planktonic foraminifers. We examined and imaged specimens of Miocene Dentoglobigerina and Globoquadrina to determine the presence or absence of spine holes and pustules in their wall texture. A total of 15 specimens were observed across six species, including Dentoglobigerina baroemoenensis, Dentoglobigerina binaiensis, Dentoglobigerina globosa, Dentoglobigerina globularis, Dentoglobigerina tripartita, and Globoquadrina dehiscens. Here we present scanning electron microscope and zstacking light microscope images in three views, including illustrations of their wall texture. Introduction Dentoglobigerina is a diverse genus of planktonic foraminifers that ranges from the middle Eocene to recent. The descendant genus Globoquadrina is currently monospecific, consisting of Globoquadrina dehiscens and ranging from the early to late Miocene (Wade et al., 2018). The taxonomy and biostratigraphy of Eocene and Oligocene Dentoglobigerina were reviewed by Olsson et al. (2006) and Wade et al. (2018), respectively, as part of the Paleogene Planktonic Foraminifera Working Group. However, the wall texture of Miocene Dentoglobigerina and Globoquadrina has not yet been examined in detail. The dentoglobigerinids are a difficult group; in addition to morphological variability is the issue that the wall texture and the presence and absence of spine holes are highly variable across the lineage. Research to date has not been able to determine whether or not spines are a conservative trait in Miocene Dentoglobigerina. Spine holes have not been observed in all species of Dentoglobigerina (Wade et al., 2018), mostly because of the difficulty in finding well-preserved specimens and the considerable time needed to locate them under a scanning electron microscope (SEM). However, given that the identification of spine holes is not evident in some species, it was suggested by Pearson and Wade (2015) that there could be two clades with similar morphologies, one spinose and one nonspinose, or that spines could have been lost through evolution. Pustules are also of interest for this study because they are frequently seen in umbilical shoulders of Dentoglobigerina specimens. Here we contribute to the debate on Miocene Dentoglobigerina and Globoquadrina wall texture and taxonomy through light microscope (z-stacking) and SEM examination of specimens from Sites U1489 and U1490 in three views (umbilical, edge, and spiral). We also include wall texture images and record the presence or absence of spine holes and pustules around the umbilical area. Site location and setting Seven sites were cored in 2016 during International Ocean Discovery Program Expedition 363 in the Western Pacific Warm Pool (Figure F1). We examined two sites to record the presence of Dentoglobigerina and Globoquadrina: Site U1489 cored four holes at 3400 meters below sea level (mbsl), and Site U1490 cored three holes at 2300 mbsl (Rosenthal et al., 2018a). This data report focuses on the Dentoglobigerina and Globoquadrina genera found in lower to middle Miocene sediments. The geological age of the sediment samples ranges from 22.13 to 13.27 Ma according to the shipboard age model (Rosenthal et al., 2018a). Site U1489 (02°07.19ʹN, 141°01.67ʹE) is situated on the western slope of the southern Eauripik Rise in the Caroline basin of Papua New Guinea (Figure F1; Rosenthal et al., 2018b). Site U1490 (05°48.95ʹN, 142°39.27ʹE) is located on the northern edge of the Eauripik Rise about 431 km north of Site U1489 (Figure F1; Rosenthal et al., 2018c). Of the seven total holes cored at Sites U1489 and U1490, Holes U1489D and U1490A are examined in the present study. Rosenthal, Y., Holbourn, A.E., Kulhanek, D.K., and the Expedition 363 Scientists Proceedings of the International Ocean Discovery Program Volume 363 publications.iodp.org https://doi.org/10.14379/iodp.proc.363.203.2020 Data report: Miocene planktonic foraminifers Dentoglobigerina and Globoquadrina from IODP Sites U1489 and U1490, Expedition 3631 Florent Fayolle2 and Bridget S. Wade2


Introduction
Dentoglobigerina is a diverse genus of planktonic foraminifers that ranges from the middle Eocene to recent. The descendant genus Globoquadrina is currently monospecific, consisting of Globoquadrina dehiscens and ranging from the early to late Miocene (Wade et al., 2018). The taxonomy and biostratigraphy of Eocene and Oligocene Dentoglobigerina were reviewed by Olsson et al. (2006) and Wade et al. (2018), respectively, as part of the Paleogene Planktonic Foraminifera Working Group. However, the wall texture of Miocene Dentoglobigerina and Globoquadrina has not yet been examined in detail.
The dentoglobigerinids are a difficult group; in addition to morphological variability is the issue that the wall texture and the presence and absence of spine holes are highly variable across the lineage. Research to date has not been able to determine whether or not spines are a conservative trait in Miocene Dentoglobigerina. Spine holes have not been observed in all species of Dentoglobigerina (Wade et al., 2018), mostly because of the difficulty in finding well-preserved specimens and the considerable time needed to lo-cate them under a scanning electron microscope (SEM). However, given that the identification of spine holes is not evident in some species, it was suggested by Pearson and Wade (2015) that there could be two clades with similar morphologies, one spinose and one nonspinose, or that spines could have been lost through evolution. Pustules are also of interest for this study because they are frequently seen in umbilical shoulders of Dentoglobigerina specimens.
Here we contribute to the debate on Miocene Dentoglobigerina and Globoquadrina wall texture and taxonomy through light microscope (z-stacking) and SEM examination of specimens from Sites U1489 and U1490 in three views (umbilical, edge, and spiral). We also include wall texture images and record the presence or absence of spine holes and pustules around the umbilical area.

Site location and setting
Seven sites were cored in 2016 during International Ocean Discovery Program Expedition 363 in the Western Pacific Warm Pool ( Figure F1). We examined two sites to record the presence of Dentoglobigerina and Globoquadrina: Site U1489 cored four holes at 3400 meters below sea level (mbsl), and Site U1490 cored three holes at 2300 mbsl (Rosenthal et al., 2018a). This data report focuses on the Dentoglobigerina and Globoquadrina genera found in lower to middle Miocene sediments. The geological age of the sediment samples ranges from 22.13 to 13.27 Ma according to the shipboard age model (Rosenthal et al., 2018a).
Site U1489 (02°07.19ʹN, 141°01.67ʹE) is situated on the western slope of the southern Eauripik Rise in the Caroline basin of Papua New Guinea ( Figure F1; Rosenthal et al., 2018b). Site U1490 (05°48.95ʹN, 142°39.27ʹE) is located on the northern edge of the Eauripik Rise about 431 km north of Site U1489 ( Figure F1; Rosenthal et al., 2018c). Of the seven total holes cored at Sites U1489 and U1490, Holes U1489D and U1490A are examined in the present study.
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Methods and materials
Sites U1489 and U1490 both recovered the lower and middle Miocene and were chosen for the relatively good preservation of planktonic foraminifers (Rosenthal et al., 2018b;Rosenthal et al., 2018c). Table T1 lists the samples analyzed, including their depth in the section and biostratigraphic age assignment. The site ages covered in this study were calibrated with the Miocene Planktonic Foraminiferal Zonation by Wade et al. (2011).
Dentoglobigerina and Globoquadrina specimens were picked manually from the residues of the >150 μm size fraction using a light microscope. A total of 15 specimens were selected across 5 samples based on their preservation. Images in three views (umbilical, edge, and spiral view) of the selected specimens were taken using an Olympus SZX10 z-stacking light microscope. A Jeol JSM-6480LV high-performance SEM from the UCL Earth Sciences laboratory was used to examine wall texture and assess the presence of morphological features, including spine holes and pustules, at higher resolution. Each stub was sputter-coated in an argon and gold atmosphere using a sputter-coater machine. Spine holes were investigated across the three views of each specimen's test, and the study focused on areas where pores were sufficiently preserved, pore ridges smooth, and not affected by diagenetic processes.

Results
At least six species belonging to the genus Dentoglobigerina, including its descendant G. dehiscens, were identified in five samples from Holes U1489D and U1490A. Morphological features (pustules and spine holes) of the wall texture of each Miocene specimen are recorded in Table T2, and images of each specimen are illustrated in Plates P1-P15. Overall, the preservation of specimens from Hole U1489D is better than for Hole U1490A.   Remarks: Wade et al. (2018) showed evidence for spine holes in D. baroemoenensis (pl. 11.1, fig. 12), but these were not observed by Fox and Wade (2013) (fig. 5.1c). In this report, we present additional evidence in Plate P1G-P1J with specimen S1 showing several spine holes at pore intersections in the umbilical, edge, and spiral views. One spine hole is also observed in the edge view of specimen S2 in Plate P2H. These features were found in isolated areas, mostly over the last chamber near (1) the apertural shoulders and (2) at the intersection of chambers in the spiral view. In contrast, specimens from Plates P3 and P4 did not reveal any spine holes because recrystallization and calcite overgrowth heavily obscure pore intersections. All the specimens lack pustules in the umbilical region. D. baroemoenensis was recorded in Subzone M1b and Zones M8 and M9. (Koch, 1935) (Plates P5, P6)

Dentoglobigerina globosa
Globoquadrina altispira globosa, Bolli (1957), p. 111, pl. 24, figs. 9a-10c Dentoglobigerina globosa, Wade et al. (2018), p. 348-350, pl. 11.6 Remarks: Fox and Wade (2013) did not record spine holes in the wall texture of D. globosa ( fig. 5.6c), whereas Wade et al. (2018) did not illustrate SEM wall texture images for this species (pl. 11.6). In this report, we document the first evidence of spine holes in specimen S7 (Plate P7H). Two spine holes are found in its edge view, isolated in the last chamber and close to an intersection with two other chambers. However, no spine holes are observed in specimen S8 in Plate P8, despite the good preservation. Recrystallization (Plate P9G, P9H) and dissolution (Plate P9I) obscure the identification of spine holes in specimen S9, illustrated in Plate P9. Pustules are observed in the apertural area of specimen S8 from Hole U1489D (Plate P8G), although they are not visible in specimens from Hole U1490A (Plates P7, P9). D. globosa was recorded in Zones M3 and M8 and Subzone M9a. (Bermúdez, 1961) (Plate P10)