Early Pliocene Ostracoda from the Jemmys Point Formation, Gippsland Basin, southeastern Australia: nearshore and offshore origins of biodiversity

Abstract Early Pliocene ostracod faunas of the Jemmys Point Formation, onshore Gippsland Basin, yield a rich and well-preserved marine ostracod fauna of mixed shallow marine and deep marine origins. The ostracod faunas evidence a marine continental shelf palaeoenvironment that, during the deposition of one stratigraphic interval, was influenced by a strong, persistent upwelling current. This upwelling current allowed the migration of deep-sea Ostracoda (Philoneptunus sp.) onto the continental shelf. The deeper marine aspect of this early Pliocene fauna, and of modern ostracod faunas from the Bass Strait region, evidence the adaptation of deep shelf taxonomic clades to shallow cool temperate shelf environments and highlights one unusual evolutionary mechanism that has contributed to modern Bass Strait shallow marine biodiversity. Four species are newly described: Neonesidea chapminuta sp. nov., Tasmanocypris salaputia sp. nov., Oculocytheropteron jemmyensis sp. nov., and Philoneptunus plutonis sp. nov. Abbey P. McDonald* [a.mcdonald@deakin.edu.au], School of Life and Environmental Sciences, Deakin University, Burwood, Victoria 3125, Australia; Elizabeth A. Weldon [l.weldon@deakin.edu.au], School of Life and Environmental Sciences and Deakin Marine Research and Innovation Centre, Deakin University, Burwood, Victoria 3125, Australia; Mark T. Warne [mark.warne@deakin.edu.au], School of Life and Environmental Sciences and Deakin Marine Research and Innovation Centre, Deakin University, Burwood, Victoria 3125, Australia, and Museums Victoria, GPO Box 666, Melbourne, Victoria 3001, Australia.

THE JEMMYS POINT FORMATION is a broadly transgressive lithostratigraphic unit that is widespread in the Lakes Entrance region of southeastern Australia.In this region, it is predominately of Pliocene age and is composed of richly fossiliferous marls and sand (Wilkins 1963, Carter 1964, Gallagher & Holdgate 2003).This article presents the first comprehensive study on the taxonomy and palaeoecology of the Jemmys Point Formation ostracod faunas, which further evidence a major marine faunal turnover during the Miocene to Pliocene transition in southeastern Australia (Warne et al. 2003, McDonald & Warne 2022).
The age of the Jemmys Point Formation has been debated widely.Early views included those of Dennant (1891), who noted that the clay-rich beds of the formation were 'undoubtedly' Miocene in age, and Hall & Pritchard (1902) who also inferred a Miocene age.Singleton (1941) defined the southeastern Australian Kalimnan geological stage based on marine to lagoonal Jemmys Point Formation beds in road cut exposures along the Princes Highway near Kalimna, Victoria; both he and Carter (1964), among others, regarded these beds as Pliocene in age.Wilkins (1963) and Darragh (1985) considered the Jemmys Point Formation in the Lakes Entrance area to range in age from latest Miocene to Early Pliocene equivalent to the southeastern Australian Cheltenhamian and Kalimnan geological stages. However, Mallet (1977, 1978) determined the Jemmys Point Formation in the Lakes Entrance area to be generally of Pliocene age based on planktonic foraminiferal occurrences (in particular the presence of Globoconella punticulata); a view supported by Wallace et al. (2005, fig. 11).The Jemmys Point Formation beds sampled for this study are here considered Early Pliocene in age based on new strontium isotope dates of shell materials, and encompass the late Cheltenhamian and Kalimnan geological stages of southeastern Australia (sensu Warne, 2020), which broadly correlate with the Zanclean Stage of the international chronostratigraphic scale (Cohen et al. 2013(Cohen et al. , updated 2023)).
The Pliocene sediments of the Jemmys Point Formation are the final phase of marine deposition of the Seaspray Group within the Gippsland Basin (Hocking 1976).There is a notable change in overall ocean water depths (shallowing) across the Gippsland Basin around this time (Warne 1993(Warne , 2012(Warne , 2020)), which is in part reflected by the sediments and fossil faunas of the Jemmys Point Formation (Warne et al. 2003).It has also been argued (Warne 2012, Warne & Soutar 2012, McDonald & Warne 2022) that the initiation of regional tectonic uplift during the Late Miocene (Hill et al. 1995, Dickinson et al. 2002), referred to as the Kosciusko Uplift, caused a significant geogeographical broadening of shallow marine conditions across southeastern Australia, particularly in the Bass Strait region.
The aims of this article are to (1) delineate the systematic taxonomy of the ostracod fossils present in the Jemmys Point Formation, including the description of new taxa, (2) contribute to the understanding of the origins of southeastern Australian ostracod biodiversity, and (3) to investigate the palaeoenvironmental, palaeoecological and palaeoceanographical implications of the studied fossil assemblages.

Sample localities
Sediment samples from eight sedimentary levels from two localities within the lower Jemmys Point Formation were collected and processed for ostracod fossils.At the first locality, five beds were sampled from lakeside outcrops adjacent to the end of Ferndale Parade, Lakes Entrance.At the second locality, three beds were sampled from an exposure adjacent to Kalimna Jetty, Kalimna (Fig. 1).The two localities derive from relative low elevation exposures of the Jemmys Point Formation within the Lakes Entrance-Kalimna region.The interval exposed at the Kalimna Jetty location is slightly higher in the stratigraphic succession than that at the Ferndale Parade locality.
The Ferndale Parade locality at Lakes Entrance, Victoria (37.875 � S 147.988 � E, Datum WGS84) is a shoreline outcrop.It consists of several sedimentary beds made up of grey fossiliferous clays and black sands (Fig. 2C).Samples from five beds were collected; however, only four contained calcareous fossil material.The sampled strata are: LE1.Shore platform bed directly in front of low coastal bank exposure (Fig. 2B).LE2.Lowest bed of low-bank outcrop, directly adjacent and above LE1 (Fig. 2B).LE3.Middle clay bed above LE2 and immediately below a black sand bed (Fig. 2A, B).LEB.Black, quartz-rich and carbonaceous sand bed between LE3 and LE4.No calcareous fossil material present; presumed to be of non-marine origin (Fig. 2A, B).LE4.Top layer of low-bank outcrop, above LEB (Fig. 2A).
a series of micron sieves (250 mm, 125 mm, 63 mm) to collect shelly material, then dried at 60 � C. Six hundred ostracod valves from each layer were collected, except from LEB sample material, which contained no calcareous fossils.This is because a minimum of 200-300 individuals, or 600 valves in terms of bivalved ostracods, in an assemblage is considered standard to document moderate faunal diversity from one location (Danielopol et al. 2002, Boomer et al. 2003).Picked specimens were mounted using gum tragacanth onto microfossil grid slides for identification.
Ostracod assemblages from all samples from these two localities include multiple growth stages with little evidence for post-mortem transportation or fossil reworking.Potential biases generated by laboratory processing through sample cross-contamination, specimen breakage and/or inadequate slide fixation (Danielopol et al. 2002), were minimized or avoided by (1) handling only one sample at a time, (2) cleaning equipment between samples (thoroughly scrubbing sieves and drying them with compressed air, and inspecting before use), (3) by avoiding the use of unnecessary force when rinsing and sieving samples and (4) by careful mounting of specimens on slides prepared with adequately concentrated water soluble glue.Specimens from each identified species, except in the case of insufficiently represented species, damaged or poorly preserved specimens (usually due to secondary diagenetic accretion of calcite), were selected for imaging.A Jeol IT300 scanning electron microscope (Japan) was used with an acceleration voltage of 5.0 kV to image specimens.

Kalimna Jetty-Jemmys Point area
The stratigrapher F.A. Singleton observed that 'a natural section, not more than 10 feet in height [approximately 3 metres], is given by the low cliffs which extend from Kalimna Hotel Jetty eastwards for threequarters of a mile [approximately 1.21 km] past Jemmy's Point to the bridge which connects the latter with Lakes Entrance [township]' (Singleton 1941, p. 40).He also noted that Jemmys Point Formation strata were well exposed in a road cutting along the Princes Highway between Kalimna and the bridge over the North Arm of the Gippsland Lakes that leads to Lakes Entrance.Within this road cutting section, Singleton (1941) identified a more extensive succession of calcareous fossiliferous Jemmys Point Formation strata of some 40 ft [approximately 12 m] thickness and recognized two distinctive shell beds-a 'lower shell bed' dominated by Eucrassatella specimens approximately 2 m from the base of the roadcut section, and an 'upper shell bed' approximately 11 m from the base of this section.Singleton (1941) designated this section as the stratotype for the local southeast Australian Kalimnan geological stage.Unfortunately, the strata within the road section along the Princes Highway are overgrown, and not safe to sample.However, our Kalimna Jetty sample site is equivalent to Singelton's (1941) 'Kalimna Hotel Jetty' site, this locality occurring low within the exposed succession of Jemmys Point Formation near Kalimna, north of the Princes Highway bridge.Mallett (1977) recorded the planktonic foraminifera in the Jemmys Point Formation from along the Princes Highway roadcut section between Kalimna and Lakes Entrance.From low in this Princes Highway roadcut succession of strata, he recorded common to fairly common occurrences of Globigerina bulloides, Globigerinoides trilobus, Orbulina suturalis/ Orbulina univera, Globigerina quinqueloba, Neogloboborotalia acostaensis, Globorotalia crassaformis and Globoconella punticulata, among other species.Some records of Mallett (1977) are of taxa that may have been reworked or are of uncertain identity (e.g., Globoquadrina dehiscens, Globorotalia sp.cf G. margaritae).High in this sequence, the same nominated species were recorded, some with lower abundance, in addition to the rare occurrence of Globoconella sp.cf.G. inflata.Sporadic occurrences of Globoturborotalia decoraperta, Globorotalia conomiozea and Dentoglobigerina altispira are also recorded throughout the sequence, and Globoturborotalia nepenthes and Globorotalia truncatulinoides are recorded as absent from this roadcut succession (Mallett, 1977).Relevant last occurrence (LO) and first occurrence (FO) records of some of these species include: G. nepenthes LO 4.20 Ma (Li et al. 2003)/   (Li et al. 2003) and D. altispira LO 3.09 (Li et al. 2003)/ 3.46 Ma in the Pacific (Wade et al. 2011).As indicated by Mallett (1977) the overall planktonic foraminifera occurrences from low within the Jemmys Point Formation near Kalimna suggest an Early Pliocene age.At one outcrop location along the southern Victorian coastline (southeast Australia) at Portland, within Whalers Bluff Formation of the Otway Basin, Early and Late Pliocene planktonic foraminifera faunas occur in direct superposition (see discussion by Warne & Soutar 2012).Planktonic foraminifera faunas of the lower Jemmys Point Formation exposures near Kalimna better correspond in terms of faunal occurrences, with the Early Pliocene faunas of the Whalers Bluff Formation as discussed by Warne & Soutar (2012).
The above biostratigraphical data for the Kalimna-Jemmys Point area suggests that the local southeast Australian Kalimnan Stage correlates with the upper part of the European/international Zanclean Stage (see fig. 10 of Warne, 2020).Darragh (1985) characterized his Kalimnan fossil molluscan assemblage from these exposures of the Jemmys Point Formation.Thus, our Jemmys Point Formation sample from Kalimna Jetty (low in the exposed sequence around Kalimna), is most likely to be of Early Pliocene (Zanclean) age, based on the above palaeontological data.Darragh (1985) defined a succession of fossil molluscan assemblages, from calcareous mud (marl) and sand facies, through the Cenozoic of southeastern Australia, based on the principle of superposition.Using this biostratigraphical method, he indirectly determined via correlation that the shoreline exposure of Jemmys Point Formation at the end of Ferndale Parade, Lakes Entrance, predated exposures of the same formation cropping out near Kalimna Jetty and Jemmys Point.Mallett (1977) did not record the planktonic foraminifera fauna of the Jemmys Point Formation from the Ferndale Parade location (east bank of North Arm of Gippsland Lakes).However, he did record a planktonic foraminifera fauna from a location along the west bank of the North Arm of the Gippsland Lakes (near high water mark), which likely contains the same molluscan assemblage as the Ferndale Parade location (Mallett 1977, Darragh 1985, Beu and Darragh, 2001).From this exposure along the west bank of the North Arm, Mallett (1977) recorded an Early Pliocene planktonic foraminifera fauna, which he suggested slightly predates the Jemmys Point Formation planktonic foraminifera faunas recorded from along the Princes Highway near Kalimna.In terms of local southeast Australian geological stages, Darragh (1985) considered the Jemmys Point Formation shoreline exposure adjacent to the end of Ferndale Parade, Lakes Entrance to be Cheltenhamian in age (i.e., pre-Kalimnan).However, Mallett (1977Mallett ( , 1978) ) considered all exposures of the Jemmys Point Formation he studied in the Lakes Entrance and Kalimna areas of the Gippsland Basin to be younger than marine beds exposed in coastal cliffs at Beaumaris within the Port Phillip Basin (Sandringham Sands)-the latter constituting the stratotype of the Cheltenhamian Stage.Thus, the uppermost Miocene Sandringham Sands succession at Beaumaris is here considered early Cheltenhamian in age, whereas the Lower Pliocene Jemmys Point Formation succession exposed along the shoreline adjacent to the end of Ferndale Parade, Lakes Entrance, is here considered late Cheltenhamian in age.

Strontium radioisotope dating of the Jemmys Point Formation
Sr-isotope dating was undertaken on shell specimens from four sampled sedimentary beds; three from the Ferndale Parade, Lakes Entrance locality (LE2, LE3, LE4) and one from the Kalimna Jetty locality (KJ3).These four beds were selected because of the presence of common invertebrate macrofossil shell material.Where possible, well-preserved brachiopod shell material was used for dating.However, where no suitable brachiopod specimen was present in a sample, the cleanest and most intact shells of unidentified bivalves were used.For sample LE3 brachiopod material was used for Sr-isotope dating, whereas for LE2, LE4 and KL3 molluscan materials were used.
Strontium radioisotope dating was conducted by the University of Queensland Radioisotope Facility (https://sees.uq.edu.au/research/facilities/radiogenic-isotope-facility), the results of which were normalized to the standard SRM (NST) 987 and interpreted via the LOESS Sr isotope lookup table (McArthur et al. 2020).The results (  (Mallett 1977(Mallett , 1978)).However, the mean age determined for strata at the Kalimna Jetty locality, nonetheless, appears anomalous, as the mean age result predates that for stratigraphically lower beds at the end of Ferndale Parade.This might be explained by the presence of the euryhaline ostracod species Mckenziartia portjacksonensis (McKenzie 1967) within the Kalimna Jetty assemblages, which suggests a small influence of freshwater input into otherwise close to normal marine conditions judging by most other elements of the ostracod fauna.This euryhaline species, which can tolerate some fluctuation in salinity and is common in modern nearshore to marginal marine environments (Warne 2005, Warne & Soutar 2012), is not present in any of the Lakes Entrance assemblages.Srisotope analyses conducted on shells from marginal marine waters can yield artificially older age results due to salinity induced change in the ratio of strontium isotopes (Bryant et al. 1995).Alternatively, it might be that the mean age results for the shoreline Ferndale Parade location, which is presently 0-1 m above water level, may have been subject to the post depositional influence of circulating porewaters derived from seawater, and impacted by consequent but unidentified diagenetic alteration of biogenic carbonate, resulting in mean ages younger than true depositional age (e.g., Lavelle 1998).
Thus, although some uncertainty exists about the overall age range and precise age correlations for different outcrops of Jemmys Point Formation strata in the onshore region of the Gippsland Basin, our strontium isotope data from locations in the immediate

Repository for specimens
All examined ostracod specimens from this study are housed in the NMV (National Museum of Victoria) Palaeontology Collection stored as microfossil assemblage slides (accession numbers NMV P344663-NMV P344669) or on individual microfossil slide grids for holotypes, paratypes and all figured specimens (accession numbers NMV P344537-NMV P344662).

Results
From all assemblages across the two study localities, 4200 ostracod valves were collected including representatives of 47 species from 31 genera (Tables 2, 3).Fortysix specimens represent indeterminate species, predominately due to these specimens being juveniles or because of poor preservation.In the case of specimens that were not identifiable to the species level, these were assigned to a genus where possible and left in open nomenclature.Of the identified species within the assemblages, eighteen are extant, which allows palaeoenvironmental interpretations (Table 4) to be informed by the known modern ecology of these species.
The following systematic taxonomy section includes synonymy lists that, where possible, encompass relevant references including original species descriptions.For some widely cited species, references discussing specimens from areas and times different from the focus of this study may not be included.

Remarks
Neonesidea chapmani has been identified from the late Eocene to Miocene of New Zealand (Ayress 1993(Ayress , 1995(Ayress , 2003)), in Miocene deposits in southeastern Australia (Whatley & Downing 1983, Warne 1987, 1988, McHenry 1996, Neil 2006, McDonald & Warne 2022), and in the Holocene of Bass Strait (Yassini & Jones 1995).This species has also been identified in mid-Miocene assemblages reflective of offshore continental shelf palaeoenvironments (Whatley & Downing 1983, Warne 1987Warne , 1988)).Extant examples of the fossil species have been found in shallow, open marine environments (Yassini & Jones 1995).However, of note, when more specimens are uncovered from formations of various age, further detailed examination of opaque patch patterns in well-preserved specimens is required to determine whether late Eocene to Holocene specimens and occurrences are truly of the same species.
Likely offshore marine.LE(all), KJ(all) � Parakrithella australis McKenzie, 1967 Various marine environments including shallow offshore marine, the intertidal zone, tide pools, coastal inlet channels and lagoons.

LE(all), KJ2
� Callistocythere puri McKenzie, 1967 Shallow marine environments including the intertidal zone and coastal estuaries not subjected to major salinity fluctuations, marginal marine areas, tide pools and coastal inlet channels.

KJ2, KJ3
� Loxoconcha trita McKenzie, 1967 Varying marine conditions; found in tide pools, coastal marine environments and coastal inlet channels but is more commonly confined to open marine conditions, tidal, and intertidal zones.

KJ(all)
� Mckenziartia portjacksonensis (McKenzie, 1967) Shallow, coastal marine palaeoenvironments, coastal inlet channels and lagoons.It also occurs in estuarine and shallow open marine environments and is able to tolerate significant salinity fluctuations.

LE(all), KJ(all)
Cletocythereis caudispinosa Chapman & Crespin, 1928 Mid-to outer continental shelf palaeoenvironments.LE2, LE3, LE4, KJ(all) (continued) 1995,2003), from the late Paleocene, Eocene (Eglington 2014), Oligocene (McKenzie et al. 1991) and Miocene (Whatley & Downing 1983, Neil 2006) of Victoria and the Holocene of the Bass Strait region (Yassini & Jones 1995).In the Oligocene of southeastern Australia, this species has been identified in offshore shelf palaeoenvironments (McKenzie et al. 1991).In the mid-Miocene, this species is conspicuous in middle to outer shelf palaeoenvironments (Whatley & Downing 1983, Warne 1987), with occurrences becoming less common in shallow marine palaeoenvironments (Warne 1988).Holocene specimens found in Bass Strait are associated with shallow, open marine environments (Yassini & Jones 1995).Guzel ( 2012) also recorded a very similar species (Neonesidea ex.gr.australis, Guzel 2012, p. 119) from the Late Cretaceous (Maastrichtian) of Western Australia.These Cretaceous and Cenozoic Neonesidea taxa, which have a distinctive, subovate carapace with the posterior extremity directly adjacent to the ventral margin, are here referred to as the 'australis species' group.This species group consists of Cretaceous and Cenozoic specimens predominantly from Australasia, and includes one new species described here: Neonesidea chapminuta sp.nov.The widespread nature of this species group in modern Australian marine waters is reflected by the occurrence of a different but similar species to N. australis, in tropical shallow seas of northern Australia (Whatley et al. 1996).The Australasian palaeobiogeography of this group attests to the ancient Gondwanan origins of this taxonomic clade.

Diagnosis
A notably small species for the genus with an elongate, subtriangular carapace, a lack of a tapered and upturned caudal process, the absence of a convex anterodorsal slope in right valves and distinct cardinal angles.

Etymology
In honour of an early Australian ostracod researcher, Frederick Chapman.

LE(all)
� Ponticocythereis militaris (Brady, 1866) Varied marine environments ranging from swash marks, the intertidal zone and shallow coastal marine to estuarine environments and sheltered embayments.

LE(all), KJ(all)
Trachyleberis thomsoni (Hornibrook, 1952) large/ robust form Marine palaeoenvironments on the outer continental shelf and upper continental slope, at approximately 100 m ocean depth.

Description
Seventy-three specimens (40 adults, 33 juveniles) were recovered.Neonesidea chapminuta is an unusually small species for the genus, elongate oval to subtriangular with a smooth outer surface.The maximum length is below the mid-height, and the maximum height is in the mid-third.The anterior margin is broadly and unevenly rounded, widest at mid-height, and with a straight anterodorsal slope.The posterior margin is narrowly rounded with the posterior extremity adjacent to the ventral margin.The dorsal margin is straight, with a prominent anterior cardinal angle situated slightly anterior of mid-length giving the overall carapace a dorsally pointed profile around mid-length (typical for the australis group of Neonesidea species).The anterodorsal slope is mostly straight in the RV and slightly convex in the LV, and the short posterodorsal slope is slightly convex in both the LV and RV.Ventral margin mostly straight with a slight oral concavity, which is more visible in interior view and in male specimens.The valve surface is smooth with no ornamentation, no visible eye tubercle and no visible subcentral tubercle.Inner lamella moderately wide, as typical for the genus, widest at the anterior and the posteroventral region, thinnest at the oral concavity and the posterodorsal region.Marginal pore canals are not visible.Muscle scars consist of eight wedge-shaped scars arranged in four close, sub-horizontal to diagonal rows (two per row) with the top row being slightly curved over the lower scars.Paired scars in each row are very close and appear almost fused in some instances.Hinge is smooth and adont.Sexual dimorphism weakly apparent, males being more elongate than females.

Remarks
Neonesidea chapminuta is morphologically similar to N. australis but is considerably smaller.This new species can be differentiated from N. chapmani by its shorter valves, less distinctive angle between the dorsal and posterodorsal margins, lack of distinctly convex RV anterodorsal slope, and by the absence of a tapered and upturned caudal process.Aside from being smaller, N. chapminuta can be differentiated from the very similar N. australis by its slightly narrower posterior margin, and more distinct anterior and posterior cardinal angles.This new taxon belongs to the 'australis species group' of Neonesidea, which typically occupy/occupied an offshore continental shelf habitat (e.g., Whatley & Downing 1983, Yassini & Jones 1995).

Diagnosis
A long, particularly robust species of Tasmanocypris with a pointed posterior, a broad inner lamella, and a low height compared to the length of the carapace for the genus.

Etymology
From the Latin term salaputium: squat.Named for its short height relative to carapace length.

Description
A total of 237 specimens (107 adults, 130 juveniles) were recovered.A species with a very large robust, thick, subtriangular shell.The maximum height is at the mid-point, and the maximum length is immediately below the mid-height.The dorsal margin is broadly and unevenly curved, and slightly pointed anterior to the mid-point (more prominent in left valves).The posterior half of the dorsal margin is mostly straight, in some cases with a very slight concavity.The anterior half of the dorsal margin is more evenly curved than the posterior; however, there is a very slight concavity present in RV.The ventral margin is mostly straight in lateral view, with a slight oral concavity visible in interior view.The anterior margin is evenly curved, and the anterior cardinal angle is not particularly prominent and not visible in external view, rather appearing as a smooth slope.The posterior margin slopes downwards towards the posteroventral margin and meets the flat ventral margin in a distinctive blunt/slightly rounded point.The outer surface is completely smooth.
Internal detail consists of a simple strongly adont hinge and simple normal pore canals unevenly scattered.The inner lamella is broad, especially in the anterior and posterior regions, thinner in the dorsal region and thinnest in the anterodorsal area.Muscle scars appear typical for paracypridines (Fig. 4L), with four vertically aligned adductor scars and two additional adductor scars behind the row.Division or suturing of adductor scars may be present in some specimens.

Remarks
Warne (2020) outlined several morphological species groups within Tasmanocypris.This species belongs to the 'eurylamella species group' of Tasmanocypris sensu lato, which includes the late Eocene Tasmanocypris latrobensis Eglington, 2006, and the late Oligocene Tasmanocypris eurylamella McKenzie et al., 1991.Taxa from the 'eurylamella species group' are also known from Holocene shallow marine environments and occupy continental shelf habitats with cool temperate to tropical marine climates (Warne 2020).
Tasmanocypris salaputia sp.nov. is in general, morphologically similar to the other members of the 'eurylamella species group', and to Tasmanocypris lochardi.It can be differentiated from T. latrobensis by its less pointed posterior, shorter height compared to carapace length, straighter ventral margin, and less concave anterodorsal margin in the left valves.Tasmanocypris salaputia sp.nov.can be differentiated from T. eurylamella by its straighter ventral margin, slightly more rounded posterior extremity, slightly less steeply angled dorsoventral margin and narrower ventral inner lamellae.It can be differentiated from T. lochardi by its more pointed posterior, less broadly rounded posterior and slightly more concave anterodorsal margin.

Remarks
Paracypris bradyi has been recorded from the Late Pleistocene of New South Wales (McKenzie & Pickett 1984), late Eocene of South Australia (McKenzie et al. 1991) and the Holocene of Victoria (McKenzie 1967, McKenzie et al. 1990, Yassini & Jones 1995) and New South Wales (Yassini & Jones 1987).Holocene specimens from this species have been found in beach swash marks (McKenzie 1967) and coastal inlet channels (Yassini & Jones 1987), and it is generally common in southern Australian coastal areas (McKenzie et al. 1990).Some fossil specimens have been identified from offshore marine facies (McKenzie et al. 1990), suggesting it is not restricted to coastal palaeoenvironments.

Remarks
The type species for Phlyctenophora Brady, 1880 is Phlyctenophora zealandica (Brady, 1880).In their review of some specimens described by Brady (1880), Puri & Hulings (1976, p. 256) commented that 'the specimen labelled by Brady as Phlyctenophora zealandica in the British Museum collection … may not represent Brady's [original published] concept of the species', and also commented that for this species 'the selection of a lectotype is deferred until living specimens are found in adequate quantity and described'.However, later in the same paper, Puri & Hulings (1976) figured the aforementioned specimen (plate 1, figs 17, 18) and indicated in the relevant plate description that it was the lectotype for Phlyctenophora zealandica Brady, 1880.Based on the discussion on p. 256 of Puri & Hulings (1976), this specimen derives from one of the original collection localities (Humboldt Bay, Papua at 37 fathoms) listed for P. zealandica by Brady (1880, p. 33).One might speculate that this designation of a lectotype for this species by Puri & Hulings (1976) involved an editing error.However, if this lectotype designation is accepted as valid, then the species Phlyctenophora zealandica appears to be a junior synonym of Phlyctenophora orientalis Brady, 1868, as per relevant taxonomic assessments by Whatley & Zhao (1987), Mostafawi (1992) and Wouters (1999).Consistent with this view, the morphological concept of the carapace for Phlyctenophora, as broadly accepted (e.g., McKenzie & Pickett 1984, Warne 2020), closely aligns with the carapace morphology of Phlyctenophora orientalis Brady, 1868.Phlyctenophora sp. (Fig. 5A)

Remarks
This form is similar to Phlyctenophora orientalis Brady, 1866 (see above remarks) known from ocean depths of 25-65 m (Whatley & Zhao 1987), but we have insufficient material (seven identified specimens, most not suitable for SEM imaging) to make a definitive species level identification.

Remarks
McDonald & Warne (2022) listed Cytheropteron praeantarcticum (Chapman, 1914) as a possible synonym of Oculocytheropteron microfornix Whatley & Downing, 1983.Based on a recent re-examination by us of the type material for the Chapman species, we now regard these taxa as separate species.Oculocytheropteron microfornix ranges from the late Eocene of New Zealand (Ayress 1995) to the late Oligocene (McKenzie et al. 1991, Eglington 2019), and Miocene (Whatley & Downing 1983, Warne 1987, McHenry 1996, Neil 2006) of Victoria.This species has been identified from offshore marine facies (McKenzie et al. 1991) and from continental shelf palaeoenvironments (Warne 1987), and more commonly in mid-to outer shelf palaeoenvironments (e.g., Whatley & Downing 1983).

Diagnosis
An Oculocytheropteron species characterized by a very long posteroventral margin adjacent to a broad inner lamella, resulting in a high posterior extremity.

Etymology
Named for the type locality of the species; the Jemmys Point Formation.

Description
A total of 169 specimens (106 adults, 63 juveniles) have been recovered.Oculocytheropteron jemmyensis sp.nov. is a thick-shelled species with a sub-rhomboidal to sub-ovate carapace.The dorsal margin is broadly and evenly arched with a small posterior concavity in RV, and in LV it is broadly arched with a concavity anterior to the mid-point and one posterior to the mid-point.The posterior margin begins from the end of the posterior concavity and angles towards the posterior point, which is a dull point, in some cases flattened in RV.From the posterior point, the distinctly long posteroventral margin curves broadly towards the mid-point of the ventral margin, before arching upwards toward the anterior.The ventral margin is then mostly obscured by the posteriorly pointed alar process.The anterior margin is unevenly curved and smooth.The marginal rim is thin and even along visible areas of the margin.The anterior cardinal angle is not prominent in external view, but broadly obtuse and slightly rounded in internal view.The posterior cardinal angle is prominent and obtuse in internal and external view.The surface detail consists of the wide, posteriorly pointed alar process, small circular and unevenly distributed punctae across the surface and a dense single line of punctae along the full length of the anterior edge of the alar process.The alar process is blunt and rounded at the end and extends to slightly past the ventral margin, terminating slightly posterior to the mid-length.Thin, low ribs are present along the surface but most prominent along the edges of the alar and running parallel to the dorsal marginal rim and behind/posterior to the alar process.A very small eyespot is present approximately even with the anterior cardinal angle.Merodont hinge with a mostly straight hinge bar and fine crenulation.Inner lamella wide along the anterior margin, not visible on the anteroventral margin, and distinctly broad along the posteroventral margin with a slight thinning in the centre of that section.Central muscle scars not distinct due to preservation.

Remarks
This species is morphologically most similar to Oculocytheropteron wilmablomae Yassini and Jones, 1995.The new species can be differentiated by its alar process being more blunt and less angled to the posterior, by the concavity present in some specimens behind the anterior cardinal angle, by its longer and more evenly rounded posteroventral margin, by the slightly smaller punctae, and by its relatively wider inner lamella.It is assigned to Oculocytheropteron rather than the closely related Cytheropteron due to the presence of an eyespot.A morphologically similar species listed here as Oculocytheropteron sp.cf.jemmyensis (Fig. 5C) also occurs within our studied fossil faunas, although the latter has a less broad posteroventral inner lamella.
The palaeoenvironment of this species is likely to be similar to that of other Oculocytheropteron species within the assemblage.Oculocytheropteron jemmyensis sp.nov. is co-preserved with Oculocytheropteron microfornix Whatley & Downing, 1983.The latter species is known from offshore continental shelf palaeoenvironments, most commonly from the mid-to outer shelf (Whatley & Downing 1983, Warne 1987, McKenzie et al. 1991).

Remarks
Cytheropteron parawellmani ranges from the late Oligocene (McKenzie et al. 1991) to the Miocene (Whatley & Downing 1983, Warne 1987, McHenry 1996) of Victoria.This species has been identified in assemblages from offshore marine facies (McKenzie et al. 1991) and from mid-to outer continental shelf palaeoenvironments (Whatley & Downing 1983, Warne 1987).McKenzie et al. (1991) listed the species as belonging to Oculocytheropteron rather than Cytheropteron.However, this generic reassignment would require the presence of eyespots, which are not clearly apparent on our specimens.

Remarks
Hartmann (1978) referred the holotype of Hemicytherura spinifera to a weaker calcified form of this species, i.e., Hemicytherura spinifera forma paucicalcerata.He also recognized a second form or subspecies Hemicytherura spinifera forma gravecalcerata.Since it includes the species' holotype, Hemicytherura spinifera forma paucicalcerata is more correctly referred to as Hemicytherura spinifera spinifera.However, we consider that the variation in ornament pattern between these two taxa (and not the variation in strength of carapace calcification) warrants separate species status (i.e., Hemicytherura spinifera and Hemicytherura gravecalcerata).Hemicytherura reeckmanni McKenzie et al., 1991, from the late Oligocene to the mid-Miocene of southeastern Australia (McKenzie et al. 1991, McHenry 1996) appears to be ancestral to Hemicytherura spinifera.All these taxa are here collectively referred to as the 'spinifera species group' of Hemicytherura and occupy/occupied nearshore to shallow offshore marine environments (Hartmann 1978, McKenzie et al. 1991).Extant Hemicytherura spinifera sensu stricto (aka H. spinifera forma paucicalcerata of Hartmann, 1978) has a subtropical distribution in Australian coastal waters (Hartmann 1978, Yassini & Jones 1995).

Remarks
Semicytherura sp. 2 was previously figured but not described by McHenry (1996), from mid-Miocene strata in South Australia where it occurred in a marine continental shelf palaeoenvironment.A characteristic feature of this species is the horizontally to slightly obliquely aligned punctae associated with similarly aligned ridges on the carapace surface.

Remarks
Neobuntonia foveata has been identified previously from the Pleistocene of Victoria (McKenzie et al. 1990).Specimens of this species have been found in assemblages reflective of warm shallow marine palaeoenvironments (McKenzie et al. 1990) and it has been noted that Pleistocene occurrences of the species could be indicative of ocean temperatures 3-5 � C higher than today (Warne 2005).The type specimen imaged by McKenzie et al. (1990) appears to be broken so it is difficult to definitively confirm the species identification; however, the new material does appear to match the original description.

Remarks
Compared to Caudites sp.herein, Caudites yambaensis Hartmann, 1981, is less elongate, possesses a more arched shape, and has a lower caudal process situated near the ventral margin.Holocene species of Caudites have been identified in shallow coastal marine environments and estuaries (Yassini & Jones 1995).Hartmann (1981) suggested that this genus was characteristic of warmer water coastal environments, in tropical to marginal subtropical regions.

Remarks
We consider that the shallow marine species Bradleya bassbasinensis possibly belongs to the same clade as deep-sea species of Harleya Jellinek & Swanson, 2003, illustrated by Jellinek & Swanson (2003) and Brandão & P€ aplow (2011), based on its elongate box-like carapace in lateral view with the height at the anterior and posterior cardinal angles being almost equal; by its swollen posterodorsal quadrant of the carapace; and by the almost straight and truncated appearance of the posterior margin.However, the ornamental characteristics of Harleya described by Jellinek & Swanson (2003) are different from that represented on B. bassbasinensis, in particular the strong reticulate ornament of the specimen illustrated here, compared to the fine ornament of deep-sea species of Harleya.Consequently, we have provisionally assigned this species to Bradleya sensu lato pending a morphological review of deep-sea, and possible shallow marine species groups that may be attributed to Harleya.Bradleya bassbasinensis differs from many species of Bradleya and Quasibradleya Benson, 1972, by possessing a less prominent median ridge and posterodorsal loop (see also Yassini & Jones 1995, fig. 434), straight and relatively long posterodorsal slope, with the posterior caudal process and posterior extremity situated immediately adjacent to the ventral margin.Thaerocythere Hazel, 1967 species are smaller and have arched dorsal margins compared to the more or less straight dorsal margin in Bradleya bassbasinensis.The ornament of Poseidonamicus Benson, 1972 species generally includes vertically oriented ridges that are not apparent on B. bassbasinensis.Yassini & Jones (1995) recorded Holocene specimens of Harleya bassbasinensis from shallow marine environments of Bass Strait, southeastern Australia, with the type locality being at 58 m water depth.Whatley & Downing, 1983 (Fig. 6G-I 10A-C.

Remarks
A species of Bradleya that has a similar adult ornament (Fig. 5P) to the species we identify as Bradleya bassbasinensis, although the two species differ in the shape of the posterior margin, and position of the posterior extremity (adjacent to the ventral margin in B. bassbasinensis, higher and nearer to mid-height in Bradleya sp.).We do not exclude the possibility that some specimens we have identified as Bradleya sp. are in fact juvenile specimens of B. bassbasinensis.

Remarks
A Krithe species with marked sexual dimorphism, with males being much more elongate than females.It has an overall carapace shape similar to Krithe postcircularis McKenzie, Reyment & Reyment, 1993, from the late Eocene of southeastern Australia, except the informal species has a more rounded and truncated posterior margin.Also similar to the extant species Krithe dilata Ayress, Burrows, Passlow & Whatley, 1999, from the eastern Australian continental slope (min depth 355 m), although the fossil species is slightly more rotund.Krithe nitida Whatley and Downing, 1983, originally described from the mid-Miocene of southeastern Australia, has a less rotund adult female carapace shape compared to the new form.

Remarks
Parakrithella eggeri (Chapman, 1914) from the Neogene of southeastern Australia has a more elongate and less rotund outline in lateral view compared to Parakrithella australis.Parakrithella australis is known from the Late Pleistocene of New South Wales (McKenzie & Pickett 1984), Late Miocene of southeastern Australia (McDonald & Warne 2022), and from Holocene environments from Victoria (McKenzie 1967), the Bass Strait (Neil 2000) and New South Wales (Yassini & Jones 1987, 1995).Holocene specimens have been found in coastal tide pools (McKenzie 1967) and coastal inlet channels (Yassini & Jones 1987).It has also been located in Port Phillip Bay and in estuarine environments, where it is very common (Yassini & Jones 1995).Yassini & Jones (1995) noted that it is mostly restricted to the marine intertidal zone and in lagoonal environments.Fossil specimens have been identified in shallow offshore marine strata (McDonald & Warne 2022).

Remarks
Extant Callistocythere puri specimens are known from coastal environments of Victoria (McKenzie 1967, McKenzie et al. 1990) and New South Wales (Yassini & Jones 1987, 1995), and fossil forms are known from Pliocene sediments from the Bass Strait hinterland (Warne & Soutar 2012).Holocene specimens are abundant in the intertidal zone and coastal estuarine environments that are not subjected to large salinity fluctuations (McKenzie 1967, McKenzie et al. 1990, Yassini & Jones 1995).Fossil specimens have also been identified within assemblages indicative of marginal marine palaeoenvironments (Warne & Soutar 2012).In summary, this species is abundant in shallow, marginal and open marine environments and has also been found in the intertidal zone on algal mats, in rock pools (Warne & Soutar 2012) and in coastal inlet channels (Yassini & Jones 1987).

Remarks
Mio-Pliocene specimens of Callistocythere ventroalata from the Jemmys Point Formation appear to have the same surface ornamentation as the Holocene type specimens described by Yassini & Jones (1995).However, our illustrations of this species indicate the presence of LV terminal hinge elements reminiscent of some species in Hemicytheridea (Kingma, 1948), and a faint surface ornament pattern with some similarities to the stronger surface ornament of species of Vandiemencythere Ayress & Warne, 1993 (see discussion by Warne 1996).Consequently, our identification of this species as belonging to Callistocythere s.s. is tentative and may be reviewed if more specimens are recovered.Yassini & Jones (1995) recorded Holocene specimens of this species as occurring in open shallow marine environments of southeastern Australia, and Warne & Soutar (2012) inferred a similar palaeoenvironment for specimens from Pliocene strata in southeastern Australia.

Locality, unit and age
Kalimna Jetty, Kalimna, Victoria (37.878 � S 147.955 � E, Datum WGS84), coastal cliff exposure layers KJ1-KJ3, lower Jemmys Point Formation, Early Pliocene (Zanclean; Kalimnan).McKenzie (1967) recorded Holocene specimens of this species from swash marks in Port Phillip Bay, Victoria.Yassini & Jones (1987, 1995) recorded Holocene specimens of this species from the subtidal zone and being common in open coastal embayments of New South Wales, Australia, and from Holocene deposits of the Bermagui Shelf of southeastern Australia.

Remarks
Callistocythere sp.appears to have some similarities in surface ornamentation to Leptocythere hartmanni (McKenzie, 1967) and Callistocythere mchenryi McDonald & Warne, 2022.Callistocythere sp. has distinctive nodes on the valve surface, has larger and more distinctive punctae, and does not have the same reticulation as L. hartmanni.Callistocythere mchenryi has similar node placements but is smooth between the nodes and lacks the irregularly placed muri and punctae of Callistocythere sp.
Extant Callistocythere species are widely distributed in coastal waters and in warm to temperate shelf seas around Australia including in the intertidal zone, coastal lagoons and estuarine environments (Yassini & Jones 1995, McHenry 1996, Neil 2000).Within the fossil record, the genus is often considered a shallow marine indicator (Yassini & Jones 1995, McHenry 1996, Neil 2000. McDonald & Warne 2022).

Remarks
Copytus posterosulcus is an extant species known to exist in the Gulf of Carpentaria (Yassini et al. 1993) and southeastern Australia (Yassini & Jones 1995).Extant specimens of this species occur in the intertidal zone, inner shelf environments and in Bass Strait (Yassini & Jones 1995).

Remarks
The shape and ornament of this species is very similar to the type specimen of Parakeijia thomi illustrated by Yassini & Mikulandra (1989), except the specimen illustrated here has a more subdued ornament, hence the surface ridge pattern is less distinctive.Living specimens of Keijia thomi inhabit temperate coastal lagoons of southeastern Australia.

Remarks
Parakeijia notoreticularis is known from the mid-Miocene to Early Pliocene (Warne 1987, McHenry 1996, McDonald & Warne 2022) of southeastern Australia.This species has been identified in fossil associations referable to inner continental shelf marine palaeoenvironments (Warne 1987)

Remarks
Dumontina lauta appears to have an extraordinary latitudinal range along the east coast of Australia, suggesting that its dispersal has been strongly influenced by warm flows of the East Australian Current.It is known from modern tropical marine environments of northern Australia (Brady 1880, Hartmann 1981, Warne et al. 2006), modern temperate coastal marine environments of New South Wales (Yassini & Jones 1987, 1995) and Bass Strait (Yassini & Jones 1995, Neil 2000), and from 'warm water' mid-Pleistocene deposits of Victoria (McKenzie et al. 1990).The earliest record of an ancestral species has been noted by Warne (1987, 1989, Neil 1994) from warm-water mid-Miocene marine palaeoenvironments of southeastern Australia.The mid-Miocene record accords with the Warne & Whatley (2016) interpretation of the mid-Miocene inception or strengthening of the East Australian Current influence on southeast Australian marine realms.Extant specimens have been identified in shallow coastal marine environments (Warne et al. 2006), at ocean depths of approximately 10-14 m (Brady 1880) and in coastal inlet channels (Yassini & Jones 1987).This species also occurs in open estuaries, sheltered marine embayments and in intertidal to inner shelf marine environments (Yassini & Jones 1995).The specimens illustrated here (Fig. 9J-L) display both thickening of muri and some surface abrasion, reducing the prominence of surface ornament.

Diagnosis
Philoneptunus plutonis sp.nov. is a small species for the genus, subtriangular, and characterized by fine punctae covering the external surface; a weak subcentral tubercle, a wide anterior rim, and anterior and posterior marginal spines.

Etymology
The Latin name for Pluto, brother of Neptune and god of the underworld, in reference to the genus name and the deep marine environment of the species.

Description
A total of 260 specimens (158 adults, 102 juveniles) have been recovered.Philoneptunus plutonis sp.nov. is small for the genus (most adults of other similar species are over 1 mm in length on average (Jellinek & Swanson 2003).It is a thick-shelled Philoneptunus species, subtriangular in lateral view, tapering posteriorly.The maximum height is at the anterior cardinal angle and the maximum length is immediately below mid-height.The anterior margin is broadly and evenly rounded in females and broadly rounded with an anterodorsal concavity in males.An average of 10-12 short, rounded marginal spines are present on the anterior margin, most prominent in the anteroventral region.The dorsal margin is straight in internal view but partially obstructed in the posterior half by the dorsal ridge.The anterior cardinal angle is visible in the interior view.A weakly developed eye tubercle is present.The ventral margin is mostly straight with a weak oral concavity.The posterior cardinal angle is prominent in internal view.The dorsal and ventral margins taper to the pointed posterior, the margin of which has a concavity behind the posterior cardinal angle/end of dorsal ridge, an irregularly and acutely curved end that terminates in up to nine small, generally blunt spines, which are concentrated at the posteroventral region and are more visible in internal view.The anterior has a wide marginal rim, which extends from the eye spot to the beginning of the ventral ridge.The marginal rim has small aligned rectangular reticulation.A weak subcentral tubercle is present at mid-height, posterior to the eye tubercle.Fine punctae densely cover the surface of the valve, but fewer are present on the subcentral tubercle.Punctae align parallel along the ventral ridge but are not present on the anterior rim.The dorsal ridge is irregular, extending to the posterior cardinal angle, ending in a protuberance, which is more prominent in female specimens.
Internal features are typical for the genus.Internal muscle scars consist of a vertical row of four weakly joined adductors and a trachyleberid V-shaped frontal scar.Marginal pore canals simple and straight.Hinge is pseudoentomodont.Wide inner lamella, broadest anteriorly and posteroventrally.Thick line of concrescence and selvage.Strongly sexually dimorphic; males more elongate and have a more prominent anterodorsal marginal concavity, females are broader and have a more defined dorsal ridge terminating in a spine.

Remarks
Philoneptunus plutonis sp.nov. is morphologically similar to two other species within this genus; Philoneptunus planaltus (Hornibrook, 1952) and Philoneptunus praeplanaltus Whatley et al., 1992.It is differentiated from P. planaltus by the presence of a visible subcentral tubercle and by surface punctae being more numerous and smaller; the posterior spines being more developed and the marginal rim being slightly broader.Philoneptunus plutonis sp.nov. is also smaller and subtriangular, compared to the subrectangular shape of P. planaltus (Hornibrook, 1952).
Philoneptunus plutonis sp.nov. is differentiated from P. praeplanaltus Whatley et al., 1992 by the presence of a visible subcentral tubercle, the dorsal margin being less obscured by the surface ornamentation than it is in P. praeplanaltus, the absence of backward-facing spines on the dorsal rib and a less developed median rib.The carapace is more triangular, tapering posteriorly, and the eye tubercle, anterior cardinal angle and anterodorsal margin are less prominent than in P. praeplanaltus.The surface punctae appear more numerous in Philoneptunus plutonis sp.nov., but this difference is minor.The plate images provided by Whatley et al. (1992) that illustrate P. praeplanaltus appear to have been incorrectly ordered and labelled, with plate 3 being displayed first and plate 1 displayed last.
Philoneptunus plutonis sp.nov. is also superficially similar to some shallow marine species of Margocythere McKenzie et al., 1991, andCletocythereis Swain, 1963.Philoneptunus plutonis is not assigned to Margocythere because it lacks the characteristic rugged ornament of species in this genus (e.g., Margocythere aspreta McKenzie et al., 1991), has a pseudoentomodont hinge rather than hemiamphidont hinge, differs in the muscle scar pattern, and has a more subtriangular rather than subrectangular shape.There are some similarities between P. plutonis and Cletocythereis curta McKenzie, 1967, in the carapace shape, positioning of spines and overall morphology, although the former lacks the strong reticulate ornament of the latter.
Extant Philoneptunus species are endemic to oceans surrounding eastern Australia and New Zealand, and have been noted to exist in offshore marine environments ranging from the continental shelf to abyssal ocean depths (Whatley et al. 1992), with most species occurring in deeper environments.The bathymetric ranges for some species are listed below.Mazzini (2005) interpreted 'Cythereis' planalta sensu Swanson, 1979, [¼ P. gravezia (Hornibrook, 1952)] to have existed in ocean depths of 182-750 m.Jellinek & Swanson (2003) recorded ocean depths for extant species within the genus as follows: Philoneptunus paeminosus Whatley et al., 1992, between 562 and 955 m, Philoneptunus provocator Jellinek &Swanson, 2003, andPhiloneptunus neesi Jellinek &Swanson, 2003, both between 560 and 958 m, and Philoneptunus gigas Jellinek & Swanson, 2003, between 562 and 1681 m.Our record of a late Neogene species of Philoneptunus in a shallow marine palaeoenvironmental setting suggests migration from deeper sea realms on upwelling currents.Of note, Philoneptunus species were not recorded within the Miocene deep-sea faunas of the offshore Gippsland Basin by Warne & Whatley (1994).Records of this genus, thus, first appear in the Gippsland Basin during the Early Pliocene.

Remarks
This species occurs in fossil marine assemblages interpreted to have occurred at around 100 m ocean depth (Ayress 1993a), on the outer continental shelf and the upper continental slope (Ayress 1995).Adult specimens occur as either a 'large form' or 'small form', with the 'small form' being approximately half the length of the 'large form'.
Trachyleberis thomsoni (large form) is known from the late Eocene to Miocene of New Zealand (Ayress 1993a(Ayress , 1995) ) and late Paleocene to early Eocene of Victoria (Eglington 2014).
Trachyleberis thomsoni ('small form') is known from the late Eocene to Miocene of New Zealand (Ayress 1993a(Ayress , 1995) ) and the late Paleocene to earliest Eocene of Victoria (Eglington 2006).The dwarf form of the species [referred to as Trachyleberis thomsoni?by Eglington (2006Eglington ( , 2014))] commonly co-occurs in assemblages with the 'large form', which is more robust and is inferred to have a similar palaeoenvironmental range.

Remarks
A single adult carapace of this species, which was opened for internal imaging, was found during this study.This species is assigned to Trachyleberididae and with some significant uncertainty to Trachyleberis.Although the ornamentation of this species is similar to that of Penyella Neale, 1974, Rugocythereis Dingle, Lord & Boomer, 1990, and Legitimocythere Coles & Whatley, 1989, the presence of a well-developed eye tubercle precludes our specimen from belonging to these deep marine genera.Acanthocythereis Howe, 1963, andTrachyleberis Brady, 1898 both also have similar ornamentation and eye tubercles; however, the new specimen is too poorly preserved due to secondary surface calcification, which prevents a definitive generic identification.Glencoeleberis Jellinek & Swanson, 2003 shares several characteristics with our specimen, such as the spinose posterior and anterior margin, subtriangular carapace shape, and the presence of a well-developed eye tubercle and sub-central tubercle, but the diagnostic secondary surface ornamentation (irregular meshwork of faint striae) for Glencoeleberis species is not visible.

Remarks
Foveoleberis minutissima is known from the late Eocene to Early Miocene of New Zealand (Ayress 1993(Ayress , 1995)), and the late Eocene (McKenzie et al. 1993), late Oligocene (McKenzie et al. 1991, Eglington 2019) and Miocene (Whatley & Downing 1983, Warne 1987, Neil 2006) of Victoria (McKenzie 1974).This species has been identified in assemblages typical of offshore mid-to outer continental shelf palaeoenvironments (Whatley & Downing 1983, Warne 1987, McKenzie et al. 1991).McKenzie et al. (1993) also suggested that it was characteristic of warm marine palaeoenvironments.Extant specimens occur in shallow open marine environments on the inner and middle continental shelf (Yassini & Jones 1995).Chapman's (1926) original type specimen of this species in Museums Victoria is of fragmentary shell material.The species has previously been assigned to both Foveoleberis and Uroleberis Triebel, 1958.We have assigned it to Foveoleberis due to the presence of a crenulated median hinge and fine pitted surface ornamentation, which is consistent for the genus (Malz 1980, McKenzie et al. 1991)

Remarks
Cytherella paranitida is known from the middle Eocene to Holocene of New Zealand (Ayress 1993(Ayress , 1995) ) and the Early to mid-Miocene of Victoria (Whatley & Downing 1983, Warne 1987, Neil 2006).This species was identified by Whatley & Downing (1983) and Warne (1987) in assemblages characteristic of mid-to outer shelf marine palaeoenvironments and by Neil (2006) in assemblages indicative of shallow marine palaeoenvironments.

Remarks
A similarly shaped cytherellid species, Cytherella tananita (Swanson et al., 2005) from the Challenger and Campbell plateaus offshore from New Zealand, which has reverse cytherellid hinge elements (left valve with hinge groove, right valve with hinge ridge) was designated by Swanson et al. (2005) as the type species for their new genus Inversacytherella.However, we consider that Cytherella lata from the Jemmys Point Formation and the Holocene Cytherella tananita from the SW Pacific Ocean are probably closely related from a phylogenetic perspective based on carapace shape.Thus, we consider Inversacytherella to be a synonym of Cytherella, and we regard these taxa as belonging to the informal 'lata species group' of Cytherella.The new specimens of Cytherella lata are slightly more elongate than the lectotype for this species designated by Puri & Hulings (1976); however, this difference might be explained as intraspecific variation.Cytherella lata is known from the Pliocene of southeastern Australia (Warne & Soutar 2012) and Holocene of Bass Strait (Yassini & Jones 1995, Neil 2000).Yassini & Jones (1995) noted that the species is exclusively associated with upper bathyal and lower neritic assemblages in the eastern part of Bass Strait (near the Bass Canyon upwelling), and along the southeastern Australian continental shelf below 80 m ocean depth.Specimens have also been identified on the outer shelf below 80 m ocean depth by Neil (2000) and have been recorded at water depths up to 1225 m by Brady (1880).

Remarks
Cytherelloidea auricula is known from the mid-Miocene and Early Pliocene (Chapman 1914, Warne 1993) of southeastern Australia.This species has been interpreted to have existed in mid-to outer continental shelf palaeoenvironments (Warne 1993).

Early Pliocene upwelling via the Bass Canyon
The Lakes Entrance assemblages appear to be largely composed of autochthonous species, with almost all species represented by adults and juvenile specimens of various growth stages, although early-stage juveniles are less well represented.The population-age structures for these assemblages suggest a low to moderate energy fossil 'biocoenosis' sensu Whatley (1988), and thus reflect the original depositional environment for host strata [NB.see discussion on the appropriateness of Whatley's (1988) use of the term biocoenosis by Boomer et al. (2003)].At the Lakes Entrance (Ferndale Parade) locations, where the deep-sea species P. plutonis is found, the ostracod assemblages include the presence of some polished specimens that suggest the gentle agitation of these microscopic 'shells', and preservation under conditions of low to moderate energy, and low sedimentation rates, within condensed time-averaged fossil accumulations.
Collectively, the assemblages from the Lakes Entrance locality (adjacent to the end of Ferndale Parade) are dominated by the mid-to outer shelf species Bradleya praemckenziei Whatley & Downing, 1983 (16.79% of the overall specimens in the assemblages), and Cytheropteron parawellmani Whatley & Downing, 1983 (8.38%).Other identified species within these assemblages that make up more than 5% of the population include autochthonous populations of Tasmanocypris lochardi Warne, 2022 (7.08%), which has been considered indicative of inner to midshelf environments (Warne 2022), and Philoneptunus plutonis sp.nov.(6.71%), a likely deep-sea taxon that probably immigrated on upwelling currents onto the palaeo-Gippsland continental shelf (Gallagher et al. 2003) [the known depth range of Quaternary and modern species of the genus is 131-3658 m (Whatley et al. 1992, Jellinek & Swanson 2003, Mazzini 2005)].Also present is the offshore marine species Cytherella lata Brady, 1880 (2.46%).Overall, the dominant ostracod faunal elements in this assemblage suggest a midto outer continental shelf palaeoenvironment, with 46.29% of the population characteristic of mid-to outer shelf palaeoenvironments, 27.33% of shallow offshore neritic palaeoenvironments and 18.67% of shallow nearshore palaeoenvironments (Tables 2-4).This mixture of shelf and deeper marine taxa is consistent with persistent coastal upwelling onto a continental shelf setting.These cool upwelling currents were likely funnelled onto the temperate Gippsland continental shelf via the palaeo-Bass Canyon on the adjacent southeastern Australian continental slope (Bernecker et al. 1997, Mitchell et al. 2007).

Adaptation of deep shelf clades to shallow marine realms
Within the 'warm' mid-Miocene waters of southeastern Australia, Neonesidea australis was predominately a deep offshore shelf taxon (Whatley & Downing 1983, Warne 1988).Extant specimens attributed to this species occur abundantly in shallow open marine environments of Bass Strait (Yassini & Jones, 1995).Earlier Neogene evidence of Neonesidea australis cooccurring commonly with shallow shelf taxa is apparent within the Lakes Entrance (Ferndale Parade) faunas of the Jemmys Point Formation, suggesting an ecological shift from deeper to shallower shelf conditions in southeastern Australia occurred sometime during the late Miocene to Pliocene transition.This ecological shift was perhaps facilitated by the upwelling of cool deep oceanic waters onto the Gippsland continental shelf.

Transition to nearshore palaeoenvironments
Overall, the Kalimna Jetty ostracod assemblage suggests palaeoenvironmental conditions were markedly different from those for the Lakes Entrance assemblages.Two dominant fossil species are the coastal to shallow neritic Ponticocythereis militaris (Brady, 1866) (16.89% of the population) and Actinocythereis tetrica (Brady, 1880) (13.50%).Also present in significant numbers is the neritic Tasmanocypris lochardi Warne, 2020 (13.28%).The ostracod population of the Kalimna Jetty fauna consists of 39.06% shallow nearshore species and 32.11% shallow offshore species, suggesting the assemblage is characteristic of shallower water conditions compared to the Lakes Entrance assemblages, and was not influenced by upwelling currents.However, not all species are associated with shallower waters; 25.44% of the population has offshore shelf affinities, with several prominent species being shared with the ostracod faunas from the Lakes Entrance locality (e.g., Oculocytheropteron microfornix (Whatley & Downing, 1983), Oculocytheropteron jemmyensis sp.nov., Cytheropteron parawellmani Whatley & Downing, 1983 and Bradleya praemckenziei Whatley & Downing, 1983).These occurrences possibly reflect adaptation to shallower marine conditions.The increased proportions of shallow and nearshore taxa, such as Callistocythere spp.within Kalimna Jetty sediments exemplifies the occurrence of quite shallow marine conditions.Also of note, the euryhaline species Mckenziartia portjacksonensis is present in the Kalimna Jetty fauna.
The ostracod assemblage from the Kalimna Jetty outcrop is also primarily composed of autochthonous species, with a Type A (low-energy) to Type B (highenergy) population-age structure (sensu Whatley 1988).This suggests a moderate-energy depositional palaeoenvironment with ostracod populations having been preserved in or near their original life environment.

Conclusions
The ostracod taxa present in the Lower Pliocene Jemmys Point Formation, extracted from five stratigraphic intervals from two localities in the Lakes Entrance-Kalimna district of East Gippsland, Victoria, evidence a diverse fossil fauna that includes four new species.Overall, the ostracod assemblages indicate a marked palaeoenvironmental transition during the Early Pliocene from offshore shelf to nearshore shelf conditions.It is argued that a strong and persistent upwelling current prevailed during the deposition of upper Cheltenhamian strata near Ferndale Parade, Lakes Entrance, which facilitated the migration of a deep-sea marine species of Philoneptunus onto the continental shelf.Further, this oceanographic process may have led to the adaptation of some deep shelf taxa to shallow cool temperate marine environments of southeastern Australia and points to an unusual evolutionary process that has contributed to present Bass Strait ostracod biodiversity.

Fig. 1 .
Fig. 1.Locality details.A, Map showing location of the two study localities (yellow pins) (Google Earth 2022).B, Map of Victoria showing location of the Gippsland Basin (in green) and approximate area of Fig. 1A (red box).

Table 1 )
indicate that the dated shells from these Jemmys Point Formation locations range in mean age from 3.966 to 3.234 Ma.Four of the five analyses yielded an Early Pliocene mean age, although the minimum and maximum age records, taken as whole, indicate a broad possible age range from the Early to Late Pliocene.The single mean age result from the Kalimna Jetty location suggests an Early Pliocene age consistent with planktonic foraminifera data

Table 1 .
Results of Sr radioisotope dating on Jemmys Point Formation shell samples, showing the mean age based on the LOESS Sr isotope lookup table (McArthur et al. 2020) and the age range based on 2r error calculations.

Table 2 .
Total number of adult and juvenile specimens of each identified ostracod species from the Lakes Entrance/Ferndale Parade locality.

Table 3 .
Total number of adult and juvenile specimens of each identified ostracod species from the Kalimna Jetty locality.

Table 4 .
Palaeoenvironmental ranges of identified species from the Jemmys Point Formation localities.Extant species are identified with ' � '.
(McDonald & Warne 2022, McDonald & Warne 2022has some similarities with Debissonia sp. 1 from the Upper Miocene Bookpurnong Formation in the Murray Basin(McDonald & Warne 2022).However, the Jemmys Point Formation species can be differentiated by possessing less raised muri.Further, for the Bookpurnong Formation species, some muri are aligned to form multiple distinct ridges.Debissonia species are known from upper Oligocene and Upper Miocene strata from southeastern Australia in assemblages reflective of offshore marine palaeoenvironments(McKenzie et al.  1991, McDonald & Warne 2022).