Overview of Recent and Holocene ostracods (Crustacea) from brackish and marine environments of Portugal

An extensive overview of Recent and Holocene ostracods from brackish and marine environments of Portugal is presented for the first time. 178 species belonging to 75 genera have been found and all are listed and illustrated with SEM images. From those species only 30 were found alive, most of them living in marginal-marine environments. Some comments on the 30 species found alive and a summary of main results are also presented. The data come from unpublished notes, reports of several research projects, observations on Recent ostracods in sediments from different estuaries of the western coast of Portugal and from the western Algarve continental shelf and slope, Masters theses and published papers.

shelf and slope (south Portugal), Masters degree theses and published papers. We consider here only the papers that have illustrations of the mentioned ostracods, or whose study material has been identified by the authors (Cearreta et al., 2003;Cabral et al., 2006Cabral et al., , 2011aLoureiro et al., 2009;Lord et al., 2011). All the unpublished theses were supervised by MCC in the Department of Geology, Faculty of Sciences, University of Lisbon and are archived and accessible in the Central Library of the Faculty of Sciences and in the Library of the Department of Geology.
The taxa have been identified only on the basis of carapaces without soft parts. Most of the Recent marine taxa, from the continental shelf or slope and from the tidal flats of the lower part of the estuaries, were found in fine-grained sediments, as separate valves, therefore limiting knowledge of where they really live today in the areas where they have been found. The material from the continental shelf and slope was frequently abundant, well preserved and represented by several ontogenic stages suggesting, in this case, that it was in situ. The material from the tidal flats was generally represented by rare valves of each species, frequently worn.
The brackish forms from the tidal marshes were generally collected in muddy sediment, and most of them were found alive, as indicated in the list. Only a few brackish forms from the tidal marshes were collected in fine sand or silty sand substrates. The brackish/marine forms from rock tidal pools and from the transect along the Laje River were collected both on algae and on sandy substrate. The marine forms from the continental shelf and slope were collected with a Smith-McIntyre (SMT) grab, in fine sediment patches (sand fraction generally <50 %). Forms were identified as alive when containing the soft parts (appendages) and pink staining due to Rose Bengal. The material from the tidal marshes was collected in two different seasons, generally in autumn and spring, very rarely at the beginning of winter and of summer; the material from the continental shelf and slope was collected during winter (January 2008) and spring (June 2008). Salinity and temperature values from tidal flat, low and high marsh sampling points were measured at low tide in the interstitial sediment water. The records were collected up to May 2012.
The taxonomy follows Horne et al. (2002). For the identification of most of the species, Athersuch et al. (1989)  Mira River -2 transects in the lower estuary (PMF and MAS), 2 transects in the mid-estuary (CBR and FLP).
Material also comes from the continental shelf and slope of western Algarve (south Portugal), between Sagres and Faro -9 sites in the continental shelf (1, 3, 5, 6, 8, 9, 12, 13 and 14) ranging in depth from -58 to -125 m and 2 sites in the continental slope (11 and 23), respectively at c. -220 m and c. -500 m deep.
Holocene material comes from several boreholes located in coastal lagoons or estuaries (Fig. 3). From north to south: Pederneira lagoon, west Portugal -2 long boreholes, both in the Recent alluvial plain of Alcoa River, 1 in the inner ancient lagoon (S2), another in the middle ancient lagoon (S3). Sizandro estuary/lagoon, west Portugal -1 long borehole in the alluvial plain of Sizandro River, around 10 km from coast (RS06_1). Tejo estuary -1 long borehole in Lisboa central urban area (esteiro da Baixa), Praça do Comércio (PC), and a 4 m core from a marsh area in Seixal bay (DWK2). Melides lagoon, SW Portugal -2 long boreholes, one in the alluvial plain of the Recent lagoon (MIGM), another in the sand barrier (MB). Santo André lagoon, SW Portugal -1 long borehole in the alluvial plain of the Recent lagoon (LSA).

lIst oF bracKIsh and MarIne ostracoda Found In Portugal
Systematics according to Horne et al. (2002). Identifications based primarily on Athersuch et al. (1989) and Bonaduce et al. (1976). note that primary author sources for individual species have been consulted but, for brevity, are not all listed in the References. Note: Includes all records, both live forms and dead carapaces/ valves. The localities (generally estuaries) where the Recent forms occurred are ordered from north to south; the localities where the Holocene forms occurred are ordered alphabetically. Species which are referred as cf. compare fairly closely with known species (they present almost all the characteristics of the species, but differ in one or two details, frequently because they are either worn or juveniles); species referred as aff. are probably new, but present some similarities with existing species.  1866 Family cytherellidae Sars, 1866 Genus Cytherella Jones, 1849 Cytherella alvearium Bonaduce, Ciampo & Masoli, 1976 -continental shelf and slope (Pl. 1, fig. 2) Cytherella robusta Colalongo & Pasini, 1980 -continental fig. 19)    Sagmatocythere multifora (norman, 1865) -continental shelf and slope, Holocene Lisboa (Pl. 6, fig. 13   Superfamily terrestricytheroidea Schornikov, 1969 Family terrestricytheridae Schornikov, 1969 Genus  A marine/marine to slightly brackish littoral species known from the Mediterranean to western Europe, found in France (Yassini, 1969, as Basslerites berchoni (Brady, 1870) and England (J. Whittaker, pers. comm.). In France, Arcachon Bay, it lives at depths of 2-8 m and salinity of 27 ‰ (Yassini, 1969). In Portugal found alive in the tidal flat of lower and mid-Mira estuary, in autumn and spring conditions (approximate salinity range of 32.1-33.8 ‰ and temperature 16.3-16.8 °C, in sediment interstitial water); also found alive in sites 3 (96.5 m depth) and 5 (94.0 m depth), in western Algarve continental shelf, in spring conditions.
Callistocythere badia (norman, 1862) A marine littoral species known from the Mediterranean to western Europe (Athersuch et al., 1989). In Portugal found alive on green and red algae, in an intertidal rockpool near Laje River mouth, Santo Amaro de Oeiras beach, in spring conditions (approximate salinity 36.2 ‰ and temperature 29.4 °C, at low tide).
Callistocythere murrayi Whittaker, 1978 A brackish species (1-8 ‰ at the type locality - Athersuch et al., 1989) known in western Europe, in British Isles and France (Chait et al., 1998). In Portugal found alive from the tidal flat to the low marsh in the lower Minho, mid Lima and lower Tejo estuaries, in autumn and spring conditions (approximate salinity range of 21.0-33.1 ‰ and temperature 12.4-18.5 °C, in sediment interstitial water).
Cyprideis torosa (Jones, 1850) A common and widespread highly euryhaline species, from almost freshwater to over 60 ‰, known in Europe (as far north as Iceland), Asia, Mediterranean region, Central Africa (Athersuch et al., 1989). In Portugal found alive from the tidal flat to the high marsh in the lower Tejo and lower Sado estuaries, in autumn/ winter and spring/summer conditions (approximate salinity range of 19.0-34.1 ‰ and temperature 13.8-21.7 °C, in sediment interstitial water). It seems to prefer very large estuaries, with almost lagoonal dynamics. no noded forms have been found until now.
Cytherois fischeri (Sars, 1866) A common and widespread brackish species, tolerating salinities from 4-35 ‰, known in the Mediterranean, western Europe, to Scandinavia in the north (Athersuch et al., 1989) and Morocco in the south (nachite et al., 2010). In Portugal found alive from the tidal flat to the lower part of the low marsh (much more abundant on the tidal flat) in the lower Minho, lower Tejo, lower Sado and lower Mira estuaries, in autumn/winter and spring conditions (approximate salinity range of 10.3-37.0‰ and temperature 13.7-19.7 °C, in sediment interstitial water).
Cytherois cf. stephanidesi Klie, 1938 A brackish species found associated with algae and fine sediment, in salinities of 0-20 ‰, known in the Mediterranean and western Europe (Athersuch et al., 1989). In Portugal found alive in the lower Minho and mid Lima estuaries, from the tidal flat to the low marsh (where it is much more abundant), in autumn and spring conditions (approximate salinity range of 1.1-22.9 ‰ and temperature 12.4-21.4 °C, in sediment interstitial water).
Krithe aff. praetexta (Sars, 1866) K. praetexta is a marine sublittoral species, living on sand and mud at depths of 50-500 m, from the British Isles to Sweden and norway (Athersuch et al., 1989). The Portuguese species, closely related but with a less rounded posterior margin, was found alive in sites 5 (94.0 m depth) and 6 (100.0 m depth), western Algarve continental shelf, in spring conditions.
Leptocythere baltica Klie, 1929 A marine/brackish nW European species, occuring from the Bay of Biscay to the Baltic, usually on sand substrates, but also in British low marsh, within an approximate salinity of 25 ‰ (Horne & Boomer, 2000). In Portugal found alive in the lower Minho and lower Lima estuaries, on sand to silty sand substrates of the tidal flat and low marsh, in autumn and spring conditions (approximate salinity range of 12.6-19.7 ‰ and temperature 11.7-19.3 °C, in sediment interstitial water).
Leptocythere ciliata Hartmann, 1957 A brackish species known from Germany (north Sea), also recorded in the British Isles by Horne (1980 -unpublished PhD thesis) and probably in nW Morocco (nachite et al., 2010, Pl. 2, fig. 15). In Portugal found alive in the lower Minho, lower and mid Lima, lower and mid (Trancão) Tejo, lower Sado and lower and mid Mira estuaries, from the tidal flat to the high marsh (more abundant on the low and high marsh), in autumn/winter and spring/ summer conditions (approximate salinity range of 2.5-47.5 ‰ and temperature 10.2-23.0 °C, in sediment interstitial water).
Leptocythere fabaeformis (G. W. Müller, 1894) A brackish (highly euryhaline -13-33 ‰), phytal/littoral marine species, known from the Mediterranean to western Europe, whose northern limit of distribution is apparently in France (Yassini, 1969). In Portugal found alive only in the tidal flat of the lower Mira estuary, as subordinate species, in autumn and spring conditions (approximate salinity 33.6 ‰ and temperature 16.3 °C, in sediment interstitial water).
Leptocythere lacertosa (Hirschmann, 1912) A common nW European brackish species usually inhabiting estuaries on mud or fine sand substrate; its geographical distribution spans from the Baltic Sea to the nW Morocco coast (nachite et al., 2010). In Portugal found alive from the tidal flat to the high marsh (more abundantly on the tidal flat and low marsh) of the lowest part of Minho (very rarely), lower Tejo, lower Sado and lower and mid Mira estuaries, in autumn/winter and spring/ summer conditions (approximate salinity range of 22.9-47.5 ‰ and temperature 13.6-21.7 °C, in sediment interstitial water).
Leptocythere porcellanea (Brady, 1869) A brackish nW European species usually living on mud substrates in estuaries and salt marshes from the Baltic to SW France (Horne & Boomer, 2000) and SW Spain (Ruiz et al., 2000). It is the most abundant species found alive in Portuguese tidal marshes of the lower Minho, mid Lima, lower and mid (Trancão) Tejo, lower Sado and lower and mid Mira estuaries, from the tidal flat to the high marsh, in autumn/winter and spring/summer conditions. It is frequently the dominant species in the low and/or in the high marsh in the SW estuaries (approximate salinity range of 2.5-47.5‰ and temperature 11.6-21.6°C, in sediment interstitial water).
Leptocythere psammophila Guillaume, 1976 An outer estuarine species inhabiting sandy substrates from the Atlantic coasts of France to Iceland and the Baltic (Athersuch et al., 1989) and nW Morocco (nachite et al., 2010); in the British Isles it was found in a low salt marsh, within a salinity range of 25-29 ‰ (Horne & Boomer, 2000). In Portugal found alive on sandy to silty sand substrates of the tidal flat of the lower Minho estuary, in autumn and spring conditions (approximate salinity range of 1.1-18.6 ‰ and temperature 18.5-21.4 °C, in sediment interstitial water).
Loxoconcha elliptica Brady, 1868 A common brackish species usually associated with algae and mud, known from the Mediterranean to nW Europe (Horne & Boomer, 2000) and nW Morocco (nachite et al., 2010). In Portugal found alive in lower Minho, lower and mid Lima, lower and mid (Trancão) Tejo, lower Sado and lower and mid Mira estuaries, from the tidal flat to the high marsh, in autumn/winter and spring/summer conditions (approximate salinity range of 1.1-34.3 ‰ and temperature 10.9-21.7 °C, in sediment interstitial water).
Loxoconcha malcomsoni Horne & Robinson, 1985 A rare brackish species, until now only known from the British Isles, living in salt marshes close to the tidal flat/low marsh limit, near marine salinity conditions (Horne & Boomer, 2000). In Portugal found alive in the lowest part of Mira and lower Sado estuaries, from the low to the high marsh, in autumn and spring conditions (approximate salinity range of 23.2-47.5 ‰ and temperature 14.4-17.2 °C, in sediment interstitial water).
Loxoconcha rhomboidea (Fischer, 1855) A common phytal, littoral/shallow sublittoral marine, nW European species (from norway to Madeira and Canary Islands - Athersuch et al., 1989), also found in salt marshes in slightly reduced salinities near the mouth of estuaries (Horne & Boomer, 2000); most Mediterranean records are doubtful, but some species from Cyprus and from the western part of the Mediterranean do appear to be L. rhomboidea (Athersuch & Whittaker, 1976). In Portugal very rarely found alive in the tidal flat of the lower Lima and lower Mira estuaries, in autumn and spring conditions (approximate salinity range of 24.8-33.8 ‰ and temperature 16.3-20.2 °C, in sediment interstitial water).
Paradoxostoma sarniense Brady, 1868 A phytal, marine/brackish species (tolerant to salinities as low as 25 ‰) apparently only known previously from the British Isles and France (Athersuch et al., 1989). In Portugal found alive on sandy substrate and red algae, in an intertidal rock pool near Laje River mouth, Santo Amaro de Oeiras beach, in spring conditions (approximate salinity range of 35.5-36.2 ‰ and temperature 26-29.4 °C, at low tide). Also found alive in the tidal flat of the lower Sado estuary, in autumn and spring conditions (approximate salinity range of 31.6-34.1 ‰ and temperature 13.8-18.7 °C, in sediment interstitial water).
Paradoxostoma trieri Horne & Whittaker, 1985 A phytal, littoral marine species, apparently only known previously from the British Isles and France (Horne & Boomer, 2000); in the British Isles it also lives in salt marshes at the limit tidal flat/low marsh (Horne & Boomer, 2000). In Portugal found alive on sandy substrate, green and red algae, in an intertidal rock pool near Laje River mouth, Santo Amaro de Oeiras beach, in spring conditions (approximate salinity range of 35.5-36.2 ‰ and temperature 26-29.4 °C, at low tide). Also found alive in the tidal flat of lower Sado and lower Mira estuaries, in autumn and spring conditions (approximate salinity range of 33.4-34.6 ‰ and temperature 15.9-17.6 °C, in sediment interstitial water).
Rectobuntonia rectangularis (Ruggieri, 1954) A marine sublittoral species known from the Mediterranean, found living at depths of 54-112 m, essentially on mud (Yassini, 1979, Pl. 4, figs 7 and15, as Buntonia subulata Ruggieri, 1954). In Portugal found alive in sites 3 (96.5 m depth) and 5 (94.0 m depth), on western Algarve continental shelf, in spring conditions. Semicytherura sella (Sars, 1866) A shallow-marine/outer estuarine species, living on silty and sandy substrates, in nW Europe, including norway and the Baltic Sea (Whittaker, 1974;Athersuch et al., 1989). In Portugal rarely found alive on muddy substrate in the tidal flat of the lowest part of Mira estuary, in spring conditions (approximate salinity range 32.8-35.8 ‰ and temperature 17.7-18.9 °C, in sediment interstitial water).
Semicytherura tela Horne & Whittaker, 1980 A littoral marine/brackish species found on algae in rock pools, in British Isles and France (Athersuch et al., 1989). In Portugal, found alive (only one specimen) on sandy substrate in an intertidal rock pool near Laje River mouth, Santo Amaro de Oeiras beach, in a salinity of 35.5 ‰ and a temperature of 26 °C, at low tide, in spring conditions.
Tuberoloxoconcha cf. atlantica Horne, 1989 T. atlantica is a marine, littoral, interstitial, western (Massachusetts, USA) and eastern (west Scotland) north Atlantic species (Horne, 1989). The Portuguese species, very similar but almost without ornamentation, was found alive only in the high marsh of lower Tejo and lower Mira estuaries, in autumn/winter and spring/summer conditions (approximate salinity range of 18.5-30.6 ‰ and temperature of 14.4-16.3 °C, in sediment interstitial water).
Tuberoloxoconcha sp. 1 A new brackish species found alive only in the transition zone between low and high marsh of lower Minho estuary (Coura confluence), in autumn and spring conditions, within an approximate salinity range of 10.1-22.9 ‰ and temperature of 12.9-15.4 °C, in sediment interstitial water.
Xestoleberis labiata Brady & Robertson, 1874 A shallow-marine species recorded previously only from the British Isles and France (Athersuch et al., 1989). In Portugal found alive on sandy substrate, green and red algae, in an intertidal rock pool near Laje River mouth, Santo Amaro de Oeiras beach, in spring conditions (approximate salinity range of 35.5-36.2 ‰ and temperature 26-29.4 °C, at low tide). Also found alive in the tidal flat of the lower Mira estuary, in autumn and spring conditions (approximate salinity range of 33.4-33.8 ‰ and temperature 16.0-16.3 °C, in sediment interstitial water). suMMary A total of 178 brackish and marine ostracod species belonging to 75 genera has been found and identified in Portugal, most of them as empty valves. From those species, 17 are referred to as aff. or in open nomenclature; some of them are probably new. Eighteen species are recorded as fossil only and 73 have no fossil record in the area. Thirty species were found alive, most of them living in littoral areas; only 4 species were found alive in the western zone of the continental shelf of Algarve, and none was found alive in the continental slope.

autochthonous fauna
The autochthonous fauna of the estuaries comprises 25 species, distributed in the high and low tidal marshes and in the tidal flat. Almost all the species are known in marginal-marine settings of the Atlantic coast of nW Europe -Spain, France, UK, Ireland, Belgium, The netherlands and, for 10 of the species, even norway, Sweden and the Baltic Sea (Cyprideis torosa, Cytherois fischeri, Heterocythereis albomaculata, Leptocythere baltica, L. lacertosa, L. porcellanea, L. psammophila, Loxoconcha elliptica, L. rhomboidea, Semicytherura sella) and also in both the Atlantic and Mediterranean coasts (9 species: Basslerites teres, Callistocythere badia, Cyprideis torosa, Cytherois fischeri, C. cf. stephanidesi, Hemicytherura videns, Heterocythereis albomaculata, Leptocythere fabaeformis, Loxoconcha elliptica). Two phytal species live in the lower estuaries, being found alive very rarely, but with very abundant empty valves in the tidal flat: Hemicytherura videns (also in the lower part of the low marsh) and Loxoconcha rhomboidea. The phytal Paradoxostoma sarniense, P. trieri and Xestoleberis labiata were found alive in the tidal flat of the SW Portuguese estuaries, in a near-marine salinity range (31.6-34.6 ‰). Heterocythereis albomaculata, also a phytal species, was found alive associated with green algae, always submerged (even at low tide), in the lowest part of Laje river estuary, in the confluence with Tejo, in a salinity of 28.9 ‰. Five brackish species, preferring a muddy substrate and with a wide salinity tolerance can be found in all the three environments, tidal flat, low and high marsh: Cyprideis torosa, Leptocythere ciliata, L. lacertosa, L. porcellanea and Loxoconcha elliptica.
In the tidal flat, generally muddy, where the emersion time (time of subaerial exposure between tides) ranges between 12 % and 70 % and the salinity is highly variable, but no higher than 35‰, the number of species is high. Twenty species were found alive, from which eight are restricted to the tidal flat: L. rhomboidea, P. sarniense, P. trieri, X. labiata, Basslerites teres, Leptocythere fabaeformis, L. psammophila and Semicytherura sella. Leptocythere psammophila is associated with fine sand substrate. Cytherois fischeri is found both in the tidal flat and in the lower part of the low marsh, but it is much more abundant in the tidal flat. The most abundant species in the tidal flat are L. elliptica, C. fischeri, L. porcellanea and Leptocythere sp. A in the nW estuaries and C. fischeri, L. elliptica, C. torosa and L. lacertosa in the SW ones. The dominant species differs from one estuary to another and according to the location of the transect inside the estuary. In the tidal flat of the lower Lima and the lower Mira estuaries, empty valves of over 25 and 80 marine species, respectively, which do not live in these estuaries, were transported in by tidal currents.
In the low marsh, generally muddy, with emersion time around 75-90 % and variable salinity (always lower in the nW estuaries, higher in the SW ones, where frequently it exceeds 35 ‰), fourteen species were found alive, all of them also found in the tidal flat and/or in the high marsh. The most frequent species in the low marsh are L. porcellanea, L. ciliata and L. lacertosa, present in almost all the estuaries and frequently dominant. In the nW estuaries, in addition to L. porcellanea and L. ciliata, Cytherois cf. stephanidesi, Leptocythere sp. A and L. elliptica are also well represented, particularly in the autumn. In the SW estuaries L. porcellanea and L. lacertosa are the dominant species, with L. ciliata, L. elliptica and C. torosa sometimes well represented. Among the other species also recorded alive in the low marsh are L. baltica and Leptocythere sp. B in the nW estuaries, L. malcomsoni in the SW ones, C. murrayi and C. fischeri in both; very rarely, Tuberoloxoconcha sp. 1 and H. videns occur, each one in one of the estuaries.
The high marsh, with a long emersion time (93-99.5 %) and wide range of salinity values (frequently very low, reaching 2.5 ‰ in the nW estuaries and very high, reaching 45-50 ‰ in the SW estuaries), is often barren of ostracods. Besides the five very tolerant brackish species found in some high marshes (generally in the lower part), three other species have been recorded living there: Tuberoloxoconcha sp. 1 in the nW Minho estuary, characterized by low salinities at low tide and Tuberoloxoconcha cf. atlantica and Terrestricythere aff. elisabethae in the SW estuaries. Though more abundant in the low marsh, Loxoconcha malcomsoni is also found inhabiting the lower part of the high marsh in two SW estuaries.
In the marine littoral settings, only two intertidal rock pools were studied, where six species were found living on algae or in sandy substrate, within a salinity around 35.5-36 ‰: Callistocythere badia, Heterocythereis albomaculata, Paradoxostoma sarniense, P. trieri, Semicytherura tela (only in the substrate) and X. labiata.
continental shelf and slope. On the continental shelf and slope 86 species were recognized, from which 10 were found only in the continental slope. Over 30 % of the species are known, until now, both in the Atlantic Ocean and in the Mediterranean Sea, with at least 27 recorded only in the Mediterranean Sea and 19 only in the Atlantic Ocean. On the continental shelf the most common species, represented by abundant and complete populations (with all or almost all ontogenic stages, though all dead), are: Costa runcinata, Palmoconcha guttata, Krithe aff. praetexta, Pterygocythereis jonesii and Henryhowella sarsii (this species only abundant around or below -125 m depth). Rectobuntonia rectangularis, Celtia quadridentata and Cytheropteron cf. ruggierii are not abundant but are frequently present. Only four species have very few specimens found alive: Basslerites teres, Bosquetina tarentina, K. aff. praetexta and R. rectangularis. B. teres is found alive as deep as 96.5 m, but is more frequent in shallower water. In the continental slope no species were found alive. The assemblages are dominated by K. aff. praetexta and H. sarsii around -220 m depth and by Paracypris polita, K. aff. praetexta and K. keyi around -500 m depth.

holocene
In the Holocene the ostracods characterize different environments and help to build a general evolutionary model of the studied marginalmarine regions since the Lateglacial (Cearreta et al., 2003;Freitas et al., 2003). This model includes several palaeoenvironmental stages, with the earliest and the latest being characterized by sediments barren in ostracods. The first stage (Lateglacial to Early Holocene), lacking ostracods, was interpreted as a high-energy fluvial environment, contemporaneous with a sea level significantly lower than present. In the second stage (Early Holocene), ostracods are present, at first represented by brackish forms (generally C. torosa and L. elliptica), progressively replaced by littoral and sublittoral marine species, the most abundant being: Urocythereis britannica, Pontocythere elongata, Basslerites teres, Carinocythereis whitei, Semicytherura robertsi, S. sella, X. labiata, L. rhomboidea, Aurila convexa. The maximum signal of marine influence in the sedimentary record is represented by the highest diversity in ostracods, including some deeper-water marine species, such as Celtia quadridentata, Cytheropteron dorsocostatum, C. depressum, Roundstonia robertsoni. This stage corresponds to the progressive development of an estuarine environment that further evolved to fully marine, due to the rapid sea-level rise during the Holocene transgression. A third stage (Middle and Late Holocene) is contemporaneous with a pronounced decrease in the rate of sea-level rise followed by stabilization of mean sea level. In this stage, brackish (and sometimes, rare freshwater) ostracods are once more present: C. torosa and L. elliptica if the marginal zone evolved to a barrier-lagoon system or C. torosa, L. elliptica, Cytherois fischeri, L. porcellanea, L. lacertosa (and many littoral marine/slightly brackish species) if the environment remained as an open estuary with marginal tidal marshes. The last stage (Late Holocene), lacking ostracods, corresponds to the terrestrialization of the former marginal marine systems, which became progressively shallower and smaller, due to significant input of terrestrial-sourced sediment settling in low energy depocentres and retained in alluvial fans and plains prograding and accreting over former intertidal space. In consequence, the environment resumed essentially freshwater and fluviatile conditions that persisted until present.

conclusIons
To assist both monitoring of contemporary environmental change and to assist reconstruction of Holocene palaeoenvironments, we list and figure 30 living ostracod species from a range of marginal to marine environments in Portugal. In addition, we list and figure 148 species for which we have only the calcareous carapaces or valves, some of which appear to be restricted to the Holocene and are not known living in the area.
Knowledge of Recent Portuguese ostracods is fair for the western estuarine zones, but very incomplete for the marine littoral and sublittoral zones, where only two intertidal rock pools near Lisbon and a very small area from the continental shelf and slope in south Portugal have been studied. Holocene ostracods are relatively well known in the marginal-marine settings, particularly in the lagoons.
With this work, ostracod biogeographical patterns between nW European waters and the Mediterranean Sea are clarified, with some nE Atlantic species whose southern distribution limit was set in northern Spain (Bay of Biscay) now shown to live further to the south in Portugal. Most of the listed species are typical nE Atlantic forms, especially the Recent ones, found living or accumulated in the western Portuguese estuaries, but in Algarve, in the continental shelf and slope faunas, a Mediterranean influence is clearly stronger than in the other studied environments. In future research it will be very interesting to check whether this influence is also that important in the marginal littoral Algarve assemblages.

note added In-Press
After manuscript acceptance, further work on the western Algarve continental slope revealed 19 more Recent ostracod species and eight more genera not previously reported in the main list. All were found on the continental slope, between 230 and 513 m depth; only 2 species were found alive. The discoveries modify some of the manuscript data (total number of species and genera, number of live species, etc) particularly the Abstract, which are not possible to change at this stage.