Skip to main content
NCBI home page
Zoological Studies logoLink to Zoological Studies
. 2022 Dec 20;61:e77. doi: 10.6620/ZS.2022.61-77

On a New Species of Pseudocypretta Klie, 1932 (Crustacea, Ostracoda) from the Neotropical Region, with a Discussion on the Position of the Genus

Vitor Góis Ferreira 1,*, Nadiny Martins Almeida 1, Janet Higuti 1,2,#, Koen Martens 3,4,#
PMCID: PMC10061318  PMID: 37007818

Abstract

Pseudocypretta amor sp. nov. (named after the carapace spots resembling the word “Love”) is here described from all-female populations from the four major floodplains in Brazil. The new species is compared to the other two known species in the genus, P. maculata Klie (1932), the type species, and P. lineata Ma and Yu (2020). As the latter two species are thus far found exclusively in South East Asia and China, respectively, the present extension of the area of the genus to South America is considerable. Several morphological characters in this genus and species are discussed, especially the presence of marginal septa in the valves, the candonid type T3 with 3rd and 4th segment separated (candonid type) and the caudal ramus which is reduced to a flagellum (cypridopsine type) or is fully absent. Based on the combination of these and other characters, the genus Pseudocypretta is here transferred from the Cyprettinae to the tribe Cyprettadopsini in the Cypridopsinae, as it is closely related to the genus Cyprettadopsis Savatenalinton, 2020. The presence of the candonid type T3 in Cyprididae and Notodromadidae, where the T3 generally has a pincer-shaped tip by the fusion of the 3rd and the 4th segment, is further discussed.

Keywords: Areal extension, Neotropics, Comparative morphology, Taxonomy, Circumtropical

BACKGROUND

The subfamily Cyprettinae Hartmann, 1963 comprises two genera: Cypretta Vávra, 1895 and Pseudocypretta Klie (1932) (Meisch et al. 2019). Cypretta presently holds 52 species worldwide and is considered a circumtropical genus, owing to the high diversity of species in the tropical and subtropical regions (Cohuo-Durán et al. 2013; Meisch et al. 2019). Pseudocypretta, on the other hand, comprises only two species: Pseudocypretta maculata Klie (1932) and Pseudocypretta lineata Ma and Yu (2020), both from the Oriental region, inhabiting rice fields, pools, lakes and streams (Klie 1932; Savatenalinton 2018; Ma and Yu 2020).

The Neotropical region has a high aquatic biodiversity (Balian et al. 2008). However, the ostracod fauna is still largely overlooked in most biological surveys. Recent sampling efforts discovered several new taxa from various environments, such as semi-terrestrial and river-floodplain systems (e.g., Pinto et al. 2003 2005; Higuti et al. 2013; Ferreira et al. 2019 2020; Almeida et al. 2021). While sampling in the four major Brazilian floodplains during the SISBIOTA project (2010–2014), several species of the genus Cypretta were collected (Pereira et al. 2017 and unpublished data), and one was referred to as Cypretta sp.3 in Higuti et al. (2010) because of its overall morphological similarity to other Cypretta species, namely the general globular shape of the carapace and the presence of marginal septa along the (anterior) valve margins of both valves. However, after more detailed morphological analyses of the valves and appendages, the species was identified as belonging to the genus Pseudocypretta.

Pseudocypretta species also have a globular carapace with a length between 0.4 and 0.5 mm, with marginal septa along anterior and posterior margins in both valves and thus, with these characters, resemble species of the genus Cypretta. But in the two species of Pseudocypretta, the left valve overlaps the right valve anteriorly (inverse in Cypretta), while they also have a third thoracopod marked by a separate fourth segment (fused into a pincer-shaped organ in Cypretta, and in most subfamilies in the Cyprididae) and a caudal ramus which is reduced to a flagellum-like structure, the so-called cypridopsine type (the CR is more developed with ramus, claws and setae in Cypretta).

Here, we describe a new species of Pseudocypretta, and discuss the morphology of the species in this genus. We also discuss the distribution of this species and genus respectively across Neotropical Brazilian floodplains and globally.

MATERIALS AND METHODS

Study area

The study was conducted in the main four Brazilian floodplains: Amazon (3°02'–3°34'S, 60°50'–60°10'W), Araguaia (12°50'–13°20'S, 50°40'–50°30'W), Pantanal (18°50'–19°30'S, 57°40'–57°00'W), and Upper Paraná (22°40'–24°00'S, 54°20'–53°00'W) (Fig. 1). Together, these floodplains comprise a large area of Brazil and hold different types of habitats such as rivers, channels, backwaters, and open and closed lakes (Agostinho et al. 2004; Barros et al. 2004; Harris et al. 2005; Latrubesse et al. 2009).

Fig. 1.

Fig. 1.

Open in a new tab

Map of the study area of the Brazilian floodplains and the occurrences of Pseudocypretta amor sp. nov.

The Amazon is located in the circumtropical belt of evergreen tropical rainforest at the equator region. It is distributed along several countries in South America, such as Brazil, Bolivia, Colombia, Ecuador, French Guiana, Peru, Suriname and Guyana (Junk et al. 2011). The Amazon River floodplain is in the north region of Brazil, and is composed by a mosaic of extensive rivers, such as the Negro River and Solimões River, as well as the Amazon River itself and lakes. Over the last several decades, a great area of tropical forest has been destroyed by logging and replaced by herbaceous vegetation (Junk et al. 2011). All samples were taken from sites near Manaus city.

The Araguaia River floodplain is situated in the central region of Brazil, in the transition zone between the Amazon Forest and the tropical savanna forest. Its surroundings have experienced extensive landscape changes owing to expanding farming and logging activities, making it a priority area for conservation (Latrubesse et al. 2009). Samples were collected in the central stretch of the Araguaia River.

The Pantanal, which contains the Paraguay River, is part of one of the largest wetlands in the world, distributed across the Brazilian states of Mato Grosso and Mato Grosso do Sul, as well as parts of Bolivia and Paraguay. This region holds high biodiversity and is equally a priority in conservation strategies (Barros et al. 2004). Samples were collected in the Pantanal of the Mato Grosso do Sul State.

Finally, the Upper Paraná River floodplain is located in a region with one of the highest population densities of Brazil, thus suffering from human impacts such as tourism, overfishing, pollution and extensive flow regulation by damming (Agostinho et al. 2004). It comprises three conservation units: “Área de Proteção Ambiental das Ilhas e Várzeas do Rio Paraná”, the “Parque Nacional de Ilha Grande”, and the “Parque Estadual do Ivinheima”, which were created to preserve the high biodiversity found in this region (Agostinho et al. 2004). Samples were collected in the stretch between Porto Primavera and Itaipu dams.

Sampling

Sampling was performed between 2004 and 2020 in the Upper Paraná River floodplain, and between 2011 and 2012 in the Amazon, Araguaia and Pantanal floodplains. In the Pantanal floodplain, sampling was also done in 2003. Samples were taken amongst aquatic plants as well as sediment in the littoral region. The macrophytes were hand-collected, and whole plants or roots were washed in a bucket to remove the ostracods (see Campos et al. 2017). This material was then filtered in a net of 160 μm mesh size and preserved in 70% ethanol buffered with sodium tetraborate. Samples from the littoral region were performed in situ with a rectangular hand net (28 cm × 14 cm, mesh size approximately 160 μm).

Environmental variables (water temperature (WT) and dissolved oxygen (DO) concentration (YSI 550A oximeter), pH (pHmeter Digimed) and electrical conductivity (EC) (conductivimeter-Digimed), were measured in situ, close to the macrophytes and/or sediment.

Preparation and illustration of soft parts and valves

Specimens were dissected with hand-held small needles under a binocular microscope. The ostracod carapace was first opened, and the valves were separated from the soft parts. Soft parts were then dissected in a drop of glycerine on a glass slide. The dissected appendages were covered with cover-slip and sealed with transparent nail polish. Valves were stored dry in a micropaleontological slide. Drawings of the appendages were made using a camera lucida (Olympus U-DA) attached to an optical microscope (Olympus CX-41). Carapaces and valves were illustrated and measured using Scanning Electron Microscopy (SEM; Fei Qanta 200 ESEM, -Royal Belgian Institute of Natural Sciences, Brussels, Belgium) in different views (internal, lateral, dorsal, ventral and frontal). To illustrate the septa on the margin of the valves, both valves were placed on a concave microscope slide in glycerine sealed with cover slip and drawn using a camera lucida attached to an optical microscope (see above).

The type material and illustrated specimens are stored in the collection of the Museum of Zoology of the University of São Paulo (São Paulo, Brazil –MZUSP).

Thoracopod terminology follows Broodbakker and Danielopol (1982), second antenna terminology follows the revised model proposed by Martens (1987), and of the second and third thoracopods terminology follows Meisch’s nomenclature (2000). Higher taxonomy of the Ostracoda follows Horne et al. (2002) and Meisch et al. (2019).

RESULTS

Class Ostracoda Latreille, 1802

Subclass Podocopa G.O. Sars, 1866

Order Podocopida G.O. Sars, 1866

Suborder Cypridocopina G.O. Sars, 1866

Superfamily Cypridoidea Baird, 1845

Family Cyprididae Baird, 1845

Subfamily Cypridopsinae Kaufmann, 1900

Tribe Cyprettadopsini Savatenalinton, 2020

Genus Pseudocypretta Klie, 1932

Diagnosis: Cp highly arched, sub-triangular in lateral view, rounded in dorsal and ventral views; LV overlapping RV at least anteriorly and ventrally. Coloration patchy and variable. RV with fully-developed marginal septa along anterior and posterior margin; LV with incomplete marginal septa. LV with a large inner list, running parallel to (part of) the anterior margin, straight and obliquely away from the postero-ventral margin. RV with selvage weakly inwardly displaced along the postero-ventral margin. Both valves with external lists, most developed on LV; these lists not perforated by pores. A1 with relatively short segments. A2 with natatory setae extending beyond tips of distal claws, claw G2 more strongly developed and serrated than the other claws. Md-palps with alpha seta short, slender and smooth; beta seta short, stout and hirsute; gamma seta long, slender and hirsute. Mx1 with second palp segment rectangular, tooth bristles on third endite smooth. T2 with penultimate segment divided; seta d2 well-developed; seta d1 absent; claw h2 unusually strongly curved. T3 with 4th segment separate from 3rd, distally with seta h2 relatively short. CR minute, with base and distal seta fused, or fully absent. Male unknown.

Type species: Pseudocypretta maculata Klie (1932).

Other species: P. lineata Ma and Yu (2020), P. amor sp. nov.

Differential diagnosis: Pseudocypretta is closely related to Cyprettadopsis and shares many characters and character states, but the two genera also have some important morphological differences. Cyprettadopsis is much more elongated than the three species of Pseudocypretta, it has a different arrangement of the marginal septa (anteriorly incompletely developed and posteriorly fully developed in both valves in Cyprettadopsis, fully developed in the RV and incompletely developed in the LV in Pseudocypretta), the external lists in the two genera are differently developed, with Cyprettadopsis having additional pores there, and the inner list in the LV has a posteroventral deviation from the valve margin which is significantly larger in Pseudocypretta than in Cyprettadopsis (a longer part is straight and not following the curve of the valve margin).

Pseudocypretta amor sp. nov.

(Figs. 2–9)

urn:lsid:zoobank.org:act:22464BB8-0498-435E-8A51-811157C10DEC

“Cypretta” sp. 3 –Higuti et al. 2009: 664, Table 1; 2010: 267, Table 2.

“Cypretta” n. sp. –Matsuda et al. 2015: 326, Table 1; Higuti et al. 2017b: 5, Apêndice 1.

“Cypretta” sp. 3 n. sp. –Higuti et al. 2017a: e120, Table 2.

“Cypretta” n.sp. 3 –Pereira et al. 2017: 327, Table 2; Campos et al. 2021: 27, Table 1.

“Cypretta” sp. 2 n. sp. –Campos et al. 2018: 6, Table 2.

Type locality: Garças Lake (PAR 982) in the Upper Paraná River floodplain. Coordinates: 22°43'31.1"S, 53°13'08.4"W.

Material examined: Holotype: 1 ♀, with soft parts dissected in glycerine in a sealed slide and with valves stored dry in a micropaleontological slide (MZUSP 43014), collected in February 2014, in Garças Lake (PAR 982) by Janet Higuti and Eliezer de Oliveira da Conceição. Paratypes: 3 ♀ with soft parts dissected as the holotype (MZUSP 43008, MZUSP 43015 and MZUSP 43016), 6 ♀ carapaces stored dry in micropaleontological slides after use for SEM illustrations (MZUSP 43009, MZUSP 43010, MZUSP 43011, MZUSP 43012, MZUSP 43013 and MZUSP 43017), collected in February 2014 in Garças Lake (PAR 982) by Janet Higuti and Eliezer de Oliveira da Conceição.

Other material illustrated: Amazon River floodplain: 1 ♀ with soft parts dissected as the holotype (MZUSP 43018); 3 ♀ carapaces stored dry in micropaleontological slides after use for SEM illustrations (MZUSP 43019, MZUSP 43020 and MZUSP 43021), collected in May 2012 in Poço Curuça Lake (AMA AMA59, 60) by Janet Higuti. Araguaia River floodplain: 1 ♀ with soft parts dissected as the holotype (MZUSP 43022); 5 ♀ carapaces stored dry in micropaleontological slides after use for SEM illustrations (MZUSP 43023, MZUSP 43024, MZUSP 43025, MZUSP 43026 and MZUSP 43027), collected in March 2012 in Varal Lake (ARA80) by Janet Higuti and Koen Martens. Pantanal: 2 ♀ with soft parts dissected as the holotype (MZUSP 43032 and MZUSP 43028); 3 ♀ carapaces stored dry in micropaleontological slides after use for SEM illustrations (MZUSP 43029, MZUSP 43030 and MZUSP 43031), collected in June 2003 in Corumbá Road II temporary pool (PAN 15) by Janet Higuti, Koen Martens and Kennedy Francis Roche.

Etymology: The species is named after its colour pattern on the carapace in dorsal view, which looks like the word “love” (amor is “love” in Latin) (Fig. 2).

Fig. 2.

Fig. 2.

Open in a new tab

A, coloured photo of Pseudocypretta amor sp. nov.; B, illustration showing the word “love” on the carapace surface; C, illustration highlighting the letters of the word “love”.

Diagnosis: Carapace rounded in dorsal and ventral views and with sub-triangular shape in lateral view, carapace surface set with a few shallow pits; LV overlapping RV along anterior and ventral margins; LV with large outer list along anterior, ventral and posterior margins; RV with ca. 11 fully developed marginal septa; LV with septa incompletely developed. A2 with claw G2 stronger developed and serrated than other claws. Mx1 with sideways directed bristles absent; first segment of Mx1-palp with sub-apical seta present; second segment elongated, L c. twice W; first endite with three apical claws; third endite with two smooth bristles. Md-palp third segment with three dorsal setae. T1 with setae b and d absent. T2 with seta d1 absent and penultimate segment undivided, claw h2 unusually strongly curved. T3 with fourth segment not fused with third segment and carrying three apical setae. CR fully absent. Male unknown.

Description of female: LVi (Figs. 3A, 4A) with inner lamella wide along anterior margin, absent along ventral, and narrow along posterior margins; inner groove running parallel to the ventral margin; large outer list running to halfway the anterior margin, almost parallel along the ventral margin and forming an inner groove there, and straight, not parallel to the ventro-posterior margin, showing an outward doubling on this straight part; ca. 12 septa weakly developed along the anterior margin and ca. 5 septa weakly developed along the posterior margin (Fig. 3G, H –indicated by white arrows -4A). RVi (Figs. 3B, 4B) with inner lamella wide along anterior margin, absent along ventral and narrow along posterior margins; with a weak inner list along anterior-ventral margin, both inner list and inner groove along ventral margin absent; posterior margin with an inwardly displaced selvage; ca. 11 septa along the anterior margin and ca. five septa along the posterior margin (Fig. 4B). Central muscle scars (Fig. 3A, B) forming a simplified paw-print pattern, consisting of an anterior (oblique) row of 3 rounded scars of intermediate size, one large rounded scar posterior of this row and two small rounded scars below these four larger scars. CpRl (Fig. 3C) with a rounded, subtriangular shape; greatest height situated in the middle; LV overlapping RV at the anterior, dorsal and ventral margins. CpD and CpV (Fig. 3D–E) with oval shape, posteriorly slightly broader than anteriorly, the latter bluntly pointed; greatest width situated slightly posteriorly to the middle. CpV with LV overlapping RV, in the middle region with a rounded expansion; both valves with clear external list, the one on the LV valve being the largest and running along anterior, posterior and ventral valve margins. CpFr (Fig. 3F), with LV overlapping RV, showing the robust external list on the LV. Cp surface (Fig. 3C–F) with a few shallow pits and no clear setae.

Fig. 3.

Fig. 3.

Open in a new tab

Carapace and valves of Pseudocypretta amor sp. nov. from Upper Paraná River floodplain, Garças Lake (PAR 982). A, LVi (MZUSP 43014); B, RVi (MZUSP 43014); C, CpRl (MZUSP 43009); D, CpD (MZUSP 43010); E, CpV (MZUSP 43011); F, CpFr (MZUSP 43012); G, LVi, detail of septae on posterior margin (MZUSP 43014); H, LVi, detail of septae on anterior margin (MZUSP 43014). Scale bars: A–F = 300 μm; G–H = 100 μm.

Fig. 4.

Fig. 4.

Open in a new tab

Valves inner view of Pseudocypretta amor sp. nov. from Upper Paraná River floodplain, Garças Lake (PAR 982), indicating the septae. A, LVi (MZUSP 43017); B, RVi (MZUSP 43017). Scale bars: A–B = 100 μm.

A1 (Fig. 5A) composed of seven segments. First segment with two long ventral and one short dorsal setae (ca. 1/3 the length of ventral setae). Second segment with one dorsal seta (ca. 3/4 the length of the third segment) and an elongated lateral R, only slightly shorter than the segment. Third segment with one short ventro-apical seta and one long dorsal seta (almost reaching end of terminal segment). Fourth segment with two short ventral setae (the shortest ca. 3/4 of length of the longest) and two long dorsal setae. Fifth segment with two long dorsal setae. Sixth segment with four long apical setae. Terminal segment with one long aesthetasc (Ya), one short seta (with the same length of Ya) and two long setae. WO not seen.

A2 (Fig. 5B, C) composed of five segments (one protopodite, one reduced exopodite and three endopodite segment). Protopodite carrying two short and one long ventral seta (ca. twice the length of the short ones). Exopodite consisting of a small plate with three setae, two short and one long (reaching beyond the tip of the second endopodite). First endopodal segment with one ventral aesthetasc Y, ca. half the length of the segment; one long ventro-apical seta ca. the length of the segment and five long natatory setae (reaching beyond the tips of the G claws) and one short seta (almost reaching the tip of the second endopodal segment). Second endopodal segment with a group of four medio-ventral t setae of unequal length (two reaching halfway z2, one slightly shorter and one short), and a group of two unequally short medio-dorsal setae; three long z setae (z1, z2 and z3); and three claws (G1, G2 and G3); claw G2 stronger developed and serrated than the other two claws. Terminal segment (Fig. 5C) with one long claw GM, and one short Gm; one aesthetasc y3 and its accompanying seta (slightly longer than y3); seta g absent.

MdCoxa (Fig. 5D) a plate with ca. six apical teeth intercalated with setae; one hirsute sub-apical seta on the dorsal margin.

Fig. 5.

Fig. 5.

Open in a new tab

Appendages of Pseudocypretta amor sp. nov. from the Upper Paraná River floodplain, Garças Lake (PAR 982). A, A1 (MZUSP 43015); B, A2 (MZUSP 43015); C, A2 terminal segment (MZUSP 43015); D, MdCoxa (MZUSP 43015). Scale bars = 50 μm.

MdPalp (Fig. 6B, C) four segmented. First segment ventrally with plumose setae S1 and S2; one long smooth seta and one short α seta (ca. 1/6 the length of the smooth seta). Second segment ventrally with a short cone-shaped and hirsute β seta and three long smooth setae; dorsally with a group of three subequal but long setae. Third segment dorsally with a group of four subequal setae; apically with three long setae and one long hirsute seta γ. Last segment (Fig. 6C) with three claws and one seta.

Mx1 (Fig. 6A) composed of a two-segmented palp, three endites and a large respiratory plate (the latter not illustrated). Basal segment of the palp with a group of five unequally long apical setae and one lateral seta. Terminal segment elongated (L ca. twice W), apically with three claws. First endite with two large bristles; and one medio-lateral seta (ca. slightly longer than the endite). Third endite with two basal setae. (Remark: chaetotaxy of endites incomplete, also in figure 6A, only major features described).

T1 (Fig. 6D) composed of an endopodite and a protopodite. Endopodite a conical palp, apically with three hirsute setae, two equally long and one short (ca. 2/3 the length of the longer ones). Protopodite with two equally short a-setae, and eight apical hirsute and unequally long setae; setae b and d missing.

T2 (Fig. 6E) composed of a five segmented walking leg. First segment with seta d1 absent. Second segment with a smooth seta d2. Third segment with apical seta e hirsute and long (reaching beyond the middle of the fourth segment). Fourth segment medially with seta f hirsute and long; and apically with a small seta g (reaching half the length of terminal segment). Terminal segment rectangular, apically with one short ventral setae h1, a long and strongly curved claw h2, and a short dorsal seta h3.

T3 (Fig. 6F) composed of four segments. First segment elongated, with one short hirsute seta d1 and two slightly longer and hirsute setae dp and d2. Second segment elongated, with a short hirsute apical seta e. Third segment with small hirsute sub-apical seta f, (1/4 the length of the segment). Terminal (4th) segment separated from penultimate (3rd) segment (candonid type), with one long, thin and hirsute seta h1, one claw-like seta h2 and one short hirsute seta h3, the latter not reflexed.

Fig. 6.

Fig. 6.

Open in a new tab

Appendages of Pseudocypretta amor sp. nov. from the Upper Paraná River floodplain, Garças Lake (PAR982). A, Mx1 (MZUSP 43015); B, MdPalp (MZUSP 43008); C, MdPalp terminal segment (MZUSP 43008); D, T1 (MZUSP 43016); E, T2 (MZUSP 43008); F, T3 (MZUSP 43014). Scale bars = 50 μm.

CR fully absent.

Male unknown.

Measurements of illustrated specimens: See table 1.

Remarks: For comparative purposes, additional illustrations of valves and carapaces are given for populations from the Amazon River floodplain (Fig. 7), the Araguaia River floodplain (Fig. 8) and the Pantanal (Fig. 9). The individuals of these Brazilian floodplains share the same characteristics in the carapace, valves and appendages, despite some small size differences observed (see Table 1). The LVi of Pseudocypretta amor sp. nov. from the Pantanal shows some damage in the dorsal position, resulted from the dissection. Several trials were made with other individuals to obtain an undamaged LVi but were unsuccessful owing to the fact that these valves were slightly decalcified and the soft parts were stuck by the adductor muscles to this valve. The decalcification of these valves, however, allows to see the marginal septa in the LV (Fig. 9A, H), even with non-transparent microscopy.

Fig. 7.

Fig. 7.

Open in a new tab

Carapace and valves of Pseudocypretta amor sp. nov. from Amazon River floodplain, Poço Curuça Lake (AMA59, 60). A, LVi (MZUSP 43018); B, RVi (MZUSP 43018); C, CpRl (MZUSP 43019); D, CpD (MZUSP 43020); E, CpV (MZUSP 43021); F, CpFr (MZUSP 43019); G, Cp, LVi, detail of septae on posterior margin (MZUSP 43018); H, LVi, detail of septae on anterior margin (MZUSP 43018). Scale bars: A–F = 300 μm; G–H = 200 μm

Fig. 8.

Fig. 8.

Open in a new tab

Carapace and valves of Pseudocypretta amor sp. nov. from Araguaia River floodplain, Varal Lake (ARA80). A, LVi (MZUSP 43022); B, RVi (MZUSP 43022); C, CpRl (MZUSP 43027); D, CpD (MZUSP 43027); E, CpV (MZUSP 43026); F, CpFr (MZUSP 43026); G, CpRl, detail of anterior margin (MZUSP 43027); H, LVi, detail of septae on anterior margin (MZUSP 43027). Scale bars: A–H = 300 μm; G–H = 150 μm.

Fig. 9.

Fig. 9.

Open in a new tab

Carapace and valves of Pseudocypretta amor sp. nov. from Pantanal, Corumba Road II (PAN15). A, LVi (MZUSP 43028); B, RVi (MZUSP 43028); C, CpRl (MZUSP 43029); D, CpD (MZUSP 43030); E, CpV (MZUSP 43031); F, CpFr (MZUSP 43030); G, LVi, detail of septae on posterior margin (MZUSP 43028); H, LVi, detail of septae on anterior margin (MZUSP 43028). Scale bars: A–F = 300 μm; G–H = 100 μm.

Table 1.

Measurements (in μm) of carapaces and valves of specimens of Pseudocypretta amor sp. nov. in different views

graphic file with name zoolstud-61-077-t001.jpg

Open in a new tab

Differential diagnosis: The new species can be distinguished from Pseudocypretta lineata by the presence of linear ridges on the carapace surface in P. lineata (valve are smooth in P. amor sp. nov.); the anterior part of the inner list in the LV runs much higher in P. lineata; the Cp is wider in P. lineata and the greatest width is situated behind the middle, while also the posterior part is somewhat invaginated; the setae on the last segment of T3 are shorter and the CR is completely absent in P. amor sp. nov.

The new species is more similar to P. maculata, but differs from it by the fact that in P. maculata the RV clearly overlaps the LV at the posterior region, while in Pseudocypretta amor sp. nov. both valves extend equally there; the Cp is more highly arched in P. maculate and the colouration is reduced to isolated spots; the A2 on P. maculata has a short terminal segment (L less than 1.5x W), while in P. amor sp. nov. the L is ca. 1.5x W; the last segment of the T3 has a long-reflexed seta h3 in P. maculata, while in Pseudocypretta amor sp. nov., this seta h3 is short and is not reflexed; P. maculata has a CR as a reduced flagellum, while the CR is fully absent in P. amor sp. nov. These differences are summarized in table 2.

Table 2.

Comparative morphology of the three known species of Pseudocypretta, based on the original descriptions

graphic file with name zoolstud-61-077-t002.jpg

Open in a new tab

Ecology and distribution: Pseudocypretta amor sp. nov. was recorded in the four main Brazilian floodplains, Amazon, Araguaia, Pantanal, and Paraná, with the major distance between two of these floodplains of 2.300 km (Fig. 1). The species was recorded in a wide range of environmental variables, such as 17.1–35°C for WT, 5.71–8.23 for pH, 8.1–222.5 μS.cm-1 for EC and 1–7.28 mg.L-1 for DO. The species was associated with the root systems of aquatic macrophytes and was also collected from sediment. Detailed information about environmental data is listed in table 3.

Table 3.

Environment type, substrate and abiotic variables of localities from where Pseudocypretta amor sp. nov. was recorded in the river-floodplain system of Amazon, Araguaia, Pantanal, and Paraná. Type locality in bold

graphic file with name zoolstud-61-077-t003.jpg

graphic file with name zoolstud-61-077-t004.jpg

Open in a new tab

DISCUSSION

Occurrence of the genus Pseudocypretta

Pseudocypretta maculata was described by Klie (1932) from lakes and rice fields of Sumatra and Java. The original description lacks details about the species’ morphology, with illustrations of only carapace, antenna, second and third thoracopod and caudal ramus. Later, Battish (1978 1982) and Karuthapandi et al. (2014) reported this species from India, Victor and Fernando (1981) from Malaysia and Neale (1984) from Sri Lanka, while Savatenalinton and Martens (2009 2010), Savatenalinton (2014 2017) and Savatenalinton and Suttajit (2016) reported P. maculata from various habitats in Thailand, indicating that this species is quite common in South East Asia (Savatenalinton 2017; Smith et al. 2018). Ma and Yu (2020) described the second species of Pseudocypretta, P. lineata, from Hanan Island, southern China. Both Pseudocypretta species were reported from similar habitats such as wetlands, ponds, steams, rice fields, and generally in association with aquatic macrophytes. The same is observed for Pseudocypretta amor sp. nov., which is commonly associated with aquatic macrophytes but also occurs in sediment in rivers, open lakes, and backwaters in the four main Brazilian floodplains. The importance of aquatic macrophytes for (macro) invertebrates is well established, as these plants provide resources such as food, shelter and a substrate for reproduction for these organisms (Thomaz and Cunha 2010; Matsuda et al. 2015; Campos et al. 2017).

Janz (1997) reported on a fossil species, Pseudocypretta sp., from the oldest sediments of a Miocene (Tertiary) crater lake near Steinheim am Albuch (Germany). The accompanying ostracod fauna (Strandesia, Cyprinotus, ...) indeed indicate a warmer, maybe subtropical, climate in which Pseudocypretta species could have occurred. However, the single SEM figure of a lateral view of a carapace of this species (Janz 1997, plate 12, fig. 10) clearly indicates that this specimen belongs to a different genus. The specimen does show a triangular, highly arched shape, but the anterior overlap of the RV by the LV is much larger than in any of the recent species. Janz (loc. cit.) also mentioned that radial septa are visible through the closed valves, but clearly states that these are visible along the ventral margin, which is not the case in Pseudocypretta.

Expansion of the distribution area

There are at present 2330 subjective species of living non-marine ostracods, of which almost 90% are known from one zoogeographical region; only six species are presently known from at least six zoogeographical regions and can be considered truly cosmopolitan (Meisch et al. 2019). This, in spite of the fact that most species of at least the Cypridoidea (ca. 75% of all known species) have a combination of characters that would allow long-distance dispersion (LDD), namely the potential to reproduce asexually, the production of drought-resistant eggs and (mostly) the potential for free-swimming (McKenzie 1971; Horne and Martens 1998; Schön et al. 2018). Other, non-cypridoid species add brooding to the list of biological specialisations that would facilitate establishing populations after an LDD event (e.g., Darwinulidae, Timiriaseviinae). In spite of these apparent advantages, inter-continental LDD appears to be rare, although such events within zoogeographical regions might be more common, as was shown for a species complex in the genus Strandesia (Schön et al. 2018). The discovery of a new species of the genus Pseudocypretta, thus far thought to be typical of South East Asia and China, in the Neotropical region therefore constitutes a significant range expansion of the genus. However, it could be that Pseudocypretta is in fact a circumtropical genus, such as Stenocypris Sars, 1889, Cypretta Vávra, 1895 and others (Meisch et al. 2019). In that case, it would be expected that species of this genus could also be found in tropical Africa and Australia.

Comparative morphology of Pseudocypretta species

Of the three species presently assigned to Pseudocypretta, only P. lineata and P. amor sp. nov. have received extensive descriptions, illustrating most of the morphological characters presently deemed relevant in freshwater ostracod taxonomy. Although rather well-described and illustrated for its time, the description of P. maculata by Klie (1932) lacks several characters that would be needed to make a full comparative analysis of the three species. A redescription of the type species of the genus is therefore needed. Here, we will discuss several morphological characters relevant to the identity of the genus and the three congeneric species. A summary is given in table 2.

In all three species of Pseudocypretta, the LV overlaps the RV at least anteriorly and ventrally, whereas the valve overlap in Cypretta is inverse. Victor and Fernando (1979), Battish (1978 1982) and Neale (1984) have all identified specimens from South East Asia as P. maculata, but in their specimens, the RV was reported to overlap the LV frontally. These identifications are therefore doubtful and might concern species of Cypretta.

Marginal septa are calcified walls between the external lamella and the calcified internal lamellae of the valves, running through the vestibulum and thus strengthening the margins of the valves. They are not uncommon in several (related and unrelated) ostracod lineages, such as the genera Oncocypris G.W. Müller (1898) (Oncocypridinae De Deckker (1979) in Notodromadidae), Stenocypris Sars (1889) (Herpetocypridinae Kaufmann (1900) in Cyprididae) and closer to the present genus also Cypretta Vávra (1895) (Cyprettinae Hartmann (1963) in Cyprididae), Batucypretta Victor and Fernando (1981) (Batucyprettinae Victor and Fernando (1981) in Cyprididae), Bradycypris Sars (1925), Paracypretta Sars (1924), Zonocypretta De Deckker (1981) (Bradycypridinae Hartmann and Puri (1974) in Cyprididae) and Cyprettadopsis Savatenalinton (2020) (Cypridopsinae Kaufmann (1900) in Cyprididae).

For P. maculata, Klie (1932) illustrated septa in the RV (fig. 67), but not in the LV (fig. 66), and also only described them for the RV (“... die von Scheidewänden durchsetzt wird, sie lassen den Schalenrand radiär gestreift erscheinen.” –p. 485). Ma and Yu (2020) illustrated well-developed septa for the RV (fig. 6F), and incompletely developed ones for the LV (fig. 6G). The same pattern is true in P. amor sp. nov.: well developed septa in the RV, incompletely developed ones in the LV. It would thus appear that Klie (1932) missed the incompletely developed septa in the LV and that all three species could share this character.

The LV has an inner list which postero-ventrally runs straight and not parallel to the valve margin in all three species of Pseudocypretta (Klie 1932, fig. 66; Ma and Yu 2020, fig. 6c, present paper, Fig. 3A). This character is also apparent in some species of Cypridopsis Brady, 1867, most notably in Cypridopsis vidua (O.F. Müller, 1776).

Ma and Yu (2020, fig. 7B) illustrated claw G2 on the A2 of P. lineata as being much stronger serrated than the other claws, and Klie (1932, fig. 69) showed the same feature for P. maculata. This character is generally typical for the taxa in the tribe Zonocypridini Higuti and Martens, 2012, namely for the species in the genera Zonocypris G.W. Müller, 1898 and Cabelodopsis Higuti and Martens, 2012. However, Savatenalinton (2020) also illustrated such a strongly serrated claw G2 in the genus Cyprettadopsis Savatanalinton, 2020, albeit with a different appearance (see below).

In all three species, the second palp segment of the Mx1 is cylinder-shaped (rectangular in the drawings) and about twice as long as the basal width. Both P. lineata and P. amor sp. nov. have smooth tooth-bristles on the third endite. However, whereas Ma and Yu (2020, p. 216) indicate that P. maculata has serrated tooth-bristles, Klie (1932, p. 486) clearly states “...die beiden zahnartige verstärkten Borsten ungefiedert.” (both tooth-like enforced setae not serrated: ungefiedert = unfeathered). Therefore, all three species appear to have smooth tooth-bristles.

In all three species of Pseudocypretta, the penultimate segment of the T2 is undivided, while it is clearly divided in species of Cypretta. The presence or absence of setae d1 and d2 on T2 in P. maculata are unknown, but Ma and Yu (2020, fig. 8A) call the single seta on one of the basal segments of T2, seta d1. However, our interpretation is that this seta is clearly inserted on the ‘knee’ segment of this limb, in which case it is seta d2, just as in P. amor sp. nov. (Fig. 6E)

The third thoracopod (T3) is a walking leg in the Cytheroidea and the Darwinuloidea. Within the Cypridoidea, this leg is a cleaning leg with the tip of the third segment and the fourth segment fused into a pincer in the Cyprididae, whereas the third and the fourth segments are clearly separated in Candonidae (hence the name candonid type), Ilyocyprididae and Notodromadidae. However, there are clear exceptions in several lineages of Cypridoidea which have the candonid type T3. These are: Oncocypris G.W. Müller, 1898 and Neozonocypris Klie (1944) in the subfamily Oncocypridinae in the Notodromadidae Kaufmann (1900); Callistocypris Shornikov, 1980 in the Callistocypridinae Shornikov, 1980 (see also Pinto et al. 2005; Savatenalinton and Martens 2013); Cyprettadopsis and Neocypridopsis Klie (1940) in the Cypridopsinae Kaufmann (1900); Batucypretta in the Batucyprettinae and Pseudocypretta in the Cyprettinae, all in the Cyprididae. The wider taxonomic significance of this phenomenon will be discussed elsewhere, but the significance for the genus Pseudocypretta is further explained below. The enigmatic Batucypretta needs urgent redescription. Ma and Yu (2020) briefly described what they call a different species from Batucypretta from Hanan Island (southern China), but from their illustrations it is clear that these are specimens of Cyprettadopsis sutura Savatenalinton (2020). Ma and Yu (2020) could not have been aware of this species as their paper was published on April 24th, 2020, while the paper Savatenalinton (2020) was published only 3 days earlier, on April 21st, 2020. This was the first time that C. sutura Savatenalinton (2020) was reported outside of Thailand.

A flagellar caudal ramus has been reported for P. maculata and P. lineata. In both cases, the CR is small, has a short lateral seta, while the ramus is distally fused with the terminal claw. In Pseudocypretta amor sp. nov. it was not possible to clearly observe a structure that resembles the CR, despite a long series of dissections. This leads us to decide that this structure is either fully absent in Pseudocypretta amor sp. nov., or so small that it is undetectable. Klie (1932) described the CR on P. maculata as small and flagellum-like and difficult to observe. In P. lineata, the CR has the same morphology as in P. maculata but is not so small. Based on the illustrations by Ma and Yu (2020, fig. 8B) it has almost the same length as the T2 (fig. 8A). This could be an error of scale, but it should be re-checked as it is unlikely.

Taxonomic position of Pseudocypretta

Klie (1932) compared his new genus to genera from Cypridopsinae because of the reduced CR (including at that stage also Oncocypris, this genus is now in the Notodromadidae, but see below), as well as to genera with marginal septae such as Cypretta, Paracypretta and Bradycypris, but offered no clear opinion as to where to lodge his new genus in a taxonomic classification. Hartmann and Puri (1974) listed Pseudocypretta in the Cypridopsinae, without further discussion. McKenzie (1982a, footnote pp. 768–769) wrote:

“Pseudocypretta has a smooth shell, the inner lamella bears radial septa (in the right valve only), the maxillule 3rd lobe has 2 Zahnborsten, the furca is reduced as in other cypridopsids. Because the shell bears radial septa, this genus is considered to be transitional to the family Cyprettidae, in which all known genera have such septa. On these grounds, Pseudocypretta likewise merits its own subfamily, herein named Pseudocyprettinae, new subfamily.”

Meanwhile, the family Cyprettidae cited by McKenzie (loc. cit.) is lowered to the rank of subfamily within the family Cyprididae, in which Pseudocypretta is included (Martens and Savatenalinton 2011; Meisch et al. 2019) and the subfamily Pseudocyprettinae has not been recognized in any global taxonomic overview of freshwater ostracods.

Karanovic (2012) mentioned the genus Pseudocypretta in a brief remark, while discussing the subfamily Oncocypridinae (in Notodromadidae), and by making a brief comparison to Neozonocypris). She concluded that the position of Pseudocypretta is doubtful and that it needs further clarification.

Savatenalinton (2020), while describing the new genus Cyprettadopsis, extensively discussed the characters mentioned above (valve overlap, T3, CR, etc.), but mostly in comparison with what she called “the Cypretta-group” (Cypretta, Batucypretta, etc.), with several genera of Cypridopsinae and briefly with the two genera in the Oncocypridinae, but only mentioned Pseudocypretta in passing, in spite of the fact that both taxa are quite similar (see differential diagnosis above and Table 4).

Table 4.

Comparative morphology of Pseudocypretta, Cyprettadopsis and Cypretta (mainly based on Klie (1932); Ma and Yu (2020); Savatenalinton (2018 2020); present paper and various other descriptions of Cypretta species)

graphic file with name zoolstud-61-077-t005.jpg

Open in a new tab

Pseudocypretta differs from Cypretta in a number of important characters, such as the anterior valve overlap, the fact that the LV has only incompletely developed marginal septa, the shape of the posteroventral inner list in the LV, the absence of seta d on T1, of seta d1 on T2, the separate segment 4 on the T3 and the highly reduced CR. On the other hand, in almost all of these characters, Pseudocypretta agrees with the morphology of Cyprettadopsis. Differences between the two genera are listed above in the differential diagnosis but are far less important than the differences between both of these genera and Cypretta.

By previously lodging Pseudocypretta in the Cyprettinae together with Cypretta, priority was clearly given to the stability of the presence of marginal septa over the fact that the CR in the two genera is so very different. Admittedly, several species of Cypretta also have a CR which is already partly reduced from the basic cypridid pattern with setae or claws reduced or missing. In Candonidae, several closely related lineages show progressive reduction of the CR (Karanovic 2007), although this is mostly linked to subterranean or even interstitial life, which causes the simplification of limb chaetotaxy (see Danielopol 1978 and a partial revision in Martens 1992).

However, there are indications that in the present case, maybe the reduced CR is more stable and a more reliable character on which to base classifications. The following arguments should be considered.

(1) Marginal septa occur in various ostracod lineages, some closely, some only distantly related. They are certainly subject to parallel evolution within the Ostracoda (see above).

(2) Cyprettadopsis, a genus quite similar to Pseudocypretta with both marginal septa and a flagellar CR, was lodged in a separate tribe in the Cypridopsinae, thus giving priority to the flagellar CR over the presence of marginal septa.

(3) The genus Neocypridopsis Klie (1940) also has a separate fourth segment in the T3 and a flagellar CR and is lodged in the Cypridopsini of the Cypridopsinae. Karanovic and Datry (2009) extensively redescribed Neocypridopsis albida (Sars, 1901), and, based on that detailed morphology, maintained the genus in the Cypridopsinae. Karanovic (2012) transferred the genus Neocypridopsis to the Oncocypridinae in the Notodromadidae, based on the whip-like CR and the separated fourth segment on the T3, but without demonstrating that it possesses the most important features of the family and subfamily, namely the separated, not fused, eyes with separate eye tubercles and the presence of four (not two) serrated teeth bristles on the third endite of the Mx1 (De Deckker 1979). We here maintain Neocypridopsis in the Cypridopsinae, albeit maybe not with all species presently allocated to it and not necessarily within the tribe Cypridopsini.

Based on the above arguments, we here assign Pseudocypretta to the tribe Cyprettadopsini. Savatenalinton (2020) extensively discussed the taxonomic consequences of lodging Cyprettadopsis, with both complete and incompletely developed marginal septa, in the Cypridopsinae, and all the arguments (for and against) she discussed are also valid for Pseudocypretta, so we will not repeat them here, just add one additional remark.

Savatenalinton (2020) is correct in making a distinction between the much larger and more heavily serrated claw G2 on A2 which is typical of the Zonocypridini (Cabelodopsis and Zonocypris s.s.) and the moderately enlarged claw G2 with a different type of serration as in Cyprettadopsis and Pseudocypretta, but also in some (mostly unornamented) species of Zonocypris s.l. The fact that the genus Zonocypris is not a monophyletic genus was already foreshadowed by Higuti and Martens (2012). Díaz and Martens (2018) also questioned the position of the Oncocypridinae in the Notodromadidae, as did Karanovic (2012 –see above) and Savatanalinton (2020), but it remains unclear if moving this taxon as a tribe in the Cypridopsinae is really the solution. Maybe acknowledging that Oncocypris G.W. Müller, 1898 (with 4–5 teeth bristles on the third endite of the Mx1, a 5-segmented A2 and eye tubercles on the carapace) and Neozonocypris Klie (1944) (with 2 teeth bristles, a 4-segmented A2 and no eye tubercles) (Savatenalinton 2015) do not belong in the same subfamily would be the beginning of a solution.

This seemingly small taxonomic change (moving one genus from one subfamily to another within the same family) might, however, have a nomenclatorial consequence. If Pseudocypretta is lodged into the Cyprettadopsini, then Pseudocyprettinae McKenzie (1982a) would, lowered to the rank of tribe to fit the present taxonomy of Meisch et al. (2019), become a senior synonym of Cyprettadopsini. However, since the International Code of Zoological Nomenclature (ICZN) does not offer rulings for taxa above the genus-level (only recommendations), we here propose to consider the ill-described and never used subfamily Pseudocyprettinae as an unused senior synonym of Cyprettadopsini Savatenalinton (2020). To list the extensively described Cyprettadopsini as a synonym of Pseudocyprettinae would not be in the interest of taxonomic stability.

There are now five lineages with the candonid type T3 in the Cypridoidea, namely one lineage in the Notodromadidae (two genera in the Oncocypridinae— see above) and four lineages in the Cyprididae (three genera in two tribes in the Cypridopsinae, one genus in the Callistocypridinae and one in the Batucyprettinae).

CONCLUSIONS

McKenzie (1982b) already described several examples in ostracod taxonomy where “homeomorphy is a persistent joker in the taxonomic pack”. Parallel and convergent evolution is known from many animal groups, and ostracods are no exception. It would appear from the above discussion that, for some of the often-used characters in ostracod taxonomy (valve overlap, marginal septa in valves, terminal segment on T3 of the candonid type or with a pincer, CR of the cypridopsine type, reduced to flagellum or not, etc.) there is clear evidence of parallel evolution. This leads to a mosaic of characters and character states, and it is the task of the taxonomist to bring order into this chaos, preferably by translating phylogenetic evolution into taxonomic classifications.

The present description of a new species of the previously South East Asian genus Pseudocypretta has allowed us to discuss the relevance of several morphological characters in the taxonomy of cypridoid taxa with a candonid type T3. Given the mosaic development of characters and character states in the Cypridoidea resulting from homeomorphy and parallel morphological evolution in different lineages, an integrated taxonomic approach, combining morphological and molecular approaches, is the way forward. Hopefully, the advancements in genomic techniques will overcome the difficulties thus far encountered with single genetic marker approaches in the Cyprididae, which never provided a good resolution of the various genera and subfamilies in this family.

Acknowledgments

This work and the new species name were registered with ZooBank under urn:lsid:zoobank.org:pub:778840A4-8302-4295-8C67-E4EEDE4CD2C1. This research results from projects funded by National Council for Scientific and Technological development (CNPq) and Fundação Araucária through the National System of Biodiversity Research (SISBIOTA –coordinated and led by Prof. Dr. Fábio Amodêo Lansac-Tôha and Dr. Luiz Felipe Machado Velho), Programa de Pesquisa Ecológica de Longa Duração (PELD-PIAP, sitio 6) programs, projects n°472434/03-9, 478487/2010-0, 476130/2010-7, 478629/2012-5, SETI/Fundação Araucária/MCT/CNPq (n°232/10), and Academic Excellence Program (PROEX)/Coordination for the Improvement of Higher Education Personnel (CAPES). We thank the Graduate Program in Ecology of Inland Water Ecosystems (PEA) and the Centre of Research in Limnology, Ichthyology and Aquaculture (Nupélia) of the State University of Maringá (UEM) for the logistic support. We thank present and past ostracodologist students of Nupélia’s laboratory for helping to sort the samples and Julien Cillis and Laetitia Despontin (Brussels, Belgium) for technical assistance with the SEM. VGF and NMA would like to thank CAPES and CNPq for granting their scholarship, respectively. VGF would like to thank CAPES for his doctoral sandwich scholarship –Financial code 001. JH acknowledges CNPq for the research productivity grant. The State University of Maringá (UEM, Maringá) and the Royal Belgian Institute of Natural Sciences (RBINS, Brussels) have a bilateral Memorandum of Understanding regarding collaborative Scientific Research.

List of abbreviations

AMA

Amazon River floodplain.

ARA

Araguaia River floodplain.

PAN

Pantanal.

PAR

Paraná River floodplain.

RV

right valve.

LV

left valve.

LVi

left valve inner view.

RVi

right valve inner view.

Cp

carapace.

CpLl

carapace left lateral view.

CpRl

carapace right lateral view.

CpD

carapace dorsal view.

CpV

carapace ventral view.

CpFr

carapace frontal view.

L

length.

H

height.

W

width.

A1

antennula.

R

Rome organ.

WO

Wouters organ.

A2

antenna.

CR

caudal ramus.

MdPalp

mandibular palp.

MdCox

mandibular coxa.

Mx1

maxillula.

T1

first thoracopod.

T2

second thoracopod.

T3

third thoracopod.

Footnotes

Authors’ contributions: All authors sampled and analyzed the material; VGF and NMA dissected and illustrated the specimens. All authors helped with the delimitation of the species. All authors wrote the manuscript and approved the final manuscript.

Competing interests: All authors declare that they have no competing interests.

Availability of data and materials: Available type material, as well as other illustrated material, of the new species is described in the text.

Consent for publication: All the authors consent to the publication of this manuscript.

Ethics approval consent to participate: No ethics approval is required for this research. The necessary permits to conduct the fieldwork were obtained by the authors.

References

  1. Almeida NM, Higuti J, Ferreira VG, Martens K. 2021. A new tribe, two new genera and three new species of Cypridopsinae (Crustacea, Ostracoda, Cyprididae) from Brazil. Eur J Taxon 762:1–48. doi:10.5852/ejt.2021.762.1451.
  2. Agostinho AA, Thomaz SM, Gomes LC. 2004. Threats for biodiversity in the floodplain of the Upper Paraná River: effects of hydrological regulation by dams. Ecohydrol Hydrobiol 4:255–256.
  3. Baird W. 1845. Arrangement of the British Entomostraca, with a list of species, particularly noticing those which have as yet been discovered within the bounds of the Club. Trans Berwicks Nat Club 2:145–158.
  4. Balian E, Segers H, Lévèque C, Martens K. 2008. The freshwater animal diversity assessment: an overview of the results. Hydrobiologia 595:627–637. doi:10.1007/s10750-007-9246-3.
  5. Barros V, Chamorro L, Coronel G, Baez J. 2004. The major discharge events in the Paraguay River: Magnitudes, source regions, and climate forcings. J Hydrometereol 5:1161–1170. doi:10.1175/JHM-378.1.
  6. Battish SK. 1978. Record of Pseudocypretta Klie, 1933 and Tanycypris Triebel, 1959 (Crustacea: Ostracoda) from India. Curr Sci India 47:247–248.
  7. Battish SK. 1982. Freshwater Ostracods of the family Cypridopsidae from Punjab, India, with the description of two new species. J Nat Hist 16:83–94. doi:10.1080/00222938200770061.
  8. Brady GS. 1867. A synopsis of the recent British Ostracoda. Intell Obs 12:110–130.
  9. Broodbakker NW, Danielopol DL. 1982. The chaetotaxy of Cypridacea (Crustacea, Ostracoda) limbs: proposals for a descriptive model. Bijdr Dierk 52:103–120. doi:10.1163/26660644-05202003.
  10. Campos R, Conceicão EO, Pinto MBO, Bertoncin APS, Higuti J, Martens K. 2017. Evaluation of quantitative sampling methods in pleuston: an example from ostracod communities. Limnologica 63:36–41. doi:10.1016/j.limno.2017.01.002.
  11. Campos R, Lansac-Tôha FM, Conceição EO, Martens K, Higuti J. 2018. Factors affecting the metacommunity structure of periphytic ostracods (Crustacea, Ostracoda): a deconstruction approach based on biological traits. Aquat Sci 80:1–12. doi:10.1007/s00027-018-0567-2.
  12. Campos R, Rosa J, Ferreira VG, Conceicão EO, Martens K, Higuti J. 2021. Macrophyte life forms influence the effects of environmental and spatial factors on the beta-diversity of associated ostracod communities (Crustacea). Aquat Sci 83:1–15. doi:10.1007/s00027-021-00777-9.
  13. Cohuo-Durán S, Elías-Gutiérrez M, Karanovic I. 2013. On three new species of Cypretta Vávra, 1895 (Crustacea: Ostracoda) from the Yucatan Peninsula, Mexico. Zootaxa 3636:501–524. doi:10.11646/zootaxa.3636.4.1. . [DOI] [PubMed]
  14. Danielopol DL. 1978. Über Herkunft und Morphologie der Süsswasser-hypogäischen Candonina (Crustacea, Ostracoda). Sitzber Preuss Akad 187:1–162.
  15. De Deckker P. 1979. Comparative morphology and review of Australian Notodromadinae Kaufmann, 1900 (Crustacea, Ostracoda). Senckenb Biol 59:417–463.
  16. De Deckker P. 1981. Taxonomic notes on some Australian ostracods with description of new species. Zool Scr 10:37–55. doi:10.1111/j.1463-6409.1981.tb00483.x.
  17. Díaz A, Martens K. 2018. On Argentodromas bellanella gen. nov., sp. nov. (Crustacea, Ostracoda) from a stream in northeastern Argentina (South America). Zool Stud 57:10. doi:10.6620/ZS.2018.57-10. . [DOI] [PMC free article] [PubMed]
  18. Ferreira VG, Higuti J, Martens K. 2019. A striking case of convergent evolution in two species of Cypricercinae (Crustacea, Ostracoda), with the description of a new genus and species from Brazil. Zool Anz 283:1–11. doi:10.1016/j.jcz.2019.06.007.
  19. Ferreira VG, Higuti J, Martens K. 2020. Taxonomic revision of Strandesia s.s. (Crustacea, Ostracoda) from four Brazilian floodplains, with the description of three new species. Zootaxa 4760:1–74. doi:10.11646/zootaxa.4760.1.1. . [DOI] [PubMed]
  20. Harris MB, Tomas W, Mourao G, Silva CJ, Guimaraes E, Sonoda F, Fachim E. 2005. Safeguarding the Pantanal wetlands: threats and conservation initiatives. Conserv Biol 19:714–720. doi:10.1111/j.1523-1739.2005.00708.x.
  21. Hartmann G. 1963. Zur Phylogenie und Systematik der Ostracoden. Zeitschr Zool Syst Evolutionsforsch 1 (1-2):1–154.
  22. Hartmann G, Puri HS. 1974. Summary of neontological and paleontological classification of Ostracoda. Mitt Hamb Zool Mus Inst 70:7–73.
  23. Higuti J, Conceição EO, Campos R, Ferreira VG, Rosa J, Pinto MBO, Martens K. 2017a. Periphytic community structure of Ostracoda (Crustacea) in the river-floodplain system of the Upper Paraná River. Acta Limnol Brasil 29:e120. doi:10.1590/S2179-975X12217.
  24. Higuti J, Declerck SA, Lansac-Tôha FA, Velho LFM, Martens K. 2010. Variation in ostracod (Crustacea, Ostracoda) communities in the alluvial valley of the upper Paraná River (Brazil) in relation to substrate. Hydrobiologia 644:261–278. doi:10.1007/s10750-010-0122-1.
  25. Higuti J, Lansac-Tôha FA, Velho LFM, Martens K. 2009. Biodiversity of non-marine ostracods (Crustacea, Ostracoda) in the alluvial valley of the upper Paraná River, Brazil. Braz J Biol 69:661–668. doi:10.1590/S1519-69842009000300020. . [PubMed]
  26. Higuti J, Martens K. 2012. On a new Cypridopsine genus (Crustacea, Ostracoda, Cyprididae) from the Upper Paraná River Floodplain (Brazil). Zootaxa 3391:22–38. doi:10.11646/zootaxa.3391.1.2.
  27. Higuti J, Roche KF, Martens K. 2017b. Checklist of freshwater ostracods (Crustacea, Ostracoda) of the Pantanal of Mato Grosso do Sul, Brazil. Iheringia Ser. Zool 107, supl. doi:10.1590/1678-4766e2017114.
  28. Higuti J, Schön I, Audenaert L, Martens K. 2013. On the Strandesia obtusata/elliptica lineage (Ostracoda, Cyprididae) in the alluvial valley of the upper Paraná River (Brazil), with the description of three new species. Crustaceana 86(2):182–211. doi:10.1163/15685403-00003160.
  29. Horne DJ, Cohen A, Martens K. 2002. Taxonomy, morphology and biology of quaternary and living Ostracoda. In: Holmes AJ, Chivas AR (ed) The Ostracoda: Applications in Quaternary Research. Geophysical Monograph Series, Washington. doi:10.1029/131GM02.
  30. Horne DJ, Martens K. 1998. An assessment of the importance of resting eggs for the evolutionary success of non-marine Ostracoda (Crustacea). Arch Hydrobiol 52:549–561.
  31. Janz H. 1997. Die Ostracoden der kleini-Schichten des miozänen Kratersees von Steinheim am Albuch (Süddeutschland). Stuttg Beitr Naturk, Serie B 251:1–101.
  32. Junk WJ, Piedade MTF, Schöngart J, Cohn-Haft M, Adeney JM, Wittmann F. 2011. A classification of major naturally-occurring Amazonian lowland wetlands. Wetlands 31:623–640. doi:10.1007/s13157-011-0190-7.
  33. Karanovic I. 2007. Candoninae (Ostracoda) from the Pilbara Region in Western Australia. Crusteana Monographs. Brill, Boston, USA.
  34. Karanovic I. 2012. Recent Freshwater Ostracods of the World: Crustacea, Ostracoda, Podocopida. Springer Verlag, Berlin-Heidelberg, Germany.
  35. Karanovic I, Datry T. 2009. Overview of Candoninae (Crustacea, Ostracoda) of South America and the West Indies, with the description of two new species and one new genus. Zootaxa 2267:1–25. doi:10.11646/zootaxa.2267.1.1.
  36. Karuthapandi M, Rao DV, Innocent BX. 2014. Freshwater Ostracoda (Crustacea) of India -a checklist. J Threat Taxa 6:6576–6581. doi:10.11609/JoTT.o3682.6576-81.
  37. Kaufmann A. 1900. Cypriden und Darwinuliden der Schweiz. Rev Suisse Zool, Ann Soc Zool Suisse 8:209–423.
  38. Klie W. 1932. Die Ostracoden der deutschen limnologischen sunda-expedition. Archiv Hydrobiol 11:447–502.
  39. Klie W. 1940. Süßwasser-Ostracoden aus Nordostbrasilien. 6: Cyprinae mit geißelförmiger Furka. Zool Anz 130:59–73.
  40. Klie W. 1944. Ostracoda. Exploration du Parc National Albert, Mission H. Damas (1935–1936) 12:1–62.
  41. Latreille PA. 1802. Histoire naturelle, générale et particulière des Crustacés et des Insectes. Familles Naturelles des Genres. Dufart, Paris, France.
  42. Latrubesse EM, Amsler ML, Morais RP, Aquino S. 2009. The geomorphologic response of a large pristine alluvial river to tremendous deforestation in the South American tropics: The case of the Araguaia River. Geomorphology 113:239–252. doi:10.1016/j.geomorph.2009.03.014.
  43. Ma S, Yu NA. 2020. Freshwater ostracods (Crustacea) from Hainan Island, southern China, with description of a new species. Zootaxa 4767:201–243. doi:10.11646/zootaxa.4767.2.1. . [DOI] [PubMed]
  44. Martens K. 1987. Homology and functional morphology of the sexual dimorphism in the antenna of Sclerocypris Sars, 1924 (Crustacea, Ostracoda, Megalocypridinae). Bijdr Dierk 57:183–190. doi:10.1163/26660644-05702003.
  45. Martens K. 1992. On Namibcypris costata n. gen. n. sp. (Crustacea, Ostracoda, Candoninae) from a spring in northern Namibia, with the description of a new tribe and a discussion on the classification of the Podocopina. Stygologia 7:27–42.
  46. Martens K, Savatenalinton S. 2011. A subjective checklist of the Recent, free-living, non-marine Ostracoda (Crustacea). Zootaxa 2855:1–79. doi:10.11646/zootaxa.2855.1.1.
  47. Matsuda JT, Lansac-Tôha FA, Martens K, Velho LFM, Mormul RP, Higuti J. 2015. Association of body size and behavior of freshwater ostracods (Crustacea, Ostracoda) with aquatic macrophytes. Aquat Ecol 49:321–331. doi:10.1007/s10452-015-9527-2.
  48. McKenzie KG. 1971. Palaeozoogeography of freshwater Ostracoda. Bull Cent Rech Pau 5:207–237.
  49. McKenzie KG. 1982a. Island, with a key to the Cypridopsinae. Proc Biol Soc Wash 95:766–771.
  50. McKenzie KG. 1982b. Homeomorphy: Persistant joker in the taxonomic pack, with the description of Bradleycypris gen. nov. In: Bate RH, Robinson E and Sheppard LM (eds) Fossil and Recent Ostracods. Ellis Horwood Ltd, Chichester.
  51. Meisch C. 2000. Freshwater Ostracoda of western and central Europe. Spektrum Akademischer Verlag GmbH, Heidelberg, Germany.
  52. Meisch C, Smith RJ, Martens K. 2019. A subjective global checklist of the extant non-marine Ostracoda (Crustacea). Eur J Taxon 492:1–135. doi:10.5852/ejt.2019.492.
  53. Müller GW. 1898. Ergebnisse einer zoologischen Forschungsreise in Madagaskar und Ost-Afrika 1889–1895 von Dr. A. Voeltzkow: Die Ostracoden. Abhandlungen der Senckenbergischen Naturforschenden Gesellschaft 21:255–296.
  54. Müller OF. 1776. Zoologiae danicae Prodromus, seu Animalium daniae et norvegiae indigenarum Characteres, Nomina, et Synonyma imprimis popularium, I–XXXXII:1–282.
  55. Neale JW. 1984. The freshwater Ostracoda. In: Fernando CH (ed) Ecology and Biogeography in Sri Lanka. Springer, Dordrecht, Netherlands.
  56. Pereira LC, Lansac-Tôha FA, Martens K, Higuti J. 2017. Biodiversity of ostracod communities (Crustacea, Ostracoda) in a tropical floodplain. Inland Waters 7:323–332. doi:10.1080/20442041.201 7.1329913.
  57. Pinto RL, Rocha CEF, Martens K. 2003. On two new species of the genus Vestalenula Rossetti and Martens, 1998 (Crustacea, Ostracoda, Darwinulidae) from semiterrestrial habitats in São Paulo State (Brazil). Zool J Linn Soc Lond 139:305–313. doi:10.1046/j.1096-3642.2003.00070.x.
  58. Pinto RL, Rocha CEF, Martens K. 2005. On new terrestrial ostracods (Crustacea, Ostracoda) from Brazil, primarily from São Paulo State. Zool J Linn Soc 145:145–173. doi:10.1111/j.1096-3642. 2005.00185.x.
  59. Sars GO. 1866. Oversigt af Norges marine ostracoder. Forh Vidensk-Selsk Christiania 1865:1–130.
  60. Sars GO. 1889. On some freshwater Ostracoda and Copepoda, raised from dried Australian mud. Christiania Videnskabs-Selskabs Forhandlinger 8:3–79.
  61. Sars GO. 1901. Contributions to the Knowledge of the Freshwater Entomostraca of South America: As Shown by Artificial Hatching from Dried Material. Part II: Copepoda-Ostracoda. Arch Math Nat Vid. 24(1):1–46.
  62. Sars GO. 1924. The freshwater Entomostraca of the Cape Province (Union of South Africa). Ostracoda. Ann S Afr Mus 20:105–193.
  63. Sars GO. 1925. An account of the Crustacea of Norway with short descriptions and figures of all the species. In: Sars GO (ed) Ostracoda. Christiania, A. Cammermeyer, Copenhagen.
  64. Savatenalinton S. 2014. Ostracods (Crustacea: Ostracoda) from the floodplain of the Chi River, Mahasarakham Province, Northeast Thailand, with the first record of male Tanycypris siamensis Savatenalinton and Martens, 2009. Zootaxa 3838:195–206. doi:10.11646/zootaxa.3838.2.4. [DOI] [PubMed]
  65. Savatenalinton S. 2015. On three new species of non-marine ostracods (Crustacea: Ostracoda) from Northeast Thailand. Zootaxa 3914:275–300. doi:10.11646/zootaxa.3914.3.3. [DOI] [PubMed]
  66. Savatenalinton S. 2017. Species diversity of ostracods (Crustacea: Ostracoda) from rice fields in Northeast Thailand, with the description of a new Tanycypris species. Zootaxa 4362:499–516. doi:10.11646/zootaxa.4362.4.2. . [DOI] [PubMed]
  67. Savatenalinton S. 2018. Two new species of Cypretta Vávra, 1895 (Crustacea, Ostracoda) from Thailand and discussion of the genus. Zootaxa 4532:483–502. doi:10.11646/zootaxa.4532.4.2. . [DOI] [PubMed]
  68. Savatenalinton S. 2020. A new cypridopsine genus (Crustacea, Ostracoda) from Thailand. Eur J Taxon 631:1–16. doi:10.5852/ejt.2020.631.
  69. Savatenalinton S, Martens K. 2009. Generic revision of Cypricercinae McKenzie, 1971 (Crustacea, Ostracoda), with the description of three new genera and one new species and a phylogenetic analysis of the subfamily. Hydrobiologia 632:1–48. doi:10.1007/s10750-009-9826-5.
  70. Savatenalinton S, Martens K. 2010. On the subfamily Cypricercinae McKenzie, 1971 (Crustacea, Ostracoda) from Thailand, with the description of six new species. Zootaxa 2379:1–77. doi:10.11646/zootaxa.2379.1.1.
  71. Savatenalinton S, Martens K. 2013. On Callistocypris thailandensis sp. nov. (Ostracoda, Crustacea) from Thailand. Zootaxa 3686:578–586. doi:10.11646/zootaxa.3686.5.6. . [DOI] [PubMed]
  72. Savatenalinton S, Palero F, Mesquita-Joanes F. 2022. Revision of the taxonomic position of Pseudocypretta Klie, 1932 (Ostracoda: Cyprididae), with a redescription of P. maculata Klie, 1932. J Crust Biol 42:ruac031. doi:10.1093/jcbiol/ruac031.
  73. Savatenalinton S, Suttajit M. 2016. A checklist of recent non-marine ostracods (Crustacea: Ostracoda) from Thailand, including descriptions of two new species. Zootaxa 4067:1–34. doi:10.11646/zootaxa.4067.1.1. . [DOI] [PubMed]
  74. Schön I, Higuti J, Patel T, Martens K. 2018. Aquatic long-distance dispersal and vicariance shape the evolution of an ostracod species complex (Crustacea) in four major Brazilian floodplains. Mol Phylogen Evol 121:86–97. doi:10.1016/j.ympev.2017.12.019. . [DOI] [PubMed]
  75. Shornikov E. 1980. Ostracodes in terrestrial biotopes. Zool Zhurn 59:1309–1319. (in Russian with English abstract)
  76. Smith RJ, Zhai D, Savatenalinton S, Kamiya T, Yu N. 2018. A review of rice field ostracods (Crustacea) with a checklist of species. J Limnol 77:1–16. doi:10.4081/jlimnol.2017.1648.
  77. Thomaz SM, Cunha ER. 2010. The role of macrophytes in habitat structuring in aquatic ecosystems: methods of measurement, causes and consequences on animal assemblages’ composition and biodiversity. Acta Limnol 22:218–236. doi:10.4322/actalb.02202011.
  78. Vávra W. 1895. Die von Dr. F. Stuhlmann gesammelten Süsswasser-Ostracoden Zanzibar’s. Jahrb Hamb Wiss Anst 12:3–23.
  79. Victor R, Fernando CH. 1979. The freshwater ostracods (Crustacea: Ostracoda) of India. Rec Zool Surv India 74:147–242.
  80. Victor R, Fernando CH. 1981. Freshwater Ostracods (Crustacea: Ostracoda) of the genus Cypretta Vávra, 1895 from Malaysia, Indonesia and the Philippines. Int Rev Ges Hydrobiol 66:415–433. doi:10.1002/iroh.19810660312.

Articles from Zoological Studies are provided here courtesy of Biodiversity Research Center, Academia Sinica

RESOURCES