European Journal of Taxonomy 193: 1-35

http://dx.doi.org/10.5852/ejt.2016.193

This work is licensed under a Creative Commons Attribution 3.0 License.

ISSN 2118-9773

www. europeanj ournaloftaxonomy. eu

2016 • Aiello G. et al.

Research article

urn:lsid:zoobank.org:pub:046A4DBB-702E-4261-86E3-DA0DB690B162

Intra- and interspecific shell variability of the genus

Urocythereis Ruggieri, 1950 (Ostracoda: Hemicytheridae)

in the La Strea Bay (Ionian Sea, Italy)

Giuseppe AIELLO 1 *, Diana BARRA 2 , Roberta PARISI 3

1 ’ 2 3 Dipartimento di Scienze della Terra, delEAmbiente e delle Risorse, Universita degli

Studi di Napoli Federico II, Largo San Marcellino 10, 80138 Napoli, Italy.

"Corresponding author: aie6411o@hotmail. com

2 Email: dibarra@unina it

’Email: [email protected]

1 urn: Isid :zoobank. org: author :DBCEA76E-42E4-4899-ABF C-98 84160E6FB1

2 urn:lsid:zoobank.org:author:6D83D636-3FAF-4247-BF51-ABF7AADO1434

3 um:lsid:zoobank.org:author:15FA09D2-9ED6-4314-87EA-8750D4F75BF4

Abstract. The variability of the reticulum pattern, ornamentation and outline of the Urocythereis

populations of the La Strea Bay is analysed. The results show that the shell features of the form

U. distinguenda (Neviani, 1928) (= U. oblonga Brady, 1866) have to be included within the high

variability range of U. margaritifera (G.W. Muller, 1894). Consequently, it is suggested that in the

upper infralittoral waters of the inlet two (and not three, as stated in previous investigations) species of

the genus Urocythereis presently live. A second form, displaying a relatively low variability, is described

as a new species, U. ilariae sp. nov.

Keywords. Intraspecific variability, shell morphology, Urocythereis , celation, outline analysis.

Aiello G., Barra D. & Parisi R. 2016. Intra- and interspecific shell variability of the genus Urocythereis Ruggieri,

1950 (Ostracoda: Hemicytheridae) in the La Strea Bay (Ionian Sea, Italy). European Journal of Taxonomy 193:

1-35. http://dx.doi.org/10.5852/eit.2016.193

Introduction

During a study of the Recent ostracods of the La Strea Bay more than two thousand valves of Urocythereis

were collected and assigned to three species (Aiello et al. 2006). Most specimens were assigned to

U. margaritifera (G.W. Muller, 1894) and U. distinguenda (Neviani, 1928), while a third form was left

in open nomenclature and named Urocythereis sp. 1.

The presence of shells exhibiting transitional characters between the former two species (then included

in U. margaritifera) indicated an unsolved taxonomic issue. For a correct evaluation of the degree of

intraspecific variability in Urocythereis , we have re-examined sub-recent specimens recovered in this

relatively small (length: 2,5 km, maximum width: 1 km) inlet, also known as Porto Cesareo Lagoon. It

European Journal of Taxonomy 193: 1-35 (2016)

is in its northern part connected with the Ionian Sea, and is characterised by a subtropical biocoenosis

(Parenzan 1976, 1983, 1984). The environmental setting is entirely included in the upper part of the

infralittoral zone, with water depth not exceeding five meters. Ecological parameters vary over seasons

and sectors of the bay (Fig. 1).

It can be supposed that environmental factors influence, at least in part, the development of different

shell morphs. Consequently, the studied specimens may represent slightly different ecomorphotypes

belonging to dead assemblages.

Fig. 1 . Location map of the study area and sampling stations and range of selected physico-chemical

parameters of the La Strea Bay (data from Belmonte & Rubino 1988; Mercurio et al. 2000; Gherardi

et al. 2001).

AIELLO G. et al., Shell variability of Urocythereis in the La Strea Bay (Italy)

With the aim to minimize the unavoidable taxonomist’s subj ectivity, we have employed two morphological

methods of discrimination: the first is the comparison of ornament morphology, taking into account the

features of the reticulation especially; the other is the morphometric analysis of the outline by means of

the computer program Morphomatica (Linhart et al. 2006).

To be more precise, our intent is: 1) to define intrademic, non-polytypic ( sensu Sylvester-Bradley 1976)

variations of shell features, namely the morphological variability of the Urocythereis demes - panmictitc

populations (freely interbreeding, sharing the same gene pool, relatively confined) of the La Strea Bay;

2) to assess how many Urocythereis species are present in the Recent/sub-Recent thanatocoenoses of the

bay; we consider this attempt as a step toward a better understanding of the complex morphology of the

genus from a paleontological viewpoint; 3) to characterize groups of fossae, stable within species and

variable among species (e.g., Al-Furaih 1977).

Intraspecific variability in ostracod shells

The studies on intraspecific morphological variations include investigations on soft parts (i.a., Rossetti

& Martens 1996; Martens et al. 1998; Yin et al. 1999), internal features of smooth valves (i.a., Aiello

et al. 2007, and references therein), surface ornamentation (i.a.. Keen 1982; Peypouquet et al. 1988;

Neil 2000) and outline (Baltanas & Danielopol 2011, and references therein). Intraspecific variability

can be continuous or discontinuous, and continuous variations may seem very simple to analyse if

compared with polymorphism sensu Lord (1940), that is “the occurrence together in the same locality

of two or more discontinuous forms of a species in such proportions that the rarest of them cannot be

maintained merely by recurrent mutation” (see Clark 1976 for discussion and extensive references).

Yet, when we deal with morphologically highly variable taxa, also non-polymorphic species highlight

complex taxonomic problems.

Here, we focus on the continuous variation of shape and ornament in Urocythereis, with special regard

to reticulation. Urocythereis species may show all five types of continuous variation of fine sculpture (in

position, form, strength of expression, size and number of elements) described by Liebau (1971).

High-degree variability in ostracod shell sculpture, derived from both genetic and environmental factors,

is a recurrent problem experienced by authors dealing with studies on shallow marine assemblages (e.g.,

Hartmann 1982), which always include some phenotypically plastic species. Phenotypic plasticity, that

is the ability of an organism to express different phenotypes under different environmental conditions

(see, e.g., West-Eberhard 1989), may represent a fundamental resource for effective adaptation to coastal

environments, characterized by wide ranges and rapid changes of ecological parameters, and is a major

drawback for systematic investigations. Seemingly distinct features occurring in some infra-littoral

ostracod taxa lead taxonomists to propose a large number of specific names, which frequently have not

stood the test of time. In other cases, taxonomists “lumped” together very different forms (see, e.g., a

brief discussion on the genus Carinocy there is in Aiello & Szczechura 2001).

The genus Urocythereis

The genus Urocythereis was originally described by Ruggieri in 1950, with the intent to accommodate

three strictly related hemicytherid species, with subrectangular valves and an amphidont hinge provided

with a reniform posterior tooth in the right valve. These species were Cytherina favosa Roemer, 1838,

designated as type species, Cythereis margaritifera G.W. Muller, 1894 and Cythereis distinguenda

Neviani, 1928, from the Pliocene to Recent of the Mediterranean area. Since then, dozens of species

have been included in Urocythereis, especially from the Neogene to Recent of the Mediterranean area

and the eastern Atlantic. Aiello et al. (2004) assigned the south-western Atlantic species, previously

included in Urocythereis, to the new genus Ruggiericythere, due to the different structure of the

reticulation-ridges system. The allied genus Yezocythere Hanai & Ikeya, 1991 includes eastern Asian

European Journal of Taxonomy 193 : 1-35 ( 2016 )

species with a low subcentral tubercle, lacking in Urocythereis. Even though the authors recognized a

second distinctive feature, the smaller size of the median frontal scar, the value of this character at genus

level remained questionable. The Neogene to Recent Eastern African and Asian records of Urocythereis

(e.g., U. pohangensis Huh & Whatley, 1997; U. salebrosa Ahmad, Neale & Siddiqui, 1991), as well as its

presence in Paleogene deposits (e.g., U. bertelsae Kielbowicz, 1988), are, in our opinion, questionable.

In our present state of knowledge, Urocythereis is a Cenozoic genus possibly restricted to the infralittoral

and uppermost circalittoral zone (CM10 m, Athersuch 1977) of the Eastern Atlantic - Mediterranean area.

The taxonomy of this genus is complex due to the unusually wide variability of the shell ornamentation

and, consequently, species limits within the genus remain partly undefined.

A major contribution to the knowledge of the genus is the study by Athersuch (1977), who provided a

revision of all the then known living and some fossil species, in addition to an excellent iconography.

He described detailed ornamental patterns of five allied species (U. distinguenda (Neviani, 1928),

U. margaritifera, U. favosa (Roemer, 1838), plus U. neapolitana and U. britannica Athersuch, 1977,

described as new species) based on “nine arbitrary groups” of fossae. The author used these patterns to

demonstrate differences among groups of species, one being later described by Ruggieri & Russo (1980)

as a new genus, Nonurocythereis. These groups are not effective for discrimination at species level. The

outline of the muri, as well as the shape and dimension of the fossae, and their degree of anastomosis,

are rarely steady, so that reticulation varies “even between members of the same species” ( Athersuch

1977). Uncertainty is increased due to the frequent occurrence of celation (Sylvester-Bradley & Benson

1971), a morphological noise able to conceal, in some cases almost completely, ornamental patterns.

In a similar way, the relationship between normal pores and reticulation, used by authors for ostracod

morphology studies (e.g., Hunt & Yasuhara 2010), is blurred by various degrees of development of shell

calcification. Normal pores are well distinct in internal view, not in external view, and consequently the

relationship between pores and reticulum pattern is difficult to establish.

Reticulation

Shell reticulation represents a complex of features that, since the early contributions of Pokorny (1969a,

1969b), Liebau (1969, 1971) and Benson (1971, 1972), has been considered by ostracod workers

a fascinating object of study for taxonomy, evolution and related research fields. Ornament pattern

definition has been carried out especially on hemicytherid and trachyleberid taxa, frequently showing

a well-defined and more or less stable reticulation. Interspecific variations, in related species, are

sometimes limited to a few fossae and highly consistent in each species (Okada 1982b). The analysis of

the fossal pattern has been used for species discrimination (e.g., Al-Furaih 1977) and in studies on the

evolution and ontogeny of Trachybeleridoidea ( i.a ., Hunt 2007a, 2007b; Hunt & Yasuhara 2010; Tanaka

et al. 2011). Jones (1988) showed the possibility to extend the reticulation analysis to Paleozoic taxa.

Okada (1981, 1982a, 1982b) extensively studied the relationship of the epidermal cells to the reticulation

pattern and he recognized a direct correspondence between fossae and the underlying epidermal cells. Since

the muri represent the boundary of adjacent cells, the mesh arrangement reflects cell lineages, commonly

considered as genetically determined (i.a., Liebau 1971; Benson 1972; Irizuki 1993; Hunt 2007a).

Reticulated species frequently show a pattern of ridges where homologous fossae can be recognized

by their constancy in shape, number and arrangement and by the presence of landmarks such as pores,

ridges or spines (i.a. Benson 1972; Liebau 1991; Hunt 2007b; Hunt & Yasuhara 2010). In Urocythereis,

the number of fossae is relatively stable within species, while their shape and arrangement vary widely,

pores are frequently obscured by calcification and the features of anatomical landmarks, for example

muscle scars, can be difficult to define. Furthermore, alae, carinae or tubercles are not present in

Urocythereis. Consequently, an unambiguous identification of fossae and an accurate quantitative study

AIELLO G. et al., Shell variability of Urocythereis in the La Strea Bay (Italy)

of their variations (e.g., Hunt & Yasuhara 2010 on Poseidonamicus ) has proved unattainable. Ruiz et

al. (2006) hypothesized a direct influence of environmental factors on the variability of Urocythereis

reticulation.

Celation as a taxonomic issue

The development of an outer layer of calcite, the tegmen, overlapping the ornament of the valves, has

been named “celation” by Sylvester-Bradley & Benson (1971). The authors considered the tegmen as

a secondary thickening paving over the outer surface and thus obscuring, to some degrees, primary

reticulation. Benson (1972) hypothesized that the development of the tegmen represents the architectural

response to the requirement of a high shell strength. In deep and cold waters, this lightweight solution

may represent a case of parsimony in design balancing the scarcity of available skeletal material with

the development of high resistance to compression. Athersuch (1977) observed that the development

of celation (not recorded in juveniles) in Urocythereis distinguenda is related neither to depth nor to

other known ecological parameters, and suggested that the growth of the tegmen depends from the age

of the individuals: an intense celation would be typical of older adults. Another hypothesis considers

celation as a response to calcium saturated bottom waters, pertaining to the “environmentally cued

polymorphism” described by Peypouquet et al. (1980, 1981, 1988). Anyway, because celation varies

continuously, we agree with Neil (2000) on preferring the term “environmentally-cued variation”. In

this particular case the terms “celation” and “agradation” (“aggradation” in Neil 2000) are equivalent.

These two hypotheses are not mutually exclusive.

The ecological demands of an infralittoral genus can hardly be compared with the bathyal and abyssal

taxa studied by Benson (1972), who supposed that the secondary development of the top of the muri in

shallow water species, such as Cythere lutea O.F. Muller, 1785 and Hemicythere villosa (Sars, 1866),

has to be an adaptation to high energy sedimentary regimens. The attested preference of Urocythereis

for sandy bottoms (e.g., Athersuch et al. 1989; Aiello et al. 2006) and relatively agitated waters supports

this interpretation. It is understood that celation may be a consequence of simple genetic variation, or

a mixture of genetic and environmental effects. In any case, the occurrence of specimens with more

or less celated shells poses a taxonomic problem, whether we are dealing with two species (in this case

U. margaritifera and U. distinguenda ), with individuals of the same species that have possibly built their

valves in different physico-chemical conditions, or, alternatively, with younger and older adults of the

same species.

How many Urocythereis species occur in the La Strea Bay?

The assignment of the Urocythereis specimens of the La Strea Bay to the above mentioned three species

by Aiello & Barra (in Aiello et al. 2006) followed the original description and figures of G.W. Muller

(1894) and subsequent literature for U. margaritifera, and Athersuch (1977) for U. distinguenda.

Cythereis margaritifera was described by G.W. Muller in his monograph on the ostracods living in

the Gulf of Naples, and later recorded from Pliocene to Recent in the Mediterranean area. Cythereis

distinguenda is the name proposed by Neviani (1928) to replace the pre-occupied Cythere oblonga

Brady, 1866 (non C. oblonga M’Coy, 1844). Athersuch (1977) discussed nomenclatural problems

and designated a neotype for U. distinguenda from the shallow waters of Cyprus. This author figured

U. margaritifera specimens from Muller’s collection, showing individuals with rounded fossae as well

as with fossae reduced to punctae and foveolae (sensu Athersuch et al. 1989) because of celation. In

the same paper the specimens assigned to U. distinguenda show a marked celation with small-sized

irregular punctae-foveolae.

A third form present in the La Strea Bay bottom samples was left in open nomenclature and named

U. sp. 1 because of the resemblance with the specimens from the beach sands of Tripoli figured by

European Journal of Taxonomy 193 : 1-35 ( 2016 )

Table 1 . Coordinates, depth and granulometry of the studied samples. Abbreviations: VSF = Very Fine

Sands, FS = Fine Sands, MS = Medium Sands, CS = Coarse Sands.

Samples

Longitude E

Latitude N

Depth (m)

Grain size

17°53.67'

40°15.92'

0.43

17°53.76'

40°15.83'

1.30

MS-FS

17°53.57'

40°15.64'

3.21

CS-FS

17°53.64'

40°15.71'

2.43

CS-MS

17°53.73'

40°15.78'

2.40

17°53.87'

40°15.88'

1.40

17°53.93'

40°15.91'

0.90

CS-MS

17°53.52'

40°15.34'

4.40

17°53.6F

40°15.40'

4.78

17°53.72'

40°15.46'

4.50

CS-FS

17°53.83'

40°15.53'

3.40

17°53.92'

40°15.61'

2.58

CS-FS

17°54.02'

40°15.66'

1.73

17°54.10'

40°15.72'

17°53.85'

40°15.33'

1.52

MS-FS

17°54.0F

40°15.38'

2.30

CS-MS

17°54.17'

40°15.49'

1.51

CS-FS

17°54.32'

40°15.59'

1.11

CS-FS

17°54.0F

40°15.07'

1.42

MS-FS

17°54.25'

40°15.16'

1.50

CS-MS

17°54.26'

40°15.23'

1.49

17°54.45'

40°15.28'

1.30

MS-FS

17°54.28'

40°14.84'

0.50

CS-FS

17°54.34'

40°14.88'

0.94

MS-FS

17°54.45'

40°14.97'

1.12

17°54.60'

40°15.04'

1.50

MS-FS

17°54.47'

40°15.63'

0.20

MS-VFS

17°54.52'

40°14.67'

0.70

17°54.57'

40°14.71'

0.80

MS-VFS

17°54.66'

40°14.77'

0.65

MS-VFS

17°54.69'

40°14.6F

0.26

VFS

17°54.69'

40°14.51'

0.12

Barra (1997). This previously undescribed species has a marked affinity with U. exedata Uliczny,

1969, especially in the very distinct ocular riblet, a feature homologous to the prominent “ocular ridge”

described by Benson (1972) on some Bradleya species. The new species shows a distinct ornamental

pattern and specific features. Conversely, it seems very difficult to define an unambiguous boundary

between U. distinguenda and U. margaritifera, necessitating the examination of “intermediate” morphs,

in order to verily the existence of two separate species rather than a single highly variable species.

Material and methods

All the 32 samples were taken within the depth range of 0.12^1.78 m bsl (Aiello et al. 2006), from the

Recent bottom sediments of the La Strea Bay (Table 1). The samples contained 2133 valves and 128

carapaces, including both adults and young instars. All the specimens were studied and 150 shells were

AIELLO G. et al.. Shell variability of Urocythereis in the La Strea Bay (Italy)

selected for analyses and iconography. This study deals exclusively with adult specimens. Young instars

were considered only to evaluate the possible occurrence of celation in juveniles.

The analysis of the reticulation pattern and celation variations is based on scanning electron microscopy

(SEM) micrographs (carried out at Cisag, Universita di Napoli Lederico II). The above mentioned high

variability of the reticulation in Urocythereis species lead us to select some areas of the shell, where the

fossae-muri pattern was detectable with a minimum degree of uncertainty.

Fig. 2. Scheme of the five fossal groups used for reticulation pattern analysis. White arrow indicates the

pre-ocular bridge. A. Urocytheris margaritifera (G.W. Muller, 1894), ABMC 2014/057. B. Urocytheris

ilariae sp. nov., ABMC 2014/047.

European Journal of Taxonomy 193 : 1-35 ( 2016 )

Table 2. Catalogue number and sampling stations of the specimens used in the Morphomatica analysis.

Catalogue number

Samples

Catalogue numbers

Samples

ABMC 2014/125

ABMC 2014/142

ABMC 2014/126

ABMC 2014/143

ABMC 2014/127

ABMC 2014/144

ABMC 2014/128

ABMC 2014/145

ABMC 2014/129

ABMC 2014/146

ABMC 2014/130

ABMC 2014/147

ABMC 2014/131

ABMC 2014/148

ABMC 2014/132

ABMC 2014/149

ABMC 2014/133

ABMC 2014/150

ABMC 2014/134

ABMC 2014/151

ABMC 2014/135

ABMC 2014/152

ABMC 2014/136

ABMC 2014/153

ABMC 2014/137

ABMC 2014/154

ABMC 2014/138

ABMC 2014/155

ABMC 2014/139

ABMC 2014/156

ABMC 2014/140

The Morphomatica test was performed on drawings in transmitted light. They were carried out by means

of a Visopan Reichert, with a magnification of 201 times. The pictures were drawn with a technical pen

(thickness of the line: 0.30 mm) on tracing paper. The studied specimens are housed in the Aiello Barra

Micropaleontological Collection (ABMC), Distar, Universita degli Studi di Napoli Federico II.

Fig. 3. Detail of the antero-dorsal area in different morphs. — A-F. U. margaritifera (G.W. Muller,

1894). A. ABMC 2014/045. B. ABMC 2014/053. C. ABMC 2014/057. D. ABMC 2014/059. E. ABMC

2014/075. F. ABMC 2014/083. — G-H. U. ilariae sp. nov. G. ABMC 2014/038. H. ABMC 2014/047.

AIELLO G. et al. , Shell variability of Urocythereis in the La Strea Bay (Italy)

Reticulation pattern

In a highly variable genus such as Urocythereis the purpose of naming the position of all the meshes

seems difficult to achieve (in Urocythereis especially in the ventral area and in the posterior half of the

shell). Consequently, we identified five arbitrary fossal groups where the pattern can be recognized, both

in different species and specimens of the same species, as homologous without uncertainties (Lig. 2).

These groups were selected with the aim to define the structure of inter- and intra-specific reticulation

pattern variations. We chose muri/fossae sets that could be reliably considered homologous in

U. margaritifera and U. exedata. The two species are quite different and we hope that these groups may

be used for future comparisons among other species of Urocythereis.

Lossal groups are defined as follows:

a) Pre-ocular fossa (Pre-ocular bridge): presence of a preocular connection between the anterior marginal

rim and the ocular riblet, as figured in Pig. 2.

b) Anterodorsal group: a group of fossae located in the subocular area (B1, B2, B3, B4, Cl, C2, C3, C4)

as numbered in Pigs 2 and 3.

c) D3-D4-E9 group: these fossae form a triangular area situated in the anterocentral area, behind the

fourth concentric anterior ridge as figured in Pigs 2 and 4.

d) Dorsal median group: Athersuch (1977) defined this group as “two vertical rows of fossae directly

beneath the post-ocular sinus and directed towards the sub-central area” (al-a6, pi—(35 in Pigs 2 and 5);

e) Caudal group: the group of fossae (Cgl-Cg4) located on the caudal process area as figured in Figs 2

and 6.

i f

□4 E9

LLi

’si"

04 E9

LL!

■vT

h -

100 pm

Fig. 4. Detail of the antero-central area showing the fossal group D3-D4-E9 in different morphs. —

A-F. U. margaritifera (G.W. Muller, 1894). A. ABMC 2014/045. B. ABMC 2014/50. C. ABMC

2014/053. D. ABMC 2014/057. E. ABMC 2014/075. F. ABMC 2014/083. — G-H. U. ilariae sp. nov.

G. ABMC 2014/047. H. ABMC 2014/069.

Fig. 5. Dorsal median group in different morphs. — A-F. U. margaritifera (G.W. Muller, 1894).

A. ABMC 2014/037. B. ABMC 2014/04. C. ABMC 2014/053. D. ABMC 2014/057. E. ABMC 2014/075.

F. ABMC 2014/083. — G-H. U. ilariae sp. nov. G. ABMC 2014/047. H. ABMC 2014/069.

European Journal of Taxonomy 193 : 1-35 ( 2016 )

Fig. 6. Detail of the caudal group in different morphs. — A-F. U. margaritifera (G.W. Muller,

1894). A. ABMC 2014/045. B. ABMC 2014/053. C. ABMC 2014/059. D. ABMC 2014/062. E. ABMC

2014/075. F. ABMC 2014/083. — G-H. U. ilariae sp. nov. G. ABMC 2014/038. H. ABMC 2014/069.

Outline analysis

A quantitative analysis of ostracod morphology has been carried out by means of different methods,

including techniques of outline analysis (for a partial review, see Baltanas & Danielopol 2011). In recent

years, ostracod researchers seem leaning towards using the computer program Morphomatica, based on

a B-spline algorithm specifically adapted to ostracod valve outline (Baltanas et al. 2003; Linhart et al.

2006), which provides valuable results in specific discrimination ( i.a ., Iepure et al. 2007; Danielopol et

al. 2008; Ligios & Gliozzi 2012; Mazzini et al. 2014). The method has been described, for example, in

Gross et al. 2008. This technique has been used mostly on smooth or weakly ornamented ostracod taxa,

whereas we tested its effectiveness by using it to discriminate strongly reticulated forms. The material

consists of 20 left valves of the Urocythereis margaritifera-distinguenda group and 11 left valves of

U. ilariae sp. nov. (Table 2). On the basis of the shell features a clear discrimination between female and

male valves is not possible. The selection of the valves showing a higher h/1 ratio would be, in absence

of discontinuity, a mere example of circular reasoning. Consequently, we selected the best-preserved

valves, with no regard for their supposed sex, well-aware of the resulting limitations. Due to the presence

of unevenly preserved marginal denticulation we chose, unlike the usual procedure using transmitted

light microscope photographs, to analyse and digitize drawings generated using Visopan Reichert at

a magnification of x201. The results of Morphomatica were processed using Cluster analysis, non¬

metric multidimensional scaling (n-MDS) and analysis of similarities (One-way Anosim Pairwise Test)

by means of the program Primer 6 (Clarke & Gorley 2006).

Results

Celation, variability and specific assignment of Urocythereis sp. 1

The morphological variations in Urocythereis sp. 1 appear limited when compared with the

U. margaritifera-distinguenda group. Celation is rare and the fossae are never hidden by secondary

calcification; the structure of reticulation is somewhat constant. The basic pattern shows a close

resemblance to the Pliocene form described by Uliczny (1969) as Urocythereis favosa exedata and

elevated to the rank of species by Mostafawi & Matzke-Karasz (2006). Some stable shell features of

U. sp. 1 are different from those of the Pliocene taxon, leading us to describe a new species, named

U. ilariae sp. nov. as discussed in the systematic section.

Fossae shape and size variations and celation in the U. margaritifera-distinguenda group

Brady (1866) described a species from Recent sponge-sands of the Eastern Mediterranean as Cythere

oblonga , characterized by “somewhat distant, oblong, pittings”. The name C. oblonga was, however,

preoccupied by C. oblonga M’Coy, 1844; therefore, in 1928 Neviani assigned a new name, Cythereis

distinguenda , recognized by Athersuch (1977, 1982) as the “next available name for Brady’s species”.

AIELLO G. et al. , Shell variability of Urocythereis in the La Strea Bay (Italy)

In previous investigations, the present authors used the size of the fossae to discriminate between

U. margaritifera and U. distinguenda , being relatively large in the former species and very small in

the latter one. The finding of specimens exhibiting transitional features makes their specific attribution

difficult. The following morphs can be defined on the basis of the size and shape of the fossae:

Morph a (commonly assigned to U. margaritifera)'. medium-sized fossae, equidimensional, except in

the anterodorsal zone where they are medium- to small-sized; generally rounded, elongated or fused in

the anteroventral area (e.g., Tig. 16A, H);

Morph b (commonly assigned to U. margaritifera)'. medium-sized fossae rounded and equidimensional

on the whole surface of the shell (e.g., Tigs 2A; 16B);

Morph c (“transitional” form): mesh size from medium to very small, generally rounded (e.g., Tig. 17E);

Morph d (“transitional” form): fossae mainly elongated, from small to medium-sized (e.g., Tig. 17B);

Morph e (“transitional” form): the anterior area shows fossae very small or completely celated; the

remaining fossae are small and rounded (e.g.. Tig. 17D);

Morph f (commonly assigned to U. distinguenda)'. small-sized fossae; narrow and elongated in the

anterior part of the valve, rounded in the posterior part and mixed in the central area (e.g., Tig. 16D);

Morph g (commonly assigned to U. distinguenda)'. small-sized fossae, rounded or elongated in the

posterior half of the shell; very small (reduced into puncta) to completely celated in the anterior half

(Fig. 17C);

Morph h (commonly assigned to U. distinguenda)'. size of fossae ranging from small to very small;

elongated or rounded (Tig. 16G).

It has to be noted that in this latter group the muri are generally densely or sparsely papillate; in specimens

showing intense celation, papillae occur on the tegmen and are very sparse or lacking in correspondence

with the underlying muri, revealing the reticulation pattern (Tig. 7). A similar feature was observed by

Benson (1972) in the species Poseidonamicus nudus Benson, 1972.

In our opinion, these data suggest that U. margaritifera and U. distinguenda are morphotypes of the

same species.

Reticulation variability

The fossal groups show the following variations:

a. Pre-ocular fossa (pre-ocular bridge)

In U. margaritifera!distinguenda, a murus located in the antero-dorsal corner, in pre-ocular position,

generally connects the anterior marginal rim and the ocular riblet, which delimitate the marginal furrow

(Pigs 3A, C-E; 19D), forming a pre-ocular fossa. The pre-ocular bridge is more or less well defined in

U. margaritifera/distinguenda , including celated specimens, where it is highly developed and the pre¬

ocular fossa is reduced (Fig. 3B). In some specimens of U. margaritifera/distinguenda , the bridge is

absent and the furrow is continuous up to the eye tubercle (Pig. 3P).

The pre-ocular fossa never occurs in U. ilariae sp. nov. (Pig. 3G-H).

b. Anterodorsal group. Fossal pattern B1-B4 - C1-C4

In U. ilariae sp. nov., the presence of a murus between the fossae B5 and B4, connecting the second

and the third marginal riblets, is a stable feature and a possible landmark when comparing species

European Journal of Taxonomy 193 : 1-35 ( 2016 )

of Urocythereis. It is subdued in some very rare celated specimens (Fig. 18G). A composite fossa,

including the anastomized fossae Bl, B2, B3, B4, Cl and C2, shows slight intraspecific variability (Figs

2B; 3G-H); in some specimens (Fig. 18C, F) B4 and C4 are connected.

In U. margaritifera/distingiienda , B and C fossae never connect. The fossae B1 and B2 may be divided

(Fig. 17G), partially fused (Figs 2; 16B) or merged (Fig. 3E-F). Fossae B2-B3-B4 are never joined.

Cl and C2 are usually divided (Fig. 3C, F) and can show some degrees of anastomosis (Fig. 3D-E).

In some specimens celation may simulate mesh subdivision. For example, in Fig. 3B the C2 mesh is

almost completely closed by tegmen and small foveolae mirror the underlying fossa. Fossae C3 and C4

are never fused.

c. D3-D4-E9 group

In U. margaritifera/distingiienda , D4 and E9 are usually distinct (Fig. 4B-F), rarely joined together

(Fig. 4A). In a few specimens, D4 is partly divided, and D4 and E9 appear as an elongated subhorizontal

fossa (Fig. 4A). D3 is constantly distinct.

Fig. 7. Detail of papillae in heavily celated specimen of U. margaritifera (G.W. Muller, 1894), ABMC

2014/071.

AIELLO G. et al. , Shell variability of Urocythereis in the La Strea Bay (Italy)

In U. ilariae sp. nov., the fossae D3-D4-E9 form a steady triangular pattern with D4-E9 fused and D3 is

situated above them. In very rare celated specimens, D4 and E9 are distinct (Lig. 18G).

d. Dorsal median group. Fossal pattern al-a6, pi—p5

In U. margaritifera/distinguenda, an ideal scheme of this group can be represented as two rows: the

anterior row consists of six fossae, the posterior row includes five fossae, named al-a6 and p 1—p5

(Fig. 5A-F), respectively. This is seemingly in contrast with the scheme of Athersuch with 5+4 fossae;

in fact, the upper two fossae (al and (31), just below the post-ocular sinus, may be clearly observed

in dorsal view (Fig. 19D). In lateral view they appear very reduced or even completely hidden (Figs

5E-F; 16H; 17B). In the posterior row, between the 4th ((34) and 5th ((35) fossa, a small smooth area,

the “focus” of Athersuch (1977), is present. The lowermost fossae, herein named a6 and (35, pertain,

following Liebau’s scheme (1971), to the E-ring encircling the muscle-scar node.

We observed the following variations:

- fossa a3 divided in two subfossae (Fig. 16F);

- fossa a5 divided in two (Fig. 16F, H) or three (Fig. 17F) subfossae;

- fossa a6 divided in two (Figs 5F; 17G);

- fossa (33 partially connected with the centrodorsal fossae (Figs 16C; 17A).

The shape of the meshes shows a wide variability, partly due to celation, ranging from large rounded

fossae to small pits, including narrow foveolae (Fig. 5A-F).

In U. ilariae sp. nov., the dorsal median group shows a different pattern (Fig. 5G-H). In comparison

with the ideal scheme, the uppermost fossae (al, (31) are absorbed in the post-ocular sinus; a2 and (32

are located under the post-ocular sinus; a2 is alternatively isolated (Figs 5G; 19B) or fused with (32

(Fig. 18B). The fossa (32, in turn, is fused with a posterior fossa (Figs 5G; 19B). The a3-(33/a4-(34 meshes

may coalesce in part, generally forming a butterfly shaped quadruple fossa (Fig. 5G); in some specimens

a4 is fused with an anterior fossa (Fig. 5H).

e. Caudal group

In U. margaritifera/distinguenda , it consists of a basic pattern of three well-defined fossae, two marginal

and one internal with various shapes in different specimens (Fig. 6A-F). They may appear as a single

triple fossa (Fig. 17H) or as a single plus one double fossa (Fig. 2A). In the latter case, anastomosis

partially hides the identity of the fossae. Celation may completely obscure this pattern (Figs 6B; 17C).

In U. ilariae sp. nov., a fourth upper fossa (Cg4) merges with the caudal group, forming a multiple

L-shaped or elongated fossa; it can be more or less fused with another internal elongated multiple fossa

(Fig. 6G-H).

Our observations indicate that the reticulation pattern in the forms previously attributed to U. margaritifera

and U. distinguenda are identical. In U. ilariae sp. nov., well distinct patterns of homologous fossae can

be recognized.

Outline analysis

The valve outline of U. margaritifera (i.e., U. margaritifera “morph margaritifera!' plus U. margaritifera

“transitional morph”), U. distinguenda (i.e., U. margaritifera “morph distinguenda”) and U. ilariae sp.

nov. were analysed and compared. In Fig. 8A-C the “non normalized area” (size dependent) mode results

show that the variability of U. ilariae sp. nov. (Fig. 8A) is very limited. By contrast, in U. margaritifera

(Fig. 8B) the variability is relatively wide, linked to the length of the valves. Conversely, with the

“normalized area” (size independent) mode, a low variability is observed in U. margaritifera (Fig.

European Journal of Taxonomy 193 : 1-35 ( 2016 )

9B) while it is relatively high in U. ilariae sp. nov. (Fig. 9A). U. distinguenda shows an intermediate

variability in both modes (Figs 8C; 9C).

Comparisons of the mean outline of the three forms indicate that U. ilariae sp. nov. is positively separated

from U. margaritifera and U. distinguenda , while the discrimination of the latter forms is difficult. In

“normalized area” mode (Fig. 10B) U. ilariae sp. nov. shows a shorter length and a different shape in the

caudal and in the anterodorsal regions. Its shorter length is more evident in the mean outlines deriving

from “non normalized area” mode analysis (Fig. 10A).

Fig. 8. Comparison of valve outlines obtained by Morphomatica analysis. Results for “non-nonnalized

area” mode. A. U. ilariae sp. nov. B. U. margaritifera (G.W. Muller, 1894). C. U. distinguenda (Neviani,

1928).

Fig. 9. Comparison of valve outlines obtained by Morphomatica analysis. Results for “normalized area”

mode. A. U. ilariae sp. nov. B. U. margaritifera (G.W. Muller, 1894). C. U. distinguenda (Neviani,

1928).

Fig. 10. Comparison of mean outlines of U. ilariae sp. nov. (green), U. margaritifera (G.W. Muller,

1894) (light blue) and U. distinguenda (Neviani, 1928) (dark blue) obtained by the Morphomatica

analysis. A. Results for “non-normalized area” mode. B. Results for “normalized area” mode.

AIELLO G. et al., Shell variability of Urocythereis in the La Strea Bay (Italy)

(Nr^ocrtof^^t^tcor^omuDoproJDocritNkDoofMroLorricrvLnin

*frm<Y>roir><t<TinrocNroin«t*Tinm<t*tincNicNfo^«5frmr\i<YifN

rHrHrHrH^rHtHrHrHrHtHrHr-lrH <rH r-4 r-4 t-H r-H tH rH rH rH rH rH rH rH rH

on on

species

y U. margaritifera

U. distinguenda

■ U. ilariae

A2a

A2b

species

y U. margaritifera

U. distinguenda

■ U. ilariae

Fig. 11. Cluster analysis perfonned on valve outlines obtained by Morphomatica analysis. A. Dendrogram

for “non-nonnalized area” mode. B. Dendrogram for “normalized area” mode.

European Journal of Taxonomy 193 : 1-35 ( 2016 )

Cluster analysis for “normalized area” mode reveals two main clusters, the first (Al) includes three valves

of U. ilariae sp. nov., the second (A2) consists of all the remaining specimens (Fig. 11B). This second

cluster is subdivided into two subclusters: A2a, including nine valves pertaining to U. distinguenda and

three specimens of U. margaritifera and A2b, where all the three forms are present (eight U. ilariae

sp. nov., two U. distinguenda and six U. margaritifera valves).

The “non normalized area” mode analysis (Fig. 11 A) discriminates two main clusters: Bl, consisting of

three valves of U. margaritifera and four of U. distinguenda , and B2 including the remaining specimens.

The Anosim Pairwise Test applied both to the “non normalized area” (Fig. 12A) and “normalized area”

mode (Fig. 12B) displays that U. ilariae sp. nov. and U. distinguenda are separated on the basis of the

outline analysis (R = 0.603; R = 0.628). Conversely, U. margaritifera cannot be discriminated from

U. ilariae sp. nov. or from U. distinguenda.

N-Mds analysis provided comparable results (Fig. 13). The distribution areas of U. ilariae sp. nov. and

U. distinguenda are well defined for both “non normalized area” mode (Fig. 13A) and “normalized

area” mode (Fig. 13B), whereas the distribution of U. margaritifera specimens overlaps both U. ilariae

sp. nov. and U. distinguenda.

U. ilariae vs U. margaritifera

0.263

0.006

U. ilariae vs U. distinguenda

0.603

0.001

U. margaritifera vs U. distinguenda

0.070

0.165

U. ilariae vs U. margaritifera

0.104

0.078

U. ilariae vs U. distinguenda

0.628

0.001

U. margaritifera vs U. distinguenda

0.279

0.008

Fig. 12. Analysis of similarities (One-way Anosim Pairwise Test). A. R statistic and p value for “non-

normalized area” mode. B. R statistic and p value for “normalized area” mode.

AIELLO G. et al ., Shell variability of Urocythereis in the La Strea Bay (Italy)

species

▼ U. margaritifera

U. distinguenda

U. ilariae

species

y U, margaritifera

U. distinguenda

■ U. ilariae

Fig. 13. Non-metric multid im ensional scaling (n-MDS) analysis. A. Results for “non-normalized area”

mode. B. Results for “normalized area” mode.

European Journal of Taxonomy 193 : 1-35 ( 2016 )

Taxonomy

Classification follows Liebau (2005) and, for the attribution to subfamily, Hartmann & Puri (1974).

Subclass Ostracoda Latreille, 1802

Superorder Podocopomorpha Kozur, 1972

Order Podocopida Sars, 1866

Suborder Cytherocopina Griindel, 1967

Infraorder Nomocytherinina Liebau, 1991

Superfamily Trachyleberidoidea Sylvester-Bradley, 1948

Family Hemicytheridae Puri, 1953

Subfamily Urocythereidinae Hartmann & Puri, 1974

Genus Urocyth ereis Ruggieri, 1950

Urocythereis ilariae sp. nov.

um:lsid:zoobank.org:act:607A810F-773C-4F8F-91E7-D2EB5223CB7D

Figs 2B; 3G-H; 4G-H; 5G-H; 6G-H; 14; 18A-J; 19A-C, E-J

Urocythereis favosa (Roemer) n. ssp. Bassiouni, 1965: pi. 40, figs 8-9.

Urocythereis favosa (Roemer) subsp. - Wouters 1973: 385, pi. 2, fig. 7.

Urocythereis sp. -Bonaduce, Ciampo & Masoli 1976: 46, pi. 22, fig. 9.

? Urocythereis sp. - Athersuch 1977: pi. 17, fig. 2.

Urocythereis aff. U. favosa (Roemer) -Arbulla, Pugliese & Russo 2001: fig. 3t.

? Urocythereis sp.l - Barra 1997: 82, pi. 4, fig. 6.

Urocythereis sp.l - Aiello et al. 2006: tables 3, 10. —Aiello, Barra & Parisi 2013: fig. Id.

Diagnosis

A large reticulate species of Urocythereis , subrectangular in lateral view, inflated-ovate in dorsal view.

Reticulum with large polygonal-rounded, frequently coalescing, large fossae separated by broad muri.

In the anteroventral area the muri form distinct riblets running parallel to the margin.

Etymology

In honour of our friend and collegue Ilaria Mazzini, in recognition of her important contribution to

ostracodology.

Type material (4 carapaces, 43 valves: 29 adults and 14 juveniles)

Holotype

IONIAN SEA: ABMC 2014/03

Paratypes

IONIAN SEA: ABMC2 014/026-036, ABMC 2014/038, ABMC 2014/042, ABMC 2014/044, ABMC

2014/046-049, ABMC 2014/063-064, ABMC 2014/069, ABMC 2014/072-073, ABMC 2014/080,

ABMC 2014/097-103, ABMC 2014/120-135.

Stratum typicum

Recent.

AIELLO G. et al. , Shell variability of Urocythereis in the La Strea Bay (Italy)

Locus typicus

La Strea Bay (Porto Cesareo Lagoon), Southern Italy, Ionian Sea, sampling station E4, 17°54'25" N,

40°15'59" E, depth 1.5 m bsl.

Description

Measurements (holotype): LV: L = 0.85 mm, H = 0.44 mm (Pig. 18A).

Large (L = 0.85-0.90 mm) species of Urocythereis , characterized by large fossae and strongly developed

muri, subrectangular in lateral view, inflated-ovate in dorsal view. Valves strongly calcified and thick.

Dorsal margin gently, unevenly convex, ventral margin weakly sinuous; anterior end broadly rounded,

denticulate in the lower part; upper part of the posterior margin concave, lower part of the posterior margin

convex, variably denticulate, forming short blunt caudal process located below mid-height. Maximum

height at anterior cardinal angle, greatest length below mid-height. Surface of valves coarsely reticulate.

Lossae, showing subrounded or irregular shape, coalesce, especially in marginal areas, forming both

multiple anastomized elongated fossae and deep sulci parallel to margin. The corresponding muri tend

to form a system of concentric riblets. Marginal rim starts from anterior part of dorsal margin, behind

eye tubercle (Pig. 19C), and ends in posteroventral angle. Second riblet, constantly well developed,

runs parallel to margin of valve except posterior end. This ocular riblet is connected with eye tubercle

and rises above dorsal margin. Marginal rim and second riblet not connected. Third riblet, irregularly

developed, delimits anteriorly the reticulum stricto sensu from subocular area to posterior part of ventral

area and is connected with second riblet anteriorly, at mid height, through single radial mums; in the

ventral area second and third riblets converge and, in lateral view, they seem apparently to be connected,

but ventral view (Pig. 19A) shows they remain separate. The fossae between second and third riblet

mainly anastomized. Pourth riblet fully part of reticulum, and shows a rather regular parallel trend only

in anterocentral area. Surface of central area irregularly reticulate with subrounded/polygonal fossae

with a low degree of anastomosis. Conversely, fossae located in proximity of caudal process coalesce

following a longitudinal trend. Rare specimens show celation, never fully developed. Muri smooth, not

papillate (Pig. 19E).

Hinge holamphidont (sensu Scott 1961): in left valve posterior hinge socket elongate and curved;

anterior element formed by ovate-rounded (or elongate) tooth and elongate socket; median bar smooth;

its posterior thickening forms, in some cases, barely defined toothlet; right valve hinge complementary,

with faintly crenulate teeth (Pigs 181—J; 19G-J).

Inner lamella, marginal pore canals and muscle scar pattern (Pig. 19F) characteristic of genus (details

inAthersuch 1977).

Distribution

The species occurs in the Recent of the Mediterranean: Gulf of Naples (Bassiouni 1965), Sardinia

(Arbulla et al. 2001), South Adriatic Sea (Bonaduce et al. 1976) and possibly Libya (see section

Remarks); it has previously been recorded in fossil associations from the Tyrrhenian (upper Pleistocene)

of Tunisia only (Wouters 1973). Distribution data are summarized in Fig. 14.

Remarks

U. ilariae sp. nov. has previously been assigned to U. favosa (Bassiouni 1965; Wouters 1973), type

species of the genus Urocythereis (neotype figured by Athersuch 1977). The reticulation of U. favosa

differs from that of U. ilariae sp. nov. in the different style of fossal anastomosis. This is mostly evident,

for example, in the anterodorsal zone, where the continuous depressed area formed by the fossal pattern

C1-C2/B1-B4 is present in U. ilariae sp. nov. and absent in the Pliocene species.

European Journal of Taxonomy 193 : 1-35 ( 2016 )

The shell characters of U. exedata , described by Uliczny (1969) as a subspecies of U. favosa (SEM

micrographs in Mostafawi & Matzlce-Karasz 2006), show a close resemblance to those of U. ilariae sp.

nov., especially in the structure of the ocular riblet, homologous to Bradley a J “ocular ridge” (Benson

1972). The Pliocene species probably represents an ancestor of the living form. The two species differ

in some reticulum features. In the anteroventral area of U. ilariae sp. nov. the third and the fourth riblets

are connected ventrally and anteriorly; consequently they delimit the merged C fossae, forming an

anteroventral furrow enclosed by muri. Conversely, in U. exedata the anteroventral area is characterized

Fig. 14. Distribution of U. ilariae sp. nov. and U. margaritifera (G.W. Muller, 1894). Circles = Recent;

triangles = Pleistocene; squares = Pliocene; filled = certain; empty = uncertain.

AIELLO G. et al, Shell variability of Urocythereis in the La Strea Bay (Italy)

by a segment of the third riblet encircled by an elongated ring made up of B and C anastomized fossae,

anteriorly and ventrally connected. In the anterodorsal area of U. ilariae sp. nov., the third concentric

riblet is more or less developed in different specimens (Ligs 2B; 18D, L), while in U. exedata in the

anterodorsal area the fossae of the B group coalesce with C and D fossae, the muri follow a radial trend

and consequently the third concentric riblet is virtually absent.

The assignment of the North-African form, figured by Athersuch (1977) as Urocythereis sp. and by Barra

(1997) as Urocythereis sp. 1, to U. ilariae sp. nov. needs further investigation. At the current state of

knowledge we are inclined to interpret the morphological differences between the central Mediterranean

species and the Lybian deme as the beginning of an allopatric speciation.

Urocythereis margaritifera (G.W. Muller, 1894)

Ligs 2A; 3A-L; 4A-L; 5A-L; 6A-L; 16A-K; 17A-J; 19D

Cythere oblonga Brady, 1866: 353, pi. 59, figs 5a-d ( non C. oblonga M’Coy, 1844).

Cythereis margaritifera G.W. Muller, 1894: 368, pi. 32, figs 26, 29, 32, 35-37.

Cythereis (. Auris) distingue nda Neviani, 1928: 105 (synonymy only) (non p. 105 description and pi. 2,

figs 91-93).

Urocythereis margaritifera alba Uliczny, 1969: 65, pi. 15, fig. 9.

Urocythereis sp. Athersuch, 1977: pi. 17, fig. 5.

Urocythereis sp. 2 Barra, 1997: 82-83, pi. 4, fig.8.

Urocythereis sp. 3 Barra, 1997: 83, pi. 4, fig. 11.

Hemicythere (Urocythereis) margaritifera - Ruggieri 1953: 94, pi. 6, fig. 1.

Urocythereis britannica Athersuch - Kubanc 1995: 32-33, pi. 8, figs 4a-b.

Urocythereis crenulosa (Terquem) - Mostafawi & Matzke-Karasz 2006: pi. 6, fig. 9 (non pi. 8, fig. 1;

non Cythere crenulosa Terquem, 1878).

Urocythereis distinguenda - Athersuch 1977: 257, 259, pi. 7, figs 1-6; pi. 8, figs 1-6; pi. 9, figs 1-5;

pi. 12, figs 5-6; figs 3c-d. —Athersuch 1979: fig. 2.19. —Aiello et al. 2006: tabs. 3, 7, 10. —Aiello,

Barra & Parisi 2013: fig. lb.

Urocythereis favosa (Roemer) -Barbeito-Gonzalez 1971: 279, pi. 13, figs lb, 3b, 4b, 6b, pi. 46, figs 24-

27 (non pi. 13, figs 2b, 5b, pi. 46, figs 28-29). — Doruk 1974: pi. 38, fig. 3, pi. 40, figs 1-3 (non pi. 34,

figs 1-2, pi. 38, figs 1-2). —Puri 1974: pi. 13, fig. 3. —Tunoglu 1999: pi. 7, fig. 1.

Urocythereis aff. U. favosa - Bonaduce, Ciampo & Masoli 1976: 45, pi. 22, fig. 8 (sic fig. 7).

? Urocythereis favosa - Triantaphyllou, Tsourou, Koukousioura & Dermitzakis 2005: pi. 3, fig 11.

Urocythereis margaritifera - Athersuch 1977: 260, 262, pi. 12, figs 1-4; pi. 13, figs 1-6; pi. 14, figs

1-5; figs 3e-f. —Tsapralis 1981: 100, pi. 1, fig. 1. —Lachenal 1989: 175-176, pi. 3, fig. 14. —Kuban 9

1995: 31-32, pi. 8, figs 3a-c. —Aiello et al. 2006: tabs. 3, 5. — Per 9 in-Pa 9 al & Balkis 2012: pi. 2,

fig. 3. —Aiello, Barra & Parisi 2013: fig. la.

? Urocythereis margaritifera - Aranki 1987: 72, pi. 19, figs 5-7. — Stancheva 1989: pi. 2, fig. 9. —

§afak, Av§ar & Meri 9 1999: pi. 3, fig. 12.

Urocythereis cf U. margaritifera - Arbulla, Pugliese & Russo 2001: fig. 3s.

Urocythereis ? margaritifera - Aiello, Barra & Parisi 2013: fig. lc.

Urocythereis margaritifera alba - Breman 1976: 63-64, pi. 9, fig. 124. —Aiello, Barra, De Pippo &

Donadio 2012: pi. 2, fig. 8.

? Urocythereis margaritifera alba - Uffenorde 1972: 79, pi. 8, fig. 9.

Urocythereis margaritifera margaritifera - Uliczny 1969: 65, pi. 15, fig. 8.

? Urocythereis margaritifera margaritifera - Sissingh 1972: 128, pi. 10, fig. 8.

Urocythereis seminulum (Seguenza) - §afak, Av§ar & Meri 9 1999: pi. 3, fig. 11.

Urocythereis sp. - Mostafawi, 1994: 107, pi. 7, fig. 6.

European Journal of Taxonomy 193: 1-35 (2016)

Distribution

The species is widely distributed in the infralittoral waters of the Eastern Mediterranean (Brady 1866;

Barbeito-Gonzalez 1971; Doruk 1974; Athersuch 1977, 1979; Kubang 1995; Tunoglu 1999; Pergin-

Pagal & Ballcis 2012), the Tyrrhenian Sea (G.W. Muller 1894; Puri 1974) and the southern Mediterranean

(Athersuch 1977; Lachenal 1989; Barra 1997). Recordings from the Black Sea are uncertain: the

specimen figured by Stancheva (1989) is a young instar, and Schornikov (1969) reported Muller’s

original drawings. The species is present in the southern part of the Adriatic Sea; the findings in the

central and northern Adriatic are doubtful (Uffenorde 1972; Bonaduce et al. 1976; Breman 1976).

Fossil specimens have been reported from the Upper Pleistocene-Holocene of the Gulf of Gabes

(Lachenal 1989), the Pleistocene of Southern Italy (Ruggieri 1953; Aiello et al. 2012), Zakynthos

(Tsapralis 1981), the Northern Peloponnesus (Mostafawi 1994) and, possibly, Rhodes (Sissingh 1972)

and from the Pliocene of Cephalonia (Uliczny 1969). Distribution data are su mm arized in Fig. 14.

The presence of the species in Miocene sediments ($afak et al. 1999) has to be confirmed by further

studies.

Remarks

The analysis of the shell features of the Urocythereis population in the La Strea Bay and comparisons

with the literature have convinced us that U. margaritifera and U. distinguenda (= U. oblonga ) are two

morphotypes of the same species. In particular, we consider the latter “species” as the celated variation

of the former. Celation is not expressed homogeneously on the valves in all the specimens; consequently,

also “transitional” shells show different morphs.

The original illustration by Muller (1894: pi. 32, fig. 26) shows anteroventral fossae horizontally merged;

the lectotype reported by Athersuch (1977: pi. 13, fig. 2) and the Libyan specimen figured by Barra

(1997, as U. sp. 2) shows the same feature. Presently, we do not regard this character as diagnostic, due

to the observed variability.

Fig. 15. Scheme of the hidden reticulation evidenced in a celated specimen, LV, sample E6, ABCM

2014/053. Same specimen as Fig. 16G.

AIELLO G. et al. , Shell variability of Urocythereis in the La Strea Bay (Italy)

Athersuch (1977) figured some appendages, including the right copulatory appendage, of U. distinguenda

and the left copulatory appendage of U. margaritifera. Regarding the discrimination of the two species,

the author stated that in U. margaritifera the ductus ejaculatorius is short and is contained within the

area of the appendage, whereas in U. distinguenda the duct is much longer and passes beyond the ventral

margin. Examination of Athersuch’s illustrations (figs 4.d; 5.i) and a comparison with Muller’s drawing

of the male copulatory appendage of Cythereis margaritifera (pi. 32, fig. 32) show that only very subtle

differences are present and they represent, in our opinion, intraspecific variations.

The maximum mesh size is reached in the subspecies Urocythereis margaritifera alba Uliczny, 1969.

This form, in which celation is not developed, does not occur in the La Strea Bay. In some specimens

the SEM micrographs revealed a feeble trace of the muri underlying the secondary calcification, as

shown in Tig. 15. The comparison of this hidden reticulation with the specimens figured by Uliczny

(1969), Breman (1976) and Aiello et al. (2012) suggests that U. m. alba is a non-celate morphotype of

U. margaritifera. The North Adriatic form figured by Uffenorde (1972) (very similar to the Pliocene

specimen figured by §afak et al. 1999 as U. margaritifera) shows some tiny differences in the reticulation

pattern and the assignment to U. margaritifera is queried.

The Libyan form figured by Athersuch (1977: pi. 17, fig. 5) as U. sp. and by Barra (1997) as U. sp. 3 fits

the U. margaritifera morph c (Pig. 17E) well.

The left valve, figured by Aranki (1987) from the western Mediterranean shallow waters, shows some

minor differences in the reniform outline and in some details of the reticulum. The relationships between

Mediterranean and Atlantic forms (i.e., between U. margaritifera and U. britannica , frequently reported

as U. oblonga) need further investigations.

Ruggieri (1953) hypothesized that U. favosa and U. margaritifera might be conspecific, the latter species

representing a subspecies of the former. In spite of the similarity of the two forms, some features of the

reticulum seem to allow a separation of the two species. In U. favosa (neotype figured in Athersuch

1977) the fossae B3 and B4 are merged, as well as C3 and C4; in U. margaritifera they are distinct; in

U. favosa the fossae D2-D1 and a4 coalesce while in U. margaritifera they are distinct. In the caudal

group the fossa Cg4 in U. margaritifera is separate, whereas in U. favosa the arrangement of the fossae is

similar to that in U. ilariae sp. nov. In the La Strea Bay, and possibly in the Recent of the Mediterranean,

U. favosa s.s. is not recorded and we prefer to retain them as separate species.

Some Urocythereis spp. from the Pliocene of Rhodes have been described by Terquem (1878) and figured

by Mostafawi (1989). They are distinct from U. margaritifera in some characters of the reticulum. By

contrast, the specimen from Cephalonia figured by Mostafawi & Matzke-Karasz (2006) as U. crenulosa

fits well with some specimens of U. margaritifera from Porto Cesareo.

The Atlantic forms reported as U. britannica and (erroneously) as U. oblonga (e.g., Guillaume et

al. 1985; Ruiz et al. 2006) show a high variability and a complex affinity with U. margaritifera and

U. favosa and they have not been considered in the present study.

Discussion

The comparison of five selected fossae-muri homologous groups convinced us that at present two

species of Urocythereis live in the Porto Cesareo Lagoon and not three as previously reported by Aiello

et al. (2006, 2013). Reticulum analysis demonstrates that the ornamentation patterns of U. margaritifera

and U. distinguenda (sensu Aiello et al. 2006) are basically identical, and that the differences between

morphs are similar, for example, to the continuous (non-polymorphic s.s.) variations described by Neil

(2000) for the hemicytherid species Chapmanella flexicostata (Chapman, 1914).

European Journal of Taxonomy 193: 1-35 (2016)

Fig. 16. U. margaritifera (G.W. Muller, 1894). A. LV, sample E4, ABCM 2014/037. B. RV, sample E4,

ABCM 2014/040. C. LV, sample A2, ABCM 2014/083. D. RV, sample E4, ABCM 2014/039. E. LV,

sample D3, ABMC 2014/075. F. RV, sample E4, ABCM 2014/041. G. LV, sample E6, ABCM 2014/053.

H. RV, sample H, ABCM 2014/065.1. LV (A-l instar), sample E6, ABCM 2014/054. J. LV (A-2 instar),

sample D3, ABCM 2014/114. K. RV(A-1 instar), sample A2, ABCM 2014/056.

AIELLO G. et al ., Shell variability of Urocythereis in the La Strea Bay (Italy)

Fig. 17. U. margaritifera (G.W. Muller, 1894). A. LV, sample E6, ABCM 2014/045. B. LV, sample B3,

ABCM 2014/059. C. LV, sample E6, ABCM 2014/050. D. LV, sample B3, ABCM 2014/062. E. LV,

sample A2, ABCM 2014/055. F. LV, sample H, ABCM 2014/070. G. LV, sample B2, ABCM 2014/058.

H. RV, sample H, ABCM 2014/066. 1. LV, sample H, ABMC 2014/071. J. RV, internal view, sample E6,

ABMC 2014/052.

European Journal of Taxonomy 193: 1-35 (2016)

Fig. 18. U. ilariae sp. nov. A. Holotype, LV, sample E4, ABMC 2014/038. B. Paratype, RV, sample

E4, ABMC 2014/044. C. Paratype, LV, sample E6, ABMC 2014/028. D. Paratype, RV, sample E4,

ABMC 2014/036. E. Paratype, LV, sample H, ABMC 2014/069. F. Paratype, RV, sample E5, ABMC

2014/030. G. Paratype, LV, sample E5, ABMC 2014/032. H. Paratype, RV, (A-l instar), sample D3,

ABMC 2014/121. 1. Paratype, RV, internal view, sample E4, ABMC 2014/033. J. Paratype, LV, internal

view, sample E4, ABMC 2014/034.

AIELLO G. et al ., Shell variability of Urocythereis in the La Strea Bay (Italy)

Fig. 19. — A-C, E-J U. ilariae sp. nov. A. Paratype, C in ventral view, sample G2, ABCM 2014/26.

B. Paratype, C in dorsal view, sample D3, ABCM 2014/80. C. Paratype, C in dorsal view, sample F3,

ABCM 2014/27. E. Paratype, LV, sample E6, ABMC 2014/028. F. Paratype, LV, detail of muscle scars,

sample E4, ABMC 2014/034. G. Paratype, RV, detail of the anterior part of the hinge, sample E4,

ABMC 2014/033. H. Paratype, LV, detail of the posterior part of the hinge, sample E4, ABMC 2014/034.

I. Paratype, RV, detail of the posterior part of the hinge, sample E4, ABMC 2014/033. J. Paratype, LV,

detail of the anterior part of the hinge, sample E4, ABMC 2014/034. — D. U. margaritifera (G.W.

Muller, 1894), C in dorsal view, sample Cl, ABCM 2014/060.

European Journal of Taxonomy 193 : 1-35 ( 2016 )

Our observations confirm only partly Athersuch’s statement that celation is present exclusively in adult

individuals of Urocythereis . Actually, we have recorded a few penultimate instars showing a certain

degree of celation (Fig. 161, K). In young A-2 instars, celation is not recorded or is very poorly developed

(Fig. 16J).

The results of the morphometric analysis by means of the Morphomatica program need further

interpretation.

The Anosim Pairwise Test and n-MDS analysis confirm that the outlines of U. margaritifera and

U. distinguenda cannot be discriminated, as showed by the reticulum analysis, supporting the idea that

they are different morphs of the same species. Furthermore, the Anosim Pairwise Test and n-MDS analysis

display a clear separation between U. ilariae sp. nov. and U. margaritifera “morph distinguenda ”, while

they are not able to discriminate between U. ilariae sp. nov. and U. margaritifera “morph margaritifera ”,

in spite of the evidence that they show different specific reticulation features, due to the wide outline

variability of the latter form.

By contrast, the comparison of the mean outlines derived from the “non normalized area” mode allows

the discrimination between U. ilariae sp. nov. and U. margaritifera sd.

We interpret the peculiar distribution of U. ilariae sp. nov. and celated U. margaritifera (“morph

distinguenda”) in two different ways. The first is to separate them, due to the obvious attribution to a

different species showing a relatively low variability in outline and reticulation. On the other hand, the

distribution of U. margaritifera “morph distinguenda ” needs a different explanation. We suggest that

the outlines of celated specimens show a certain degree of separation due to the secondary calcification

of the valves. According to the Van Morkh oven’s investigations (1962), in specimens of Cypris pubera

a rich calcium diet induced secondary thickening of the shell. The morphological alterations developed

to such a point that, in the author’s words, “most likely they would have been classified as a distinct

species, if the history of the individuals had not been known”.

In some Urocythereis species, the age effect could somewhat replace the food-related secondary

calcification observed by Van Morkhoven.

Our favourite solution to the “V. margaritifera - U. distinguenda problem” is to consider the distinguenda

morph as the result of a supposed gerontic process, possibly in waters supersaturated with CaC0 3

(see Peypouquet et al. 1988, and references therein), which caused both celation and a slight outline

modification, partly recognized by Morphomatica.

The presence of celation in juveniles seems to contradict this interpretation, nonetheless it has been

considered that the presence of long A-2 and A-l stages duration has been recorded, as for example by

Hagerman (1969) in Hirschmannia viridis (O.F. Muller, 1785). We suggest that overwintering juveniles

(Horne 1983 and references therein) could in some cases develop the same gerontic features as the

adults.

Conclusions and additional remarks

In the present investigation we attempted to examine the variability of the Urocythereis shell characters of

the species occurring in the Ta Strea Bay. Our results show that we deal here with two species: U. ilariae

sp. nov., displaying a low variability and a low degree of celation, and U. margaritifera , a species with

a high (continuous, non polymorphic) variability and able to express intense celation. The specific name

U. distinguenda has previously been assigned, in our opinion, to celated specimens of U. margaritifera

(“agrading” morph, sensu Peypouquet et al. 1988), and it is not even a valid subspecies. Furthermore,

we have considered U. margaritifera alba as a “fully non-celated” (“degrading” sensu Peypouquet et

AIELLO G. et al, Shell variability of Urocythereis in the La Strea Bay (Italy)

al. 1988) morph of U. margaritifera. In the La Strea Bay this form is absent, probably due to the

persisting supersaturation of calcium carbonate, as demonstrated by the high percentage of miliolids in

taphocoenoses of the bay, ranging from 12.16% to 35.08% (Aiello et al. 2006). Actually, miliolids are

benthic foraminifera preferring waters rich in calcium carbonate (e.g., Jorissen 1988) and very rare in

low pH environments (e.g., Aiello et al. 2012 and references therein). In such a calcium super-saturated

environment, all the adult specimens, and rare penultimate instars, show at least a moderate celation.

Since the La Strea Bay is populated by a subtropical biocoenosis, our observations are in agreement with

the statement of Peypouquet et al. (1988), who pointed out the relationship between aggradation and

high water temperature.

In U. ilariae sp. nov., the less developed celation highlights different behaviour in Urocythereis species.

Consequently, we suggest that three main factors influence the tegmen development: a genetically

determined (specific) ability to express celation, the saturation in CaCCf of the bottom waters and

the age of the organism (adult or penultimate instar). Urocythereis margaritifera , V m. alba and U.

distinguenda are morphotypes derived by environmentally cued variability.

The definition of the variability in a single population may provide, in our opinion, a step toward a

broader understanding of the variability within Urocythereis through time and space.

Morphological variations of shallowmarine ostracod species living in different areas (e.g., Ishizaki 1975;

Hartmann 1982) may be interpreted as the beginning of an allopatric speciation, and future investigations

of the U. margaritifera/U. britannica group could discriminate these species or, conversely, demonstrate

that they are subspecies or morphotypes. A more complex problem is the definition of the relationship

of the Miocene Atlantic Urocythereis pertaining to the U. favosa group (e.g., U. favosa in Nascimento

1988) that possibly recolonized the Mediterranean at the end of the Salinity Crisis with the Pliocene-

Recent forms. An estimation of the total number of Urocythereis species in the Mediterranean Neogene

and their phylogenetic relationships represent open questions.

Acknowledgment

The authors thank Alexander Liebau for some useful suggestions in the very beginning of this

investigation, Dave Horne and an anonymous reviewer for their helpful co mm ents and Roberto de’

Gennaro (Cisag, Universita di Napoli Lederico II) who took the SEM micrographs.

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Manuscript received: 13 October 2015

Manuscript accepted: 14 December 2015

Published on: 3 May 2016

Topic editor: Rudy Jocque

Desk editor: Kristiaan Hoedemakers

Printed versions of all papers are also deposited in the libraries of the institutes that are members of the

EJT consortium: Museum national d’Histoire naturelle, Paris, France; Botanic Garden Meise, Belgium;

Royal Museum for Central Africa, Tervuren, Belgium; Natural History Museum, London, United

Kingdom; Royal Belgian Institute of Natural Sciences, Brussels, Belgium; Natural History Museum of

Denmark, Copenhagen, De nm ark