Regular Echinoids Research Articles

Selected regular echinoids (Echinoidea) from the upper Campanian–Maastrichtian along the western borders of the Northern Oman Mountains, with description of a new species

Thirteen species of regular echinoid, in ten genera, are recorded from the upper Campanian–Maastrichtian Qahlah and Simsima formations of two sections located along the western borders of the Northern Oman Mountains. Twelve of these are from the Simsima Formation in the Jebel El Rawdah section, four from the Qahlah and Simsima formations in the Jebel Huwayyah section. One new species, Hattopsis muradi, is described from the Jebel El Rawdah section. The status of the genus Pseudorthopsis is confirmed; differences between it and Orthopsis are discussed and Orthopsis sanfilippoi is transferred to Pseudorthopsis, here being recorded for the first time from the Arabian Gulf region. Revision of three species referred to Hattopsis and nine species ascribed to Protechinus (= Noetlingia, Noetlingaster) has elucidated the relationship between these two genera and affirmed the distinctiveness of Hattopsis. Hattopsis sphericus and Echinotiara perebaskinei are recorded for the first time from Jebel Huwayyah. All species identified are compared with other related taxa, and their stratigraphical ranges, affinities, palaeobiogeography and palaeoecology discussed.

Using the Discontinuous Bi-viscosity model to analyze the three-dimensional flow field and local scour behavior around the Claviaster libycus

Abstract Previous studies have suggested that irregular echinoids exhibit higher survival rates than regular echinoids following mass extinctions. This study focuses on the irregular echinoid Claviaster libycus, investigating its flow field and scour behavior under extreme water flow conditions through numerical simulations and experiments. The numerical model Splash3D used in this study was modified from the open-source code Truchas developed by the U.S. National Laboratory. Splash3D solves the three-dimensional incompressible Navier-Stokes Eqs.. The fluid volume method describes the water surface kinematics and sand surface kinematics. Since Claviaster libycus is semi-submerged in the sand, a discontinuous bi-viscosity model describes the rheological behavior of the bed material. The research findings indicate that when the gonopore of Claviaster libycus faces downstream, there is no evident horseshoe vortex flow, which contributes to reducing the occurrence of localized scour. This also validates the hypothesis of this study: the transition of echinoids from pentaradial symmetry to bilateral symmetry assists in stabilizing bottom sediments and reducing localized scour.

Mass occurrence of echinoids in an Oligocene hydrocarbon-seep limestone from the Olympic Peninsula, Washington State, USA

AbstractLoose limestone blocks of a newly recognized hydrocarbon-seep deposit from the lower Oligocene Jansen Creek Member of the Makah Formation were collected on a beach terrace close to the mouth of Bullman Creek in Washington State, USA. The limestone consists largely of authigenic carbonate phases, including 13C-depleted fibrous cement forming banded and botryoidal crystal aggregates with δ13C values as low as –23.5 ‰. Lipids extracted from the limestone yielded molecular fossils of anaerobic methanotrophic archaea (ANME), dominated by compounds of an ANME-2/DSS consortium with δ13C values as low as −106 ‰, indicating formation at an ancient methane seep. The fossil inventory of the seep deposit is remarkable, consisting almost solely of echinoid remains, whereas typical seep biota are absent. Varying preservation of the echinoid fossils indicates parautochthonous deposition, corroborated by evidence for high fluid flow at the ancient seep, possibly responsible for displacement of echinoids after death. Although a full taxonomic description of the echinoids cannot be given, almost all fossils were assigned to one taxon of irregular spatangoids, except for a single regular echinoid. Abundance and lifestyle of the irregular spatangoids in the Bullman Creek echinoid seep deposit resemble those of the fossil Tithonia oxfordiana from an upper Jurassic seep deposit in France and extant Sarsiaster griegii from modern seeps in the Gulf of Mexico. The Bullman Creek echinoid deposit probably represents a fossil analogue of the Gulf of Mexico Sarsiaster mass occurrence, indicating that the adaptation of spatangoid echinoids to chemosynthesis-based ecosystems ranges back at least to the earliest Oligocene.

Just a different place to graze? An unusual occurrence of the echinoid feeding trace Gnathichnus pentax on a marine vertebrate coprolite (Miocene, Italy) and its palaeoethological implications

Faeces produced by marine vertebrates and macro-invertebrates contain sufficient organic matter to represent a usable food source for a wide array of macroscopic animals. In some extant marine environments, coprophagy even represents a crucial trophic interaction in food webs. In ancient ecosystems, coprophagy by macroscopic animals is occasionally exemplified by coprolites that exhibit biting traces or burrows. Here, we report Gnathichnus pentax on an exquisitely preserved vertebrate-bitten vertebrate coprolite from the marine calcareous deposits of the Pietra leccese (Miocene, southern Italy). This unusual occurrence is interpreted as evidence of the feeding activity of a regular echinoid; in particular, it may represent either exploratory coprophagy or the browsing of an algal (microbial) film that locally developed on the exterior of the faeces. Strengthening the former interpretation, the development of microbial communities on submerged faeces often leads to their destruction; furthermore, some extant Antarctic echinoderms are well known to ordinarily feed on vertebrate faeces, and coprophagy is believed to be fairly widespread among sea urchins. Supporting the algal browsing hypothesis, in turn, only a limited area of the external surface of the faeces was subject to grazing, and the resulting trace is neatly defined, which suggest that the feeding sea urchin targeted a precise location on the dung's exterior when the latter was already rather firm. To our knowledge, the G. pentax specimen studied here represents the first published record of this ichnotaxon on a coprolite.

Bioerosive structures on the Pliocene rocky shores of Catalonia (Spain).

Bioerosive structures relating to rocky shores active during the Pliocene and associated pebbles in three basins at Baix Ebre Baix Llobregat and Alt Emporda areas (Catalonia, Spain) are reviewed. A high degree of uniformity exists behveen the basins from the ichnological point of view, although each one presents certain particular characteristics. The main bioerosive structures observed are the following: Entobia ichnospp.; borings of cheilostomata bryozoans of Spatipora and Terebripora types; Gastrochaenolites lapidicus and G. torpedo; Meandropolydora ichnosp.; Centrichnus eccentricus; Caulostrepsis taeniola and Caulostrepsis ichnosp.; Trypanites ichnosp.; Genatichnus pentax and bowl-shaped pits attibuted to regular echinoid activity. Apart from these bioerosive structures, the etching scars caused by cirripedes and epilithic bivalves are also common. The extensive presence of the Gastrochaenolites-Entobia ichnocenosis in Neogene rocky shores is emphasized.

Multiple phyla, one time resolution? Similar time averaging in benthic foraminifera, mollusk, echinoid, crustacean, and otolith fossil assemblages

Abstract Time averaging of fossil assemblages determines temporal precision of paleoecological and geochronological inferences. Taxonomic differences in intrinsic skeletal durability are expected to produce temporal mismatch between co-occurring species, but the importance of this effect is difficult to assess due to lack of direct estimates of time averaging for many higher taxa. Moreover, burial below the taphonomic active zone and early diagenetic processes may alleviate taxonomic differences in disintegration rates in subsurface sediments. We compared time averaging across five phyla of major carbonate producers co-occurring in a sediment core from the northern Adriatic Sea shelf. We dated individual bivalve shells, foraminiferal tests, tests and isolated plates of irregular and regular echinoids, crab claws, and fish otoliths. In spite of different skeletal architecture, mineralogy, and life habit, all taxa showed very similar time averaging varying from ~1800 to ~3600 yr (interquartile age ranges). Thus, remains of echinoids and crustaceans—two groups with multi-elemental skeletons assumed to have low preservation potential—can still undergo extensive age mixing comparable to that of the co-occurring mollusk shells. The median ages of taxa differed by as much as ~3700 yr, reflecting species-specific timing of seafloor colonization during the Holocene transgression. Our results are congruent with sequestration models invoking taphonomic processes that minimize durability differences among taxa. These processes together with temporal variability in skeletal production can overrule the effects of durability in determining temporal resolution of multi-taxic fossil assemblages.

Post-metamorphic skeletal growth in the sea urchin Paracentrotus lividus and implications for body plan evolution

BackgroundUnderstanding the molecular and cellular processes that underpin animal development are crucial for understanding the diversity of body plans found on the planet today. Because of their abundance in the fossil record, and tractability as a model system in the lab, skeletons provide an ideal experimental model to understand the origins of animal diversity. We herein use molecular and cellular markers to understand the growth and development of the juvenile sea urchin (echinoid) skeleton.ResultsWe developed a detailed staging scheme based off of the first ~ 4 weeks of post-metamorphic life of the regular echinoid Paracentrotus lividus. We paired this scheme with immunohistochemical staining for neuronal, muscular, and skeletal tissues, and fluorescent assays of skeletal growth and cell proliferation to understand the molecular and cellular mechanisms underlying skeletal growth and development of the sea urchin body plan.ConclusionsOur experiments highlight the role of skeletogenic proteins in accretionary skeletal growth and cell proliferation in the addition of new metameric tissues. Furthermore, this work provides a framework for understanding the developmental evolution of sea urchin body plans on macroevolutionary timescales.

First distribution record of regular echinoids (Echinodermata; Echinoidea) from Chennai Coast,South India

The regular echinoids were recorded from Chennai Coast,Tamilnadu, South India and the animals were belong to 4 families, 5 genera and 5 species. An identification key to generic level and synoptic description are provided. Temnopleurid sea urchin Salmaciella oligopora (Clark, 1916) was recorded for the first time in 20-30m depth between Chennai and Pondicherry Coasts, South East Coast of India. Salmaciella oligopora molecular identification was confirmed using 18S rRNA sequencing and compared to Genbank. Salmaciella oligopora nucleotide analysis in BLASTn (Basic Local Alignment Search Tool of nucleotide) result showed 99% similarity in Genbank sequences. Phylogenetic tree analysis showed a close relationship to the Temnopleudiae family. Astropyga radiata (Leske, 1778), Prionocidaris baculosa (Lamarck, 1816), Stomopneustes variolaris (Lamarck, 1816), Salmacis virgulata (L. Agassiz and Desor )1846, were recorded first time from Chennai coast.

Paleoecology of sublittoral Miocene echinoids from Sardinia: A case study for substrate controls of faunal distributions

AbstractA rich echinoid fauna within the middle Miocene carbonate sedimentary succession cropping out along the coast between Santa Caterina di Pittinuri and S'Archittu (central-western Sardinia) allows the comparison of faunal gradients and preservation potentials from both hard and soft substrata. Three echinoid assemblages are recognized. Faunal composition, as well as taphonomic and sedimentological features and functional morphological interpretation of the echinoid test indicate an outer sublittoral setting. Assemblage 1 represents a highly structured environment within the photic zone, with mobile substrata occupied by infaunal irregular echinoids, mainly spatangoids, and localized hard substrata, provided by rhodolith beds, with epibenthic regular echinoids represented by the co-occurrence of the diadematidDiademaGray, 1825 and the toxopneustidsTripneustesL. Agassiz, 1841 andSchizechinusPomel, 1869. Assemblage 2 shows a higher diversity of irregular echinoids, dominated by the clypeasteroidsEchinocyamusvan Phelsum, 1774 andClypeasterLamarck, 1801 and different spatangoids, with the minute trigonocidaridGenocidarisA. Agassiz, 1869 among regular echinoids. This assemblage points to a soft-bottom environment with moderate water-energy conditions, periodically affected by storms. A low-diversity echinoid fauna in Assemblage 3, dominated by the spatangoidsBrissopsisL. Agassiz, 1840 andOvaGray, 1825, documents a deeper, soft-bottom environment, possibly below storm-wave base. These results indicate that the diversity of echinoid faunas originating in sublittoral environments is related to: (1) the presence of both soft and hard substrata, (2) differential preservation potentials of the various echinoid taxa, (3) intense bioturbation, and (4) sediment deposition by sporadic storm events.

An annotated species list of regular echinoids from Sri Lanka with notes on some rarely seen temnopleurids.

The first recorded regular echinoid species from Sri Lanka, “Salmacis virgulatus” (now known as S. virgulata L. Agassiz in L. Agassiz & Desor, 1846), was listed by Agassiz & Desor (1846). Knowledge of Sri Lankan regular echinoids continued to advance until the end of the 19th century. However, there is a gap in knowledge between the mid-20th and the beginning of the 21st centuries due to a lack of systematic studies, with the exception of two checklists published by the IUCN Red List in 2006 and 2012. In the present study, we compiled a species list combining published data and new data based on fieldwork between 2013 and 2015. Echinoids were sampled by snorkelling, diving, examination of fisheries bycatch, and collection of tests from beaches. The updated species list presented in this study includes 39 regular echinoids belonging to 28 genera, nine families, and five orders. Phyllacanthus imperialis (Lamarck, 1816) and Temnopleurus toreumaticus (Leske, 1778), which were not recorded during the last 90 years, were confirmed to still occur in Sri Lanka by the present study. We develop an updated species list of regular echinoids to form a basis for future systematic work. The study recommends further investigation to evaluate the status of deep-sea species and additional field work off the northern and eastern coasts of Sri Lanka.

Middle Eocene echinoids from the Dammam formation of Qatar, Arabian Gulf

ABSTRACT The present article describes the Middle Eocene Echinoids fauna from the Dammam formation that has been investigated on the Ras Abrouq peninsula, near the town of Zekreet, the western part of Qatar. The circa 4 km long section where the fossils have been identified, consists of a carbonate-dominated lower part and a silica-rich calcareous upper part, corresponding to a general transgression/regression cycle. A total of 25 Echinoid species belonging to 16 genera are described. Various echinoids assemblages were distinguished, which differ with respect to the species diversity and sedimentary environment. Mainly the following two assemblages, as defined by Kroh A. and Nebelsick J. H., are represented: regular Echinoid (Phymosomatoida Order, Porosoma genus) in the lower part of the formation, ‘Spatangoid’ assemblage: it includes Schizaster, Linthia, Eupatagus, Opissaster, Hemiaster and Brissopsis genera in the lower part of the formation, ‘Cassiduloid’ assemblage: it includes Echinolampas and Petalobrissus genera in the upper part of the formation.

The internal morphology of primary spines of extant regular echinoids in the tropical western Atlantic: a SEM atlas

The spines of echinoids are common palaeontological objects, but rarely supply more than this minimal information, because they are difficult to identify to genus or species. Some taxa, particularly cidaroids, may be named based on the external morphology of their spines, but this is of no assistance when identifying spines in thin section. Yet, the internal complexities of the stereom of the echinoid spine may be unique to a particular species or, at least, genus or family. A scanning electron micrograph (SEM) atlas of the internal structure of the primary spines of 14 of the most common species of regular echinoids from shallow–water environments of the tropical western Atlantic Ocean is presented herein. This demonstrates the stereom structure of the spines of each of these species by reference to multiple images. Plates of SEMs are supplemented by brief descriptions and comparisons. This atlas is intended as a tool that can be applied to diverse aspects of palaeontological and sedimentological studies in thin section.

Macrobioerosion and Microbioerosion in Marine Molluscan Shells from Holocene and Modern Beaches (39°–40°S, South of Buenos Aires Province, Argentina)

AbstractThe marine sediments of the area of Verde Peninsula – Jabali Island (39°28′S/62°19′W–40°28′S/62°11′W) Holocene in age (3–2 ky), and modern beaches contain a significant amount of bioeroded mollusc shells. Fifteen sites were analyzed, in which 20.11% of the mollusc shells (2168 valves) presented bioerosion traces, in 54 species (30 bivalves and 24 gastropods). Fourteen ichnogenera were reported: Entobia, Maeandropolydora, Iramena, Caulostrepsis, Pennatichnus, Pinaceocladichnus, Trypanites, and Gastrochaenolites (Domichnia), Gnathichnus and Radulichnus (Pascichnia), Finichnus and Centrichnus (Fixichnia), Oichnus (Praedicnia) (macrobioerosion), y Semidendrina (microbioerosion), the latter is first reported in mollusc shells in Argentina. Eleven ichnospecies were identified Finichnus peristroma, Maeandropolydora sulcans, Gnathichnus pentax, Pinaceocladichnus onubensis, Caulostrepsis taeniola, Centrichnus eccentricus, Radulichnus inopinatus, Oichnus simplex, Oichnus paraboloides, Oichnus gradatus, and Gastrochaenolites torpedo (lithic remains). The dominant ichnogenera in the Holocene deposits are Iramena, Entobia and Oichnus. The same ichnogenera are constant with different abundance in the modern beaches, and increasing representation of Pinaceocladichnus and Pennatichnus. The dominant ichnofacies in the Holocene deposits is Trypanites, revealing a benthonic marine community composed of cheilostome bryzoans, clionaid sponges, predator gastropods, regular echinoids, polychaete annelids, bivalves, thallophytas and fungi. Generally, the area was described as a sublittoral, low‐energy, stable environment with high rate of oxygenation, and sandy bottoms, with rocky bottoms at Villalonga locality.

Predation on feather stars by regular echinoids as evidenced by laboratory and field observations and its paleobiological implications

AbstractAmong extant crinoids, the feather stars are the most diverse and occupy the greatest bathymetric range, being especially common in reef environments. Feather stars possess a variety of morphological, behavioral and physiological traits that have been hypothesized to be critical to their success, especially in their ability to cope with predation. However, knowledge of their predators is exceptionally scant, consisting primarily of circumstantial evidence of attacks by fishes. In this study the question whether regular echinoids, recently shown to consume stalked crinoids, also consume feather stars is explored. Aquarium observations indicate that regular echinoids find feather stars palatable, including feather stars known to be distasteful to fish, and that regular echinoids can capture and eat live feather stars, including those known to swim. Gut-content analyses of the echinoidAraeosoma fenestratum(Thomson, 1872), which is commonly observed with large populations of the feather starKoehlermetra porrecta(Carpenter, 1888) in video transects from marine canyons off the coast of France, revealed elements of feather stars in the guts of 6 of 13 individuals. The high proportion of crinoid material (up to 90%), and the presence of articulated crinoid skeletal elements in the gut ofA. fenestratum, suggest that these echinoids consumed at least some live crinoids, although they may have also ingested some postmortem remains found in the sediment. Additionally, photographic evidence from the northeast Atlantic suggests that another regular echinoid,Cidaris cidaris(Linnaeus, 1758), preys on feather stars. Thus in spite of the broad suite of antipredatory adaptations, feather stars are today subject to predation by regular echinoids and may have been since the Mesozoic, when this group of crinoids first appeared.

Echinoid Bite Traces on Late Cretaceous (Early Maastrichtian) Sea Lilies from Southern Poland

Abstract. Echinoid bite traces on Late Cretaceous (early Maastrichtian) bourgueticrinids and isocrinids of southern Poland (Miechow Trough) were documented. The bitten sea lilies co-occurred with Goniopygus, a regular echinoid possessing an Aristotle's lantern. This is the first record of Goniopygus in the lower Maastrichtian of Poland. Considering former studies, as well as direct in situ observations of extant sea lilies and sea urchin behavior, the traces at hand could be most likely linked with predatory actions of the Goniopygus echinoid. Such studies on predatory phenomena are crucial and could provide baseline data concerning the evolutionary trends among organisms engaged in the “arms race”.

Macroinvertebrate fauna and depositional environment of the lower Upper Cenomanian Oberhäslich Formation in the Saxonian Cretaceous Basin (Germany)

In Saxony (southeast Germany), the global early Late Cretaceous transgression is reflected by the onlap of shallow-marine siliciclastics of the lower Upper Cenomanian Oberhäslich Formation (Calycoceras naviculare Zone) onto the eastern Erzgebirge, the central part of the emergent Mid-European Island. Based on detailed logging of sections south of Dresden and the study of extensive collection material, the depositional environment and macroinvertebrate assemblages of the Oberhäslich Formation have been reconstructed. This unit, with a mean thickness of 10–15m, usually shows a fining-upward trend that may become reversed towards the top, was laid down in a single 3rd-order sea-level cycle and is capped by an unconformity at the base of the overlying upper Upper Cenomanian Dölzschen Formation (sequence boundary Cenomanian 5; junction of the Calycoceras naviculare and Metoicoceras geslinianum zones). The macroinvertebrate assemblage of the Oberhäslich Formation, collected mainly from bioturbated, fine- or rarely medium-grained, quartz-rich sandstones, is fairly diverse, comprising nearly 50 taxa, predominantly bivalves (94.3%). Most conspicuous and abundant are relatively large forms such as Rhynchostreon (R.) suborbiculatum (25%) and Inoceramus pictus spp. (21%), eponymous taxa of the Rhynchostreon suborbiculatum/Inoceramus pictus assemblage. Non-bivalve benthic invertebrates are rare and represented by rather poorly preserved irregular and regular echinoids, siliceous sponges, a few gastropods, crustacean remains and a single starfish. Common Thalassinoides and Ophiomorpha burrows indicate that crustaceans were an important part of the infauna. Pervasive bioturbation resulted in a post-depositional homogenization of the sediments while all body fossils are preserved as (composite) internal moulds. The guild structure of the Rhynchostreon suborbiculatum/Inoceramus pictus assemblage shows a predominance of epifaunal and semi-infaunal suspension feeders (95.3%), suggesting eutrophic and unstable “green-water conditions” of an inner-shelf setting. Deposit-feeding biota are rare. The common occurrence of articulated bivalves and storm-induced shell beds indicate episodic rapid burial, most probably by tempestites. A current-influenced, well-oxygenated and nutrient-rich environment slightly below fair-weather base is inferred for the fine-grained sandy, fossiliferous sediments of the Oberhäslich Formation.

British Jurassic Regular Echinoids Part 2, Carinacea

Part 2 completes the description of the regular echinoids of the British Jurassic. Members of the orders Phymosomatoida, Salenioida, Stomopneustoida and Arbacioida are covered, with 25 genera and 4...

Covering behavior of deep-water echinoids in Antarctica: possible response to predatory king crabs

Covering behavior refers to the propensity of echinoids (Echinoidea) to lift materials from the surrounding environment onto their aboral surfaces using their tube feet and spines. This behavior has been widely documented in regular echinoids from a variety of well-lit, shallow- marine habitats. Covering behavior in the deep sea, however, is rarely observed, and the functional significance of covering when it does occur remains speculative. During a photographic survey of the seafloor off Anvers Island and Marguerite Bay along the western Antarctic Pen - insula, we imaged 11 benthic transects at depths ranging from 390 to 2100 m. We recorded the number of echinoid species, incidence of covering behavior, types of materials used for covering, potential predators of echinoids, and potential prey items for predators. The echinoid Sterechinus spp. was found at all depths, and the percentage of individuals exhibiting covering behavior increased with depth between 390 and 1500 m. There was a significant positive correlation between the incidence of covering behavior in Sterechinus spp. and the density of king crabs (Anomura: Lithodidae), crushing predators that may be expanding their bathymetric range up the Antarctic continental slope as a consequence of ongoing climatic warming. In contrast, covering behavior was not positively correlated with the densities of non-crab predators, the total densities of predators, or the availability of prey. Our results document rarely observed covering behavior in echinoids living in the deep sea and suggest that covering could be a behavioral response to predation pressure by king crabs.

Revision of Cenomanian regular echinoids in collections at the Cairo Geological Museum, Egypt

Cenomanian rocks of Egypt are rich in moderately to well-preserved echinoids. From the large Cretaceous echinoid collection at the Cairo Geological Museum, a total of 27 regular species, in 12 genera, eight families, six orders and two subclasses, are revised and systematically described from these strata as exposed at several localities in Egypt. One new family (Pedinopsidae), one new subfamily (Lorioliinae), one new genus (Alternocidaris) and two new species of Goniopygus, G. subaequalis (Gebel Ekma) and G. macrotuberculatus (Gebel El Minsherah), are erected. Additionally, two species of Diplopodia, D. micropyga Fourtau, 1921 and D. halperti Fourtau, 1921, are transferred to the genus Pedinopsis.

The reproductive cycle of the sea urchin Lytechinus variegatus (Echinodermata: Echinoidea) in southern Brazil

Lytechinus variegatus (Lamarck) is a common echinoid found on the Atlantic coast of America from North Carolina to southern Brazil and their populations inhabit sub littoral shallow-water environments. This research examined some aspects of reproduction in the southern limit of distribution of the species. A total of 86 adult individuals of L. variegatus (50.8 to 77.0 mm test diameter) were manually collected from September 2000 to September 2001 along the unconsolidated bottoms at the eurihaline sector of Paranagua Bay (48° 19’ W - 25° 35’ S) for histological characterization of gametogenesis, sex ratio and gonadal index (GI) evaluation. This population showed a synchronicity in maturation and spawning events (autumn and winter respectively), with a 1:1 sex ratio (χ2 = 2.57, df = 7, p < 0.05). The GI increase was associated with storage of nutritional resources periods (resting stages and proliferation) that occurred between late winter and spring. Biometric analyzes indicated a greater investment in size and/or quantity of gametes between late spring and summer, when it was possible to observe mature sperm occupying on average 63.9 % of the follicular lumen and oocytes reaching values of 70.0 to 75.0 μm. Mature oocyte mean size is the highest diameter of those developed by other regular echinoids in the same latitude. However, the average diameter of mature oocytes of L. variegatus in the southern limit of its distribution was lower than the values recorded for the northern hemisphere.