identifier	taxonID	type	CVterm	format	language	title	description	additionalInformationURL	UsageTerms	rights	Owner	contributor	creator	bibliographicCitation
2C7FBF6B6C3A59A3B13A94EF277788FF.text	2C7FBF6B6C3A59A3B13A94EF277788FF.taxon	http://purl.org/dc/dcmitype/Text	http://rs.tdwg.org/ontology/voc/SPMInfoItems#GeneralDescription	text/html	en	Ephydatia fluviatilis (Linnaeus 1759)	<div><p>Ephydatia fluviatilis (Linnaeus, 1759)</p><p>Figs 3, 5</p><p>Synonymy and references.</p><p>Clypeatula cooperensis Peterson &amp; Addis, 2000, Ephydatia fluviatilis chui Gee, 1926, Ephydatia fluviatilis hastifera Rezvoj, 1930, Ephydatia fluviatilis intha Annandale, 1918, Ephydatia fluviatilis teberdana Rezvoj, 1928, Ephydatia fluviatilis var. capensis Kirkpatrick, 1907, Ephydatia fluviatilis var. himalayensis Annandale, 1912, Ephydatia goriaevii Swartschewsky, 1901, Meyenia fluviatilis (Linnaeus, 1759), Meyenia fluviatilis var. angustibirotulata Carter, 1885, Meyenia fluviatilis var. gracilis Carter, 1885, Meyenia mexicana Potts, 1885, Spongilla fluviatilis Linnaeus, 1759, Spongilla fluviatilis (Linnaeus, 1759), Spongilla pulvinata Lamarck, 1816, Spongilla sceptrifera Bowerbank, 1874, Spongilla stagnalis Dawson, 1875 .</p><p>Type locality.</p><p>The Netherlands, Western Palearctic Region (Penney and Racek 1968).</p><p>Material examined.</p><p>• CNPGG -2670, <a href="https://tb.plazi.org/GgServer/search?materialsCitation.longitude=-89.5881&amp;materialsCitation.latitude=20.5801" title="Search Plazi for locations around (long -89.5881/lat 20.5801)">Cenote Sabak-Ha</a>, Sacalum, Yucatan, Mexico (20.5801 ° N, 89.5881 ° W), 4 m deep, collected by Victor Eduardo Gómez Bretón, March 3 rd 2024 ; • CNPGG -2671, <a href="https://tb.plazi.org/GgServer/search?materialsCitation.longitude=-89.5881&amp;materialsCitation.latitude=20.5801" title="Search Plazi for locations around (long -89.5881/lat 20.5801)">Cenote Sabak-Ha</a>, Sacalum, Yucatan, Mexico (20.5801 ° N, 89.5881 ° W), 11 m deep, collected by V. E. Gómez Bretón, March 3 rd 2024 ; • CNPGG -2673, <a href="https://tb.plazi.org/GgServer/search?materialsCitation.longitude=-89.4031&amp;materialsCitation.latitude=20.6403" title="Search Plazi for locations around (long -89.4031/lat 20.6403)">Cenote Suhem</a>, Pixya, Yucatan, Mexico (20.6403 ° N, 89.4031 ° W), 5.3 m deep, collected by V. E. Gómez Bretón, March 29 th 2025 .</p><p>Distribution.</p><p>Canada (Dawson 1875; Ricciardi and Reiswig 1993), China (Gee 1926; Zhang 1948), Himalaya (Annandale 1912), Estonia (Roovere et al. 2006), Germany (Linnaeus 1759), France (Topsent (1930)), Ireland (Stephens 1920), Italy (Cardone 2014), Mexico (Potts 1885 a), Myanmar (Annandale 1918), Netherlands (Vorstman 1954; Van Soest 2025), Poland (Linnaeus 1759), South Africa (Kirkpatrick 1907; Manconi 2008), Sweden (Linnaeus 1759), United Kingdom (Evans and Montagnes 2019), United States (Lauer and Spacie 1996; Manconi and Pronzato 2016), Russia (Schletterer and Eggers 2006), Spain (Gost et al. 2023).</p><p>External description.</p><p>In Sabak-Ha Cenote, the sponge exhibits a predominantly massive encrusting morphology, creating prominent mounded structures and frequently developing into distinctive discoidal formations. In contrast, specimens from the Suhem cenote present as diminutive, attenuated, and irregularly encrusting forms (Figs 3, 5). Smooth and porous texture. The consistency of the living sponge is fragile and easily brittle upon contact. Oscula not visible to the naked eye. Exhibiting two colors in vivo, greenish yellow in the presence of light and dull pinkish in its absence (Fig. 3). Whitish color when preserved in alcohol.</p><p>Skeleton.</p><p>Forming paucispicular tracts, composed of 2–5 intersecting oxea spicules producing regular mesh (Fig. 6 D). The tracts form an alveolate structure, clearly forming rounded meshes. Spongin is generally scarce but present in most tracts.</p><p>Gemmules.</p><p>Gemmules scarce and scattered, hemispherical measuring 200.56 (190.77–210.36) μm in diameter (Fig. 6 A). Gemmules were observed exclusively in specimens from Suhem Cenote.</p><p>Spicules.</p><p>Megascleres consist primarily of smooth oxeas that are slender and slightly curved at the midpoint, occurring in two distinct size categories. Oxeas I are the most common spicules in specimens from both cenotes, measuring 327.13 (243.28–373.53) μm × 15.15 (10.09–19.71) μm (Fig. 6 B). Oxeas II are much less frequent than type I and are noticeably shorter and thinner, measuring 172.55 (147.27–199.68) μm × 4.7 (3.77–5.14) μm. These measurements were obtained from the total number of spicules measured in specimens CNPGG -2670 (Fig. 3 C), CNPGG -2671 (Fig. 3 D) from the Sabak-Ha Cenote and CNPGG -2673 (Fig. 5 C) from the Suhem Cenote.</p><p>Additionally, smaller and less abundant spiny oxeas were observed; these are mostly straight and were found exclusively in specimen CNPGG -2670 from the Sabak-Ha Cenote. They measure 110.71 (88.92–132.51) μm × 10.13 (9.10–11.17) μm (Fig. 6 C).</p><p>Gemmuloscleres consist of birotules with spined shafts and rotules of nearly identical morphology at both extremities (Figs 6 F, 7), measuring 46.76 (32.66–72.96) μm × 7.04 (4.64–10.15) μm. The rotules have a diameter of 23.41 (19.18–31.74) μm (Fig. 6 G). This size range was obtained from the total number of gemmulosclere birotules measured in all three collected specimens: CNPGG -2670 and CNPGG -2671 from the Sabak-Ha Cenote, and CNPGG -2673 from the Suhem Cenote. Detailed measurements for each specimen are provided in Table 1.</p><p>Molecular results.</p><p>The molecular analyses using Bayesian and Maximum Likelihood methods yielded congruent topologies, revealing a well-supported monophyletic clade containing specimens together with Ephydatia fluviatilis, confirming species-level identification (Fig. 8). Sequences from both cenotes (Sabak-Ha and Suhem) were identical in nucleotide composition, and BLAST searches against GenBank confirmed assignment to Spongillida ( Porifera), with our samples differing by less than 3 % from reference sequences of E. fluviatilis . This clade clustered as sister to a monophyletic group formed by Heterorotula (Penney &amp; Racek, 1968) and Racekiela (Bass &amp; Volkmer-Ribeiro, 1984), with both clades sister to the main Ephydatia assemblage. The genera Eunapius (Gray, 1867) and Spongilla (Lamarck, 1816) were recovered as monophyletic, while Trochospongilla and Radiospongilla remained unresolved.</p><p>Remarks.</p><p>The morphological and molecular results strongly support the assignment of the specimens to the genus Ephydatia . First, BLAST-based molecular analyses confirmed the identity of our specimens within the Spongillidae family, revealing that the samples present a divergence of less than 3 % from Ephydatia fluviatilis . This low genetic divergence is common in the E. fluviatilis group and indicates a very close relationship (Zhao et al. 2023). The molecular assignment was solidified through phylogenetic reconstruction, where the trees obtained by Maximum Likelihood (ML) and Bayesian Inference (BI) were congruent, demonstrating that the sponges from both cenotes consistently cluster together and form a robust clade alongside Ephydatia fluviatilis . In this grouping, the E. fluviatilis group was positioned as a sister group to monophyletic clades composed of the genera Heterorotula (Penney &amp; Racek, 1968) and Racekiela cresciscrystae (Gómez, Carballo, Cruz-Barraza &amp; Camacho-Cancino, 2019) . This particular topology is notable as it is consistent with previous studies on Spongillida phylogeny based on ITS sequences and underscores the taxonomic complexity of the group (Gómez et al. 2019; Itskovich et al. 2022; Zhao et al. 2023).</p><p>Regarding morphology, the genus Ephydatia is characterized by birotules with short shafts, rotules of equal diameter, and megasclere oxeas that may be either microspined or smooth (Manconi and Pronzato 2002), all features observed in our specimens. In addition, the morphology of the collected specimens is consistent with the bulbous and corrugated, flat encrustating and discoidal typical growth forms reported for E. fluviatilis (Penney and Racek 1968; Pronzato and Manconi 1995; Lopp et al. 2007).</p><p>In terms of spicule dimensions, the length of smooth oxeas I (243.28–373.53 µm) falls within the range reported in the original species description (210–400 µm) (Penney and Racek 1968). Notably, the specimen CNPGG -2670 (Fig. 3 C) from Sabak-Ha also possessed uncommon, smaller, more heavily spined oxeas not previously documented in the literature. In addition, dimensions showed interpopulation variation, specimens from Sabak-Ha cenote exhibited longer birotules (44.65–72.96 µm) than the typical range for E. fluviatilis (26–30 µm), while those from Suhem Cenote are more closely related to the expected range (32.66–43.15 µm) (Fig. 7) (Table 1). This variation suggests that site-specific environmental conditions within each cenote may influence spicule formation and growth, consistent with previous reports of this species sensitivity to changes in alkalinity and light intensity (Gost et al. 2023).</p><p>About the presence of spines in birotules, some studies have revealed them as response to the water chemistry, spine development has been linked to habitats with elevated chloride concentrations and high alkalinity (Poirrier et al. 1974), conditions characteristic of cenote ecosystems (Pérez-Ceballos et al. 2012; Cruz-Sánchez et al. 2018). These conditions allow the spination in birotules of E. fluviatilis in cenote ecosystems.</p><p>In North America, in addition to E. fluviatilis, the species E. robusta (Potts, 1888), E. millsii (Potts, 1888), E. muelleri (Lieberkühn, 1856), and E. subtilis (Weltner, 1895) have been reported (Carter 1885; Potts 1885 b; Potts 1888; Weltner 1895; Smith 1918) (Fig. 9). However, descriptions of E. robusta, E. millsii, and E. subtilis remain outdated and have not been revised since their original descriptions. E. robusta was described as having large birotules with cylindrical or conical shafts bearing long spines (Potts 1888), while E. millsii presents symmetrical birotules with nearly cylindrical shafts bearing a single median spine (Potts 1888). The identity of E. subtilis remains uncertain (Weltner 1895; Harrison 1979). In contrast, E. muelleri is the only species with recent molecular and updated morphological data (Lopp et al. 2007; Kenny et al. 2020). E. fluviatilis is morphologically similar to E. muelleri, differing mainly in birotule shaft length and oxeas spination (Lopp et al. 2007), although their genetic relationship remains unclear (Zhao et al. 2023).</p><p>These limitations highlight gaps in species delimitation, as morphological differences are largely based on the presence or absence of spines on oxeas or birotule shafts. Given the wide distribution of E. fluviatilis across freshwater habitats in the Northern Hemisphere (Oscoz et al. 2009; Lucentini et al. 2013; Erpenbeck et al. 2020), integrative studies combining molecular and morphological data are required to improve species delimitation in this region and across the genus range (Fig. 9). Zhao et al. (2023) suggested that E. fluviatilis represents a species complex, with birotule shaft length being more informative than spine presence. Our morphological and molecular data support this view, indicating that shaft spines in Yucatan cenote populations reflect environmentally induced variation rather than species-level diagnostic characters.</p></div>	https://treatment.plazi.org/id/2C7FBF6B6C3A59A3B13A94EF277788FF	Public Domain	No known copyright restrictions apply. See Agosti, D., Egloff, W., 2009. Taxonomic information exchange and copyright: the Plazi approach. BMC Research Notes 2009, 2:53 for further explanation.		Pensoft via Plazi	Hernández-Solis, Pablo Alberto;Gómez-Bretón, Víctor Eduardo;de la Cruz-Fernández, Dalia Angélica;Simões, Nuno	Hernández-Solis, Pablo Alberto, Gómez-Bretón, Víctor Eduardo, de la Cruz-Fernández, Dalia Angélica, Simões, Nuno (2026): New discovery of the freshwater sponge Ephydatia fluviatilis (Linnaeus, 1759) in cenote ecosystems of Yucatan, Mexico: Morphological and molecular insights. Subterranean Biology 55: 109-136, DOI: 10.3897/subtbiol.55.177524
