The first taxonomic descriptions of the sponge diversity at El Pelado Marine Protected Area in the province of Santa Elena, Ecuador is reported. Tedania (Tedania) ecuadoriensis Jaramillo & Hajdu, sp. nov. is described from its shallow waters. In addition, Callyspongia (Callyspongia) aff. californica (sensu Cruz-Barraza and Carballo 2008; non sensu Dickinson 1945) and Cliona aff. euryphylle are reported for the first time. The former species is likely distributed over 4,000 km along the Tropical Eastern Pacific, whereas the latter might be an example of a trans-isthmian lineage. An amended diagnosis for Callyspongia (Callyspongia) and an updated identification key for the subgenera of Callyspongia are provided.

Callyspongia, Cliona, sponge taxonomy, Tropical Eastern Pacific

Sponges represent a key component of marine ecosystems and exhibit high diversity and abundance in some oceans, including tropical, temperate and polar regions (Bell and Barnes 2003; Bell and Smith 2004; Carballo et al. 2008; Hajdu et al. 2013; Hajdu et al. 2015; Pacheco et al. 2018). Due to the broad substrate cover and filtration capacity of sponges, marine ecosystems in general will likely be affected by changes in the geographic distribution of these organisms (Bell and Smith 2004; Bell 2007; Carballo et al. 2008; Cruz-Barraza and Carballo 2008). These reasons, together with sponges’ known biomedical potential, have attracted the interest of researchers to explore the distribution and diversity of sponges in maritime ecoregions around the planet.

Despite published reports on sponge distribution in the Pacific Ocean, knowledge gaps still exist in the eastern Pacific, and especially along the coast of Ecuador, where descriptive studies have rarely been conducted (Miloslavich et al. 2011). A recent increase in taxonomic effort in this large area started in Chile (Hajdu et al. 2006; Azevedo et al. 2009; Willenz et al. 2009; Hajdu et al. 2013; Fernandez et al. 2016; Costa et al. 2020), and more recently expanded to the Peruvian coast (Aguirre et al. 2011; Azevedo et al. 2015; Hajdu et al. 2015; Cóndor-Luján et al. 2019; Recinos et al. 2020). This collective effort has unveiled a high diversity and abundance of sponges in shallow south-eastern Pacific waters. Since 2003 in Chile, and 2007 in Peru, nearly 3,000 specimens have been collected, with new species reported. Taxonomic identifications of this large collection are still in progress and will certainly lead to many more discoveries.

In this regard, and despite its shorter coastline when compared to Chile and Peru, mainland Ecuador is likely to house a significant diversity of marine sponges. In part, this will be a consequence of being situated in a convergence zone of two different oceanic currents, the northern warm Panama or El Niño Current, and the southern cold Humboldt or Peru Current (Chavez and Brusca 1991; Fiedler et al. 1992; Glynn 2003). In addition, the presence of varied marine coastal ecosystems, such as mangroves, bays, estuaries, and rocky coasts in this area, also supports this hypothesis. So far, knowledge of the sponge biodiversity of Ecuador is entirely restricted to descriptions of species from the Galapagos Islands (Desqueyroux-Faúndez and van Soest 1997; Bustamante et al. 2002). According to the World Porifera Database (WPD), 87 species have been recorded from these islands (van Soest et al. 2020), both from the shallow waters (Topsent 1895; Wilson 1904; Lendenfeld 1910; de Laubenfels 1939; Lee 1987; Hajdu and Desqueyroux-Faúndez 1994; Desqueyroux-Faúndez and van Soest 1996, 1997; Sarà et al. 2000) and deeper waters (Schuster et al. 2018). Surprisingly, no taxonomic study focused on the sponge diversity of coastal mainland Ecuador, a gap due to a historical lack of baseline scientific initiatives and sponge taxonomists in this region. In order to start reverting this scenario, a national project was funded by the Ecuadorian government aiming at the description of the marine invertebrate biodiversity, and their associated chemical and microbial diversity, in a small marine protected area of the peninsula of Santa Elena, named El Pelado Marine Reserve (REMAPE). The first results of this biodiversity assessment have recently been published with a focus on zoantharians (Jaramillo et al. 2018), and sponges come next, also selected for their known content of metabolites with potential pharmacological use (Carroll et al. 2019). The goal of the present study was therefore to describe the most abundant species of sponges occurring in the El Pelado MPA. Herein, we present three new records of Demospongiae for this area, including one new species.

This work represents the first morphological study of sponges off the coast of mainland Ecuador. As a result, we revealed two new records for the Ecuadorian mainland coast, and the South-eastern Pacific, and one new species Tedania ecuadoriensis sp. nov., provisionally endemic of the MPA El Pelado, at the Guayaquil Marine Ecoregion, Tropical Eastern Pacific Realm.

Information and interest in Ecuadorian sponges have increased in recent years as a consequence of the growing body of evidence on the marked underestimation of sponge biodiversity in the whole SE Pacific (e.g., Azevedo et al. 2009, 2015; Hajdu et al. 2013). Increasingly, this renewed interest in the biodiversity inventory of this broad area has been conducted via an integrative approach, by combining classical morphological techniques with an assessment of several molecular markers (De Paula et al. 2012; Azevedo et al. 2015). This will be the way to progress if a sound increase in knowledge on Ecuadorian marine sponges is sought. This is made clear by the partial identifications put forward here for Callyspongia aff. californica and Cliona aff. euryphylle. The final conclusive identification of these species depends on the integration of alternative data sources, which has not been possible here for several reasons: missing type materials, lack of well-preserved topotypical specimens, failure to obtain sequences from the ideal molecular markers, and time constraints.

The hesitant species determination provided here for C. aff. euryphylle and C. aff. californica derive in the first place from the insufficient data available for the type specimens of both species. The lack of type data meant that despite how similar Ecuadorian data was to more recent comprehensive records of both species, we could not conclusively identify both. Only molecular evidence can confirm these possibly discontinuous distributions, as verified for C. celata Grant, 1826 in the Western Atlantic (De Paula et al. 2012; Gastaldi et al. 2018), or the calcareous sponge Clathrina aurea Solé-Cava, Klautau, Boury-Esnault, Borojevic & Thorpe, 1991, formerly endemic to Brazil, but recently recorded from Peru (Azevedo et al. 2015) and the Caribbean (Fontana et al. 2018). Whether subsequent Mexican records of C. californica (e.g., Carballo et al. 2004, 2008; Vega 2012) are indeed conspecific with the type specimen of this species, we cannot say. We feel confident though, that the Ecuadorian specimens are conspecific to these subsequent Mexican records of C. californica, all of which we suggest being provisionally best referred to as C. aff. californica.

Despite the value of the integrative approach to systematics to correctly delimit species (e.g., Schlick-Steiner et al. 2010), a conclusive application of characters other than morphological is often impossible for the type materials. Integrative approaches are also hindered by lack of any alternative data for the type species in a genus, or for any other more closely related species, whatsoever. Our efforts to integratively describe the species presented here were unsuccessful. Nevertheless, we argue this is the way to move forward in the taxonomic study of Ecuadorian sponges, and beyond this, we recommend sponge taxonomists to turn integrative taxonomy into routine work, so, as a community, we can build a reference dataset to help determine the true extent of relatedness among sponge lineages.

Ecuador is a rare, if not unique, example of nation where 97% (87 of 90 recorded species) of the knowledge of the poriferan biological resource, mainly composed of Demospongiae, is derived from an offshore location (Schuster et al. 2018, van Soest et al. 2020). Irrespective of the biological importance of the Galapagos Archipelago, this fact needs a major reversal. It is doubtful that there will ever be a proliferation of research institutes in the archipelago that might deepen the study of several aspects of these holobionts, whose transfer to mainland Ecuador is unlikely, at the least. Getting to know more the easily accessible sponges from the coast of mainland Ecuador is essential to develop this scientific field in the country, as highlighted from pioneering bioprospecting conducted at Reserva Marina El Pelado (Calabro et al. 2018).

The rather localized distributional data generated in this study does not permit to establish biogeographic boundaries for marine sponges along the Ecuadorian mainland. These will ultimately depend on expanding the taxonomic inventory to additional localities to the S and N of MPA El Pelado. Nevertheless, present data help filling in an important knowledge gap on the distribution of Tropical Eastern Pacific sponges, by expanding the notoriously underestimated sponge biodiversity inventory into the Guayaquil Ecoregion. It is expected that sponges will produce patterns similar to those recently reported for Ecuadorian zoantharians (Jaramillo et al. 2018), where Panamanian and Humboldtian affinities are clearly evident, indicating species coming from the north, and from the south, respectively. The first of these patterns is apparent for C. aff. californica, known all the way up to Mexico, at least. However, species illustrating affinities to the colder South American Pacific, as well as to the Galapagos Islands remain to be spotted on coastal mainland Ecuador marine sponges.

This work was funded by the Secretaría de Educación, Ciencia y Tecnología e Innovación of Ecuador (SENESCYT) in the framework of the PIC-14-CENAIM-001 Project “Caracterización de la Biodiversidad Microbiológica y de Invertebrados de la Reserva Marina “El Pelado” a escalas taxonómica, metabolómica y metagenómica para su uso en Salud Humana y Animal”. K.J. acknowledges NUI Galway for supporting part of her Ph.D. scholarship, but also the Project National Marine Biodiscovery Laboratory through a grant from the Marine Institute PBA/MB/16/01. E.H. is funded by the Brazilian National Council for Scientific and Technological Development (CNPQ), by Coordination of Superior Level Staff Improvement (CAPES), and Carlos Chagas Filho Research Support Foundation (FAPERJ). Authors would like also to thank J.L. Carballo (Universidad Nacional Autónoma de México) for kindly sending the Mexican voucher of C. californica; Pierce Lalor (senior technician at NUI-Galway), and Camila Messias and Beatriz C.A. Cordeiro (technicians at Dept. of Invertebrates), who assisted us with the acquisition of SEM images, respectively at the Center for Microscopy and Imaging (CMI) – NUI Galway and the Center for Scanning Electron Microscopy of Museu Nacional/UFRJ; and Kathy Omura (Natural History Museum of Los Angeles) for her efforts in trying to locate the type material of Callyspongia californica.