Although sponges are important components of benthic ecosystems of the Caribbean Sea, their diversity remained poorly investigated in the Lesser Antilles. By organizing a training course in Martinique, we wanted both to promote taxonomy and to provide a first inventory of the sponge diversity on this island. The course was like a naturalist expedition, with a field laboratory and a classroom nearby. Early-career scientists and environmental managers were trained in sponge taxonomy. We gathered unpublished data and conducted an inventory at 13 coastal sites. We explored only shallow water habitats (0–30 m), such as mangroves, reefs or rocky bottoms and underwater caves. According to this study, the sponge fauna of Martinique is currently represented by a minimum of 191 species, 134 of which we could assign species names. One third of the remaining non-identified sponge species we consider to be new to science. Martinique appears very remarkable because of its littoral marine fauna harboring sponge aggregations with high biomass and species diversity dominating over coral species. In mangroves, sponges cover about 10% of the surface of subtidal roots. Several submarine caves are true reservoirs of hidden and insufficiently described sponge diversity. Thanks to this new collaborative effort, the Eastern Caribbean has gained a significant increase of knowledge, with sponge diversity of this area potentially representing 40% of the total in the Caribbean Sea. We thus demonstrated the importance of developing exploratory and educational research in areas historically devoid of biodiversity inventories and systematics studies. Finally, we believe in the necessity to consider not only the number of species but their distribution in space to evaluate their putative contribution to ecosystem services and our willingness to preserve them.

Most biological groups are still longing for a phylogenetically sound taxonomic organization. In this article, we aimed to verify the consistency of morphological characters in calcarean sponges of the well-known non-monophyletic order Clathrinida using a molecular phylogeny. For this we included 50 species, including six type species, currently assigned to eight different genera. A maximum likelihood topology was generated for the nuclear ITS marker using the General Time Reversible model and the bootstrap reliability test. Our topology indicated 10 clathrinid clades that included species with consistent morphological characters. In the present study, we defined nine of these clades as clathrinid genera, including four newly described and two newly diagnosed genera. Recent studies have indicated that not much phylogenetic information may be found in morphology, but our findings contradict this general assertion. Our study confirms the suitability of skeleton and body anastomosis as valid characters in a phylogenetically sound taxonomy for the order. Interestingly, we have also found that, apart from the Calcinea/Calcaronea split and a few minor details, Haeckel’s original proposal is remarkably similar to our own, which was based on a molecular phylogeny 140 years later.

Marine bioinvasions are potential threats to biodiversity and ecosystems services, being one of the major environmental, human health and socio-economic problems throughout the world. In 2005, a sponge species never reported before to the Atlantic Ocean was detected in Rio de Janeiro (Brazil). This species was initially considered new to science and in less than a decade its populations became very abundant and widespread in the Brazilian coast. In the present work, we performed detailed morphological and molecular analyses of this supposedly new species and found out that it is in fact the Indo-Pacific calcareous sponge Heteropia glomerosa (Bowerbank, 1873 Bowerbank, J. S. (1873). Contributions to a General History of the Spongiadae. Part IV. Proceedings of the Zoological Society of London, 44, 768–725. https://doi.org/10.1111/j.1096-3642.1876.tb02614.x [Crossref] , [Google Scholar] ). Heteropia glomerosa is the third alien species of calcareous sponge reported in the Atlantic and the second one that allegedly came from the Indo-Pacific. To confirm the taxonomic identification of the Atlantic specimens, we used morphological and molecular tools and re-described the holotypes of H. glomerosa and Uteopsis argentea (Poléjaeff, 1883 Poléjaeff, N. (1883). Report on the Calcarea dredged by H.M.S. ‘Challenger’, during the years 1873–1876. Report on the Scientific Results of the Voyage of H.M.S. ‘Challenger’, 1873–1876. Zoology, 8, 1–76. [Google Scholar] ). We discuss the possibility that biofouling is the introduction source for sponges and present the known distribution of H. glomerosa. Moreover, we verified that H. glomerosa fits seven out of 10 criteria proposed for recognizing alien species. Although this species can be recognized as introduced in the Atlantic Ocean, studies on population genetics, phylogeography, reproduction strategies, larval behaviour, and ecology will be necessary to allow a better evaluation of its invasive potential.

Calcareous sponges of the subclass Calcinea from Martinique (Caribbean Sea) are presented under an integrative perspective (morphology and DNA: ITS and C-LSU). Eleven species of six genera have been found in Martinique, three of them being new to science: Borojevia crystallina sp. nov., Clathrina delicata sp. nov., and Ernstia adunca sp. nov. Among these new records, four species were previously known from other Caribbean localities: Arturia vansoesti, Clathrina insularis, C. mutabilis, and Leucaltis clathria. Two species previously known in Brazilian waters are reported for the first time in the Caribbean Sea: Arturia alcatraziensis and C. cf. cylindractina. Finally, the occurrence of C. aurea and Leucetta floridana in Martinique is confirmed. The two molecular markers (ITS and C-LSU) and the morphological characters considered (e.g. body shape, aquiferous system and spicules) provided congruent classifications what tend to confirm their reliability for the taxonomy of Clathrinida. After the present work, a total of 17 species of Calcarea are recognised for Martinique. We discuss three types of distribution patterns (Endemic, Caribbean-Brazil, and Amphi-Atlantic), Martinique likely playing an important role as stepping stone to garantee connectivity among populations of Calcinea in the Atlantic.

Despite the acknowledged high diversity of sponges in the Caribbean Sea, calcareous sponges from this region have been poorly studied. In order to start filling this gap, in this study we describe the calcareous sponges from Curaçao, Southern Caribbean. The specimens were collected by SCUBA in eight localities along the island of Curaçao and analysed by morphological and molecular (ITS and C-LSU) approaches. A total of 16 species were found and are described here. Ten species are new to science and are provisionally endemic to Curaçao: Arturia vansoesti sp. nov., Clathrina curacaoensis sp. nov., Clathrina globulosa sp. nov., Grantessa tumida sp. nov., Leucandra caribea sp. nov., Leucilla antillana sp. nov., Leucilla micropilosa sp. nov., Leucandrilla quadriradiata sp. nov., Sycon conulosum sp. nov. and Sycon magnapicale sp. nov. The formerly Brazilian endemic species Borojevia tenuispinata, C. lutea, C. insularis and C. mutabilis have their distribution widened to the Caribbean Sea. Clathrina hondurensis and Leucetta floridana are new records for Curaçaoan waters. With these new records, the diversity of calcareous sponges from the Caribbean Sea reaches 33 species. Some issues on the phylogeny of Calcarea are also discussed.