Until now, 127 species of marine sponges have been recorded in the southern Gulf of Mexico (SGoM). In this study, we describe the sponge fauna recorded on 16 coral reefs of the SGoM, defined as the Mexican waters of the Gulf of Mexico (GoM), during a period from 2005 to 2019. We report 80 sponge species, including 34 first geographic records for the southern GoM region. The latter are fully described and illustrated, taking into account 24 that represent new records for the GoM: Agelas conifera, Agelas sventres, Agelas wiedenmayeri, Prosuberites carriebowensis, Desmanthus meandroides, Cliona aprica, Cliona dioryssa, Placospongia ruetzleri, Haliclona (Gellius) megasclera, Haliclona (Reniera) aff. portroyalensis, Neopetrosia proxima, Xestospongia arenosa, Calyx podatypa, Shiphonodictyon xamaycaense, Acarnus innominatus, Iotrochota arenosa, Polymastia tenax, Svenzea cristinae, Svenzea flava, Svenzea tubulosa, Svenzea zeai, Timea stenosclera, Stellettinopsis megastylifera, Suberea flavolivescens. The present work highlights the understimated and remarkable diversity of reef-associated sponges within the Campeche Bank Coral reef systems. Present work data was compiled with existing published information to produce an updated list of 161 known sponges in the southern GoM.

Marine sponges usually constitute the most diverse group of the benthic community in coral reefs. Although they are reasonably well studied at the northern Gulf of Mexico (GMx), the southern GMx is poorly known and lacks records from many major reef systems that lie off the Mexican coast. The present taxonomic study is the first sponge account from Alacranes reef, the largest coral reef system in the GMx, and from the shallow reef banks of Sisal, both in the northwest Yucatan Peninsula. The 19 species herein described represent the first sponge fauna records from these reefs. Among these, seven species represent new record for GMx: Erylus formosus, Cliona flavifodina, Spirastrella aff. mollis, Strongylacidon bermuda, Topsentia bahamensis, Agelas tubulata and Chelonaplysilla aff. erecta. Twelve species are new records for the Southern GMx: Erylus trisphaerus, Cliona amplicavata, Chondrilla caribensis, Halichondria lutea, Hymeniacidon caerulea, Axinella corrugata, Dragmacidon reticulatum, Chalinula molitba, Amphimedon caribica, A. complanata, Hyatella cavernosa and Dysidea variabilis. Additionally, a redescription of Erylus trisphaerus is presented which had not been reviewed since its original description in 1953 off Western Florida, except that it was listed for north La Habana, Cuba.

Autonomous reef monitoring structures (ARMS) have been proposed as a standardized, passive, nondestructive sampling tool. This study assessed the ability of ARMS to capture the cryptic species diversity of two coral reefs by recording species richness and taxonomic representativeness using conventional taxonomy. The capacity of ARMS, as artificial substrates, to favor the establishment of nonindigenous species over native species was also evaluated. The use of ARMS allowed the detection of 370 species morphotypes from nine phyla, yielding 13 new records of geographic distribution expansion, one exotic species for the Gulf of México and the Caribbean Sea, and six newly described species. It was also possible to make spatial comparisons of species richness between both reefs. ARMS captured cryptic diversity exceptionally well, with the exception of echinoderms. Furthermore, these artificial structures did not hinder the colonization ability of native species; in fact, the colonization patterns on the structures themselves represented the spatial differences in the structure of benthic assemblages. This study represents the first effort to make a conventional taxonomic description of the cryptic fauna of the Yucatan Peninsula using ARMS. It is recommended to assess coral reef species diversity, but more taxonomists specialized in marine invertebrates are needed.

Sponges and decapods share diverse ecological interactions, including epibiosis in which sponges colonize crab carapaces. We report three sponge species—Stelletta kallitetilla (Laubenfels, 1936), Hymeniacidon heliophila (Wilson, 1911), and Haliclona (Reniera) manglaris Alcolado, 1984—on the decorator crab Macrocoeloma nodipes (Desbonne in Desbonne & Schramm, 1867) collected from the Campeche Bank (southern Gulf of Mexico), presenting new records for Mexican waters. Our research highlights the importance of describing ecologically associated species and offers insights into the presence of sponge species not previously reported in Mexico.

This Infographic is a product of BDMY (https://www.bdmy.org.mx) project, that was produced with funds of the Harte Research Institute for Gulf of Mexico Studies, and CONABIO (Mexico). The information in the infographic was reviewed and validated by a group of specialists in the taxon.