An annotated and illustrated identification guide to common mesophotic reef sponges (Porifera, Demospongiae, Hexactinellida, and Homoscleromorpha) inhabiting Flower Garden Banks National Marine Sanctuary and vicinities Author Diaz, Maria Cristina https://orcid.org/0000-0001-9485-0011 Harbor Branch Oceanographic Institute, Florida Atlantic University, Fort Pierce, FL, USA taxochica@gmail.com Author Nuttall, Marissa https://orcid.org/0000-0003-1384-8978 Flower Garden Banks National Marine Sanctuary, Galveston, TX, USA & CPC Inc, Galveston, TX, USA Author Pomponi, Shirley A. https://orcid.org/0000-0003-4982-1515 Harbor Branch Oceanographic Institute, Florida Atlantic University, Fort Pierce, FL, USA Author Ruetzler, Klaus National Museum of Natural History, Smithsonian Institution, Washington D. C., USA Author Klontz, Sarah Genetic Disease Research Branch, NHGRI, NIH, Bethesda, MD, USA Author Adams, Christi https://orcid.org/0000-0002-8411-4595 Flower Garden Banks National Marine Sanctuary, Galveston, TX, USA Author Hickerson, Emma L. https://orcid.org/0000-0002-2595-8878 Flower Garden Banks National Marine Sanctuary, Galveston, TX, USA Author Schmahl, G. P. https://orcid.org/0000-0002-5657-5204 Flower Garden Banks National Marine Sanctuary, Galveston, TX, USA text ZooKeys 2023 2023-05-11 1161 1 68 http://dx.doi.org/10.3897/zookeys.1161.93754 journal article http://dx.doi.org/10.3897/zookeys.1161.93754 1313-2970-1161-1 4CE0D6C5C3044F748387FCC71F8F8AC0 97BBCF0865EA537F8147171EA5BBA1B5 Siphonodictyon sp. nov. 1 Fig. 28 Diagnostic features. Large massive sponge with abundant long yellow brown oscular tubes (3-12 cm long and 1.5-2 cm wide) that project between shorter, amorphous to digitate drab yellow fistules (1-4 cm high and <10 cm long). Only a soft and smooth oscular tube was collected and had only oxeas as spicules. 18S sequences (738 bp) show that this species is separated phylogenetically from a clade formed by sequences of Siphonodictyon coralliophagum and Siphonodictyon brevitubulatum available on GenBank (Diaz, Segura, and Pomponi, unpublished data). Figure 28. Siphonodictyon sp. nov. 1, 67 m deep. Sample GFOE3-2. Similar species. Oceanapia spp. may have similar oscular tubes and fistules ( Santos Neto et al. 2018 ). The genetic data was essential to provide the generic assignation to this species. Distribution and abundance. The species was seen once at Geyer Bank at FGBNMS. Ecology. Found in algal nodule beds. This species is a bio-eroding sponge. Identification. Iris Segura, KR, MCD. Reference. Ruetzler 1971; Ruetzler et al. 2014.