Bellactis lux n. sp. (Cnidaria: Anthozoa: Actiniaria: Aiptasiidae), a new sea anemone from the Gulf of Mexico Author Delgado, Alonso 0000-0001-7874-0293 Department of Evolution, Ecology & Organismal Biology, The Ohio State University, Columbus Ohio USA 43210 delgado. 152 @ osu. edu; https: // orcid. org / 0000 - 0001 - 7874 - 0293 delgado.152@osu.edu Author Larson, Paul 0000-0002-4698-3124 Florida Fish and Wildlife Conservation Commission, 100 8 Avenue SE, St. Petersburg, FL 33701, USA paul. larson @ myfwc. com; https: // orcid. org / 0000 - 0002 - 4698 - 3124 paul.larson@myfwc.com Author Sheridan, Nancy 0000-0002-4698-3124 Florida Fish and Wildlife Conservation Commission, 100 8 Avenue SE, St. Petersburg, FL 33701, USA paul. larson @ myfwc. com; https: // orcid. org / 0000 - 0002 - 4698 - 3124 paul.larson@myfwc.com Author Daly, Marymegan 0000-0001-7874-0293 Department of Evolution, Ecology & Organismal Biology, The Ohio State University, Columbus Ohio USA 43210 delgado. 152 @ osu. edu; https: // orcid. org / 0000 - 0001 - 7874 - 0293 delgado.152@osu.edu text Zootaxa 2023 2023-10-11 5353 4 379 392 http://dx.doi.org/10.11646/zootaxa.5353.4.5 journal article 10.11646/zootaxa.5353.4.5 1175-5326 C76FDD6A-9810-4A5D-99C9-FE8F22C635DF Genus Bellactis Dube, 1983 Diagnosis: (after Dube, 1983 with changes in bold) Aiptasiidae with broad base. Column smooth, thin, with 2–4 rows of cinclides in mid-column; distinction between scapus and capitulum generally distinguishable in living specimens. Mesogleal marginal sphincter weak, alveolar, may be absent in small individuals . Oral disc lobed. Tentacles very numerous, stout. More mesenteries proximally than distally. Mesenteries irregularly arranged; six or seven pairs of perfect mesenteries; first and second cycles fertile. Retractor muscles broad but restricted. Acontia numerous. Asexual reproduction via longitudinal fission and pedal laceration occurs in at least some members. Hosts Symbiodinaceae spp. in gastrodermis. Cnidom: spirocysts (tentacles), basitrichs (pedal disc, column, tentacles, actinopharynx, filaments, acontia), and microbasic b-mastigophores (column) and microbasic p-amastigophores (pedal disc, tentacles, actinopharynx, filaments, acontia). FIGURE 1. External anatomy of specimen Bellactis lux , n. sp. A. Top view of living animal, showing oral disc and mouth. B. Side view of living animal, showing tentacles, column, and limbus. Pedal disc is retracted into the proximal column. C. Lateral view of living animal, showing raised cinclides in mid-column. Tentacles inflated and pointed inwards. The scale bar is 5mm. D. Lateral view of preserved animal, showing outer tentacles forming bunches in the endo- and exo- coels of last cycles of two short tentacles flanking a longer middle tentacle. Scale bar is 10mm. Explanation of changes: The diagnosis above incorporates information from previous descriptions and revisions ( Grajales and Rodríguez 2014 ; Ocaña et al. 2015 ) and information from the species described here. Per these additional records, we note that the base of many specimens is regular and oval, rather than irregular as described by Dube (1983) , although this feature varies among specimens and depends on the state of contraction. Likewise, the column is variable in height, from squat to elongate, depending on contraction. Whether the column is divided into a capitulum and scapus is not known for B. caeruleus , but in B. ilkalyseae and B. lux , this distinction is visible in living specimens (see Discussion). Tentacles are stout and may appear short relative to the column when the animal is extended. Retractor muscles restricted to diffuse: Grajales and Rodriguez (2014 : Fig. 18A) show sections through the type species B. ilkalyseae that are wide but restricted, and we see the same morphology in the new species described here and in B. caeruleus . Asexual reproduction via longitudinal fission has been documented in B. ilkalyseae (see OLIVEIRA and Gomes 2005 ) and pedal laceration is reported for B. caeruleus (see Ocaña et al. 2015 ), so Dube’s (1983) statement that they are not capable of asexual reproduction is incorrect and has been corrected in the genus diagnosis. Previous accounts of B. ilkalyseae and B. caeruleus describing irregularly-placed tentacles may be attributable to asexual reproduction, as might the variation in the shape of the pedal disc. We have amended the identity of the photosymbionts to reflect contemporary taxonomy of that lineage.