The Sponges of the Carmel Pinnacles Marine Protected Area Author Turner, Thomas L. Ecology, Evolution, and Marine Biology Department, University of California, Santa Barbara. Author Lonhart, Steve I. 0000-0002-5559-792X Monterey Bay National Marine Sanctuary, National Ocean Service, NOAA, Santa Cruz, California, USA. steve. lonhart @ noaa. gov; https: // orcid. org / 0000 - 0002 - 5559 - 792 X steve.lonhart@noaa.gov text Zootaxa 2023 2023-07-19 5318 2 151 194 http://dx.doi.org/10.11646/zootaxa.5318.2.1 journal article 56269 10.11646/zootaxa.5318.2.1 85d55564-632a-4561-8028-a7a8cf3f5de7 1175-5326 8162357 88714F9C-0EE5-4295-9988-3CEEF242489D Megaciella sanctuarium sp. nov. Figures 2 , 3 , 12 Material examined. Holotype : CASIZ236658 / IZC00048457 , Inner Carmel Pinnacle, ( 36.55852 , -121.96820 ), 10–24 m , 9/22/21. Etymology. Named in honor of Monterey Bay National Marine Sanctuary. Morphology. Thickly encrusting; sample is 3 cm thick, sponge was approximately 5–8 cm thick when entire. Vivid orange when alive, fades to beige in ethanol. Lumpy and irregular, with oscules occurring in approximate lines across the top of the sponge. Skeleton. Ascending paucispicular tracts of spongin cored with large styles, echinated by small acanthostyles, and accompanied by bundles of thin subtylotes. A chaotic paucispicular reticulation of large styles encased in spongin connects primary tracts. Ectosome a dense mass of thin strongyles/subtylotes, tangential and upright at all angles. Chelae present throughout but most dense at ectosome. Spicules. Large acanthostyles, acanthostrongyles, small acanthostyles, ectosomal strongyles/subtylotes, palmate isochelae, toxas. FIGURE 12 . Megaciella sanctuarium . A: field photo. B–C: cross sections showing choanosomal skeleton, with ectosomal skeleton visible in B. D: Large acanthostyle and acanthostrongyle. E. small acanthostyle. F: ectosomal strongyle. G: chela. H: Toxa. All images of holotype. Large acanthostyles: small spines concentrated at head, with a few on shaft. 180–302–382 x 8–20–26 μm (n=25). Acanthostrongyles: small spines concentrated at each end, with a few on shaft. Some are symmetrical, while others taper slightly towards one end. Appear to be modified large acanthostyles, but slightly shorter. Less common than large acanthostyles. 181–230–289 x 20–25–31 μm (n=9). Small acanthostyles: large spines, most dense on head but also covering shaft, head spines curve towards shaft and shaft spines curve towards head. 87–101–116 x 7–9–11 μm (n=22). Ectosomal strongyles/subtylotes: thin, straight rods with microspined ends; ends variably non–swollen (strongyles) or slightly swollen (subtylotes). 113–204–252 x 3–6–8 μm (n=20). Palmate isochelae: 17–20–22 μm (n=31). Toxas: 35–105–168 μm (n=24). Distribution and habitat. Only sample found to date was from the Carmel Pinnacles. Remarks. This species is in the Acarnidae , rather than the Microcionidae , because it possesses ectosomal tylotes rather than styles ( Hooper 2002a ). The choanosomal skeleton of ascending paucispicular fibers connected by a chaotic unispicular reticulation is consistent with the genus Megaciella . Of the 17 named species of Megaciella , 10 occur in the Northeast Pacific: 2 in Mexican waters and 10 from the Aleutians and/or the Russian Pacific. Only one of these, M. microtoxa ( Dickinson, 1945 ) has acanthostyles. This species, from the Gulf of California , is differentiated from the new species by having much larger coring styles and smaller chelae. There are also two undescribed species of Megaciella from California mentioned by Lee et al. (2007) . Both species have acanthostyles, but the spicule dimensions reported for these undescribed samples make them unlikely to be additional samples of Megaciella sanctuarium . Genetic data are unable to support or refute the morphological placement of this species. Both loci support a close relationship to the Microcionidae , though with inconsistent placement between the two loci (figures 2 & 3). No other species of Megacialla have data available for comparison, and the few other Acarnidae in the phylogenies are inconsistently placed. This species cannot be identified in the field due to multiple species of sympatric, thickly encrusting orange sponges in the Microcionidae .