Amended definitions for Aplysinidae and Aplysina (Porifera, Demospongiae, Verongiida): on three new species from a remarkable population in the Gulf of California Author Gómez, Patricia Author González-Acosta, Bárbara Author Sánchez-Ortíz, Carlos Author Hoffman, Zvi Author Hernández-Guerrero, Claudia J. text Zootaxa 2018 2018-08-02 4455 2 322 342 journal article 29104 10.11646/zootaxa.4455.2.4 fe0e811b-255d-4a15-859b-aec861ff4a84 1175-5326 1457256 82EA0ECB-4E33-4E22-99C1-98364576580A Aplysina sinuscaliforniensis sp. nov. ( Figs. 6 , 7 ) Material examined . Holotype CNPGG‒1338 El Gallo 24°27’54.76”N 110°23’14.75”W, 16/XII/2011 , 7 m. Paratypes: USNM‒1283361 El Gallo, 24°27’54.76”N 110°23’14.75”W, 16/XII/2011 , 5‒ 10 m . CNPGG‒1291, 1399 El Gallo 24°27’54.76”N 110°23’14.75”W, 16/XII/2011 , 5‒ 10 m . CNPGG‒1469 Calerita 24°21’12.06”N 110°17’0.56”W, 23/VIII/2011 , 3 m. CNPGG‒1471 El Candelero Islet 24°30’17.90”N 110°23’23”W, 2/XI/2014 , 4‒ 5 m . Description . This is a massive sponge, with low tubular processes, each topped by an apical pseudoscule. It may have 10‒19 low tubes, which are thicker than taller. Usually tubes grow one over the other from a common base. Tubes measure 2.5‒6 cm in diameter, 2.5‒8 cm in height, pseudoscule 0.6‒2 cm ( Fig. 6 ). The entire body is 11‒17 cm high and 8.5‒15 cm in diameter. The color in vivo is reddish brown or yellow with purple tinges outside, totally yellow inside, and dark purple in alcohol. It is slightly compressible in consistency, cheese-like. The regularly conulose surface has conules < 1 mm high, 1‒2 mm apart. Spherical embryos were observed (160‒220 µm) in a specimen during winter. Skeleton . This is an entirely cross-linked reticulation of evenly shaped fibers, with no distinction between primaries or secondaries nor dendritic fibers. Fibers are stratified, dark amber in color or maroon, 60‒170 µm diameter, with pith diameter 45‒80 µm, thicker near the surface. Polygonal meshes delineate apertures that are irregular or rounded, and 208‒2000 µm wide ( Fig. 7 ). FIGURE 6 . A‒B. Aplysina sinuscaliforniensis sp. nov. at Espiritu Santo Island, BCS, Mexico. Underwater photographs in vivo . Ecology . A. sinuscaliforniensis is the second most abundant Aplysina species in the La Paz region after A. clathrata ( Ulate et al. 2016 ) . It occurs on rocky reefs (boulders, walls, and small caves) from intertidal zones to 7 m depth, on both exposed and sheltered shores. Distribution . Aplysina sinuscaliforniensis sp. nov. is a common species around Espiritu Santo Island and along the shore of La Paz (Calerita, Baja California Sur , Mexico ). Etymology . The name sinuscaliforniensis refers to the occurrence of the species in the southern region of the Gulf of California, mainly at La Paz Bay. Remarks . Aplysina sinuscaliforniensis sp. nov. conforms to the typical Aplysina , distinguished by its massive shape with low and thick tubes, and entirely anastomosed skeleton. Some forms do resemble A. airapii sp. nov. (described above) on external morphology, although these two species differ consistently in skeletal arrangement, anastomosed/dendritic in A. airapii sp. nov. and entirely anastomosed in A. sinuscaliforniensis sp. nov. Three species of Aplysina of the eastern Pacific region regarded as having only anastomosed skeletons were compared with A. sinuscaliforniensis sp. nov. However, their morphology and likewise the anastomosed skeleton differ. A. gerardogreeni is a typical massive sprawling species with small tubes that do not exceed 3.8 cm in height. Specimens of the latter can extend to 1 m 2, and their skeletal fibers measure 30‒150 µm in diameter, with an average mesh size of 495 µm; slightly smaller than those in A. sinuscaliforniensis sp.nov. A differently shaped Aplysina is A. chiriquiensis whose habit is a pedunculated cluster of branches; its fibers 30‒210 µm in diameter, and mesh size of 200‒1200 µm; also smaller than those of A. sinuscaliforniensis sp. nov. A. clathrata is a cushionshaped, clathrate sponge, with oscules surrounded by a diaphragm-like membrane that collapses upon removal from the water, giving it a reticulate appearance; its anastomosed skeleton has fibers 50‒100 µm in diameter, and mesh size 0.6‒1 mm wide; that are less than half the size of those in A. sinuscaliforniensis sp. nov. In any case, the anastomosed skeletons differ sufficiently to support our proposition that both species are distinct.