Aplysina encarnacionae, Gómez & González-Acosta & Sánchez-Ortíz & Hoffman & Hernández-Guerrero, 2018

Gómez, Patricia, González-Acosta, Bárbara, Sánchez-Ortíz, Carlos, Hoffman, Zvi & Hernández-Guerrero, Claudia J., 2018, Amended definitions for Aplysinidae and Aplysina (Porifera, Demospongiae, Verongiida): on three new species from a remarkable population in the Gulf of California, Zootaxa 4455 (2), pp. 322-342 : 327-330

Aplysina encarnacionae sp. nov.

( Figs. 3 , 4 )

Material examined. Holotype CNPGG‒1397 El Gallo, 24°27’54.76”N 110°23’14.75”W, 16/XII/2011, 5 m. Paratypes: USNM‒1283359 El Gallo, 24°27’54.76”N 110°23’14.75” W, 16/XII/2011. CNPGG‒353 Espiritu Santo Is., 25/VIII/1984. CNPGG‒1221, 1318, 1368, 1398 El Gallo, 24°27’54.76”N 110°23’14.75” W, 16/XII/2011, 2‒ 15 m. CNPGG‒1316, 1317, 1402 La Ballena Is. 24°28’56”N 110°23’59”W, 25/VIII/1984. CNPGG‒1400, 1401 El Gallo, 24°27’54.76”N 110°23’14.75”W, 10/VIII/2 0 12. CNPGG‒1408 El Gallo, 24°27’54.76”N 110°23’14.75”W, 8/IX/2012, 5.8 m.

Description. Tubular sponge, growing as a single tube 16 cm high by 5.5 cm in diameter, or in clusters of up to 12 tubes, laterally fused, the highest tube is 22 cm with 2‒2.5 cm in diameter. Tubes also grow over a massive body, with smaller tubes at the base of it, never with fistular projections. Its maximum growth range reaches 38 cm in height, 20 cm in width, tube diameter 2.0‒ 6.5 cm; smaller tubes are 7 mm high, 17 mm in diameter ( Fig. 3 A-B). The tube wall measures 8‒19 mm thick, topped by an apical pseudoscule 1 mm wide in the smallest tubes, up to 2.5 cm in the largest; a diaphragm is present in some, considerably contracted to almost closed when is out of the water. Each atrium may have several oscula (2 mm diameter), and these are also seen in the outer surface of the tube. The surface is microconulose in parts and smooth in others; the conules, <1 mm to up to 3.8 mm in height, are numerous on top of some tubes and scattered at their basal margin, separated by 0.6‒7.0 mm. The color when alive is reddish purple, sometimes with small yellow tinges; it is mustard yellow inside, entirely dark purple in alcohol. It is soft and compressible with a slippery texture whether alive or in alcohol. The dermis is easily detachable. The choanocyte chambers, 20‒30 µm in diameter, are diplodal and spherical.

Skeleton. This is a polygonal anastomosed reticulum lining the atrium wall from which long dendritic fibers fill out the tube wall or, sometimes according to the body part, a reduced tridimensional regular polygonal net is present, without neglecting the continuous set of dendritic fibers (0.5‒15 mm long) that fill out most part of the tube. The latter fibers very seldom anastomose in which case, may form an elongated and larger mesh, distinctively they are more dendritic near to the surface. Fibers are amber in color, stratified with light and dark brown pith. In the deep choanosome, they are thicker in diameter, 90‒270 µm, with a pith diameter 70‒140 µm respectively, they conform meshes 234‒3406 µm wide ( Fig. 4 ). Dendritic fibers possess round endings and sometimes frizzled, 23‒ 150 µm in diameter with 20‒110 µm pith diameter; they have relatively thicker pith with respect to fiber diameter.

Ecology. The new species is the largest Aplysina in the La Paz region, and is endemic to Espiritu Santo Island (i.e. La Gallina, El Gallo , and La Ballena locations). It occurs on rocky reef substratum (boulders, walls, and small caves), whether exposed or protected from light, inhabiting from 2‒15 m depths corresponding to 21 and 18°C temperature, it is common on shores sheltered against wave and wind action at Espiritu Santo Is. In this environment A. encarnacionae reaches its greatest growth form both in height, and overall size. The opistobranch mollusc Tylodina fungina Gabb, 1865 is a yellow Sulphur ( Aplysina ) sponge consumer (David W. Behrens), commonly found as a predator on this new species. Some Haliclona spp. and snapping shrimps were also associated.

Distribution. A. encarnacionae sp. nov. is recorded only at Espiritu Santo Is. (La Gallina, El Gallo , and La Ballena Islands), in La Paz Bay (Baja California Sur, Mexico), in shallow waters on sheltered shores. This unusual species has not been collected in the many locations studied along the eastern Pacific, nor reported in any other published paper. Hence, its endemism to the area is clear. A different morphotype or more probably a juvenile stage of the present species could be a smaller tube 10 cm long, by 1.5 cm in diameter, with morphologic diagnostic characters, skeletal and fibers similar to A. encarnacionae sp. nov. Not included within the examined material owing to the lack of molecular study to assign the species.

Etymology. The specific name encarnacionae is dedicated to Dr. Rosalba Encarnación Dimayuga, formerly professor at the Universidad Autónoma de Baja California Sur. Her perseverance and enthusiasm led to the identification of several sponge samples of the eastern Pacific. She collected some type specimens of verongiids in 1984 for biochemical studies; her samples are included in the present study, having stayed undetermined until now.

Remarks. All previously described species of Aplysina from the Pacific have different shapes when compared to Aplysina encarnacionae sp. nov. (tubular), and additionally, possess only anastomosed skeletons only, lacking the component of dendritic fibers seen in the new species. Those species include A. gerardogreeni , encrusting with small lobes on top; A. chiriquiensis , ramose; A. clathrata , massive-sprawling, clathrate; and A. revillagigedi , massive-sprawling. Suberea azteca possesses a similar skeletal arrangement, anastomosed with long dendritic fibers in addition. This species will be commented upon below. The species appearing closest to A. encarnacionae is A. airapii sp. nov., which will be described below, where both species will be compared.

Supposedly, the Caribbean Aplysina fistularis , a tubular sponge, was reported at the eastern Pacific by Bakus & Abbot (1980) and Sim & Bakus (1986), the two forms from California ( USA). Nevertheless, the former authors describe it very briefly as an encrusting species, highlighting a reticulate skeleton with no skeletal measurements, and assigning Aiolochroia thiona (as Verongia t.), and Smenospongia aurea (as Verongia a.) to its synonymy. Sim & Bakus (1986), on the other hand, quoted a hollow cylinder indeed, but its fiber diameters are too thin 45‒106 µm compared with the new species described herein, as well as their mesh size 28‒80 µm. Nowise these data belong to a genuine Caribbean A. fistularis , even less to the present new species. A. fistularis reported from Rocas Alijos ( Austin 1996), and another from Partida Island (BCS, Betancourt-Lozano et. al. 1998), and those in field invertebrate guides ( Kerstitch 1989; Gotshall 1998; Kerstitch & Bertsch 2007) are unjustified as well. All these records refer to massively-sprawling specimens, varying from flat, coarse mats, to irregular, fingerlike projections, living under rock ledges or not, with no measurements given.

Aplysina fistularis from the Caribbean is a tubular sponge comparable to the present new species. However, these two species differ in several significant traits including even their tubular habit. A. encarnacionae sp. nov. has an irregularly and thinly conulose surface, with slippery smooth areas, whereas A. fistularis is homogeneously conulose, has a rough texture, and sometimes bears coarse ridges and folds, besides being yellow or brown in life ( Pinheiro et al. 2007, Hajdu et al. 2011). The consistency is leathery in A. encarnacionae sp. nov. and soft or hard in A. fistularis . Other traits vary also, but above all the skeletal structure in A. fistularis is a much more regular anastomosed network. No dendritic fibers are present except those at the conule tips, and fiber diameters are much thinner 30‒280 µm with respect to the new species, with pith diameter also thinner 10‒60 µm ( Pinheiro et al. 2007; Hajdu et al. 2011). All these features differ from those observed in A. encarnacionae sp. nov. (see above).

Molecular data (ITS region) confirmed A. encarnacionae sp. nov. ’s nesting in Aplysina ; in a subclade of Eastern Tropical Pacific species, separated by a wide gap from species at a Caribbean clade, which prompted us to distinguish it as a new species.

Figures

FIGURE 3. A‒B. Aplysina encarnacionae sp. nov., C‒D. Aplysina airapii sp. nov. at Espiritu Santo Island, BCS, Mexico. Underwater photographs in vivo.

FIGURE 4. Aplysina encarnacionae sp. nov., A. General structure of the skeletal architecture, atrium fibers at the bottom. B. Isolated dendritic fiber. C. Polygonal anastomosed fibers of atrium. D. Detail of dendritic fibers, E. Detail of anastomosed fiber.