Placospongia caribica, Rützler, Klaus, Piantoni, Carla, Van, Rob W. M. & Díaz, Cristina, 2014

Rützler, Klaus, Piantoni, Carla, Van, Rob W. M. & Díaz, Cristina, 2014, Diversity of sponges (Porifera) from cryptic habitats on the Belize barrier reef near Carrie Bow Cay, Zootaxa 3805 (1), pp. 1-129 : 34-36

Placospongia caribica new species

( Figures 3 c, 18)

Synonymy. Placospongia carinata Bowerbank, 1858 : Macintyre et al. (1982): 134, fig. 82a.

Material. Holotype: USNM 32873 Columbus Cay cave, 23 m; G. Hendler, I. Macintyre, P. Kier, T. Rath and C. Clark col. 21 Mar 1979.

Paratype: USNM 1228945, Columbus Cay cave, 20 m; I. G. Macintyre and G. Hendler col. 26 Apr 1979.

Additional material examined: USNM 22201, Placospongia intermedia Sollas , Panama City, Panama (Pacific coast), intertidal rock and coral; de Laubenfels col. 23 July 1933. USNM 22233, Placospongia intermedia Sollas, Ft. Randolf , Panama (Atlantic coast), intertidal rock and coral; de Laubenfels col. 28 Jul 1933. USNM 33178, Carrie Bow Cay East lagoon, 1 m; R. Larson col. 19 Apr 1972.

Diagnosis. Placospongia with two categories tylostyles, small (<60 µm average) selenasters, spherasters, spirasters (some approaching amphiasters), oxyasters, and spiny microrhabds.

External morphology. Encrusting clusters of deserted serpulid polychaete tubes (“pseudostalactites”), up to 50 cm 2 area, 1–5 mm thick. Surface composed of polygonal cortical plates, defined by and surrounded by pore grooves (when specimens are alive and active), a characteristic of the family. Fully open pore grooves can be as much as 4 mm wide. Consistency is hard, due to the cortex, color is ochre to deep orange brown.

Skeleton structure. Ectosomal cortex plates are made up by selenasters, cemented together and accompanied by a small category of tylostyles and by small amphiasters, spirasters, oxyasters, and spiny microrhabds. The plates are supported along their edges by tracts of large-category tylostyles that rise from the substratum, points outward. Small tylostyles and more microscleres are dispersed throughout the choanosome.

Spicules. Tylostyles in two size classes, many with pronounced tyles and rounded points, but also (among the larger class) with subterminal tyles or with styloid and even strongylote modifications; tylostyles I: 480–870 x 10–15 (641 x 14) Μm; tylostyles II: 182–440 x 8–11 (275 x 9) Μm; selenasters, ovoid to bean-shaped (disregarding developmental stages showing free spines): 53–70 x 30–58 (59 x 43) Μm; spherasters with large centers (90% of total diameter): 10–28 (18) µm; spirasters, with twisted shaft (1–3 turns), rays of equal length or up to double the diameter of the shaft, some approaching amphiasters by having spines concentrated at the ends of shafts; most are more or less microspined: 13– 35 x 6–13 (26 x 11) Μm; oxyasters, with small center and about six microspined rays: 10–18 (13) µm; spiny microrhabds, with straight or slightly bent axis densely beset by short, simple spines or clusters of thick, microspined rays: 5– 15 x 1–9 (9 x 6) Μm.

Ecology. Inhabits the dark ceiling of a lagoonal karst cave, 10–15 m from the sinkhole entrance, 20–23 m depth.

Distribution. Belize.

Etymology. Named after the Caribbean Sea, locality of its discovery.

Comments. Due to the diligent analyses by van Soest (2009) and Becking (2013) we have excellent information about type material and synonymies of Placospongia species. Five species are known that include among their microscleres spherasters with short, broad-based spines, about 20 Μm in diameter, termed “golf balls” by van Soest (2009). These spherasters co-occur (in addition to the always present selenasters) with short, stout, spirasters (“anthosigmas”) in P. an t ho s i g m a (Tanita & Hoshino, 1989; as Geodinella ), with minute (ca. 2 Μm), microspined spherules in P. melobesioides Gray, 1867 (the genotype), or with long-rayed streptasters and microacanthose microrhabds in P. m i x t a Thiele, 1900 (SEM images in Becking, 2013); in addition, they occur without other (non-selenastrose) microscleres in P. cristata Boury-Esnault, 1973 , and with smooth or microspined microstrongyles (with some transitions to spirasters) in P. intermedia Sollas, 1888 . All these species containing spherasters are from the Indo-Pacific or (the latter species) the eastern Pacific, except for P. cristata , which was first reported from off Recife, Brazil. P. intermedia , originally collected at the Pacific coast of Costa Rica (“Punta Arenas, Central America ”), was subsequently described from both the Pacific and Atlantic sides of Panama (de Laubenfels, 1936a). These records were since considered doubtful (van Soest, 2009), mainly because de Laubenfels’ measurements of selenasters and spherasters were considerably smaller than those listed by the original describer (Sollas, 1888). However, we re-measured spicules on de Laubenfels’ original slide preparations and found selenaster means of 66 x 52 µm, spheraster means of 20 µm, agreeing closely with Sollas’ 64 x 58 µm (selenasters) and 20 µm (spherasters); we could also confirm that there are no significant differences between the specimen on the Pacific (USNM 22201) and the one on the Atlantic side of the Panama isthmus (USNM 22233).

Our material of Placospongia caribica has characteristics closest to those of P. intermedia , but is distinguished by orange-brown (as opposed to chocolate brown) live color, larger tylostyles, larger and abundant spirasters, and presence of oxyasters. Spirasters (amphiasters) in our species are in a (larger) size category, distinct from the astrose derivatives of the microstrongyles in P. intermedia . We also compared it with a non-cryptic specimen of Placospongia collected in the barrier-reef lagoon close to Carrie Bow Cay (USNM 33178), which turned out to have spherasters as well but lacked spirasters and related spicule forms and could therefore be assigned to P. cristata .

Figures

FIGURE 3. In-situ photographs of new sponge species reported in this contribution (measurements in parentheses are picture widths): a, Tetralophophora mesoamericana (3 cm); b, Geodia cribrata (12 cm); c, Placospongia caribica on “ pseudostalactite ” made up by calcareous serpulid tubes (5 cm); d, Prosuberites carriebowensis (adjacent to Monanchora arbuscula to the lower right) (4 cm); e, Timea diplasterina (8 cm); f, Timea oxyasterina (4 cm); g, Rhaphidhistia belizensis (14 cm).