Clathria (Thalysias) opalina Zea, Rodríguez & Martínez, 2014, new species

Clathria (Thalysias) opalina new species

Fig 16, 17, plate 3, figures C, D, E, F

? Poecilosclerida sp. 3; Zea 1993: 88 (ecology). Poecilosclerida sp. 3; Zea 1994b: 261 (ecology).

Material examined. Santa Marta: Holotype: ICN-MHN(Po) 265, Canal de La Aguja, on exposed littoral rock, 5 m, coll. S. Zea, 28 Apr. 1982. Paratypes, INV-POR 1241 (20 m, 26 Apr. 1983), INV-POR 1242 (15 m, 3 Oct. 1983), Bahía de Santa Marta, Punta de Betín, on dead coral, reef, coll. S. Zea; INV-POR 1243 (reef slope, 23–24 m, 18–19 Apr. 1988), 1244 (reef base, 34–35 m, 10–12 Feb. 1988); INV-POR 1245 (overhanging littoral rock, 9 m, 18 Feb. 1994), INV-POR 1246 (overhanging littoral rock, 4.5 m, 11 Dec. 1993), INV-POR 1247 (exposed littoral rock, 8 m, 18 Jan. 1994), Bahía de Santa Marta, El Morro, on crustose coralline algae, coll. S. Zea.

Shape, color and consistency. Thin encrustations, covering several square centimeters, usually irregular in outline; frequently, small (1–2 cm in diameter) individuals or fragments are seen in groups, completely surrounded by other encrusting sponges. Ectosome transparent, cellophane-like in aspect; when live slightly elevated (inflated?) over extensive subdermal spaces, which make the sponge looks thicker that the neighboring substrata; oscules 500 µm– 2 mm in diameter, spaced every 8–12 mm, with a slightly elevated collar; the vein pattern of the canal system is somewhat obscured by the elevated ectosome; some areas around oscules have pore fields, each pore aproximatelly 120 µm in diameter. In illuminated sites the ectosome is creamy and transparent, with the choanosomal tissues underneath having various shades of orange to yellowish, to brownish. Specimens in shallow overhangs or deep areas have an iridescent ectosome with whitish oscules, and the flesh underneath is light brownish. The consistency of the ectosome is characteristically slightly leathery, easily detachable but difficult to tear; choanosome soft.

Skeleton. Ectosome is a pliable pinacoderm supported in some areas by brushes of small auxiliary subtylostyles; other areas with paratangential, plumose tracts of large to small auxiliary subtylostyles; yet other areas (probably those above extensive subdermal spaces) without support, with just a few, tangentially placed subtylostyles. Choanosome with numerous accessory acanthostyles erect on the substratum, usually partly embedded in crustose coralline algal tissue. Basal principal styles usually solitary but sometimes in groups, are spaced every 140–200 µm, and placed erect and with heads against the substratum, embedded in a thin knob of spongin. From their medial part, brushes of large subectosomal auxiliary subtylostyle support the small, ectosomal brushes in thin areas of the body; thicker areas may have thick tracts of large subtylostyles, sometimes anastomosing, which end in the ectosomal brushes. Spicules (Table 1): (1) basal principal styles, long, slightly curved, with heads slightly to strongly spined, and ends short, telescopic, sometimes blunt, 219– 356.3 –584 µm by 5.7– 10.9 –14.3; these may be scarce and thin in some specimens. (2) Straight auxiliary subtylostyles, with small, smooth heads, and with telescopic, usually blunt to almost strongylote ends; axial canal wide and visible; there is a clear separation in two size categories: long, choanosomal to subectosomal to paratangential ones, 286– 368.1 –418 µm by 2.4– 5.7 –8.6 µm, and smaller, ectosomal ones, 152– 200.0 –261 µm by 2.4– 3.3 –4.8 µm; developmental stages are rhaphidiform. (3) Basal accessory acanthostyles, with a prominent head, heavily spined; the basal and apical third with fewer or no spines, 90– 112.1 –128 µm by 3.8– 5.2 –7.6 µm. (4) Palmate chelae, 12.7–20.7 µm, usually in two, slightly different shapes, one with a sharply bent contour and the other more roundish (although this may be an artifact of their orientation in the sample).

Type locality. Canal de la Aguja, between Punta Aguja and Isla Aguja, Santa Marta area, Colombia, Caribbean Sea (11° 18' 28" N; 74° 11' 32" W).

Distribution and ecology. Santa Marta, Colombia. It inhabits rocky shores and coral reefs, from 4–5 to 36 m; usually quite abundant in the deeper reef areas near the city of Santa Marta, up to 2.1 % cover in transects at 17–22 m depth (Zea 1994b).

Etymology. Adjective derived from Latin opalus and Greek opallius for opal, a precious stone showing interplay of soft milky colors.

Remarks. At first, the identity of this species was unclear (e.g., Zea 1993, 1994b), but detailed study of the spicules and architecture of the skeleton led to its placement in Clathria (Thalysias). It is readily distinguished from other encrusting Clathria by its cellophane-like pliable pinacoderm. It may perhaps be confused in the field with C. venosa, but it lacks the well-developed vein pattern of the canal system. C. opalina shares with co-existing species C. (T.) sulfocleistochela n. sp. and C. (T.) chelosigmoidea n. sp., the consistent lack of toxa in all specimens examined. Besides these three species, few Clathria from the Greater Caribbean appear to lack toxa (either normal or rhaphidiform to oxeote). C. (Clathria) vasiformis (de Laubenfels, 1953), C. (C.) foliacea Topsent, 1889 and C. (C.) carteri Topsent, 1889 were originally described as lacking toxa (see also van Soest 1984), but the latter two were found to possess them, although sometimes rare or absent (Gómez 2014). C. vasiformis is vase shaped and lacks microscleres altogether; its generic assignment needs to be reassessed (e.g., Wiedenmayer 1977). When contrasted to specimens of other Greater Caribbean species that may lack toxa, the distinguishing characteristics of its spicules are the slender principal styles with rugose heads, the somewhat large accessory acanthostyles, and the secondary subtylostyles having blunt ends and a visible axial canal. The iridescent color of this species in dark and deep sites is remarkable, similar to that of Caribbean tube sponge Callyspongia plicifera (see Zea et al. 2009).

PLATE 1. Underwater photographs of Clathria (Thalysias) species described in this work. (A–B): Clathria (Thalysias) virgultosa, (A) encrusting specimen from Santa Marta, 4 m depth, (B) branching specimen from Old Providence, 20 m depth. (C–E): Clathria (Thalysias) curacaoensis, (C) encrusting specimen from Santa Marta, 4.5 m depth, (D) branching specimen from Islas del Rosario, on seagrass bed, 1 m depth, (E) encrusting and branching specimen from mangrove stilt roots, Santa Marta, 0.3 m. (F–G): Clathria (Thalysias) venosa, encrusting specimens from Santa Marta, about 15 m depth.

PLATE 2. Underwater photographs of Clathria (Thalysias) species described in this work. (A–B): Clathria (Thalysias) minuta, encrusting specimens from Santa Marta, 8–9 m depth. (C–D): Clathria (Thalysias) oxeota, encrusting specimens from Bocas del Toro, Panama, 6–12 m depth. (E–F): Clathria (Thalysias) sulfocleistochela n. sp., encrusting specimens from Santa Marta, (E) 20 m [lower right specimen is C. (T.) venosa], (F) 9 m. For scale in D to F, see the caliper cm (left) and inches (right) markings.

PLATE 3. Underwater photographs of Clathria (Thalysias) species described in this work. (A–B): Clathria (Thalysias) chelosigmoidea n. sp., encrusting specimens from Santa Marta, 7–9 m depth. (C–F): Clathria (Thalysias) opalina n. sp., encrusting specimens from Santa Marta, 15–20 m depth. Upper right specimen in D is C. (T.) sulfocleistochela. Notice a noniridiscent specimen in E. The cinnamon sponge that surrounds iridescent spots of C. (T.) opalina in F is an unidentified Poecilosclerid. For scale in A and C, see the caliper cm (left) and inches (right) markings.