Placospongia colombiensis, David-Colón & Zea & Marín-Casas, 2023

David-Colón, Jesús, Zea, Sven & Marín-Casas, Dairo, 2023, The Genus Placospongia (Demospongiae: Clionaida) From The Colombian Caribbean, Zootaxa 5244 (6), pp. 501-526 : 514-520

Placospongia colombiensis sp. nov.

( Figure 6 ; Tables 4 and 5 )

Material examined: holotype, INV POR1443 (Santa Marta). Paratype, Santa Marta, INV POR1444.

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Additional material. Bahamas, uncatalogued fragment 360. (See Table 4 for full specimen details.)

Type locality: Morrito , Bahía de Santa Marta, Colombia, 11°15’04.89”N, 74°13’21.84”W .

Diagnosis: megascleres tylostyles of two sizes. Microscleres selenasters, spherasters and streptasters as spirasters in two types distinguishable in size and shape, type I elongated with up to 4 turns with short rays, type II short with branching rays in rosettes.

External morphology: ( Figure 6A ) encrustation 15–20 cm in diameter. Surface of plates smooth, surrounded by contractile grooves that extend in different orientations and converge 2 to 3 at the oscules. Between grooves, pores and oscules are perforations of the dermis, not raised or surrounded by a semitransparent membrane.

Color: in life orange yellow or orange; whitish (alcohol).

Consistency: hard, stony; inner tissue compressible in vivo to some extent by pushing the plates.

Skeleton: ectosome up to 1 mm thick, constructed of a dense layer of selenasters, supported in the grooves by tracts of small tylostyles with tips upward. Choanosome thinner than the cortex (0.41 mm maximum), with free selenasters and spirasters. Scattered tracts of tylostyles up to 0.18 mm thick cross it. Choanosome base with a layer of selenasters up to 0.9 mm thick.

Spicules: ( Figures 6C‒J ) tylostyles, selenasters, spherasters and streptasters. Tylostyles I larger, with rounded heads and tips, 407– 689.9 –943 x 7 –14.9 –24 µm. Tylostyles II smaller, with sharp tips, 165– 258 –460 x 10– 14.2 –19 µm. Selenasters elliptical with an inward curvature on one side; the difference in diameter of the sides is clear, 42– 60.6 –84 x 25– 39.8 –49 µm. Spherasters round, usually with short rays, some with sharp tips resembling spheroxyasters, although these may be developmental forms, 11– 16.3 –22 µm. Streptasters as two types of spirasters, distinguishable in size and shape; spirasters I long, thin, straight or curved shafts, with up to 4 turns; rays are few and short, located at the top and the end of the turns, 11 –21.6 –39 µm; shaft diameter: 1 –3 –6 µm; spirasters II short, shaft with few rays, which are thick, small, and may be branched into small spines, resembling rosettes, especially at end of shafts, similar to those of Placospongia anthosigma ( Tanita and Hoshino 1989) , 3– 6.7 –11 µm, shaft diameter 1– 1.7 –3 µm (for measurements of spicules of all specimens see Table 5 ).

Ecology: found in rocky and coral sub-littoral, between cracks. One specimen had attached fish eggs ( Figure 6A ). Found: 1‒22 m deep.

Distribution: Colombia (Santa Marta) and The Bahamas.

Etymology: referring to the country of origin, Colombia.

Remarks: this new species is distinguished from other Placospongia by the absence of microrhabds and microspherasters, and the presence of two types of streptasters in the shape of spirasters, type I with a thin, elongated shaft, with short and few rays, and type II with a short shaft, with branched rays resembling rosettes. This may be one of the few species of Placospongia that can be identified in the field with some ease, since in the Central Western Atlantic it is the only one that presents a clear yellow to orange color, and its oscules are not raised in the form of a membranous cone.

Figures

FIGURE 6. Placospongia colombiensis sp. nov. A. Underwater photograph of the holotype INV POR1443 (approximate scale: 5 cm). B. Underwater photograph of the uncatalogued specimen 360 from The Bahamas (approximate scale: 3 cm). C. Tylostyle I (scale: 100 µm). D. Tylostyle I head and tip (scale: 20 µm). E. Tylostyle II (scale: 100 µm). F. Tylostyle II head and tip (scale: 20 µm). G. Selenaster (scale: 20 µm). H. Spheraster (scale: 10 µm). I. Spiraster I (scale: 20 µm). J. Spiraster II (scale: 5 µm).