Stryphnus raratriaenus, Cárdenas, Paco, Menegola, Carla, Rapp, Hans Tore & Díaz, Maria Cristina, 2009

Cárdenas, Paco, Menegola, Carla, Rapp, Hans Tore & Díaz, Maria Cristina, 2009, Morphological description and DNA barcodes of shallow-water Tetractinellida (Porifera: Demospongiae) from Bocas del Toro, Panama, with description of a new species, Zootaxa 2276, pp. 1-39 : 22-25

Stryphnus raratriaenus sp. nov.

( Figures 11–12 )

Material. ZMBN 81642, holotype, STRI Point (9°21’05’’N, 82°15’34’’W), Isla Colón, under coral rubble, 1 m depth. Fixed in ethanol 96%. Collected by M. C. Díaz, 18th August 2007, specimen has been cut in pieces for transport.

Additional material examined. Stryphnus ponderosus ( Bowerbank, 1866) , MC 3395, Rathlin Island, Northern Ireland. Stryphnus fortis ( Vosmaer, 1885) , ZMBN 82977, Korsfjord, Bergen region, Norway, 200– 400 m. Stryphnus mucronatus ( Schmidt, 1868) , MNHN Coll. Chombard, Mediterranean Sea, La Ciotat, France. Asteropus niger Hajdu & van Soest, 1992, ZMAPOR 14182, Curaçao, 39.5 m.

Outer morphology ( Fig. 11 A). Thickly encrusting sponge, 4 x 3 cm. Color alive is dark–brown with a whitish choanosome. In alcohol, these colors are preserved. No visible openings. Consistency is firm, choanosome is dense. Surface is rugose and flat.

Skeleton ( Fig. 11 B–C). Sanidasters and oxyasters are abundant in the thin cortex. Underneath, abundant paratangantial large oxeas fill the choanosome. Sanidasters and oxyasters are also abundant in the choanosome. A total of three dichotriaenes were found, two were observed in the thick sections, both perpendicular to the external layer, one with its cladome at the surface of the sponge, the other in the choanosome ( Fig. 11 C). Large brown granular cells (diameter: 14–23 µm) are observed mainly in the cortex but are also present in lower density in the choanosome.

Spicules ( Figs. 11 D–F, 12). Megascleres: (a) oxeas I ( Fig. 11 B), stout, straight or slightly bent, length: 1742– 1971 –2210 µm; width: 45– 62 –80 µm. (b) oxeas II, straight or slightly bent, length: 310– 448 –560 µm; width: 15– 22.2 –30 µm. (c) styles, length: 590– 603 –620 µm; width: 17.3– 18 –18.6 µm. (c) dichotriaenes, very rare, rhabdome with a strongyle end, deuteroclads can be further subdivided, rhabdome length: 447–620 µm (N=2); rhabdome width: 33–44 µm (N=2); protoclad length: 67–113 µm (N=2); deuteroclad length: 77–87 µm (N=2). Microscleres: (d) sanidasters ( Fig. 11 D), spiny, length: 16– 20.2 –23.9 µm; width (axis and actines included): 2.1– 2.9 –4 µm. (h) oxyasters ( Fig. 11 E–F), 5–8 actines, faintly spiny, diameter: 29.3– 33.8 –37.2 µm.

Habitat in the Bocas del Toro region. Under coral ruble, 1 m depth.

Distribution. Panama (this study).

Remarks and discussion. This species appears to live in cryptic habitats and is therefore difficult to encounter. Its color is due to large granular cells. This species illustrates once again the close relationship of the genera Asteropus Sollas, 1888 and Stryphnus ( Sollas 1888; van Soest & Stentoft 1988; Hajdu & van Soest 1992; Uriz 2002a; Carvalho 2008). Indeed, if it were not for the presence of triaenes ( Fig. 11 C), this species would have been assigned to Asteropus . In the Caribbean, S. raratriaenus sp. nov. could certainly be mistaken with the shallow–water Asteropus brasiliensis Hajdu & van Soest, 1992, but the later has one size class of oxea, rare oxyasters (13–42 µm) and no triaenes. Our species is even closer to Asteropus ketostea de Laubenfels, 1950 from Bermuda, but the latter has thinner oxeas, smaller oxyasters (17–27 µm) and no triaenes. As for Asteropus niger , it has a dark choanosome, smaller oxeas II, larger oxyasters (42–98 µm), trichodragmata and no triaenes. The differences between Ancorina and Stryphnus are also ambiguous. Sollas (1888, p. 171) and Uriz (2002a) state that Stryphnus species can have amphiasters (e.g. Stryphnus fortis ) but in our opinion these are clearly just sanidasters with few actines on the main shaft. Sollas (1888, p. 171) and Uriz (2002a) also state that Stryphnus species have large oxeas (2–3 mm long, ca. 40–60 µm) but Ancorina species present the same range of oxea sizes, as well as Asteropus species. Both Stryphnus and Ancorina genera have similar spicule repertoires (large oxeas, triaenes, oxyasters and sanidasters) except for the presence of anatriaenes in Ancorina . We also noticed that Stryphnus generally possesses dichotriaenes, whereas these are rare in Ancorina . Furthermore, according to Sollas (1888, p. cxxxvii), Stryphnus has a more irregular spicule arrangement and no fibrous cortex (the cortex can be densely filled with large oxeas and triaenes) whereas Ancorina has a radially arranged skeleton and a more conspicuous cortex (often partly fibrous). We acknowledge that the definitions of these genera are still not satisfying at the moment, but until their comprehensive revision is initiated, our new species is assigned to Stryphnus based on the absence of anatriaenes, presence of dichotriaenes, its irregular spicule arrangement and lack of thick cortex. It is furthermore quite different from the only described Caribbean Ancorina species, namely Ancorina fenimorea de Laubenfels, 1934. A. fenimorea is known from rather deep water and has much larger sanidasters (60 µm) than our S. raratriaenus (average of 20.2 µm). As for Stryphnus species, they are all quite different from S. raratriaenus . Stryphnus fortis ( Vosmaer, 1885) , Stryphnus ponderosus ( Bowerbank, 1866) , Stryphnus mucronatus ( Schmidt, 1868) , Stryphnus unguiculus Sollas, 1886 and Stryphnus niger Sollas, 1886 all have smooth oxyasters and abundant dichotriaenes. Stryphnus progressus ( Lendenfeld, 1907) also has abundant dichotriaenes. S. raratriaenus sp. nov. is the seventh species of this genus described in the world and the first in the Caribbean. It should be noted that S. raratriaenus had numerous large dark granular cells, similar to those observed in our S. mucronatus and S. ponderosus specimens.

Despite substantial efforts, we were not able to obtain a COI sequence for this specimen. We strongly suspect that DNA contaminants block the PCR reaction. After extra cleaning of the DNA (precipitation, drying, extra washing with 70% ethanol), we nonetheless managed to obtain a partial 28S sequence.

Etymology. From the latin word ‘rara’ meaning ‘rare’ and the spicule name ‘triaene’.

Figures

FIGURE 11. Stryphnus raratriaenus sp. nov. [ZMBN 81642]: A. Holotype, alive, growing on coral rubble. A tangential cut in the specimen shows the whitish choanosome (arrow). Scale: 2 cm; B. Cross – section showing the skeletal architecture: cortex and choanosome. Arrow points to a dichotriaene. Scale: 1 mm; C. Detail of cross section (B) showing the dichotriaene. Note the large granular brown cells. Scale: 500 µm; D. Sanidaster. Scale: 2 µm; E. Oxyaster. Scale: 4 µm; F. Oxyaster with a dichotomous actine. Scale: 4 µm.

FIGURE 12. Spicule repertoire of Stryphnus raratriaenus sp. nov [ZMBN 81642]: A. Oxea I; B. Oxea II; C. Style; D. Dichotriaene; E. Oxyasters; F. Sanidasters. Scale 200 µm for A. Scale 50 µm for B – C – D. Scale 10 µm for E – F.