Raspailia (Hymeraphiopsis) fruticosa, Lehnert, Helmut & Stone, Robert P., 2015

Lehnert, Helmut & Stone, Robert P., 2015, New species of sponges (Porifera, Demospongiae) from the Aleutian Islands and Gulf of Alaska, Zootaxa 4033 (4), pp. 451-483 : 477

Raspailia (Hymeraphiopsis) fruticosa n. sp.

( Fig. 16 )

Material examined. Holotype: ZSM 20150392, collected by Jim Stark with a research survey bottom trawl (haul #193) from the FV Ocean Explorer; 27 July 2012, 228 m depth, 30.6 km SSE of Fox Beach Point, Shemya Island, Semichi Islands, western Aleutian Islands, North Pacific Ocean (52°26.5920' N, 174°18.1740' E). Water temperature = 3.7°C. Complete specimen in ethanol.

Description. Habitus: Pale ochre-colored, bushy sponge with a height of 7 cm and a diameter of 4.5–5.5 cm ( Fig. 16 A). It grows on a bivalve ( Astarte sp.) shell with several points of attachment.

Skeletal structure: There is no special ectosome developed. The choanosome is plumose, with the longitudinal axis of the sponge formed by polyspicular tracts of styles which diverge into spicule tracts running obliquely to the surface, ending there without getting much broader. Spicule tracts of styles are echinated by numerous acanthotylostyles, standing perpendicular, obliquely or even parallel to the tracts ( Figs. 16 B & C).

Spicules: Smooth styles, 956–1520 x 22–44 µm ( Fig. 16 D), acanthotylostyles with a smooth, very pronounced tyle, characteristic for the subgenus, 150–234 x 18–33 µm ( Fig. 16 E), with the tyle being the thickest part of the spicule.

Discussion. Assignment to the subgenus Hymeraphiopsis is justified due to the presence of the echinating acanthostyles with smooth and very swollen tylote bases; a characteristic diagnostic for the subgenus ( Hooper, 2002d). This is only the second species for this subgenus, the only other species known, the type species, Raspailia (Hymeraphiopsis) irregularis Hentschel, 1914 , is from the Antarctic Region. The characteristics of this species (after Hooper, 2002d) are: styles, 1969–3016 x 35 –54 µm, styles or anisoxeas, 435–712 x 2–11 µm, and acanthostyles, 181–301 x 12–24 µm). R. fruticosa differs from the type specimen in growth form: while the type is bushy without a dominating axis the new species has only short side-branches diverging from a main axis. It has smaller and generally thinner styles, smaller and thicker acanthostyles, and lacks the ectosomal oxeas.

Etymology. From the Latin fruticosus—bushy, referring to the habitus of the sponge.

Figures

FIGURE 16. Raspailia (Hymerhaphiopsis) fruticosa n. sp. A. Holotype on a bivalve shell (Astarte sp.). Grid marks are 1 cm. B. Polyspicular tract with echinating acanthotylostyle. Scale bar is 100 µm. C. Two echinating acanthotylostyles. Scale bar is 100 µm. D. Smooth choanosomal style. Scale bar is 100 µm. E. Echinating acanthotylostyle among styles. Scale bar is 20 µm.