Sarcotragus scalaris, Sim & Lee & Kim, 2016

Sim, Chung Ja, Lee, Kyung Jin & Kim, Hyung June, 2016, Ten new species of genus Sarcotragus (Demospongiae: Dictyoceratida: Irciniidae) from Korea, Journal of Species Research 5 (3), pp. 443-458 : 452

9. Sarcotragus scalaris n. sp. ( Figs. 10 , 11 )

Type specimen. Holotype (NIBRIV0000554218), Korea: Jikgudo, Chuja­myeon, Jeju­si , Jeju­do, 5 Nov 2009, Kim HS, by SCUBA, Depth 15 m, deposited in the NIBR.

Description. Thick round mass, size up to 12× 7 × 4 cm. Surface covered with porous thin filamentous membrane. Conules easily distinct, but not sharp. Numerous oscules, 3­7 mm in diameter, open on sponge surface. Colour beige in life, changed to dark brown after collection. Texture very soft and compressible. Choanosome not lacunose. Surface fibres thinner than ladder-like choanosomal fibres.

Skleton: Primary fibres, 300-700 μm in diameter, dense cylindrical fascicles. Secondary fibres, various size of fibres in web type, 700-1000 μm in diameter, and 200- 400 μm in diameter, in branch type. Filaments, 5-7 μm in diameter, terminal knobs, 10­12 μm in diameter.

Etymology. This species is named after the shape of ladder­like choanosome skeletal structure.

Remark. This species is very similar to Sarcotragus sucinum n. sp. in colour change upon collection, but it is big different in skeletal structure. Surface fibres of S. sucinum n. sp. are thicker than this new species. S. sucinum n. sp. have prismatic skeletal fibres in choanosome, but this new species has ladder-like skeletal fibres at the choanosome. The surface has porous filamentous membrane.

Figures

Fig. 10. Sarcotragus scalaris n. sp. A, entire animal; B, closed surface; C, filamentous membrane with pore; D, choanosomal skeletal struc­ ture; E, thick primary fibres; F, branched secondary fibres. Scale bars:A =2 cm, B=20cm, C, E, F=100 μm, D=200μm.

Fig. 11. Sarcotragus scalaris n. sp. A, primary fibres; B, secondary web between primary fibres; C, secondary fibres branch; D, small pri­ mary fibres; E, secondary fibres web; F, large skeletal structure at the base of sponge. Scale bars:A-E=100 μm, F=1 cm.