The genera Stelletta Schmidt, 1862 and Stryphnus Sollas, 1886 are contained in the family Ancorinidae. This family is characterized by the long-rhabdome triaenes and oxeas as megascleres and euasters, sanidasters or microrhabds as microscleres. The genus Stelletta is characterized by presence of long-shafted triaenes as megascleres and euasters without marked centrum as microscleres. Twelve Stelletta species have been reported in Korean waters so far (Shim and Sim, 2009). The genus Stryphnus, which was first recorded in Korea is characterized by the presence of large oxeas and orthotriaenes, plagiotriaenes or dichotriaenes as megascleres, and euasters and amphiasters or sanidasters as microscleres (Hooper and van Soest, 2002). Accoding to the World Porifera Database (WPD, http://wwww.marinespecies.org/porifera/), fifteen species of the genus Stryphnus are reported from the world.
Specimens were collected from a depth of 24-30 m at Jejudo and Chuja-do by SCUBA diving from July 2003 to June 2010. A holotype has been deposited in the National Institute of Biological Resources (NIBR), Incheon, Korea, and paratypes have been deposited in the Natural History Museum of Hannam University (HUNHN). The colour and texture were described before preservation. Identification was based on the morphological characteristics, skeletal structure, shape and size of spicules. Skeletal structure and spicules were examined by using microscopy and scanning electron microscopy. The length and width of 20 spicules were measured for each spicules type. The procedure of dissociating spicules followed Rutzler (1978).
Phylum Porifera Grant, 1836
Class Demospongiae Sollas, 1885
Subclass Tetractinomorpha Levi, 1953
Order Astrophorida Sollas, 1888
Family Ancorinidae Schmidt, 1870
Genus Stelletta Schmidt, 1862
[Fig. 1.] Stelletta subtilis. A, Entire animal; B, Skeleton; C, Cortex; D, Megasclere (a, oxea; b, anatriaene; c, dichotriaene); E, Head of dichotriaene; F, Head of anatriaene; G, H, Tylasters. Scale bars: A=5 mm, B, D=1 mm, C=500 μm, E=300 μm, F=50 μm, G=5 μm, H=10 μm.
1*Stelletta subtilis (Sollas, 1886) (Fig. 1)
Myriaster subtilis Sollas, 1886: 188; 1888: 133, Pl. 14, figs. 23-28; Hoshino, 1971: 22.
Stelletta subtilis: Lendenfeld, 1903: 48; Hoshino, 1981: 247, fig. 32.
Material examined. Korea: Jeju-do, Beom-seom, 28 Jul 2003, Lee KJ, by SCUBA diving 24 m depth; Jeju-do Island, Hang-won, 5 Jun 2010, Kim BI, by SCUBA diving 20 m depth, deposited in the HUNHN.
Description. Small round shape, 1.5 cm in diameters. Oscule only one, 1 mm in diameter, opened at center of sponge. Surface covered with pores like sieves. Texture hard and incompressible. Colour pale pink in life, beige in alcohol. Skeleton hard to distinguish between cortex and choanosome. Radially arranged with bundles of oxeas, dichotriaenes and anatriaenes. Clads of dichotriaenes and anatriaenes run toward surface. Tylasters scattered in sponge.
Spicules. Megasclere oxeas sharply pointed ends, 1,490- 2,360 by 12-40 μm. Anatriaenes rhabds sharply pointed clads, rhabds 1,580-2,260 by 10-14 μm, clads 50-80 by 8-12 μm. Dichotriaenes sharply pointed clads, rhabds 960- 2,100 by 28-60 μm, clads 140-340 μm. Microscleres tylasters, 12-24 spined rays, spines at the ends, 7-10 μm diameter.
Distribution. Korea (Jeju-do), Japan (Kobe).
Remarks. The shape, colour, skeleton and composition of spicules of our specimen are almost identical to those of Sollas (1886) and Hoshino (1981).
1*Genus Strypnus Sollas, 1886
2*Stryphnus sollasi n. sp. (Figs. 2,3)
Type specimen. Holotype (NIBRIV0000260248), Jeolmyeongyeo, Chuja-do, 23 May 2005, Lee KJ, by SCUBA 30 m depth, deposited in the NIBR. Paratype (NIBRIV0000260 248-1, NIBRIV0000260248-2), collected with holotype, deposited in the HUNHN.
Description. Massive shape, size up to 8×6.5×4.5 cm. Surface completely covered with Poecillasta sp. Oscule not apparent due to other sponge, Poecillastra sp. Texture compressible. Colour externally unknown due to Pocillastra sp. at surface, internally white. Cortex 2 mm in thick, clads of dichotriaenes and amphirasters arranged. Choanosome oxeas, rhabds of dichotriaenes and oxyasters scattered. Several cavities, 1-3 mm in diameters scattered in sponge.
Spicules. Megascleres oxeas sharply pointed ends, 880- 1,640 by 10-70 μm. Dichotriaenes sharply pointed clads, rhabds 220-730 by 18-55 μm, clads 105-300 μm. Microscleres oxyasters with 8 thin rays, spines at the ray, two size categories, large oxyasters 75-130 μm diameter and small oxyasters 30-55 μm diameter. Amphirasters 8-28 rays, spines at the surface, 10-15 μm diameter.
Etymology. This species is named after Professor W. J. Sollas who erected the genus stryphnus.
Remarks. This new species is similar to Stryphnus niger Sollas, 1886 in the composition of spicules, however they differ in colour and spicule size. This new species has smaller oxeas and larger oxyasters than those of S. niger. This new species has two size categories of oxyasters but S. niger has one size category of oxyasters. The colour of S. sollasi n. sp. is white, but the latter puce black.
Korean name: 1*작은별해면(신칭)
Korean name: 1*수렴해면속(신칭), 2*솔라스수렴해면(신칭)