Dysidea kenkriegeri, 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 : 477-480

Dysidea kenkriegeri n. sp.

( Fig. 17 )

Material examined. Holotype: ZSM 20150393, collected by Dave Somerton with a research survey bottom trawl (haul #15) aboard the FV Alaska Provider; 1 June 2013, 93 m depth, 10.7 km south of Sedanka Island, east end of Unalaska Island, eastern Aleutian islands, Gulf of Alaska (53°36.6380' N, 166°12.4800' W). Water temperature = 4.5°C. Complete specimen in ethanol.

Description. Habitus: The sponge consists of a group of agglutinated tubes starting from a single stalk with maximum height of 9.7 cm ( Fig. 17 A). The stalk is 1 cm in diameter with a length of 1.8 cm before the sponge widens to a central area where seven tubes diverge. Single tubes are 0.8 to 1.4 cm in diameter with lengths between 2.7 and 4 cm. Thickness of the tube walls varies from 2–4 mm. The consistency of the tubes is soft and elastic while the stalk is hard and only slightly elastic. The color is light brown to beige and the surface is smooth and velvety, openings are recognisable at the top the tubes only ( Figs. 17 B & C).

Skeletal structure: The choanosome consists of a meshwork of spongin fibers loaded with foreign spicules and sediment, mesh-sizes variable, 130–880 µm. Sections perpendicular to the surface reveal smaller meshes, approximately 100–200 µm in diameter, in an area from the surface down to 300–-500 µm into the interior of the sponge, then larger meshes of mostly elongated rectangular shape dominate ( Fig. 17 D). Ascending spongin fibers are 120–250 µm in diameter, connecting fibers are 40–150 µm ( Figs. 17 E & F). Spongin fibers ascend obliquely to the surface. The ectosome is also a reticulation of spongin fibers cored by foreign particles and connecting the fibers reaching the surface. Ectosomal fibers measure 35–80 µm in diameter, forming a network with diameters of 50–350 µm.

Discussion. Sponges of the orders Dictyoceratida and Dendroceratida are mainly known from warmer seas. Our record of a species of Dysidea is the first for the order Dictyoceratida from Alaska. There are two other records of the genus from the North Pacific: D. minna Hoshino, 1985 from the Sea of Japan and D. fragilis ( Montagu, 1814) sensu Koltun, 1959 reported from the Arctic Ocean (Barents Sea including the White Sea, the Kara Sea, and Laptev Sea) and the Sea of Japan. The geographical records from Koltun (1959) are listed as inaccurate in the WPD although quite possibly a species of Dysidea but not D. fragilis . As Koltun (1959) described a Dysidea with a conulose surface, it is different from the species presented here. If the WPD is correct and Koltun´s record is not conspecific with D. fragilis then the species reported from Koltun probably is another undescribed species of Dysidea from this region.

The species described here is indeed unusual for the genus as it has a smooth surface. Dysidea are thickly encrusting, massive, or branching sponges often with a marked conulose surface and a distinct net or web-like surface pattern, interconnecting between conules ( Cook & Bergquist, 2002). The skeleton consists of a regular, usually rectangular arrangement of concentrically laminated primary and secondary fibres (all axially to fully cored); the former oriented perpendicular to the sponge surface ( Hooper and Van Soest, 2002). The WPD lists 57 valid species of Dysidea with only five occurring in the North Pacific and North Atlantic Oceans. This is the first record of the order Dictyoceratida from Alaska. D. kenkriegeri differs from these species in the following characters:

D. amblia (de Laubenfels, 1930): Northeast Pacific Ocean (Baja Mexico to British Columbia). A digitate, somewhat ramose sponge, drab in alcohol, 20–30 cm in height and 1 cm in diameter, the surface is superficially conulose, conules less than 1 mm high and less than 1 mm apart. Ascending fibers are 100–200 µm in diameter, connecting fibers are 10–25 µm in diameter and usually free from inclusions (de Laubenfels, 1932, p. 123).

D. anceps ( Hyatt, 1877) : Locality unknown. A sponge with inelastic primary fibres and the secondary fibres are free from inclusions and of “dark horn color” ( Hyatt, 1877, pp. 539–540).

D. dendyi ( Ferrer Hernandez, 1923) : Northeast Atlantic Ocean (off the coast of Spain). A spherical sponge with a diameter of 10 cm and a conulose surface.

D. fragilis ( Montagu, 1814) : The type specimen from the Atlantic Ocean and Mediterranean Sea. A grey colored sponge with a strongly conulose surface.

D. minna Hoshino, 1985 : Northwest Pacific Ocean (around Japan). A funnel-shaped sponge with several short stalks. Judging from the photo (p. 50) the surface is corrugate, conules are up to 1 mm high and thick. Ascending fibres are 400–500 µm in diameter, connecting fibers are 50–80 µm in diameter.

D. fragilis sensu Koltun, 1959 : North Pacific Ocean. A record which is inaccurate according to the WPD. This species is grey to orange colored and up to 20 cm in height. It has a conulose surface and is stiff and brittle in consistency. Primary fibres are 200–1000 µm in diameter, secondary fibres are 100–250 µm with meshes 400– 2000 µm in width.

Dysidea kenkriegeri sp. n. is unique within the genus in its light brown to beige color and its smooth, nonconulose surface.

Etymology. Named after Ken Krieger, retired fisheries research biologist for the Alaska Fisheries Science Center, NOAA, National Marine Fisheries Service ( United States), and from the German word "Krieger" meaning "warrior." Ken was a not only a pioneer of Gulf of Alaska deep-sea research, but true to his namesake, a warrior who fought for the continuation of that work.

Figures

FIGURE 17. Dysidea kenkriegeri n. sp. A. Holotype. Square is 1 cm. B. View from above showing openings of tubes. Square is 1 cm. C. Section through tube. Square is 1 cm. D. Section perpendicular to surface. Surface is on the left. Below the surface the reticulation of spongin fibers cored with foreign material is denser than in the deeper parts (upper right). Scale bar is 500 µm. E. Reticulation of spongin fibers just below the ectosome, clear spongin and coring sediment clearly visible. Scale bar is 200 µm. F. Ascending spongin fibers and connecting fibres are loaded with foreign material. Scale bar is 200 µm.