Callyspongia (Callyspongia) mucosa, Lehnert, Helmut & Stone, Robert P., 2013

Lehnert, Helmut & Stone, Robert P., 2013, Four new species of Haplosclerida (Porifera, Demospongiae) from the Aleutian Islands, Alaska, Zootaxa 3700 (4), pp. 573-582 : 575-576

Callyspongia (Callyspongia) mucosa n. sp.

(Fig. 2)

Material examined. Holotype: USNM# 1202116, collected by Jim Stark on 16 August 2012 at 51°52.29´N, 177°43.26´E, 8.8 km S of Orient Point, Little Kiska Island, eastern Aleutian Islands, Alaska, USA, at a depth of 106 m and a water temperature of 4.5°C; paratype: USNM# 1202117, collected by Jay Orr on 4 July 2012 at 51°40.75´N, 177°11.26´W 4.2 km SW of Cape Chlanak, Kanaga Island, central Aleutian Islands, Alaska, USA, at a depth of 84 m and a water temperature of 4.5°C.

Description. Both specimens thickly flabellate to lobate, light brown to beige in color, with smooth, extremely slimy surfaces (Figs. 2A & B). The consistency is soft and elastic, but rather resilient and difficult to tear. The holotype is approximately 18 cm in width, 12 cm in height, and consists of 3–4 lobes attached basally and 1.5–2 cm thick, and slightly tapered at the margins. The specimen has circular oscules, not so obvious, slightly raised and 2– 4 mm in diameter. The base narrows to about 4 cm where the sponge appears to have been attached to hard rock (larger than pebble). An unidentified brown demosponge grows on the base of the specimen (Fig. 2A). The paratype is approximately 23 cm in width, 16 cm in height, and consists of 4–5 lobes similar to those of the holotype. The specimen has circular oscules, more obvious than in the holotype, slightly raised and 2–4 mm in diameter. This specimen also narrows somewhat at the base where it was attached to rock larger than pebbles. Microscopically examined sections of both specimens revealed unusually abundant diatoms and less abundant radiolarians (Fig. 2F). The ectosome consists of a fine reticulation of secondary spongin fibres without coring spicules. These fibres have diameters of 15–25 µm and form meshes with oval pores with diameters of 45–70 x 85 – 130 µm (Fig. 2C). There is also a coarser, polygonal mesh of primary spongin fibres, 20–35 µm in diameter with a mesh size of 300–520 µm (Fig. 2C). In the corners of the polygons are spicule brushes, perpendicular to the surface, consisting of the ends of ascending paucispicular tracts. The spongin fibres of the polygonal mesh are partially cored by oxeas, partially made of pure spongin. The choanosome consists of ascending paucispicular tracts which are completely embedded in clear spongin. These tracts are at intervals of 150–500 µm and are connected by single spicules, also embedded completely in spongin and are at intervals of 120–400 µm, forming a rectangular reticulation (Figs. 2D & E). The oxeas measure 205–283 x 11–21 µm and are straight or more often slightly bent with acute points (Fig. 2F).

Discussion. The World Porifera Database (WPD, Van Soest et al. 2013) lists 261 records for the genus Callyspongia and 24 species within the subgenus Callyspongia . There are no previous records of the subgenus Callyspongia from the North Pacific Ocean, Bering Sea, and the Arctic Ocean. The seas of Australia and New Zealand harbour nine species of the subgenus Callyspongia , the Indian Ocean and the Caribbean each harbour five species, three species are recorded from West- and South-Africa while Antarctic waters and the Red Sea each contain one known species. Additionally, the WPD lists 108 species of Callyspongia without subgeneric assignment. Along the North American Pacific coast there is only one record from California, Callyspongia californica Dickinson, 1945 . C. californica has oxeas with a maximum size of 150 x 5 µm which are much shorter and thinner than in C. mucosa . The genus Callyspongia is otherwise not known from the North Pacific Ocean, Bering Sea, or Arctic Ocean, so the new species represents the northernmost record of the genus.

There are eight species without subgeneric assignment reported from the Sea of Japan to compare with C. mucosa . These eight species all have much shorter and thinner oxeas and are generally known from shallower depths: C. ariakensis Tanita, 1961 is flabellate but has oxeas measuring 90–100 x 4–5 µm. C. bispicula Tanita, 1961 has two categories of oxeas, large (140–160 x 7–11 µm) and small (100–125 x 4 µm). C. ecklonia Hoshino, 1981 has oxeas measuring 60– 90 x 2–5 µm. C. flabelliformis, Tanita, 1968 has oxeas 90–100 x 3–4 µm. C. patula Hoshino, 1981 has oxeas 125–150 x 6–8 µm. For the description of C. poculum (Carter, 1885) , no spicule measurements, skeletal architecture details, nor figures were provided in the original description. Carter (1885) mentions (p.402–403) that “the same form of spicule predominates instead of the keratose element. The spicules are oxeas which are described as acerate, fusiform, smooth, curved, and sharp pointed”. He describes the species as “light grey in colour, which causes them to resemble the open vase-like form called by Dr. Bowerbank “ Isodictya infundibuliformis ” … but not being the same, it might, for distinction´s sake, be termed “ Tuba poculiformis ”. We regard Carter´s Tuba poculiformis as unrecognisable but we exclude conspecifity as the species described by Carter differs from C. mucosa in being light grey and vasiform. C. taupea (Tanita & Hoshino 1989) also has smaller oxeas measuring 150–170 x 12–14 µm. Finally, C. waguensis Tanita, 1961 has been reported from shallow water and has small oxeas (98–123 x 4–8 µm).

The specimens were collected remotely with a research trawl so we did not visually observe the seafloor habitat where the specimens resided. However, both specimens were attached to hard rock with diameters larger than pebbles so would indicate that this species is found in relatively complex habitat at depths between 84 and 106 m.

Etymology. The species name is derived from the Latin noun “mucus” meaning slime, as all specimens were extremely slimy.

FIGURE 2. Callyspongia (Callyspongia) mucosa n. sp. A. Holotype, grid marks are 1 cm 2. B. Paratype, grid marks are 1 cm 2. C. Ectosome: fine reticulation of secondary spongin fibres without coring spicules and a coarser net of primary spongin fibres partially with coring oxeas. Scale bar is 250 µm. D. Choanosome: rectangular net of ascending paucispicular tracts connected by single spicules, tracts and spicules embedded in spongin. Scale bar is 250 µm. E. Choanosome close-up showing spongin encasement of tracts and single spicules. Scale bar is 250 µm F. SEM photo of oxeas. Circular objects on the left are diatoms, abundantly observed on the specimens. Scale bar is 10 µm.