Dragmacidon kishinensis, Austin, William C., Ott, Bruce S., Reiswig, Henry M., Romagosa, Paula & McDaniel, Neil G., 2013

Austin, William C., Ott, Bruce S., Reiswig, Henry M., Romagosa, Paula & McDaniel, Neil G., 2013, Two new species in the family Axinellidae (Porifera, Demospongiae) from British Columbia and adjacent waters, ZooKeys 338, pp. 11-28 : 17-21

Dragmacidon kishinensis sp. n. Fig. 2

Etymology.

After the ancient First Nation (aboriginal) village site kiix?in (pronounced keeshin) which includes Execution Rock Cave, Barkley Sound, BC, where a specimen was collected in the low intertidal.

Material examined.

Holotype: RBCM 013-00115-001, KML1111, PEI 44, Steep I., Discovery Passage, BC, (50°4.94'N, 125°15.35'W), 30 m depth, coll. N. McDaniel, Feb. 26, 1976, 1 specimen & in situ image. Paratype: CMNI 2013 –- 0002, KML1113, KML 139/80, Limestone I., BC, (ca. 52°55'N, 131°36'W), 3 m depth, coll. W.C. Austin, July 4, 1980, 1 specimen.

Other material. KML1112, PEI 130, Copper Cliffs, Discovery Passage, BC, (50°6.40'N, 125°15.35'W), 15 m depth, coll. N. McDaniel, Apr. 16, 1978, 1 speci men; KML1114, PEI 53, Grilse Pt. Texada I, BC, (49°48.03'N, 124°35.79'W), 10 m depth, coll. N. McDaniel, Mar. 13, 1977, 1 specimen; KML1116, PEI 49, Vivian I., BC, (49°50.28'N, 124°41.96'W), 15 m depth, coll. N. McDaniel, Apr. 10, 1976, 1 specimen; KML1121, Sta. no data, Rennell Sound, BC, (ca. 53°24'N, 132°44'W.), depth no data, coll. M. LeBlanc, Apr. 14, 1989, 2 specimens; KML1294, KML 127/76, Execution Rock Cave (48°48.9'N, 125°10.6'W), 0.2 m height, coll. W.C. Austin, July 28, 1976, 1 specimen; RBCM 976-1081, Entrance I., Tasu Sound, BC, (ca. 52°46.04'N, 132°03.55'W), depth no data, coll. P. Lambert, 1976, 1 specimen; RBCM 974-230-3, Brundige Inlet, BC, (ca. 54°37'N, 130°50'W), coll. P. Lambert, June 19, 1974, depth no data.

Description.

Macroscopic features. Thick, encrusting, unbranched form, 20 × 20 × 4 cm thick in holotype. Surface with abundant, small (1 mm diam.) and large (1 cm × 1-3 cm) irregular tubercles (Fig. 2A). Consistency preserved: moderately compressible but tough. Oscula numerous, flush with surface and ranging from 0.2 to 4 mm diameter. Aquiferous canals tangential with those near surface leading to oscula. Orange colour in life (Fig. 2A), light tan in alcohol.

Microscopic features. Ostia about 0.5 mm diam. in situ penetrate a thin surface membrane between lobes (Fig. 2B); weakly developed plumoreticulate skeleton of 50-100 um diameter fibers extend from base to surface; uni or pauci spicular cross connections (Fig. 2C); halichondroid (confused) skeleton toward the base. No specialized ectosomal skeleton and no axial skeleton.

Spicules.

Spicule types include straight oxeas (Fig. 2E), slightly curved styles (Fig. 2G), and strongyles. Oxea tips gradually and sharply pointed; style heads smoothly rounded, slightly narrower than main style body. Styles and oxeas mostly slightly curved or straight; a few strongly curved or sinuous. Strongyles uncommon to rare.

Table 2 lists spicule dimensions.

Oxea and styles in about equal numbers, and of equivalent length. A second category of styles (styles II), while of comparable length to style 1, much thinner. Also much less abundant in two specimens and absent in eight other specimens. Strongyles of comparable width to oxeas and style I, but shorter; few in number in seven specimens and absent in three other specimens. No loose raphids or trichodragmas observed.

Remarks.

The paucity of thin styles suggests that these are developmental stages. The strongyles may be anomalies or, alternatively, may be associated with one area of the sponge such as the oscula or the area of attachment to the substrate.

The choanosomal skeleton of Dragmacidon kishinensis sp. n. is only weakly plumose. In our material the linear tracts are also less dense than in the type species Dragmacidon agariciformis (Dendy, 1905). In other respects it fits the diagnosis for Dragmacidon which includes species that are thickly encrusting, the surface with tubercles, ectosome without a specialized skeleton, and skeleton not differentiated into an axial or extra-axial region. It also has both oxeas and styles of similar form and in similar numbers.

It does not fit the diagnosis for Axinyssa where the choanosomal skeleton is confused; and where the spicules may be oxeas, strongyloxeas or stylote modifications of oxeas ( Erpenbeck and Van Soest 2002)

Twenty-six species of Dragmacidon are presently recognized ( van Soest et al. 2005: World Porifera Database, accessed February 2013).

Eight species can be excluded from being conspecific based on their having trichodragmas which are lacking in Dragmacidon kishinensis sp. n. All but two of the remaining species without trichodragmas have oxeas and styles which are at least 50% shorter than those in Dragmacidon kishinensis sp. n. The first exception is Dragmacidon oxeon which has styles and oxeas only slightly shorter than those in Dragmacidon kishinensis sp. n.; however, it differs from Dragmacidon kishinensis sp. n. in having a well developed detachable membrane. The second exception is Dragmacidon egregium (Ridley, 1881) which has two classes of styles, one 650-900 µm in length but the other as well as the oxeas only up to 400-450 µm in length.

The weakly developed skeleton is similar to that in Dragmacidon grayi (Wells & Wells in Wells et al. 1960) as described by Alvarez et al. (1998).

Dragmacidon kishinensis sp. n. shows some similarities to species of Axinyssa ( Halichondridae ) including a disorganized skeleton with, in some species, vaguely ascending vertical tracts toward the periphery. Spicules include oxeas and/or strongyloxeas, here considered to have a fusiform shaft which is pointed at one end and rounded at the other. Dragmacidon kishinensis sp. n. spicules consist of oxeas and styles, the latter are isodiametric rather than being fusiform. There are 28 described species of Axinyssa (van Soest et al. consulted August 2013). They are nearly all tropical.

Conclusions.

Based on the comparisons listed in Table 3, our Dragmacidon is a new species. The combination of spicule types and sizes in Dragmacidon kishinensis sp. n. do not match any other Dragmacidon species described. The reduction of a plumoreticulate skeleton and evidence of unoriented spicules suggests a possible affinity with Axinyssa spp. but the latter have only oxeas or strongyloxeas while our species has both oxeas and styles as found in some Dragmacidon spp. Finally, we would not expect to find an Axinyssa sp. in the cold temperate waters of British Columbia.

Bathymetric range.

One intertidal record (0.2 m above 0 m [low tide]) in a cave; otherwise 3 m to 30 m depth.

Zoogeographic range.

Recorded from Barkley Sound (49°N) to Rennell Sound (53°N), BC.

Ecology.

Dragmacidon kishinensis sp. n. is recorded from high wave or high current energy habitats. The tough, encrusting, non branching form would be structurally adaptive for the physical impacts of strong water movement.