Homaxinella amphispicula

Austin, William C., Ott, Bruce S., Reiswig, Henry M., Romagosa, Paula & G, Neil, 2014, Taxonomic review of Hadromerida (Porifera, Demospongiae) from British Columbia, Canada, and adjacent waters, with the description of nine new species, Zootaxa 3823 (1), pp. 1-84 : 49-52

Homaxinella amphispicula (de Laubenfels, 1961)

Fig. 18 A–F

Syringella amphispicula de Laubenfels, 1961

Material examined. Holotype: USNM 22707, Griffin Bay, Washington, (48º 29′N, 122º 58′W), 45 m deep.

Other material: KML 1051, KML 225/70, Gordon Channel, BC, (50º 53.0'N, 127º 30.3'W), 91– 46 m depth, Sept. 16, 1970, coll. W.C. Austin; KML 1051, NM 126, Copper Bluffs, BC, (50o 06'N, 125o 16'W), 4–15 m depth, Apr. 16, 1978, coll. & photo N. McDaniel; VT19/81, Dark Cove, Jervis Inlet, BC, (49o 48.8'N, 123o 57.0'W), 36 m depth, Feb. 24, 1981, coll. W.C. Austin; KML 1049, KML sta. 161/70, Porlier Pass, BC, (49º 00.2'N, 123º 35.2'W), 12–15 m depth, Aug. 8, 1970, coll. W.C. Austin, 1 specimen; KML 1048, KML sta. 88/75, N. of Moreton I., Barkley Sd., BC, (48º 53.2'N, 125º 19.9'W), 30–37 m depth, Apr. 18, 1975, coll. W.C. Austin, 1 fragment; KML 1047, KML sta. 61/69, Bamfield, Barkley Sd., BC, (48º 50.1'N, 125º 08.1'W), 18 m depth, Jun. 2, 1969, coll. W.C. Austin, 1 specimen; KML 1050, KML sta. 94/82, N. tip of Pender I., in Navy Channel, BC, (48o 49.40'N, 123o 19.20'W), 20 m depth, May 27, 1982, coll. W.C. Austin; VT16/81, McCurdy Pt, Saanich Inlet, BC, (48o 37.7'N, 123o 31.1'W), 99 m and 76 m depth, Feb. 4, 1981, coll. V. Tunnicliffe/W.C. Austin; VT10/80, Squally Reach, Saanich Inlet, BC, (48o 33.4'N, 123o 32.5'W), 63 m depth, May 18, 1980, coll. V. Tunnicliffe/W.C. Austin; VT14/ 80, Elbow Pt., Saanich Inlet, BC, (48o 32.8'N, 123o 32.4'W), 65 m depth, Nov. 20, 1980, coll. V. Tunnicliffe.

Field images without vouchers: Fearney Pt., Agamemnon Channel, BC, (49º 38.7′N, 124º 05′W), photo N. McDaniel; Skookumchuk Narrows, BC, (approx. 49º 44.2′N – 123º 53.8′W), Jan. 1977, photo N. McDaniel; Turn I., BC, (approx. 50º 21′N, 125º 27′W), photo N. McDaniel; West Race Rock, Juan de Fuca Strait, BC, (48º 17.9′N, 123º 32.3′W), photo N. McDaniel; Dawley Passage, SE Meares I., BC, (49º 08′N, 125º 47′W), photo N. McDaniel.

Comparative material: Homaxinella subdula , USNM, ex. British Museum Nat. Hist. 65112 (R1384), Eddystone, U.K., (50º 10.8'N, 04º 10.8'W), May 1930, coll. M. Burton, ID M. Burton. Homaxinella subdula , USNM, ex. British Museum, Type R1384, East coast Lundy I, Outer Knoll, U.K., (51º 11.3'N, 4º 38'W), coll. J.D. George.

Description. Macroscopic features. Erect, branching with occasional anastomosing, root-like processes attached to the substrate ( Fig. 18 A, B). Consistency tough, wiry, with firm surface, but readily bent; size up to 10 cm with branch diameters of 5–10 mm; colour in life pale yellow.

Microscopic features. Axial skeleton is condensed, with bundles of spicules oriented parallel to the long axis of sponge ( Fig. 18 C). Extra-axial bundles of spicules extend from the axial spicules to the surface ( Fig. 18 D); they may project beyond the surface.

Spicules. Megascleres basically thin straight styles ( Fig. 18 E, F) with abrupt apices; some slightly swollen as incipient subtylotes. Size ranges are given in Table 10 .

Remarks. This species was originally placed in the genus Syringella by de Laubenfels (1961). Hooper (2002) noted that “ Syringella ” is not a valid taxon and the next available name is Parasyringella Topsent, 1928 which is a subgenus of Raspailia . “ Syringella ” amphispicula does not otherwise fit the diagnosis of Parasyringella which is unbranched and has bouquets of ectosomal styles. Most Raspailiidae have acanthorhabds and those which do not are otherwise different from “ S.” amphispicula . Two genera of Suberitidae are arborescent with branches similar to the stem: Plicatellopsis and Homaxinella . Both have an axially condensed skeleton. The former has well developed extra-axial bundles of spicules extending from the axis to the surface, while the latter has similarly oriented bundles which are poorly developed or absent after preservation (van Soest 2002). Plicatellopsis has, in addition, a pallisade of small spicules in the ectosome which is absent in Homaxinella . The spicules are tylostyles, with small tyles in Plicatellopsis and styles in Homaxinella (van Soest 2002).

The overall form of specimens examined by us looks much like Homaxinella subdula (Bowerbank, 1866) and is quite different from that in the type species of Plicatellopsis , P. arborescens . However, the branches of H. subdula are typically at right angles to the main stalk while they form roughly a 45º angle to the stalk in Homaxinella amphispicula . Van Soest et al. (2012) placed the de Laubenfels’ Syringella amphispicula species in Plicatellopsis .

Our specimens of both H. amphispicula and H. subdula have typical styles but also some megascleres which are clearly incipient subtylostytes ( Fig. 18 F, G). This includes the holotype of H. amphispicula which we examined, and the holotype of H. subdula when re-examined by Burton (1935). De Laubenfels (1961) stated that the spicules of H. amphispicula were exclusively tylostyles. However, no megasleres could be described as tylostyles in any of the material we examined including the holotype of H. amphispicula ( Fig. 18 C, D). Plicatellopsis spp. are characterized as having exclusively tylostyles.

The upper size limit and mean size of styles in H. amphispicula are considerably larger than those in H. subdula from the UK based on our specimens (above) and descriptions by Picton & Morrow (2005) and van Soest (2002). However, the styles fall within the large range given by Koltun (1959) of 195–863 Μm for some 75 specimens identified as H. subdula with a recorded range extending from the NE Atlantic to the Bering Sea, Okhotsk Sea, Sea of Japan, and the southern Kurils.

We reviewed the literature to assess whether or not populations in the NE Pacific are conspecific with one or more of the other species of Homaxinella described from the NW Pacific. Burton (1935) reported Pachaxinella (= Homaxinella ) subdula as occurring in the Sea of Japan and neighbouring areas but he provided no spicule sizes or information on branching. Five other species of Homaxinella have been described from the Sea of Japan. Homaxinella brevistyla Hoshino, 1981 (styles 300–470 µm) and Axinella echidnaea ( Ridley, 1884) (styles 400–1500 µm) can be excluded based on style size. Homaxinella tanitai Hoshino, 1981 ( Tanita 1968) (styles 370–630 µm) is likely excluded based on specimens being unbranched although they might be juveniles as the largest was 3.5 cm. Homaxinella infundibula Tanita et al. 1989 can be excluded based on spicule length (480–970 µm) and funnel shape. Homaxinella ramosimassa Tanita et al. 1989 can be excluded based on spicule length (570–980 µm) and the tight ramifying and anastomosing form. Two additional species from the Phillippines can be excluded based on form. Homaxinella acanthelloides Lévi, 1961 has hollow branches and Homaxinella domantayi Lévi, 1961 has flattened lamellar branches.

Conclusions. We do not agree with van Soest et al. (2012) in the reassignment of Syringella amphispicula to Plicatellopsis . Rather, we propose that S. amphispicula should be assigned to Homaxinella . The differences in form and megasclere size are sufficient to warrant separation of H. amphispicula from N. Atlantic populations of H. subdula at the species level. We suggest that the H. subdula of Koltun (1959) encompasses more than one species. The information available in the literature indicates that H. amphispicula is not conspecific with any species reported from the NW Pacific although it may be the species which Burton (1935) identified as Pachaxinella subdula in the Sea of Japan and the Sea of Okhotsk.

Bathymetric range. 10 to 70 m depth.

Geographic distribution. Washington ( USA) and British Columbia ( Canada).

Ecology. H. amphispicula occurs on rock but is also attached to shells on otherwise soft bottoms and ranges from low to high tidal current environments. It and Aaptos simplex are the first recognizable sessile species occurring above anoxic conditions in the Saanich Inlet fjord. Small (2–3 cm) individuals are erect, cylindrical and unbranched. Like many other suberitids H. amphispicula can contract to a considerable degree.

Figures

FIGURE 18. Homaxinella amphispicula (de Laubenfels, 1961). A, expanded specimen, scale bar approx. 2.5 cm; B, contracted specimen, scale bar 1.3 cm; C, axial skeleton in cross section, scale bar 500 µm; D, extra-axial bundles of spicules running to surface, scale bar 500 µm; E, styles and subtylostyles sta. 94 / 82, scale bar left 100 µm, middle and right 10 µm; F, styles and subtylostyles of holotype H. amphispicula USNM, scale bar left 100 µm, middle and right 30 µm; G, styles of Homaxinella subdula from the UK, scale bar left 200 µm, middle and right 30 µm.

Tables

TABLE 10. Homaxinella spp. styles & subtylostyles range, mean length & width in µm.

Location	Sta. 94/82 amphispicula	No. 126 amphispicula	Holotype amphispicula	Eddystone, UK subdula
Ectosome length	260–(536)–710 N=25	270–(540)–710 N=25
Ectosome width	6–(11.5)–20 N=25	4.6–(8.8)–14 N=25
Choanosome length	270–(621)–830 N=25	325–(605)–850 N=25
Choanosome width	7–(16.3)–20 N=25	5–(11)–16 N=25
*Combined length	260–(579)–830 N=50	270–(573)–850 N=50	360–(571)–760 N=15	270–(416)–550 N=10
*Combined width	6–(13.9)–20 N=50	4.6–(9.9)–16 N=50	6–(12.4)–17.5 N=15	3.8–(4.7)–7.5 N=8