Tentorium aff. semisuberites ( Schmidt, 1870 )

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 : 41-44

Tentorium aff. semisuberites ( Schmidt, 1870)

Fig 15 A–J

Northern Hemisphere: Thecophora semisuberites Schmidt 1870 ; Tentorium semisuberites Vosmaer 1885 ; Boury-Esnault 2002; Plotkin 2004.

Southern Hemisphere: Ridley and Dendy 1887; Boury-Esnault and van Beveren 1982; Plotkin & Janussen (2008).

Material examined. KML 1341, NM 294, Sakinaw Rock, Sechelt Inlet, BC, (49° 34.075′N, 123° 48.238′W), 24 m depth, Sept. 27, 2012, coll. N. McDaniel; KML 1300, KML 1301, NM 275, supplementary ident. Nos. T1, and T2, Sakinaw Rock, Sechelt Inlet, BC, (49° 34.075′N, 123° 48.238′W), 24 m depth, Feb. 16, 2012, coll. N. McDaniel; KML 1342, Sakinaw Rock, Sechelt Inlet, BC, (49° 34.075′N, 123° 48.238′W), 24 m depth, Dec. 11, 2012, coll. N. McDaniel; KML 1343, Sakinaw Rock, Sechelt Inlet, BC, (49° 34.075′N, 123° 48.238′W), 24 m depth, Dec. 11, 2012; coll. N. McDaniel.

Field images lacking vouchers at same location as above: taken of T4, Feb. 20, March 6, Apr. 12, May 10, and Sept. 27, 2012; T3, May 10, 2012, photos by N. McDaniel and L. Lehmann, first recorded in Agamemnon Channel, BC, at 15–18 m depth, Nov. 17, 2002 by A. Lamb and B. Hanby (photo page 78, Lamb & Hanby 2005). The above two locations are 20 km apart.

Description. Macroscopic features. KML 1341, expanded in field ( Fig. 15 A): columnar, somewhat arched on top of column; diameter 6 mm; pores occupy most of space at top of column, none on the sides, single osculum in centre on a papilla. Contracted, preserved in 95% ethyl alcohol: hemispherical, 4 mm high, 3.2 mm in diameter with a basal skirt where the sponge is attached to the substrate around the periphery; unable to distinguish osculum. In field observed rapid (about 5 second) contraction ( Fig. 15 B) following mechanical disturbance of water with concomitant change from cylindrical to hemispherical shape and contraction of pores so no longer apparent. Attached to bedrock. Colour alive white on top of cylinder, light tan on sides of cylinder. KML 1300, KML 1301. Funnel shaped ( Fig. 15 C) 5 mm diameter at base, apex of funnel decreases in width to a thread-like tendril (approx. 200 µm in diameter, up to 40 cm long). No ostia are visible; the funnel apex occupies the position of the osculum and nipple shown in Fig. 15 A. There are periodic swellings along the tendril towards its distal end. These are approximately 300 µm in diameter by 700 to 800 µm long. Between the swellings the tendril is approximately 100 µm in diameter. In KML 1342 and KML 1343 the sponges are both cone shaped, 3.6 mm diameter at base by 12 mm high, each with an incipient tendril about 2.5 cm long; two spheres are attached at the end of one tendril.

Microscopic features. KML 1341 ectosome with a fence of short tylostyles oriented with pointed ends out and extending beyond the surface 200 µm; choanosome with longitudinal tracts running from the base to the apex of the sponge ending in brushes about 100 um across. Form a solid layer around the periphery of the sponge ( Fig. 15 E). KML 1300 the longitudinal fibre tracts continue into funnel and out along the tendril where they form the wall of the tendril while short tylostyles project out at right angles to the tendril.

Spicules. KML 1341 non-tendril stage.

KML 1301 tendril stage: main body (N=20) KML 1301 tendril stage: tendril (N=20) Remarks. Three species of Tentorium are presently recognized (van Soest et al. 2012). T. aff. semisuberites differs from Tentorium papillatum ( Kirkpatrick, 1908) in having only one (or possibly a few) rather than numerous papillae. T. aff. semisuberites differs from T. levantinum Ilan, Gugel, Galil, & Janussen, 2003 which has the form of a pyramid rather than a hemisphere or cylinder. Tentorium aff. semisuberites cannot be differentiated from T. semisuberites based on most characters ( T. semisuberites here refers to North Atlantic populations). Both have a columnar or globular growth form, the texture of both is rough on top but smooth on the sides; both have one osculum although larger specimens in Norway may have 2–3 oscula; both have ostia restricted to the top; both may be of similar size (typically 3.5 mm high) although some specimens in the western Atlantic may be 1.5 cm high. Both have a fence of fusiform tylostyles in the ectosome. These range from 120 to 510 µm in length in T. aff. semisuberites and 270 to 670 µm in T. semisuberites . The principle fusiform subtylostyles form tracts running the length of the sponge. They range from 530 to 1050 µm in T. aff. semisuberites , and 950 to 2400 µm in T. semisuberites . This 2 ½ fold difference among the principle tylostyles is large; however, Plotkin & Janussen (2008) measured seven specimens and the maximum length of the principle tylostyle ranged from 920 to 1482 µm

Conclusions. The significant differences in maximum sizes of the principle tylostyles may indicate genetic differences or, alternatively, may be a reflection of significant differences in the height of the sponges and hence in length of the spicule tracts. Tentorium semisuberites has also been reported from several locations in the Antarctic (Boury-Esnault & van Beveren 1982; Plotkin & Janussen 2008). The absence of records between the Antarctic and the Azores suggests that T. semisuberites may be a candidate for bipolar distribution. Our report of T. aff. semisuberites from the cold temperate NE Pacific may reflect discontinuous distribution, or inadequate sampling in the Bering Sea and adjacent arctic waters. DNA bar coding might help resolve the relationships among these populations. Until then we have elected to refer to our material as T. aff. semisuberites .

Geographic distribution. T. aff. semisuberites : southern BC; T. semisuberites : Northern Hemisphere: Atlantic Arctic, N. Atlantic south to Azores. Although recorded in western Greenland, the Gulf of St. Lawrence and off Nova Scotia ( Lambe 1896), we could find no records for the Canadian Arctic or the Bering Sea.

T. cf. semisuberites : Southern Hemisphere: South Indian Ocean: Kerguelen I, South Atlantic: Inaccessible I, South Georgia, Antarctic: Western Ross Sea ( Plotkin & Janussen 2008).

Bathymetric range. T. aff. semisuberites 18–24 m (here-in); T. semisuberites : 26–3193 m depth ( Barthel & Tendal 1993).

Ecology. Where have tendrils been recorded? A sponge with a tendril was first reported in British Columbia by Lamb & Hanby (2005). It has not been seen since by these authors (pers. comm.). On Feb. 16, 2012 one of the present authors (N. McDaniel) found two sponges each with a long tendril ( Fig. 15 C). These were collected (KML 1300=T1, and KML 1301=T2). Mar. 6, 2012 two more sponges with tendrils (T3 & T4) were found at the same location. These were left in situ. The same two sponges, KML 1342, Sakinaw Rock, Sechelt Inlet (BC) (49° 34.075′N, 123° 48.238′W), 24 m depth, Dec. 11, 2012, coll. N. McDaniel; KML 1343, Sakinaw Rock, Sechelt Inlet (BC) (49° 34.075′N, 123° 48.238′W), 24 m depth, Dec. 11, 2012; coll. N. McDaniel, were inspected on Apr. 12, 2012. On each the tendril was gone and its location on the sponge was occupied by a single osculum. These sponges and five others were found again May 10, 2012 and Sept. 27, 2012. Two more sponges were found with short (2.5 cm) tendrils. These were observed two months earlier than in the previous year which suggests to us that these were in an early growth stage of the tendrils. The location and form of the spheres on the end of the tendril in KML 1343 suggests that they are propagules.

The only published reference we could find to T. semsuberites tendrils in other geographic regions was by Koltun (1966). He reported that sometimes the sponge becomes greatly stretched out into a thin stalk with a length of 20 cm. The specimen shown in his Figure 12 , plate XXXI looks identical in size and form to ours. However, Koltun regarded this form as an aberration. Alexander Plotkin found several sponges with long threads in the Russian Arctic which he initially identified as aberrant morphs of Tentorium semisuberites (pers. comm. to N. McDaniel). Barthel & Tendal (1993) observed what they called buds emanating from the base of some specimens. The relationship of these buds to those in the tendrils at the top of our sponges is unclear.

Battershill & Bergquist (1990) described asexual reproduction in Polymastia granulosa which showed some similarities to what we are observing here. A portion of the sponge pinches off and subsequently becomes much elongated and thread-like (6 cm). It then subdivides into a number of bead-like propagules which subsequently disperse by crawling away. In T. aff. semisuberites the tendril elongates while it is still attached to the papilla and incipient osculum of the sponge. We suggest that the tendrils can achieve such great length because the sponge continues to grow in the region of the papilla-tendril interface. At some point the tendril contents form a discontinuous series of beads as shown in Fig. 15 D. These appear similar to the beads described by Battershill & Bergquist (1990). We surmise that these are comparable to the propagules which these authors described as separating and crawling away for short distances. So one function of the tendril could be to disperse the propagules. Tentorium aff. semisuberites may occur on both hard and soft substrates. In the latter situation the sponge is described as having roots or alternatively of forming a broad basal plate, sometimes accompanied by agglutinating foraminiferans or spicules ( Barthel & Tendal 1993). We speculate that the tendril may serve as moorage maintaining each propagule at the sediment or rock surface while it becomes stabilized with roots or a broad basal plate. There is no direct evidence to indicate whether the tendril stage sponge itself resulted from sexual or asexual reproduction. We hope to make additional observations to support or refute our speculations in the coming years.

Figures

FIGURE 12. Sphaerotylus raphidophora n. sp. A, whole specimen preserved in alcohol, scale bar 1 cm; B, section showing tracts of megascleres radiating out to ectosome with protruding exotyles, scale bar 2 mm; C, exotyles showing expanded and stylote end, scale bar 100 µm; D, detail of expanded end, scale bar 20 µm.

FIGURE 15. Tentorium aff. s emisuberites (Schmidt, 1870). A, KML 1341 expanded, scale bar approx. 1 mm; B, KML 1341 contracted, scale bar 1 mm; C, KML 1301. sponge with tendril, scale bar 1 cm; D, another tendril sponge, scale bar 1 cm; inset portion of tendril with possible propagules, scale bar 1 mm; E, KML 1341 cross section, scale bar 1 mm; F, KML 1341 longitudinal section, scale bar 0.5 mm; G, KML 1341 large subtylostyle, scale bar 100 µm; H, KML 1341 large subtylostyle head, scale bar 10 µm; I, KML 1341 small tylostyle, scale bar 20 µm; J, KML 1341 small tylostyle head, scale bar 5 µm.