Polymastia pachymastia

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 : 24-28

Polymastia pachymastia de Laubenfels, 1932

Fig. 8 A–J

Polymastia pacifica of Green & Bakus 1994 Material examined. Holotype: USNM 22062, Point Lobos, Carmel, central California, (approx. 36º 31′N, 121º 57′W), littoral, Jul. 12, 1930, coll. M. W. de Laubenfels.

Other material: KML 1021, KML sta. 56/70, Wizard I., Barkley Sd., BC, (48º 51.6′N, 125º 09.4′W), 4–8 m depth, Mar. 20, 1970, coll. W.C. Austin; BMSC 429, KML sta. 3/72, Dixon I, Barkley Sd., BC, (48º 51.2′N, 125º 07.2′W), 9 m depth, Jul. 1972, coll. W.C. Austin; KML 1022, KML sta. 252/76, Mills Peninsula, Barkley Sd., BC, (48º 49′N, 125º 09.8′W), 12 m depth, Nov. 3, 1976, coll. W.C. Austin; KML 1023, KML sta.174/76, Houston Stewart Channel, Haida Gwaii, BC, (52º 09.5′N, 131º 05.6′W), 20–24 m depth, Aug. 3, 1976, coll. W.C. Austin; CASIZ 0 0 0 167, Garapata Canyon, Monterey County, CA., (approx. 36º 27′N, 121º 55′W), no depth or collection date, coll. D. Elvin/W. Lee; KML 1024, KML sta. 577/77, Beaver Pt., Saltspring I., BC, (48º 46.1′N, 123º 22.5′W), no depth, Jun. 23, 1977, coll. W.C. Austin; CMN off Amchitka, Alaska, (51º 19.3′N, 178º 55.0′W), no depth, Sept. 5, 1969, coll. unknown; CMN off Rifle Range Point, Amchitka, Alaska, no coordinates or depth, Sept. 4, 1969, coll. C. O’Clair; CMN St. Makarine Bay, Amchitka, Alaska, Sept. 17, 1969, coll. C. O’Clair; CMN off Amchitka, Alaska, (51º 25.4′N, 179º 16.5′E), no depth, Oct. 8, 1969, coll. C. O’Clair; RBCM 977-156-2, Hope I, BC, (50° 54.3′N, 129° 56.3′W), 24.4 m depth, Jul. 18, 1977, coll. P. Lambert; RBCM 980-340-2, Coal Hbr, Holberg Inlet, BC, (50° 35′N, 127° 34.6′W), less than 12 m depth, July 3, 1980, coll. P. Lambert; RBCM 980-342-4, Shapland Cover, BC, (50° 29.5′N, 127° 47.5′ W), less than 15 m depth, July 4, 1980, coll. P. Lambert; RBCM 999-213-8, Moresby I., Haida Gwaii, BC, (52° 8.45′N, 131° 8.07′W), 47.1–52.2 m depth, Jul. 18, 1999, coll. P. Lambert.

Field Images: Koskimo I., Quatsino Sd., BC, (approx. 50º 27′N, 127º 53′W), 20 m depth, Jul. 30, 1975, photo N. McDaniel; near Entrance I., Strait of Georgia, BC, (approx. 49º 12′N, 123º 48′W), no depth, Jul. 14, 1973, photo N. McDaniel; Raza Passage, Kinghorn I., BC, (approx. 50º 18′N, 125º 00′W), 25 m depth, Aug. 12, 1976, photo N. McDaniel; Vivian I., BC, (approx. 49º 50′N, 124º 42′W), no depth or date, photo N. McDaniel; Chrow Islands, Barkley Sd., BC, (approx. 48º 55′N, 125º 29′W), no depth or date, photo N. McDaniel; Discovery Passage, BC, (approx. 50º N, 125º 11′W), no depth or date, 4 photos, N. McDaniel.

Description. Macroscopic features. Form massive with digitate fistulae projecting up to 2 cm above main body of sponge (preserved). Basal diameter of fistulae 1–2 cm, but smaller diameters occur in smaller specimens. NE Pacific Polymastia pachymastia can reach up to a meter in diameter and 3 cm thickness based on specimens we have examined and/or photographed. Fistulae open and elongate ( Fig. 8 A) or contracted and closed ( Fig. 8 B). A single apical osculum on many fistulae. Ostia not observed. Fistulae soft with smooth surface, while main body tough, wood-like and coarsely hispid. Fistular colour ranging from white ( Fig. 8 A, B) to yellow ( Fig. 8 C, D), while main body consistently brown from adhering sediment or covered by coralline algae.

Microscopic features, Fig. 8 E. Ectosome of body forming cortical layer approximately 1.5 mm thick, continuous with ectosome of fistulae, where cortex thinner (0.5 to 1 mm thick). Cortex packed with tylostyles at right angles to surface, apices outward and forming palisade. Mesh of spicules tangential to surface in lower ectosome ( Fig. 8 E, portion visable mid-right). Large styles penetrate body surface, projecting> 1 mm, apices out. Within body large tylostyles interspersed with small tylostyles, while in fistulae small tylostyles occasionally forming brushes and fewer large tylostyles echinating fistular surface. Palisade of both intermediate and small spicules (tylostyles II and III), rather than only distinctly small tylostyles; large, thin styles penetrating the surface irregularly, extending past surface as far as 2 mm ( Fig. 8 E, top right). Fistulae macroscopically smooth, but microhispid with large tylostyles, apices out, extending up to 100 Μm beyond surface. Choanosome: skeleton composed of radiating, closely packed multispicular tracts of large spicules. Tylostyles II, together with styles I, form the ascending multispicular tracts in the choanosome ( Fig. 8 E, bottom), 200–800 Μm diameter ascending to, penetrating, and supporting cortical layer of ectosome. Smaller tylostyles ( Figs. 8 G, H, J) scattered among principal tracts.

Spicules. Spicule complement includes two size classes of styles and three classes of tylostyles. Styles I are sometimes very slightly subtylote. Styles II are very long, straight and thin and echinate the main sponge body; tylostyles I are short, stout, fusiform; some with subterminal heads, some polytylote and are abundant in cortex and choanosome; tylostyles II are long, fusiform, some with subterminal heads, some polytylote and are abundant and in same locations as tylostyles I; tylostyles III are small, thin straight, some with subterminal heads, and are abundant. Length and width ranges may overlap in Tylostyles I and II in some specimens and Tylostyles I and II may be just one highly variable spicule type. Table 5 lists spicule measurements from five specimens, and Table 6 lists the relative percentages of the three tylostyle types in the ectosome of four P. pachymastia specimens plus the USNM type specimen we examined.

Specimen Proportion Range

Tylostyle I Tylostyle II Tylostyle III Holotype 18–32% 5–21% 47–78% BC 1 16–30 % 6–16% 63–72% BC 2 13–51 % 3–10% 46–84% BC 3 27–43 % 2–11% 53–65% BC4 37–56% 5–7% 39–57% Total 13–56% 2–21% 39–84%

Tylostyles I: 143–380 Μm Tylostyles II; 450–750 Μm Tylostyles III: 55–173 Μm BC specimens were random samples from the south to central coast.

Remarks. De Laubenfels (1932) noted a relative scarcity of small tylostyles in the ectosome of the type specimen. This would set Polymastia pachymastia apart from other NE Pacific Polymastia ( P. kurilensis , P. pacifica , P. piscesae ). However, our re-examination of the type specimen from central California ( Table 5) indicated the ectosome had a palisade composed of 47% to 78% small tylostyles interspersed among the larger spicules. In four specimens from BC the small tylostyles (tylostyles III) are as abundant, or more abundant, than the long (type II) tylostyles in the ectosome (Table 3). Polymastia laganoides Lambe, 1893b (Table 3) is the only species recorded in the north Pacific that lacks a palisade of small tylostyles. Small tylostyles are present in the ectosome but are irregularly distributed. Polymastia laganoides has only a few wartlike fistulae ( Fig. 6 B).

De Laubenfels (1932) named P. pachymastia for its characteristic short, wide fistulae. Specimens we have examined may have shorter or longer fistulae, but the basal diameter is wide compared to other species recorded from the North Pacific, except for Polymastia affinis Thiele, 1898 ( Fig. 6 G). The bases of the fistulae are up to 1.1 cm in diameter in both species. The height of the fistulae may be not much greater than the width, and they form blunt cones ( Fig. 6 G, Fig. 8 B).

The two species differ as follows: style II is somewhat longer in P. affinis than in P. pachymastia while style I is 80% longer in P. pachymastia than in P. affinis . Also, P. affinis is recorded from 102–303 m depth ( Koltun 1966); while P. pachymastia occurs in intertidal and shallow (0–40 m) waters. Shallow water (13–16 m) specimens in Sagami Bay, Japan identified as P. affinis ( Tanita et al. 1989) are most likely another species based on the short (520–750 µm) large subtylostyles.

Conclusions. An absence or paucity of small tylostyles in a cortical palisade of P. pachymastia is not supported by the evidence in our study, and hence cannot be invoked to set off P. pachymastia from other North Pacific species. The form and size of the fistulae differ from other recorded North Pacific species of Polymastia except for P. affinis . Differences in style length and bathymetric distribution from P. affinis support maintaining P. polymastia as a separate species. P. pachymastia is easily distinguished visually from other Polymastia found within its range based on the large (1–2 cm) basal diameter of the fistulae.

Bathymetric range. Intertidal to 40 m depth; most common in the shallow subtidal,

Geographic distribution. Southern California to Aleutian I., Alaska ( USA).

Ecology. We frequently encountered Polymastia pachymastia in shallow water along the NE Pacific coast. It settles on hard substrates but can tolerate a moderate level of sediment deposition, possibly due to the oscula and ostia being located on raised fistulae. We found it on both horizontal and inclined surfaces and in current-swept or calm waters.

Figures

FIGURE 6. Multifistulate Polymastia spp. in the NW Pacific. Numbers, form and size of fistulae. Scale bar, 3 cm on all but C where scale bar 5 cm. A, P. kurilensis Koltun; B, P. laganoides Burton; C, P. fluegeli Lehnert et al.; D, large P. toporoki Koltun; E, small P. toporoki; F, P. affinis Thiele, fistulae contracted; G, P. affinis, fistulae expanded. A, D – G from Koltun 1966; B from Lambe 1895, courtesy Royal Society of Canada; C from Stone et al. 2011.

FIGURE 8. Polymastia pachymastia de Laubenfels, 1932. A, fistulae expanded and oscula open, scale bar approx. 1 cm; B, fistulae contracted and oscula closed, scale bar approx. 1 cm; C, yellow specimen, scale bar approx. 1 cm; D, large specimen, scale bar approx. 10 cm; E, SEM cross section showing palisade of small tylostyles in ectosome, and long styles extending beyond ectosome, scale bar 1 cm; F, style I, scale bar 500 µm; G, head of style I, scale bar 20 Μm; H, tylostyle I, scale bar 100 µm; I, tylostyle I head, scale bar 30 µm; J, tylostyle III, scale bar 300 µm; K, head and foot of tylostyle III, scale bar 100 Μm; L, tylostyle II, scale bar 50 Μm; M, head of tylostyle II, scale bar 10 Μm.

Tables

TABLE 6. Percent of Tylostyle Types in the Polymastia pachymastia de Laubenfels, 1932, Ectosome.

Spicule Type	Fig.	Length	Width
BMSC 429		Dixon Island, Barkley Sound
Styles I	8F, I	960–(1425)–2646	12.8–(26.8)–37.5
Styles II	none	2200–(3038)–3340 N=4	22.5–(23.9)–25.0
Tylostyles I	8G	143–(277)–380	5–(18.1)–25
Tylostyles II	8G	450–(582)–750	13.8–(29.5)–40
Tylostyles III	8H, J	55–(137.5)–172.5	1.5–(4.4)–7.5
RBCM 977-156-2		Hope Island, Bull Harbour
Styles I		700–(892)–1070	15.0–(18.7)–22.5
Styles II		2550–(3600)–4425	12.5(23.3)–28.8
Tylostyles I		180–(252)–390 N=50	10.0–(16.2)–25.0
Tylostyles II		320–(438)–690	12.5–(20.1)–40.0
Tylostyles III		125–(158)–188	3.8–(5.1)–8.8
RBCM 980-340-2		Holberg Inlet, Coal Harbour
Styles I		500–(784)–1090 N=50	15.0–(23.5)–41.3
Styles II		1250–(1533)–1875	22.5–(29.4)–41.0
Tylostyles I		200–(335)–390 N=50	7.5–(13.6)–20.0
Tylostyles II		350–(453)–620	10.0–(13.8)–18.3
Tylostyles III		118–(165)–215	2.8–(4.3)–5.0
RBCM 980-342-4		Shapland Cove
Styles I		720–(917)–1100	13.8–(18.2)–21.3
Styles II		1500–(2731)–3475	10.0–(16.1)–22.5
Tylostyles I		200–(268)–380	7.5–(15.1)–25.0
Tylostyles II		320–(499)–710 N=50	15.0–(23.7)–33.8
Tylostyles III		130–(174)–210	3.8–(4.8)–6.3
RBCM 999-213-8		Morseby Island, Rose Inlet
Styles I		790–(1137)–1440	13.8–(21.1)–27.5
Styles II		2125–(2263)–2400 N=2	10.0–(12.5)–15.0
Tylostyles I		200–(307)–410	11.3–(16.4)–21.8
Tylostyles II		420–(542)–650	16.3–(22.6)–30.5
Tylostyles III		90–(136)–183	3.0–(4.5)–5.5