Pergamaster incertus (Bell, 1908)

Mah, Christopher L., 2011, Taxonomy of high-latitude Goniasteridae (Subantarctic & Antarctic): one new genus, and three new species with an overview and key to taxa, Zootaxa 2759, pp. 1-48 : 34-37

Pergamaster incertus (Bell, 1908)

( Figures 14 A–F)

Bell, 1908: 9; Fisher, 1940: 121; A.M. Clark, 1962: 22, 23; Bernasconi, 1963: 24 (as P. incertus ) Fisher, 1940: 122; A.M. Clark, 1962: 22; Bernasconi, 1963: 24. (as P. synaptorus ). Mein, 1992: 245 (as P. intercus )

Synonymy of P. synaptorus Fisher, 1940 . Character overlap between examined specimens suggests that P. synaptorus Fisher 1940 is a synonym of Pergamaster incertus (Bell, 1908) . Fisher (1940) distinguished P. synaptorus from P. in c er t u s by only one character, the distalmost five to seven superomarginals abutted over the midline on the arm. One specimen (USNM E13414) displayed the distalmost two to three superomarginals directly abutting, suggesting that this is a variable character. Character overlap between the two species is also present. Fisher (1940) described P. synaptorus has having 13–14 superomarginals on each arm (11–12 in the smaller paratype). Relatively large sized P. i n c e r t u s (USNM 1081793 w/R=4.0 cm) display 13–14 superomarginals on each arm. Geographic distribution and overall size of specimens do not show any clear distinction between the two species. Specimens with the “ P. synaptorus morphology” (i.e., with the abutted superomarginals) are indicated below to facilitate future studies.

Comment on Prydz Bay specimens. Images of Pergamaster incertus provided by the Museum Victoria (T. Ohara, pers. comm., 2010) show intermediate morphology present on Prydz Bay specimens relative to the Weddell Quadrant (to the west) and Ross Quadrant (Ross Sea, to the east). Although specimens from Prydz Bay display characters such as bare actinal plates adjacent to adambulacrals and similarly shaped abactinal peripheral granules that place it within P. incertus , specimens from this locality also display characters more similar to P. triseriatus , such as the largely complete cover of actinal plates (other than those adjacent to the adambulacrals) with angular granules and relatively large abactinal peripheral granules and plates, suggesting morphological continuity across sampled populations of Pergamaster across its range.

Distribution. McMurdo Sound off Wilkes Land west to MacRobertson Land, Palmer Archipelago, Antarctic Peninsular region, South Shetland Islands, South Orkney Islands, Bellinghausen Sea, Bransfield Strait. Prydz Bay, Fram Bank. 176–1120m.

Material examined. USNM E13413. North of Joinville Island, off tip of Antarctic Peninsula. 62˚41’S, 54˚ 43’W, 210– 220m. Coll. USARP, R/V Eltanin. 15 March 1964 (1 dry spec. R=4.0 r=1.2), E13414. Antarctic Peninsula, Trinity Peninsula, between peninsula and James Ross Island. 63˚40.07’S, 57˚50.07’W. 662–1120 m. Coll. USARP, R/V Eltanin 5 Jan. 1963. (1 dry spec. R=4.2, r=1.8). USNM 1081793, Antarctic Peninsula, 62˚40’S, 54˚45’W to 62˚40’S, 64˚44’W, 265 m. coll. Univ. of Southern California. (2 dry spec. R=4.1, r=1.6, R=4.0, r=1.4). CASIZ 162498 Near King George Island 61°44.88’S, 58°1.54’W, 256– 295 m. Coll. R. Mooi & S. Lockhart aboard the PFS Polarstern 13 Feb 2002 (1 wet spec. R=5.7, r=2.4). CASIZ 163059 Near King George Island 61° 49.35’ S, 58° 35.12’W, 399– 321 m. Coll. R. Mooi & S. Lockhart aboard the PFS Polarstern 13 Feb 2002 (1 wet spec. R=3.1, r=1.6). CASIZ 169935 South Shetland Islands, Elephant Island 61° 12’ 36”S, 55° 7’ 48’ W 261.0 m. Coll. R. Mooi & S. Lockhart aboard R/V Yuzhmorgeologiya Coll. 15 Mar. 2003 (2 wet specs. R=2.5, r=1.1; R=2.2, r=1.0). CASIZ 167614 Off King George Island, South Shetland Islands 61°27’36” S, 57° 13’ 47.9” 361– 363 m. Coll. R. Mooi & S. Lockhart aboard R/V Yuzhmorgeologiya Coll. 1 April 2003 (1 wet spec. R=1.5, r=0.7). CASIZ 174606 Bransfield Strait, 62°28’47”, 55°13’47”, 220– 224 m. Coll. S. Lockhart aboard R/V Yuzhmorgeologiya Coll. 14 March 2006 (1 wet spec. R= 5.2, r=2.2), CASIZ 180704. Scotia Sea , South Orkney Islands, 60°25’47” S 46°25’12” W, 140–153.0 m. Coll. S. Lockhart and N. Wilson aboard R/V Yuzhmorgeologiya 0 9 Feb 2009 (IZ Acc# 73950) (1 wet spec. R=5,1, r=2.0). CASIZ 180705. Scotia Sea , South Orkney Islands, 60°25’12” S 45°55’12” W, 214– 438 m. Coll. S. Lockhart and N. Wilson aboard R/V Yuzhmorgeologiya 0 9 Feb 2009 (1 wet spec. R=6.1, r=2.3).

Unexamined specimens. MV F81293 Prydz Bay, Fram Bank, 67º 9’ 58” S, 70º 39 49 E, 290 m, Coll. RSV Aurora Australis ; MV F81369 Prydz Bay, central Prydz Channel, 67º 10 50 S, 72º 13 20 E, 546 m, Coll. RSV Aurora Australis ; MV F81464 Prydz Bay, central Prydz Channel, 67º 11 17 S, 72º 17 39 E, 544 m, Coll. RSV Aurora Australis ; MV F 122642 Prydz Bay, 67º 52’ 24” S, 77º 26’ 24”E, 387–390 m, Coll. MS Nella Dan; MV F 122657 North of Prydz Bay sta. 2, 67º 24’ 36” S, 74º 33 36 E, 460 m; MV F81448 Prydz Bay, Fram Bank, 67º 08’ 07” S, 70º 46 51 E, 362 m, Coll. RSV Aurora Australis ; MV F 122453 Prydz Bay, 66º 46’ 26” S, 72º 36’ 29” E, 546 m, Coll. RSV Aurora Australis ; MV F 122479 Prydz Bay, 66º 58’ 212” S, 74º 56’ 18” E, 383–384 m, Coll. RSV Aurora Australis ; MV F 122485 Prydz Bay, 66º 59’ 54” S, 75º 13’ 18” E, 373–375 m, Coll. RSV Aurora Australis ; MV F 122481 Prydz Bay, 66º 48’ 06” S, 73º 29’ 54” E, 696–732 m, Coll. RSV Aurora Australis ; MV F 122483 Prydz Bay, Fram Bank, 67º 26’ 32” S, 70º 20’ 14” E, Coll. RSV Aurora Australis.

P. synaptorus morphology. USNM E 13416, Joinville Island, north of Island off tip of Antarctic Peninsula. 62˚40’S, 54˚45’W, 265 m. Coll. USARP, R/V Eltanin, 15 March 1964. (1 dry spec. R=4.2, r=1.2). E13415, South Shetland Islands, NE of Clarence Island. 60˚49’S, 53˚28’W, 587– 589 m. Coll. USARP, R/V Eltanin 17 April 1964. (1 dry spec. R=2.5 r=1.1). USNM 1082731, Antarctic Peninsula. 62˚41’S, 54˚43’W, 210– 220 m. Coll. Univ. Southern California. (1 dry spec. R=2.5, r=1.1). CASIZ 162496 Antarctic Peninsular shelf. 62°34.63’S, 55°39.96’W, 157–167.2 m. Coll. R. Mooi & S. Lockhart aboard PFS Polarstern 21 Feb. 2002. (1 wet spec. R=5.1, r=2.3). CASIZ 175979 Bransfield Strait. 63.24°S, 59.78°W, 224– 249 m. Coll. S. Lockhart & V. Smith aboard R/V Yuzhmorgeologiya, 20 Feb. 2006 (1 wet spec. R=5.5, r=2.5). CASIZ 175993 Bransfield Strait. 62° 37' 11.9” S, 56° 37' 11.9W, 227.0 m. Coll. S. Lockhart & V. Smith aboard R/V Yuzhmorgeologiya 19 Dec. 2007. (R=5.7, r=2.2), CASIZ 108734, South Orkney Islands, Scotia Sea , 60° 25' 12"S, 45° 55' 12"W, 214– 438 m. Coll. S. Lockhart & N. Wilson aboard R/V Yuzhmorgeologiya 10 Feb. 2009 (1 wet spec. R=5.7, r=2.2); CASIZ 108738, South Orkney Islands, Scotia Sea , 60º45’35.9’S, 43º25’12” W, 319– 330 m. Coll. S. Lockhart & N. Wilson aboard R/V Yuzhmorgeologiya 14 Feb. 2009 (1 wet spec. R=3.9, r=1.5).

Description. Body surface flattened, stellate in shape, arms triangular, elongate ( Fig. 14 A–C). Interradial arcs weakly curved to linear ( Fig. 1 A). R/r= 2.1 to 2.6.

Abactinal plates flattened to weakly convex, smooth, with no accessories present on plate surface. Each plate irregularly round to rounded quadrate to polygonal in outline, variable in size ( Fig. 14 B, C). Largest plates proximal on disk with smaller plates distally located adjacent to contact with superomarginal plate series. Generally only one complete series of abactinal plates to terminal plate on arm with adjacent series ending near base of arm. Carinal series variable in outline, becoming more distinct distally along arm becoming smaller, narrower adjacent to armtip. Granules, 5–30, with variable size and shape, outline shape ranges from quadrate granular to smaller oblong bean-like, forming discrete peripheral border around each abactinal plate surface. Granules relatively small, making up approximately 10–15% of total distance of the surface on each carinal plate. Central actinal plate surface (within granular periphery) is bare and smooth with no accessories. Abactinal plates, granules, and superomarginal plates all forming essentially flush surface. Fasciolar grooves shallow to absent. Madreporite polygonal, with relatively shallow sulci, flanked by five abactinal plates. Papulae present over radial regions, absent from interradii.

Marginal plate outline varies between proximal interradial regions and distal regions on arms becoming more rounded-quadrate on arms versus more quadrate proximally becoming smaller and more numous distally adjacent to the terminal. Superomarginal and inferomarginals are slightly offset, forming zigzag pattern when viewed laterally ( Fig. 14 E). Proximal interradial plates more elongate, with narrower length relative to those more distal. Superomarginals, 25–28, inferomarginals, 30–38 (both at R=~3.5) from armtip to armtip, rounded-quadrate in outline, forming rounded dorsolateral edge. Marginal plate surface flat to weakly convex and smooth, lacking any ornamentation or surface accessories. Marginal plates granules, 18–40, forming distinct periphery in regular series. Granules quadrate and rectangular/elongate in outline similar to, but smaller than, those forming periphery around abactinal plates. On at least one specimen (USNM 1082731) only 4 of 5 arms possess superomarginal plates abutting over midline with the 5th arm displaying carinal plates extending to terminus. Others, such as USNM 1081793, display only superomarginals adjacent to the terminals abutting with carinals extending to the terminal plate on remaining arms. On smaller specimens (USNM 1082731, R= 2.5 cm) superomarginal plates abut over midline, they do so approximately 6–8 plates away from the terminus.

Terminal plate round, smooth, convex, abutting against two superomarginals ( Fig. 14 F).

Actinal surface concave with smooth/bare actinal plates proximally. Where granular cover is present, it is densely distributed distally on plates adjacent to contact between actinal and inferomarginal plate series. Granules vary in shape but are angular to flattened to irregular in shape. Fasciolar groove shallow. Actinal plates each with granular periphery composed of 8–16 individual granules.

Furrow spines two to three, blunt, thick and oval in cross-section (e.g., Fig. 14 D). Subambulacral spines two, one short, pointed, triangular to quadrate in cross-section; the other elongate, blunt, with similar thickness but 25– 50% of furrow spine length becoming similar in length to furrow distally near armtip, round-ovaloid in cross-section. A bare space generally occurs between the furrow and subambulacral spines. Adambulacral granules two to six, similar flattened or pointed with angular shape, triangular to polygonal in outline, similar in overall appearance to those on actinal plates.

Furrow spines on oral plate, two, Oral spines projecting into mouth, one per plate (two project into mouth), thick, blunt, round to oval in cross-section. Oral spines similar in thickness to furrow spines. Spines on oral plates, two on each plate surface, with each set paired off. Approximately two to three granules, angular to polygonal in outline present on each oral plate distally relative to the oral spines.

Pedicellariae not observed.

Figures

FIGURE 1. Ceramaster patagonicus australis. USNM 1121579. A. Abactinal surface. B. Close-up of abactinal plates. C. Close-up of armtip showing superomarginal plate series. D. Actinal surface. E. Close-up of actinal surface showing mouth and furrow spination. Scale Bar = 0.5 cm.

FIGURE 14. Pergamaster incertus (USNM 1081793) A. Abactinal surface. B. (inset) Close up of abactinal plates and madreporite. C. Abactinal view of arm showing superomarginals not abutted. D. Actinal surface and furrow spines. E. Lateral view of marginal plate series. USNM E 13415 (ex. P. synaptorus) F. Abactinal arm showing abutted superomarginals over midline. Scale Bar = 0.5 cm.