Chondraster grandis Verrill 1878

Chondraster grandis (Verrill 1878)

Porania grandis Verrill 1878: 371; 1882: 218; 1884: 652; 1885: 542 (pt.), pl. 15, fig. 44, pl. 16, fig. 44a (non figs 45, 45a= Porania pulvillus insignis)

(possible synonym) Tylaster willei Danielssen & Koren 1881: 186; 1884: 64; Ludwig 1900: 459; Ostergren 1901: 252; Grieg 1907: 32; Djakonov 1933: 44; 1950: 60 (1968: 51); A.M. Clark 1993: 238.

? Marginaster fimbriatus Sladen 1889: 365, pl. 58, figs. 4–6.

? Cheilaster fimbriatus Bell 1893: 81

Porania (Chondraster) grandis Verrill 1895: 137

Culcita borealis (pt.) Farran 1913: 15 (st. SR 483) [Non-C. borealis Süssbach & Breckner 1911]

Chondraster grandis A.M. Clark 1984: 27, figs. 4A, B, 5A, 6A, B, 7d; Harvey et al. 1988: 163; Clark & Downey 1992: 203.

Occurrence. Off Cape Cod (c. 42º) S to SE of Cape May(c. 38º), Lydonia Canyon (south side of George’s Bank), Baltimore Canyon, SE of Cape Mayin the NW Atlantic. Bear Seamount.

Lousy Bank, SW of the Faeroe Islands, Rockall Trough, Porcupine Seabight, and the Wyville Thomson Ridge south to the southern Bay of Biscay (c. 44ºN, 4ºW). 300–2490 m

Other Notes: This species has been observed in situ in several Northeast Atlantic localities by Remotely Operated Vehicles deployed by the Okeanos Explorer (pers. observations). Video observations of this species are recorded from Heezen, Hydrographer, and Nygren canyons where it has been observed on soft-sediment covered substrates in conjunction with octocorals and encrusting colonial invertebrates. It displays a purple/pink-white color in life.

Synonymy of C. grandis with Tylaster willei ? Tylaster willei Danielssen and Koren 1881 has been seldom recorded since its original description, and in spite of its occurrence in the Norwegian Sea and adjacent regions it is conspicuously absent from Clark and Downey’s (1992) comprehensive monograph of Atlantic asteroids. Subsequent accounts [e.g., Djakonov 1950 (1968)] have done little to elaborate on the poorly understood description of this species.

A review of the original description and comparison with further specimens of Chondraster grandis suggests it is consistent with the original description and figures as illustrated by Danielssen and Koren (1881) with several characters shared between C. grandis and T. willei. This includes the poorly decalcified abactinal surface, the distinct rows of actinal intermediate plates and tissue gaps between actinal plate rows, the fine spination present on the curved actinal series and a similar number of furrow spines present in each. Danielssen and Koren (1881) describe 3 adambulacral spines for a specimen with R=4.0 cm. A comparably sized specimen (USNM E30694) shows variable furrow spine number (2 or 3 furrow spines). It is also possible that Danielssen and Koren may have mistaken the subambulacral spines, of which there are three, for the furrow spines. Character differences between Chondraster and Tylaster summarized by A.M. Clark (1984) such as the fine spinules on the “dorsal body wall” are present on the surface of Chondraster, but below the epidermis. It is possible that T. willei may show damage to the body wall. Fine spinelets on the actinal surface are also present in both taxa. Further specimens, including the type will need to be studied in order to make a conclusive synonymy. In that event, Tylaster Danielssen and Koren 1881 would be the senior name for Chondraster Verrill 1895. For now, we retain Chondraster pending further examination of type specimens and possible suppression of the seldom used T. willei.

Material examined. USNM E30694 Lydonia Canyon, North Atlantic 40°21’49”N 67°39’44”W, 692 m, Coll. BLM submersible Alvin. (1 dry spec. R=5.6, r=3.2); USNM E50308 NE of Virginia Beach, 36°59’42”N 74°33’30W to 36°57’ 48”N 74°34’18”W, 649–864 m, coll. R/V Gilliss (2 dry specs. R=5.1, r=3.3; R=5.8, r=4.8); USNM E50540 Baltimore Canyon, 38°9’20”N 73°50’29”W, 621 m, Coll. DSR/V Alvin (1 dry spec. R=7.9, r=4.2); USNM 1016057 Bear Seamount, 39.94139, -67.38908, 1132–1888 m, coll. R/V Delaware II; USNM 1016073 Bear Seamount 39.93442, -67.39419, 1111–1541 m, Coll. R/V Delaware II.