Sibogagorgia dennisgordoni, JUAN ARMANDO SÁNCHEZ, 2005

JUAN ARMANDO SÁNCHEZ, 2005, Systematics of the bubblegum corals (Cnidaria: Octocorallia: Paragorgiidae) with description of new species from New Zealand and the Eastern Pacific, Zootaxa 1014, pp. 1-72 : 64-67

Sibogagorgia dennisgordoni sp. nov.

( Figs. 44–46 )

Material examined. Holotype: NIWA 3328, H­848, J237, Z8882, 37°01’S – 176°43.1’E, “Jasons Hill”, 976–1129 m, August 1997 (col. J. Wills, FV Margret Phillipa 1024, bottom trawl).

Paratype: NIWA 3329, P­1405, J246, Z9228, 36° 41.7S –176° 27.6E, western Bay of Plenty slope, 820 m, 17 August 1998 (col. J. Wills, FV Margret Phillipa 1124/70, bottom trawl).

Diagnostic characters. Cortex surface sclerites mostly 6­ and 8­radiates with grooved and irregular sub­radial ornamentation ( Figs. 45 A–C, 46A–C). Medulla sclerites slim, long, bare, straight spindles, with club like tips, up to 0.4 mm in length ( Figs. 45 E, 46E).

Description. Branched colonies up to 41 cm in height (holotype), terminal branches 5–8 mm in diameter ( Fig. 44 ). Cortex white to pale yellow. All sclerites colourless. Surface cortex with radiate sclerites (mostly 6­ and 8­radiates) with grooved and irregular sub­radial ornamentation ( Figs. 45 A–C, 46A–C). Surface sclerites up to 0.077 mm long averaging between 0.06–0.07 (0.004 SD, n=10, NIWA 3328; 0.005 SD, n=10, NIWA 3329). Surface radiates between 1.4–1.5 times longer than wider, averaging 0.04 mm in width (0.003 SD, n=10, NIWA 3328; 0.002 SD, n=10, NIWA 3329). Other intermediate forms between radiate and spindle present in the boundary layer ( Figs. 45 –46 D). Medulla with slim, long, bare, straight spindles, with club like tips, up to 0.4 mm in length ( Fig. 45– 46 F).

Morphological variation. The irregular nature of the ornamentation of the surface radiates makes this character very variable. Nonetheless, all the characters are consistent in the two available specimens.

Distribution. Only known from the volcanic Kermadec Ridge, NE of the Bay of Plenty, New Zealand, 820–1129 m.

Species comparisons. The diagnostic surface radiates of S. dennisgordoni sp. nov. are so derived compared to those in other Sibogagorgia species that they more resemble those of some Paragorgia species. The other Sibogagorgia species do not have 6­radiate forms. Medullar sclerites, the other diagnostic character, are also quite modified, being more slen­ der than in the other species. According to this character, S. dennisgordoni is closely related to S. tautahi because both species have bare spindles with only ornaments at the sclerite tip but S. tautahi has shorter and fatter forms.

Etymology: The species is named in honour of Dr. Dennis Gordon, who has made outstanding contributions to marine diversity and who introduced me to the fascinating octocoral fauna of New Zealand.

Figures

FIGURE 44. Sibogagorgia dennisgordoni sp. nov., holotype (NIWA 3328) (calliper open at 20 mm).

FIGURE 45. Sibogagorgia dennisgordoni sp. nov., holotype (NIWA 3328): A – C, radiates from the surface (scales 10 m) (A – B are stereo pairs); D, intermediate sclerites from the subsurface / medulla (scales 10 m); E, sclerites from the medulla (scales 100 m).

FIGURE 46. Sibogagorgia dennisgordoni sp. nov., paratype (NIWA 3329): A­C, Radiates from the surface (scales 10 m) (A­B are stereo pairs); D, Intermediate sclerites from the subsurface / medulla (scales 10 m); E, Sclerites from the medulla (scales 100 m).