Errinopora fisheri Lindner & Cairns

Cairns, Stephen D. & Lindner, Alberto, 2011, A Revision of the Stylasteridae (Cnidaria, Hydrozoa, Filifera) from Alaska and Adjacent Waters, ZooKeys 158, pp. 1-88 : 12-14

Errinopora fisheri Lindner & Cairns sp. n. Figs 5A6 A–K

Errinopora fisheri Lindner, 2005: 100-102, figs 4.6A, 4.14 (unpublished name).

Type material.

Holotype: Pacific Knight 204, a dry female colony, USNM 1123526 (Fig. 5A). Paratype: Sea Storm 36, 53°05'45"N, 171°41'56"E, 458 m, 1 branch, USNM 1157073. Type locality. 53°06'N, 171°42'E (off Attu Island, Aleutian Islands), 455 m, 31 Jul 1994.

Etymology.

Named in honor of Walter K. Fisher, who wrote the original revision of the Aleutian Island stylasterids ( Fisher 1938) and described the genus Errinopora (Fisher, 1931).

Material examined.

Holotype.

Description.

Holotype (Fig. 5A) uniplanar with a secondary flabellum at mid-height, 9 cm in height and 6.5 cm in width, with a basal branch diameter of 10 × 7.5 mm. Branches circular to slightly elliptical in cross section and irregularly dichotomous, small-diameter branches often diverging from larger main branches; branch anastomosis absent. Coenosteum reticulate-granular in texture, the strips being 80-90 µm in width and covered with small granules 5-15 µm in diameter; strips bordered by slits 40-45 µm wide. Coenosteum light orange.

Dactylopore spines favor one face of corallum over the other, arranged in abcauline, crescent-shaped terraces flanking one or two gastropores (Fig. 6A-D). Terraces sometimes almost completely surround a gastropore (Fig. 6C-D), resembling a cyclosystem of 1.5 mm diameter with an adcauline diastema, much as in Stylaster , but isolated dactylopore spines also fairly common, especially near base of colony. Dactylopore terraces quite thin (0.35 mm) and up to 1.5 mm in height, and, although laterally fused, the individuality of each dactylopore spine is subsumed into the more continuous terrace structure; compound dactylopore spines absent; exterior surface of spines longitudinally ridged. Terraces often horizontally oriented on branches, and slightly flared around gastropore(s). Dactylotomes not slit-shaped as in most other Errinopora , but instead small elliptical pores about 0.27 mm long and 0.15 mm in width occurring only near tips of spine structure; dactylotomes always directed toward a gastropore. Dactylostyles small, about 50 µm in width, having stubby elements up to 25 µm in length and 10-15 µm in diameter. Secondary dactylopores absent.

Gastropores circular, flush with coenosteum, 0.3-0.5 mm in diameter, being fairly consistent in size; gastropores isolated, not arranged in rows; secondary gastropores absent. Gastropore tube cylindrical, but with a slight medial constriction; often a ring palisade is present, the elements 50 µm tall and 15-25 µm in diameter. Gastrostyle squat, an illustrated one being 0.33 mm tall and 0.29 mm in diameter (Fig. 6I). Gastrostyles covered with longitudinal anastomosing ridges as consistent with the genus. Female ampullae (Fig. 6D) hemispherical but often irregular in shape due to protrud ing dactylopore spines. Female ampullae 1.0-1.2 mm in diameter; efferent pores not observed. Male ampullae unknown.

Remarks.

Even though represented by only one specimen, Errinopora fisheri can be distinguished from other Alaskan congeners by the distinctively terraced arrangement of its dactylopore spines, its small elliptically-shaped dactylotomes, its squat gastrostyles, and its constricted gastropore tube with a ring palisade (see Dichotomou s Key and Table 1). Most of these features, however, are shared with Errinopora cestoporina , a species known only from Burdwood Bank and off Tierra del Fuego at 359-384 m. Errinopora cestoporina differs in having differently shaped ampullae, a different corallum color (white), small perforated mounds covering the coenosteum, and a differently shaped gastrostyle.

Distribution.

Known only from Aleutian Islands: off Attu Island; 455-458 m.