Errinopora undulata 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 : 14-16

Errinopora undulata Lindner & Cairns sp. n. Figs 5C, F7 A–J

Errinopora undulata Lindner, 2005: 120-122, figs 4.6B, 4.19 (unpublished name).

Type material.

Holotype: Vessel and collector unknown, Amukta Pass, 350-500 m,1 dry female colony 12 cm tall, USNM 1123527 (Fig. 5C). Paratypes: Vessel and collector unknown, Amukta Pass, 356-640 m, 1996, 1 dry female colony, USNM 1123528; south of Semisopochnoi Island, 366 m, 1 dry female colony, USNM 88371. Type locality. Aleutian Islands: Amukta Pass, 350-500 m.

Etymology.

The specific name undulata (from the Latin undulatus, meaning wavy) refers to the sinusoidal margin of the lamellate colonies.

Material examined.

Types.

Description.

Colonies lamellate, but wavy in construction resulting in a continuous, thin (1.7-2.0 mm thick), sinusoidal distal edge. Largest colony (USNM 1123528, Fig. 5F) 13 cm tall and 15 cm wide, with a massive basal branch 4.5 × 2.5 cm in diameter; holotype (Fig. 5C) smaller and less intact, measuring 12 cm tall and 11 cm wide, with a basal branch 3.5 × 2.8 cm in diameter. Parasitic spionid worm tubes found in only one colony (USNM 1123528). Coenosteum quite porous, consisting of a reticulum of narrow spiny strips separated by even wider slits, the spines being 10-15 µm in diameter. Coenosteum orange.

Dactylopore spines occur equally on both branch faces, but less abundant toward corallum base. Most dactylopores clustered around isolated gastropores in pseudocyclosystems, 3-5 spines surrounding one pore (Fig. 7B). Pseudocyclosystems most common toward base of colony but also occur frequently on more distal parts of corallum where they are interspersed with short, transverse rows of dactylopore spines that border the distal margins of one or more gastropores, their dactylotomes facing upward (abcauline) toward the gastropore; compound dactylopore spines absent. Dactylopore spines fairly short (rarely taller than 0.25 mm), 0.40-0.45 mm in width, and thin walled, the majority of width being the dactylotome; dactylopore spine walls longitudinally ridged. Dactylostyles robust (Fig. 7 I–J), up to 0.12 mm in width, consisting of cylindrical elements up to 72 µm in length and 15 µm in diameter. Secondary flush dactylopores common, about 75 µm in diameter.

Gastropores circular, flush with coenosteum, and 0.3-0.45 mm in diameter; secondary gastropores about 0.19 mm in diameter. Gastropore tubes short and lack a ring palisade. Gastrostyles lanceolate, the figured style (Fig. 7G) 0.54 mm in height and 0.29 mm in diameter, covered with longitudinal anastomosing spiny ridges.

Female ampullae (Fig. 7 A–B) irregularly-shaped, flattened hemispheres up to 1.6 mm in diameter. Efferent pores not observed. Male ampullae unknown.

Remark.

. Errinopora undulata is quite similar to the lamellate form of Errinopora nanneca , but differs in a number of points, one being its colony form, which is a continuous wavy sheet of corallum, whereas that of Errinopora nanneca is more like a series of smaller dissected flat blades of a larger plate. Errinopora undulata also has shorter (0.25 vs 0.4 mm) and thin-walled (vs thick-walled) dactylopore spines, and larger gastropores (0.45 mm vs 0.20 mm in diameter) (see Dichotomous Key and Table 1).Of the 247 known stylasterid species ( Appeltans et al. 2011: WoRMS database: www.marinespecies.org) only five have adopted a lamellate corallum shape, four of these occurring in the Aleutian Islands ( Cyclohelia lamellata , Stylaster repandus , Errinopora nanneca , and Errinopora undulata ), the fourth being the Hawaiian Distichopora anceps Cairns, 1978.

Distribution.

Known only from the Aleutian Islands: Amukta Pass and south of Semisopochnoi Island; 350-640 m (unconfirmed).