Stylaster elassotomus
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Ordo: Filifera
Familia: Stylasteridae
Genus: Stylaster
Name
Stylaster elassotomus Fisher, 1938 – Wikispecies link – Pensoft Profile
- Stylaster elassotomus Fisher, 1938: 499-500, pl. 41, fig. 3, pl. 42, figs 1–1c, pl. 49, fig. 1.—Boschma 1957[1]: 7.—Wing and Barnard 2004[2]: 11 (key), 28.—Heifetz et al. 2005[3]: 134, 137 (listed).—Stone and Shotwell 2007[4]: 108 (listed).—Jameison et al. 2007: 224 (listed).
Type material
Holotype: 1 dry male colony, and SEM stub 1507, USNM 43268 (Fig. 21C). The pale pink paratype 5 cm in length (USNM 86007) mentioned by Fisher is an unidentified Stylaster having little in common with the holotype. Type locality. Albatross 4781, 52°14'30"N, 174°13'E (off Agattu Island), 882 m.
Material examined
Types.
Description. Holotype (Fig. 21C) colony bushy, 5.5 cm tall and 4.5 cm wide, attached by a basal branch 6 mm in diameter. Branches do not anastomose and are circular in cross section. Coenosteum reticular-granular in texture, the strips 55–60 µm in width, separated by slits 10–14 µm wide; strips covered with small angular granules. Spionid worm tubes absent. Coenosteum white.
Cyclosystems circular to slightly elliptical, 1.0–1.2 mm in diameter, arranged exclusively on branch edges in an alternating fashion, most projecting perpendicular to branch. Gastropores circular and quite large (0.5–0.6 mm in diameter), occupying up to 55% of cyclosystem diameter (Fig. 25F). Gastropore tube cylindrical, curved, and long, such that gastrostyle tip is rarely seen when viewed from above (Fig. 25A). A delicate ring palisade (Fig. 25C–D) occurs near gastrostyle tip, composed of slender cylindrical elements up to 60 µm long and 25 µm in diameter. Gastrostyle slender (H:D = 4.4), the illustrated style 0.53 mm in height, occupying lower quarter of gastropore tube (Fig. 25A).
Dactylotomes 60–80 µm wide but very short as well as having short internal slits, thus contributing to the large size of the gastropore tube (Fig. 25F); dactylostyles inconspicuous. Range of dactylopores per cyclosystem 11–17 (n = 21, average = 14.40 (σ = 1.36), and mode = 15). Supernumerary dactylopores common (Fig. 25B), 70–100 µm in diameter. Pseudosepta same width as dactylotomes; diastemas rare.
Female ampullae unknown. Male ampullae (Fig. 25G) hemispherical, 0.5–0.6 mm in diameter.
Remarks
Despite access to a diverse stylasterid collection from the Aleutian Islands, no unequivocal additional specimens could be identified as Stylaster elassotomus, even the paratype of the species not considered to be conspecific. Its distinctive characteristics of having a highly curved gastropore tube, slender ring palisade elements, and a very large gastropore surrounded by very short dactylotomes and pseudosepta distinguish it from all other Alaskan species (see Table 2).
Distribution
Known only from type locality.
Taxon Treatment
- Cairns, S; Lindner, A; 2011: A Revision of the Stylasteridae (Cnidaria, Hydrozoa, Filifera) from Alaska and Adjacent Waters ZooKeys, 158: 1-88. doi
Other References
- ↑ Boschma H (1957) List of the described species of the order Stylasterina. Zoologische Verhandelingen 33: 1-72.
- ↑ Wing G, Barnard D (2004) A field guide to Alaskan Corals. NOAA Technical Memorandum NMFS-AFSC-146, NOAA, US Dept of Commerce, 67 pp.
- ↑ Heifetz J, Wing B, Stone R, Malecha P, Courtney D (2005) Corals of the Aleutian Islands. Fisheries Oceanography 14: 131-138. doi: 10.1111/j.1365-2419.2005.00371.x
- ↑ Stone R, Shotwell S (2007) State of deep coral ecosystems in the Alaskan region: Gulf of Alaska, Bering Sea and the Aleutian Islands. In: Hourigan TF et al. (Eds) The State of Deep Coral Ecosystems of the United States. NOAA Technical Memorandum CRCP-3, NOAA, Silver Spring, 65–108.
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