Acanella robusta Thomson & Henderson, 1906

France, Scott C., 2017, A taxonomic review of the genus Acanella (Cnidaria: Octocorallia: Isididae) in the North Atlantic Ocean, with descriptions of two new species, Zootaxa 4323 (3), pp. 359-390 : 377

Acanella robusta Thomson & Henderson, 1906

Figure 11

Acanella robusta Thomson & Henderson, 1906: 33 ; Kükenthal, 1919: 577.

Type: Bay of Bengal , Station 325, 18° 18’ N, 93° 25’ E. 843 fathoms depth. Deposited in the Indian Museum, Calcutta.

For description see: Thomson & Henderson 1906

Remarks: We found two specimens with Haplotype H and their morphology corresponds to A. robusta ( Figure 11 ). They have prominently tuberculated sclerites, which give the sclerites a textured appearance that is visible to the naked eye, and small rods in the coenenchyme. A. robusta also differs from A. rigida by its large squat base (2 mm) and large, obliquely arranged sclerites that do not reach the whole length of the polyp, as they do in A. rigida . A. robusta is found deeper than A. rigida (1019̄ 1390 m; Figure 3 ).

Distribution: Our collection has expanded the known locations of A. rigida from the Andaman Sea and Bay of Bengal off the coast of Myanmar ( Burma) to the Bismark Sea off the coast of Papua New Guinea. The known depth range is expanded to 1019̄ 1542 m.

Figures

FIGURE 3. Box and whisker plot depicting the depth range of the 8 different Acanella Haplotypes (A-H) among the 97 samples sequenced for this study; where n = 1 the line connects depth extremes of the trawl that collected the sample. The Haplotypes are arranged in order of decreasing depth and divided by collection location (Haplotype A was collected from both the Atlantic and Pacific). The dashed line demarcates the 200 m isobath, a conventional limit for the upper depth of the deepsea (200 m).

FIGURE 11. SEM images of Acanella robusta (Haplotype H, PNG 1161). A) Tentacle sclerites. B) Coenenchyme sclerites. C) Polyp body sclerites.