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Comprehensive Description

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Description

"Adelascopora secunda sp. nov. (Fig. 5E, F)

 

Material

 

Holotype : BMNH 1987.9.20.19, "Discovery" stn. 1952, 2.1.1937, 367 - 383 m.

 

Description

 

Colony erect, bilaminate, developing flat, flabellate, dichotomously branching fronds ; without chitinous nodes. Holotype material up to 65 mm high, broadening distally to a maximum width of 7 mm ; distance between dichotomies about 10 mm. Autozooids rounded hexagonal, with distal and proximal walls straight ; convex, separated by distinct grooves. Primary orifice wider than long, D-shaped ; mid-distal portion with fine denticulation, proximal edge straight, or very slightly con­cave, with scarcely discernible lip thickened on each side to form minute condylar processes. Frontal wall thinly calcified, hyaline, with numerous small, closely spa­ced, round pseudopores ; ascopore reniform, small, scarcely two or three times the size of the frontal pores, with only a lightly thickened edge, situated almost exactly halfway along length of autozooid. Vertical walls with few, large septula, each with numerous pores. Colony margins and axes of dichotomies edged with large, blind kenozooids. Ovicells not developed in present material.

 

Measurements, means and standard deviations of 20 values, mm : Autozooid length 1.29 ± 0.11 Orifice length 0.18 ± <0.01 Autozooid width 0.57 ± 0.09 Orifice width 0.25 ± 0.01

 

Discussion

 

Specimens of this species were collected from "Discovery" stns. 1952 (South Shetlands) and 190 (Palmer Archipelago). It is distinguished from A. divaricata by its colony form, those of the latter being narrowly cylindrical or flattened, with distinct nodes consisting of cylindrical, chitinous tubes. The autozooids are rather larger than those of A. divaricata, but are otherwise very similar. The lateral sep­tula of A. secunda (Fig. 5F) are proportionately larger than those of A. divaricata (Fig. 5D), with three or four times as many pores. However, apart from this, and their very different colony form, and lacking any information on the ovicells of A. secunda, it is difficult to indicate any further firm distinctions between the two species." (Hayward & Thorpe, 1988b:293-5)

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Creative Commons Attribution Non Commercial 3.0 (CC BY-NC 3.0)

© National Museum of Natural History, Smithsonian Institution

Source: Antarctic Invertebrates Website (NMNH)

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