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Artopilium undulatum Popofsky, 1913

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Benson, 1966 (partim.), p. 494-496; pl. 34, figs. 1-2, (not 3):

Lophocorys polyacantha Popofsky


Lophocorys polyacantha Popofsky, 1913, Deutsche SŘdpolar-Exped., vol. 14, pp. 400-401, text fig. 122.
?Artopilium undulatum Popofsky, 1913, op. cit., pp. 405-406, Pl. 36, figs. 4, 5.

Test with 3-5 joints that increase in breadth distally and are separated by broad constrictions without septal rings. Individual joints in most tests with rounded shoulders or at least broader proximally and nearly cylindrical distally.
Forms identical with Lophocorys polyacantha Popofsky and Artopilium undulatum Popofsky are included together because specimens corresponding to the latter are rare in the Gulf but are similar to the former in shape of joints and basic structure of the cephalis. The relationships between these two forms are not clear, and further taxonomic study of them is needed.

Tests corresponding to Artopilium undulatum Popofsky are generally smooth, have small, subequal, circular to irregular pores that are arranged subhexagonally either in approximate longitudinal or transverse rows, or both, and increase only slightly in size distally. The individual joints are more nearly campanulate in several tests, but in others their outline is the same as in the forms described above. The structures of the cephalis are the same except that the apical spine or horn is nearly vertical in some specimens.

Measurements; based on 14 specimens from stations 46, 60, 64, 81, 93, 106, and 151: maximum length of test 111-200 Ám, maximum breadth 74-117 Ám; length of cephalis 21-34 Ám, breadth 25-34 Ám; length of apical spine or horn 2-37 Ám.

Distribution. This species or species-group is rare but nearly cosmopolitan in the Gulf. It is absent at stations 27, 90, 95, 99, 130, 191, 194, and all those to the north. Its absence at marginal localities and its slightly greater frequency in the axial portion of the Gulf indicate its preference for more nearly oceanic, offshore waters. It undergoes no significant fluctuations in its frequency throughout the Gulf.
This species or species-group is widespread in Recent tropical seas. Lophocorys polyacantha Popofsky and Artopilum undulatum Popofsky are both reported from the tropical Atlantic Ocean, the latter from the tropical Indian Ocean as well.
Benson 1966
Benson, 1983, p. 505:

Lophocorys polyacantha Popofsky group

Remarks. This group is characterized by undulatory constrictions in the distally expanding abdomen and by a relatively large cephalis. Variations in members of this group are the number of abdominal constrictions, the size and shape of pores, and the degree of spininess of the cephalis (smooth surface to one with several scattered, thin, conical spines; with or without apical horn).
Benson 1983


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