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Cubotholus octoceras Haeckel, 1887

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All six cupolas in pairs of different sizes. Both principal domes larger than the lateral domes and these larger than the sagittal domes. Pores subregular, circular, twice as broad as the bars; eight to ten in the semicircle of each cupola. From the surface arise (at the intersecting points of every three cupolas) eight strong conical spines, about as long as the shell-axis; they lie in two diagonal planes, and are the external free prolongations of eight inner beams (homologous with the eight wing-spines of Tetrapyle octacantha), which connect the lentelliptical medullary shell with the eight corners of the cuboidal central chamber.
Dimensions.ŚMajor axis of the cortical shell 0.15, middle 0.13, minor 0.11; pores 0.008, bars 0.004; diameters of the medullary shell corresponding to 0.05, 0.04, 0.03.
Haeckel 1887
Benson, 1966, p. 260-262; pl. 17, fig. 8:

Cubotholus cf. octoceras Haeckel

?Cubotholus octoceras Haeckel, 1887, Challenger Rept., Zool., vol. 18, p. 681.

Internal structure similar to that of Amphitholus acanthometra. Test consists of the basic Amphitholus-like shell, which is larger than A. acanthometra, with the addition of four large, dome-shaped, latticed cupolas, each at the poles of the principal and sagittal axes of the test. The cupolas at the poles of the principal axis are larger than those at the poles of the sagittal axis; the latter are slightly larger than the lateral cupolas of the Amphitholus-like shell. Pores and surface of the test the same as in A. acanthometra. Fourteen primary beams generally recognizable but additional beams present as well. Numerous (5-50 or more) long, conical radial spines present, most of which are not continuous inward as beams; spines of variable length on the test (6-62 Ám), but those continuous inward with the 14 primary beams are generally the longest. No specimens were observed with an outer lattice-mantle, but if more specimens were available for study it may be found to be present.

Measurements; based on 4 specimens from stations 27, 81, and 184: length of principal axis of complete test 141-185 Ám, of transverse axis of complete test 98-181 Ám.

Remarks. This species was tentatively identified as Cubotholus octoceras Haeckel because it is the only species of Cubotholus that Haeckel described as having radial spines. Only the eight diagonal spines are present, however. Because it is not illustrated, it cannot be positively identified with the Gulf species. Of Haeckel's illustrated tholonid species, only Tholoma metallasson Haeckel (1887, p. 672, Pl. 10, fig. 13) resembles the Gulf specimens. It differs from them in the absence of the inner trizonal shells and in the presence of only four cupolas which are covered by a relatively thick-walled, equal-pored outer shell conforming to the shape of the inner cortical shell. Study of the type material of this species may reveal that it has the same internal structure as Cubotholus because observation of this structure is difficult.

Distribution. This species occurs rarely at only four stations in the Gulf, namely, 27, 34, and 81 in the southern Gulf and at 184 in the northern Gulf. Cubotholus octoceras was reported by Haeckel from the western tropical Pacific at "Challenger" station 224. This species, as well as perhaps all tholonid species, appears to be confined to tropical seas because none of them have been reported from high latitudes.
Benson 1966


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