|Is Lithostrobus cuspidatus the same as Lithostrobus tristichus?|
Jane K. Dolven (18/11/2004)
|Lithostrobus cuspidatus was for the first time described and figured (as Eucyrtidium cuspidatum) by Bailey 1856. Eucyrtidium cuspidatum was later mentioned and figured by Ehrenberg in 1872, but Ehrenberg’s figure was slightly different from the one by Bailey 1856 (see original drawings). Bütschli 1882 changed the genus from Eucyrtidium to Lithostrobus.|
Haeckel 1887 divided Lithostrobus cuspidatus into two different species, mainly based on if the joint-length and number of pore rows were increasing or not (see both Haeckel’s descriptions below):
#1) Lithostrobus cuspidatus: “Joints gradually increasing slightly in length… two rows in the first, three in the second, four in the third, seven in the eighth and following joints”. This he said was synonymous with Eucyrtidium cuspidatum described and figured by Ehrenberg 1872.
#2) Lithostrobus tristichus: “All joints nearly of the same length… In each joint three transverse rows of pores...”. This he said was synonymous with Eucyrtidium cuspidatum described and figured by Bailey 1856.
But should Haeckel not here, according to the nomenclature rules, have used the name L. cuspidatus for the one originally described by Bailey 1856, and given the one described by Ehrenberg 1872 another name (e.g. Lithostrobus tristichus)?
In the Nordic Seas there are very few specimens present in the surface sediments, but those I have seen have joints with 3 or 4 rows of pores, and this is not put in any particular system. These specimens do therefore not fit exactly with any of the two descriptions given by Haeckel (1887).
Could it be that Lithostrobus cuspidatus and Lithostrobus tristichus is actually the same species and that the joint-length and number of rows are just a result of intra-specific variation?
Lithostrobus cuspidatus (p. 1473):
Shell, slender, conical, smooth, with straight axis, and ten to twelve distinct strictures. Joints gradually increasing slightly in length, the tenth twice as long as the third. Pores circular, in regular transverse rows; commonly two rows in the first, three in the second, four in the third, seven in the eighth and following joints. Horn of the cephalis long, bristle-shaped, curved. This species called Eucyrtidium cuspidatum by Ehrenberg, differs from Lithostrobus tristichus, to which Bailey had given the same name.
Dimensions: Length of the shell (with ten joints) 0.2; length of the tenth joint 0.03, breadth 0.06.
Habitat: North Atlantic (Greenland, Ehrenberg); Station 348, depth 2450 fathoms.
Lithostrobus tristichus (p. 1469):
Shell slenderly conical, smooth, with straight axis, and eight to ten deep strictures. All joints nearly of the same length, the eighth joint twice as broad as the third. In each joint three transverse rows of pores. Horn of the cephalis bristle-shaped, strongly curved about as long as the shell. (Ehrenberg confounds this species with Lithostrobus cuspidatus).
Dimensions: Length of the shell (with eight joints) 0.16, of each joint 0.02; breadth of the fourth joint 0.04, of the eight 0.08.
Habitat: North Pacific, Kamtschatka (Bailey); Station 241, depth 2300 fathoms.