Description - Add description
|Eucyrtidium seriatum J÷rg. in Gran L. 70, p. 150 (nomen nudum).|
A many-jointed form. The uppermost joints are convex and increase in size so that the diameter of the fifth is from three to four times as great as that of the first. The lower part is more or less distinctly cylindrical. On the cephalis, there is a short broad tophorn. The pores below are roundish rectangular, in very distinct, regular, horizontal rows.
The number of the joints varies, probably according to age. Uppermost there is a low, semispherical (or broader) cephalis, then short joints, which increase evenly in width up to the fourth or fifth, which is usually the broadest. From the sixth joint, which is decidedly narrower, the width decreases, but very slowly, so that the lower part is almost cylindrical, only a little narrower below. I have not seen more than eight joints. These lower joints in the cylindrical part are not plainly divided off from each other.
The upper part of the shell is shaped like a high cone. There is a short, broad, three-edged (?) tophorn protruding from an inner skeleton in the two upper joints.
It is not easy to see these inner skeleton parts which are, at all events, in a high degree retrograded, for it is a difficult matter to examine the shell from the open end, and the outer lattice shell in side view hides the short, primary spines. So I have not been able definitely to decide whether this genus has the same primary skeleton parts as the foregoing ones. Neither have I been sure if protruding basal spines exist in the two upper joints (the apical spine only excepted).
The shape of the cephalis in some positions of the lattice shell might suggest that also inner primary arches are to be found, and not only the primary spines.
It is doubtful whether there is a protruding ventral, sagittal spine.
On the other hand, a long, inner axial spine is plainly visible. It seems to consist of three or more long, parallel branches, which reach down through more than half the length of the lattice shell.
The central capsule also reaches far down through the shell.
The pores on the cephalis are small, round, widely apart and scattered. On the second joint, they are perhaps a little larger, on the third somewhat smaller again, and from here they are regularly placed in horizontal rows. From the fourth joint and downwards, the pores become more irregular in form and size, from quite small and round to rather large, roundish rectangular in shape, although generally speaking they are small and always in regular, horizontal rows. On the cylindrical lower part, they are also placed in more irregular vertical rows. The average size of the pores does not increase, at any rate noticeably, from the fourth joint downwards.
This species varies rather considerably. For instance, its greatest width may be either in the fourth or fifth joint, and there are often irregular contractions in the lower part. It is doubtful whether any of the individuals illustrated are fully developed. On the best developed specimen (J°rgensen 1905, fig. 102) the lower margin was regularly dentate. Often young individuals may be found consisting of only a few joints and entirely without the cylindrical lower part.
Height, up to 128Á, greatest width 72Á. Pores, up to 6Á.
The species resembles the one illustrated by Cleve (1899, pl. 2, figs. 5-6), which he calls Lithomitra australis EHRB. It is probable that the same basal spines are present in this species, protruding as fine needles, as in Androcyclas gamphonycha and Clathrocyclas craspedota. Even if these spines are present, Haeckelĺs name for the genus might in this case be retained without any great disadvantage.
Rather rare, always in small numbers and only in deep water samples.
Distribution: In surface samples, 2/2 1901, off S°ndm°re, 13/2 off Lofoten and 5/3 off Finmark. Most probably a boreal oceanic species.
|Benson, 1966, p. 523-527; pl. 35, fig. 14 (not 15-17); text-fig. 28:|
Siphocampium cf. cornutella Haeckel
?Spirocyrtis cornutella Haeckel, 1887, Challenger Rept., Zool., vol. 18, p. 1509, Pl. 76, fig. 13.
?Stichocorys seriata J°rgensen, 1905, Bergens Mus. Skrifter, p. 140, Pl. 18, figs. 102-104 [=Eucyrtidium seriatum J°rgensen in Gran, 1902, Rept. Norwegian Fishery-and-Marine-Investigations, vol. 2, no. 5, p. 150].
Smooth, spindle-shaped to conical test with numerous (4-10) inflated to cylindrical joints of unequal length separated by distinct constrictions coincident with narrow hyaline rings which are not raised internally within the test cavity. Cephalis is relatively broad, hemispherical, with a short, stout, three-bladed apical spine, a broad, trumpet-like, ventral cephalic tube, and six collar pores at its base (text-fig. 28). Dorsal and primary lateral bars extend as indistinct or slightly raised thoracic ribs which terminate in short, thorn-like spines in several specimens. Vertical spine short, extends within the proximal portion of the interior of the ventral tube. Pores of cephalis subequal, circular to subpolygonal, regularly to subregularly arranged. Thorax campanulate, in a few tests with an angular shoulder at its base, with subequal, circular to rectangular pores, 1-2 times the width of the intervening bars, arranged in 3-5 transverse rows. Abdominal joints generally of small unequal lengths, but in a few tests some are relatively long. Joints of most tests inflated truncate-conical or cylindrical, in a few tests with straight sides and angular constrictions between them. In most specimens the middle joints are broadest, in others the distal joints. Terminal margin incompletely developed, mouth not constricted. Pores of abdominal joints arranged in transverse rows, 3-4 on small joints, pores of each row approximately equal, elliptical to rectangular; rows generally widely separated but in a few tests, particularly those with straight-sided joints and angular strictures, pores arranged hexagonally in transverse rows and separated by narrow intervening bars throughout.
Measurements; based on 30 specimens from stations 27, 34, 192, and 208: maximum length of test 107-252 Ám, maximum breadth 59-106 Ám; length of cephalis 15-20 Ám, of thorax 17-21 Ám; breadth of cephalis 18-25 Ám, of thorax 36-46 Ám; length of apical spine 7-17 Ám, of ventral tube 6-17 Ám.
Remarks. This species is distinguished from Siphocampium cf. seriatus by its more numerous, shorter, irregular joints which in several specimens have square shoulders, by the generally larger pores of the joints, and by the lack of broad, hyaline septal rings with vertical ridges. In details of the cephalis it is identical with S. cf. seriatus (text-fig. 28).
Haeckel 's illustration of Spirocyrtis cornutella is nearly identical with many of the specimens of the Gulf species. It differs in the apparent lack of a ventral cephalic tube (a feature that Haeckel may have overlooked), the curved axis of the test (observed in a few specimens from the Gulf), and the presence of spirally-arranged constrictions of the shell, a feature which is not obvious in his illustration. If examination of Haeckel's type material reveals the presence of a ventral cephalic tube, this species would be identical with the Gulf species and would conform to the genus Siphocampium Haeckel. The shape, size, and number of joints and the nature of the pores of Stichocorys seriata J°rgensen are identical with the species from the Gulf. This species apparently lacks a ventral cephalic tube, and J°rgensen (1905, p. 140) states that a long inner axial spine seeming to consist of three parallel branches is present but is not shown in his illustrations. Study of the type material of this species as well as of Lithamphora furcaspiculata Popofsky (1909, pp. 295-296; 19l3, pp. 408-432) is necessary before the taxonomic significance of the axial spines can be determined. Although a short, thorn-like axial spine is present in several specimens of Gulf species belonging to Siphocampium Haeckel, it is not long or multiple as in J°rgensen's or Popofsky's species. In those it apparently serves as a support for the downward-hanging lobes of the central capsule. The absence of these spines in the Gulf species may have either taxonomic or ecological significance, or both.
Distribution. This species is cosmopolitan in the Gulf but has a much higher frequency in the northern half. In the southern Gulf it is common (2.4%) only at station 93 and rare to very rare at the other stations except 90 where it is absent. It does not appear to respond to upwelling in this region of the Gulf. It apparently prefers offshore, more nearly oceanic waters in the southern Gulf. In the northern half of the Gulf it is common at all stations except 208 where it is abundant (11.4%), 130 and 194 where it is very rare, and 203 and 214 where it is absent. It is the most abundant species at station 192 (7.8%), the second most abundant at station 206 (11.4%), the third most abundant at stations 151 (6.0%) and 191 (6.5%), and the fourth most abundant at stations 115 (4.4%), 133 (4.2%), and 136 (4.4%). With the exception of stations 184 (4.0%), 206, and 208, the northern Gulf stations at which it occurs commonly are located within the diatomite facies. Although sediments from stations 184 and 206 have low percentages of diatoms, this percentage is relatively high at station 208. This species, therefore, responds significantly to upwelling that accounts for high diatom production. Its general northward increase in frequency in the southern Gulf as well as its high frequency at northern Gulf stations, particularly at 184 and 208, suggests its possible affinity for Gulf waters with higher than average temperature and salinity. The relative importance of this as opposed to upwelling in the control of the distribution of this species cannot be determined without further ecological studies.
Spirocyrtis cornutella Haeckel was reported from "Challenger" station 270 in the central tropical Pacific. Stichocorys seriata J°rgensen (1905, p. 140) is rather rare and occurs only in deep water samples from Norwegian fjords. J°rgensen (loc. cit.) states that this species is most probably a boreal oceanic species. If the Gulf species is identical with these two species, it has a cosmopolitan distribution.