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Botryocyrtis scutum (Harting, 1863)

Description - Add description

Benson, 1966, p. 345-348; pl. 23, fig. 16; text-fig. 23:

Botryopyle sp.

Apical part of test consisting of two prominent lobes, the central higher lobe being the cephalis, the larger but lower lobe being a dorsal lobe, and either a single small ventral lobe or a pair of ventro-lateral lobes situated ventrally below the cephalis. Joints below apical portion of test subcylindrical, variable in number, of approximately the same breadth, generally one or two short ones (thorax and first abdominal joint) above and a larger one (second abdominal joint) open at the base below; joints separated by annular constrictions; as many as five equal joints present in one specimen. Surrounding the test below the apical portion is an outer mantle consisting of dense silica with very irregular pores; it is approximately conical but is generally constricted at its base where it merges with the wall of the lower abdominal joint above the mouth; in a few specimens the conical outer mantle does not join with this joint and is open at its base; at the approximate level of the thorax or first abdominal joint there is an irregular tube or opening on the ventral surface of the outer mantle. In a few specimens long, thin, conical spines arise from the outer mantle and generally extend downward; the surface of the outer mantle is rough with numerous thorns or short spines. The test is compressed laterally, therefore, is elliptical in transverse section. Subspherical cephalis and dorsal lobe nearly hyaline but outline of infilled pores visible; walls relatively thick. Joints below cephalis with thick walls and irregular pores arranged in transverse rows (barely visible); mouth of last joint open, in some tests constricted. Ventro-lateral lobes generally covered by the outer mantle which in a few tests covers the cephalis and dorsal lobe as well. Internal structure illustrated in text-fig. 23. Cephalis separated from collar ring by large pores. Collar ring with cervical and cardinal pores. Primary lateral bars extend as thoracic ribs and terminate in short spines which do not reach the outer mantle. Dorsal bar a rib in the upper latticed surface of the thorax (base of dorsal lobe), with 2-3 pores on either side of it. Secondary lateral bars do not extend beyond collar ring. A short, thin, conical vertical spine free within cavity of ventral or ventro-lateral lobes. Apical bar a dorsal rib in the cephalic wall, vertical, extends as a short conical spine.

Measurements; based on 8 specimens from stations 27, 34, and 60: height of cephalis 21-24 µm, of dorsal lobe 25-29 µm, of ventral lobe 10-13 µm; breadth of cephalis 16-20 µm, of dorsal lobe 17-21 µm, of ventral lobe 8-12 µm, of thoracic and abdominal joints 48-55 µm; length of complete test 89-124 µm, maximum breadth (outer mantle) 65-82 µm.

Remarks. Several species that resemble the Gulf species are very similar in the presence of two prominent lobes, one of which is central and higher than the other, but they differ in the apparent absence of an outer mantle. In many specimens from the Gulf the outer mantle is difficult to distinguish from the inner joints, but a sufficient number of specimens were observed to verify its presence. None of the illustrations of previously described species similar to this one show the presence of the outer mantle; if present in these forms it was undoubted1y overlooked because it is not mentioned in the descriptions. Because the species in question is rare in the Gulf and a possibility exists that it belongs to a previously described species, a new species name was not proposed. The presence or absence of the outer mantle may be subject to intraspecific variation, but it is present in all the Gulf specimens studied.
Species that appear to be closely related to this species, if not the same species, include Botryopyle? antarctica (Haecker) described by Riedel (1958, pp.244-246, Pl. 4, fig. 12; text-fig. 13) who placed Saccospyris antarctica Haecker (1907, p. 124, figs. 10a, b; 1908, pp. 447-448, Pl. 84, figs. 584, 589, 590) in synonymy with it; Lithobotrys homunculus Popofsky (1913, pp. 317-318, Pl. 31, figs. 5,6); Botryopyle hexapora Popofsky (op. cit., p. 318, text-fig. 27); and B. erinaceus Popofsky (op. cit., p. 319, text-fig. 28, 28a). All of these species are characterized by the two prominent lobes (the central cephalis and a large dorsal lobe) but vary in details of the thorax. Of these species only L. homunculus and B. hexapora have a ventral tube arising from the approximate level of the first or second joint below the cephalis.
Riedel (1958, p. 245, and text-fig. 13) described and illustrated the internal structure of Botryopyle? antarctica (Haecker). His interpretation is more complicated than the author's interpretation of the internal structure of Botryopyle from the Gulf (text-fig. 23). The cervical pores appear to correspond to those labeled g and g' in Riedel's illustration; the cardinal pores correspond to those labeled f and f'. The dorsal bar occurs as a rib in the upper surface of the thorax or first joint. The two to three large thoracic
pores which lie on either side of the dorsal bar probably correspond to the pores labelled a, a', and b, b' of Riedel's illustration.

Distribution. This species is very rare in the Gulf but is the most abundant of the four cannobotryd species present. It is generally confined to the southern part of the Gulf, occurring at stations 27, 34, 46, 56, 60, 64, 71, 93, and 95. In the northern Gulf it is present only at station 136. It is, therefore, a species with greater affinity for oceanic than for Gulf waters.
Because doubt exists as to the identification of this species, no definite statement concerning its world-wide distribution can be made. According to Riedel (1958, p. 246), Botryopyle? antarctica has a cold-water, bipolar distribution. Lithobotrys homunculus Popofsky, Botryopyle hexapora Popofsky, and B. erinaceus Popofsky were reported from the tropical part of the Indian Ocean (Popofsky, 1913, pp. 317-319). The Gulf species may be cosmopolitan, occurring at all latitudes, if it can be positively identified with the above species.
Benson 1966











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