Comprehensive Description

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Description

Benson, 1966, p. 280-282; pl. 19, figs. 3,5, (not 4):  Larcopyle bütschlii Dreyer   Larcopyle bütschlii Dreyer, 1889, Jenaische Zeitschr. Naturwiss., vol. 23, pp. 124-125, Pl. 10, fig. 70.   Large ellipsoidal shell when fully developed with regular outline; surface with scattered short (5-25 µm) conical spines or thorns continuous inward as beams; pores unequal, irregular, larger than those of preceding species [Larcopyle? sp]; at one pole in a few specimens a cluster of short (5-12 µm) conical spines but without definite opening or pylome. Internal structure consists of irregular but generally recognizable latticed lamellae joined by numerous radial beams, in several specimens with an identifiable pylonid structure of concentric trizonal shells or spirals, particularly apparent in those with outer shell not fully developed (Pl. 19, figs. 3-4). Those specimens with a recognizable internal triangular pylodiscid shell were placed within Discopyle ? sp.   Measurements; based on 30 specimens from stations 71, 81, 136, and 184: major diameter of test 135-246 µm, minor diameter 81-172 µm; length of axes of internal trizonal shells (8 specimens): P1 18-33 µm, P2 59- 95 µm, T1 14-18 µm, T2 39-74 µm.   Remarks. This species is identified as Larcopyle bütschlii on the basis of the internal pylonid structure and the presence of the cluster of spines at one pole. Dreyer's illustration (1889, Pl. 10, fig. 70) differs from the Gulf forms in the smooth ellipsoidal shell with more regular pores. In this respect it is more like Discopyle? sp. from the Gulf, but Dreyer (1889, p. 124) states that the internal structure is composed of trizonal shells, not pylodiscid shells. It may be that Discopyle ? sp. and this species are the same, but due to problems of orientation the pylodiscid shell is difficult to recognize.   Distribution. Specimens identifiable as this species are generally rare but cosmopolitan in the Gulf, being absent at stations 192, 203, 208, and 214 and common at stations 106 and 206. At station 206 the total population is only 201; therefore, results obtained from this station are not significantly comparable to those of other stations. A significantly higher frequency (2.8%) was noted at station 106 which is located within the diatomite basin facies; therefore, this species may be controlled in part by upwelling. It is almost common at stations 91, 92, and 93, located within and between areas of upwelling along both coasts. Throughout the remainder of the Gulf this group does not undergo any significant changes in its frequency. Because identification of these forms is difficult, interpretations regarding their distribution cannot be easily made. It is cosmopolitan in the Gulf, and its distribution in local areas may be favored by upwelling. Larcopyle bütschlii was described by Dreyer (1889, p. 125) from "Challenger" stations 232, 266, and 271. The first is located off the east coast of Japan in the Kuroshio Current, the other two in the central equatorial Pacific. This species, therefore, is at least tropical to temperate, but it has not been reported from polar latitudes.

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