Larcopyle buetschlii group
Description - Add 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.
|Benson, 1966, p. 279-280; pl. 19, figs 1-2:|
Test a relatively small, elongate ellipsoid, with a smooth surface and at one pole a cluster of short (4-21 µm) thorns or spines but without a definite opening except for the pores of the latticed shell. Surface of test smooth but slightly irregular; pores irregular, of unequal size, many representing secondary pores filling the spaces of larger pores. Internal structure appears as a loose, spongy network; in a few specimens internal shadows appear to have some kind of arrangement, either spiral or concentric, but if a trizonal structure does exist, it is irregular.
Measurements; based on 30 specimens from stations 71, 81, arid 136: major diameter of test 82-151 µm, minor diameter 60-105 µm.
Remarks. This species is distinguished from Larcopyle bütschlii by its relatively small size, its smooth surface without radial spines, and the presence of secondary pores filling the spaces of the larger pores of the outer shell. Although without a definite pylome, the cluster of spines at one pole resembles one and is similar to the apparent pylome of Larcopyle bütschlii Dreyer (1889, Pl. 10, fig. 70). For these reasons it is placed within the genus Larcopyle Dreyer (1889, p. 124). Because the internal structure of this species is not definitely known, it was not given a new species name.
Distribution. This species is cosmopolitan in the Gulf, being absent only at stations 90, 203, 206, and 214. It is rare at all stations except 64, 71, 81, 99, and 133 where it is common. Its highest (4.0%) and second highest (3.0%) frequencies were observed at stations 64 and 99, respectively, both located in known areas of upwelling off the coast of the Mexican mainland. Station 133 is located in the diatomite facies in a known area of upwelling off the Baja California coast. Stations 71 and 81 are located near areas of upwelling off both coasts. The frequency of this species does not increase in other areas of upwelling, although at station 192 it is almost common. The distribution of this cosmopolitan species in the Gulf, therefore, is controlled locally by upwelling.
|Benson, 1983, p. 504-505:|
Larcopyle butschlii Dreyer group
Remarks. This group of ellipsoidal tests with regular outline is identified on the basis of its internal pylonid structure and the presence of a cluster of spines at one pole of the test.