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Larcopyle titan (Campbell and Clark, 1944)

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Prunopyle titan
Shell generally ovate, large, with disctinct osculum; egg-shapped shell stoutly proportioned (1,5-1,6 times its maximum diameter in length), with evenly contoured walls which round off at unmodified apical end and which end antapically at extended osculum; osculum subtubular, very short (less than 0,1 total length in lenth and 0,2 greatest diameter in diameter), with about 16 projecting, slightly incurved spines around its margin and acting as stays; wll fairly thick; surface smooth; pores of shell very closely set, small (less than 4,4μ), circular, at inner ends of tubules connecting with surface, tubules mostly directed apically, pores on osculum similar but set farther apart, and not deep-set. Length, 280μ, of tunular osculum, 40μ.
Prunopyle titan n.sp differs from Eocene species occidentalis (1942) in shape and in prominence and character of osculum. Two species not closely related, and neither has an inner concentric medullary shell.
Presence of several different sizes of individuals among specimens examined in this Miocene material suggests strong influence of temperature upon shell formation. As with other pelagic protozoans, notable loricate ciliates, this accounts for presence of many dwarfed individuals among species otherwise large in size. These small individuals are thus probably not the result of unusual water conditions or other adverse factors in environment but rather follow perhaps normal temperatures changes in medium. That these small individuals are younger than larger individuals is hardly possible as these shell appears to lack intussusceptional growth. Both large and small individuals occur side by side but may have been formed at different times.
Campbell & Clark 1944
Larcopyle titan
Remarks. In comparison to L. p. titan, true L. titan is more nearly spherical in overall shape, has a largely non-spinose outer shell, and the interior structures are poorly developed, being either weakly spongiose or, in many specimens, nearly hollow. Several specimens from Campbell & Clark’s (1944) type series material are re-illustrated in Plate 4. True L. titan is restricted to earlier Miocene sediments in the Antarctic. Campbell & Clark comment on a large size range in this species, but this has not been noted in the specimens curated in the Museum in Berkeley, which also are slightly smaller (c. 200 µm) in length, not counting pylome, than given by Campbell & Clark (1944).
Lazarus et al 2005











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