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Botryostrobus bramlettei (Campbell and Clark, 1944)

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Lithomitra (Lithomitrissa) bramlettei
Shell small, elongated (2.0 maximum, or 3.3 apertural diameters, in length), with conspicuously swollen third joint, one of important distinguishing characters of species; cephalis small, rather smooth, caplike, not much pitted, apically rounded, and laterally convex; shell-joints subequal in length, third and fifth shell-joints per­haps a little longer than upper ones, strictures well marked, sometimes by transverse lines as well as by changes in lateral contour, five joints forming shell exclusive of cephalis, first two bulged like old-fashioned wedding rings and together subcorneal (30°), third ring greatly swollen (1.65 apertural diameter in diameter), fourth segment much less swollen than others, and ultimate one subcylindrical, its free edge squarely truncated, minutely toothed with subequal, subregular, discrete teeth, and its diam­eter only 0.3 total length; wall not especially thick, rather uniform, thinnest in ul­timate shell-joint, grayish; pores on cephalis rather numerous, tiny, subcircular, on shell-joints squarish, in four to seven vertical tiers of 16-36 pores in о transverse row, these pores closely set, subuniform, subequidistant, in sharply distinct rows both vertically and horizontally, surface with subvertical lines limited to upper part of swollen joint, otherwise smooth. Length, 150 μ; diameter, maximum, 70 μ, of largest pores, 6.6 μ.
Large suites of this common species available in this collection. Considerable variation in nearly all characters, yet essential characters remain distinct. In some individuals, ultimate segment contracts, in others it is laterally bulged, and in some it even flares slightly. Swollen joint is not so apparent in a few individuals as in majority of forms, and, in a few, pores tend to become subhexagons. Dimensions differ among various specimens, although not so much as to suggest other than slight variations.
Lithomitra bramlettei n.sp. resembles Siphocampe malagaensis n.sp. in general form but differs in that third rather than second shell-joint is swollen, ultimate joint is subcylindrical rather than subcorneal, and in its stouter proportions as well as lack of tubular accessory opening. Differs from biconvexa n.sp. in lateral contour and distinctness of swollen segment.

Campbell & Clark 1944
Botryostrobus bramlettei
Description: Shell usually thick-walled; surface rough. Cephalis hemispherical wi th a few subcircular pores and well-developed vertical tube, approximately cylindrical but tapering distally. Tube directed obliquely upward at about 45°. Sometimes thornlike apical horn present. Collar stricture indistinct. Thorax inflated bearing three transverse rows of subcircular pores. Lumbar stricture apparent, but not pronounced. Abdomen and first post-abdominal segment similar in shape to thorax but somewhat larger, fourth segment being the largest in both length and breadth. Four transverse rows of subcircular pores on abdomen; three to six on fourth segment. First four segments form a cone; shell then narrows sharply to an approximately cylindrical (sometimes symmetrically sinuous) segment. Termination may be poreless band with or without small terminal teeth or in some specimens the peristome consists of two poreless bands flanking single row of subquadrangular pores.
Dimensions (based on 15 specimens): Total length 105-130µ; maximum breadth 60-65µ.
Range: Very rare to few from the Cannartus (?) petterssoni Zone to the Stichocorys peregrina Zone.
Phylogeny: It seems that B. aquilonaris may be descended from B. miralestensis. It is interesting to note that the range of B. bramlettei neatly spans the gap between the uppermost occurrence of B. miralestensis and the lowermost occurrence of B. aquilonaris. suggesting that bramlettei is a transitional form.
Remarks: This species may be distinguished from B. aquilonaris by its more pronounced lumbar and post-lumbar strictures and by the characteristic change in shape from conical to cylindrical. B. aquilonaris is more spindle-shaped and is generally larger.
Nigrini 1977











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