Benson 1966 - Tholospyris devexa

Fully developed tests ellipsoidal to discoidal, generally with two lateral constrictions separating an apical and basal, subconical to subhemispherical, latticed cap or cupola from a larger middle portion. Internal structure and longest, intermediate, and shortest axes of the complete test the same as in Amphispyris subquadrata. Lateral bars arising from the sagittal ring similar in orientation to those of A. subquadrata but do not form rings, instead, meet laterally at one or two points or branch and anastomose distally; bars three-bladed in section, not circular. Sagittal ring three-bladed, asymmetrical, with shape similar to ring of A. toxarium, with five, in a few specimens 3 or 4, nodes from which originate the lateral bars; with a short, cylindrica1 median bar and short, thin, conical dorsal and axial spines and thin primary and secondary lateral spines of variable length; in some specimens the latter two join with the basal lateral bars originating from the sagittal ring to form collar pores; apical spine heavy, branches distally to form part of the lattice of the apical cap; vertical spine similar to that of Amphispyris subquadrata. Lattice of test irregular, first developed laterally, later filling the spaces on the dorsal and ventral surfaces of the test; lattice of cupolas similar to that of middle portion of test. Most specimens not fully developed, consisting of the laterally joined lateral bars and sagittal ring of the middle section and generally without lattice development. Sagittal ring without well-developed lateral bars rare, or, if present, not readily identifiable.

Measurements: based on 55 specimens from stations 27, 34, 46, 56, 60, 81, 71, 92, 93, and 106: longest axis of test (4 specimens) 166-172 m, intermediate axis (lateral) 79-154 µm,shortest axis (dorsal-ventral)(6 specimens) 53-86 µm; height of sagittal ring 55-71 µm, breadth (1 specimen) 43 µm; ; sagittal height of middle portion of test 55-92 µm; length of apical spine (unbranched portion of bar) 0-36 µm, of vertical spine 4-10 mm, of dorsal spine 6-10 µm, of secondary lateral spines 5-33 µm, of primary lateral spines 2-31 µm, of axial thorn 2-5 µm.

Remarks: This species is similar to Microcubus zonarius Haeckel (1887, p. 998, Pl. 94, fig. 8) because incompletely developed specimens of the Gulf species that are lacking the apical and basal cupolas are similar to Haeckel's illustration. They differ only in the presence of three-bladed instead of cylindrical lateral ribs or rings. Without reference to Haeckel's type material, identification is not positive.

Distribution: This species occurs as far north as station 184 in the Gulf but is less abundant in the Gulf than A. toxarium. It is very rare at all stations but has a more general occurrence in the southern half of the Gulf. It is absent at stations 130, 133, 151, and all those north of station 184.It is, therefore, an oceanic species not affected by upwelling in the Gulf. Haeckel reported Microcubus zonarius fromChallengerstation 271 at the equator in the central Pacific. Due to the uncertain identification of the Gulf species nothing can be stated about its world-wide distribution. \ From: Benson, 1966, p. 300-302; pl. 20, figs. 13-14; pl. 21, figs. 1-4:Amphispyris aff. zonarius (Haeckel)

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