Benson 1966 - Amphispyris subquadrata

Fully developed tests rare, consist of a large discoidal test, subquadrate in outline, with two lateral constrictions separating an apical and basal, flat cap-like lattice from the central part of the test. With respect to latticed part of test, sagittal ring rotated 90 degrees around the lateral axis from its position in Amphispyris toxarium; therefore, median bar is within test cavity and the peripheral latticed portion of the test surrounds the lateral, apical, and basal sides of the sagittal ring. The longest axis of fully developed tests is parallel to the lateral axis, the shortest axis is parallel to the dorsal-ventral axis. Most tests not fully developed, consisting of either the sagittal ring alone, ring with paired lateral spines partially or fully developed as bars or continuous rings, or ring with lateral portion of lattice complete and with or without partial development of apical and basal cap-like lattice. Sagittal ring D-shaped, three-bladed, nearly symmetrical, with six regularly disposed nodes from which arise six pairs of divergent lateral spines; four nodes each located at the corners of the ring and one each at the midpoint of its sides.A short, cylindrical median bar occupies the dorsal one-third to one-half of the lower bar of the D-shaped ring and has short, thin, conical, primary lateral spines and a short, blade-like axial spine or thorn; secondary lateral spines may be represented by the divergent lateral spines arising from the junction of the apical and median bars; dorsal spine either a free, thin, conical spine or relatively long and distally branched to form part of the basal cap-like lattice; apical spine similar to dorsal spine in its development, forming part of the apical cap-like lattice; vertical spine a blade-like thorn arising from the ventral surface of the lower half of the ventral side of the D-ring. Paired lateral spines, circular in section, arise from the lateral blades of the ring at each node, extend predominantly in a lateral direction and generally join together, commonly forming three horizontal rings-- apical, basal, and zygomatic, in some specimens forming vertical (meridional) rings, in others meeting at one or two points laterally without forming definite rings, in a few specimens branching and anastomosing distally. Zygomatic ring or lateral spines (bars) arising from the midpoints of the dorsal and ventral sides of the D-ring generally thinner, less fully developed than the other four pair of spines (bars) and are absent in a few specimens. Zygomatic bars represented on outer surface of ring at the midpoint nodes on both the dorsal and ventral sides of the ring by a horizontal raised rib, characteristic of the species (Pl. 20, fig. 10).Lattice of the test of variable development, consisting of anastomosed spines and trabeculae which arise from the lateral bars; first developed at the lateral margin of the test; dorsal and ventral surface of test generally without lattice developed between the bars; apical and basal cap-like lattice derived in a similar manner. Pores of lattice of irregular shapes and unequal sizes; surface of lattice with short spines or thorns.

Measurements: based on 60 specimens from stations 27, 34, 46, and 71: longest axis (apical to basal) of fully developed forms 114-202 m, intermediate axis (lateral) 84-174 µm, shortest axis (dorsal-ventral) not measured; height of sagittal ring 67-89 µm, maximum breadth 59-72 µm, length of primary lateral spines 1-15 µm, of vertical spine 0-6 µm, of dorsal spine 3-16 µm, of unbranched portion of apical spine (bar) 5-30 µm, of axial spine 1-9 µm.

Remarks: The distinctions between this species and A. toxarium and A. aff. zonarius were discussed in the remarks of the former. It differs from Haeckel's illustration of A. subquadrata in the presence of the distinct raised rib on both sides of the sagittal ring from which arise the lateral ribs of the zygomatic ring. Haeckel may have overlooked this feature or the specimen he illustrated has a poorly developed one.

Distribution: This species is rare in the Gulf, occurring only at stations 27, 34, 46, 56, 60, 71, 81, 91, 92, 93, 106, and 133.It occurs with greater frequency in the southern half of the Gulf and is not associated with upwelling. Therefore, it is an oceanic species with little affinity for Gulf waters. Haeckel reported this species fromChallengerstation 285 in the south Central Pacific. It has not been reported from high latitudes; therefore, it is confined to tropical and temperate regions. \ From: Benson, 1966, p. 297-300; pl. 20, figs. 8-12:Amphispyris subquadrata HaeckelAmphispyris subquadrata Haeckel, 1887, Challenger Rept., Zool., Vol. 18, p. 1097, Pl. 88, fig. 5.

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