Benson 1966 - Lithocircus vinculatus

Majority of tests with a noncoplanar, horizontal basal (collar) ring arising from the lower corners of the asymmetrical D-shaped sagittal ring and a kidney-shaped frontal ring (meridional), lying in the lateral plane of the test and comprising two hemi-cardioid rings, each of which arises from the midpoint of the superior bar and extends laterally, curving downward to join with each half of the basal ring at its lateral extremities. Bars of the sagittal ring three-bladed in section except for a short cylindrical median bar which occupies the dorsal one-fifth to one-third of the lower bar of the ring. Thin, conical, primary lateral spines of variable length, in a few specimens joining with the basal ring to form collar pores; a short, thorn-like axial spine present; dorsal spine thin, conical, of variable length, absent in a few specimens; secondary lateral spines possibly represented by the dorsal bars of the basal ring. Apical bar of ring straight, with or without short lateral spines; a thin, conical apical spine extends from and is collinear with it, of variable length, absent in a few specimens. Vertical bar angulated, its proximal portion nearly horizontal; vertical spine arises from its distal portion above the lower ventral corner of the D-ring and is represented by a short blade-like thorn or thin spine. Several, 4 to 6 or more, nodes of paired lateral spines located along the sagittal ring, three pairs of which extend as the bars of the basal and frontal rings, the other nodes represented by thin, conical, laterally extending spines. Bars of the frontal and basal rings circular in section, with numerous thin, conical by-spines of variable length (1-75 µm) and number, more or less regularly disposed, 8-12 on the basal ring, 5-15 or more on the frontal ring. Frontal ring shows the greatest variation of the structures comprising this species. In a few specimens the two halves of the frontal ring do not arise from the same point on the sagittal ring. In several specimens one or both halves of the ring are forked before joining with the basal or sagittal rings or both. In a few specimens the lateral portion of one or both halves is represented by a partially developed, irregular lattice, not unlike that of Eucoronis ? sp. In a few tests a thin zygomatic ring is partially developed.

Measurements: based on 65 specimens from station 27, 34, 46, 56, and 60: sagittal height of test 69-105 µm; maximum height of frontal ring 74-139 µm; maximum breadth of frontal ring (both halves) 123-196 µm; maximum length of basal ring (both halves) 68-141 µm; maximum breadth of basal ring (dorsal-ventral) 53-74 µm; height of sagittal ring 63-98 µm, breadth 52-85 µm; length of apical spine 0-30 µm, of vertical spine 0-15 µm, of dorsal spine 0-25 µm, of axial spine 0-11 µm, of primary lateral spines 3-14 µm, if incomplete, 31-37 µm if joined with basal ring.

Remarks: Most specimens conform to Haeckel's illustration and description of Eucoronis nephrospyris Haeckel (1887, p. 977, Pl. 82, fig. 5).Those that do not are recognizable by the presence of the basal ring and some structure corresponding to a part of the frontal ring. The presence of incompletely developed, thin, primary lateral spines is characteristic of this species as well as of Eucoronis ? sp.

Distribution: This species is cosmopolitan but rare in the Gulf, occurring as far north as station 208.It is absent at stations 90, 130, 151, 194, 203, 206, and 214.It may be controlled in part by upwelling because its highest frequency (3.6%) was observed at station 91 in a region of upwelling off the Baja California coast. It is very rare at station 99; therefore, if affected by upwelling it is apparent only near station 91.Its frequency in the southern half of the Gulf is greater than in the northern half. Although nearly cosmopolitan it has greater affinity for oceanic waters than for Gulf waters. Haeckel (1887, p. 977) states that this species is cosmopolitan at the surface and at various depths in all oceans including the Mediterranean Sea. It has not been reported at high latitudes. \ From: Benson, 1966, p. 304-306; pl. 21, figs. 6-8: Eucoronis nephrospyris HaeckelEucoronis nephrospyris Haeckel, 1887, Challenger Rept., Zool., vol. 18, p. 977, Pl. 82, fig. 5.

References: