N67

Anthocyrtidium ophirense (Ehrenberg)

Anthocyrtis ophirensis Ehrenberg, 1872a, p. 301; Haeckel, 1887, p. 1270

Anthocyrtidium ophirense (Ehrenberg), Nigrini, 1967, p. 56, pl. 6, fig. 3

DESCRIPTION

"Cephalis complex, elongate, ovate-cylindrical, with subcircular pores, bearing a three-bladed apical horn usually of about the same length as the cephalis. Thorax campanulate, inflated, with constricted mouth, having circular to subcircular pores hexagonally arranged, usually hexagonally framed, separated by rather delicate bars. Subterminal row of 8-11 sharp, 3-bladed teeth usually prominent, but in some individuals absent or scarcely discernible. Distally from the subterminal teeth, the thoracic wall curves inward abruptly, to terminate at a narrow delicate lamellar peristome. One or two thoracic pores between subterminal teeth and peristome. Peristome often bears inconspicuous, small triangular teeth directed either downward or inward, forming a terminal row." (from Riedel, 1957).

"Riedel (1957, p. 84) synonymized Anthocyrtidium cineraria Haeckel and Sethocyrtis oxycephalis Haeckel and described what he interpreted to be a single species. The present author does not believe that these species are identical, and consequently 2 separate species, A. ophirense (=A. cineraria) and A. zanguebaricum (=S. oxycephalis), are distinguished herein. Riedel's description was based, in part, on Indian Ocean material, and specimens found during the present study agree in most respects with his observations. However, A. ophirense has an apical horn which is always longer than the cephalis, and subterminal teeth are almost always well developed. A. zanguebaricum has a shorter apical horn, and subterminal teeth are poorly developed or absent." (from Nigrini, 1967).

DIMENSIONS "Length of apical horn 45-90 microns; of cephalis 27-36 microns; of thorax 81-119 microns; of subterminal teeth 9-27 microns. Maximum breadth of cephalis about 27 microns; of thorax 90-136 microns." (from Nigrini, 1967).

REMARKS

1. For a more complete synonymy see Nigrini, 1967.

2. Benson's (1966) description and dimensions of this species (A. cineraria Haeckel in Benson, p. 472) are consistent with the above.

Plate 25, figure 1

N68

RECENT DISTRIBUTION

1. Benson, 1966 (Anthocyrtidium cineraria); "This species is much rarer in the Gulf [of California] than [A. zanguebaricum]...appears to be an oceanic species."

2. Nigrini, 1967, fig. 30; "Indian Ocean occurrences - A. ophirense is abundant in low latitudes, but south of 35 degrees S, it never forms more than 1 percent of the described population. It appears to be a reliable and potentially useful member of the low latitude assemblage."

3. Nigrini, 1970, fig. 32; belongs to a tropical assemblage derived by recurrent group analysis of North Pacific samples, but the species does range as far north as 40 degrees N in the western and central Pacific.

4. Lozano, 1974, Fig. IV-1; "Present in a few samples from the Indian Ocean sector and only in core V27-191, the northernmost sample in the Atlantic Ocean. Maximum abundance of 0.5 percent in core V24-202. Found under waters with February sea surface temperature 18 degrees C. Its southernmost appearance is in core RC11-101 (0.1%)."

5. Molina-Cruz, 1975, Code N2; used in factor analysis of southeast Pacific assemblages; cf. Appendix 10 for percent N2 at each station.