N23

Carpocanistrum spp.

Carpocanium petalopsyris in Benson, 1966, p. 434, pl. 29, figs. 9, 10; Fig. 25

Carpocanium spp., Nigrini, 1970, p. 171, pl. 4, figs. 4-6

Carpocanistrum spp. Riedel and Sanfilippo, 1971, p. 1596, pl. 1G, figs. 1-6, 8-13; pl. 2F, figs. 5-6, pl. 3D, figs. 1, 2, 6, 7, 9

DESCRIPTION

"Included under this name are most of the forms commonly thought of as typical carpocaniids - with cephalis not markedly distinguished in contour from the ovate thorax, pores often longitudinally aligned, and a somewhat constricted peristome often bearing numerous teeth." (from Riedel and Sanfilippo, 1971).

"Test consisting of a cap-shaped cephalis and a thorax; cephalis hidden at top of thorax, in a few specimens separated from thorax by slight constriction but generally indistinguishable; with an internal collar ring consisting of four collar pores (cardinals and cervicals) at its base; collar ring joined to inner wall of thorax by the primary lateral and dorsal bars, which extend as ribs coincident with furrows in the thoracic wall and by a few accessory bars that arise from the collar ring and join the inner thoracic wall but do extend as ribs. Thorax variable in shape from nearly cylindrical with constricted mouth to greatly inflated, nearly subspherical, with constricted mouth. Pores of thorax equal, small, the same size as those of cephalis, arranged hexagonally in longitudinal rows (15-22 rows on the half circumference), subcircular to hexagonal; surface of intervening bars variable from smooth to one with hexagonal frames surrounding pores. Mouth constricted, in most specimens surrounded by a hyaline peristome (4-16 microns in length), peristome absent in a few tests. Peristome surmounted by tooth-like, lamellar to pyramidal, triangular to rectangular, terminal spines or teeth, variable in number from 0-16 or more. Teeth of some specimens triangular, converging inward, of others lamellar or rectangular, extending vertically downward. A few specimens with a few adjacent teeth fused together. One specimen observed with all teeth fused together to form a vertical, lamellar, hyaline extersion of the peristome. Another specimen observed with similar peristomal extension but not hyaline, instead with pores similar to those of the thorax giving the appearance of a rudimentary abdomen separated from the thorax by a hyaline septal ring." (from Benson, 1966).

DIMENSIONS

"length of test (not including terminal teeth) 80-107 microns, of cephalis (when visible) 15-20 microns; breadth of thorax 59-98 microns; length of peristomal teeth 5-33 microns." (from Benson, 1966)

"overall length 90 +/- 7 microns; maximum width 71 +/- 6 microns, based on 17 specimens" (from Sachs, 1973).

Plate 21, figures 1a-c

N24

RECENT DISTRIBUTION

1. Benson, 1966 (Carpocanium petalospyris); "confined to the southern two-thirds of the Gulf [of California]. It is rare at all stations where present but has a slightly greater frequency in the southern half of its range."

2. Nigrini, 1970, fig. 31; "For the purposes of the present study, all specimens of the Carpocanium-Carpocanistrum form were considered together except for the distinctive Carpocanium sp. A. (Nigrini, 1968 p. 55, Pl. 1, fig. 5)."

Belongs to a tropical assemblage derived by recurrent group analysis of North Pacific samples, but ranges too far north to be meaningful in down-core analysis.

3. Sachs, 1973, Code 29N (Carpocanium spp.); "rare (to about 2%), but exhibits markedly Southern preferences."

4. Molina-Cruz, 1975, Code N4 (Carpocanium spp.) used in factor analysis of southeast Pacific assemblages; cf. Appendix 10 for percent N4 at each station. Note that Molina-Cruz includes Carpocanistrum sp. A. in his counts.

5. Robertson, 1975 (Carpocanium spp.); "This species loads most heavily in factor 2 (subtropical). Its highest abundances are in the southeastern part of the study area at the present. At 18,000 YBP similar abundances are shifted about 5 degrees further to the south, but only in the east."

Note that Robertson does not include Carpocanistrum sp. A. in his counts.