N43

Pterocanium praetextum (Ehrenberg) eucolpum

Pterocanium eucolpum Haeckel, 1887, p. 1322, pl. 73, fig. 4 ]

Pterocanium praetextum (Ehrenberg) eucolpum Haeckel, Nigrini, 1967, p. 70, pl. 7, fig. 2

DESCRIPTION

"Similar to Pterocanium praetextum praetextum, but differing from it in the following respects: (1) thorax more rounded, less like a biretta; (2) apical horn 3-bladed; (3) abdomen usually less well developed; and (4) shell generally thinner.

"P. praetextum eucolpum is found only in middle latitudes (30 degrees -45 degrees S) and seems to be the cool water form of P. praetextum praetextum which is found exclusively in warm water areas." (from Nigrini, 1967).

DIMENSIONS "Length of apical horn 18-45 microns; of cephalis 18-27 microns; of thorax 36-63 microns; of abdomen up to 54 microns; of feet 72-136 microns. Breadth of cephalis 18-27 microns; of thorax 72-90 microns." (from Nigrini, 1967).

Plate 23, figure 3

N44

RECENT DISTRIBUTION

1. Nigrini, 1967, fig. 36; "Indian Ocean occurrences - P. praetextum eucolpum is abundant (5% to 15% of the described population) south of 35 degrees S, but does not occur in low latitude samples. It appears to be a reliable and potentially useful member of the middle latitude assemblage."

2. Nigrini, 1970, fig. 25; belongs to a transitional assemblage derived by recurrent group analysis of North Pacific samples, but does occur rarely in tropical sediments.

3. Lozano, 1974, see P. praetextum praetextum.

4. Molina-Cruz, 1975; see P. praetextum praetextum.