N39

Pterocanium korotnevi (Dogiel)

Pterocorys korotnevi Dogiel, Dogiel and Reshetnyak, 1952, p. 17, fig. 11

Pterocanium korotnevi (Dogiel), Nigrini, 1970, p. 170, pl. 3, figs. 10,11

DESCRIPTION

"Thorax in the form of a cupola or a perforated pot with rounded, small pores of uneven size. Three massive, faceted and slightly convex (outward) basal spines extending from the lower rim of the cupola. The spines extend from the rim of the cupola at an angle of 120 degrees to each other. The length of the basal spines somewhat exceeds the combined length of the cupola and the apical spine. The surface of the cupola is nodose with short conical protrusions. From the lower margin of the thorax to the base of the cephalic, there are 5-6 horizontal rows of pores; these pores decreasing in size in the direction of the mouth aperture. The cephalis has the form of a small dome-like, reticulate superstructure above the cupola of the thorax. This superstructure consists of pores which are larger than those on the thorax; they are triangular or tetragonal instead of rounded, with narrow bars between them. The number of pores on the cephalis is small, obviously not over 6-8. From the apex of the cephalic arises an apical spine; it is smooth, massive and somewhat shorter than the basal spines. Height 0.26, width 0.09mm. We found one specimen in a sample from a depth of 500-200m.

"Remark. While further studying the material from the Bering Sea, this species was encountered at the same depths, from 500 to 200m. In many of the discovered specimens the ventral section, i.e. the abdomen, was clearly expressed. The latter forms on its slightly inflated adoral belt a fine delicate net of polygonal mesh." (from Dogiel and Reshetnyak, 1952; translation courtesy W.R. Riedel).

Subsequent investigators (Ling et al., 1971; Sachs, 1973) have not observed an abdomen on this species.

DIMENSIONS

"Maximum width of cephalic 32-40 microns, of thorax 65-80 microns; maximum length of apical horn 50-75 microns." (from Ling et al., 1971).

"cephalic width: 26 +/- 3 microns; thoracic width: 83+/- 5 microns; length of cephalis plus thorax: 73+/- microns. (Average for 16 specimens from 3 samples)." (from Sachs, 1973).

REMARKS

1. See Nigrini (1970) for explanation of generic assignment.

Plate 23, figures la,b

N40

RECENT DISTRIBUTION

1. Nigrini, 1970, fig. 27; belongs to a subarctic assemblage derived by recurrent group analysis of North Pacific sediments.

2. Ling et al., 1971; "The species is found only sparsely in the Bering Sea samples."

3. Sachs, 1973, Code 1N; "Maximum abundance in the surface study in NE part of region (7%); common accessory elsewhere. Maximum abundance in core V21-137 10-35% in interval from 30-90 cm. These anomalous concentrations forced exclusion of the species from data analyses."

4. Molina-Cruz, 1975, Code N26; not used in factor analysis of southeast Pacific assemblages, cf. Appendix 10 for percent N26 at each station; "rare in this study".