N33

Dictyophimus crisiae Ehrenberg

Dictyophimus crisiae Ehrenberg, 1854a, p. 241

Dictyophimus crisiae Ehrenberg, Nigrini, 1967, p. 66, pl. 6, figs. 7a, b

?Pterocorys (?) hirundo Haeckel, Petrushevskaya, 1967, p. 115, fig. 67, IV-V (partim.)

Pterocorys hirundo Haeckel, Ling, et al., 1971, p. 715, pl. 2, figs. 8, 9 (partim.)

DESCRIPTION

"Cephalis hemispherical with small closely spaced pores or pits (probably representing infilled pores). Inside cephalis, both apical and vertical spines are free of the shell wall. Externally, apical spine forms a cylindroconical horn which may be up to 3 times the length of the cephalis; vertical spine forms a short, much more delicate horn. In some specimens the dorsal spine is also external, and usually additional by-spines occur on the cephalis and upper thorax. Collar stricture indistinct.

"Thorax conical, rather than thick-walled, with large subcircular to subangular pores increasing in size distally; bars relatively narrow. Strong thoracic ribs become external just above the lumbar stricture and are prolonged into 3 solid cylindrical or 3-bladed wings as long to 3 times as long as thorax, tapering to a point distally. Wings diverge freely, forming an extension of the conic line of the thorax.

"Abdomen thinner-walled, cylindrical, varying in state of development, and having pores similar to those on thorax. No definite termination." (from Nigrini, 1967).

DIMENSIONS "Length of apical horn 18-72 microns; of cephalis 18-27 microns; of thorax 45-63 microns; of abdomen up to 81 microns. Maximum breadth of cephalis 23-32 microns; of thorax 63-100 microns." (from Nigrini, 1967).

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

2. There has been some confusion between this species and a form referred to as Pterocorys hirundo Haeckel. The form here described as Dictyophimus crisiae Ehrenberg is unusually robust. Even incomplete specimens are thick-walled. The appendages are definitely wings, not feet and project from the thorax above the lumbar stricture.

Plate 22, figures 1a,b

N34

RECENT DISTRIBUTION

1. Nigrini, 1967, fig. 34; "Indian Ocean occurences - D. crisiae is sparsely distributed in both low and middle latitudes, being slightly more abundant in the latter (up to 5% of the described population)."

2. Ling, et al., 1971; The specimens shown in plate 2, figures 8 and 9 belong to D. crisiae. The specimen in plate, figure 10 may belong to D. hirundo. Ling et al. found these species to be sparsely distributed in the Bering Sea.

3. Sachs, 1973, Code 6N (Pterocorys hirundo); "In the surface study, this species was ubiquitous but did not account for more than 2% of the fauna, except for two SE stations: strewn sample [005] from V21-175, and samples [026] (strewn) and [044] (settled) - from RC11-185."

4. Molina-Cruz, 1975, Code N29 (Pterocorys hirundo); used in factor analysis of southeast Pacific assemblages; cf. Appendix 10 for percent N29 at each station.