radiolaria - rads_cat - Sethocyrtis chrysallis

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Sethocyrtis chrysallis

Citation: Sethocyrtis chrysallis Sanfilippo & Blome 2001

Type repository: Holotype (Fig. 6j) from ODP 1051A-7H-5, 40-42 cm, in the middle Eocene Podocyrtis (Lampterium) chalara Zone (equivalent to calcareous nannofossil Zone CP14b).

Family (traditional): Theoperidae

Two-segmented shell bearing a slender conical horn. The acorn-shaped thorax varies slightly in length, and terminates in a slightly constricted aperture surrounded by a hyaline peristome. The cephalis is poreless and bears a slender, sometimes roughened, conical horn of variable length. The thoracic pores are small, closely packed, circular, uniform in size and arrangement in longitudinal rows. In the early part of its range the pores in the distal third of the thorax are somewhat larger than the proximal ones.

Measurements based on 30 specimens from 171B-1051A-8H-5, -16H-5 and -17H-2. Length (excluding horn) 125-190 µm; length of horn 50-100 µm; breadth of thorax 85-110 µm; breadth of peristome usually 12 µm. Distinguishing characters (rw): It differs from other co-occurring two-segmented forms in the arrangement of the thoracic pores and the somewhat constricted hyaline peristome. The length of the thorax is somewhat variable. In the early part of its range the distal thoracic pores are slightly larger than the proximal ones. Phylogeny (rw): Although no transitional forms have been observed, it seems clear that S. chrysallis n. sp. evolved rapidly from S. austellus n. sp. in the uppermost part of the Podocyrtis (Podocyrtoges) ampla Zone by loss of the abdominal segment.

The name is derived from the Greek noun chrysallis (feminine), chrysalis.

Equivalent to:

Sethocyrtis sp. Chen 1975, p. 459, pl. 1, figs. 4, 5; Takemura 1992, p. 747, pl. 7, figs. 14, 15; Strong et al. 1995 (in part), p. 209, fig. 11w; Takemura & Ling 1997, p. 114, pl. 1, fig. 11.
Sethocyrtis sp. A Hollis et al. 1997, p. 65, pl. 6, fig. 7.

References:

Sanfilippo, A. & Blome, C. D. (2001). Biostratigraphic implications of mid-latitude Palaeocene-Eocene radiolarian faunas from Hole 1051A, ODP Leg 171B, Blake Nose, western North Atlantic. Geological Society of London, Special Publications. 183: 185-224. gs

CATALOG OF ORIGINAL DESCRIPTIONS: Sethocyrtis chrysallis Sanfilippo & Blome 2001

Sethocyrtis chrysallis

References:

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