Lamprocyrtis neoheteroporos


Classification: rads_cenozoic -> Pterocorythidae -> Lamprocyrtis -> Lamprocyrtis neoheteroporos
Sister taxa: L. daniellae, L. heteroporos, L. neoheteroporos, L. nigriniae, L. sp.

Taxonomy

Citation: Lamprocyrtis neoheteroporos Kling 1973
Rank: species
Basionym: Lamprocyrtis neoheteroporos
Taxonomic discussion: Kling 1973 p.639 pl.5 figs.17-18, pl.15 figs.4-5; Goll 1980 p.436 pl.3 fig.11; Alexandrovich 1989 (ODP 111 SR) pl.2 fig.4

Catalog entries: Lamprocyrtis neoheteroporos

Original description: Two segmented forms with cephalis [three-lobed,] hemispherical to cylindrical, commonly open; with a stout three-bladed apical horn and usually one or more accessory spines; with circular to elliptical, irregularly arranged pores. Collar stricture indistinct. Thorax proximally conical, distally cylindrical to slightly inflated; circular to elliptical or irregular pores, longitudinally aligned, increasing in size distally, becoming two or more times as large along a horizontal discontinuity as in L. heteroporos. Smaller pores may again appear near mouth. Although early specimens show a slight, gentle indentation of the wall at this discontinuity, there is no internal stricture or septal ring separating two segments. Mouth, sometimes slightly constricted, surrounded by irregular row of small teeth; a weak peristome seldom developed. Later specimens become smaller and more inflated.

Based on 15 specimens. Maximum width 74-90 µ, length from top of cephalis 100-130 µ, proximal pore diameter 2-14 µ, (average near upper value), distal pore diameter 6-28 µ (average near upper value). Distinguishing characters (rw): The pores in the proximal part of the postcephalic shell are small, and distally they are two to three times as large, the change occurring abruptly as at an intersegmental boundary which is however not marked by an internal stricture. (Riedel and Sanfilippo, 1978a)

This species is distinguished from L. heteroporos by the absence of a lumbar constriction with an internal septal ring. It differs from L. nigriniae in having a transverse discontinuity across which the pore size differs by a factor of two or more. (Sanfilippo et al., 1985) Phylogeny (rw): L. neoheteroporos arose from L. heteroporos, and evolved into L. nigriniae. See also discussion under Phylogeny of L. heteroporos
Remarks on original description: The shell is two-segmented, but shows evidence of its three-segmented ancestor by an abrupt increase in pore size (by a factor of two or more) between the upper and lower parts of the present thorax. The species varies from a compact, small (100 microns in length) form with heavy bars between pores, to a larger form (140 microns in length) with more open lattice and lighter bars. (Sanfilippo et al., 1985)

Description

Biogeography and Palaeobiology

Biostratigraphic distribution

Geological Range:
Last occurrence (top): within Neogene Period (2.59-23.03Ma, top in Piacenzian stage). Data source: Lazarus et al. 2015 - "N age group"
First occurrence (base): within Neogene Period (2.59-23.03Ma, base in Aquitanian stage). Data source: Lazarus et al. 2015 - "N age group"

Plot of occurrence data:

References:

Alexandrovich, J. M. (1989). Radiolarian biostratigraphy of ODP Leg 111, Site 677, eastern equatorial Pacific, late Miocene through Pleistocene. Proceedings of the Ocean Drilling Program, Scientific Results. 111: 245-262. gs V O

Goll, M. R. (1980). Pliocene-Pleistocene radiolarians from the East Pacific Rise and the Galapagos spreading center, Deep Sea Drilling Project Leg 54. Initial Reports of the Deep Sea Drilling Project. 54: 425-453. gs

Kling, S. A. (1973). Radiolaria from the eastern North Pacific, Deep Sea Drilling Project, Leg 18. Initial Reports of the Deep Sea Drilling Project. 18: 617-671. gs


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Lamprocyrtis neoheteroporos compiled by the radiolaria@mikrotax project team viewed: 15-6-2021

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