radiolaria - rads_cenozoic - Plannapus hornibrooki radiolaria - rads_cenozoic - Plannapus hornibrooki

Plannapus hornibrooki

Classification: rads_cenozoic -> Carpocaniidae -> Plannapus -> Plannapus hornibrooki
Sister taxa: P. hornibrooki, P. mauricei, P. microcephalus, P. sp.


Citation: Plannapus hornibrooki O'Connor 1999
taxonomic rank: species
Basionym: Plannapus hornibrooki
1989 Dicolocapsa microcephala? - Lazarus and Pallant p.362; pl.5, figs.2-3
1999 Plannapus hornibrooki - O'Connor p.7; pl.1, fig.7a-10; pl.5, fig.8a-11
2000 Plannapus hornibrooki - O'Connor p.207; pl.1, figs.10a-11b

Catalog entries: Plannapus hornibrooki

Original description: Cephalis internally spheroidal, externally hemispheroidal to inflated truncate-conical because lower part enveloped by upper thorax; surface dimpled or with low, irregular, discontinuous ridges; bearing anteriorly offset, tiny, three-bladed apical horn; pores sparse, circular to subcircular, irregular in size and distribution: vertical tube at posterior base of cephalis, generally circular in transverse section, often externally expressed as very low truncate-conical protrusion (pl. 1, fig. 7a, b, 8a, b); collar stricture generally externally visible as slight change in shell contour. Thorax truncate-ovoid; approximately same width distal ly as proximally, greatest width generally at mid-thorax; generally circular in transverse section but some specimens may be slightly laterally compressed; uppermost part envelopes lower cephalis; surface slightly rough due to dimples or low, discontinuous, irregular ridges; pores circular to subcircular, small, widely spaced, generally roughly quincuncially arranged, flush with thoracic surface; three internally distinct, externally indistinct ribs corresponding to D, LI and Lr may extend outside as tiny wings on mid to upper part of thorax; generally no marked external contour change between thorax and peristome; peristome short, often smooth (or less rough than thorax), internally cylindrical, externally inverted truncate-conical; aperture constricted; termination smooth. Internal skeletal elements consist of bars A, D, V, M, LI, Lr, ll, lr, Vbl, Vbr, arches A-Vbl, A-Vbr. Ll-Vbl, Lr-Vbr, Vbl-Vbr, ll-Ll, lr-Lr, D-ll, D-lr and spines Ax, Vs (text-fig. 2; pl. 1, fig. 10); A extends freely upwards from M to wall of cephalis and extends outside as apical horn; V extends obliquely upwards from M to bars Vbl and Vbr; short Vs extends into vertical tube from intersection of V, Vbl and Vbr; Ax reduced to a node; D extends obliquely downwards from M to join thoracic wall, becomes rib, may extend outside as small wing; Ll and Lr extend laterally to arches then continue obliquely downwards to join thoracic wall, become ribs, may extend outside as small wings; ll and lr extend laterally to join cephalic wall; arches A-Vbl and A-Vbr fused to cephalic wall, curve downwards from intersection of A with cephalis to join bars Vbl and Vbr at cephalic wall; bars Vbl and Vbr and arches Ll-Vbl, Lr-Vbr, ll-Ll, lr-Lr, D-ll, D-lr form ring at base of cephalis; arch Vbl-Vbr forms lower base of vertical tube. 


Biogeography and Palaeobiology

Biostratigraphic distribution

Geological Range:
Last occurrence (top): within Paleogene Period (23.03-66.04Ma, top in Chattian stage). Data source: Lazarus et al. 2015 - "P age group"
First occurrence (base): within Paleogene Period (23.03-66.04Ma, base in Danian stage). Data source: Lazarus et al. 2015 - "P age group"

Plot of occurrence data:


Lazarus, D & Pallant, A (1989). Oligocene and Neogene Radiolarians from the Labrador Sea, ODP Leg 1051. Proceedings of the Ocean Drilling Program, Scientific Results. 105: 349-380. gs

O'Connor, B. (1999b). Radiolaria from the Late Eocene Oamaru Diatomite, South Island, New Zealand. Micropaleontology. 45(1): 1-55. gs

O'Connor, B. (2000). Stratigraphic and geographic distribution of Eocene - Miocene Radiolaria from the southwest Pacific. Micropaleontology. 46(3): 189-228. gs


Plannapus hornibrooki compiled by the radiolaria@mikrotax project team viewed: 2-3-2024

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