radiolaria - rads_cenozoic - Druppatractus irregularis radiolaria - rads_cenozoic - Druppatractus irregularis

Druppatractus irregularis

Classification: rads_cenozoic -> Actinommidae -> Stylosphaeridae -> Druppatractus -> Druppatractus irregularis
Sister taxa: D. hastatus, D. irregularis, D. nanus, D. pyriformis, D. variabilis, D. sp.


Citation: Druppatractus irregularis Popofsky 1912
Rank: species
Basionym: Druppatractus irregularis
1912 Druppotractus [sic.] irregularis - Popofsky p. 114-115; text figs 24-26
1966 Druppatractus irregularis - Benson p. 180-182; pl. 7, figs. 7-11
1983 Druppatractus irregularis - Benson p. 502
Taxonomic discussion: Popofsky 1912

Catalog entries: Druppatractus irregularis

Original description: Innere Schale unregelmäßig, birnenförmig, am einen Ende dünner und schlanker, am anderen Ende verdickt, auch etwas exzentrisch gelagert; der dünnere Pol ist der äußeren Schale beträchtlich näher als alle übrigen Schalenteile. Die Poren dieser inneren Schale sind kreisförmig, verschieden groß, die Gitterbalken werden halb so dick wie die Poren. Auf der Oberfläche dieser Schale erheben sich 8 bis 10 Stacheln mit etwas breiterer Basis, dieselben sind meist dreikantig. An den beiden Polen stehen die kräftigeren und breiteren Polstacheln, die meist nicht wie die anderen Stacheln radial, sonst etwas schief gestellt sind und auch etwas gebogen sein können. Der Stachel am dünneren Pol ist nicht so kräftig als die am dickeren Ende der birnenförmigen Innenschale. Alle Stacheln außer den beiden Polstacheln endigen in der äußeren Schale, selten (siehe Textfigur 25, Stacheln unten links), setzen sie sich über dieselbe als ein kleiner Dorn fort. Die äußere Schale regelmäßig ellipsoid, mit polygonalen, unregelmäßigen, etwa gleich großen Poren (Textfigur 25) oder auch mit kreisförmigen, annähernd gleichgroßen Maschen (Textfigur 26), die aus den polygonalen durch Ausrundung der Ecken entstanden zu denken sind. Die Polstacheln setzen sich über diese äußere Schale in Gestalt von kurzen dreiseitigen Pyramiden fort, und zwar zeigt der kleinere Polstachel auch außerhalb die kürzeste Pyramide.


Published descriptions

Benson 1966 - Druppatractus irregularis

An inner pear-shaped shell and outer ellipsoidal shell as in Druppatractus cf. pyriformis but with fewer and thinner three-bladed, radial beams joining them (10-15).Two heavier polar beams generally coaxial with the major shell axis and each continuous with a polar spine; polar spines of unequal length but in contrast to Druppatractus cf. pyriformis the greater polar spine continuous with beam arising from pole opposite the one with the small lobe of the pear-shaped inner shell; lesser polar spine absent in many specimens; lesser polar spine, its associated beam, and the major axis of the inner shell (including the small lobe) displaced in many specimens as much as 30-40 from the major axis and coaxial greater polar spine of the outer shell; accessory spines continuous outward from the thinner radial beams generally absent, but 1-5 short, three-bladed spines present in a few specimens and generally located around one or the other pole of the major axis. Outer shell thin-walled, relatively smooth but generally with short thorns at the nodes of the intervening bars, with small, subequal, subregularly arranged polygonal to subpolygonal or subcircular pores, 12-18 (generally 15) on half the minor circumference, without polygonal frames. Inner shell with thin wall, smooth surface, with subequal, hexagonally arranged polygonal pores, 7-8 on half the minor circumference.

Measurements: based on 30 specimens from stations 27, 34, and 71: major diameter of outer shell 69-92 µm, of inner shell 38-46 µm; minor diameter of outer shell 59-84 µm, of inner shell 30-34 µm; length of greater polar spine 4-33 µm, of lesser polar spine (when present) 6-22 µm, of accessory radial spines 2-21 µm.

Remarks: The cortical shell of this species is much less variable in size and thickness of its wall than in Druppatractus cf. pyriformis. The presence of the pear-shaped medullary shell is a unique and constant feature in both species and was not observed in any other species from the Gulf.

Distribution: This species is less abundant in the Gulf than D. cf. pyriformis. It is common to rare as far north as station 130 but is rare or absent farther north. It is absent at stations 133, 191, 203, 208, and 214.Its highest frequency was observed at stations 71 (4.4%) and 95 (4.0%) where at each it is the fifth most abundant species. It does not increase significantly in areas of upwelling; in fact, at station 90, it is very rare in contrast to the high frequency of the preceding species, but at station 91 it is almost common. Its greater frequency in the southern half of the Gulf and its decrease toward the north indicates its greater affinity for the tropical Pacific water masses than for those of higher temperature and salinity. Its distribution may also be controlled, in part, by upwelling, but the available data are too meager to make any conclusions regarding this. Popofsky (1912, p. 115) reported this species from the western tropical part of the Indian Ocean and from the tropical part of the central Atlantic Ocean. It, therefore, appears to be confined to the tropical parts of the world's oceans, unless the pear-shaped shell illustrated by Bailey (1856, Pl. 1, fig. 29) and reported from a high latitude is identical with this species, not with Druppatractus cf. pyriformis. \ From: Benson, 1966, p. 180-182; pl. 7, figs. 7-11:Druppatractus irregularis PopofskyDruppotractus [sic.]irregularis Popofsky, 1912, Deutsche Tiefsee-Exped , vol 13, pp 114-115, text figs 24-26.

Biogeography and Palaeobiology

Biostratigraphic distribution

Geological Range:
Last occurrence (top): Extant. Data source: Lazarus et al. 2015 - "R age group"
First occurrence (base): within Quaternary Period (0-2.59Ma, base in Gelasian stage). Data source: Lazarus et al. 2015 - "R age group"

Plot of occurrence data:


Benson, R. N. (1966). Recent Radiolaria from the Gulf of California. Thesis, Minnesota University. 1-577. gs

Benson, R. N. (1983). Quaternary radiolarians from the Mouth of the Gulf of California, Deep Sea Drilling Project Leg 65. Initial Reports of the Deep Sea Drilling Project. 65: 491-523. gs

Popofsky, A (1912). Die Sphaerellarien des Warmwassergebietes. Deutsche Sudpolar-Expedition 1901-1903. 13(5): 73-159. gs


Druppatractus irregularis compiled by the radiolaria@mikrotax project team viewed: 29-11-2023

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