CATALOG OF ORIGINAL DESCRIPTIONS: Acarinina planodorsalis Fleisher 1974

This page provides data from the catalog of type descriptions. The catalog is sorted alphabetically. Use the current identification link to go back to the main database.

Higher levels: pf_cat -> A -> Acarinina -> Acarinina planodorsalis
Other pages this level: << < A. discors, A. falsospiralis, A. inaequiconica, A. indolensis, A. intermedia, A. interposita, A. kiewensis, A. mattseensis alticonica, A. mcgowrani, A. microsphaerica, A. multicamerata, A. multiloculata, A. pentacamerata acceleratoria, A. pentacamerata camerata, A. pentacamerata erevanensis, A. planodorsalis, A. praecursoria, A. primitiva, A. proxima, A. pseudosubsphaerica, A. pseudotopilensis, A. punctocarinata, A. quadratoseptata, A. rotundimarginata, A. rugosoaculeata, A. subintermedia, A. subpentacamerata, A. tadjikistanensis djanaensis, A. triplex, A. umbilicata, A. vedica,

Acarinina planodorsalis

Citation: Acarinina planodorsalis Fleisher 1974
Rank: Species
Type age: early Middle Eocene (P .11; Globigerinatheka sub conglobata subconglobata Zone of Bolli, 1972, = Globigerapsis kugleri Zone of Bolli, 1966).
Type sample and level: Hole 219, Core 29, Section 4, 52 54 cm
Holotype Repository: Washington; USNM

Linked specimens: USNM-211391 USNM-211392 USNM-211393 USNM-211390

Current identification/main database link: Pearsonites broedermanni (Cushman & Bermudez 1949)

Original Description
"The small to medium-sized planoconvex test consists of at least 11 chambers arranged in a low trochospire, with 6 to 8 chambers in the final whorl. The ventral cameral wall consists of short pseudospines whose interconnected bases separate common and relatively large pores. The development of pseudospines is most pronounced around the umbilicus, but these fetures are poorly developed or absent on the dorsal surface (fig.2) except over the obscured early whorls. The spiral surface is nearly flat, but the early chambersform a broad low projection. The dorsal sutures are strongly depressed and curved, particularly in the distant portion of each suture. The anterior margin of each chamber projects above the posterior region of the following chamber, giving a slightly imbricate appearance to the dorsal surface. The chambers and sutures, as a result, are quite distinct in dorsal view, particularly in the final whorl. The slightly lobate periphery is subacute in the early portions of the final whorl and rounded on the last few chambers. The ventral surfaces of each chamber slope gradually from the periphery to the edge of the umbilicus, but the steepness of inclination increases throughout the final whorl. Ventral sutures are straight and somewhat depressed, especially near the umbilicus, where they appear as narrow, deeply incised channels. The rounded umbilical shoulders are roughened by the increased development of coarse pseudospines. The umbilicus varies from broad to narrow, but is generally distinct. The aperture is a low arch near the center of the base of the apertural face. No distinct apertural lip is present.

Size: Maximum diameter of the holotype is 0.35 mm; axial elevation is 0.21 mm.

Etymology: The species name refers to the flattened dorsal surface

Extra details from original publication
Remarks: A. planodorsalis is similar in form to A. nicoli (Martin), but differs in having more chambers per whorl and more distinct dorsal sutures. It also resembles A. mattseensiswartstein ensis from which it appears to have evolved. It may be separated from this latter form by its less elevated ventral surface, flatter dorsal side and more distinct dorsal sutures, and the channelled ventral sutures in the umbilical region.


Fleisher, R. L. (1974a). Cenozoic planktonic foraminifera and biostratigraphy, Arabian Sea, Deep Sea Drilling Project, Leg 23A. Initial Reports of the Deep Sea Drilling Project. 23: 1001-1072. gs :: ::


Acarinina planodorsalis compiled by the pforams@mikrotax project team viewed: 10-7-2020

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