Journal of Foraminiferal Research, v. 15, no. 2, p. 138-140, pl. 1, April 1985
ABDITODENTRIX, A NEW FORAMINIFERAL GENUS IN
R. TIMOTHY PATTERSON
Department of Earth and Space Sciences, University of California, Los Angeles, CA 90024
Abditodentrix, a new genus of the Bolivinitidae, dif-
fers from other genera of the family by its distinct
truncate margin, reticulate ornamentation, and re-
duced toothplate. The type species of the new genus is
Abditodentrix asketocomptella, n. sp.
Based on such morphologic features as apertural ori-
entation, nature and presence, or absence, of a tooth-
plate, and chamber arrangement, genera of the family
Bolivinitidae have been variously defined (Loeblich
and Tappan, 1964; Tappan and Loeblich, 1982; Sellier
de Civrieux, 1976; and others). Among the benthic
foraminifera in Recent to Pliocene samples from the
Rio Grande Rise in the southwest Atlantic Ocean is a
comparatively common species of the Bolivinitidae
whose characteristics exclude it from existing genera.
Thus a new genus is required for placement of the
Materials used for this study were from five core
levels of DSDP Site 357 (Leg 39) on the Rio Grande
Rise, southwest Atlantic Ocean; latitude 30'OO.25'S.,
longitude 35'33.59'W. The core levels were:
1. Pleistocene; Core I, Section I, 80-86 em.
2. Pleistocene; Core I, Section 2, 80-86 em.
3. Pleistocene; Core I, Section 3, 80-86 em.
4. Pleistocene; Core 1, Section 4, 80-86 em.
5. Pliocene, Core I, Section 5, 80-86 em.
Approximately 100 specimens from five core levels
at a single locality were examined variously in reflected
light, polarized transmitted light, and with a scanning
electron microscope to examine the test surface and
perforations, apertural form and position, nature of
the apertural toothplate and test interior in a half sec-
tioned specimen, and the orientation of the calcite crys-
tal lattice in a crushed specimen.
For half sectioning, a single specimen was embedded
in Lakeside 70 and carefully ground on 15-micron
dry emery paper until the inner structure of the test
was exposed. The specimen was then immersed in al-
cohol overnight to dissolve the Lakeside 70, mounted
on a plug, coated with gold, and illustrated with the
scanning electron microscope. Another specimen was
crushed between a glass slide and cover slip with (D
1.550) immersion oil and examined in polarized light
to determine the wall microstructure.
Scanning electron micrographs of the half-sectioned,
and other selected specimens were taken with an ISI
Super-111A Scanning Electron Microscope, using Po-
laroid NP 55 film.
The holotype, figured paratypes and unfigured para-
types are deposited in the National Museum of Natural
History, Washington, D.C.
Suborder ROTALIINA Delage and Herouard, 1896
Superfamily BULIMINACEA Jones, 1875
Family BOLIVINITIDAE Cushman, 1927
Genus Abditodentrix, n. gen.
Type species. Abditodentrix asketocomptella. n. sp.
Diagnosis. A genus of Bolivinitidae with flattened
sides and truncate margins, heavy reticulate surface
ornamentation, biserially arranged chambers, and bas-
al elliptical aperture, with a toothplate.
Description. Test free, elongate rectangular in sec-
tion, sides flattened, the distinctly angular lateral
chamber margins producing a serrate test outline;
chambers arranged biserially throughout; sutures com-
monly deeply incised; wall calcareous, hyaline, opti-
cally radial, distinctly perforate with medium-sized
pores; surface highly ornamented with a network of
elevated reticulations, apertural face less ornamented;
1-9 Abditodentrix asketocomptella, n. gen. I. Apertural view of paratype (USNM 383102) showing prominent lip and depressed toothplate,
x 500. DSDP site 357, core I, section 1,80-86 cm; Recent/Pleistocene. 2, 9. Exterior of holotype (USNM 383104). 2, enlargement illustrating
high degree of ornamentation due to lamellar thickening, and showing apertural lip, x 500. 9, entire test showing characteristic serrated and
truncated margins, x 200. DSDP site 357, core I, section 2, 80-86 cm; Recent/Pleistocene. 3. Edge view of para type (USNM 383105) showing
reduced ornamentation on apertural face, x 500. DSDP site 357, core I, section 5, 80-86 cm; Pliocene. 4, 7. Exterior view of para type (USNM
383106).4, enlargement showing little secondary ornamentation, and highly incised sutures, x 500.7, entire test showing truncate margin and
little of the characteristic surface ornamentation, x200. DSDP site 357, core I, section 3, 80-86 cm; Recent/Pleistocene. 5. Lateral section
NEW FORAMINIFERAL GENUS IN BOLIVINITIDAE
of para type (USNM 383103) illustrating toothplate arrangement at aperture and in previous chambers, x300. DSDP site 357, core I, section
2, 80-86 cm; Recent/Pleistocene. 6. Paratype (USNM 383102) showing highly perforate areas where lamellar thickening of reticulations is
minor, x 500. DSDP site 357, core I, section I, 80-86 cm; Recent/Pleistocene. 8. Paratype (USNM 383102) showing an intermediate level
of secondary ornamentation, as well as the typical serrate and truncate margins, x200. DSDP site 357, core I, section 1,80-86 cm; Recent/
aperture basal, elliptical, perpendicular to suture, with
bordering lip on one side, free part of toothplate re-
duced and not projecting from aperture, enfolded in-
ternally, one side of toothplate terminating midway
through the chamber interior, those of successive
chambers alternating in direction.
Derivation of name. From the Latin, abditus, hid-
den, concealed, + dens. dent is, tooth, + trix, action
and agency, with reference to the depressed toothplate
in this genus. Gender feminine.
Remarks. Bolivinita differs from Abditodentrix in
being larger, with more truncate and keeled margins,
and in lacking surface ornamentation. The two genera
are similar in apertural arrangement although the ap-
erture of Bolivinita is somewhat larger and its tooth-
plate tends to project farther. Abditodentrix also is
somewhat more coarsely perforate than Bolivinita. Bo-
livina differs from the present genus in its toothplate
projecting through the aperture and bisecting the slit-
like opening. Abditodentrix also has a more truncate
margin than Bolivina. In ornamentation Bolivina is
either smooth, striate, or costate, whereas Abditoden-
trix has a complex network of elevated reticulations
that are somewhat independant of individual cham-
bers. Latibolivina displays a similar network of reti-
culations, but they tend to be more regular in elevation
and pattern than those of Abditodentrix. Latibolivina
also lacks the truncate margin of Abditodentrix.
Abitodentrix asketocomptella, n. sp.
Diagnosis. A species of Abditodentrix with flattened
sides and truncate margins, heavy primary and sec-
ondary reticulate surface ornamentation, biserially ar-
ranged chambers, and a basal elliptical aperture, with
Description. Test free, rectangular in section, sides
flattened, the angular lateral chamber margins pro-
ducing a serrated test outline; biserial chamber ar-
rangement; sutures moderate to deeply depressed, at
about 45° to the longitudinal axis; wall calcareous, hya-
line, optically radial; medium degree of perforation,
pores concentrated in areas of reduced ornamentation
except on apertural face; surface highly ornamented
with a network of elevated reticulations, ornamenta-
tion reduced on apertural face; aperture basal, ellipti-
cal, perpendicular to suture, aperturallip restricted to
one side, toothplate reduced and not projecting from
the aperture, enfolded internally, one side of tooth plate
terminating midway through the chamber interior,
those of successive chambers alternating in direction.
Derivation of name. From the Latin, asketos, curi-
ously wrought, + comptus, compus, ornamented,
adorned, + ella, diminutive, with reference to the
highly ornamented test.
Measurements. Maximum length, 240 µm; ;maxi-
mum width, 120 µm.
Types and occurrences. Recent, Pleistocene and
Pliocene. Holotype (USNM 383104), figured paratypes
(USNM 383102-383103, 383105-383106), and un-
figured paratypes (USNM 383101) from DSDP site
357 (Leg 39); Rio Grande Rise in the southwest At-
lantic Ocean; latitude 30°00.25'S., longitude
35°33.51 'W.; Core I, Section I, 80-86cm; Recent/
Pleistocene. Other figured and unfigured paratypes are
from Core 1, Section 2, 80-86 em.; Core I, Section I,
Section 3, 80-86 cm.; Core 1, Section 4, 80-86 cm.;
all Recent to Pleistocene and from Core 1, Section 5,
80-86 em. of Pliocene age.
Remarks. In young specimens the ornamentation is
restricted to areas near the sutures. As specimens age
a secondary phase of ornamentation occurs with the
test becoming increasingly encrusted with reticula-
tions. The heavy ornamentation and truncate margins
ofthis species, as well as the reduced toothplate, readily
differentiate it from species of Bolivina. Abditodentrix
asketocomptella differs from species of Bolivinita by
the absence of ornamentation and distinctive keeled
truncate margins of the latter. The extreme depression
of the margins of some specimens of A. asketocomp-
tella is similar to Bolivina cf. lepida Sliter as figured
by Sellier de Civrieux (1976, pl. 7, fig. 8). However,
B. cf. lepida is much more coarsely perforate than A.
asketocomptella. In addition B. cf. lepida is less or-
namented and lacks a truncated margin. Sellier de Civ-
rieux did not provide an apertural view. The orna-
mentation of A. asketocomptella somewhat resembles
that of Latibolivina anastomosa (Finlay). However, the
reticulations of A. asketocomptella are less regular than
those of L. anastomosa. Latibolivina anastomosa also
lacks the truncate margin of A. asketocomptella.
This research was supported by a Canadian Natural
Sciences and Engineering Research Council Postgrad-
uate Scholarship. Samples from the Deep Sea Drilling
Project were supplied through the assistance of the
National Science Foundation. National Science Foun-
dation Grant EAR-8306170 to Alfred R. Loeblich,
Jr., and Helen Tappan provided support and use of
the scanning electron microscope. I would also like to
thank A. R. Loeblich, Jr., for assistance in preparing
the section and the scanning electron micrographs, and
HT for critically reviewing the manuscript.
LOEBLlCH, A. R., JR., and TAPPAN, H., 1964, Sarcodina, chiefly
"Thecamoebians" and Foraminiferida, in Moore, R. C. (ed.),
Treatise on Invertebrate Paleontology, Part C, Protista 2: Geo-
logical Society of America and University of Kansas Press, 900 p.
TAPPAN, H., and LOEBLlCH, A. R., JR., 1982, Granuloreticulosa,
in Parker, S. B. (ed.), Synopsis and Oassification of Living Or-
ganisms, v.1: McGraw-Hill Book Company, New York, p. 527-
SELLIERDEOVRIEUX, J. M., 1976, Estudio sistematico y ecologico
de las Bolinitidae recientes de Venezuela: Cuademos Oceano-
graphicos, Universidad de Oriente, no. 5, p. 3-101.
Received August 21, 1984
Accepted August 27, 1984