A new integrated morpho- and molecular systematic classification of Cenozoic radiolarians (Class Polycystinea) - suprageneric taxonomy and logical nomenclatorial acts
Author
Suzuki, Noritoshi
Author
Caulet, Jean-Pierre
Author
Dumitrica, Paulian
text
Geodiversitas
2021
2021-07-08
43
15
405
573
journal article
5275
10.5252/geodiversitas2021v43a15
a8353504-9387-42cf-8d81-8ecacbe9bd90
1638-9395
5101757
urn:lsid:zoobank.org:pub:DC259A19-9B35-4B33-AD9F-44F4E1DA9983
Family
EUCHITONIIDAE
Stöhr, 1880
sensu
Suzuki emend. herein
Euchitonida
Stöhr, 1880: 86
[as a subfamily]. —
Haeckel 1882: 460
[as a tribe];
Haeckel 1887: 484
, 516 [as a subfamily]. —
Wisniowski 1889: 685
[as a subfamily]. —
Schröder 1909: 43
[as a subfamily].
Ommacampida
Haeckel, 1887: 392
[as a subfamily].
Euchitoninae [
sic
] –
Clark & Campbell 1942: 46
(= Euchitoniinae);
Campbell & Clark 1944b: 17
. —
Chediya 1959: 136
. —
Tan & Tchang 1976: 246-248
. —
Tan 1998: 219
. —
Tan & Chen 1999: 217
. —
Amon 2000: 49
.
Ommatocampinae
Campbell, 1954
: D76. —
Chediya, 1959: 119
.
Monaxoniinae
Campbell, 1954
: D76.
Euchitoniidae
–
Campbell 1954
: D86. —
Nakaseko & Sugano 1976: 125
. —
Kozur & Mostler 1978: 134-135
(
sensu
emend.
). — Petrushevskaya 1979: 112-113 (
sensu
emend.
). —
Matsuzaki
et al.
2015: 18-19
.
Euchitoniinae –
Campbell 1954
: D86. —
Kozur & Mostler 1978: 135-136
. — Petrushevskaya 1979: 113 (
sensu
emend.
).
Myelastrinae Riedel, 1971: 654. —
Kozur & Mostler 1978: 153
.
Chitonastrinae
Kozur & Mostler, 1978: 136
[
nomen dubium
].
Myelastridae
–
Takahashi 1991: 87
. —
De Wever
et al.
2001: 160-161
. —
Afanasieva
et al.
2005
: S284. —
Afanasieva & Amon 2006: 127
.
Euchitonidae [
sic
] –
Amon 2000: 48-49
(=
Euchitoniidae
).
TYPE
GENUS. —
Euchitonia
Ehrenberg, 1861b: 831
[
type
species by subsequent monotypy:
Euchitonia furcata
Ehrenberg, 1873a: 308
] = junior subjective synonym of
Dictyocoryne
Ehrenberg, 1861b: 830
[
type
species by subsequent designation (
Haeckel 1887: 591
):
Dictyocoryne profunda
Ehrenberg, 1873a: 307
].
INCLUDED
GENERA. —
Amphicraspedum
Haeckel, 1882: 460
(=
Amphicraspedon
with the same
type
species;
Amphirrhopella
n. syn.
). —
Dictyocoryne
Ehrenberg, 1861b: 830
(=
Dictyocorynula
with the same
type
species;
Dictyastrum
synonymized by
Matsuzaki
et al.
2015: 19
,
Dictyastrella
,
Euchitonia
,?
Hymenastromma
,
Rhopalodictya
,
Rhopalodictyum
synonymized by
Ogane
et al.
2009a: 89
),
Styla
synonymized by
Matsuzaki
et al.
2015: 19
;
Pteractis
. —
Hexinastrum
Haeckel, 1882: 461
(=
Hexalastromma
n. syn.
,
Pentalastromma
n. syn.
,
Pentinastrum
n. syn.
). —
Ommatocampe
Haeckel, 1861b: 832
(=
Ommatocampium
with the same
type
species;
Amphymenium
synonymized by
Petrushevskaya & Kozlova 1972: 527
). —
Tessarastrum
Haeckel, 1887: 547
(=
Tessarastrella
with the same
type
species;
Hagiastromma
n. syn.
,
Tessarostromma
n. syn.
). —
Tricranastrum
Haeckel, 1879: 705
(=
Dicranaster
n. syn.
,
Dicranastrum
n. syn.
,
Myelastrella
n. syn.
,
Myelastrum
n. syn.
,
Spongomyelastrum
n. syn.
,
Myelastromma
n. syn.
,
Pentophiastromma
n. syn.
,
Spongodi- cranastrum
n. syn.
,
Spongohagiastrum
n. syn.
,
Spongopentophiastrum
n. syn.
,
Spongostaurina
n. syn.
,
Tetracranastrum
n. syn.
,
Triastrum
,
n. syn.
). —
Trigonastrum
Haeckel, 1887: 538
(=
Trigonastrella
with the same
type
species;
Rhopalastromma
synonymized by
Kozur & Mostler 1978: 128
;
Chitonastromma
synonymized byKozur & Mostler 1978: 136;
Amphicraspedina
n. syn.
,
Amphirrhopoma
n. syn.
,
Dictyastromma
n. syn.
,
Monaxonium
n. syn.
,
Trigonastromma
n. syn.
).
INVALID
NAME. —
Tessarastromma
.
NOMINA
DUBIA. —
Amphirhopalum
,
Amphirrhopalium
,
Chitonastrella
,
Chitonastrum
,
Hexalastrum
,
Pentalastrella
,
Pentalastrum
,
Pentophiastrum
,
Rhopalastrella
,
Rhopalastrum
.
JUNIOR HOMONYMS. —
Spongostaurus
Swanberg,
Anderson & Bennett, 1985
(=
Spongostaurina
)
nec
Haeckel, 1882
;
Stylactis
Ehrenberg, 1873
(
Ehrenberg 1873a
=
Styla
Stechow, 1921
)
nec
Allman, 1864
.
DIAGNOSIS. — Flat shaped
Polycystinea
with circular center and arms. The central part is a convex lens-shaped structure (named “margarita”) which includes a spinose microsphere and two to three concentric convex lens-shaped crusts. The exterior structure of
the margarita
with a variable number of arms: two to four, rarely eight. Arm is constituted by a very highly dense concentric structure which resembles a spongy, a segmented structure with dividers, or superimposed cupolas. Patagium developed in some members but were differentiated from the border of the arm. Both polar sides of
the margarita
crop out or are occasionally seen covered with fine appendages.
The protoplasm can be divided in
Dictyocoryne
- and
Tricranastrum
-
types
. Typically, the spongy shell in
Dictyocoryne
is filled with a light brown endoplasm. A robust, long axoflagellum emerges from a non-walled pylome on one-side of the test. Pseudopodia radiate throughout the shell.
The margarita
portion is more transparent than the other skeletal parts. It should be noted that
Dictyocoryne truncata
(Ehrenberg)
and
Dictyocoryne profunda
Ehrenberg
exclusively possess cyanobacteria as symbionts, on the surface of the endoplasm.
Dictyocoryne muelleri
harbors algal symbionts outside the shell, as opposed to cyanobacteria. In
Tricranastrum
, the shell is occupied by a light brown endoplasm. A probable ectoplasmic membrane wraps around all skeletons including by-spines.
STRATIGRAPHIC OCCURRENCE. — early Middle Miocene-Living.
REMARKS
The central part of the
Euchitoniidae
is named by the special word: “margarita” (
Matsuoka 1992c
: pl. 2, figs 1, 5; 1993b: pl. 1, figs 4, 5;
Zheng 1994
: pl. 40, figs 4-7, 9). This is confirmed in the
Amphicraspedina
-form of
Trigonastrum
(
Takayanagi
et al.
1979
: pl. 1, figs 11, 12;
Poluzzi 1982
: pl. 20, figs 2, 3;
Wang & Yang 1992
: pl. 2, figs 26-29;
Zheng 1994
: pl. 40, figs 5, 9;
van de Paverd 1995
: pl. 51, fig. 3), the
Dictyastromma
-form of
Trigonastrum
(
Poluzzi 1982
: pl. 20, fig. 5),
Dictyocoryne
(
Poluzzi 1982
: pl.20, fig. 4), the
Euchitonia
-form of
Dictyocoryne
(
Poluzzi 1982
: pl. 20, fig. 8;
Anderson & Bennett 1985
: pl. 1, figs 1, 2, 3),
Tricranastrum
(Matsuoka 2017: figs 12.1, 12.3, 12.5- 12.7),
Ommatocampe
(
Poluzzi 1982
: pl. 20, fig. 1) and the
Pteractis
-form of
Dictyocoryne
(Matsuoka 2017: figs 15.4- 15.7;
Zheng 1994
: pl. 40, figs 4, 6, 7).
The margarita
is not covered by a patagium in the
Amphicraspedina
-form of
Trigonastrum
(
Cheng & Yeh 1989
: pl. 1, figs 7, 10),
Dictyocoryne
(
Onodera
et al.
2011
: pl. 6, fig. 8), the
Pteractis
- and
Euchitonia
-forms of
Dictyocoryne
(
Yamauchi 1986
: pl. 4, figs 10, 12),
Trigonastrum
(
Dumitrica 1973a
: pl. 10, figs 1-4). Typically,
Dictyocoryne
tends to thicken in its central part (
Cheng & Yeh 1989
: pl. 2, fig. 12) whereas the
Pteractis
-form of
Dictyocoryne
remains very flat (
Cheng & Yeh 1989
: pl. 2, figs 8, 14). Internal skeletal structure was illustrated for the
Hymenastromma
-form of
Dictyocoryne
(
Sugano, 1976
: pl. 6, fig. 3), but
Hymenastromma
appears to be similar to the
Phorticiidae
.
Molecular studies sometimes noted trouble separating
Dictyocoryne
and
Euchitonia
.
This issue has been already solved from the morphological classification’s point of view (
Ogane
et al.
2009a
;
Matsuzaki
et al.
2015
). The genus name
Euchitonia
must not no longer be applied. The existence of
Amphicraspedum
and
Hexinastrum
has been considered doubtful because no specimens identified as such have been reported. These genera are kept as valid until future confirmation of their existence.
Dictyocoryne
is one of the most examined and studied living radiolarians in ecological observations (
Matsuoka 1992
a
, 1992c,
1993
a
, 1993b, 2017;
Sugiyama & Anderson 1997a
), ecological experimental studies (
Matsuoka & Anderson 1992
;
Sugiyama & Anderson 1997a
), cytological ultrafine structures, symbionts, symbiosis (
Matsuoka 1992c
), and cytomechanics (
Anderson
et al.
1987
). Images of living forms were repeatedly illustrated for
Dictyocoryne
(
Matsuoka 1992a
: pls 1, 3; 1992c: pls 1, 3; 1992b, figs 1A, 1B, 2A, 2B; 1993a: pl. 2, figs 1, 2; 1993b: pl. 3, figs 1-4; 1994: fig. 2A; 2017: figs 13.1, 13.2; 14.1, 14.2;
Sugiyama & Anderson 1997a
: pl. 2, figs 2, 4;
Matsuoka
et al.
2001
: pl. 1, fig. 1;
Takahashi
et al.
2004
: figs 1, 2;
Yuasa
et al.
2005
: fig. 1a;
Ichinohe
et al.
2019
: fig. 2), the
Euchitonia
-form of
Dictyocoryne
(
Matsuoka 1993b
: pl. 4, figs 1, 2),
Tricranastrum
(
Yuasa
et al.
2005
: figs 1b, 1c;
Matsuoka 2007
: fig. 12; 2017: figs 12.1, 12.2), the
Pteractis
-form of
Dictyocoryne
(
Matsuoka 1992b
: figs 2C, 2D; 1993a: fig. 2.4; 1993b: pl. 4, figs 3, 4; 1994: fig. 2D; 2017: figs 15.1, 15.2) and the
Spongostaurus
-form of
Tricranastrum
(
Caron & Swanberg 1990
: fig. 3.B). Protoplasm and algal symbionts were documented by epi-fluorescent observation with DAPI dyeing and other dyeing methods for
Dictyocoryne
(
Ogane
et al.
2010
: figs 1.14-1.15; 2.14- 2.15;
Zhang
et al.
2018: 11
, figs 1, 6, 7, p. 14, figs 4, 5; p. 16, figs 2, 3), the
Euchitonia
-form of
Dictyocoryne
(
Ogane
et al.
2010
: figs 1.13, 2.13), and
Tricranastrum
(
Zhang
et al.
2018: 16
, fig. 4). An image fixed using dye method was published for
Tricranastrum
(
Aita
et al.
2009
: pl. 27, fig. 1; pl. 29, fig. 1). A cytological ultrafine-structure was observed in
Tricranastrum
(Swanberg
et al.
1985: pl. 2).
Algal symbionts of
Dictyocoryne elegans
were identified as
Gymnoxanthella radiolariae
by
Yuasa
et al.
(2016)
, the same dinoflagellate species as those of
Acanthodesmia
(
Acanthodesmiidae
,
Nassellaria
) and
Dictyopodium
(originally
Pterocanium
,
Lithochytrididae
,
Nassellaria
).
VALIDITY OF GENERA
Amphicraspedum
Amphirrhopella
is characterized by terminal spines but this character is induced by intraspecies or intraspecies variation.
Dictyocoryne
The combinations
Dictyocoryne
and
Dictyocorynula
,
Dictyastrum
and
Dictyastrella
, and
Rhopalodictyum
and
Rhopalodictya
have respectively the same
type
species. Since
Rhopalodictyum
has already been synonymized with
Dictyocoryne
(
Ogane
et al.
2009a: 89
) and
Dictyastrum
also synonymized with
Dictyocoryne
(
Matsuzaki
et al.
2015: 19
)
,
Rhopalodictya
and
Dictyastrella
are both automatically synonyms of
Dictyocoryne
. “
Styla
” is also synonymized with
Dictyocoryne
as the name of
Stylactis
by
Matsuzaki
et al.
(2015:19)
. In this context, our paper newly synonymized
Hymenastromma
with
Dictyocoryne
. As shown in the supporting image of the
Atlas
for
Hymenastromma
, the central structure is different from
Dictyocoryne
. Both these genera may be independent from each other.
The oldest available
names
are listed as
Dictyocoryne
,
Dictyastrum
,
Euchitonia
and
Rhopalodictyum
fromEhrenberg (1861b). The formal publication and years of publication for these genera have been confused due to a
nomen nudum
in
Ehrenberg (1861a)
and the mismatch of volume number as “1860” and the published year for
Ehrenberg (1861a
;
1861b
) (
Lazarus &
Suzuki 2009: 31
). The
names
Dictyocoryne
and
Rhopalodictyum
are commonly used in references but the condition of preservation and the completeness of the shell are better for the
lectotype
of
Dictyocoryne
than for
Rhopalodictyum
.
Hexinastrum
As far as we know, real specimens identifiable as
Hexinastrum
,
Hexalastromma
,
Pentalastromma
and
Pentinastrum
have never been so far illustrated. Here we simply put together these suspected genera. Six-armed genera might be conjoined specimens like in the Jurassic
Tritrabs worzeli
illustrated by
Dumitrica (2013b
: fig. 4.1). The oldest available
names
are
Hexinastrum
and
Pentinastrum
in
Haeckel (1882: 450
for
Hexinastrum
and 460 for
Pentinastrum
). If their morphology results from a conjoined phenomenon, six-armed specimens like
Hexinastrum
are predicted to be found rather than starlike five-armed specimens like
Pentinastrum
.
Tricranastrum
Tricranastrum
corresponds to the current usage of
Myelastrum
. The following genera have the same
type
species, respectively:
Myelastrum
,
Myelastrella
and
Spongomyelastrum
;
Dicranastrum
,
Dicranaster
and
Spongodicranastrum
;
Pentophiastromma
and
Spongopentophiastrum
. The ontogenetic changes at intraspecies or species level are well illustrated in
Tan & Tchang (1976: 246-250)
. The authors seemed to consider these variations at a genus level but their illustrated morphological variations are obviously continuous among specimens. The number of arms at least is variable at intraspecific level because if it is used as a genus criterion, many genera would be “created” by monotypy. The oldest available name is
Tricranastrum
Haeckel (1879: 705)
. As this name was once used as valid in
van de Paverd (1995: 175)
, it is unable to keep the name
Myelastrum
.
Tessarastrum
The difference between
Tessarastrum
and
Ommatocampe
is in the number of arms but two of the four arms of
Tessarastrum
are developed in secondary growth mode in the sense of
Ogane
et al.
(2010)
(the supporting image for
Tessarastrella
in the
Atlas
).
Hagiastromma
is characterized by a patagium and dissimilar longitudinal arms (
Campbell 1954
: D86) whereas
Tessarostromma
by a bilateral symmetry along the long axis, the presence of a patagium and dissimilar arms (
Campbell 1954
: D88 as
Tessarastromma
, the invalid name at present). The shorter arms illustrated in the
type
images of
Hagiastromma
and
Tessarostromma
are explained by a different ontogenetic growth in
Tessarastrum
. The patagium changes during ontogenetic growth in the
Euchitoniidae
. The bilateral symmetry change is related to intraspecies variation. All of these available genera were simultaneously published inHaeckel (1887: 543 for
Hagiastromma
; 547 for
Tessarastrum
and
Tessarastrella
; 548 for
Tessarostromma
). Of these,
Tessarastrum
is the only name established with a generic-rank.
Trigonastrum
This genus is different from
Dictyocoryne
due to the significant diversity of each arm. The illustrated
type
specimen of
Dictyastromma
shows a significant diversity but the probable same species of
Dictyastrum trispinosum
looks to be a
Dictyocoryne
(the supporting image for
Dictyastromma
in the
Atlas
). The stratigraphically important species “
Amphirhopalum ypsilon
” is classified into this genus, although this species itself is a
nomen dubium
due to an un-illustrated
type
.
Monaxonium
initially belong to the
Panartidae
(=
Zygartidae
originally) (
Popofsky 1912: 125-126
) and it was later moved to the
Spongodiscidae
sensu
Riedel (1971: 653)
. The distinguishing features of the listed genera are the occurrence of terminal spines (
Campbell 1954
: D86 for
Amphicraspedina
and
Dictyastromma
) or spinules on arms (
Campbell 1954
: D89 for
Rhopalastromma
), the occurrence of a patagium (
Amphicraspedina
,
Rhopalastromma
;
Campbell 1954
: D86 for
Chitonastromma
, D88 for
Trigonastromma
), the occurrence of two to three forked arms (
Amphicraspedina
,
Chitonastromma
,
Trigonastromma
) or undivided arms (
Dictyastromma
). As repeatedly responsible of the validity of genera in
Euchitoniidae
, terminal spines and spinules on arms as well as patagium are intraspecies variations. The condition of forked arms is so variable that it is considered as an intraspecies or species variation. All available synonym genera except for
Monaxonium
were simultaneously published in
Haeckel (1887: 523
for
Amphicraspedina
and
Amphirrhopoma
; 525 for
Dictyastromma
; 528 for
Rhopalastromma
; 537 for
Chitonastromma
; 538 for
Trigonastrum
; 539 for
Trigonastrella
,
Trigonastromma
). As the forked arms are one of the characters of this morphotype,
Trigonastrum
is selected as the valid name.