Agastograptus, a synonym of Plectograptus (Retiolitidae, Graptolithina)
Author
Kozłowska-Dawidziuk, Anna
text
Acta Palaeontologica Polonica
2002
2002-12-31
47
3
459
467
journal article
300550
10.5281/zenodo.13173828
3dbd2041-0711-4651-bdf5-2d771a498f0c
1732-2421
13173828
Spinograptus munchi
(
Eisenack, 1951
)
Fig. 3A, H
.
Retiolites munchi
n. sp.
;
Eisenack1951: 136
, pl. 22: 9–12, pl. 23: 3–5, pl. 24: 1.
Agastograptus munchi
(Eisenack)
;
Obut and Zaslavskaya 1983: 111– 112
, pl. 22: 4, pl. 26: 1–4.
Spinograptus munchi
(Eisenack)
;
Kozłowska−Dawidziuk 1995: 316– 317
, figs. 31A, 32A, B.
non
Agastograptus munchi
(Eisenack)
; Richards, Packham, Wright and Williamson 1995: 32, figs. 18E–H, 19D–H.
Diagnosis
.—See
Kozłowska−Dawidziuk 1995
.
Description
.—The longest specimen of
10 mm
, with robust lists, represents mature rhabdosome with 10 pairs of thecae. Ancora umbrella is about
1 mm
wide, composed of lists thinner than in the rest of the rhabdosome. Maximum width of lateral walls (between pleural lists) is 1.6 mm at the level of 5
th
pair of thecae, and is the same to end of the rhabdosome. Paired apertural processes well developed of typical shape for the species. Two first pairs of thecae possess smaller and thinner processes, the strongest are in the middle part of rhabdosome. In the distal part they are not present, probably broken off. The rest of specimens represent fragments of mature and younger (thinner lists) stages. Virgella is preserved in young rhabdosomes.
Discussion
.—The new material represents the rhabdosome features as in the
type
material (
Eisenack 1951
) as well as the material described from Všeradice,
Czech Republic
(
Kozłowska−Dawidziuk et al. 2001
).
S. munchi
differs from other species of
Spinograptus
in lacking an ancora sleeve reticulum and mid−ventral lists (see
Kozłowska−Dawidziuk 1995
,
1997
). It possesses distinctive, paired bifurcated reticulofusellar apertural processes, (
Fig. 3A, H
). Material described by
Rickards et al. (1995)
may represent some
Spinograptus
species
, similar to
S. latespinosus
, with a developed reticulum. The difference between
S. munchi
and
S. latespinosus
is in the lack of reticulum of ancora sleeve and ventral walls, different shape of apertural processes as well as absence of a mid−ventral list and appendix in
S. munchi
.
Material
.—The new material consists of dozens of fragments and 9 more complete rhabdosomes, and comes from
Poland
, Bartoszyce borehole depths: 1626.6 m, 1627.0 m, 1634.5 m, 1635.5 m, 1641.0 m.
Occurrence
.—
Spinograptus munchi
probably occurs in the
Colonograptus ludensis
Biozone
(uppermost upper Homerian) from unknown locality of erratic boulders of the Eisenack material (personal examination by the present author 1998), the
Gothograptus nassa
Biozone
from
Kaliningrad
,
Russia
(
Obut and Zaslavskaya 1983
), the lower part of the
Neodiversograptus nilssoni
Biozone (
Kozłowska−Dawidziuk 1995
)
and
Colonograptus praedeubeli
and
C. deubeli
biozones of
Poland
, and in the middle part of
C. praedeubeli
–
C. deubeli
Biozone
of Všeradice, Barrandian,
Czech Republic
(
Kozłowska−Dawidziuk et al. 2001
).