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341
ISSN 0031-0301, Paleontological Journal, 2019, Vol. 53, No. 4, pp. 341–345. © Pleiades Publishing, Ltd., 2019.
Russian Text © The Author(s), 2019, published in Paleontologicheskii Zhurnal, 2019, No. 4, pp. 20–24.
A New Genus Perakella gen. nov. (Gastropoda)
from the Lower Permian Reef Limestone of Shakh-Tau
A. V. Mazaev*
Borissiak Paleontological Institute, Russian Academy of Sciences, Moscow, 117647 Russia
*e-mail: mazaev.av@mail.ru
Received August 16, 2018; revised September 18, 2018; accepted December 28, 2018
Abstract—A new genus Perakella gen. nov. including two species: P. shakhtauensis sp. nov. from the Upper
Asselian of Middle Cisuralia and P. batteni sp. nov. from the Middle Permian of Malaysia, is described. A
unique find of this genus in the reef limestones of Shakhtau is further evidence of the presence of elements of
Tethyan taxa in the Early Permian communities of the Uralian corridor.
Keywords: Gastropoda, Phymatopleuridae, Borestus, Platypleurotomaria, Perakella, morphology, taxonomy,
Tethyan fauna, Ural corridor, Permian, Asselian Stage
DOI: 10.1134/S0031030119040087
INTRODUCTION
This paper provides the description a new genus,
Perakella gen. nov., which includes two species:
P. shakhtauensis sp. nov. and P. batteni sp. nov. The
former species was found in the reef limestone of
Shakh-Tau of South Cisuralia; the latter was errone-
ously identif ied by Batten (1972) as Borestus planiapi-
cata (Wanner, 19 42) from th e early Permian limestone
of Malaysia. The age of the latter, as indicated by Bat-
ten, is determined within very wide limits: Late Art-
inskian–Early Guadalupian.
The occurrence of Perakella in the reef limestone
of Shakh-Tau, following the recent account of speci-
mens of the ammonoid Properrinites sp. (Perrinitidae)
(Leonova and Boiko, 2018), supports the presence of
Tethyan taxa in the Lower Permian molluskan assem-
blages of the Uralian corridor. This presence indicates
a connection between the two large marine basins in
the Early Permian, and a similarity in their tempera-
tures and salinity.
The Uralian species is geochronologically older.
Apparently, by the time of the closure of the southern
termination of the Uralian corridor in the Late Art-
inskian, the genus Perakella had become widespread.
The rarity of occurrences of this genus can most likely
be explained by the poor state of knowledge of the tax-
onomic composition of Late Paleozoic gastropod
assemblages from various regions.
MATERIAL
Specimens of Perakella shakhtauensis described in
this paper were collected by the author in the Upper
Asselian Reef limestones of the Shakh-Tau Quarry
(South Cisuralia). The geographical location details of
the localities were previously published by Mazaev
(2019).
During five expeditions from 2015 to 2017, speci-
mens of this species were only found twice: in the
spring of 2016, five specimens were found in one small
block of limestone. (Locality no. 5538/7, south wall of
the Shakh-Tau open pit, elevations 145–150), and one
specimen was found in autumn 2016 at Locality
no. 5538/11 (south wall of the Shakh-Tau open pit,
elevations 135–140).
All specimens are represented by shell imprints in
limestone. Unfortunately, the surface of all imprints is
covered by thin crusts of calcite crystals. The mechan-
ical removal of these crusts under the binocular
microscope slightly improved the quality of the latex
casts obtained, but the host rock matrix was extremely
porous. For this reason, almost all casts only repro-
duce generalized details of the ornamentation.
The only specimen where fragments of the shell
surface have fine details of the sculpture preserved
comes from Locality no. 5538/11 (Figs. 1a–1f). To
improve the quality of photographs, the casts were
coated beforehand with butyral solution, and then
with ammonium chloride. This technique provided a
more accurate photography of elements of the sculp-
ture on the background of the imprint, taken from a
porous surface. In respect to other parameters, the
casts were quite informative, both in the transfer of the
general features of the shape of the shells, and
the details of the aperture.
The material is housed at the Orlov Paleontological
Museum, Paleontological Institute of the Russian
Academy of Sciences, coll. no. 5538.
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PALEONTOLOGICAL JOURNAL Vol. 53 No. 4 2019
MAZAEV
DISCUSSION
In a diverse assemblage of Middle Permian gastro-
pods from the vicinity of Perak (Malaysia), Batten
(Batten, 1972) described two gastropod specimens,
which he identified as Borestus planiapicata (Wanner,
1942). Platypleurotomaria planiapicata Wanner, 1942
was established by Wanner (1942) based on material
from Timor and proposed as the type species for the
monotypic genus Platypleurotomaria Wanner, 1942.
However, Knight et al. (1960), and later Batten
(Batten, 1972), based on the position of the seleni-
zone, assigned this species to the genus Borestus
Thomas, 1940, indicating Platypleurotomaria as its
junior synonym.
Fig. 1. Perakella shakhtauensis gen. et sp. nov., latex casts; all ×3, except (b) and (f): (a–f) holotype PIN, no. 5538/11-4: (a) lateral
view, (b) fragment of the lateral whorl surface, ×6, (c) apertural view, (d) top oblique view, (e) opposite to apertural view, (f) initial
whorls, ×20; (g, h) paratype PIN, no. 5538/7-170: (g) top oblique view, (h) apertural view; (i) paratype PIN, no. 5538/7-185,
lateral view; (j, k) paratype PIN, no. 5538/7-181: (j) lateral view, (k) apertural view; (l, m) paratype PIN, no. 5538/7-161: (l) lat-
eral view, (m) apertural view.
1 mm0
5 mm0
5 mm0
(a)
(b)
(c) (d) (e)
(f)
(g) (h)
(i)
(j)
(k)(l) (m)
PALEONTOLOGICAL JOURNAL Vol. 53 No. 4 2019
A NEW GENUS PERAKELLA GEN. NOV. (GASTROPODA) 343
Regardless of the systematic position of the species
described by Wanner from Timor, the obvious morpho-
logical differences between the Malaysian specimens
described by Batten (Batten, 1972, text-figs. 47, 48) and
the Timorese type materials of Wanner (Batten, 1972,
text-figs. 45, 46) cannot be considered to be species
variability, as suggested by Batten.
Despite Batten’s statements, referring to his earlier
studies (Batten, 1966, pp. 100–101), the initial whorls
of Timorese and Malaysian taxa differ significantly.
The level of differences observed appear to indicate
a differentiation higher than the species level. The
teleoconchs of these specimens also differ in rotational
profile, set of sculptural elements, their position, size
and the type of their selenizone. The study revealed
that the Malaysian specimens, identified by Batten as
Borestus planiapicata (Wanner, 1942), have features
similar to those of the Uralian species Perakella
shakhtauensis and obviously represent a separate spe-
cies, described here as Perakella batteni. A set of spe-
cific traits of these two species make up the diagnosis
of a new genus Perakella.
The type of whorl profile and the position of the
selenizone in the middle of the lateral surface are sim-
ilar in the new genus Perakella and in Borestus
Thomas, 1940, Dictyotomaria Knight, 1945, Glypto-
tomaria Knight, 1945, Phymatopleura Girty, 1939,
Callitomaria Batten, 1956, and also determine its sys-
tematic affiliation to the family Phymatopleuridae
Batten, 1956. At the same time, the type of selenizone
of this genus has little in common with both Borestus
and other genera of this family. The boundaries of the
selenizone are not defined by either the spiral elements
of the sculpture (despite their presence), or by the
presence of well-defined lunules. In fact, the seleni-
zone is indicated only by a change in the shape of the
growth lines.
Thus, the combination of the type of the selenizone
with the whorl profile and with the general propor-
tions of the shell (the ratio of the height of the last
whorl to the height of the coil) are defining characters
of Perakella, and provide an optimal diagnosis of the
new genus, which clearly separates it from other repre-
sentatives of Phymatopleuridae.
SYSTEMATIC PALEONTOLOGY
Family Phymatopleuridae Batten, 1956
Genus Perakella Mazaev, gen. nov.
E t y m o l o g y. From the Malaysian toponym
Perak, where the first species of this genus was found.
Type s p e c i e s. Perakella shakhtauensis gen. et
sp. nov.; Russia, Bashkortostan, Shakh-Tau; Lower
Permian, Asselian.
D i a g n o s i s. Shell turbiniform, subsutural ramp
bounded by a sharp keel; last whorl is encompassing,
comparable to height of coil. Initial whorls almost
high-spired, rounded in section; suture depressed.
Ornamentation of fine cordlike spiral ribs. Inter rib
spaces wide and flattened. Selenizone wide, shifted
downward from keel at a distance almost equal to its
width; not pronounced in profile, its position is
defined only by a change in the shape of the growth
lines; above and below delineated by spiral ribs, the
thickness of does not exceed the width of the other spi-
ral ribs. Similar spiral ribs, one or more in number, can
be present on the selenizone. Umbilicus absent. Colu-
mella long, straight, or weakly curved. Growth lines
distinct, fine; almost straight or weakly prosocyrte on
subsutural ramp, and below selenizone; they are pro-
socyrte above selenizone.
Species composition. Two species: Pera-
kella shakhtauensis sp. nov. from the Early Permian of
Eastern Europe and P. batteni sp. nov. from the Middle
Permian of Malaysia.
C o m p a r i s o n. This genus is distinguished from
Platypleurotomaria Wanner, 1942 and Borestus
Thomas, 1940 by the elongated initial whorls, absence
of clearly developed collabral ornamentation, and in
the fundamentally different morphology of the seleni-
zone, which in the new genus is distinguished only
when the growth lines are present.
Perakella shakhtauensis Mazaev, sp. nov.
E t y m o l o g y. From Shakh-Tau.
H o l o t y p e. PIN, no. 5538/11-4, shell imprint;
Bashkortostan, Shakh-Tau, locality no. 5538/11;
Lower Permian, Upper Asselian.
D e s c r i p t i o n (Fig. 1). The shell turbiniform, of
approximately seven whorls. The protoconch mor-
phology is not known. The first three–four initial
whorls are rounded in cross–section, ornamented by
thin spiral ribs. Beginning from approximately the
fourth whorl, the subsutural ramp is gradually formed,
separated in the last two whorls by a sharp keel. The
subsutural ramp is slightly narrower than the lateral
surface width. The subsutural ramp is slightly convex
in profile, ornamented by four spiral cordlike ribs. The
first two ribs are separated by a relatively narrow inter-
costal space; the width of a band between the suture
and the first rib equals the width of this intercostal
space. The third rib is more massive, separated from
the second by a slightly larger distance. The fourth rib
marks the keel, the intercostal space between it and the
third rib is the largest and equals the selenizone width.
All intercostal spaces are distinctly concave, and the
last, occurring near the keel, like the keel itself, has an
undulating surface. The lateral surface of the whorl is
straight or slightly convex in profile, subvertical or
slightly inclined, so that the whorl periphery point
marks the last lower or penultimate rib. There are nine
ribs altogether, the upper rib marks the keel (which is
in fact the fourth rib of the subsutural ramp). The two
upper and two lower ribs are slightly wider and have a
larger intercostal space, which is approximately the
344
PALEONTOLOGICAL JOURNAL Vol. 53 No. 4 2019
MAZAEV
same as the selenizone width. Other ribs (from third to
seventh) are f iner, separated by relatively narrow inter-
costal spaces. The selenizone is between the fourth
and sixth ribs. The fifth rib is approximately in the
middle of the selenizone. The ninth rib marks the
boundary between the lateral and basal surfaces of the
whorl. The lateral surface transits to the basal surfaces
relatively smoothly. The basal surface is relatively con-
vex, inclined to the shell axis approximately 45°. It is
ornamented by evenly wide cordlike spiral ribs (10 to
12 in number), separated by approximately equal, rel-
atively wide spaces. The uppermost space is somewhat
wider than the others. The aperture is of complex
shape. The columella is very long, arched, with a dis-
tinct narrow turnout of columellar lip. The transition
of the columellar lip to the basal is smooth. The
growth lines are distinct, thin; above and below the
keel, and also are almost cordlike on the selenizone.
On the subsutural ramp, owing to its poor preserva-
tion, growth lines are discernible only near the keel,
where they are straight and approaching it at the right
angle. On the lateral surface of the whorl, the growth
lines above the selenizone are straight, prosocline,
sharply bent immediately near the selenizone, forming
lunules on the selenizone, prosocyrte below the seleni-
zone and continuing smoothly onto the basal surface.
Dimensions in mm:
C o m p a r i s o n. This species is distinguished
from P. batteni by the later development of the keel and
by the narrower subsutural ramp with fewer spiral ribs
above it.
O c c u r r e n c e. Bashkortostan, Shakh-Tau reef;
Lower Permian, Asselian.
M a t e r i a l. Six specimens: locality no. 5538/75
specimens; locality no. 5538/11 specimen.
Perakella batteni Mazaev, sp. nov.
Borestus planiapicata (non Wanner, 1942): Batten, 1972, p. 37,
text-figs. 47, 48.
E t y m o l o g y. After the paleontologist R.L. Batten.
H o l o t y p e. American Museum of Natural His-
tory (AMNH), no. 29069; Malaysia, Perak, Kinta
Valley near Kampar; Lower–Middle Permian.
Description (Fig. 2). The shell is turbiniform,
of approximately seven whorls. The morphology of the
protoconch and first two initial whorls is not known.
Beginning approximately from the third whorl, a sharp
cordlike keel appears, which subdivides the whorl into
subsutural ramp and lateral surfaces. The subsutural
ramp is slightly narrower than the lateral surface of the
whorl. The subsutural ramp is convex in profile; in the
last whorl ornamented by six spiral cordlike ribs. The
sixth rib marks a sharp keel. The intercostal space near
the keel is somewhat wide than the other spaces,
smooth or with fine collabral ribs. The lateral surface
of the whorl is straight in profile, ornamented by eight
spiral cordlike ribs, including the rib marking the keel,
and also the rib marking the boundary with the basal
surface. The last two ribs are somewhat larger than the
other. The intercostals spaces are wide; the upper and
lower spaces are noticeably wider than the others. The
surface of the upper intercostal space possesses very
frequent cordlike collabral slightly opisthocline col-
labral ribs. The selenizone is between the third and
fifth ribs. The fourth rib is approximately in the middle
of the selenizone. The transition of the lateral surface
into the basal surface is relatively smooth. The basal
surface is convex, ornamented by cord like spiral ribs,
the width of which equals the thickness of the spiral
ribs of the lateral surface. The growth lines are distinct
and fine, almost straight on the subsutural ramp,
approach the keel at a right angle; on the lateral sur-
face, growth lines above and below the selenizone are
prosocyrte, forming distinct lunules on the selenizone.
Specimen no. Shell shape Maximum diameter
5538/11-4 holotype 14.3 11.5
5538/7-161 >19.9 16.7
Fig. 2. Perakella batteni gen. et sp. nov.; fossil shells, ×2
(after Batten, 1972, text-figs. 47, 48): (a) paratype AMNH
29068, oblique lateral view, (b) holotype AMNH 29069,
lateral view.
(a)
(b)
PALEONTOLOGICAL JOURNAL Vol. 53 No. 4 2019
A NEW GENUS PERAKELLA GEN. NOV. (GASTROPODA) 345
Dimensions in mm:
C o m p a r i s o n. This species is distinguished
from P. shakhtauensis by the earlier development of the
keel between the subsutural ramp and the lateral sur-
face of the whorl, and by the greater number of spiral
ribs on the subsutural ramp.
R e m a r k s. The size of the specimens and their
illustrations are from Batten (1972, text-figs. 47, 48).
The descriptions are based on these illustrations. Bat-
ten’s description for Borestus planiapicata, contain
characters both from Wanner’s original specimens
(Batten, 1972, text-figs. 45, 46), and Malaysian speci-
mens.
M a t e r i a l. Two specimens from the type locality.
ACKNOWLEDGMENTS
I am grateful to T.B. Leonova (Paleontological Institute,
Russian Academy of Sciences) for critically reading the
manuscript and valuable comments.
FUNDING
The study is supported by the AO Bashkirian Soda
Company, in the framework of the research contract
“Monographic study of the Early Permian fossils of Shakh-
Tau (gastropods).”
REFERENCES
Batten, R.L., The lower Carboniferous gastropod fauna
from the Hotwells Limestone of Compton Martin, Somer-
set [Parts 1–2], Palaeontogr. Soc. Monogr., 1966, vol. 120,
no. (1965), pp. 53–109.
Batten, R.L., Permian gastropods and chitons from Perak,
Malaysia. Part I. Chitons, bellerophontids, euomphalids
and pleurotomarians, Bull. Am. Mus. Nat. Hist., 1972,
vol. 147, pp. 1–44.
Knight, J.B., Cox, L.R., Keen, A.M., Batten, R.L., Yochel-
son, E.L., and Robertson, R., Systematic descriptions,
Treatise on Invertebrate Paleontology. Part I. Mollusca. Law-
rence: Geol. Soc. Am.; Univ. Kansas Press, 1960, pp. 169–
324.
Leonova, T.B. and Boiko, M.S., A unique find of perrinit-
ids (Ammonoidea) in the Early Permian Shakh-Tau reef
(Bashkortostan), in Proc. of Kazan Golovkinsky Strati-
graphic Meeting, 2017. Advances in Devonian, Carboniferous,
and Permian Research: Stratigraphy, Environments, Climate
and Resources, Nurgaliev, D., Ed., Bologna: Fillodiritto,
2018, pp. 163–166.
Mazaev, A.V., A New Species of the Genus Bellazona (Gas-
tropoda) from Lower Permian Reef Limestones of Mt.
Shakhtau (Southern Cis-Urals), Paleontol. J ., 2019, vol. 53,
no. 3, pp. 252–256.
Wanner, C., Neue Beiträge zur Gastropoden–Fauna des
Perm von Timor, in Geological Expedition of the University of
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the Netherlands East Indies. Amsterdam: N.V. Noord-Hol-
landsche Uitgevers Maatschappij, 1942, vol. 4, pp. 133–
228.
Translated by S. Nikolaeva
Specimen no. Shell height Maximum diameter
AMNH 29068 paratype 24.1 12.1
AMNH 29069 holotype 19.8 14.5