Vetlugospermum and Vetlugospermaceae: A new genus and family of peltasperms from the Lower Triassic of Moscow syneclise (Russia)

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Original article

Vetlugospermum

and

Vetlugospermaceae:

A

new

genus

and

family

of

peltaspermsfrom

the

Lower

Triassic of

Moscow

syneclise

(Russia)§

Serge V. Naugolnykh

Laboratory

of

Paleofloristics,

Geological

Institute,

Russian

Academy

of

Sciences,

Pyzhevsky

per.

7,

119017

Moscow,

Russia

1.

Introduction

The time just before and after the Permian/Triassic ecosystem

crises (the so-called ‘‘time vicinity’’ of P/T boundary), also known

by the mass extinction of animals and plants (Retallack, 1995; Gall

et al., 1998), was characterized by the appearance of short-lived

genera. This phenomenon was first established on the basis of

invertebrate and tetrapod data (Kalandadze and Rautian, 1993),

but was later also recorded by palaeobotanists (Naugolnykh, 2005,

2007b; Mogutcheva and Naugolnykh, 2010). Such short-lived

plant genera were described from the uppermost Permian deposits

of the Vladimirian stage (uppermost Permian of Russia: Naugol-

nykh, 2005, 2006) from the European part of Russia (for example,

Vjaznikopteris Naugolnykh, 2006), and from the lowermost Triassic

deposits (Induan stage) of the Tunguska basin, Siberia (e.g.,

Mesocrossotheca Naugolnykh and Mogutcheva in Mogutcheva and

Naugolnykh, 2001; Gagariostrobus Mogutcheva in Mogutcheva and

Grigorieva, 1987, emend. Mogutcheva and Naugolnykh, 2010). One

of these short-lived genera, the new genus Vetlugospermum

Naugolnykh, is described herein from lowermost Triassic deposits

of the European part of Russia.

This new genus belongs to the peltasperms, a group of

gymnosperms now considered as a class by many botanists

(e.g., Rojas, 1925; Cronquist, 1981; Doweld, 2001). A broad concept

of peltasperms (the order Peltaspermales) was proposed by Meyen

(1982,

1983,

1984,

1987,

1988). Meyen’s

concept

of

the

orderPeltaspermales included the following families: Trichopityaceae,

Peltaspermaceae, Umkomasiaceae (= Corystospermaceae), Cardi-

olepidaceae (now Angaropeltaceae, = Angaropeltidaceae nom.

ungramm.; see discussion below). Thus, the order Peltaspermales

according to Meyen included not only gymnosperms with classical

(typical) ovuliferous discs and their morphogenetic derivates, but

also gymnosperms with foliar and cladoid seed-bearing organs of

different types. Within such an extremely broad understanding of

the Peltaspermales, Meyen included the primitive Palaeozoic

ginkgophytes, which the author considers to belong to another line

of gymnosperm evolution (Naugolnykh, 2007a).

After following Meyen’s concept of the order Peltaspermales for

a long time (e.g., Naugolnykh, 1998), and after a detailed analysis of

the systematics of early ginkgophytes, it proved necessary to

modify Meyen’s concept and exclude the families Trichopityaceae

and Umkomasiaceae from the order. The Trichopityaceae together

with the closely related families Psygmophyllaceae and Cheir-

ocladaceae are placed in the order Ginkgoales (Naugolnykh,

2007a).

According to the current author’s viewpoint, only three families

(Peltaspermaceae, Vetlugospermaceae, and Angaropeltaceae) can

be assigned to the Peltaspermales. The genera attributed to these

families are briefly discussed below.

2. Regional stratigraphy

Regional stratigraphy of the uppermost Permian and lowermost

Triassic deposits in the European part of Russia has been under

Geobios

45

(2012)

451–462

A

R

T

I

C

L

E

I

N

F

O

Article history:

Received 14 April 2011

Accepted 28 October 2011

Available online 14 July 2012

Keywords:

Peltasperms

Gymnosperms

Systematics

New taxa

Permian

Triassic

P/T boundary

A

B

S

T

R

A

C

T

A new genusand species,Vetlugospermumrombicum, belonging to thepeltaspermalean gymnosperms is

described. Vetlugospermum nov. gen. andNavipelta are placed into the new family Vetlugospermaceae.

General problems of peltasperm systematics and relationships between the different genera from the

Permian and Triassic are discussed.

2012

Published by Elsevier Masson SAS.

§ Corresponding editor: Marc Philippe.

E-mail address: [email protected]

Available

online

at

www.sciencedirect.com

0016-6995/$ – see front matter

2012 Published by Elsevier Masson SAS.

http://dx.doi.org/10.1016/j.geobios.2011.10.009




serious discussion for the last few decades. Traditionally it was

thought that there was a gap between the uppermost Permian

(Tatarian) and the lowermost Triassic deposits in that area. But a

careful study of several representative sections located in the

Vologda (Nedubrovo section), Vladimir (Vjazniki section), Nizhni

Novgorod regions (Gorohovets section), and the Vetluga River

basin

(Spasskoe

locality)

has

shown

stratigraphical

continuity

inseveral places in the European part of Russia (Lozovsky and

Esaulova, 1998). The deposits between the upper part of the

Vjatskian stage (formerly upper part of the Tatarian stage) and the

lower part of the Vetluga Series (Vokhminian Formation corre-

sponding to the Induan stage of the International Stratigraphic

Scale) were singled out for a new stage of the uppermost Permian

of the Russian platform. This stage, established by the author

(Naugolnykh, 2005), was named as the Vladimirian stage with a

stratotype section located near the City of Vjazniki. This stage was

accepted and used in several recently published stratigraphic,

palaeontological and geological works (Ozhgibesov et al., 2009;

Pukhonto and Naugolnykh, 2009; Yang et al., 2011). It was cited by

other stratigraphers dealing with the Upper Permian and Lower

Triassic deposits in that area (Lozovsky and Kukhtinov, 2007),

although in the latter work another name (Vjaznikovskian, a later

synonym of Vladimirian) was used for this stratigraphic interval.

The name ‘‘Vjaznikovskian’’ was preoccupied and in use before the

proposal by Lozovsky and Kukhtinov (Strock et al., 1984) and so

cannot be used in any other different stratigraphic sense from its

original meaning. The Vladimirian stage can be correlated with the

Zechstein deposits in Western Europe and synchronous deposits in

Northern China on the basis of common plant macrofossils

(Lepidopteris martinsii and its nearest relatives, Ullmannia, and

Neocalamites mansfeldicus). The Vladimirian stage is more or less

comparable to the Wuchiapingian stage of the International

Stratigraphic Scale.

The deposits of the Spasskoe locality are slightly younger than

the Vladimirian stage and should be regarded as the lowermost

Triassic based on Tupilakosaurus and Lystrosaurus (Ivakhnenko

et al., 1997). However, the lower part of the Spasskoe section may

be of Late Permian age, because a Daptocephalus-like dicynodont

skull was found nearby in the village Voskresenskoe (Petukhov,

1992; Lucas, 2005).

The Nedubrovo section, containing remains of Navipelta

Karasev, is regarded by the author as Vladimirian in age, but

the Spasskoe locality containing Vetlugospermum nov. gen.

remains is

slightly younger; therefore

Navipelta

and Vetlugosper-

mum nov. gen. were probably separated by at least several

thousand years.

3.

Material,

source

strata,

and

methods

All the material described in this paper comes from theSpasskoe locality situated in the middle part of the Vetluga River

Basin, on the left (east) bank of the river near Spasskoe village

(Fig. 1). This collection was kindly provided to the author by

geologists Arefiev, Brodjazhenko, and Petukhov (all from Moscow).

The Spasskoe locality is very well known as an important source of

numerous Lower Triassic vertebrate fossils: Tupilakosauridae:

Tupilakosaurus wetlugensis Shishkin; Bystrowianidae: Axitectum

vjushkovi Shishkin and Novikov; Procolophonidae: Phaanthosaurus

ignatievii Tchudinov and Vjushkov; Proterosuchidae: Vonhuenia

friedrichi Sennikov; Prolacertidae: Microcnemis sp. (Ivakhnenko

et al., 1997). The strata of the Vokhminian Series exposed in the

Spasskoe locality also contain numerous ostracods (Strock et al.,

1984): Darwinula fragilis Schn., D. oblonga Schn., D. triassica Belous.,

D. mera Misch., D. cara Misch., D. indemnis Misch., Gerdalia longaBelous., G. polenovi Belous., G. rixosa Misch., G. variabilis Misch.,

G. compressa Misch.

The presence of fossil plant debris in the deposits of the

Spasskoe locality and adjacent areas was noted by many

stratigraphers and paleontologists (Strock et al., 1984), but no

details were published untilnow. The plant fossils were collected

from a lens of blue-gray or sometimes slightly yellowish

aleurolites and siltstones with fine sandy intercalations and thin

clayey laminations.The plant fossil-bearing layer is located in the

upper part of the lens. There are small clay or argillite pebbles at

the very basalpart of the layer (Figs. 2 and3(2,3)).The lithology of

the fossil-bearing deposit points to a gradational pattern

indicating high energy stream conditions (pebble-containing

basal conglomerate), through middle energy conditions (middle

sandy part), to very slow or even stable stagnate conditions of a

shallow lake

in

the uppermost

clayey part

of

the sequence. The

plant fossils are concentrated in the middle (sandy) part of the

layer.

The maximal thickness of the fossil-bearing layer (the middle

sandy part of the lense) is 10 cm and gradually decreases in a

lateral direction. The observed lateral extension of the layer is 60 to

70 cm. The upper surface of the layer is more or less smooth andhorizontal. The lower surface of the layer is wide U-shaped. The

lens, containing the fossil-bearing layer, lies in a monotonous

packet of red clays.

Most of the upper part of the Spasskoe sequence contains

numerous vertebrate fossils (separate vertebrae and other

postcranial elements, as well as rare skull fragments) of the

amphibian Tupilakosaurus wetlugensis (Ivakhnenko et al., 1997),

which clearly indicates the Early Triassic age of the upper part of

this outcrop. The taphonomy of the Spasskoe locality was briefly

discussed in a preliminary report by Petukhov (1992), who mainly

concentrated on the tetrapod remains.

According to the author, the deposits of the Spasskoe locality

represent sediments of a so-called ‘‘peneplain proluvium’’

(Tverdokhlebov, 1989), formed on a wide plain with occasionalrare shallow-water lakes and ephemeral streams that filled with

water only during infrequent and short wet seasons. The lens

Fig. 1. Geographical position of the Spasskoe locality (indicated by an asterisk).

S.V. Naugolnykh / Geobios 45 (2012) 451–462452




containing the plant fossils was deposited in the channels of such

an ephemeral short-lived stream during a wet season. The plant

remains studied have an uncommon type of preservation. Plant

tissues have been completely replaced by clay minerals and no

organic material is preserved. They are preserved in 3D, without

any secondary compression, and their 3D macromorphology can

be studied in great detail. Besides the 3D plant fossils, severalimpressions both of adaxial and abaxial surfaces occur.

For a better understanding of the plant morphology, the

author used a methodology initially adapted for the taphonom-

ic/morphodynamic analysis and reconstruction of the enigmatic

Late Proterozoic (Vendian) genus Inaria (Grazhdankin, 2000).

This method was applied to the present material with some

modifications, including the use of the photographs with

different magnifications and different light for adequate show-

ing of the original specimen topology and morphology. Only the

five best preserved fossils were selected for a detailed

description. The other available specimens were used as

additional material to support conclusions through the follow-

ing process (Figs. 3–7):

each selected specimen was figured as a hand-made line-

drawing traced from a high resolution photograph;

an analytical reconstruction of the position of the plant remain in

the sediment is shown, as well as a demonstration of how the

specimen is oriented towards to an observer. The actual

specimen is shown in black colour;

3D graphic block-diagrams were made for the most important

specimens;

the resulting conclusions were used for the reconstruction of thewhole reproductive unit.

4.

Systematic

paleontology

Class PELTASPERMOPSIDA Cronquist, 1981

Order PELTASPERMALES Taylor, 1981

Family VETLUGOSPERMACEAE nov. fam. Naugolnykh Type-genus: Vetlugospermum nov. gen. Naugolnykh

Distribution: Uppermost Permian and Lower Triassic of the

Russian platform.

Composition: Vetlugospermum nov. gen. Naugolnykh; Navi-

pelta Karasev, 2009.

Diagnosis: Female reproductive organs consisting of peltate

bilaterally symmetrical megasporophylls. Stalk attached to centerof adaxial surface of megasporophyll. Seeds round to ovoid,

platyspermic.

Fig. 2. Lithology of the plant-bearing layer of the Spasskoe locality (right) and its position (locality indicated by the trifoliar mark) in the general succession of the Lower

Triassic sediments in the Vetluga River Basin (left; modified after Lozovsky and Blom, 1998). Legend: 1: small clayey pebbles; 2: sand; 3: siltstone (argillite); 4: clay; 5: sandy

lenses in siltstones or in clay deposits; 6: level with plant macrofossils. Scale: 1 m (left) and 1 cm (right).

S.V. Naugolnykh / Geobios 45 (2012) 451–462 453




Remarks: This new family differs from the closely related

Peltaspermaceae in bilateral symmetry of seed-bearing shields(megasporophylls) with the stalk attached to the center of the

adaxial surface of the shield.

Genus

Vetlugospermum nov. gen. Naugolnykh

Type-species: Vetlugospermum rombicum nov. gen., nov. sp.

Naugolnykh

Composition: Type-species only.

Distribution: Uppermost Upper Permian (Vladimirian stage;

Naugolnykh, 2005) and lowermost Lower Triassic (Induan stage;

basal part of local Vetluga Series) of the Russian platform.

Diagnosis: Bilaterally symmetrical megasporophylls bearing

seeds around a central stalk. Adaxial surface of megasporophyll

shield has concentric ridge. Ridge consists of two symmetrical

branches

connected

to

each

other

in

upper

and

lower

margins

of megasporophyll shield. Ridge separated from megasporophyll

margin by horizontal limb.

Remarks: The most similar genus is Navipelta Karasev, 2009.

The new genus Vetlugospermum differs from Navipelta in:

presence of a distinctive adaxial protective ridge;

presence of a smaller number of seed scars (or seeds attached to

the megasporophyll [megasporangiate] shield);

negative relief (shallow depression) of the megasporophyll

abaxial surface;

different shape of the megasporophyll shield (the megasporo-

phyll of Navipelta is considerably wider, with the widest part

being at the pointed upper part; the megasporophyll of

Vetlugospermum nov. gen. is narrower, with the widest part at

the lower rounded part).

Moreover, Navipelta has no basal commissure, which is always

present and well-developed on the Vetlugospermum nov. gen.

megasporophyll shield. Besides, it is suggested that the cone-likeaggregations of Vetlugospermum nov. gen. consist of megaspor-

ophylls arranged in parastichi. In other words, the megaspor-

Fig. 3. Vetlugospermum rombicum nov. gen., nov. sp. (1, 4, 5) and lithology of the Spasskoe locality (2, 3). 1, spec. 4851/162a; 2, 3, 4851/162; 4, spec. 4851/162a-b; 5, spec.

4851/164. Scale bars: 1 cm.





ophylls sit closely spaced on the fertile axis in a diagonal

arrangement.

In

contrast

to

this,

Navipelta

had

megasporophyll

aggregations with the megasporophylls arranged in orthostichi,

forming vertical rows on the fertile axis. Nonetheless, both genera

are very similar and phylogenetically were undoubtedly close to

each other (see the ‘‘Discussion’’ section below). They are united

here into the new family Vetlugospermaceae.

Vetlugospermum nov. gen. differs from other peltaspermousfemale reproductive organs: Peltaspermum Harris (including

Peltaspermopsis Gomankov, younger synonym of Peltaspermum;

Naugolnykh, 2001, 2008), Aspidion Zalessky, Lopadiangium Zhao,

and Shenzhouspermum Yang, Xie and Wu in having bilateral

symmetry; from Autunia Krasser emend. Kerp in having numerous

seed scars ( Autunia has only two seed scars), and from Autuniopsis

Poort and Kerp (and also Autunia) in having central (not lateral or

marginal) stalk. A comparative analysis of the peltasperm genera

listed above is given under the ‘‘Discussion’’ section.

Vetlugospermum rombicum nov. gen., nov. sp. Naugolnykh

Figs. 3–8, 9(D,D1).

Holotype: GIN 4851/163d (Figs. 4(B), 6(4)).

Material examined:

Megasporophyll

shields

GIN

4851/162a-c(three well preserved specimens on one slab; six additional partly

preserved specimens on the same slab), 4851/163a-g (eight well

preserved specimens; d, holotype; five additional partly preserved

specimens

on

the

same

slab;

counterpart

of

4851/162),

4851/164,

4851/165, isolated seeds GIN 4851/162, 4851/163.

Diagnosis: Bilaterally symmetrical megasporophylls, bearing

10 to 12 seed scars around a central stalk. Seeds round to ovoid,

slightly flattened, platyspermic, longitudinally ribbed, with

narrow flat marginal limb formed by soft sarcotestal tissues.

Abaxial surface of megasporophyll shield has wide shallowcentral depression. Adaxial surface of megasporophyll shield has

well-developed ridge concentrically surrounding area where

seed scars are located. Ridge consists of two symmetrical

branches connected to each other in upper and lower margins

of megasporophyll shield. Ridge separated from megasporophyll

margin by wide horizontal limb oriented to ridge by right

angle.Description: The separate descriptions of the five best

preserved specimens are proposed. The specimen selected as

the holotype shows all the most important features characteristic

of both this genus and species.

The description includes information about functionally upper

outer (abaxial) and functionally lower inner (adaxial) surfaces of

megasporophyll, normally are seen on different specimens.The typical example of the outer (abaxial) surface of the

Vetlugospermum rombicum nov. gen., nov. sp. megasporophyll is

Fig. 4. Vetlugospermum rombicum nov. gen., nov. sp., Spasskoe locality. A. Spec. 4851/162a. B. Holotype 4851/163d. C. Spec. 4851/164. D. Spec. 4851/165. Scale bars: 1 cm.





shown on spec. GIN4851/162a (Fig. 4(A)). The megasporophyll is

12 mm long and 7 mm wide, of rhombic outline with a slightly

acute apical (upper) part. The outer surface has a clear but shallow

depression, expressed on the negative imprint as a raised area. Thedepression corresponds to the place of the adaxial (functionally

lower) surface where the stalk was attached to the megasporophyll

shield. The shield has a distinct marginal limb 3 to 4 mm wide,

occupying the space between the protective ridge (see below) and

megasporophyll margin. The adaxial surface of the megasporo-

phyll shield is smooth, with very weak unclear radial ribs and

furrows corresponding to the cellular structure of the megasporo-

phyll epidermis.

The holotype (GIN4851/163d; Figs. 4(B), 6(4)) shows a slightly

deeper layer of preserved mesophyll tissues. The general shape of

the holotype megasporophyll shield is rhombic. The shield is

10 mm long and 6 mm wide. Bilateral symmetry of the megaspo-

rophyll shield is clearly seen. The stalk is connected to the central

part of the megasporophyll shield and is flattened along themegasporophyll axis. There are small (0.8 mm in diameter) round

structures around the stalk (eight on the left side and five partly

preserved structures on the right side of the megasporophyll as it is

oriented on Fig. 4(B)). These round structures should reflect the

position of mechanical tissues surrounding seed scars, but the seed

scars themselves are not exposed on the holotype. There is a well-developed protective ridge disposed between the megasporophyll

margin and the location of the seed scar. This ridge on the holotype

is preserved as a long and deep split around the stalk and

submerged into rock matrix. The ridge is 0.2 mm thick. The ridge

comes along the megasporophyll margin, but is separated from it

by the marginal limb.

The third specimen (GIN 4851/164) shows an even deeper layer

of preserved mesophyll tissues (Fig. 4(C)). The megasporophyll

shield measures 9 14 mm. This specimen allows us to study a

partly exposed adaxial surface of this reproductive organ. The right

(according to position on Fig. 4(C)) marginal limb is fully detached.

Therefore one can observe a complete megasporophyll right ridge.

The left branch of the ridge is submerged into rock matrix and

exposed just as a split because of partly destroyed plant tissues.The place where the central stalk was attached to the megasporo-

phyll shield is noticeable. One side of the megasporophyll shield

Fig. 5. Vetlugospermum rombicum nov. gen., nov. sp., Spasskoe locality. 1, spec. 4851/163a; 2, spec. 4851/163a-b; 3, spec. 4851/163a; 4, spec. 4851/165; 5, spec. 4851/163c; 6,

spec. 4851/165; 7, spec. 4851/164. Scale bars: 1 cm.





also shows six round to ovoid seed scars. Each seed scar is

surrounded by a ring-like raised area (on the imprint of adaxial

surface this raised area looks like a small concentric depression).According to the author’s interpretation, these raised areas

correspond to borders of seed bases. The central scar diameter

is 0.4 mm, and the diameter of the seed scar together with the ring-

like uplifting is about 1.0 to 1.2 mm.

The fourth specimen (GIN4851/165) is an impression of the

adaxial surface of the megasporophyll shield. This specimen has

perfectly preserved seed scars. The left side (according to its

orientation of Fig. 4(D)) bears six seed scars and the right bears five.

As for the previous specimen, each scar is surrounded by ring-like

raised area, which appears as a small shallow depression on the

imprint. The marginal limb of this specimen is completely

detached. The specimen is about 5 9 mm, but the total size of

the megasporophyll shield could be larger (up to 14–15 mm long

and 8–9 mm wide).The fifth specimen (GIN4851/162c; Fig. 7) is preserved in

almost the same manner as the first one and represents an imprint

of the abaxial surface of the megasporophyll shield. Several

additional specimens allow study of the diversity of the same

morphological features, which can be observed on the fivespecimens described above.

The data summarized above are the basis for the reconstruction

of the Vetlugospermum rombicum nov. gen., nov. sp. megasporo-

phyll (Fig. 7, upper part).

5.

Systematics

of

peltasperms

Recently two main and substantially different taxonomical

approaches were used in peltasperm systematics.

The first approach is based on the traditional description of

different organs (leaves, male and female reproductive organs,

seeds, wood) separately under different names, even if the

probability of these organs belonging to the same parent plant

is very high. A good example of this approach is the excellentdescription of Lepidopteris callipteroides (Carpentier) Retallack

(Retallack, 2002) from the Lower Triassic of Australia and the

Fig. 6. Vetlugospermum rombicum nov. gen., nov. sp., Spasskoe locality. 1, spec. 4851/163e; 2, spec. 4851/163a-d-e; 3, spec. 4851/163f-g; 4, holotype 4851/163d; 5, spec. 4851/

163e; 6, spec. 4851/163 h. Scale bars: 1 cm.





associated reproductive organs: racemose aggregations of seed-

bearing discs, described as Peltaspermum townrovii Retallack, and

polliniferous organs, described as Permotheca helbyi Retallack.

Though all of these organs very likely belonged to one and the same

natural species, they were attributed to different ‘‘morpho-

genera’’: Lepidopteris, Peltaspermum, and Permotheca (Retallack,

2002).

Another example of usage of this approach is the monograph,

published by Schweitzer and Kirchner (1998), focused on Middle

and

Upper

Triassic

gymnosperms,

which

included

peltasperms

from Iran and Afghanistan, namely, Lepidopteris ottonis (Goeppert)

Schimper, Scytophyllum persicum (Schenk) Kilpper, and Peltasper-

mum decipiens Schweitzer and Kirchner. This approach to

peltasperm taxonomy and systematics conditionally can be called

‘‘segregative’’, because it segregates different organs of the same

parent plant into two or more different ‘‘morpho-genera’’. Thisapproach is very helpful in fieldwork, where the correlation of

isolated organs is not always clear. It allows us to avoid any

confusion with the taxonomic attribution of the plant fossils or

misinterpretation of parent plant.

The second approach, which can be called as an ‘‘uniting’’ or

‘‘agglomerative’’ approach because it unites morpho-taxa estab-

lished on different organs of presumably the same parent plant.

This agglomerative approach is well adapted for biological and

palaeoecological purposes, as it considers the fossil plant as a

biological unit on the whole-plant-concept (e.g., Kerp, 1988). The

main practical difficulty of agglomerative taxonomical approach is

selecting a proper name for the reconstructed whole plant. Some

palaeobotanists prefer to use the name proposed for female

reproductive organs (e.g., Peltaspermum, Autunia; Retallack andDilcher, 1988; Kerp, 1988; Poort and Kerp, 1990), even though

these names do not have priority to others (but see Bateman and

Hilton, 2009). Some palaeobotanists prefer to use the name that

have priority, whether or not it was proposed for reproductive

organs, e.g., for the peltasperm species Pursongia amalitzkii

Zalessky (Naugolnykh, 2001). Sometimes palaeobotanists use

both approaches as a combined taxonomy for discussion of

possible links between different taxa, their organs and interpreta-

tions;

for

example,

in

the

context

of

taxonomy

of

Autunia

Krasserand Arnhardtia sheibei (Gothan) Haubold and Kerp (Barthel, 2001).

Both approaches can be used successfully, but for different

purposes (Naugolnykh, 2001). The ‘‘segregative’’ approach can be

applied for preliminary determination of the plant fossils in field

work or in cases when we deal with fragmentarily preserved

material; it allows us to avoid any confusion in the reconstruction

of the parent plant, because similar organs could belong to

different species or even genera. The ‘‘agglomerative’’ approach

can be very useful for biological purposes, creating whole-plant-

concept taxa and using them in broad phylogenetic, palaeobiogeo-

graphic and palaeoecological applications.

Morphological characters and the current inclusion of peltas-

perm genera in three families (Peltaspermaceae, Vetlugosperma-

ceae, and Angaropeltaceae) are discussed below.

PELTASPERMACEAE Thomas, 1933

Peltaspermum Harris, 1937. This genus includes separate

(isolated) seed-bearing discs or ovulifores (= peltoids, megaspor-

angiate discs) with the seeds adaxially attached to the disc radially

and concentrically around a central stalk. The stalk is attached to

the central part of adaxial surface of the disc. The genus also

includes racemose or head-like aggregations of the seed-bearing

discs. Size of the discs normally does not exceed one-two

centimeters (the biggest specimens have discs of 2.5 cm in

diameter (Naugolnykh and Kerp, 1996). The discs can be flattened

or may have margins curved downwards (Retallack, 2002), but the

curved

margins

never

reach

the

disc

stalk.

The

functionally

upper

(abaxial) surface of the disc commonly has a small shallow

depression corresponding to where the stalk attached, but thisfeature varies within a species and some discs may lack a central

depression, or have only a small central raised area (e.g., Poort and

Kerp, 1990: pl. VI, fig. 5). There are three species of Peltaspermum

with a well-developed central raised area (‘‘apical cap’’):

P. turbanatum Anderson and Anderson, P. tridiscum Anderson

and Anderson, and P. quindiscum Anderson and Anderson, 2003).

A younger synonym of the genus name Peltaspermum is the

genus Peltaspermopsis Gomankov in Gomankov and Meyen, 1986.

The type-species of the genus Peltaspermopsis, P. buevichae

(Gomankov and Meyen) Gomankov, was originally attributed to

the genus Peltaspermum (Gomankov and Meyen, 1979). The other

species, Peltaspermopsis polyspermis Naug., has been transferred to

Peltaspermum (Naugolnykh, 2009). Sometimes the genus Peltas-

permum is used in a broad sense as a natural-genus (Poort andKerp, 1990) and such a concept includes both reproductive and

vegetative organs.

Aspidion Zalessky, 1937. This peltate reproductive organ was

attributed by M.D. Zalessky to plants Incertae sedis. The original

description was published in French (Zalessky, 1937: p. 80):

« Scutelle ovale arrondie atteignant un [diame tre] de 7 a 7,25 mm a

bords noduleux formant de larges festons (dents arrondies) faiblement

saillants, dans chacun desquels aboutit une fine nervure arque e. Ces

nervures se de tachent radialement au nombre de dix du point central

de la scutelle, ou elles s’unissent en un tronc commun se trouvant dans

un enfoncement ponctiforme de la scutelle. Sur l’empreinte ces

nervures ont l’air de costules; sur la scutelle me me, qui s’est conserve e

sous forme d’une pellicule charbonneuse, elles ont l’air de fines

cannelures».

Zalessky

suggested

that

Aspidion

is

a

leafy

part

of pteridosperm reproductive organ, but assumed it was male and not

female (Zalessky, 1937: p. 80): « Il est possible d’admettre que cette

Fig. 7. Vetlugospermum rombicum nov. gen., nov. sp., Spasskoe locality.

Reconstruction of the megasporophyll shield spec. 4851/162c: abaxial surface

and cross section (left), adaxial surface with seed scars and side view with shown

adaxial protective ridge (right), and scheme of abaxial surface imprint (below).

Scale bar: 1 cm.





scutelle pre sente une formation foliace e de quelque Pte ridosperme

dont sur le co te infe rieur e taient dispose s les organes reproducteurs

masculins (anthe res) ». According to the author, Aspidion is

established on remains of the seed-bearing disc and related toPeltaspermum, but as it is exposed on the abaxial surface, no seeds

or scars are visible.

Lopadiangium Zhao in Zhao, Mo, Zhang and Yao, 1980.

According to the emended diagnosis by Gomankov and Meyen

(1986), Lopadiangium should be used only for round female seed-

bearing discs of peltaspermalean affinity that cannot be studied in

detail, and where seed scars are not clearly visible. Disc margins

can be dissected to a variable extent, sometimes forming well-

developed lobes. It was also mentioned (Gomankov and Meyen,

1986) that the Lopadiangium seed-bearing discs possess seeds

adaxially attached to a disc shield around a central stalk of the disc.

In the Chinese original text (Zhao et al., 1980), Zhao described three

seed-bearing discs of Lopadiangium attached to one stalk and

forming a head-like aggregation. Autunia Krasser emend. Kerp, 1988. This genus has been

promoted up to the natural status. It includes both fan-shaped

seed-bearing stalked megasporophylls spirally attached to fertile

axis and compound pinnate leaves of callipterid morphology (Kerp,

1988). Initially known only from Europe (Kerp, 1982; Barthel,

2006) and North America (DiMichele et al., 2005), Autunia-typefructifications were reported from low-latitude Permian floras of

China (Wang, 1997) and Sumatra, Indonesia, where they were also

associated with callipterid leaves (Booi et al., 2009: pl. III, fig. 3a). Sandrewia

Mamay, 1975. This genus was initially misinter-

preted as a Vojnovskyalean reproductive organ, but was later

reinterpreted as a peltasperm female fructification (Kerp, 1988;

DiMichele et al., 2005). It is very close to Autunia Krasser and can be

regarded as its younger synonym (DiMichele et al., 2005).

Autuniopsis Poort and Kerp, 1990. The following diagnosis was

proposed for this genus in the original description: ‘‘Petiolate, fan-

shaped, bilaterally symmetrical ovule-bearing structures, with ribs

radiating from the petiole and a crenulate anterior margin’’ (Poort

and Kerp, 1990: p. 206). This genus is not properly described and

interpreted yet, and requires additional study.Meyenopteris Poort and Kerp, 1990. The original diagnosis of

this genus was for both female organs and leaves. The female

Fig. 8.

Vetlugospermum

rombicum

nov.

gen.,

nov.

sp.,

Spasskoe

locality. 1, 2,

spec.

4851/162a; 3,

spec.

4851/163e; 4,

spec.

4851/165.

Scale

bars:

1

cm.





reproductive organs consist of fertile axes bearing bilaterally

symmetrically stalked lobate megasporophylls with fan venation

(Poort and Kerp, 1990: p. 204). Each megasporophyll bears two

seeds (ovules), attached to one and the same side of themegasporophyll. These seed-bearing organs were originally

attributed to Peltaspermum and described as P. thomasii Harris.

According to Anderson and Anderson (2003: p. 151), the original

specimen of P. thomasii happens to have two seeds with the rest of

them missing. Anderson and Anderson (2003: p. 148) consider

Meyenopteris as a synonym of Peltaspermum. But later Meyenopteris

is considered by the same authors as a natural-genus belonging to

Peltaspermaceae (Anderson et al., 2007: p. 168).

Shenzhouspermum Yang, Xie and Wu, 2006. In the first citation

of this genus in the protolog (Yang, 2006: p. 273), another spelling

was used (Shenzhouapermum), but it was an obvious misspelling

because throughout the text it is spelt as Shenzhouspermum. The

features distinguishing this genus from Peltaspermum, according to

Yang (2006), are the bifurcating main fertile axes, trichotomizingof lateral fertile axes, and deep dissection of the seed-bearing discs

into long prominent lobes, in contrast to Lopadiangium Zhao. Seeds

of Shenzhouspermum are sessile, with a compylotropus nucellar

beak (Yang, 2006: p. 274).

VETLUGOSPERMACEAE nov. fam. NaugolnykhVetlugospermum nov. gen. Naugolnykh. Diagnosis, compari-

son, and general description are in the descriptive section of this

paper.Navipelta

Karasev, 2009. The seed-bearing organs assigned to

this genus have many uncommon and peculiar morphological

features and are clearly separated from other genera of the

Peltaspermaceae, except Vetlugospermum. However, the interpre-

tation of Navipelta and the orientation of several specimens from

the type collection (Karasev, 2009:pl. 17, fig. 7; pl. 18, fig. 3) are not

clear. The most peculiar feature of Navipelta is its bilateral

symmetry. Besides that, the seed-bearing shields of Navipelta

are considerably thicker than classic Peltaspermum. The Peltas-

permum seed-bearing discs quite often include resin bodies, round

in

shape

and

disposed

inside

the

mesophyll

layer

(Gomankov

andMeyen, 1986; Naugolnykh and Kerp, 1996). In contrast to that,

Navipelta has a very well-developed system of simple or bifurcated

Fig. 9.

Comparative

morphology

of

Peltaspermaceae

(A,

B),

Vetlugospermaceae

(C,

D),

and

Angaropeltaceae

(E–G)

megasporophylls. A.

Peltaspermum

sp.,

isolated

megasporophyll

disc

with

seeds

attached

(based

on

reconstruction

by

Harris,

1932). B.

Peltaspermum

racemose

aggregations

of

megasporophylls

with

deeply

dissected

discs

showing well-developed finger-like marginal lobes, based on Peltaspermum sp. from the Upper Permian deposits of Pechora coal basin. C. Navipelta (based on reconstruction

published by Karasev, 2009: fig. 1, 2), C1, cross section; Upper Permian of the Russian platform, Nedubrovo locality. D. Vetlugospermum, D1, cross section and reconstruction of

racemose aggregation of megasporophyll shields attached to a fertile axis; Lower Triassic of the Russian platform. E. Angaropeltum (formerly Cardiolepis; based on Meyen’s

reconstruction;

Meyen,

1982,

1984),

Upper

Permian,

Kazanian

stage,

Pechora

coal

basin. F.

Sylvocarpus

(based

on

Naugolnykh,

2008: fig.

2C,

fig.

3B),

Lower

Permian,

Kungurian stage, Middle Cis-Urals. G . Permoxylocarpus (based on Naugolnykh, 2007b: fig. 70–72, pl. XXXVII, fig. 4; pl. XXXVIII, fig. 1-3), Lower Permian, Kungurian stage,

Middle Cis-Urals.





resin channels located between conducting strands coming to seed

scars (Karasev, 2009).

ANGAROPELTACEAE Doweld, 2001 (originally Angaropeltidia-

ceae, etymologically incorrect)

Original diagnosis of this family was given (Doweld, 2001) in

brief: ‘‘Peltoida pedicellata, capsuloidea, ovules numerosis, laminae

affixis, cavum clausum’’. As was shown above, the cavity inside thecapsule of angaropeltidians is not completely closed, maybe with

just one exception (Sylvocarpus armatus Naugolnykh, 2008). But

even Sylvocarpus opened its seed-bearing capsule for seed

dissemination. Thus, the diagnosis of the Angaropeltidaceae family

should be emended as follows: ‘‘Gymnosperms of peltaspermalean

affinity with spherical or elliptical seed-bearing capsules with a

central

stalk

and

numerous

ovules/seeds

attached

to

adaxial

surface of capsule. Capsule cavity closed or semi-closed’’. Most of

the angaropeltidians had simple lanceolate entire-margined leaves

attributed to the genera Phylladoderma Zalessky and Praephylla-

doderma Naugolnykh.

Angaropeltum Doweld, 2001 (formerly Cardiolepis Neuburg,

1965; general discussion of the morphology is in Meyen, 1982,

1984). Spherical semi-closed capsules with smooth surfacecharacteristic of this genus. The capsules produced very peculiar

seeds with long attenuate micropyles slightly curved outwards.

Predecessors of Angaropeltum (Sylvocarpus and Permoxylocarpus

genera) most probably had less specialized seeds. Associated

leaves belong to the genus Phylladoderma.

Sylvocarpus Naugolnykh, 2008. Peltate seed-bearing capsules

of this genus consist of umbrella-shaped shields with margins

considerably curved downwards. The capsule surface is smooth,

with a small shallow depression located in the capsule’s upper part

just above the place where the stalk was attached to the lower

(adaxial) surface of the capsule’s shield. There are five round or

elliptical seed scars around the stalk on lower (adaxial) surface of

the capsule (Naugolnykh, 2008: p. 433). Associated leaves are

unknown.Permoxylocarpus

Naugolnykh, 2007b. The female reproductive

organs of this genus consist of peltate discs of umbrella-like shape

with central stalk. Margins of disc are curved downward

considerably and form a seed-including capsule. The outer surface

of the disc (capsule) is covered by smooth but distinct radial ribs

corresponding to the position of seeds. Marginal parts of the disc

bear concentric folds. Each capsule includes 14 to 16 ovules (seeds)

around the central stalk. Seeds on one side of the disc can be

undeveloped, causing the asymmetrical shape of some specimens.

Associated leaves belong to the genus Praephylladoderma genus

(Naugolnykh, 2007b; Naugolnykh and Oskolski, 2010).

6. Conclusions

The taxonomic composition of the Peltaspermales has been

discussed. The suggested concept of this order as a natural group is

based on the following characters:

the female reproductive organs are seed-bearing discs (=

ovuliferous discs, peltate megasporophylls) of flattened shape

(Peltaspermaceae Thomas, 1933), bilaterally symmetrical mega-

sporophylls with an adaxially attached central stalk (Vetlugos-

permaceae nov. fam. Naugolnykh), or seed-bearing capsules of

spherical shape (characteristic of Angaropeltaceae nov. emend.

Doweld, 2001);

the seed-bearing organs were attached to a fertile axis and formed

compound compact or loose aggregations, mostly cone-like;

the polliniferous organs (= male fructifications) consist of thenumerous pollen sacs fused by their bases into rosette-like

structures;

the polliniferous organs were attached to the fertile axes and

formed loose spicate aggregations;

the leaves are basically compound pinnate (Callipteris/Rhachi-

phyllum, Lepidopteris, Scytophyllum), but, as a result of reduction,

can be simple pinnate (Comia, Compsopteris, Glenopteris), or even

simple lanceolate (Pursongia/Tatarina). The various cases of such

leaf

reduction

could

be

due

to

ecological,

ontogenetical

orphylogenetical reasons.

Leaves of variable shape can be monopinnate at the base and

compound pinnate in the middle or apical parts of the frond. Such

combined leaves could probably be formed because of changing

environmental conditions, especially due to fluctuation of humidi-

ty or aridization (Naugolnykh, 1998).

The seed-bearing organs of Angaropeltaceae were almost

spherical in shape with the seeds/ovules inside the capsule, in

contrast to classic peltasperm seed-bearing discs. The most ancient,

but morphologically advanced angaropeltians were reported from

the uppermost LowerPermian (Kungurian) of the Urals. These plants

were represented by two genera (Permoxylocarpus and Sylvocarpus;

Naugolnykh,

2007b,

2008) established

on

female

fructifications.Associated lanceolate leaves with parallelodrom venation were

described as Praephylladoderma (Naugolnykh, 2007b).

The morphogenetic analysis of the Permian and Triassic

peltasperm taxa has revealed an evolutionary trend towards

forming more specialized female reproductive organs from

flattened ovuliferous discs (Peltaspermum) to semi-closed (Per-

moxylocarpus) or almost completely closed (Sylvocarus, Angar-

opeltum) seed-bearing capsules, that could reflect an increased

efficiency of reproduction and a more effective protection of the

ovules/seeds (Naugolnykh, 2008). This adaptation, possibly related

to the Permo-Triassic ecosystem transformation, was a selective

answer of peltasperm taxa for protecting the seeds. This trend of

peltasperm seed-bearing organ specialization from open discs to

enclosed capsules may be linked to gradual shift from anemophily

to entomophily in peltasperm evolution (Naugolnykh and

Oskolski, 2010).

Acknowledgments

The author expresses his gratitude to Prof. W.A. DiMichele

(Smithsonian Institution, Washington, DC, USA) and Dr. A.B.

Zamuner (La Facultad de Ciencias Naturales y Museo, La Plata,

Argentina) for reviewing the manuscript and providing very

helpful advices (Prof. DiMichele suggested the expression

‘‘agglomerative approach’’ used in this paper); to Dr. E.V. Karasev

(Palaeontological Institute of Russian Academy of Sciences,

Moscow, Russia) for providing access to the type collection of

Navipelta; to Dr. H.M. Anderson (Dorigo, Australia) for her very

valuable advice, linguistic help and important discussion of peltasperm morphology and systematics; and to Dr. M. Philippe

(Lyon, France) for valuable editorial suggestions. The study was

supported by grant 11-05-92692-INDa of the Russian Fund for

Basic Research.

References

Anderson, J.M., Anderson, H.M., 2003. Heyday of the gymnosperms: systematics andbiodiversity of the Late Triassic Molteno fructifications. National BotanicalInstitute,

Pretoria.Anderson, J.M., Anderson, H.M., Cleal, C.J., 2007. Brief history of the gymnosperms:

classification, biodiversity, phytogeography and ecology. National BotanicalInstitute, Pretoria.

Barthel,

M.,

2001.

Arnhardtia

sheibei

(Gothan)

Haubold

und

Kerp

und

andereRotliegend-Peltaspermaceen–Wege und Irrwege ihrer Erforschung. Hallesches

Jahrbuch

Geowissenschaften

23,

1–8.Barthel,

M.,2006.

Die

Rotliegendflora

des

Thueringer

Waldes.

Teil

4:

Farnsamer

undFarnlaub unbekannter taxonomischer Stellung. Veroffentlichungen Naturhis-torisches Museum Schleusingen 21, 33–72.




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Vetlugospermum and Vetlugospermaceae: A new genus and family of peltasperms from the Lower Triassic of Moscow syneclise (Russia)