Review of Palaeobotany and Palynology 210 (2014) 77–88

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Review of Palaeobotany and Palynology

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The Mesozoic genus Protophyllocladus Berry (Pinopsida)

Natalya Nosova, Lena GolovnevaKomarov Botanical Institute RAN, ul. Prof. Popova, 2, St. Petersburg 197376, Russia

E-mail address: natanosova@gmail.com (N. Nosova).

http://dx.doi.org/10.1016/j.revpalbo.2014.07.0030034-6667/© 2014 Elsevier B.V. All rights reserved.

a b s t r a c t

a r t i c l e i n f o

Article history:Received 15 March 2014Received in revised form 8 July 2014Accepted 10 July 2014Available online 30 July 2014

Keywords:ProtophyllocladusConiferCretaceousPhyllocladesEpidermal structure

Morphological and epidermal characters of Protophyllocladus Berry are documented in detail based on the inves-tigation of specimens from the Cretaceous ofwesternGreenland, western Siberia and Sakhalin (Russian Far East).Two new species, Protophyllocladus magathianus Nosova sp. nov. from the Arkovo Formation (Coniacian) ofSakhalin and P. groenlandicus Nosova sp. nov. from the Atane Formation (Albian – Cenomanian) of westernGreenland, are described. The new data on the epidermal structures of phylloclades of this genus allow us toemend the generic diagnosis. The morphology and epidermal features of Protophyllocladus are similar to thoseof the modern genus Phyllocladus Richard, suggesting the podocarpaceous affinity of Protophyllocladus.

© 2014 Elsevier B.V. All rights reserved.

1. Introduction

The genus Protophyllocladus Berry was established for the coniferphylloclades from Upper Cretaceous (Cenomanian) deposits of theDakota Formation, Kansas, USA (Berry, 1903). Originally, Berry includedthree species in this genus: Protophyllocladus subintegrifolius(Lesquereux) Berry, Protophyllocladus lanceolatus (Knowlton) Berry,and Protophyllocladus polymorphus (Lesquereux) Berry. These specieshad been previously attributed to the genera Thinnfeldia Ettingshausen(Corystospermales), Salisburia Smith (Ginkgoales), and PhyllocladusRichard (Pinopsida) (Lesquereux, 1868, 1874, 1878, 1892; Hollick,1898; Knowlton, 1893, et al.). Later, Berry described Protophyllocladuslobatus Berry from the Late Cretaceous Magothy Formation, Maryland,USA (Berry, 1911a) and Black Creek Formation, South Carolina, USA(Berry, 1914). Two additional species from the Upper Cretaceous ofAlaska (the Kaltag Formation) were described by Hollick (1930) asProtophyllocladus obesus Hollick and Protophyllocladus simplex Hollick.

The remains of Protophyllocladuswere recorded from the Cretaceousof the United States and southwestern Canada (Berry, 1903, 1907,1911a,b, 1914; Hollick, 1930; Bell, 1957, 1963), Western Greenland(Seward and Conway, 1935; Boyd, 1992), Serbia (Djordjević-Milutinović, 2010), Romania (Givulescu, 1968), Portugal (Teixeira,1950), Kazakhstan (Samsonov, 1966; Shilin, 1986), Japan (Tanai,1979), northeastern Russia (Kryshtofovich, 1918, 1920, 1937;Kryshtofovich and Baikovskaja, 1960; Krassilov, 1979; Samylina, 1988;German and Lebedev, 1991), and western Siberia, Russia (Lebedev,1962; Golovneva and Nosova, 2012). The strata containing remains of

Protophyllocladus are usually dated as Albian toMaastrichtian, however,in Serbia and Portugal they are regarded as to be Aptian–Albian in age(Teixeira, 1950; Djordjević-Milutinović, 2010).

Protophyllocladus phylloclades exhibit considerable variability.Therefore, the species cannot be differentiated based on their morpholog-ical features only. Kryshtofovich united all species of Protophyllocladus,except for Protophyllocladus lobatus, under the name of Protophyllocladuspolymorphus (Kryshtofovich, 1937; Kryshtofovich and Baikovskaja,1960).However, Tanai (1979)determined that thenameProtophyllocladussubintegrifolius has a priority over P. polymorphus, and united variousspecies under this name.

In spite of numerous findings, the epidermal structure ofProtophyllocladus remains insufficiently studied. The type material ofProtophyllocladus subintegrifolius from the Dakota Formation of Kansashas no cuticle. When describing the remains of this species from theTuronian Raritan Formation of New Jersey Berry indicated that “The sto-mata are of the common oval type with two sausage-shaped guardcells… They are small but fairly numerous and are equally commonon both surfaces of the leaf… They are not arranged in rows…” (Berry,1907: p. 90–91). The structure of one stoma was briefly described forP. subintegrifolius from Greenland (Seward and Conway, 1935).Finally, only several ordinary epidermal cells of the phylloclades ofP. subintegrifolius from the Upper Cretaceous of Japan have beenfigured by Tanai (1979).

The epidermal structure of the phylloclades from the Upper Creta-ceous of Sakhalin (Far East, Russia), described as Protophyllocladussachalinensis (Kryshtofovich et Baikovskaja) Krassilov, was studied inmore detail (Krassilov, 1979). However, P. sachalinensis is not a validtaxon, since its basionym (Thinnfeldia sachalinensis Kryshtofovich etBaikovskaja (Kryshtofovich and Baikovskaja, 1960) had been publishedwithout typification (McNeil et al., 2012, art. 40.1).

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A new occurrence of Protophyllocladuswith a well-preserved cuticlehas been found in the Cenomanian deposits of the Simonovo Formationnear Seversk (Tomsk oblast', western Siberia). Based on their peculiarepidermal structure, they were described as Protophyllocladusvachrameevii Nosova et Golovneva (Golovneva and Nosova, 2012).

We restudied the specimens of Protophyllocladus from the AtaneFormation of western Greenland described by Seward and Conway(1935) and from Kryshtofovich's collections from Sakhalin. The epider-mal structures of these phylloclades differ from previously describedspecies so that we propose to erect two new species Protophyllocladusmagathianus Nosova sp. nov. and Protophyllocladus groenlandicusNosova sp. nov.

2. Materials and methods

2.1. The material from Sakhalin

Specimenswere collected byKryshtofovich and Polevoy on the coastof the Tatar Strait, western Sakhalin in 1917–1929. The first findingswere described by Kryshtofovich from Mgach mine (now Mgachi vil-lage) as Protophyllocladus subintegrifolius (Kryshtofovich, 1918, 1920)and Protophyllocladus polymorphus (Kryshtofovich, 1937). The phyllo-clades were later discovered in many other localities near Mgachi:Mangiday river mouth, mine Polovinka, Shustova valley, Vladimirovkariver, the Naynay river, Nazarovsky spring, and Tangi river mouth(Kryshtofovich and Baikovskaja, 1960).

Kryshtofovich attributed these localities to the Gilyak Series anddated fossiliferous deposits as Cenomanian–Turonian (Kryshtofovich,1918, 1920). These deposits are now included in the Arkovo Formation,with its age estimated as Coniacian–early Santonian (Krassilov, 1979) orConiacian (Zonova and Yagt-Yazykova, 2008).

The greatest part of the Kryshtofovich's collections is stored at theChernyshov Central Geological Survey and Research Museum in St.Petersburg, Russia (coll. CNIGRM 2069 and 6256). Specimens ofProtophyllocladus are from the following localities: loc. 422, 444,Mgachi (51°02′ N, 142°15′ E); loc. 449, 450, Mangiday river mouth(51°05′ N, 142°15′ E) and loc. 61, 373, mine Polovinka (50°56′ N,142°15′ E). Tables 1 and 2 show Kryshtofovich's specimen numbers(Kryshtofovich, 1937; Kryshtofovich and Baikovskaja, 1960) andthe numbers under which they are stored in the Chernyshov CentralGeological Survey and Research Museum.

Table 1Equivalence between specimen numbers by Kryshtofovich (1937) and the numbers of CNIGR

Kryshtofovich, 1937

Specimen Name

422-1 Protophyllocladus polymorphus422-2 Protophyllocladus polymorphus422-3 (?) Protophyllocladus polymorphus422-3 Protophyllocladus polymorphus422-4 Protophyllocladus polymorphus422-5 Protophyllocladus polymorphus422-6 Protophyllocladus polymorphus422-6 Protophyllocladus polymorphus422-7 Protophyllocladus polymorphus422-8a Protophyllocladus polymorphus422-8b Protophyllocladus polymorphus422-9 Protophyllocladus polymorphus422-10a, b Protophyllocladus polymorphus422-11 Protophyllocladus polymorphus422-14 Protophyllocladus polymorphus422-32а, b Protophyllocladus polymorphus422-53 Protophyllocladus polymorphus422-69 Protophyllocladus polymorphus422-70 Protophyllocladus polymorphus

Some of the specimens, collected by Kryshtofovich in locality 422,are kept at the Komarov Botanical Institute of the Russian Academy ofSciences, St. Petersburg (collection BIN 140).

About 30 specimens of phylloclades were examined. Most of themare imprints with partially preserved cuticle fragments. The cuticle isfragile and usually disintegrates during maceration. The epidermalstructure of nine specimens was studied.

2.2. The material from Western Greenland

The material was collected from the locality Atanikerdluk, south ofthe Nûgssuaq peninsula (~70°00′ N, 51°56′ W) from the Albian–Cenomanian deposits of the Albian–earliest Campanian Atane Forma-tion (Pedersen and Pulveraft, 1992; Dam et al., 2000). The specimensare stored at the Section of Palaeobotany, Swedish Museum of NaturalHistory (Riksmuseet), Stockholm (specimen numbers with the prefix S).Seward and Conway (1935) described two species Protophyllocladussubintegrifolius (specimen S108077) and Protophyllocladus polymorphus(specimen S108078). We studied the epidermal structure of specimenS108077. Based on the results, we propose to erect a new speciesProtophyllocladus groenlandicus Nosova sp. nov. The cuticle of thespecimen S108078 was destroyed by fungi (Pl. I, 12).

2.3. The material from Western Siberia

The remains of Protophyllocladus vachrameevii (Golovneva andNosova, 2012) were found in the Cenomanian deposits of the SimonovoFormation near Seversk (Tomsk oblast'). The specimens are kept at theTomsk Polytechnic University, Tomsk (collection TPI, spec. S17a, S18).

All studied cuticle slides, and SEM stubs are kept at the Laboratory ofPalaeobotany of the Komarov Botanical Institute.

Cuticles were prepared according to the standard proceduresoutlined by Kerp (1990). The structure of the epidermis was studiedwith a light microscope (LM) and a scanning electron microscope(SEM) JSM-6390 LA.

3. Systematic descriptions

Pinopsida Burnett, 1835Family incertae familiaeProtophyllocladus Berry, 1903Type species: Protophyllocladus subintegrifolius (LESQUEREUX) Berry

Museum.

CNIGR Museum, collection 2069

Illustrations Specimen

Pl. IX, fig. 3 86Pl. IX, fig. 4 80Pl. IX, fig. 5 lostPl. X, fig. 1 87Pl. IX, fig. 6 78Not figured 91Pl. IX, fig. 7 88aPl. IX, fig. 8 88bNot figured 70Not figured 89Pl. X, fig. 2 89aPl. X, fig. 3 63Not figured 93a, bNot figured 94Not figured 95Not figured 92aPl. X, fig. 4 5Pl. X, fig. 5 90, lostPl. X, fig. 6 62

Table 2Equivalence between specimen numbers by Kryshtofovich and Baikovskaja (1960) and the numbers of CNIGR Museum.

Kryshtofovich and Baikovskaja, 1960 CNIGR Museum, collection 6256

Specimen Name Illustrations Specimen

373b-3 Protophyllocladus polymorphus Not figured 244444-1 Protophyllocladus polymorphus Not figured 240449-8 Protophyllocladus polymorphus Not figured 241449-10449-11449-12449-14449-9 Protophyllocladus polymorphus Not figured 242449-13449-16 Protophyllocladus polymorphus Pl. XI, fig. 5 104, lost449-17 Protophyllocladus polymorphus Pl. XI, fig. 3 102449-17 Protophyllocladus polymorphus Not figured 102а449-18 Protophyllocladus polymorphus Pl. XI, fig. 2 101449 Protophyllocladus polymorphus Pl. XI, fig. 4 10361h-1 Protophyllocladus polymorphus Not figured 24361h-6 Protophyllocladus polymorphus Not figured 27661-5 Protophyllocladus polymorphus Pl. XIII, fig. 2 105450-22 Thinnfeldia sachalinensis Pl. III, fig. 6 63450-22а Thinnfeldia sachalinensis Pl. III, fig. 1 64

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Emended generic diagnosis. Phylloclades of coriaceous texture, arrangedalternately or subopposite, simple or pinnatilobate linear to ovate-lanceolate in outline, slightly petiolate, with cuneate decurrent baseand acute, obtuse, rounded or emarginated apex. Margins lobate, cre-nate, undulate or entire. Midrib stout near the base and becoming indis-cernible toward the apex. Numerous thin lateral veins leave the midribat an acute angle, sometimes bifurcated close to themidrib. Stomata nu-merous on both surfaces, or only on the abaxial one, scattered randomlyor in indistinct rows or bands, oriented longitudinally to irregularly.Subsidiary cells 4–6. Guard cells are slightly sunken, narrow.Protophyllocladus magathianus Nosova sp. nov.(Plates I, 1–11, 14–16; II; IV, 1–5, 7, 13; V, 8–12; Fig. 1 A, B)1918 Protophyllocladus subintegrifolius (LESQUEREUX) Berry —

Kryshtofovich, p. 41, text-fig. 6.1920 Protophyllocladus subintegrifolius (LESQUEREUX) Berry —

Kryshtofovich, p. 488.1937Protophyllocladus polymorphus (LESQUEREUX) Berry—Kryshtofovich,p. 67, plate IX, 3–8; plate X, 1–6.1960 Protophyllocladus polymorphus (LESQUEREUX) Berry—Kryshtofovichand Baikovskaja, p. 50, plate XI, 2–5a; plate XIII, 2.Holotype: coll. BIN 140, spec. 16(1), Plate I, 7.Etymology — name of the locality Mgachi.Type locality: Mgachi, coast of the Tatar Strait, western Sakhalin.Type stratum and age: Arkovo Formation, Coniacian, Late Cretaceous.Other localities: Mangiday river mouth and mine Polovinka, westernSakhalin.Material studied: coll. BIN 140, spec. 6, 16(1), 16(6), 16(10); coll.CNIGRM 2069: spec. 5, 62, 63, 70, 78, 80, 86–89a, and 91–95; coll.CNIGRM 6256: spec. 101, 102, 102a, 103, 105, 240–244, and 276.Diagnosis. Phylloclades amphistomatic, with sporadic stomataoccasionally occurring on the adaxial epidermis, more often near themargins. Adaxial cuticle thicker than the abaxial. Cells of the adaxialepidermis quadrangular, short or polygonal, isodiametric. Cells of theabaxial epidermis quadrangular to polygonal, elongated to short.Periclinal cell walls smooth. Stomata on the abaxial epidermis scatteredrandomly or in indistinct rows, oriented longitudinally, obliquely orirregularly.Description. The material comprises numerous phylloclades, eitherdetached or attached to the axis (Kryshtofovich, 1937: pl. IX, 6;Kryshtofovich and Baikovskaja, 1960: pl. XI, 5; pl. I, 7). Axes are 2–3mm in diameter. The phylloclades are arranged alternately orsubopposite, from oblong–lanceolate to oblong–obovate or oval in out-line, with cuneate decurrent base and short petiole. The apex is acute

(Pl. I, 11), obtuse (Pl. I, 9), rounded (Pl. I, 4), or emarginate(Kryshtofovich, 1937: pl. IX, 3). The margins are undulate to crenateor entire with rare teeth about 2 mm long. The phylloclades are 2–7cm wide, 7–9 cm long, the longest preserved fragment reaching 12cm. Themidrib is straight and stout near the base of phylloclade and be-comes indiscernible toward the apex. The lateral veins are numerousand thin, and they leave the midrib at an acute angle, sometimes bifur-cate close to the midrib (Fig. 1).

The adaxial cuticle is thicker than the abaxial one. The phyllocladesare amphistomatic. Some fragments of the adaxial epidermis lackstomata, while the stomata occur occasionally in some cuticle piecesof the adaxial side (Pl. II, 2). There are fragments where stomata occurmore often on the adaxial epidermis near the margins (Pl. II, 1). Thecells of the adaxial epidermis are quadrangular, short or polygonal,and isodiametric; they are elongated, quadrangular to polygonal nearthe margins and along the midrib. The anticlinal cell walls are straightand thick (2–4 μm thick), the periclinal walls are smooth, and the cellangles are rounded.

On the abaxial epidermis, the stomata are scattered randomly orform indistinct rows (Pl. II, 1, 4–6; IV, 1). Cells of the abaxial epidermisare quadrangular to polygonal and elongated to short. The anticlinalcell walls are straight, 1–2.5 μm thick, and the periclinal ones aresmooth. The cell angles are rounded. Cell sizes are 7–23 × 13–56 μm.The stomata are oriented longitudinally, obliquely, or irregularly.There are adjacent stomatal complexes with shared subsidiary cells.The stomatal complexes are incompletely amphicyclic, with 4–6subsidiary cells. Unlike in the adaxial side, on the abaxial one they aresometimes stronger cutinized than the ordinary epidermal cells (Pl. II,4, 5, 8, 11; V, 10, 12). There are usually two polar and two or threewing-shaped lateral subsidiary cells. The polar subsidiary cells aretypically short. The stomatal complexes are rounded, rarely oval inoutline. The dimensions of the stomatal complexes vary in therange 21–56 × 51–91 μm. The guard cells are slightly sunken, narrow,wing-shaped, with polar appendages up to 6–10 μm long (Pl. IV, 2–5, 7).The dimensions of the guard cells without polar appendages are16–34 μm long and 8–18 μm wide.Comparison: The phylloclades of Protophyllocladus magathianus aremorphologically similar to those of Protophyllocladus subintegrifolius.Unfortunately, the epidermal structure of the type specimen ofP. subintegrifolius from Kansas remains unknown. For phyllocladesof Protophyllocladus from New Jersey (P. subintegrifolius, Berry, 1907,our Protophyllocladus sp., see below), Berry gives only a brief descriptionof the stomatal topography and the guard cells (Berry, 1907). The

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presence of the numerous stomata on the both phylloclade surfacesreadily distinguishes thismaterial from Protophyllocladusmagathianuswith rare stomata on the adaxial side (Table 3). The phyllocladesof P. magathianus are larger than those of Protophyllocladusvachrameevii from western Siberia (Pl. I, 17, 18); they differ from thelatter by the lack of flattened papillae and cuticular ridges on periclinalcell walls (Pl. II, 1–12; III, 8–11; IV, 12; V, 12). Unlike in the new species,the phylloclades described by Krassilov as Protophyllocladussachalinensis have hair bases on the epidermal cells and their anticlinalcell walls are straight to undulate.Protophyllocladus groenlandicus Nosova sp. nov.(Plates I, 13; III, 1–7; IV, 6, 14)1935 Protophyllocladus subintegrifolius (LESQUEREUX) Berry — Sewardand Conway, p. 17, plate 6, 30.Holotype: SwedishMuseum of Natural History, Section of Palaeobotany,coll. Greenland expedition, 1883, spec. S108077, Seward and Conway,1935, p. 17, plate 6, 30; present paper, Plate I, 13.Etymology — from Greenland.Type locality: Atanikerdluk, Nûgssuaq peninsula, western Greenland.Type stratum and age: Atane Formation, Albian — Cenomanian,Cretaceous.Material studied: spec. S108077 (holotype).Diagnosis. Phylloclades amphistomatic. Adaxial cuticle thicker than theabaxial one. Cells of the adaxial and abaxial epidermis quadrangular topolygonal, elongate to short. Periclinal cell walls smooth on the adaxialsurface and with several flattened papillae on most of cells on theabaxial surface. Stomata scattered randomly on both surfaces, orientedlongitudinally to obliquely on the adaxial epidermis, and longitudinallyto irregularly on the abaxial epidermis. Inner anticlinal walls of the sub-sidiary cells sometimes thickened, forming a cuticular rim around thestomatal pit.

Description. The terminal phylloclade tapers downwards into awinged axis to which two smaller phylloclades are attached. The axisis 1.5–2mm in diameter. The phylloclades are lanceolate in outline, nar-rowly cuneate to the short petiole. The apex is unknown. The marginsare entire to undulate, dentate on the terminal phylloclade, with teethabout 1 mm long. The phylloclades are 1.7–2.4 cm wide, the longestpreserved phylloclade reaching 5.5 cm. The midrib is stout. The lateralveins are numerous and thin, and they leave the midrib at an acuteangle and bifurcate close to the midrib. The adaxial cuticle is thickerthan the abaxial one.

The phylloclades are amphistomaticwith stomata scattered randomlyon both surfaces; in some fragments they occur rarely on the adaxialside. Stomata are oriented longitudinally to obliquely on the adaxialepidermis, and longitudinally to irregularly on the abaxial epidermis.Cells of the adaxial and abaxial epidermis are elongated, quadrangular;less often, they are short polygonal. Anticlinal cell walls are straight,

Plate I.

1–11, 14–16— Protophyllocladus magathianus Nosova from western Sakhalin, Russia, the Arko1–6, 10, 11 — coll. CNIGRM 2069: 1 — spec. 91, 2 — spec. 89, 3 — spec. 89a, 4–87,7, 8 — coll. BIN 140: 7 — spec. 16(1), holotype, 8 — spec. 16(6);9, 14–16— coll. CNIGRM 6256: 9 — spec. 101, 14 — spec. 102; 15 — spec. 105; 16

12 — Protophyllocladus polymorphus (Lesquereux) Berry (=Protophyllocladus subintCenomanian, phylloclade fragment, spec. S108078;

13— Protophyllocladus groenlandicus Nosova from western Greenland, the Atane Forma17, 18— Protophyllocladus vachrameevii Nosova et Golovneva from Tomsk oblast', weste

TPI: 17 — spec. S17a, 18 — spec. S18;19–21— Sachalinia sachalinensis Vachrameev fromwestern Sakhalin, Russia, the Arkovo Fo

spec. 64. Scale bars 1 mm.

Plate II. (see on page 6)1–12— Protophyllocladus magathianusNosova fromwestern Sakhalin, Russia, the Arkovo F

CNIGRM2069, spec. 5; 2— adaxial surface with one stoma, LM, coll. BIN 140, spec.140, spec. 16(1), holotype; 9 — coll. CNIGRM 2069, spec. 88; 10, 11 — coll. CNIGRholotype; 5 — coll. CNIGRM 2069, spec. 78; 6 — coll. CNIGRM 2069, spec. 5. Scale

1–2.6 μm thick. Cell angles are rounded, less often acute. Periclinalcell walls are smooth on the adaxial surface (Pl. III, 2, 5–7) and with1–2(3) flattened papillae on most of the cells on the abaxial surface(Pl. III, 1, 3, 4). Cell sizes are 9–22 × 31–62 μm. Stomatal complexesare monocyclic to incompletely amphicyclic, with dimensions lying inthe range of 27–39 × 43–75 μm, and 4–6 subsidiary cells that are notstronger cutinized than the ordinary epidermal cells. There are usuallytwo polar and two or three wing-shaped lateral subsidiary cells. Thepolar subsidiary cells are more commonly elongate. The inner anticlinalwalls of the subsidiary cells sometimes are thickened, forming a cuticu-lar rim around the stomatal pit (Pl. IV, 14). The guard cells are slightlysunken, narrow, wing-shaped, with polar appendages up to 8 μm long(Pl. I, 3, 4; IV, 6). The guard cells without polar appendages are20–24 μm long and 11–15 μm wide.Comparison: The phylloclades of Protophyllocladus groenlandicus aremorphologically similar to those of Protophyllocladus subintegrifolius.The New Jersey material (P. subintegrifolius, Berry, 1907, ourProtophyllocladus sp., see below), differs from P. groenlandicus bythe absence of flattened papillae on the abaxial side. Unlike inProtophyllocladus magathianus, P. groenlandicus has a different cellshape of the adaxial side and flattened papillae on the abaxial side,and cutinization of the subsidiary cells of stomata is similar to theordinary cells. The presence of hair bases on the epidermal cells andundulated anticlinal cell walls distinguishes the phylloclades describedby Krassilov asProtophyllocladus sachalinensis from P. groenlandicus. Incontrast toProtophyllocladus vachrameevii fromSiberia (Pl. I, 17, 18; III,8–11; IV, 12), the phylloclades of P. groenlandicus are larger, the adaxialcuticle is thicker than the abaxial one, and the flattened papillae occuronly on the abaxial side (Table 3).

4. Discussion

4.1. Taxonomic remarks

Following Kryshtofovich (Kryshtofovich, 1937; Kryshtofovichand Baikovskaja, 1960) and Tanai (Tanai, 1979) we accept two spe-cies in Protophyllocladus for specimens exclusively described on thebasis ofmorphological characters: Protophyllocladus subintegrifolius andProtophyllocladus lobatus. The names Protophyllocladus polymorphus,Protophyllocladus lanceolatus, Protophyllocladus obesus andProtophyllocladus simplex are regarded as synonyms of P. subintegrifolius.According to Berry (1911a), P. lobatus differs from P. subintegrifoliusin having pinnatilobate phylloclades. In our view, the separationof the species P. lobatus requires an additional investigation,since the occasional development of secondary lobes is quite com-mon in modern Phyllocladus species. In addition, we have threespecies of Protophyllocladus characterized by epidermal structure:

vo Formation, Coniacian, phylloclade fragments:5 — spec. 88b, 6 — spec. 80, 10 — spec. 92a, 11 — spec. 88a;

— spec. 103;egrifolius (Lesquereux) Berry) from western Greenland, the Atane Formation, Albian–

tion, Albian–Cenomanian, branched axis with phylloclades, spec. S108077;rn Siberia, Russia, the Simonovo Formation, Cenomanian, phylloclade fragments, coll.

rmation, Coniacian, leaves: 19, 20— coll. CNIGRM 6256, spec. 63, 21— coll. CNIGRM 6256,

ormation, Coniacian: 1— abaxial (left) and adaxial (right) surfaces with stomata, LM, coll.16(1), holotype; 3, 7–12— stomata, LM: 3, 7, 12— coll. CNIGRM 2069, spec. 5; 8— coll. BINM 2069, spec. 78; 4–6 — abaxial surface with stomata, LM: 4 — coll. BIN 140, spec. 16(1),bars 50 μm.

Plate I.

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Plate II. (caption on page 4).

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Plate III.

1–7 — Protophyllocladus groenlandicus Nosova from western Greenland, the Atane Formation, Albian–Cenomanian: spec. S108077: 1, 3, 4 — stomata on the abaxial surface, LM;2, 5–7 — stomata on the adaxial surface, LM;

8–11— Protophyllocladus vachrameevii Nosova et Golovneva from Tomsk oblast', western Siberia, Russia, the Simonovo Formation, Cenomanian, flattened papillae on the anticlinalcell walls and stomata, LM, coll. TPI, spec. S18 (LM). Scale bars 50 μm.

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Protophyllocladus vachrameevii, Protophyllocladus magathianus,and Protophyllocladus groenlandicus.

The epidermal structure of the type specimen of Protophyllocladussubintegrifolius from Kansas remains unknown. The information aboutthe epidermal characters of the New Jersey phylloclades described asP. subintegrifolius (Berry, 1907) is scarce. Berry only provides a drawingof an epidermis fragment with stomata, as well as a brief description ofthe stomatal topography and the guard cells (Berry, 1907: p. 90–91). Amore detailed investigation of the New Jersey specimens using moremodern approach could contribute to fuller characterization of thesephylloclades in future. Thus, we suggest treating these findings asProtophyllocladus sp.

For the invalid name Protophyllocladus sachalinensis (see introduc-tion), Krassilov considered the name Thinnfeldia sachalinensis describedby Kryshtofovich and Baikovskaja (1960) to represent the basionym.When revising the material from the Kryshtofovich's collections fromSakhalin, we re-examined the leaves of T. sachalinensis. These leavesare pinnate, the midrib is well marked until the apex and secondaryveins are twice forked (Pl. I, 19–21). The cuticle of these leaves is notpreserved. The leaves of T. sachalinensis is morphologically similar tothe fern Sachalinia sachalinensis Vachrameev, described from thesame locality (Vakhrameev, 1968), and we refer the Kryshtofovich'sspecimens to this species. Later, S. sachalinensis was found in theUpper Cretaceous of Japan (Tanai, 1979).

Unfortunately, we could not restudy the Krassilov's specimens, de-scribed as Protophyllocladus sachalinensis from Sakhalin (Krassilov,1979). Krassilov mentioned the presence of anastomoses of secondaryveins in phylloclades and the hair bases on the epidermal cells(Krassilov, 1979: pl. XXIV, 8). However, these characters have notbeen noticed for Protophyllocladus. We suppose that the Krassilov'smaterial should not be attributed to the genus Protophyllocladus.

4.2. The epidermal features of Protophyllocladus

The studies of the epidermal structure of the phylloclades ofProtophyllocladus reveal the following features (Table 3). The cuticle ofboth phylloclade surfaces can be of equal thickness (Protophyllocladusvachrameevii) and thinner on the abaxial side (Protophyllocladusmagathianus, Protophyllocladus groenlandicus). Stomata can be numer-ous on both surfaces (P. vachrameevii, P. groenlandicus, Protophyllocladussp.) or only on the abaxial one, while sporadic stomata occasionally oc-curs on the adaxial surface (P. magathianus). Stomatal complexes aremonocyclic to incompletely amphicyclic. Stomata are orientedlongitudinally, obliquely to irregularly. Stomata are scattered randomly(P. groenlandicus, P. magathianus, Protophyllocladus sp.), or form indis-tinct rows (P. magathianus) or bands (P. vachrameevii). Periclinal cellwalls are either smooth (P. magathianus, Protophyllocladus sp.) or withcuticular thickenings (P. groenlandicus, P. vachrameevii). Most stomatalcomplexes have two or three wing-shaped lateral subsidiary cells

Plate IV.

1–5, 7, 13— Protophyllocladus magathianus Nosova from western Sakhalin, Russia, the Arkovo Fview, SEM, coll. BIN 140, spec. 16(1), holotype; 2— stomata on the abaxial surface,140, spec. 16(1), holotype; 5 — stoma, internal view, SEM, coll. BIN 140, spec. 16(

6, 14— Protophyllocladus groenlandicusNosova fromwestern Greenland, theAtane Formatexternal view, SEM; 8, 9, 12 — Protophyllocladus vachrameevii Nosova et GolovnevTPI, spec. S18: 8, 9 — stoma, internal view, SEM; 12 — stomata, flattened papillae

10, 11 — Phyllocladus aspleniifolius (Labillardière) Hooker f., herbarium from the Tasmania,

Plate V. (see on page 10)

1–3, 6— Phyllocladus aspleniifolius (Labillardière) Hooker f., herbarium from Tasmaniamata, LM; 3 — stoma, LM;

4, 5, 7 — Phyllocladus toatoaMolloy, herbarium from New Zealand: 4, 5 — stomata, LM; 7 —

8–12— ProtophyllocladusmagathianusNosova fromwestern Sakhalin, Russia, the Arkovo Fcoll. CNIGRM 2069, spec. 88; 10–12— stomata, LM, coll. CNIGRM 2069, spec. 78. S

and narrow guard cells. The inner anticlinal walls of the subsidiarycells sometimes are thickened, forming a cuticular rim around thestomatal pit.

Based on these epidermal characters, the diagnosis of Protophyllocladusis extended (see above).

4.3. Systematic affinities of Protophyllocladus

The systematic position of Protophyllocladus was previouslyunclear. Protophyllocladus polymorphus and Protophyllocladuslanceolatus were originally attributed to the genus Thinnfeldia(Pachypteris Brongniart according to Doludenko, 1971) (Knowlton,1893). However, there are significant differences in the morphologyand epidermal structure of the phylloclades of Protophyllocladus andthe leaves of Pachypteris (Corystospermales). Pachypteris leaves areonce or twice pinnate, petiolate, bearing pinna rachises or laminasegments (Harris, 1964). The venation is pinnate, with a clearmidvein and lateral veins forking 1–3 times (Doludenko, 1969).The midrib of the Protophyllocladus is stout in the basal part, and be-comes indiscernible toward the apex; lateral veins are numerous,closely spaced, thin, usually with no branching or sometimes bifur-cated close to the midrib. Stomatal complexes of Protophyllocladusdiffer considerably from those of Pachypteris, both in shape of theguard cells and in number and structure of subsidiary cells.Pachypteris stomata complexes include “poorly cutinized guardcells, subsidiary cells with different degree of proximal and distalcutinization, and non-specialized encircling cells, frequently formingan incomplete ring. Subsidiary cells are peculiar… and show eitherthin or thick cuticular banks (rings) on a proximal radial wall, adjoininga stomatal pit. They merge to form a proximal bank or a ring. The distalwalls of the subsidiary cells are oblique and have a ventral cuticularflange. This produces an effect of a second, dorsal ring of a stomawhen the cuticle is being examined under a light microscope”(Doludenko et al., 1998: p. 58).

Berry (1903) noticed the evident morphological similarity betweenphylloclades in Protophyllocladus and Phyllocladus (Podocarpaceae),but pointed to the larger size of phylloclades in the fossil genus. Howev-er, the dimensions of the phylloclades of Protophyllocladus vachrameevii(Pl. I, 17, 18) are comparable to those of some modern species ofPhyllocladus. Some other authors also considered placing Protophyllocladuswithin Podocarpaceae (Samsonov, 1966; Shilin, 1986; Samylina, 1988;Boyd, 1992).

To define the systematic position of Protophyllocladusmore precisely,we have studied the epidermal structure of some modern genera ofPodocarpaceae. Phylloclades of Protophyllocladus are morphologicallyvery similar to those of Phyllocladus. The structure of the stomatalcomplexes, their shape and size, and the shape of the guard cells ofProtophyllocladus resemble those of Phyllocladus (in particular,Phyllocladus aspleniifolius (Labillardière) Hooker f. (Pl. IV, 10, 11; V,

ormation, Coniacian: 1— adaxial (left) and abaxial (right) surfaces with stomata, internalinternal view, SEM, coll. CNIGRM2069, spec. 5; 3, 4, 7— stoma, internal view, SEM, coll. BIN6); 13 — stomata, external view, SEM, coll. BIN 140, spec. 16(1), holotype.ion, Albian–Cenomanian, spec. S108077: 6— stoma, internal view, SEM; 12— two stomata,a from Tomsk oblast', western Siberia, Russia, the Simonovo Formation, Cenomanian, coll.and cuticular ridges, external view, SEM.stomata, internal view, SEM. Scale bars: 1, 2, 12–50 μm; 3–11, 13, 14 — 10 μm.

: 1 — abaxial (left) and adaxial (right) surfaces, LM; 2 — adaxial surface with two sto-

abaxial surface, LM;ormation, Coniacian: 8— abaxial surfaces, LM, coll. CNIGRM 2069, spec. 88; 9— stoma, LM,cale bars 50 μm. (see on page 10)

Plate IV.

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Plate V. (caption on page 8).

86 N. Nosova, L. Golovneva / Review of Palaeobotany and Palynology 210 (2014) 77–88

Fig. 1. Interpretative drawings of Protophyllocladus magathianus Nosova, showingvenation pattern. A, phylloclade, coll. CNIGRM 2069, spec. 80. B, fragment of phylloclade,coll. CNIGRM 6256, spec. 102. Scale bars 1 mm.

87N. Nosova, L. Golovneva / Review of Palaeobotany and Palynology 210 (2014) 77–88

1–3, 6), Phyllocladus toatoa Molloy (Pl. V, 4, 5, 7) and Phyllocladusalpinus Hooker f. (Florin, 1931, Taf. 30, Fig. 9, 11)). Both genera arecharacterized by numerous or rare stomata on the adaxial side.Some species of Phyllocladus (e.g., P. aspleniifolius and P. toatoaMolloy),and most species of Protophyllocladus, have stomata not arranged indistinct rows or bands. However, unlike in Cretaceous phylloclades,stomata of Phyllocladus are oriented mainly longitudinally.

Modern species of Phyllocladus are known from Malaysia,Tasmania, and New Zealand. Fossil representatives of the Phyllocladusare recorded also only from the Southern Hemisphere: from theOligocene and Miocene of New Zealand, as well as from theOligocene of Australia. Pollen grains referred to Phyllocladus havebeen identified from Oligocene deposits of Australia, Tasmania,and Antarctica, as well as in Oligocene to Quaternary strata of NewZealand (Cookson and Pike, 1954; Cranwell, 1959; Florin, 1963;Hill, 1989; Pole, 1992).

Protophyllocladus was widely distributed in the Siberian–Canadianpalaeofloristic realm, being known from the Cretaceous of Alaska,northeastern Russia, western Siberia, Sakhalin, and Japan, as well as inthe Euro–Sinian palaeofloristic realm in Kazakhstan, Europe, Greenland,USA, and southwestern Canada.

5. Conclusions

Today, we accept two species in Protophyllocladus for specimensdescribed on the morphological characters only: Protophyllocladussubintegrifolius and Protophyllocladus lobatus; and four species

Table 3The epidermal characters of Protophyllocladus (“?” stands for “the data unavailable”).

Characters P. groenlandicus P. magathianus

Cuticle of the adaxial side thinner Yes YesStomata topography Random Indistinct rows, ranStomata on the adaxial side Not numerous or rare Rare, frequent near

phyllocladeStomata orientation on the adaxial side Longitudinal to oblique Sometimes longitudStomata orientation on the abaxial side Longitudinal to irregular Sometimes longitudCuticular thickenings of the periclinalcell walls

Flattened papillae on theabaxial side

No

Cuticular rim around the stomatal pit Yes/no NoAge Albian–Cenomanian ConiacianLocality Western Greenland

(Denmark)Sakhalin (Russia)

Reference This paper This paper

distinguished on the base of epidermal characters: Protophyllocladusvachrameevii, Protophyllocladus magathianus, Protophyllocladusgroenlandicus, and Protophyllocladus sp. The differences in epidermalstructure of fossil phylloclades and the similar morphology implythat the specific identifications of Protophyllocladus should be basedon epidermal characters, while specimens where such characters re-main unknown need to be described as P. subintegrifolius or P. lobatus,depending on their morphological features.

The genus Protophyllocladus bears a strong similarity with Phyllocladus,not only in morphology but also in the epidermal structure, whichfavors the podocarpaceous affinity of Protophyllocladus, despite thecurrent lack of findings of reproductive structures associated with thisfossil genus.

Acknowledgments

We are grateful to Dr. Else Marie Friis for the opportunity to workwith the Greenland material. The study was supported by the RussianFoundation for Basic Research (Project No. 13-04-01643-a).

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