Cainozoic Research, 10(1-2), pp. 23-34, July 2013 Early-middle Eocene faunal assemblages from the Soh area, north-central Iran, 1. Introduction and pteropods (Mollusca, Gastropoda, Thecosomata) Arie W. Janssen1*, John W.M. Jagt2, Mehdi Yazdi3, Ali Bahrami3 & Saforeh Sadri3

1Naturalis Biodiversity Center, P.O. Box 9517, 2300 RA Leiden, the Netherlands; e-mail: ajanssen@go.net.mt 2Natuurhistorisch Museum Maastricht, de Bosquetplein 6-7, 6211 KJ Maastricht, the Netherlands; e-mail: john.jagt@maastricht.nl

3Department of Geology, Faculty of Science, University of Isfahan, Iran; e-mails:Meh.yazdi@gmail.com; bah-rami_geo@yahoo.com

*Corresponding author Received 23 March 2012, revised version accepted 20 April 2013 In the Sarakeh Syncline (Soh area, north of Isfahan, north-central Iran), early and middle Eocene (Ypresian-Lutetian) clays, marls and limestone/marl intercalations have been sampled in two temporary trenches. From Trench-1 (Villa section) and Trench-2 (Estakhr sec-tion), eight c. 20 kg samples have been taken for micro- and macrofossil analysis. From the Estakhr section two additional samples, from 18 and 20 metres above the base of the section, which corresponds to the Paleocene-Eocene boundary, have yielded pteropods and bour-gueticrinid crinoids. Two sieve residues, lots I-101 and I-103, have provided numerous holoplanktonic molluscs (pteropods); the taxon-omy and biostratigraphical implications of these taxa are outlined in the present paper. Five species are described as new: Altaspiratella tavianii sp. nov., Limacina aryanaensis sp. nov., L. perforata sp. nov., L. yazdii sp. nov. and Texacuvierina hodgkinsoni sp. nov. On the basis of these data, the Soh samples most probably are of latest Ypresian or earliest Lutetian age. In terms of pteropod zonation, the pre-sent assemblage may be considered to belong to the earliest part of Pteropod Zone (PZ) 10, the boundary between PZ 9 and 10 having been recently redefined by the LAD of Camptoceratops priscus. The crinoids will be described in detail in a forthcoming paper. KEY WORDS: Iran, Eocene, holoplanktonic molluscs, Thecosomata, biostratigraphy, correlation, new taxa Introduction Early and middle Eocene (Ypresian-Lutetian) clays, marls and limestone/marl intercalations are widely exposed in the Soh area, north of Isfahan (north-central Iran). At two lo-calities within the Sarakeh Syncline two temporary trenches have been dug for the extraction of samples for micro- and macrofossil analyses. The co-ordinates of Trench-1, the Villa section, are 33 26 54 N, 51 26 26 E (elevation: 2377 metres); those of the main trench (Trench-2, the Estakhr section) are 33 26 48 N, 51 26 48 E (eleva-tion: 2381 metres). From both trenches, eight samples each, weighing roughly 20 kilogrammes, have been recov-ered. Two further samples from the Estakhr section, I-101 and I-103, taken from an unnamed formation, equivalent to the Jahrom Formation in the Zagros Basin (W-SW Iran) (La-combe et al., 2006), from respectively 18 and 20 metres above the base of the section, which corresponds to the Paleocene-Eocene boundary, have yielded pteropods and

an array of bourgueticrinid crinoids (cups, radices and col-umnals). In the two sieve residues, lots I-101 (lower sam-ple) and I-103 (upper sample), numerous holoplanktonic molluscs (pteropods) have been recognised. Members of two families, the Limacinidae and Praecuvierinidae, have been identified, with nine species in five genera, as de-scribed below. On the basis of these data, the Soh samples most probably are of latest Ypresian or earliest Lutetian age, postdating the last appearance datum (LAD) of Camp-toceratops priscus (Godwin-Austen, 1882) and predating the first occurrence of Limacina pygmaea (Lamarck, 1805) and Limacina asiatica Janssen, in Janssen et al., 2011. In terms of pteropod zonations (indicated as PZ), the present assemblage may be considered to belong to the earliest part of PZ 10, the boundary between PZ 9 and 10 having been recently redefined by the LAD of Camptoceratops priscus (see Janssen et al., 2011, p. 90). The crinoids will be de-scribed in detail in a forthcoming paper (Jagt & Donovan, in prep.). We thank Chris King (Bridport, UK) for com-menting on an earlier version of the manuscript.

- 24 -

Geological setting The Soh area is situated some 100 km northwest of Isfa-han, in north-central Iran (Fig. 1).

Figure 1. Map of the Soh area, north of Isfahan (north-central Iran). In addition to widely distributed Palaeozoic and Mesozoic strata (Zahedi, 1973; Weddige, 1984; Mannani & Yazdi, 2009) in the area, reddish clastic terrestrial (c. 300 metres in thickness) rocks of Paleocene age crop out. These are overlain by marine, nearshore clastic Eocene rocks (total thickness near 1,200 metres), which yield rich assemblages of benthic foraminifera, bivalves, gastropods, nautiloid cephalopods and serpulids (Figs 3, 4). The Paleocene-Eocene boundary is exposed over large distances in the Soh area; two trenches have been dug for the excavation of samples close to this. The first, the Villa section, and the second, the Estakhr section, both yielded eight samples each, each weighing around 20 kilogrammes. The first level sampled is close to the Paleocene-Eocene boundary and yielded charophytes and quite some decapod crusta-cean remains, mostly cheliped fragments. Samples from 10 metres above the boundary furnished near 90 per cent of benthic foraminifera such as Operculina and Elphidium, while two further (some 60 kilogrammes) from 18 and 20 metres above it produced crinoids, gastropods (inclusive of

pteropods) and scaphopods. All these samples were taken from an as yet unnamed formation, equivalent to the Jahrom Formation in the Zagros Basin (W-SW Iran) (La-combe et al., 2006). Overlying the Eocene rocks are the Lower Red, Qom and Upper Red formations of Oligocene to Pleistocene age. Basic material Sample I-103 yielded a quantity of molluscan taxa as well as some non-molluscs, such as scleractinian corals. Mol-luscs include abundant pteropods and a large number of small benthic bivalve, gastropod and scaphopod species, representing numerous species. These are not considered further here. Sample I-101, a washing residue of 63 grammes, yielded numerous pteropods in the > 0.5 mm fraction, and a few benthic molluscan taxa. Only juvenile individuals of the commonest pteropod species were re-covered from the < 0.5 mm residue, only a small portion of which was studied. This sample also contains many fora-minifera (mainly benthic species, just a few globigerinids), some small echinoderm spines and a few ostracods. All unsorted and unidentified benthic molluscs, now in the collections of the Naturalis Biodiversity Center (Leiden; abbreviation: RGM), in three lots (bivalves, scaphopods, gastropods), are available for further study. In both sam-ples, molluscs are preserved as limonitic internal moulds and, especially the benthics, frequently also as pseudo-morphs that retain details of ornament. Numerous (in sam-ple I-101 even most specimens) are pressure distorted, and all are, at least partially covered by a matrix crust which hides morphological details. The crust appeared to be un-solvable in formic acid, but could for the greater part be removed by 10-15 minutes 42 kHz (± 10%) ultrasonic treatment; specimens remained intact. Systematic palaeontology (A.W. Janssen) Phylum Mollusca Linnaeus, 1758 Class Gastropoda Cuvier, 1797 Clade Thecosomata de Blainville, 1824 Superfamily Limacinoidea Gray, 1847 Family Limacinidae Gray, 1847 Genus Altaspiratella Korobkov, 1966 (= Plotophysops Curry, 1982) Type species – ‘Limacina elongatoides’ (Aldrich) (by original designation) = Physa elongatoidea Aldrich, 1887 (Eocene, Ypresian). Type species of Plotophysops is P. bearnensis Curry, 1982 (same age). Altaspiratella gracilens Hodgkinson in Hodgkinson, Garvie & Bé, 1992 Figure 5

* 1992 Altaspiratella gracilens Hodgkinson, new spe-cies, Hodgkinson in Hodgkinson, Garvie & Bé, p. 14, pl. 1, figs 4, 5.

- 25 -

Figure 2. Lithostratigraphical column of the Estakhr-section, with description of the sampled beds (Sarakeh Syncline). Description – High-conical shell, approximately 2.7 times higher than wide, of c. four rather convex whorls separated by a deep suture. Apical and apertural parts are missing, but apparently the aperture is relatively small and situated obliquely with respect to the shell's long axis. An umbili-cus is absent. Material examined – Estakhr section, sample I-101, RGM 777 000/1 fragment; sample I-103, RGM 777 007/1 (Fig. 5), RGM 777 008/7. Discussion – To date, four species have been considered to belong to the genus Altaspiratella, viz. A. bearnensis (Curry, 1982), A. elongatoidea (Aldrich, 1887), A. gra-cilens and A. multispira (Curry, 1982). They are all charac-terised by a high-conical shell and absence of an umbilicus. Altaspiratella multispira is much more slender than the

present species, whereas A. bearnensis and A. elongatoidea approach it more closely. Still there are clear differences: in both A. bearnensis and A. elongatoidea the apical angle is wider, the whorls increase more rapidly in diameter and height, with a more superficial suture, resulting in a much larger aperture. These species were all originally recorded from Ypresian rocks. Altaspiratella gracilens, in fact based on rather poorly preserved specimens, agrees better with the Iranian material, although it cannot be substantiated that both have the same apertural reinforcements (in A. gracilens the apertural lip is widened). Still, based on the original illustrations, the present material best matches that taxon. Altaspiratella gracilens was first described from the Weches Formation (Texas, USA) and the Cane River For-mation (Louisiana, USA); the species is of late Ypresian to Lutetian age (NP 13-15; Hodgkinson et al, p. 10, fig. 3).

- 26 -

Figure 3. Outcrops in the Soh area. 1, 2 and 6. Marly beds with benthic foraminifera and crinoids; 3. Basal Eocene bed with charophytes and decapod crustacean remains; 4. Thin-bedded, sandy limestone at 10 metres above the base of the section; 5. Paleo-cene reddish clastic beds, comprising mostly conglomerates and terrestrial red clays; 7. Base of Eocene marly beds in the Villa sec-tion; the yellow arrow marks the beds with serpulid worms (Rotularia); 8. The Paleocene-Eocene boundary in the Estakhr section; the yellow arrow marks the crab-rich beds. Altaspiratella tavianii sp. nov. Figures 6, 7 Diagnosis – Extremely elongate species of Altaspiratella, when complete approximately six times higher than wide. Initial whorl naticoid; subsequent whorls very high, sepa-rated by markedly oblique sutures. No umbilicus. Description – Extremely slender shell, (reconstructed) six times taller than wide, with more than five whorls. Apical

shell parts with protoconch (Fig. 6) are preserved in two specimens (holotype H = 1.75 mm, W = 0.53 mm). The initial whorl is naticoid, while subsequent whorls increase rapidly in height, the body whorl is even up to four times higher than wide, separated by a distinct and very oblique suture. Apertural parts are incomplete, but what remains shows a relatively small aperture, pointed above, rounded abapically and obliquely positioned with respect to the shell’s vertical axis. There is no umbilicus.

- 27 -

Figure 4.1. Angular unconformity between late early Cretaceous (Albian) and post-Miocene clastic and travertine beds; 2. Eocene se-quence in the Sarakeh syncline; the black arrow marks post-Eocene (Oligocene-Miocene) strata of the Qom Formation; 3. Carbonates of middle Eocene (Lutetian) age with macrofaunas; 4. The Estakhr section in the Sarakeh Syncline; the black arrow marks clastic beds within the Eocene sequence. Etymology – The species is named after Dr Marco Taviani (Istituto di Scienze Marine, Sezione di Geologia Marina, C.N.R., Bologna, Italy), who frequently supported my pteropod studies. Type material – Sample I-101: holotype, Fig. 6a, b, RGM 777 001 (H = 1.75 mm, W = 0.53 mm), paratypes RGM 777 002/5; sample I-103, paratypes RGM 777 009/1 (Fig. 7a, b), RGM 777 010/6.

Type locality – Estakhr section, sample I-101; Soh area, north-central Iran, 33° 26' 48” N, 51° 26’ 48” E, elevation c. 2381 m, unnamed formation, equivalent to the Jahrom Formation in the Zagros Basin (W-SW Iran), 18 m above the Paleocene-Eocene boundary; estimated age latest Ypre-sian/earliest Lutetian (see below). Discussion – The present new species has a very unusual shape, nothing similar has ever been published. Its elongate

- 28 -

shell form, however, fits quite well in the genus Altaspi-ratella, in which it, together with the species A. bearnensis, A. elongatoidea, A. gracilens and A. multispira (in that order) represents a series of species with increasing slen-derness and despiralisation. It has been put forward (Jans-sen in Cahuzac & Janssen, 2010, pp. 51, 52; Janssen & Peijnenburg, in press, fig. 8) that these species together suggest a development in which the spire of the shell be-comes increasingly more uncoiled, making the impression as if this is an evolutionary sequence, leading from Lima-cinoidea-Limacinidae to Cavolinioidea-Creseidae. The present new species seems to acknowledge that notion, which, however, is contradicted by the fact that the creseid species which most closely resembles it, Camptoceratops priscus (Godwin-Austen, 1882) appeared already during the Ypresian, which is clearly earlier than the age assign-ment of the present assemblage indicates.

Figure 5. Altaspiratella gracilens Hodgkinson in Hodgkinson, Garvie & Bé, 1992; sample I-103; RGM 777 007; a: apertural, b: lateral view. However, on the basis of DNA sequencing a closer rela-tionship than hitherto assumed has recently been suggested between two Recent species of the families Creseidae and Limacinidae (Jennings et al., 2010), which led Bouchet (2013) in the WoRMS website to include the Creseidae in the superfamily Limacinoidea. Contrarily, Corse et al. (2013, p. 14, tab. 3) surprisingly consider Altaspiratella to be the first occurring Pseudo-thecosomata, but without any discussion or statement sub-stantiating their point of view. In our opinion neither the structures of aperture and columella, nor the morphology of the suture show any relationship to pseudothecosomes, whereas the above outlined transitional range of limacinids to creseids seems to support Jennings’ results on the basis of molecular work. I therefore maintain the genus Altaspi-ratella confidently in the Limacinidae. Genus Currylimacina Janssen, 2003 Type species – Skaptotion cossmanni Curry, 1982, by original designation (Eocene, Ypresian). Currylimacina cossmanni (Curry, 1982) Figure 8

Figures 6-7. Altaspiratella tavianii sp. nov., sample I-101; 6a, b, holotype, RGM 777 001; sample I-103; 7a, b, paratype RGM 777 009, specimen slightly compressed; a: apertural, b: lateral views.

* 1982 Skaptotion cossmanni Curry, p. 39. pl. 1, fig. 8a-c.

. 1992 Skaptotion ? reklawensis Garvie, new species, Garvie in Hodgkinson et al., p. 23, pl. 7, figs 1-4.

. 2003 ‘Skaptotion’ cossmanni Curry, 1982: Janssen, p. 166.

v. 2010 Currylimacina cossmanni (Curry, 1982) – Jans-sen in Cahuzac & Janssen, p. 28, pl. 4, figs 1-7; pl. 5, figs 1-3.

Description – Limacinid of nautiloid shape, earlier whorls are completely hidden in an apical ‘umbilicus’ and in the few Iranian specimens covered with matrix and invisible. Only the body whorl is visible and has a spherical shape, with the upper and lower apertural margins protruding above and beyond the penultimate whorl. The real umbili-cus is narrow and deep, but also covered with matrix. In one of the specimens the actual shell is present in a limoni-tised state showing the characteristic micro-ornament of collabral striations. Material examined – Sample I-103, RGM 777 011/1 (Fig. 8a, b), RGM 777 012/2. Discussion – This species was first described from the Ypresian of Gan (southwest France); it also occurs in coe-val rocks in the North Sea Basin (Janssen in Cahuzac & Janssen, 2010, p. 29) and, as ‘Skaptotion? reklawensis’, in the Reklaw and Weches formations in the USA (late Ypre-sian-early Lutetian, NP13-15; Hodgkinson et al., p. 8, fig. 1).

Figure 8. Currylimacina cossmanni (Curry, 1982); sample I-103; RGM 777 011: a: apertural, b: apical views.

- 29 -

Genus Heliconoides d’Orbigny, 1835 Type species – Heliconoides inflata (d’Orbigny, 1834), by subsequent designation of Adams & Adams (1858) (Re-cent). Heliconoides mercinensis (Watelet & Lefèvre, 1885) Figure 9

* 1885 Spirialis mercinensis Watelet & Lefèvre, p. 102, pl. 5, fig. 2a-c.

v. 2007 Heliconoides mercinensis (Watelet & Lefèvre) - Janssen et al., p. 163, figs 7-8 (with extensive synonymy).

v. 2010 Heliconoides mercinensis (Watelet & Lefèvre, 1885) – Janssen, p. 165, fig. 2.

v. 2011 Heliconoides mercinensis (Watelet & Lefèvre, 1885) – Janssen et al., p. 76, figs 13-16.

Description – Shell sinistral, planorboid, with approxi-mately 3! rounded whorls in a regular spiral. Initial whorl hardly or not protruding, apical plane slightly concave to very slightly raised (Fig. 7b). Aperture rounded in frontal view, upper margin at the same height or only very slightly lower than penultimate whorl. The basal part of the aper-ture is lowered beyond the base of the foregoing whorl. Apertural margin with a rounded v-shaped incision (lateral view), internally thickened, but these structures are not preserved in the present specimens. Umbilicus wide and shallow. Material examined – Sample I-101, RGM 777 003/1395: sample I-103, RGM 777 014/many in small concretion, RGM 777 015/755, RGM 777 013/1 (Fig. 9a-d). Discussion – This species, the oldest pteropod hitherto recognised, is known from rocks of latest Paleocene (Tus-cahoma Sand Formation, Bear Creek Marls of Alabama, USA; Janssen, 2010) and early Ypresian age of the North Sea Basin (extremely common in concretions from the London Clay, United Kingdom, and in similar ‘cement-stones’ from the earliest Eocene Fur Formation, Mo Clay, in Denmark; Pteropod Zone 6), but it is present at intervals during pteropod zones 6 to 9, the latter one situated near the boundary between Ypresian and Lutetian (e.g., it is absent in the well-known Ypresian locality of Gan, south-west France, Pteropod Zone 9, NP12-13; Cahuzac & Jans-sen, 2010). Originally the species was introduced from the ‘Cuisian’ (= Ypresian) of the Paris Basin. It was also found to be common in parts of the Ypresian of Rotterdam, the Netherlands (Janssen, 2010), co-occurring with the creseid Camptoceratops priscus, and also in the Lillebælt Forma-tion of Denmark (Janssen et al., 2007), dated as early Lu-tetian on the basis of dinoflagellates. In the latter assem-blage C. priscus was absent, but another limacinid (Heli-conoides lillebaeltensis Janssen in Janssen et al., 2007) unknown from any other locality, was abundantly present. This species was also common in samples from Tashkura, Uzbekistan (Janssen et al., 2011), dated as Ypresian (NP 13-14), where it co-occurred with several other pteropod species absent in the present assemblage, such as e.g.

Camptoceratops priscus and Euchilotheca elegans Harris, 1894.

Figure 9. Heliconoides mercinensis (Watelet & Lefèvre, 1885); sample I-103; RGM 777 013; a: apical, b: apertural, c: umbilical, d: lateral views. Genus Limacina Bosc, 1817 Type species – 'le Clio hélicine’ = Limacina helicina (Phipps, 1774), by monotypy (Recent). Limacina aryanaensis sp. nov. Figures 10, 11 Diagnosis – Relatively large (H to almost 3! mm) species of Limacina, slightly higher than wide to about as wide as high. Five whorls slightly angular below mid-height, gradually increasing in diameter. Base rounded, narrowly umbilicated. Description – Conical limacinid, the largest specimens (H = 3.4, W = 3.0 mm) slightly higher than wide, more juve-nile shells are approximately as high as wide (holotype, Fig. 10a-d). There are up to five convex whorls which regularly increase in diameter. The whorls are rather con-vex with a slightly angular periphery situated below mid-height, under which the next whorl attaches. The aperture is lunate, situated obliquely with respect to the shell’s ver-tical axis. As far as can be observed the columella is straight or slightly curved. A very narrow umbilicus pre-sumably is present, but covered with matrix in all speci-mens Etymology – The new species is named after the Islamic Republic of Iran. The name of Iran is the modern Persian derivative from the Proto-Iranian term Ary"n", meaning ‘Land of the Aryans’ (http://en.wikipedia.org/wiki/Iran; consulted July 2011). Type material – Sample I-103, holotype RGM 777 016 (Fig. 10a-d); paratypes RGM 777 017/1 (Fig. 11), RGM

- 30 -

777 018/9. Type locality – Estakhr section, sample I-103; Soh area, north-central Iran, 33° 26’ 48” N, 51° 26’ 48” E, elevation c. 2381 m, unnamed formation, equivalent to the Jahrom Formation in the Zagros Basin (W-SW Iran), 20 m above the Paleocene-Eocene boundary; estimated age latest Ypre-sian/earliest Lutetian (see below). Discussion – A number of Eocene limacinids with elevated spire resemble the present specimens superficially. None of these, however, demonstrates the faint peripheral angular-ity of the whorls. Limacina voluta Hodgkinson in Hodg-kinson et al. (1992, p. 21, pl. 4, fig. 9), from Eocene rocks in offshore boreholes off eastern Canada, remains smaller (H = 1.8 mm) and has a distinctly more acute apex. Lima-cina smithvillensis Hodgkinson in Hodgkinson et al. (1992, p. 19, pl. 3, fig. 16), from the middle Lutetian of Texas (USA), has a shell height of only 1.5 mm but at that size already 5 whorls and a more oval shell shape. Heliconoides nemoris (Curry, 1965, p. 362, fig. 17a-b), from the Barto-nian of the Hampshire Basin (United Kingdom), as well as Limacina guersi Janssen (2010, p. 168, figs 7 and 8) from the Ypresian of Rotterdam (The Netherlands), remain both smaller, have planispiral inital whorls and their whorls are relatively lower and gradually rounded. Finally, Heliconoi-des lillebaeltensis Janssen in Janssen et al. (2007, p. 161, figs. 3-8, 12-13) has a more globose shell of five whorls and a distinctly lower apical part. As it cannot be decided on the basis of the present internal moulds if this species originally had apertural reinforce-ment structures it is included in the genus Limacina. Limacina perforata sp. nov. Figure 12 Diagnosis – Limacina up to just over 2.4 mm high and 3.3 mm wide, the whorls forming a very low spire. Body whorl large, occupying 9/10th of shell height. Number of whorls 3! to 3# gradually increasing. Aperture large, lunate, only slightly less high than the body whorl. Columella with abaxial curvature. Umbilicus wide, c. one fifth of shell diameter. Description –A relatively large limacinid (holotype H = 2.42, W = 3.30 mm, some damaged specimens reach slightly larger dimensions), about 1.3-1.4 times wider than high, with 3!-3# whorls gradually increasing in diameter and forming an only very slightly elevated cone. The body whorl is large, occupying almost the entire shell height. Aperture lunate, 1.3 times higher than wide, columella with an abaxial curvature below base of penultimate whorl, ap-ertural margin apparently simple. Base gradually rounded, with a deep and relatively wide umbilicus of c. one fifth of the shell diameter, in several specimens (holotype, Fig. 10a) with a faint ridge bordering the shell’s basal plane. Etymology – The new species is ‘perforate’ with reference to the wide and deep umbilicus. Type material – Sample I-103, holotype RGM 777 019

(Fig. 12a-d); paratypes RGM 777 020/28.

Figures 10-11. Limacina aryanaensis sp. nov., sample I-103; 10a-d, holotype, RGM 777 016, a: apical, b: apertural, c: umbili-cal, d: lateral views; 11, paratype, RGM 777 017, apertural view. Type locality – Estakhr section, sample I-103; Soh area, north-central Iran, 33° 26’ 48” N, 51° 26’ 48” E, elevation c. 2381 m, unnamed formation, equivalent to the Jahrom Formation in the Zagros Basin (W-SW Iran), 20 m above the Paleocene-Eocene boundary; estimated age latest Ypre-sian/earliest Lutetian (see below). Discussion – This new species resembles Limacina weche-sensis Hodgkinson in Hodgkinson et al. (1992, p. 21, pl. 5, figs. 1-6; middle Lutetian, Weches Formation, NP 15, of Texas, USA) closely in shell shape, but differs in a few important respects. First of all fully grown L. wechesensis of 3! whorls reaches a shell height of only 0.8 mm, whereas L. perforata attains more than three times that size, having the same number of volutions. Also in L. wechesensis some specimens have a completely flat apical plane, but in the Iranian specimens the whorls are always at least slightly showing in a frontal view. The columella of L. wechesensis is described as ‘straight and essentially par-allel to the shell axis’, whereas it shows an abaxial curva-ture in the Iranian material. Finally the American species has a narrower umbilicus (‘1/7 to 1/6 of shell diameter’, compared to c. 1/5th in L. perforata.

- 31 -

Figure 12. Limacina perforata sp. nov., sample I-103; holo-type, RGM 777 019; a: apical, b: apertural, c: umbilical, d: lateral views. Limacina yazdii sp. nov. Figures 13, 14 Diagnosis – Limacina with carinated whorls, typically wider than high to rarely almost as high as wide. Whorls very slightly convex, carina situated just above the abapical suture. Base only slightly convex with a very narrow um-bilicus. Description – Low conical limacinid of 3$ slightly convex whorls with a distinct, rounded carina located just above the suture. The shell is wider than high (holotype H = 1.35, W = 1.77 mm, apical angle 112°, Fig. 13), the whorls in-crease gradually in height and especially in width, resulting in a relatively large, rounded-squarish aperture. The base of the shell is only slightly convex and has a very narrow umbilicus, visible in few specimens only. As holotype one of the better, but not completely adult specimens is chosen. Most paratypes are more or less strongly deformed by rock pressure. One of the larger paratypes (H = 2.10, W = 2.20 mm; Fig. 14) is relatively higher, with an apical angle of c. 90°). Etymology – The species is named after Dr Mehdi Yazdi, Department of Geology, Faculty of Science, Isfahan Uni-versity, Isfahan, Iran (http://sci.ui.ac.ir/geology/Yazdi. htm), who collected the present material. Type material – Sample I-101: paratypes RGM 777 004/5; sample I-103: holotype, RGM 777 021 (Fig. 13a-d), para-types RGM 777 022/1 (Fig. 14), RGM 777 023/20 (several of the paratypes are either juvenile or severely distorted by rock pressure). Type locality – Estakhr section, sample I-103, Soh area, north-central Iran, 33° 26’ 48” N, 51° 26’ 48” E, elevation c. 2381 m, unnamed formation, equivalent to the Jahrom Formation in the Zagros Basin (W-SW Iran), 20 m above

the Paleocene-Eocene boundary; estimated age latest Ypre-sian/earliest Lutetian (see below). Discussion – Two species from the New World, introduced in Hodgkinson et al. (1992) are comparable to Limacina yazdii, viz. L. aegis Hodgkinson, from presumably early Eocene rocks (collected from downhole contamination in Cretaceous levels) in boreholes off E Canada, and L. heli-kos Hodgkinson, from the early Eocene (early Ypresian) Wilcox Formation in Louisiana (USA). The former is a small species (H = 0.8 mm) with almost completely flat whorls, its first 1! whorls planispiral, a more accentuated carina and an apical angle of 133°. Limacina helicos, on the other hand, reaches a shell height of 1.3 mm and has 5# very flat whorls, the first two of which are planispiral, and very superficial sutures. Its apical angle of 63° is con-siderably smaller than in L. yazdii. Limacinidae sp. indet. Figure 15 Description – Small, conical limacinid of c. four whorls, approximately as tall as wide. Only one of the few avail-able specimens is not distorted during diagenesis (H = 0.85, W = 0.83 mm; Fig. 15), but its initial whorl is miss-ing. The tangents along the whorls are convex, the base of the body whorl is slightly flattened. A small umbilicus is covered with matrix. Apertural structures are not pre-served.

Figures 13-14. Limacina yazdii sp. nov., sample I-103; 13a-d, holotype, RGM 777 021, a: apical, b: apertural, c: umbilical, d: lateral views; 14, paratype, RGM 777 022, apertural view.

- 32 -

Material examined – Sample I-101, RGM 777 005/4; sam-ple I-103, RGM 777 024/1 (Fig. 15a, b), RGM 777 025/4. Discussion – The only well-preserved specimen resembles in size and shape a pteropod described from the Ypresian (NP 13) of Tashkura (Uzbekistan; Janssen et al., 2011, fig. 17), indicated as Heliconoides aff. paula (Curry, 1982). The present specimen, although superficially similar, dif-fers even more from the real H. paula from Gan (southwest France) than the Uzbekistan specimens: its middle whorls are lower, the tangents are clearly convex, and its base is slightly flattened. Also nothing is known about possible apertural reinforcements. In these circumstances I prefer to include the present specimens in open nomenclature. It could very well be that Iranian and Uzbekistan specimens represent two different species, or that both fall within the range of variability of H. paula. Better preserved speci-mens are needed for a decision.

Figure 15. Limacinidae sp. indet., RGM 777 024, sample I-103; a: apertural, b: lateral views. Superfamily Cavolinioidea Gray, 1850 Family Praecuvierinidae Janssen, 2006 Genus Texacuvierina Janssen, 2005 Type species – Cuvierina gutta Hodgkinson in Hodgkinson et al., 1992, by original designation (Eocene). Texacuvierina hodgkinsoni sp. nov. Fig. 16

. 1992 Cuvierina lura Hodgkinson, new species, Hodgkinson in Hodgkinson et al., p. 32, pl. 11, figs. 12, 13 (non Hodgkinson; non figs 11, 14, 15 = Praecuvierina lura).

Description – Praecuvierinid species of almost cylindrical shape. Practically all available specimens are flattened dur-ing diagenesis, but the illustrated specimen (H = 1.96, W = 0.87 mm) seems to be rather undamaged. Its greatest width is situated in the lower half of the shell and in lateral view it is somewhat inflated on its presumably ventral side. The aperture is circular and situated obliquely (higher dorsally) with respect to the shell’s long axis. Apical shell parts are missing, a septum is not preserved. Etymology – It is an honour to name this new taxon after

Kenneth A. Hodgkinson, who was the first to describe and illustrate it and who also supplied profuse information on North American Eocene pteropods. Type material – Sample I-101, paratypes RGM 777 006/5. Sample I-103, holotype (Fig. 16a, b), RGM 777 026; para-types RGM 777 027/15. Type locality – Estakhr section, sample I-103, Soh area, north-central Iran, 33° 26’ 48” N, 51° 26’ 48” E, elevation c. 2381 m, unnamed formation, equivalent to the Jahrom Formation in the Zagros Basin (W-SW Iran), 20 m above the Paleocene-Eocene boundary; estimated age latest Ypre-sian/earliest Lutetian (see below). Discussion – With the name of Cuvierina lura Hodgkinson (in Hodgkinson et al.,1992) described two different ptero-pod types, that he considered to possibly represent two separate species. The holotype (Hodgkinson et al., 1992, pl. 11, fig. 11) is a strongly inflated form that was desig-nated type species of the genus Praecuvierina by Janssen, 2005, whereas other specimens from the same locality are much less strongly inflated, with far more parallel sides, basically agreeing with ‘Cuvierina’ gutta, the type species of Texacuvierina Janssen, 2005. This form resembles a number of specimens in the Iranian material for a great deal. The American specimens have a shell height of no more than 1.14 mm, whereas the Iranian ones reach a height of almost 2 mm, but, as far as can be judged from the few illustrations, they resemble the American ones closely otherwise. As the strongly inflated form is not pres-ent in my material I take that as an indication that the original description indeed includes two species. The American specimens are from the Weches Formation (Texas), dated as Lutetian (NP 15), which seems to be a bit younger than the present material. Biostratigraphical notes An age assignment for the present assemblage of nine spe-cies, of which five are new and one is indeterminate, encounters problems, as the stratigraphical distribution of just three or four species is known. By far the commonest of these, Heliconoides mercinensis, is long ranging, occur-ring, with barren intervals, from the latest Paleocene to the early Lutetian (NP 9-15).

Figure 16. Texacuvierina hodgkinsoni sp. nov., sample I-103, holotype RGM 777 026; a: ventral, b: left lateral views.

- 33 -

The second species, Currylimacina cossmanni, is known from Ypresian (NP 12-13) and Lutetian (NP 15). Altaspi-ratella gracilens ranges from late Ypresian to Lutetian (NP 13-15). Finally, the American specimens here included in the new taxon Texacuvierina hodgkinsoni are dated as Lu-tetian, NP 15. Two ‘nearby’ Eocene assemblages (Janssen et al., 2011) from Uzbekistan (Tashkura, samples U404-405) were dated as Ypresian (NP 13) and yielded, apart from Heli-conoides mercinensis, also Camptoceratops priscus and Euchilotheca elegans Harris, 1894, both absent in the Ira-nian samples. Overlying levels from Uzbekistan, dated as late Ypresian/early Lutetian ( NP zone 14-15) yield only H. mercinensis in the lower part of NP 14 (sample U406), in which also the characteristic Lutetian species Limacina pygmaea (Lamarck, 1805) appears for the first time. This later species, however, is not found in the Iran samples. Considering these data is seems most probable that the present assemblage has an age of latest Ypresian or earliest Lutetian (younger than the LOD of Camptoceratops and predating the first occurrence of Limacina pygmaea and Limacina asiatica Janssen, in Janssen et al., 2011, which might agree with an early part of zone NP 14. The absence of Euchilotheca elegans, in Uzbekistan abundantly occur-ring below as well as above the Ypresian/Lutetian bound-ary, remains curious. The vertical range of Texacuvierina hodgkinsoni (Lutetian, NP 15) contradicts this age assign-ment. It might be that the American specimens represent yet another taxon or the T. hodgkinsoni range may be longer than currently known. In terms of pteropod zonation (Janssen & King, 1988) the Iranian assemblage may be considered to belong to the earliest part of PZ 10, as the boundary between PZ 9 and 10 was recently redefined by the LOD of Camptoceratops priscus (Janssen et al., 2011). As the two samples available for the present study origi-nate from a very restricted stratigraphical interval it would be useful to study pteropods from a considerably longer section, covering larger parts of Ypresian and Lutetian rocks to substantiate the above age assignment. References Adams, A. & A.Adams, 1858. The genera of recent Mollusca 2.

London (J. van Voorst): 1-68. Aldrich, T.H. 1887. Notes on Tertiary fossils, with descriptions of

new species. The Journal of the Cincinnati Society of Natural History 10(2): 78-83.

Blainville, [H.M.D.] de. 1824. Mollusques, Mollusca (Malacoz.). Dictionnaire des Sciences naturelles 32: 1-392.

Bosc, [L.A.G.] 1817. Limacine. Nouveau Dictionnaire d’Histoire naturelle 18: 42.

Bouchet, P. 2013. Limacinoidea. Accessed through: World Register of Marine Species (WoRMS) at http://www.marine-species.org/aphia.php?p=taxdetails&id=411902, accessed on 2013-02-23.

Cahuzac, B. & Janssen, A.W. 2011. Eocene to Miocene holoplanktonic Mollusca (Gastropoda) of the Aquitaine Basin, southwest France. Scripta Geologica 141: 1-193.

Corse, E., Rampal, J., Cuoc, C., Pech, N., Perez, Y. & Gilles, A. 2013. Phylogenetic analysis of Thecosomata Blainville, 1824 (Holoplanktonic Opisthobranchia) using morphological and

molecular data. PLoS ONE 8(4): e59439. doi:10.1371/journal.pone.0059439 Curry, D., 1965. The English Palaeogene pteropods. Proceedings

of the Malacological Society of London 36: 357-371. Curry, D. 1982. Ptéropodes éocènes de la tuilerie de Gan

(Pyrénées-Atlantiques) et de quelques autres localités du SW de la France. Cahiers de Micropaléontologie 4 (1981): 35-44.

Cuvier, G.[L.C.F.D.] 1797. Tableau élémentaire de l’histoire naturelle des animaux. Paris (Baudouin): i-xvi, 1-710.

Godwin-Austen, H.H. 1882. On a fossil species of Camptoceras, a freshwater mollusk from the Eocene of Sheerness-on-Sea. Quarterly Journal of the Geological Society of London 38: 218-221.

Gray, J.E. 1847. A list of the genera of recent Mollusca, their synonyma and types. Proceedings of the Zoological Society of London 15: 129-219.

Gray, J.E. 1850. Catalogue of the Mollusca in the collection of the British Museum 2. Pteropoda. London (British Museum/E. Newman): i-iv, 1-45.

Harris, G.F. 1894. On the discovery of a pteropod in British Eo-cene strata, with the description of a new species. Proceed-ings of the Malacological Society of London 1(2): 61-62.

Hodgkinson, K.A., Garvie, C.L. & Bé, A.W.H. 1992. Eocene euthecosomatous Pteropoda (Gastropoda) of the Gulf and eastern Coasts of North America. Bulletins of American Paleontology 103(341): 5-62.

Janssen, A.W. 2003. Notes on the systematics, morphology and biostratigraphy of fossil holoplanktonic Mollusca 13. Considerations on a subdivision of Thecosomata, with the emphasis on genus group classification of Limacinidae. Cainozoic Research 2: 163-170.

Janssen, A.W. 2005. Development of Cuvierinidae (Mollusca, Euthecosomata, Cavolinioidea) during the Cainozoic: a non-cladistic approach with a re-interpretation of Recent taxa. Basteria 69: 25-72.

Janssen, A.W. 2006. Notes on the systematics, morphology and biostratigraphy of fossil holoplanktonic Mollusca 16. Some additional notes and amendments on Cuvierinidae and on classification of Thecosomata (Mollusca, Euthecosomata). Basteria 70: 67-70.

Janssen, A.W. 2010. Pteropods (Mollusca, Euthecosomata) from the early Eocene of Rotterdam (the Netherlands). Scripta Geologica Special Issue 7: 161-175.

Janssen, A.W. & King, C. 1988. Planktonic molluscs (Pteropods). In: Vinken, R. et al. (eds). The northwest European Tertiary Basin. Results of the International Geological Correlation Programme Project no. 124. Geologisches Jahrbuch A100: 356-368.

Janssen, A.W., King, C. & Steurbaut, E. 2011. Notes on the systematics, morphology and biostratigraphy of fossil holoplanktonic Mollusca 21. Early and middle Eocene (Ypresian-Lutetian) holoplanktonic Mollusca (Gastropoda) from Uzbekistan. Basteria 75:71-93.

Janssen, A.W. & Peijnenburg, K.T.C.A. in press. Holoplanktonic Mollusca: development in the Mediterranean Basin during the last 30 Ma and their future. In: Goffredo, S. & Dubinsky, Z. (eds). The Mediterranean Sea: Its history and present challenges. Springer.

Janssen, A.W., Schnetler, K.I. & Heilmann-Clausen, C. 2007. Notes on the systematics, morphology and biostratigraphy of fossil holoplanktonic Mollusca 19. Pteropods (Gastropoda, Euthecosomata) from the Eocene Lillebælt Clay Formation (Denmark, Jylland). Basteria 71: 157-168.

Jennings, R.M., Bucklin, A., Ossenbrügger, H. & Hopcroft, R.R. 2010. Species diversity of planktonic gastropods (Pteropoda and Heteropoda) from six ocean regions based on DNA bar-code analysis. Deep Sea Research 2. Topical Studies in Oceanography 57: 2199-2210.

- 34 -

Korobkov, I.A. 1966. Krylonogie (Mollusca Pteropoda) paleo-genovykh otlozhenij juga S.S.S.R. Voprosy Paleontologii 5: 71-92.

Lacombe, O., Mouthereau, F., Kargar, S. & Meyer, B., 2006. Late Cenozoic and modern stress fields in the western Fars (Iran): implications for the tectonic and kinematic evolution of central Zagros. Tectonics, 25, TC1003, 27 pp., doi:10.1029/2005TC001831.

Linnaeus, C. 1758. Systema naturae per regna tria naturae, se-cundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis 1 (editio decima, reformata). Holmiae (Salvii): 1-824.

Mannani, M. & Yazdi, M. 2009. Late Triassic and early Creta-ceous sedimentary sequences of northern Isfahan Province (central Iran): stratigraphy and paleoenvironment. Boletín de la Sociedad Geológica Mexicana 62: 207-211.

Orbigny A. d’, 1834-1847. Voyage dans l’Amérique méridionale (le Brésil, la république orientale de l’Uruguay, la république Argentine, la Patagonie, la république du Chili, la république de Bolivia, la république du Pérou), exécuté pendant les années 1826, 1827, 1828, 1829, 1830, 1831, 1832 et 1833. Paris, Bertrand & Strasbourg, Levrault, 5: 1-48, 73-128, pls 1-2, 9-13, 15-16, 56, 1834; 49-72, 129-176, pls 3-8, 17-23, 25, 55, 1835; 177-184, pls 14, 24, 26-28, 30-32, 34-35, 37, 58, 1836; 185-376, pls 38-52, 57, 1837; pls. 54, 59-66, 68-69, 1839; 377-424, pls 53, 67, 70-71, 1840; 425-488, pls 72-76, 79-80, 1841; pls 83-85, 1842; 489-728, 1846; pls 78-79, 81-82, 1847 (xliii + 758 pp., 85 plates) (publication dates after Sherborn & Griffin (1934).

Phipps, C.J. 1774. A voyage towards the North Pole undertaken by his Majesty’s Command 1773. London (W. Bowyer & J. Nichols): i-viii, 1-253.

Watelet, A. & Lefèvre, T. 1885. Note sur des ptéropodes du genre Spirialis découverts dans le Bassin de Paris. Annales de la Société malacologique de Belgique 15 (for 1880): 100-103.

Weddige, K. 1984. Externally controlled late Paleozoic event of the Iran Plate. Neues Jahrbuch für Geologie und Paläontologie, Abhandlungen 168: 278-286.

Zahedi, M. 1973. !tude géologique de la région de Soh (W de Iran central). Tehran (Geological Survey of Iran): 1-197.