Lower Oligocene Bivalves of Ramanian Stage from Kachchh, Gujarat, India

Lower Oligocene bivalves of Ramanian Stage from Kachchh, Gujarat, India

R P Kachhara∗, R L Jodhawat and K Bigyapati Devi Department of Geology, M.L. Sukhadia University, Udaipur 313 001, India. ∗Corresponding author. e-mail: [email protected]

Marine Oligocene sequences in India outcrop only in western part of Kachchh. Earlier researchers have recognized the Oligocene strata under the Nari Series (Nagappa 1959; Chatterji and Mathur 1966). The Nari Series has a type area in Pakistan. It has two subdivisions – the Lower Nari (Lower Oligocene) and the Upper Nari (Upper Oligocene). It seems that there is no valid proof about the age of the Lower Nari due to lack of proper fauna (Eames 1975), and according to Pascoe (1962), the Upper Nari slightly transgress into Aquitanian (Lower Miocene), therefore, one has to be very cautious. Biswas and Raju (1971) reclassified the Oligocene strata of Kachchh and lithostratigraphically clubbed them as the Maniyara Fort Formation with type section along the Bermoti stream. This Formation has four members. The lower three members correspond to the Ramanian Stage (Lower Oligocene, Biswas 1971, 1973) while the uppermost to the Waiorian Stage (Upper Oligocene, Biswas 1965, 1971, 1973). The Ramanian Stage is characterized by large forams especially Nummulites fichteli, Nummulites fichteli intermedius, Lepidocyclina (Eulepidina) dialata and Operculina sp. Several ostracods are also known to occur. Megafauna include bivalves, gastropods, echinoids, corals, mammals and reptiles. Concerning bivalves earlier researchers have recorded a few taxa namely Trisidos semitorta (Lamarck), Cubitostrea angulata (J de C Sowerby), Pecten (Amussiopecten) labadyei d’Archiac and Haime, Periglypta puerpera (Linne’) var. aglaurae Brongniart, Ostrea fraasi Mayer Eymer and listed Pecten laevicostatus JdeC Sowerby, Callista pseudoumbonella Vredenburg and Clementia papyracea (Gray) from Kachchh as against overall 42 forms from the Nari Series as a whole (Vredenburg 1928). This tempted us to make an attempt to collect bivalve fauna systematically which are occurring prolifically in the Ramanian Stage. In the present work, for this purpose, sections are worked out around Lakhpat (23◦50N; 68◦47E), Maniyara Fort (23◦2805N; 68◦37E) Rakhdi Dam (23◦2726N; 68◦4010E) and Waior (23◦2505N; 68◦4137E) with a view to highlight the entombed bivalve taxa. Authors have encountered 53 species of which 23 are restricted to the Ramanian Stage.

1. Introduction Group, Argillaceous Group and Recent–Upper Tertiary. Of these, Nummulitic Group has been Wynne (1872) for the ﬁrst time reported Tertiary equated by the subsequent researchers with the deposits in Kachchh. He classiﬁed these deposits Nari Series of Pakistan and the term Nari has into six groups namely Sub-Nummulitic Group, been adopted for the Oligocene strata of Kachchh. Gypseous Shales, Nummulitic Group, Arenaceous Sen Gupta (1959, 1964) has considered Oligocene

Keywords. Bivalves; Ramanian Stage; Lower Oligocene.

J. Earth Syst. Sci. 121, No. 2, April 2012, pp. 405–438 c Indian Academy of Sciences 405 406 R P Kachhara et al beds of Lakhpat area as part of the Nari Series Mathur (1988) has reviewed the work on marine with characteristic Nummulites fichteli Michelotti Tertiary larger invertebrate fauna of India and in abundance. Biswas (1965) proposed a new reported occurrences of Oligocene molluscs in classification of Tertiary rocks of Kachchh and the Maniyara Fort Formation (Bermoti Series) grouped Oligocene beds into the Lakhpat Series, with a check list – Pecten laevicostatus, Cytherea characterized by reticulate Nummulites, well cor- (Callista) pseudoumbonella, Ostrea angulata, relatable with the Nari Series of Sind–Baluchistan. Cerithium sp., Lunatia sp. (Sen Gupta 1964), Tewari and Singh (1966) while working on Kanoj– Venus (Clementia) papyracea, Pecten labadyei, Sehe area of western Kachchh considered their Amusium sp., Trochus sp., Trochus cf. comulans, Bed Nos. 4 and 5 as Lattorfian (L. Oligocene) Natica sigaratina (Chatterji and Mathur 1966), and Rupelian (M. Oligocene) respectively, the and Ostrea angulata, Ostrea latimarginata, Ostrea latter one on the basis of the occurrence of sp., Pecten sp., Turritella sp., Cypraea sp.,? Lepidocyclina (Eulepidina) dialata. Raju (1969) Scalaria sp. (Raju 1974). Khosla and Pant (1988) has shown that in Ramania area of Kachchh have studied three sections in Kachchh (i) near the Oligocene strata start with appearance of the Rakhdi Dam, (ii) between the Waior Dam and Nummulites fichteli. In addition, Raju et al Waior village, and (iii) outside Lakhpat Fort. They (1970) have recognized three biozones, viz., Num- have recorded Oligocene ostracod assemblages mulites intermedius-fischteli assemblage zone, with two biozones one each in the Ramania and N. intermedius-fichteli-Lepidocyclina assemblage the Waior Stages of the Bermoti Series namely zone and Miogypsinoides complanata zone of Actinocytheries ramaniaensis and Actinocythereis Lower, Middle and Upper Oligocene, respectively kutchensis with an age of Lattorfian to Rupelian in Walasara and Goyela areas of Kachchh. They and Chattian, respectively. also favoured the view expressed by Chatterji Biswas (1992) has given more detailed account and Mathur (1966) that the Bed No. 2 of Tewari of Tertiary stratigraphy of Kachchh in which (1959) in Waior area containing Spiroclypus ran- he retained earlier proposed nomenclature for all janae which was assigned to Lower Miocene lithostratigraphic formations and the stage names should be taken as Chattian (Upper Oligocene) were rectified to proper ending. Following him, in the absence of typical Lower Miocene fossils. there are five biozones in the Maniyara Fort For- While writing a note, Biswas (1971) modified mation, viz., Nummulites fichteli zone of Lower his earlier proposed classification by chang- Oligocene in Basal Member, Nummulites fichteli- ing the nomenclature of the Lakhpat Series to Lepidocyclina (Eulepidina) dialata zone of Lower the Bermoti Series with two stages namely the Oligocene (Rupelian) in Coral Limestone Member Ramania (Lattorfian to Rupelian) and Waior and Planolinderina freudenthali zone, Miogypsina (Chattian). It may be recalled that the Waior (Miogypsinodes ) bermudezi zone, and Miogypsina Stage in his earlier classification was part of the (Miogypsinoides) complanata-formosensis zone in Khari Series assigned to Miocene. Later on, Biswas the ascending order of Upper Oligocene (Chattian) and Raju (1971) proposed a rock-stratigraphic in the Bermoti Member. Same scheme is being classification for Tertiary rocks of Kachchh in followed by Pandey and Dave (1998). It may be which Oligocene strata were included in the Mani- noted that the Nari Series were deposited during yara Fort Formation with four members namely Oligocene time and has been divided into Lower Basal, Lumpy Clay, Coral Limestone and Bermoti. and Upper. However, regarding the age of the Of these, first two are Lower Oligocene, third one Lower Nari, there is no fool proof evidence (Eames as Middle Oligocene and the last one as Upper 1951) and the Upper Nari seems to transgress Oligocene. Mohan and Pandey (1971) have also into Lower Miocene (Pascoe 1962). Only a few preferred to retain the name the Maniyara Fort molluscan fauna from Kachchh Oligocene strata Formation for the Oligocene beds of Kachchh. are reported by earlier researchers as compared to Raju (1974) on the other hand, favoured the overall 42 forms of the Nari Series. In view of it, a chronostratigraphy classification for the Oligocene systematic collection is being made from different strata of Kachchh as the Ramania and the Waior sections of the Maniyara Fort Formation, viz: Stages in the ascending order. He recognized two biozones in the Ramania Stage namely Nummulites • outside northern wall of the Lakhpat Fort, fichteli-intermedius zone and Nummulites fichteli- • the Rakhdi Dam, intermedius/Lepidocyclina (Eulepidina)zoneof • the Bermoti stream around Bermoti village, and Lower to Middle Oligocene (Lattorfian to • a section between Waior village and the Waior Rupelian), and on the basis of Miogypsinidae Dam of lower three members namely Basal, assemblage especially Miogypsina (Miogypsi- Lumpy Clay and Coral Limestone of Lattor- noides) complanata Schlumberger, assigned the fian to Rupelian time, i.e., Lower to Middle Waior Stage to Upper Oligocene (Chattian). Oligocene. Lower Oligocene bivalves of Ramanian Stage 407

2. Stratigraphy among bivalves Pectinids and Oysters are quite conspicuous as also foraminifers. Middle part is Oligocene strata of Kachchh indicated earlier are solely characterized by corals and in the upper grouped lithostratigraphically under the Maniyara part molluscs again made their appearance but Fort Formation divisible into four members namely with very thin population. The Bermoti stream Basal, Lumpy Clay, Coral Limestone and Bermoti. has a full section of the Ramanian Stage. The Leaving aside the last one, others chronostrati- succession starts with brownish to yellowish glau- graphically equated to the Ramanian Stage of conitic siltstone followed by calcareous claystone, Lattorfian to Rupelian time. Assignment of age is highly fossiliferous cement coloured claystone and based on the presence of reticulate Nummulites dirty white coral limestone with peculiar weather- namely Nummulites fichteli and Lepidocyclina ing at the top. At the Rakhdi Dam, lithic units (Eulepidina) dialata. It may be mentioned that are in the form of glauconitic sandstone, shale, hard otherwise also Nummulites do not occur beyond limestone, marly limestone and yellow shales Middle Oligocene time. Strata of the Ramanian sequentially in the assending order. At the Waior Stage outcrop at several localities, however, bet- Dam, succession consists of ash grey shales, white ter sections are around Lakhpat Fort (23◦500N; limestone, brownish yellow limestone and yellow- 68◦470E), the Bermoti stream (23◦2747N; 68◦ ish white limestone. These litho units are of Basal, 3615E), the Rakhdi Dam (23◦2853N; 68◦40 Lumpy Clay and Coral Limestone Members of the 58E), and the Waior Dam (23◦2540N; 68◦42 Maniyara Fort Formations equated to the Rama- 04E) and all are studied (figure 1). In Lakhpat nian Stage. Main bulk of fauna is from strata of area, the Ramanian Stage is represented by dirty Lumpy Clay Member followed by Coral Limestone white to brown limestone with little sand content. Member. Following Biswas (1992), the molluscs Lower part of this is mainly fossiliferous, and yielding beds are Bed Nos. 38, 40, 44, 44A and 44B.

Figure 1. Geological map of a part of the Tertiary rocks of southwestern Kachchh, India. 408 R P Kachhara et al Miocene Waior Bermoti Rakhdi Locality )–––R–– )–––R–– )) – R – – R R R R – – Oligocene–Miocene Lower Miocene ) R – – – – Lower Oligocene (Linne’) R – – R – Miocene–Recent )) R R – – R – R – – – Lower Miocene Lower Miocene n.sp. ) – – – R – L. Oligocene ) – – – R – Lower Miocene ) sp. R – – – – – )R––––U.Palaeocene– )–––R–– Reeve ) – – R – – Lower Miocene ) R – – – – Miocene–Recent sp. nov. ) sp. – – – R – – JdeCSowerby (J de C Sowerby) R – – – – L. Eocene–L. Oligocene (Linne’) R – – – – Miocene–Recent n.sp. n.sp. folium Jain Mayer )––RR–– ) – – – R – Miocene Dey ) Geloina ( Fuchs d’Archiac and Haime d’Archiac Plicatula Darteplicatula Darteplicatula Chlamys Argopecten Aequipecten Aequipecten Spondylus Spondylus Vredenburg Lutraria ( ( ( ( ( ( ( Glossus Cytherocardia ( ( JdeCSowerby ( ( ( Amussiopecten Amussiopecten Ostrea Ostrea (Nagao and Otatume) Lopha ( ( ( ( ( phillipinarum takoi cytheroides ramanianense labadyei placenta lingua kachchhensis soomrowensis feddeni quilonensis bhatiyaensis rouaulti bermotiensis maniyaragarhensis cf. Polymesoda Lutraria Arctica planata Glossus Glossus Lopha Chlamys Ostrea Plicatula Pecten Pecten Chlamys Chlamys Chlamys Hyotissa hyotis Spodylus Ostrea Spodylus Plicatula Plicatula Check list and locality wise distribution of bivalves in Kachchh. Table 1. 17 18 19 20 15 16 1 14 7 5 6 4 3 2 Sl. no Species name Lakhpat Waior Dam Stream Dam Geological range 12 11 13 10 8 9 Lower Oligocene bivalves of Ramanian Stage 409 – W R R R Miocene–Pliocene R – – – – Lower Oligocene Vredenburg R W – R R Oligocene – L. Miocene ) – W – R – Oligocene )) – – W W – – R R – – L. Miocene L. Miocene ) – W – R R Oligocene n.sp. R W – R – — Jodhawat prototranquebaricus ) – W R R R Oligocene Vredenburg Koenen – W – R – Oligocene )) R W R R – Miocene–Pliocene ) – W – R – Miocene ) – W – R – Miocene–Pliocene ) – W – R – Miocene (Linne’) – W – R R Oligocene–Miocene (Linne’) R W R R R Oligocene (Noetling) Vredenburg Vredenburg ) sp. – W – R – globosa (Lamarck) – W – R – Oligocene pseudoumbonella ) sp. R – – – R — ) R W R – R Oligocene–Pliocene ) ) R– –––UpperEocene Vredenburg s.–W–R–– )sp. Trachycardium Trachycardium Trachycardium lakhpatensis protoimbricata Vredenburg Brongniart ( ( ( Nemocardium Discors JdeCSowerby ) ) ( ( porrecta (Noetling) Vredenburg s.–W–R–– )sp. ) Cotter Vredenburg (JdeCSowerby) Poromya Aequipecten Aequipecten Chlamys ( Gmelin Callista Callista Callista ( ( ( Fragum Arcopaginula Callistotapes Callistotapes ( ( ( ( Ostrea Ostrea ( ( ( ( ( Pitar Pitar granosa aglaurae paucicostata ( ( pseudoumbonella pseudoliratus bhagothorense inﬂata sindiense naricum var. minbuense protosubrugosum var. prototranquebaricus Vredenburg var. var. virgatus yawensis Paphia Paphia Callista Pitar Fragum Nemocardium Nemocardium Tellina Trachycardium Periglypta puerpera Pitar Ostrea Periglypta puerpera Chlamys Chlamys Trachycardium Trachycardium Poromya Chlamys Callista Trisidos semitorta Ostrea Callista R = Ramanian Stage; W = Waiorian Stage. 34 35 33 32 28 29 30 31 27 42 43 26 41 25 24 39 40 36 23 21 37 38 22 410 R P Kachhara et al

3. Systematics and description of species ranges is as Chlamys (Chlamys) multistriata Deshayes (Eocene), Anomia (Anomia) bhatti n.sp. In all 511 individuals of bivalves have been pro- (M. Eocene–Oligocene), Gryphaeostrea brongniart cured from the strata of the Ramanian Stage of (Bronn) (Palaeocene–Miocene), Cubitostrea angu- Lakhpat, the Bermoti stream, the Rakhdi Dam and lata (J de C Sowerby) (Eocene–Miocene), Crassostrea the Waior Dam. These have been studied system- avadichi n.sp. (M. Eocene–Oligocene), Cubitostrea atically representing two subclasses Pteriomorpha perplicata (Dall) (M. Eocene), Diplodonta (Diplo- and Heterodonta; three orders – Arcoida, Pterioida donta) incerta d’Archiac (Oligocene), Chama and Veneroida; 10 superfamilies – Arcacea, Pectin- (Chama) brimonti d’Archiac and Haime (Eocene), acea, Ostreacea, Cardiacea, Mactracea, Tellinacea, Pitar (Calpitaria) carteri (d’Archiac and Haime) Arcticacea, Glossacea, Corbiculacea, Veneracea; and Clementia (Clementia) papyracea (Grey) and 13 families – Arcidae, Pectinidae, Plicatu- (Eocene–Miocene). Systematics of these species is lidae, Spondylidae, Gryphaeidae, Ostreidae, Cardi- discussed elsewhere, hence, not included in the idae, Mactridae, Tellinidae, Arcticidae, Glossidae, table. All others are listed in table 1 with their loc- Corbiculidae and Veneridae with 53 taxa. Of these ality, horizon and known geological range. Out of 23 taxa are restricted to the Ramanian Stage, 20 these 43 taxa, six are indeterminate forms (for bre- ranging higher up into the Waiorian Stage. Ten spe- vity of paper not described). All the measurements cies are long ranging coming from lower horizons are in millimeters and ﬁgures in parenthesis show of Eocene time. Their check-list with geological ratios with respect to length on percentage basis.

Class: Bivalvia Linné, 1758 Subclass: Pteriomorphia Beurlen, 1944 Order: Arcoida Stoliczka, 1871 Superfamily: Arcacea Lamarck, 1809 Family: Arcidae Lamarck, 1809 Subfamily: Arcinae Lamarck, 1809 Genus: Trisidos Röding, 1798 Type species: Arca tortuosa Linné, OD. Recent; Philippines

Trisidos semitorta (Lamarck)

Figure 2. Trisidos semitorta (Lamarck) W1/20. (a) Exterior of left valve and (b) dorsal view (×1). Bar scale = 10 mm.

1901 Arca (Parallelipipedum) semitorta Lamarck, Noetling, p. 151. 1928 Arca semitorta Lamarck; Vredenburg, p. 417. 1982 Trisidos semitorta (Lamarck), Kanno, p. 57, pl. XIV, figures 5–6. 1997 Trisidos semitorta (Lamarck), Jain, p. 46, pl. IX, figures 19–21. 2004 Trisidos semitorta (Lamarck), Lyngdoh, p. 32, pl. II, figure 2. Material: 17 specimens (all are internal mould). Horizon and locality: Ramanian Stage; the Bermoti stream, Maniyara Fort, and Lakhpat Fort. Waiorian Stage; Waior Village. Lower Oligocene bivalves of Ramanian Stage 411

Dimensions (mm):

Sp. no. Length Height Inﬂation

R2U/79 36.60 18.50 (50.50) 19.00 (51.90) W1/20 40.20 22.70 (56.46) 19.20 (47.76)

Remarks: Example recorded here are very typ- no doubt in their identity as Trisidos semitorta ical representatives particularly the specimen no. (Lamarck). The species is recorded only from W1/20 matching perfectly with the Sp. no. 58/22 Oligocene beds of India, Pakistan, Myanmar and from Kathiawar recorded by Jain (1997), leaves Philippines.

Order: Pterioida Newell, 1965 Suborder: Pteriina Newell, 1965 Superfamily: Pectinacea Rafinesque, 1815 Family: Pectinidae Rafinesque, 1815 Genus: Chlamys Röding, 1798 Type species: Pecten islandicus Müller, 1776; SD Herramannsen, 1847, Recent; North Atlantic Subgenus: Chlamys s.str.

Chlamys (Chlamys) bhatiyaensis Jain MS

Figure 3. Chlamys (Chlamys) bhatiyaensis Jain R1/18. Exterior of right valve (×1.5). Bar scale = 10 mm.

1997 Chlamys (Chlamys) bhatiyaensis Jain, p. 60, pl. X, ﬁgures 17–21. Material: One specimen (original shell). Horizon and locality: Ramanian Stage; the Bermoti stream, Maniyara Fort. Dimensions (mm):

Umbonal No. of Sp. no. Length Height Inﬂation angle ribs ◦ R1/18 28.00 31.40 (112.14) 07.00 (25.00) 85 24

Remarks: The shell is subtrigonal in outline, slightly narrow interspaces; these features are compressed, slightly higher than long, with straight enough to assign the lone individual recorded here antero-dorsal and postero-dorsal margins, subtend- to the species Chlamys (Chlamys) bhatiyaensis ing an apical angle of about 85◦, evenly curved Jain. Moreover, it resembles very well with the anterior, posterior and ventral margins, unequal type material particularly with sp. no. 24/883 from auricles, surface sculpture of 24 radial ribs with Lower Miocene strata of Kathiawar. 412 R P Kachhara et al

Subgenus: Aequipecten Fischer, 1886 Type species: Ostrea opercularis Linne’, 1758; M. Recent; France

Chlamys (Aequipecten) feddeni Vredenburg

Figure 4. Chlamys (Aquipecten) feddeni Vredenburg L4/908. Exterior of right valve (×1). Bar scale = 10 mm.

1928 Pecten (Chlamys) feddeni Vredenburg, p. 433, pl. XXV, ﬁgures 1–4, 6. 1997 Chlamys (Aequipecten) feddeni Vredenburg var. kurangaensis Jain, p. 64, pl. XI, ﬁgures 9–10. Material: 31 specimens (all are original shell). Horizon and locality: Ramanian Stage; the Bermoti stream, Maniyara Fort, and Lakhpat Fort. Dimensions (mm):

Umbonal No. of Sp. no. Length Height Inﬂation angle ribs ◦ R2U/122 37.30 36.40 (97.58) 9.5 (25.46) 108 23

Remarks: This is one of the most commonly with the GSI type no. 13373 in all respects, hence, occurring species and our material is conspeciﬁc the assignment.

Chlamys (Aequipecten) quilonensis Dey 1961 Chlamys (Aequipecten) quilonensis Dey, p. 43, pl. II, ﬁgures 8–9. Material: One specimen (internal molud). Horizon and locality: Ramanian Stage; Lakhpat Fort. Dimensions (mm):

No. of Sp. no. Length Height Inﬂation ribs

L4/13 32.14 31.18 (97.00) 12.00 (37.33) 17

Remarks: The solitary right valve is slightly ill- the GSI type nos. 16419–20. Thus its merger preserved but tallying very well in shape, height/ with Chlamys (Acquipecten) quilonensis Dey is length ratio, nature and number of ribs (17) to unquestionable. Lower Oligocene bivalves of Ramanian Stage 413

Chlamys (Aequipecten) prototranquebaricus Vredenburg

Figure 5. Chlamys (Aequipecten) prototranquebaricus Vredenburg L4/86. Exterior of right valve (×1.2). Figure 6. Chlamys (Aequipecten) prototranquebaricus Vredenburg L4/2. Exterior of right valve (×2). Figure 7. Chlamys (Aequipecten) prototranquebaricus Vredenburg L4/43. (a) Exterior of right valve and (b) interior of right valve (×1). Bar scale = 10 mm.

1928 Pecten (Aequipecten) prototranquebaricus Vredenburg, p. 433, pl. XXV, ﬁgures 7–12, 14. 1997 Chlamys (Aequipecten) prototranquebaricus Vredenburg, Jain, p. 63, pl. XI, ﬁgures 3–8. Material: 47 specimens (all are original shell). Horizon and locality: Ramanian Stage; the Bermoti stream, Maniyara Fort, and Lakhpat Fort. Waiorian Stage; Waior Village. Dimensions (mm):

Umbonal No. of Sp. no. Length Height Inﬂation angle ribs ◦ L4/2 15.68 15.92 (101.53) 05.00 (31.88) 90 18 ◦ L4/86 25.00 25.60 (102.40) 08.00 (32.00) 82 15

Remarks: The material recorded here of the Vredenburg (1928) under the name Pecten present collection is in full agreement with (Aequipecten) prototranquenbaricus Vredenburg, the type specimen from Kachchh recorded by thus the assignment.

Chlamys (Aequipecten) prototranquebaricus var. paucicostata Vredenburg

Figure 8. Chlamys (Aequipecten) prototranquebaricus var. paucicostata Vredenburg R3/12. Interior of right valve (×2.5). Bar scale = 10 mm.

1928 Pecten (Chlamys) prototranquebaricus var. paucicostata Vredenburg, p. 433, pl. XXV, ﬁgure 14. 414 R P Kachhara et al

Material: Six specimens (all are original shell). Horizon and locality: Ramanian Stage; the Bermoti stream, Maniyara Fort, the Rakhdi Dam. Waiorian Stage; Waior Village. Dimensions (mm):

Umbonal No. of Sp. no. Length Height Inﬂation angle ribs ◦ R3/12 12.80 14.00 (109.37) 05.60 (43.75) 81 14

Remarks: With respect to preceding species, typical species as Pecten (Chlamys) prototranque- the variety recorded here has less number of baricus var. paucicostata Vredenburg. Further, our rounded ribs, i.e., 14–15 instead of 18–20, with specimens are compared with GSI type no. 13383 narrow interspaces are enough to isolate from the to which these are found to agree well.

Subgenus: Argopecten Monterosato, 1899 Type species: Pecten solidulus Reeve, 1853; OD. Recent; location unknown

Chlamys (Argopecten) soomrowensis J de C Sowerby

Figure 9. Chlamys (Argopecten) soomrowensis J de C Sowerby R2U/8. Exterior of left valve (×3). Bar scale = 10 mm.

1840 Pecten soomrowensis J de C Sowerby, pl. XXV, figure 14. 1901 Pecten kokenianus Noetling, p. 117, pl. IV, figures 2–6. 1928 Pecten (Chlamys) senatoria (Gmelin) var. soomrowensis J de C Sowerby; Vredenburg, p. 434. 1997 Chlamys (Argopecten) soomrowensis J de C Sowerby; Jain, p. 74, pl. XII, figures 11–14, pl. XIII, figures 1–2. Material: Two specimens (both are original shell). Horizon and locality: Ramanian Stage; Bermoti stream, Maniyara Fort. Dimensions (mm):

Umbonal No. of Sp. no. Length Height Inﬂation angle ribs ◦ R2U/8 10.40 13.00 (125.00) 04.00 (38.46) 71 33

Remarks: The individuals recorded here are from Myanmar under the name Chlamys comparatively small, however, on direct compari- (Argopecten) soomrowensis (J de C Sowerby) these son with the type material (GSI type no. 7500-2) are observed to be conspeciﬁc. Lower Oligocene bivalves of Ramanian Stage 415

Genus: Pecten M¨uller, 1776 Type species: Ostrea maxima Linn´e, 1758; SD. Schmidt, 1818. Recent; England Subgenus: Amussiopecten Sacco, 1897 Type species: Pecten burdigalensis Lamarck, 1809; OD. Miocene; France

Pecten (Amussiopecten) labadyei d’Archiac and Haime

Figure 10. Pecten (Ammusiopecten) labadyei d’Archiac and Haime R1/12. Exterior of right valve (×0.5). Bar scale = 10 mm.

1928 Pecten (Amussiopecten) labadyei d’Archiac and Haime; Vredenburg, p. 430. Material: Nine specimens (all are original shell). Horizon and locality: Ramanian Stage; the Bermoti stream, Maniyara Fort, and the Waior Dam. Dimensions (mm):

Umbonal No. of Sp. no. Length Height Inﬂation angle ribs ◦ R1/12 47.50 43.50 (91.57) 12.00 (25.26) 74 20

Remarks: The present Kachchh collection has Further, these are compared with the type mate- the typical representatives of the species, viz., Pecten rial (Sp. no. 13499) in GSI, Kolkata, and are found (Amussiopecten) labadyei d’Archiac and Haime. to be conspeciﬁc.

Pecten (Amussiopecten) placenta Fuchs

Figure 11. Pecten (Ammusiopecten) placenta R2U/112. Exterior of left valve (×0.3). Bar scale = 10 mm. 416 R P Kachhara et al

1879 Pecten placenta Fuchs, p. 105, pl. II, ﬁgures 3–4. 1928 Pecten (Amussiopecten) placenta Fuchs, Vredenburg, p. 432. 1997 Pecten (Amussiopecten) placenta Fuchs, Jain, p. 78, pl. XIII, ﬁgures 3–5. Material: Ten specimens (all are original shell). Horizon and locality: Ramanian Stage; the Bermoti stream, Maniyara Fort, and Lakhpat Fort. Waiorian Stage; Waior Village. Dimensions (mm):

Umbonal No. of Sp. no. Length Height Inﬂation angle ribs ◦ R2U/112 42.90 42.40 (98.83) 11.90 (27.73) 74 18

Remarks: The examples in hand, on direct (Amussiopecten) placenta Fuchs, thus, there is no comparison, are matching very well to the GSI hesitation in their assignment. type no. 13500, described under the name Pecten

Family: Plicatulidae Watson, 1930 Genus: Plicatula Lamarck, 1801 Type species: Spondylus plicatus Linn´e, 1758; SD. Schmidt, 1818. M. Triassic–Recent; Europe–Africa, N. America–Indonesia Subgenus: Plicatula s.str.

Plicatula (Plicatula) kachchhensis n.sp.

Figure 12. Plicatula (Plicatula) kachchhensis n.sp. R2U/36. Exterior of left valve (×3). Bar scale = 10 mm.

Material: One specimen (original shell). Horizon and locality: Ramanian Stage; the Bermoti stream, Maniyara Fort. Dimensions (mm):

Sp. no. Length Height Inﬂation

R2U/36 09.30 12.10 (130.10) 02.50 (26.88)

Description: Shell small, subequilateral, sub- straight, antero-dorsal small and appreciably con- ovate, narrow towards dorsal, subequivalve, right cave, postero-dorsal rectilinear, steeply inclined valve more convex in umbonal region, and slightly and extended to mid height; ventral, posterior and larger than the ﬂat left valve. Height is exceeding anterior margins are regularly curved making a the length, dorsal margin very short and almost semicircle with length as diameter at about mid Lower Oligocene bivalves of Ramanian Stage 417 height. Right valve has a large attachment area at Remarks: Its very small size, subovate outline, umbo, cardinal area very small, valve margins cre- few and very strong radials with hollow tubercles nulated; leaving aside the umbonal region, valve sur- diﬀerentiate this species from all other Tertiary face is ornamented by equally spaced strong radial forms belonging to genus Plicatula. ribs with hollow tubercles. Inter spaces bear secon- Etymology: The species name is derived from dary riblets, which are crossed over by co-marginal the place of occurrence, i.e., Kachchh (a district of growth rugae, auricles wanting. Interior not exposed. Gujarat State).

Subgenus: Darteplicatula Freneix and Gorodisk, 1963 Type species: Plicatula polymorpha Bellardi, 1854; OD. Eocene; Nigeria

Plicatula (Darteplicatula) bermotiensis n.sp.

Figure 13. Plicatula (Darteplicatula) bermotiensis n.sp. R2U/107. (a) Exterior of right valve and (b) interior of left valve (×1). Figure 14. Plicatula (Darteplicatula) bermotiensis n.sp. R2U/180. (a) Exterior of left valve and (b) dorsal view (×1). Bar scale = 10 mm.

Material: 12 specimens (all are original shell). Horizon and locality: Ramanian Stage; the Bermoti stream, Maniyara Fort. Dimensions (mm):

Sp. no. Length Height Inﬂation

R2U/107 34.80 32.00 (91.95) 12.50 (35.91) R2U/80 29.70 30.70 (103.36) 13.30 (44.78) R2U/78 32.30 31.20 (96.59) 13.50 (41.79) R2U/180 29.50 31.00 (105.08) 10.00 (33.89) R2U/175 34.50 33.00 (95.65) 14.60 (42.30) R2U/89 29.40 30.60 (104.08) 18.20 (61.90)

Description: Shell medium sized, suborbicu- Anterior and posterior margins are very broadly lar in outline, narrow towards dorsal, and height convex and merge with undulated ventral mar- about 9/10 to almost equal of the length. Shell gin uninterruptedly. Auricles are small; anterior surface is undulated, inﬂation moderate, attain- one slightly larger and distinctly separated. Sur- ing its maximum along the ventral margin. Dorsal face ornamentation consists of four radial folds margin is short, straight, hardly about a centimeter becoming very wide towards the ventral. Each in length. Antero-dorsal margin is almost straight fold marked by radial striation. This radial com- to very feebly concave, extending upto 1/3 of the ponent is crossed over by the concentric rugae, height, on the other hand, postero-dorsal one is which are becoming prominent towards the ventral perfect rectilinear, moderately inclined outwardly region. Mid-ventral has a sulcus between the two and extending from umbo to almost mid-height. plicae in the left valve and opposite to it in the 418 R P Kachhara et al right valve. Interspaces bear secondary riblets with from other known Tertiary forms. In nature of pri- hollow tubercles quite distinct in the mid-region. mary ornamentation it is more nearer to the geno- Ornamentation pattern varies, i.e., umbonal region type Plicatula (Darteplicatula) polymorpha Bellardi is characterized by small granules, and towards from Eocene of Nigeria, which can be diﬀerenti- ventral replaced by the concentric rugae which ated by its sub-oval outline, height in much excess is becoming prominent consequently radial com- of length, and in absence of distinct secondary ponent is almost obliterated. Interior is not sculpture. known. Etymology: The species is named after the Remarks: The suborbicular outline and pattern place of occurrence, i.e., Bermoti village of district of ornamentation, distinguish the recorded species Kachchh in Gujarat State.

Plicatula (Darteplicatula) maniyaragarhensis n.sp.

Figure 15. Plicatula (Darteplicatula) maniyaragarhensis n.sp. R2U/109. (a) Exterior of right valve, (b) exterior of left valve, and (c) dorsal view (×1.3). Bar scale = 10 mm.

Material: 14 specimens (all are original shell). Horizon and locality: Ramanian Stage; the Bermoti stream, Maniyara Fort. Dimensions (mm):

Sp. no. Length Height Inﬂation

R2U/114 20.60 18.60 (90.29) 08.70 (42.23) R2U/109 33.00 28.60 (86.66) 11.70 (35.45) R2U/58 25.20 24.50 (97.22) 05.70 (22.61) R2U/76 30.70 31.00 (100.97) 11.80 (38.43)

Description: Shell compressed, suborbicular, height, then suddenly and rapidly becoming much height almost equal to 9/10 of the length. Inﬂation wider. So, the interspaces are narrow in the lower increases to ventral, attaining its maximum at the half. These radial costae, six in number bear lower margin. Shell small to medium size and appears tubercles at regular interval, interspaces appear to be produced slightly towards anterior giving a to bear radial riblets with minor tubercles. The perception of being an oblique shell. Leaving aside radial component is crossed over by concentric auricular region the outline is almost orbicular. rugae which overlap the radials in the ventral Auricular dorsal margin is straight hardly about a half. Inter-spaces towards ventral becoming deeper centimeter in length. Umbo depressed, ill deﬁned, to form sulci bordered by plicae. Interior is not small and submedium. Shell surface is ornamented known. with six primary slightly curved radial costae, Remarks: It is almost similar to the preceding spe- which are regularly increasing in width upto mid cies namely Plicatula (Dartepicatula) bermotiensis Lower Oligocene bivalves of Ramanian Stage 419 n.sp., except for more number of radial costae, Etymology: The species is named after the i.e., six instead of four and in bearing tubercles at place of occurrence, i.e., Maniyaragarh (=Maniyara regular interval over the costae. Fort) of district Kachchh in Gujarat State.

Family: Spondylidae Gray, 1826 Genus: Spondylus Linn´e, 1758 Type species: Spondylus gaederopus Linn´e, 1758; SD. Schmidt, 1818. Recent; Mediterranean Subgenus: Spondylus s.str.

Spondylus (Spondylus) rouaulti d’Archiac

Figure 16. Spondylus (Spondylus) rouaulti d’Archiac L4/135. Exterior of right valve (×1). Bar scale = 10 mm.

1850 Spondylus rouaulti d’Archiac, p. 272. 1854 Spondylus rouaulti d’Archiac, d’Archiac and Haime, p.171, pl. XXIV, figures 6–8. 1927 Spondylus alexandrae Vredenburg, Cossmann and Pissarro, p.11, pl. II, figures 11–13. 1951 Spondylus alexandrae Vredenburg, Eames, p. 352. 1997 Spondylus alexandrae Vredenburg, Jain, p. 80, pl. XIII, figures 13–16.

Material: One specimen (original shell). Horizon and locality: Ramanian Stage; Lakhpat Fort. Dimensions (mm):

Sp. no. Length Height Inﬂation

L4/135 45.25 43.50 (96.13) 18.00 (39.77)

Remarks: Lone example from Lakhpat resem- (GSI type no. 10983), in all respects including over- bles fairly well to the representative of Spondylus all conﬁguration, general proportions, details of alexandrae Vredenburg, recorded by Cossmann external ornamentation, so there is hardly any need and Pissarro from Ranikot Beds of Pakistan to qualify its identity further. 420 R P Kachhara et al

Suborder: Ostreina Ferussac, 1822 Superfamily: Ostreacea Raﬁgnesque, 1815 Family: Gryphaeidae Vyalov, 1936 Subfamily: Pycnodonteinae Stenzel, 1959 Genus: Hyotissa Stenzel, 1971 Type species: Mytilus hyotis Linn´e, 1758; OD. Recent; Madagascar

Hyotissa hyotis (Linn´e)

Figure 17. Hyotissa hyotis (Linne’) L4/148. (a) Exterior of right valve and (b) exterior of left valve (×0.8). Bar scale = 10 mm.

1927 Ostrea hyotis Linné, Cox, p. 35, pl. III, figure 1. 1930 Ostrea hyotis Linné, Cox, p. 109, pl. XIII, figures 20–22. 1961 Ostrea hyotis Linné, Dey, p. 45. 1997 Hyotissa hyotis (Linné), Jain, p. 85, pl. XIV, figures 6–10. Material: Eight specimens (all are original shell). Horizon and locality: Ramanian Stage; Lakhpat Fort. Dimensions (mm):

Sp. no. Length Height Inﬂation L4/148 57.70 53.74 (93.13) 18.60 (32.23)

Remarks: It is a long ranging species, i.e., there. The individuals from Lakhpat are very well Miocene to Recent. Its attachment area, plicate tallying to the Kathiawar example (No. 38/100) commissure and distorted valve surface bearing recorded by Jain (1997) in every respect, therefore, crude, irregularly placed strong radial plicate ribs the identity is unquestionable. in umbonal region and have hyote spines here and

Family: Ostreidae Rafinesque, 1815 Genus: Ostrea Linné, 1758 Type species: Ostrea edulis Linné, 1758; SD. ICZN, Recent; England Subgenus: Ostrea s.str. Lower Oligocene bivalves of Ramanian Stage 421

Ostrea (Ostrea) lingua J de C Sowerby

Figure 18. Ostrea (Ostrea) lingua J de C Sowerby R2U/118. (a) Exterior of left valve and (b) interior of left valve (×0.7). Bar scale = 10 mm.

1840 Ostrea lingua J de C Sowerby, pl. XXV, ﬁgure 20. 1928 Ostrea lingua J de C Sowerby, Vredenburg, p. 428. 1997 Ostrea lingua J de C Sowerby, Jain, p. 93, pl. XVI, ﬁgures 7–10.

Material: Two specimens (both are original shell). Horizon and locality: Ramanian Stage; the Bermoti stream, Maniyara Fort. Dimensions (mm):

Sp. no. Length Height Inﬂation R2U/118 42.50 45.00 (105.88) 27.20 (64.00)

Remarks: In overall shape, length–height ratio, to Jain’s materials (especially sp. no. 55/610) in nature of ribbing, these recorded specimens are shape, ligament area and muscle scar rather than closely allied to the species Ostrea (Ostrea) lingua type one in GSI (No. 13947) which is very large J de C Sowerby. Moreover, these are matching well and narrow.

Ostrea (Ostrea) protoimbricata Vredenburg

Figure 19. Ostrea (Ostrea) protoimbricata Vredenburg R2U/124. (a) Exterior of left valve and (b) exterior of right valve (×1.2). Bar scale = 10 mm. 422 R P Kachhara et al

1928 Ostrea (Ostrea) protoimbricata Vredenburg, p. 425, pl. XXIII, ﬁgures 3–7. 1997 Ostrea (Ostrea) protoimbricata Vredenburg, Jain, p. 95, pl. XVII, ﬁgures 1–5.

Material: 36 specimen (all are original shell). Horizon and locality: Ramanian Stage; the Bermoti stream, Maniyara Fort, and Lakhpat Fort. Waiorian Stage; Waior Village. Dimensions (mm):

Sp. no. Length Height Inﬂation R2U/124 34.30 28.20 (82.20) 16.00 (46.64)

Remarks: It is also one of the most common material resembling very well to one or the other, species in Kachchh and its type material is housed therefore, conspeciﬁc to the species namely Ostrea in GSI, Kolkata (type no. 13370-2) to which our (Ostrea) protoimbricata Vredenburg.

Ostrea (Ostrea) lakhpatensis n.sp.

Figure 20. Ostrea (Ostrea) lakhpatensis n.sp. L4/83. (a) Exterior of right valve and (b) exterior of left valve (×1). Bar scale = 10 mm.

Material: One specimen (original shell). Horizon and locality: Ramanian Stage; Lakhpat Fort. Dimensions (mm):

Sp. no. Length Height Inﬂation L4/83 37.80 33.80 (89.41) 09.60 (25.39)

Description: Shell medium sized, oblique, sub- convex anterior margin covering up to 2/3 of rhomboidal, compressed, both valves equally thick, the height. Postero-dorsal margin short, slightly height about 9/10 of the length, subequilateral concave, meeting broadly convex ventral margin and slightly produced posteriorly. Right valve which is rising rapidly at antero-ventral corner almost flat, left valve slightly convex. Dorsal mar- to join the anterior margin. Umbo depressed ill gin gently convex about 2/3 of the length, merg- defined, median. Valve surface is ornamented by ing obtusely with steeply inclined, almost straight nine radial ribs which bifurcate almost at dorsal antero-dorsal which in turn meeting very broadly third and again at about the ventral third. Thus, Lower Oligocene bivalves of Ramanian Stage 423 increase in number of ribs towards ventral. Ribs are (a), figure 2, pl. XXIV (b), figure 1) a Miocene rounded, bear ill defined tubercles at interval and species from Baluchistan in respect of possession of separated by equal or narrow interspaces. Ribs as prominent depression to the anterior of the umbo, well as interspaces are crossed over by fine concen- otherwise, it is quite different being very small size tric rugae and an eminent growth halt slightly to and having bifurcating ribs. In nature of radial ribs, the inner side of the margins. Overall margins are it resembles Ostrea angulata J de C Sowerby (1840, crenulated except for dorsal one. Shell surface has pl. XXV, figure 17) which can be distinguished by a prominent depression at the postero-dorsal side its oblique subovate outline, hence, different. in the left valve and corresponding to it there is a Etymology: The species is named after the ridge in the right valve. Interior is not known. place of occurrence, i.e., Lakhpat village of district Remarks: It is approaching Ostrea pseudodigi- Kachchh in Gujarat State. talina Fuchs (Vredenburg 1928, p. 425, pl. XXIV

Ostrea (Ostrea) ramanianense sp. nov.

Figure 21. Ostrea (Ostrea) ramanianense sp. nov. R2U/92. (a) Exterior of left valve, (b) exterior of right valve, and (c) anterior view (×0.65). Bar scale = 10 mm.

Material: Seven specimens (all are original shell). Horizon and locality: Ramanian Stage; the Bermoti stream, Maniyara Fort. Dimensions (mm):

Sp. no. Length Height Inﬂation

R2U/92 57.40 54.50 (94.94) 31.50 (54.87) R2U/168 47.00 40.00 (85.10) 21.00 (44.68) R1/43 67.50 54.00 (80.00) 32.50 (48.14)

Description: Shell suborbicular to transversely postero-dorsal margin along with anterior- subelliptical with a slight tendency to become posterior ones are almost parallel and joining narrow towards dorsal margin, lower valve thick the asymmetrical, ventral margin in a regular much convex, dome like with maximum inﬂa- curve which is rising rapidly towards posterior. In tion in the central region. Attachment area is subelliptical forms posterior is slightly rostrate. prominent, almost circular and in the form of a Surface ornamented by sharp, distinct, thin, radial depression, about 2 cm in diameter. This area is costae, bearing tubercles at regular interval 4 in almost vertical to the remaining surface of the number with wide interspaces. Concentric orna- valve. In suborbicular form, height is slightly less mentation is in the form of irregular corrugation than the length. Concave antero-dorsal and convex becoming prominent towards ventral margin. 424 R P Kachhara et al

Along the hinge, umbo is raised, narrow, Remarks: At first instance, the holotype of the triangular, with distinct oblique resilifer bounded recorded species seems to exhibit good similarity by bourrelets. The upper valve is thin as an oper- with Ostrea khamirensis Cox (Jain 1997, p. 94, pl. culum and moderately convex in the umbonal XVI, figures 11–14) especially to sp. no. 47/124, in region, concave in central region and almost flat number of ribs and in much wide interspaces, car- near ventral. Umbo small ill defined, surface of rying tubercles at interval and to some extend in the valve bears few radial ribs traceable upto mid- overall configuration. However, on direct compari- height, then suddenly convert into broad shallow son with GSI type no. 17381 of Ostrea khamiren- folds. Margins crenulated. Interior is not known. sis Cox (1936, p. 35, pl. V, figures 2–4) that one Internally right valve below the umbo has a shal- is characterized by a triangular outline and has low, oblique resilifer with a distinct chomata on as many as 17 ribs, therefore, quite distinct. No both the sides. Valve also bears a muscle scar which other species is found to be closely related with the is very shallow and broadly elliptical, situated near recorded one in the literature cited, hence, a new the posterior margin, slightly dorsal to the mid- form. height. Commissural shelf is steeply inclined and Etymology: Specific name is derived from its well marked in the left valve. Interior of the right occurrence in the Ramanian Stage of Oligocene valve is not known. time.

Subfamily: Lophinae Vyalov, 1936 Genus: Lopha Röding, 1798 Type species: Mytilus cristagalli Linné 1758; SD. Dall, 1898. Recent; Indo–Pacific Subgenus: Lopha s.str.

Lopha (Lopha) folium (Linn´e)

Figure 22. Lopha (Lopha) folium (Linn´e) R2U/166. (a) Exterior of left valve and (b) exterior of right valve (×0.9). Bar scale = 10 mm.

1928 Ostrea folium Gmelin; Vredenburg, p. 429. 1971 Lopha (Lopha) folium (Linné), Stenzel in Moore, p. N1157–1158, figures J47 and J130. 1997 Lopha (Lopha) folium (Linné), Jain, p. 104, pl. XVIII, figures 8–13, pl. XIX, figures 1–4.

Material: Eight specimens (all are original shell). Horizon and locality: Ramanian Stage; the Bermoti stream, Maniyara Fort, and Lakhpat Fort. Lower Oligocene bivalves of Ramanian Stage 425

Dimensions (mm):

Sp. no. Length Height Inﬂation

R2U/166 48.20 43.80 (90.87) 17.50 (36.30)

Remarks: The species Lopha (Lopha) folium second stock and resembles to various ﬁgures cited (Linn´e) has two ecomorphs, one is attached to the in the synonymy and particularly to sp. no. 62/153 plant of gorganacean twigs and another attaches to from Kathiawar recorded by Jain (1997). There- sub-stratum. The example recorded here belongs to fore, the placement.

Subclass: Heterodonta Neumayr, 1884 Order: Veneroida H. Adams and Adams, 1856 Superfamily: Cardiacea Lamarck, 1809 Family: Cardiidae Lamarck, 1809 Subfamily: Trachycardiinae Stewart, 1930 Genus: Trachycardium M¨orch, 1853 Type species: Cardium isocardia Linn´e 1758; SD. von Martens, 1870. Recent; West Indies Subgenus: Trachycardium s.str.

Trachycardium (Trachycardium) sindiense Vredenburg

Figure 23. Trachycardium (Trachycardium) sindiense Vredenburg W1/55. (a) Exterior of left valve and (b) dorsal view (×1.5). Bar scale = 10 mm.

1928 Cardium (Trachycardium) sindiense Vredenburg, p. 446, pl. XXVII, ﬁgures 7, 9–10. 2004 Trachycardium (Trachycardium) sindiense Vredenburg, Lyngdoh, p. 79, pl. X, ﬁgure 10.

Material: 12 specimens (all are internal mould). Horizon and locality: Ramanian Stage; the Bermoti stream, Maniyara Fort, and Lakhpat Fort. Waiorian Stage; Waior Village. Dimensions (mm):

Sp. no. Length Height Inﬂation

W1/55 17.00 19.20 (112.94) 15.00 (88.23) 426 R P Kachhara et al

Remarks: As compared to GSI type no. 13406 ill-preserved but resembling very well in all details bearing the name Cardium (Trachycardium) sin- leaving no doubt about their identity. diense Vredenburg, our specimens are slightly

Trachycardium (Trachycardium) minbuense (Noetling)

Figure 24. Trachycardium (Trachycardium) minbuense (Noetling) W1/89. (a) Exterior of right valve and (b) dorsal view (×1.4). Bar scale = 10 mm.

1901 Cardium minbuense Noetling, p. 181, pl. X, figures 12–13. 1939 Cardium (Trachycardium) minbuense Noetling, Mukerjee, p. 16, pl. I, figure 9, pl. II, figure 5. 2004 Trachycardium minbuense (Noetling), Lyngdoh, p. 77, pl. X, figures 1–7.

Material: 12 specimens (all are internal mould). Horizon and locality: Ramanian Stage; the Bermoti stream, Maniyara Fort, and Lakhpat Fort. Waiorian Stage; Waior Village. Dimensions (mm):

Sp. no. Length Height Inﬂation No. of ribs W1/89 23.80 23.00 (96.63) 17.60 (73.94) 32

Remarks: On visit to GSI, Kolkata, the type specimens are tallying well to the ﬁgures cited in material related to Cardium minbuense Noetling, the synonymy, particularly to the ﬁgures 2 and 5 on was not available. However, on the other hand, pl. X, given by Lyngdoh (2004), hence, the identity.

Trachycardium (Trachycardium) protosubrugosum (Noetling)

Figure 25. Trachycardium (Trachycardium) protosubrugosum (Noetling) R2U/38. Exterior of left valve (×1.8). Bar scale = 10 mm. Lower Oligocene bivalves of Ramanian Stage 427

1901 Cardium protosubrugosum Noetling, p. 179, pl. X, ﬁgures 10–11. 1939 Cardium (Trachycardium) protosubrugosum Noetling, Mukerjee, p. 16. 1997 Trachycardium (Trachycardium) protosubrugosum (Noetling), Jain, p. 117, pl. XXI, ﬁgure 21. Material: Ten specimens (all are internal mould). Horizon and locality: Ramanian Stage; the Bermoti stream, Maniyara Fort. Waiorian Stage; Waior Village. Dimensions (mm):

Sp. no. Length Height Inﬂation

R2U/38 17.50 20.50 (117.14) 08.00 (45.71)

Remarks: The recorded examples from Kachchh, 7580 under the name Cardium protosubrugosum have been directly compared to the type mate- Noetling and observed to be matching very well in rial from Myanmar registered as GSI type no. all details, so the assignment.

Subfamily: Protocardiinae Keen, 1951 Genus: Nemocardium Meek, 1876 Type species: Cardium semiasperum Deshayes 1858, SD. Sacco, 1899. Eocene; France Subgenus: Nemocardium s.str.

Nemocardium (Nemocardium) bhagothorense Vredenburg 1928 Cardium (Nemocardium) bhagothorense Vredenburg, p. 445, pl. XXVII, ﬁgures 14–15.

Material: Ten specimens (all are internal mould).

Horizon and locality: Ramanian Stage; the Bermoti stream, Maniyara Fort. Waiorian Stage; Waior Village.

Dimensions (mm):

Sp. no. Length Height Inﬂation

R2U/134 33.70 33.70 (100.00) 23.20 (68.84)

Remarks: Recorded material contains very identity. Moreover, on direct comparison, with the characteristic representatives of the species Nemo- type material (GSI type no. 13405) these are found cardium (Nemocardium) bhagothorense Vreden- to be conspeciﬁc, thus, referred. burg, that there is hardly any need to qualify their

Subgenus: Discors Deshayes, 1858 Type species: Cardium discors Lamarck’ 1805; T. Eocene–Miocene; Europe–Asia 428 R P Kachhara et al

Nemocardium (Discors) naricum Vredenburg

Figure 26. Nemocardium (Discors) naricum Vredenburg W1/96. (a) Exterior of right valve, (b) exterior of left valve and (c) posterior view (×1.8). Bar scale = 10 mm.

1928 Cardium (Discors) naricum Vredenburg, p. 443, pl. XXVII, ﬁgures 4–6, 8–13, 16. 1997 Nemocardium (Discors) naricum Vredenburg, Jain, p. 119, pl. XXII, ﬁgures 12–13. Material: Five specimens (all are internal mould). Horizon and locality: Ramanian Stage; the Bermoti stream, Maniyara Fort. Waiorian Stage; Waior Village. Dimensions (mm):

Sp. no. Length Height Inﬂation

W1/96 22.20 24.40 (109.90) 17.70 (79.72)

Remarks: The representatives so collected no. 13400) at the GSI, Kolkata of Cardium from Kachchh are quite typical of the species (Discors) naricum Vredenburg. These are found and compared with the type material (GSI type to be conspeciﬁc.

Superfamily: Mactracea Lamarck, 1809 Family: Mactridae Lamarck, 1809 Subfamily: Lutrariinae Adams and Adams, 1856 Genus: Lutraria Lamarck, 1799 Type species: Mya lutraria Linn´e 1758; T. Recent; Mediterranean Subgenus: Lutraria s.str.

Lutraria (Lutraria)cf.phillipinarum Reeve

Figure 27. Lutraria (Lutraria)cf.phillipinarum Reeve L4/129. Exterior of left valve (×1). Bar scale = 10 mm. Lower Oligocene bivalves of Ramanian Stage 429

1936 Lutraria (Lutraria)cf.phillipinarum Reeve, Cox, p. 65, pl. VIII, ﬁgure 1 1997 Lutraria (Lutraria)cf.phillipinarum Reeve, Jain, p. 124, pl. XXIII, ﬁgure 1 Material: One specimen (internal mould). Horizon and locality: Ramanian Stage; Lakhpat Fort. Dimensions (mm):

Sp. no. Length Height Inﬂation

L4/129 45.00 25.50 (56.66) 13.00 (28.88)

Remarks: Solitary left valve though ill pre- GSI type no. 17419, of Lutraria (Lutraria)cf. served and slightly incomplete at the anterior and phillipinarum Reeve, illustrated by Cox (1936), posterior extremities, resembles so well to the that there is no hesitation about its identity.

Superfamily: Tellinacea de Blainville, 1814 Family: Tellinidae de Blainville, 1814 Subfamily: Tellininae de Blainville, 1814 Genus: Tellina Linne’, 1758 Type species: Tellina radiata Linne’ 1758; SD. Children, 1823. Recent; West Indies Subgenus: Arcopaginula Lamy, 1918 Type species: Tellina inﬂata Gmelin, 1791; M. Recent; Japan

Tellina (Arcopaginula) inﬂata Gmelin

Figure 28. Tellina (Arcopaginella) inﬂata Gmelin R2U/98. (a) Exterior of left valve and (b) dorsal view (×0.2). Bar scale = 10 mm.

1961 Arcopaginula inflata (Gmelin), Habe, p. 137, pl. 62, figure 7. 1969 Tellina (Arcopaginula) inflata Gmelin, Myra Keen, p. N613, figures E104, 10b. 1971 Tellina (Arcopaginula) inflata Gmelin, Shuto, p. 41, pl. X, figures 13–14. 2004 Tellina (Arcopaginula) inflata Gmelin, Mazumder, p. 102, pl. XII, figure 10. Material: Three specimens (all are internal mould). Horizon and locality: Ramanian Stage; the Bermoti stream, Maniyara Fort. Waiorian Stage; Waior Village. Dimensions (mm):

Sp. no. Length Height Inﬂation R2U/98 45.50 35.00 (76.92) 15.00 (32.96) 430 R P Kachhara et al

Remarks: Morphological features like medium posterior margin and smooth valve surface are size, ovate-rhomboid outline, strongly inequilat- enough to classify the studied material with Tel- eral conditions, moderate inflation with swollen lina (Arcopaginula) inflata Gmelin. Besides, these posterior, posterior third umbonal position, well are also tallying well with the figures cited in the rounded anterior margin, steeply sloping truncated synonymy, hence, confirms the identity.

Superfamily: Arcticacea Newton, 1891 Family: Arcticidae Newton, 1891 Genus: Arctica Schumacher, 1817 Type species: Arctica vulgaris (=Venus islandica Linne’ 1767); M. Pliocene; England

Arctica planata (J de C Sowerby)

Figure 29. Arctica planata (J de C Sowerby) L4/148. (a) Exterior of left valve and (b) anterior view (×0.8). Bar scale = 10 mm.

1959 Arctica planata (J de C Sowerby), White, p. 50, pl. XI, ﬁgure 7. Material: Five specimens (all are internal mould). Horizon and locality: Ramanian Stage; Lakhpat Fort. Dimensions (mm):

Sp. no. Length Height Inﬂation L4/148 57.60 47.40 (82.29) 36.10 (62.67)

Remarks: Lakhpat individuals are in form of marked posterior carina along with very good 23 internal moulds but very characteristics in hav- resemblance with ﬁgure 7 on pl. XI (White 1959) ing muscle scars as that of genus Arctica. In addi- leave no doubt in their identity as Arctica planata tion, trigonally ovate outline, much inequilateral (J de C Sowerby). conditions, well coiled subterminal umbones, well

Superfamily: Glossacea Gray, 1847 Family: Glossidae Gray, 1847 Genus: Glossus Poli, 1795 Type species: Glossus rubicundus (=Cardium humanum Linne’ 1758); M. Recent; N. Atlantic Subgenus: Cytherocardia Sacco, 1900 Type species: Isocardia cytheroides Mayer, 1868; OD. Miocene; France Lower Oligocene bivalves of Ramanian Stage 431

Glossus (Cytherocardia) cytheroides (Mayer)

Figure 30. Glossus (Cytherocardia) cytheroides Mayer L6/13. (a) Exterior of right valve and (b) dorsal view (×0.85). Bar scale = 10 mm.

1969 Glossus (Cytherocardia) cytheroides (Mayer), Keen and Casay, p. N657, ﬁgures E134, 9. Material: One specimen (internal mould). Horizon and locality: Ramanian Stage; Lakhpat Fort. Dimensions (mm):

Sp. no. Length Height Inﬂation

L6/13 42.20 35.40 (83.80) 28.60 (67.70)

Remarks: Lakhpat representative is tallying shape, well curved subterminal, and prominent very well and in full agreement with the ﬁgure umbo with surface sculpture in the form of ﬁne given by Keen and Casay (1969) for the geno- concentric growth lines all over the surface. These type from Miocene beds of France in every respect, characters are enough for the recorded specimen to i.e., medium size, rotund, obliquely semi-elliptical merge with cited species.

Superfamily: Corbiculacea Gray, 1847 Family: Corbiculidae Gray, 1847 Genus: Polymesoda Raﬁnesque, 1828 Type species: Cyclas caroliniana Bosc. 1801, OD. Recent; USA Subgenus: Geloina Gray, 1842 Type species: Cyrena zeylanica Lamarck, 1818, SD. Gray. Recent; East Indies

Polymesoda (Geloina) takaoi (Nagao and Otatume)

Figure 31. Polymesoda (Geloina) takaoi (Nagao and Otatume) R2U/18. Exterior of left valve (×1.65). Figure 32. Polymesoda (Geloina) takaoi (Nagao and Otatume) R2U/117. Exterior of left valve (×1.5). Bar scale = 10 mm. 432 R P Kachhara et al

1960 Geloina takaoi (Nagao and Otatume), Oyama et al, pl. XLVII, ﬁgure 2. Material: Five specimens (all are internal mould). Horizon and locality: Ramanian Stage; the Bermoti stream, Maniyara Fort. Dimensions (mm):

Sp. no. Length Height Inﬂation R2U/18 22.30 18.60 (83.40) 08.40 (37.66)

Remarks: Among the collected material, spec- size, surface ornamentation and umbonal position, imen R2U/18 matches so well with the ﬁgure 2(d) that there is no need to qualify its identity as Poly- on pl. XLVII (Oyama et al 1960), in overall shape, mesoda (Geloina) takaoi (Nagao and Otatume).

Superfamily: Veneracea Rafinesque, 1815 Family: Veneridae Rafinesque, 1815 Subfamily: Venerinae Rafinesque, 1815 Genus: Periglypta Jukes-Browne, 1914 Type species: Venus puerpera Linné 1758; OD. Recent; Pacific

Periglypta puerpera (Linn´e) var. granosa J de C Sowerby

Figure 33. Periglypta puerpera (Linne’) var. granosa J de C Sowerby W1/23. (a) Exterior of right valve and (b)anterior view (×0.92). Bar scale = 10 mm.

1840 Venus granosa J de C Sowerby, pl. XXV, figure 7. 1901 Venus granosa J de C Sowerby, Noetling, p. 197, pl. XII, figure 7. 1927 Antigona granosa (J de C Sowerby), Cox, p. 56, pl. III, figure 2. 1928 Venus (Omphaloclathrum) puerpera Linnévar.granosa J de C Sowerby, Vredenburg, p. 453. Material: Nine specimens (all are internal mould). Horizon and locality: Ramanian Stage; the Bermoti stream, Maniyara Fort. Waiorian Stage; Waior Village. Dimensions (mm):

Sp. no. Length Height Inﬂation

W1/23 46.00 38.00 (82.60) 26.00 (56.52)

Remarks: The specimens are compared with housed in Palaeontological laboratory of GSI, Vredenburg’s type material (GSI type no. 13530) Kolkata and found to match perfectly. Lower Oligocene bivalves of Ramanian Stage 433

Periglypta puerpera (Linn´e) var. aglaurae Brongniart

Figure 34. Periglypta puerpera (Linne’) var. aglaurae Brongniart W1/31. (a) Exterior of right valve and (b) dorsal view (×0.85). Bar scale = 10 mm.

1928 Venus (Omphaloclathrum) puerpera Linn´e, var. agalurae Brongniart, Vredenburg, p. 452. Material: 60 specimens (all are internal mould). Horizon and locality: Ramanian Stage; the Bermoti stream, Maniyara Fort, and Lakhpat Fort, Waiorian Stage; Waior Village. Dimensions (mm):

Sp. no. Length Height Inﬂation W1/31 50.50 39.50 (78.21) 30.50 (60.39)

Remarks: The species is distinguishable from well exhibited by the material recorded here, there- the preceding form in respect of having a perfect fore, these belong to the species namely Periglypta regularly curved anterior margin. This diﬀerence is puerpera (Linne’) var. aglaurae Brongniart.

Subfamily: Pitarinae Stewart, 1930 Genus: Pitar R¨omer, 1857 Type species: Venus tumens Gmelin, 1791; M. Recent; West Africa Subgenus: Pitar s.str. Pitar (Pitar) porrecta Koenen

Figure 35. Pitar (Pitar) porrecta Kaenen R2U/131. (a) Exterior of left valve and (b) dorsal view (×1.6). Bar scale = 10 mm. 434 R P Kachhara et al

1900 Pitar Porrecta Koenen, Sacco, p. 20, pl. IV, ﬁgure 30. 1928 Cytherea (Pitar) porrecta Koenen, Vredenburg, p. 451. 2004 Pitar porrecta Koenen, Lyngdoh, p. 96, pl. XII, ﬁgure 7. Material: Six specimens (all are internal mould). Horizon and locality: Ramanian Stage; the Bermoti stream, Maniyara Fort. Waiorian Stage; Waior Village. Dimensions (mm):

Sp. no. Length Height Inﬂation

R2U/131 24.70 19.80 (80.16) 12.00 (48.58)

Remarks: Our specimens are well comparable respect, thus, the assignment. to the type material (GSI type no. 13525) in every

Genus: Callista Poli, 1791 Type species: Venus chione Linne’ 1758; SD Meek, 1876. Recent; Mediterranean Subgenus: Callista s.str. Callista (Callista) yawensis Cotter

Figure 36. Callista (Callista) yawensis (Cotter) L4/165. (a) Exterior of right valve and (b) dorsal view (×1). Bar scale = 10 mm.

1923 Meretrix (Callista) yawensis Cotter, p. 28, pl. II, ﬁgures 2–4. Material: Two specimens (both are internal mould). Horizon and locality: Ramanian Stage; Lakhpat Fort. Dimensions (mm):

Sp. no. Length Height Inﬂation L4/165 41.00 31.00 (75.60) 20.50 (50.00)

Remarks: The type material (GSI type no. margins, evenly merging with slightly convex ven- 12354–56) from Myanmar was not available at the tral margin, moderately inclined and straight time of visit to GSI, Kolkata, however, sp. no. antero-dorsal margin, except for a small concavity L4/165 is matching very well with the ﬁgure of the adjacent to umbo, elongate and very feebly con- type no. 12355 in every respect as elongated trig- vex gently inclined postero-dorsal margin, thus, the onal outline, broadly rounded anterior, posterior reference. Lower Oligocene bivalves of Ramanian Stage 435

Callista (Callista) pseudoumbonella Vredenburg

Figure 37. Callista (Callista) pseudoumbonella Vredenburg W1/39. (a) Exterior of left valve and (b) dorsal view (×0.75). Bar scale = 10 mm.

1928 Cytherea (Callista) pseudoumbonella Vredenburg, p. 450, pl. XXIX, figures 10–13; pl. XXX, figures 1–3, 5–6. 1997 Callista pseudoumbonella Vredenburg; Jain, p. 143, pl. XXV, figures 17, 20. Material: 29 specimens (all are internal mould). Horizon and locality: Ramanian Stage; the Rakhdi Dam, Lakhpat Fort. Waiorian Stage; Waior Village. Dimensions (mm):

Sp. no. Length Height Inﬂation R1/24 40.50 32.00 (79.01) 24.00 (59.25) W1/39 49.50 41.00 (82.82) 29.20 (58.98)

Remarks: It is one of the most common species GSI type no. 13419, there is no doubt in their identity and after comparing with the type material, especially, as Callista (Callista) pseudoumbonella Vredenburg.

Callista (Callista) pseudoumbonella Vredenburg var. globosa Jodhawat 2011 Callista (Callista) pseudoumbonella Vredenburg var. globosa Jodhawat, Kachhara et al,p.25,pl. I, ﬁgures 6 a, b. Material: One complete specimen (internal mould). Horizon and locality: Ramanian Stage; Lakhpat Fort. Dimensions (mm):

Sp. no. Length Height Inﬂation L6/8 44.50 34.30 (77.07) 31.50 (70.78)

Remarks: In overall conﬁguration it is very inﬂation which is 70% instead of 62% and com- much similar to the individuals of Callista (Cal- ing from a lower horizon, i.e., Oligocene instead of lista) pseudoumbonella leaving aside its strong Miocene.

Subfamily: Tapetinae Adams and Adams, 1857 Genus: Paphia Röding, 1798 Type species: Paphia alapapilionis Röding, 1798; SD. Dall, 1902. Recent; West Pacific Subgenus: Callistotapes Sacco, 1900 Type species: Venus vetula Basterot, 1825; OD. Oligocene–Recent; Europe, Asia 436 R P Kachhara et al

Paphia (Callistotapes) pseudoliratus Vredenburg

Figure 38. Paphia (Callistotapes) pseudoliratus Vredenburg W1/82. (a) Exterior of left valve and (b) dorsal view (×1.25). Bar scale = 10 mm.

1928 Tapes (Callistotapes) pseudoliratus Vredenburg, p. 457, pl. XXXI, figures 2–5. 1992 Paphia (Callistotapes) pseudoliratus Vredenburg, Tiwari, p. 148, pl. XVI, figures 2–4. 2004 Paphia (Callistotapes) pseudoliratus Vredenburg, Lyngdoh, p. 107, pl. XIV, figures 1–2. Material: Two specimens (both are internal mould). Horizon and locality: Ramanian Stage; the Bermoti stream, Maniyara Fort. Waiorian Stage; Waior Village. Dimensions (mm):

Sp. no. Length Height Inﬂation

R2U/136 40.80 29.00 (71.07) 15.60 (38.23) W1/82 24.60 17.00 (69.10) 09.50 (38.61) Remarks: Both the individuals on direct com- 13431) found to be conspeciﬁc. parison with Vredenburg’s material (GSI type no.

Paphia (Callistotapes) virgatus (J de C Sowerby)

Figure 39. Paphia (Callistotapes) virgatus (J de C Sowerby) R2U/159. (a) Exterior of left valve and (b) dorsal view (×1.3). Bar scale = 10 mm.

1840 Pullastra virgatus J de C Sowerby, pl. XXV, ﬁgure 9. 1928 Tapes (Callistotapes) virgatus (J de C Sowerby), Vredenburg, p. 456. 1997 Paphia (Callistotapes) virgatus (J de C Sowerby) Jain, p. 150, pl. XXVI, ﬁgures 5–8. Material: Four specimens (all are internal mould). Horizon and locality: Ramanian Stage; the Bermoti stream, Maniyara Fort. Waiorian Stage; Waior Village. Dimensions (mm):

Sp. no. Length Height Inﬂation R2U/159 31.50 21.60 (68.57) 15.20 (48.25) Lower Oligocene bivalves of Ramanian Stage 437

Remarks: All the four individuals are very typ- observed to be fully tallying in every respect, thus ical of the species which on comparison with the the recorded material represents the species Paphia material lying at GSI, Kolkata (type no. 13432) are (Callistotapes) virgatus (J de C Sowerby).

4. Age of the Ramanian Stage Repository

As pointed out earlier that the age of the Nari All the specimens of the present collection of fossil Series and corresponding sequences in India is Bivalvia (described and photographed) have been not very precise. About dating of the Lower Nari deposited in the Department of Geology, M.L. there is no valid proof. On the other hand, the Sukhadia University, Udaipur 313 002. Upper Nari seems to transgress into Miocene. Recorded bivalve taxa have different geologic ranges Oligocene/Oligocene to Miocene/Lower Acknowledgements Miocene with few long ranging or coming from Eocene. This is reflected in the given table. Still The authors are indebted to the Head, Department there are few forms which are important in light of of Geology, M.L. Sukhadia University, Udaipur the geological range for example Arctica planata (J 313002 for providing the facilities and encourage- de C Sowerby) which ranges from Lower Eocene to ment. The authors wish to acknowledge the finan- Lower Oligocene in Europe, Polymesoda (Geloina) cial assistance received from University Grants takoi (Nagao and Otatume) occurring in Lower Commission, New Delhi (No. 33-46/2007 (SR)). Oligocene strata of Japan and the genus Glossus Constructive comments from anonymous review- (Glossus) ranging from Lower Oligocene to Recent ers are also gratefully acknowledged. The authors indicating an age of Lower Oligocene for the express their thanks to the authorities of GSI, Ramanian Stage. Few taxa are said to occur Kolkata to accord the permission and make avail- only in Lower Oligocene are also reported Trachy- able the type specimens for direct comparison. cardium (Trachycardium) sindiense Vredenburg, Nemocardium (Nemocardium) bhagothorense Vre- References denburg, Nemocardium (Discors) naricum Vreden- burg, Trisidos semitorta (Lamarck), Pitar (Pitar) d’Archiac A 1850 Hist. Prog. Geol. Soc. Geol. France 3 1–624. porrecta Koenen, Periglypta puerpera (Linne’) var. d’Archiac and Haime J 1854 Description des Animaux Fos- aglaurae Brongniart. There are others which are siles du Groupe Nummulitique de l’Inde; Paris: Gide and long ranging but do not occur in the strata J. Baudry, pp. 1–373. Biswas S K 1965 A new classification of the tertiary rocks older to Oligocene, e.g., Pecten (Amussiopecten) of the Kutch, India; Bull. Geol. Min. Metall. Soc. India labadyei d’Archiac and Haime, Callista (Callista) 35 1–6. pseudoumbonella Vredenburg, Ostrea (Ostrea) pro- Biswas S K 1971 Notes on the Geology of Kutch; Quart. J. toimbricata Vredenburg and Periglypta puerpera Geol.Min.Met.Soc.India43(4) 223–235. (Linne’) var. granosa J de C Sowerby. Few Biswas S K 1973 Time stratigraphic classification of the Tertiary rocks of Kutch – A Revision and Amendments; taxa are reportedly occurring in Miocene strata Quart.J.Geol.Min.Met.Soc.India.44(3) 223–235. but recorded here from the Ramanian Stage of Biswas S K 1992 Tertiary stratigraphy of Kutch; J. Palaeon- Oligocene. One taxon, viz., Callista (Callista) tol. Soc. India 37 1–29. yawensis (Cotter) of Upper Eocene of Mayanmar Biswas S K and Raju D S N 1971 Note on the has been recorded here from Oligocene rocks. rock-stratigraphic classification of Tertiary sediments of Kutch; Quart.J.Geol.Min.Met.Soc.India43(3) Therefore, the age of the Ramanian Stage is 177–180. Oligocene and more so Lower Oligocene falling Chatterji A K and Mathur U B 1966 A note on the Nari in conformity with the age derived from the Series of Kutch, Gujarat; Bull.Geol.Soc.India3(1) foraminifer taxon Nummulites fichteli. 9–11. Geological ranges of Arctica planata, Polymesoda Cossmann M and Pissarro G 1927 The Mollusca of the Ranikot series (together with some species from the (Geloina) takoi and Glossus canbeusedwithcon- Cardita beaumonti Beds); Palaeontologia Indica, Geol. fidence for dating of the Ramanian Stage which Surv. India Memoir 10(2) 1–31, pls. I–IV. is coming to be Lower Oligocene. Other taxa Cotter G de P 1923 The Lamellibranchiata of the Eocene of which are shown to restrict to the Ramanian Stage Burma; Palaeontologia Indica, Geol. Surv. India Memoir should be taken as locally important as these 7(2) 1–24, pls. I–VIII. Cox L R 1927 Neogene and Quaternary molluscan from taxa are being reported one or the other from the Zanzibar Protectorate; Report on the Palaeontology even Miocene strata of other areas in Pakistan, of Zanzibar Protectorate. Zanzibar Govt. Report: 13–102, Kathiawar, Meghalaya and Mizoram. pls. III–XIX. 438 R P Kachhara et al

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MS received 22 December 2010; revised 14 July 2011; accepted 12 October 2011