Pala¨ontol Z (2009) 83:419–430 DOI 10.1007/s12542-009-0033-5
RESEARCH PAPER
A new lobster Paraclytia valashtensis (Crustacea, Decapoda, Nephropidae) from the Late Cretaceous of the central Alborz Range, Iran Lucy Martha Evelyn McCobb Æ Vachik Hairapetian
Received: 28 April 2009 / Accepted: 17 June 2009 / Published online: 8 July 2009 Ó Springer-Verlag 2009
Abstract A new species of Late Cretaceous clawed lobster, Paraclytia valashtensis, is described. The discovery is a notable addition to the sparse decapod fossil record of Iran, and this is the first record of the genus outside central Europe. The four previously known species of Paraclytia are from Germany and the Czech Republic, so this discovery represents a significant expansion of the palaeogeographic range of the genus.
Abbreviations
Keywords Decapoda Nephropidae Paraclytia Lobster Late Cretaceous Iran
List of symbols b1 Hepatic groove c Postcervical groove e Cervical groove b Antennal groove x ‘Adductor testis’ region x Diamond-shaped protuberance TM Thoracic median carina SO Supraorbital carina I Intermediate carina B Branchial carina A Antennal carina L Lateral carina PO Postorbital spine T Tubercle SP Supra-postorbital carina
Kurzfassung Eine neue Art oberkretazischer Hummer wird als Paraclytia valashtensis beschrieben. Dieser Fund stellt eine wichtige Erga¨nzung des bisher sehr spa¨rlichen Fossilberichtes von Decapoden aus dem Iran dar und ist gleichzeitig das erste Vorkommen dieser Gattung außerhalb Mitteleuropas. Die bisher beschriebenen vier Arten von Paraclytia stammen ausnahmslos aus Deutschland oder der Tschechischen Republik, so dass der neue Fund eine bedeutende Erweiterung der pala¨ogeographischen Reichweite der Gattung darstellt. Schlu¨sselwo¨rter Decapoda Nephropidae Paraclytia Hummer Obere Kreide Iran
L. M. E. McCobb (&) Geology Department, National Museum of Wales, Cathays Park, Cardiff CF10 3NP, UK e-mail:
[email protected] V. Hairapetian Department of Geology, Islamic Azad University, Khorasgan Branch, P.O. Box 81595-158, Esfahan, Iran e-mail:
[email protected]
Institutional abbreviations NMW National Museum of Wales NMP National Museum, Prague IGWG Institut fu¨r Geologische Wissenschaften und Geiseltalmuseum, Halle BGR Bundesanstalt fu¨r Geowissenschaften und Rohstaffe, Hannover
Introduction There have been few reported occurrences of fossil decapod crustaceans from Iran. Eryma bedelta (von Quenstedt 1857) was recorded in the Middle Jurassic (Aaleninian) of northern Iran (Fo¨rster and Seyed-Emami 1982). A Miocene portunid crab from Iran was reported in an abstract by Toraby and Yazdi (2002), but a full description was not
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published. Feldmann et al. (2007) erected a new family (Tricarinidae), genus (Tricarina) and species (T. gadvanensis) of a dorsoventrally flattened palinuroid lobster, based on a single specimen found in a well core from the Early Cretaceous (Barremian–Aptian) Gadvan Formation in southwestern Iran. Bro¨nnimann (1977) reported coprolites from the Jurassic of Iran with an internal structure characteristic of decapods. Yazdi et al. (2009) recently reported decapods of Early Cretaceous (Albian) age from Isfahan in central Iran, including the raninid crab Notopocorystes xizangensis Wang, 1981, callianassoid (ghost shrimp) remains and fragments of the lobster ?Hoploparia sp. The discovery of a new species of the Late Cretaceous lobster Paraclytia is an important addition to the Iranian fossil record of decapods; all previous records of the genus are restricted to Germany and the Czech Republic, so this find represents a significant expansion of its palaeogeographical range.
Materials and methods The specimens figured herein were coated in ammonium chloride sublimate prior to photography, and were directionally lit from a low-angle northwesterly direction to highlight key features. The holotype of Paraclytia valashtensis n. sp. is deposited in the National Museum of Wales, Cardiff, UK. Descriptive terminology follows Tshudy et al. (2007). The following material of the previously known Paraclytia species was provided by various institutions for comparative purposes: Paraclytia nephropica Fritsch, 1887: Cast of counterpart (NMP 03458) of specimen figured by Fritsch and Kafka (1887: pl. 4, Fig. 1; NMP 03459: lateral view of cephalothorax and abdomen, plus one claw) plus photographs of NMP 03458 and 03459; cast and photograph of NMP 03466 (dorsal view of cephalothorax and abdomen, plus one claw), figured by Fritsch and Kafka (1887: pl. 4, Figs. 5, 6). Photograph of a cephalothorax and abdomen figured by Mertin (1941: pl. 2, Fig. 1), from Weisser Berg near Prague. Paraclytia boetticheri Mertin, 1941: Cast of IGWG MLU.GP.Mer1941.2.6, a claw figured by Mertin (1941: pl. 2, Fig. 6). Paraclytia westfalica Mertin, 1941: Cast of IGWG MLU.GP.Mer1941.2.7, a cephalothorax and abdomen figured by Mertin (1941: pl. 2, Fig. 7). Paraclytia nephropiformis (von Schlu¨ter 1879): Original specimen of BGR X273, comprising cephalothorax, abdomen and a claw, figured by Mertin (1941: pl. 2, Fig. 8).
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Geographic and stratigraphic setting Rocks of Cretaceous age are widely exposed to the south of Chalus town, on the northern flank of the central Alborz Range, northern Iran. Cartier (1971) established the volcano-sedimentary Chalus Formation with five members, ranging from Barremian to Coniacian (?) in age. The Chalus Formation is overlain disconformably by marls and marly limestones (member K21,m) of an unnamed formation, which has received only scant treatment as a short map report by Vahdati et al. (2001). The authors gave a Campanian age, based on a few planktonic foraminiferan taxa, including Globotruncana elevata and G. ventricosa. The new specimen of Paraclytia was collected at N36°320 13.7200 ; E51°170 41.0400 , from a marly limestone bed in the unnamed formation, on the southeastern bank of Valasht Lake, 17 km southwest of Chalus (Fig. 1). The specimen is well preserved, if slightly crushed, and retains the original cuticle of the carapace. It is virtually complete, comprising cephalothorax, fragmentary pereiopods, abdomen and tail fan, although the chelae are absent. One lateral half of the lobster is preserved, and a dorsal view of the abdominal terga and tail fan is also visible. Associated with the lobster are numerous bivalves (mainly inoceramids) and rare fragments of poorly preserved ammonites. A microfacies analysis revealed a silty/ sandy bioclastic wackestone, probably representing a proximal part of the outer shelf carbonate palaeoenvironment (Hasan Hejazi, personal communication November 2008). However, more detailed sedimentological study is required to get precise information on depositional setting. Systematic palaeontology Order Decapoda Latreille, 1802 Infraorder Astacidea Latreille, 1802 Superfamily Nephropoidea Dana, 1852 Family Nephropidae Dana, 1852 Subfamily Nephropinae Dana, 1852 Genus Paraclytia Fritsch, 1887 Type species: Paraclytia nephropica Fritsch, 1887, by original designation. Discussion: Paraclytia was erected by Fritsch (in Fritsch and Kafka 1887) to accommodate Late Cretaceous (Turonian) lobsters with the general form of Nephrops, but distinguished from it by having lateral spines along the full length of the rostrum, as opposed to only on the distal rostrum in Nephrops, and by always possessing three pairs of thoracic carinae. At the time, the number of thoracic carinae was viewed as a variable feature in Nephrops, which was thought to possess either two or three pairs, but
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Fig. 1 Map showing the type locality of P. valashtensis in the central Alborz Range, northern Iran
Jenkins (1972) erected a new genus, Metanephrops, for those species with three pairs of carinae. Metanephrops is the most diverse extant lobster genus known, with 17 extant and three fossil species (Tshudy et al. 2007). The two genera have very similar cephalothoraces, but Paraclytia is most clearly distinguished from Metanephrops by features of the abdomen and telson (Tshudy et al. 2007). The abdominal terga and pleura of Paraclytia have a unique sculpture, comprising deep transverse furrows and prominent longitudinal ridges. The telson of Paraclytia has submedian carinae that converge posteriorly, while those of Metanephrops diverge. Mertin (1941) provided the first (and only) thorough treatment of the genus, describing four species, all from the Upper Cretaceous of central Europe. The species were distinguished on the basis of the positions of thoracic carinae, the nature and position of a protuberance above the
hepatic groove (b1) and the strength and characteristics of the abdominal sculpture (Tables 1, 2).
Paraclytia valashtensis n. sp. Figs. 2 and 3, Tables 1 and 2 Etymology: After the type locality. Holotype: NMW 2008.9G.1, comprising cephalothorax, fragmentary pereiopods, abdomen and tail fan. Type locality: Southeastern bank of Valasht Lake, 17 km south west of Chalus (co-ordinates N36°320 13.7200 ; E 51°170 41.0400 ). Type horizon: Marly limestone bed in an unnamed formation overlying the Chalus Formation (Campanian Stage).
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Table 1 Major distinguishing features of Paraclytia species Terga sculpture
Pleura ornament
Coniacian to Rounded tubercle Maastrichtian
Weak
Weak
P. boetticheri
Coniacian
Rounded tubercle
Centre zone with long carinae, rear with rounded tubercles
Two strong spines down centre, edges thickened with some small spines
P. westfalica
Coniacian to Santonian
Elongate oblong tubercle, Centre zone with long carinae, rear Two strong spines down centre, edges set in a deeper position with elongate tubercles attached thickened with some small spines than branchial carina to posterior edge
Species
Age (stage)
P. nephropica
Embossment above groove b1
P. nephropiformis Coniacian to Elongate oblong tubercle Maastrichtian in extension of branchial carina
Centre zone and rear with long Numerous small to medium carinae, separate from posterior tubercles; also two strong edge spines down centre on pleura 3–5
P. valashtensis
Centre zone with long carinae, rear Two strong spines down centre, edges with elongate tubercles or thickened with some small spines carinae, attached to posterior edge at least on first two terga
Campanian
Elongate oblong tubercle in extension of branchial carina
After Mertin, 1941, p. 171, with modifications
Type material: A single specimen, the holotype, NMW 2008.9G.1. Diagnosis: Cephalothorax with relatively deep flanks, depth around 60% of maximum cephalothorax length (excluding rostrum). Elongate spine in field defined by hepatic groove (b1), positioned level with branchial carina. Terga with strong ornamentation of longitudinal ridges and tubercles on front and rear fields; tubercles on rear field produced by thickening of posterior margin on at least the first two terga. Pleura with two strong spines down the middle and smaller spines on gently thickened lateral margins, otherwise smooth. Description: Only one lateral half of the cephalothorax is visible, which is slightly crushed; subcylindrical, tapering anteriorly, rostrum not preserved. Preserved length of cephalothorax along mid-dorsal line is 33.5 mm; maximum preserved length from posterior to anterior margin is 41.5 mm. Maximum lateral depth, from dorsal to ventral margin, occurs just posterior of where postcervical groove meets posterior margin and equals 25 mm, around 60% of maximum length. Postcervical groove (c) very well defined dorsally, deep and broad, approximately perpendicular to dorsal margin for around a quarter of carapace height. The groove cannot be traced for its entire length due to damage to the midflank area of the cephalothorax; however, interpolation across the damaged area suggests that for the remainder of its length, the postcervical groove extends obliquely downward and forward. Postcervical groove very shallow ventral of where it meets hepatic groove (b1), ending a short distance from ventral margin of carapace. Cervical groove (e) well developed, deep and wide; merges ventrally with much shallower antennal groove (b), which curves around anteroventrally, following a roughly
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semicircular path. Hepatic groove (b1) narrow and very shallow, connecting c and e, and bordering ventrally a slightly swollen ‘adductor testis’ region (x). The point where the cervical (e), antennal (b) and hepatic (b1) grooves meet marks the dorsal limit of a prominent, diamond-shaped protuberance (x), delimited dorsolaterally by b and b1, and ornamented with six fine tubercles. Ventral of x, carapace has a dense ornament of coarse tubercles, which diminish in size and become more scale-like towards the ventral margin. Posterior region of carapace with four pairs of prominent carinae, a pair of thoracic median carinae (TM) running along the dorsal margin and three pairs of carinae on thorax flanks. Each thoracic median carina comprises four elongate, closely spaced spines, running from posterior margin of carapace to postcervical groove (c). Anterior of postcervical groove, median carinae continue as supraorbital carinae (SO), made up of similar closely spaced, elongate spines. The specimen is incomplete in this area, so the full extent of the supraorbital carinae is unknown, but in other known species of Paraclytia, they extend to the base of the rostrum. The thoracic carina closest to the dorsal margin, the intermediate carina (I), is ornamented with four elongate spines lying very close together, and is angled upwards slightly towards the dorsal margin so that the distance separating it from the median carina decreases by about a third moving from posterior margin to postcervical groove (c). Intermediate carina continues a short distance anterior of c, as two (possibly three) elongate spines, labelled here the supra-postorbital carina (SP), although this is subject to revision should homologous structures be discovered in other lobster species. The second (branchial) thoracic carina (B) runs roughly parallel to the intermediate carina and is joined to it by a
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Table 2 Major morphological features of Paraclytia species
After Mertin 1941, p 171, with modifications
thickened ridge running along the anterior edge of the posterior margin furrow of the carapace, and ornamented with medium-sized, rounded, well spaced out tubercles. Branchial carina is incomplete due to damage, but its wellpreserved posterior section has an ornament of mediumsized, rounded, flat, scale-like tubercles that are relatively well spaced out. Like the median and intermediate carinae, it apparently reaches the postcervical groove (c), and continues immediately after c as a large elongate tubercle
lying above the hepatic groove (b1) in line with the branchial carina, and beyond the cervical groove (e) as an antennal carina (A). This area of the carapace is poorly preserved, but the antennal carina appears to comprise elongate spines that continue to the anterior margin. In the anterior region of the carapace, the carinae on each flank converge slightly anteriorly; a metorbital spine lies roughly equidistant between the second and third carinae, close to the anterior margin.
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A new lobster Paraclytia valashtensis from the Late Cretaceous Paraclytia valashtensis n. sp. All photographs are of holotype, NMW 2008.9G.1. a left lateral view of whole specimen showing nearly complete cephalothorax (no rostrum), abdomen, telson and partial pereiopods, b left lateral view of posterior abdomen, telson and partial pereiopods, c left lateral view of cephalothorax (no rostrum) and partial pereiopods, d dorsal view of abdomen, e dorsal view of cephalothorax (right lateral half not preserved), f dorsal view of telson, g right lateral view of telson. Scale bars: 10 mm
b Fig. 2
A third (lateral) thoracic carina (L) originates at the posterior margin and runs close to the ventral margin and subparallel to it. At its anterior end, it diverges from the ventral margin, curving gently upwards to meet the postcervical groove (c). Beneath this upwards curve are a
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small number of scales that diminish in size towards the ventral margin. The lateral carina stops at the postcervical groove, is not connected to the intermediate and branchial carinae and is narrower and smaller, with a finer ornament comprising close-set flat scales, which increase in size slightly anteriorly as the carina widens slightly. The posterior margin is poorly preserved, but a short section of wide, gently convex border is visible, ornamented with a round, medium-sized tubercle; the border is separated from the flank of the cephalothorax by a relatively wide, deep furrow.
Fig. 3 Paraclytia valashtensis n. sp. a left lateral view of holotype, NMW 2008.9G.1, and b line drawing of cephalothorax, showing key morphological features. SO supraorbital carina, TM thoracic median carina, I intermediate carina, B branchial carina, L lateral carina, A antennal carina, PO postorbital spine, SP supra-postorbital carina, c postcervical groove, b1 hepatic groove, e cervical groove, b antennal groove, x ‘adductor testis’ region, x diamondshaped protuberance, t tubercle. Scale bars: 10 mm
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A relatively dense ornament of fine, evenly distributed pits covers the carapace. All abdominal somites are preserved, the fifth and sixth smaller and less complete than the first to fourth. Pleuron not preserved on first somite. Pleuron on second somite incomplete and damaged, but showing a smooth surface with small scale-like tubercles erupting from gently thickened lateral margins. Complete pleura preserved on somites three to six; pleura three to five cordate with subtly posteroventrally directed, sharp, spine-tipped ends. Pleuron on sixth somite subtriangular with a curved anteroventral margin and straight posteroventral margin. Mid-line of pleura three to five ornamented with two coarse spines; tiny to small, scale-like tubercles present along slightly thickened lateral margins of all pleura. Terga have a wide, deep transverse groove just posterior of mid-length, running relatively straight across middle third of tergum, curving back posteriorly in lateral thirds to the posteroventral corners. Transverse groove continues into pleuron, becoming extremely narrow where tergum and pleuron meet and then widening out again on pleuron, extending to between one-quarter and one-third pleuron length. Lateral margins of terga with closely spaced, medium to coarse spines. Anterior region of terga ornamented with longitudinal carinae, which are progressively longer laterally and are gently bowed towards the dorsal midline. Posterior region of terga more densely ornamented than anterior, with longitudinal carinae in the centre zone, which diminish in size laterally to oblong and rounded tubercles. On the two anteriormost terga, carinae/tubercles in posterior region are continuous with the thickened posterior edge; the ornament is not well enough preserved on the other terga to determine whether this is the case along the full length of the abdomen. Fragments of four pereiopods preserved, distal ends and points of articulation with cephalothorax not visible. Chelae not preserved. Anteriormost pereiopod is a small fragment comprising distal end of basis, ischium and proximal end of merus, which has a longitudinal furrow and an ornament of coarse, flaky scales. Second pereiopod preserves the distal end of the basis, the ischium and a long portion of the merus. The ischium has a longitudinal furrow slightly offset from the midline, and a sculpture of flaky scales either side of the furrow. The merus has two longitudinal furrows delineating three sections of approximately equal width, which are ornamented with much smaller scales than the ischium. Two further pereiopod fragments lie a short distance beyond the preserved end of the merus, a short cylinder and a flat subtriangular fragment with a raised rim, which is ornamented with small, scale-like spines. Their fragmentary, isolated nature makes it is impossible to establish their position on the pereiopod. The third pereiopod preserved shows the distal end of the
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L. M. E. McCobb, V. Hairapetian Fig. 4 Previously known species of Paraclytia. a P. nephropica, c right lateral view of complete specimen (NMP 03459); b P. boetticheri, cast of a claw (IGWG MLU.GP.Mer1941.2.6), figured by Mertin 1941, in pl. 2, Fig. 6; c P. westfalica, right lateral view of cast of cephalothorax and abdomen (IGWG MLU.GP.Mer1941.2.7), figured by Mertin 1941, in pl. 2, Fig. 7; d–f P. nephropiformis, almost complete specimen (BGR X273), figured by Mertin 1941, in pl. 2, Fig. 8; d left lateral view of cephalothorax; e left lateral view of cephalothorax, abdomen, telson and claw; f left lateral view of abdomen, telson and posterior cephalothorax. Scale bars: 10 mm
ischium and part of the merus, which has a single longitudinal furrow slightly offset from the midline, and an ornament of coarse flaky scales that diminish in size distally. The fourth pereiopod is much thinner than the other three, and comprises a long section of the merus, tapering distally, with a fine longitudinal furrow and a subtle ornament of fine scales. Uropods approximately one and a half times length of telson. Exopod with diaeresis and a weak longitudinal rib; lateral border with small, flaky scales. Endopods poorly preserved but apparently also have longitudinal ribs. Telson with subrectangular outline, with lateral margins gently bowing out. Central region not preserved; lateral regions each with a longitudinal furrow, which converge slightly posteriorly. Lateral margins of telson gently swollen anteriorly, ornamented along their whole length with very small, flaky scales. Remarks: P. valashtensis has a cephalothorax that is relatively deeper in lateral view than other known species of Paraclytia, all of which have a maximum carapace depth of around half maximum carapace length (excluding rostrum), compared with around 60% of maximum length in the Iranian species. As a result, the other species of Paraclytia all have a shallower carapace in lateral view. Other differences are discussed below for each species, and are summarised in Tables 1 and 2.
Discussion Comparison with other species of Paraclytia Paraclytia nephropica Fritsch, 1887 Figure 4a; Tables 1 and 2. Material examined. National Museum, Prague provided casts of the counterpart (NMP 03458) of the specimen figured by Fritsch and Kafka (1887: pl. 4, Fig. 1; NMP 03459: lateral view of cephalothorax and abdomen, plus one claw), and of NMP 03466 (dorsal view of cephalothorax and abdomen, plus one claw), figured by Fritsch and Kafka (1887: pl. 4, Figs. 5 and 6). Photographs of specimens NMP 03458, 03459 and 03466 were also provided. A photograph of a specimen (cephalothorax and abdomen) of
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P. nephropica figured by Mertin (1941: pl. 2, Fig. 1), from Weisser Berg near Prague was provided by the Museum fu¨r Mineralogie und Geologie, Dresden. P. nephropica has the intermediate and branchial thoracic carinae further up on the flank (closer to dorsal margin) than P. valashtensis, and the lateral carina is only faintly expressed, while it is very prominent in the Iranian species. The median and intermediate, and intermediate and branchial carinae are closer to each other in P. nephropica than in P. valashtensis. The ornament below the lateral carina comprises small to medium, rounded tubercles in P. nephropica, while P. valashtensis has coarse flaky scales. Although Mertin’s (1941) description of P. nephropica states that it has no embossments above the hepatic groove (b1), one specimen (NMP 03459) clearly has a rounded tubercle lying well below the level of the branchial carina, around midway between b1 and the height of the carina. The specimen of P. valashtensis is damaged in this area, but an elongate tubercle can be seen, level with the branchial carina. The abdominal sculpture is much more weakly expressed in P. nephropica than in other species, including P. valashtensis. Paraclytia boetticheri Mertin, 1941 Figure 4b; Tables 1 and 2. Material examined: IGWG sent a cast of the only available specimen of this species (IGWG MLU.GP. Mer1941.2.6), a claw that was figured by Mertin (1941). Although efforts were made to locate others in various museums, none was found. Since no claws are preserved on P. valashtensis, direct comparison is impossible. The following remarks are therefore based on Mertin’s (1941) description and illustrations of P. boetticheri. Mertin’s (1941) line diagram (p. 170, Fig. 6) and data table (p. 171) suggest that the relative spacing of the thoracic carinae is similar in P. boetticheri and P. valashtensis. However, his photographs (pl. 2, Figs. 2, 3) reveal that the intermediate carina is closer to the dorsal margin of the carapace in the former, where the intermediate carina comprises ‘5–8’ spines behind the postcervical groove, while that of P. valashtensis comprises only four elongate spines. In both fossils, a small number of rounded tubercles link the intermediate carina to the posterior edge of the carapace. The branchial carina in P. boetticheri is described by Mertin (1941) as typically a smooth border but with some specimens showing that it was also occupied by spines. P. valashtensis is damaged in this area but a short posterior section of the branchial carina shows that it was ornamented with large, rounded, scale-like tubercles. The lateral carina is more clearly defined in the Iranian fossil and ornamented with medium to large scales, while that of P. boetticheri is less pronounced and has smaller scales. Mertin (1941) describes P. boetticheri as having a rounded peak in a
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relatively deep-set position within the field dorsal of hepatic groove b1. P. valashtensis has an elongate tubercle set well above b1, level with the branchial carina. The abdominal sculpture is similar in both lobsters, with deep transverse furrows and longitudinal tubercles or carinae on the terga. The tubercles on the rear terga fields of P. boetticheri arise from a thickening of the posterior edge, a condition that can only be observed on the first two terga of the Iranian fossil. The ornament is too poorly preserved on the remaining terga to determine whether it is joined to or separate from the posterior edge. The shape and ornamentation of abdominal pleura is similar in both, with two (usually) or three large spines down the centre and the outer edges thickened and ornamented with small spines. Also, the transverse furrow on each terga continues into the pleuron in both species. Paraclytia westfalica Mertin, 1941 Figure 4c; Tables 1 and 2. Material examined: IGWG, Halle sent a cast of a single specimen (IGWG MLU.GP.Mer1941.2.7), a cephalothorax and abdomen figured by Mertin (1941: pl. 2, Fig. 7). P. westfalica differs from P. valashtensis in the position of the tubercle above hepatic groove b1, which is set below the level of the branchial carina in the former, but level with it in P. valashtensis. The abdominal sculpture is similar in both, with longitudinal tubercles or carinae on front and rear fields of the terga, and pleura with two major spines down the middle and smaller spines around the lateral edges. Paraclytia nephropiformis (von Schlu¨ter 1879) Figure 4d–f, Tables 1 and 2. Material examined: BGR sent one specimen (BGR X273), comprising cephalothorax, abdomen and a claw, figured by Mertin (1941: pl. 2, Fig. 8). P. valashtensis is most similar to P. nephropiformis (von Schlu¨ter 1879), being of comparable carapace length, having thoracic carinae of similar form and in similar positions, and an elongate tubercle in the field above hepatic groove b1 that is level with the branchial carina. However, as discussed above, the carapace of P. valashtensis is relatively deep in lateral view when compared with that of P. nephropiformis. Mertin (1941) describes the intermediate carina on P. nephropiformis as having five spines behind the postcervical groove, while P. valashtensis has only four elongate spines on the carina itself, with smaller, rounded tubercles behind it on the posterior border. The abdominal sculpture of the two lobsters is similar, with longitudinal peaks or carinae on front and rear fields of the terga, although those on the rear field of P. nephropiformis are described as being separate from the posterior edge, rather than coming directly out of the thickened edge as is the case with at least the first two terga of the Iranian species. The ornamentation of the pleura is also different on the two species. The Iranian fossil has pleura
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Fig. 5 Distribution of Paraclytia localities in the Late Cretaceous. Palaeogeographic base map from Scotese (2001a, b) with modifications
with two strong spines running down the centre and a gentle thickening of the lateral edges, which is developed into small spines in places; the remainder of the pleuron surface is smooth and unornamented. P. nephropiformis has much spinier pleura, which typically have several small to medium-sized spines scattered over their surface, in addition to two strong central spines and small spines around the pleuron edges. Palaeobiogeography The four previously known Paraclytia species are all from Late Cretaceous rocks in a fairly restricted area of central Europe, in Germany and the neighbouring Czech Republic (Fig. 5): P. nephropica is known from the Pla¨ner (lightly coloured Upper Cretaceous marl) of the White Mountain (Weisser Berg) near Prague, Czech Republic. Age: Turonian (Mertin’s 1941 specimen) to Senonian (=Coniacian to Maastrichtian Stages; Fritsch 1887; Glaessner 1929).
P. boetticheri is known from Halberstadt and Quedlinburg, in north central Germany. Age: Coniacian. P. westfalica is known from Henrichenburg and Recklinghausen, in west central Germany. Age: Lower Senonian (=Coniacian/Santonian Stages?) P. nephropiformis is known from Braunschweig and Broitzem, north central Germany. Age: Senonian (=Coniacian to Maastrichtian Stages). The discovery of a species of Paraclytia in northern Iran represents a significant southeastward expansion of the geographical range of the genus (Fig. 5). However, it is perhaps not surprising that Paraclytia was able to spread through the shallow epicontinental sea that covered large areas of western Eurasia, the Middle East and northern Africa at that time, and given suitable depositional conditions, further finds of the genus might be expected to increase its distribution further. Acknowledgments Leonid Popov, National Museum Wales, is thanked for bringing the specimen of P. valashtensis to LMEM’s attention. Norbert Hauschke, Institut fu¨r Geologische Wissenschaften
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430 und Geiseltalmuseum der Universita¨t Halle, provided casts of specimens of P. boetticheri and P. westfalica. Jan Sklena´rˇ, National Museum, Prague, provided casts and photographs of specimens of P. nephropica. Angela Ehling, Bundesanstalt fu¨r Geowissenschaften und Rohstaffe, Hannover, loaned a specimen of P. nephropiformis. Ronald Winkler, Museum fu¨r Mineralogie und Geologie, Dresden, provided photographs of a specimen of P. nephropica. Dale Tshudy, Edinboro University of Pennsylvania, is thanked for providing extracts from his thesis and paper reprints relating to Paraclytia and Metanephrops. Robert Owens, National Museum Wales, gave very useful comments on drafts of this paper.
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