Van Straelen Research Articles

Pyrenicola (Crustacea: Decapoda: Brachyura), new genus for Litoricola macrodactyla (Van Straelen, 1924) and Litoricola macrodactyla pyrenaica (Artal and Vía, 1989), and remarks on Coeloma (Milne-Edwards, 1865)

A new genus, Pyrenicola, is proposed to accommodate Xanthilites macrodactylus Van Straelen, 1924 from the Thanetian of Haute Garonne (France), and X. macrodactylus pyrenaicus Artal and Vía, 1989 from the Ypresian of Aragon (Spain), as well as clarify their relationships with the morphologically close Litoricola Woodward, 1873, where both are currently placed, and with Coeloma A. Milne-Edwards, 1865. As a result, Litoricola is herein revalidated as an available genus, different from Coeloma, of which it has frequently been considered either a subgenus or a synonym. Also, the subspecies Xanthilites macrodactylus pyrenaicus is elevated to full species rank as Pyrenicola pyrenaica n. comb. The familial placement of Pyrenicola n. gen., Litoricola and particularly of Coeloma, currently placed within Polybiinae Paulson, 1875 (Portunoidea Rafinesque, 1815) is revised. Consequently, a new placement of the three genera within Geryonidae Colosi, 1923, the most basal portunoid crabs, is herein proposed.

An Aptian sponge-associated decapod crustacean assemblage from Cal Cassanyes (Catalonia, north-east Iberian Peninsula): Taxonomy and palaeoecological implications

A highly diverse decapod crustacean fauna is described from the classic Aptian outcrop of Cal Cassanyes (Castellet i la Gornal) in Catalonia. Although decapod crustaceans are a minor component of the rich invertebrate assemblages at that locality, the just over fifty specimens collected comprise sixteen taxa assignable to the Macrura, Anomura and Brachyura. Of these, the last-named are the most prominent group, comprising eleven species, representing seven families, inclusive of one representative of the Eubrachyura. On the basis of this material, two new genera and five new species are erected, namely Pagurus? garrafensis sp. nov., Garrafosopon gen. nov. angustus (Wright and Collins, 1972) comb. nov., Vectis blesai sp. nov., Mesodromilites prietoi sp. nov., Necrocarcinus mariae sp. nov. and Iberodorippe vinea gen. nov., sp. nov. In addition, Hoploparia sp., an indeterminate axiid and one paguroid, as well as one indeterminate galatheoid are recorded here. Material of Distefania incerta (Bell, 1863), the commonest species at the study site by far, of Goniodromites laevis (Van Straelen, 1940) and of Etyxanthosia fossa (Wright and Collins, 1972) represents the first Aptian and stratigraphically oldest records for these taxa. Added to this list are also Eodromites sp., Paranecrocarcinus? sp. and Pseudonecrocarcinus? sp. The high decapod crustacean diversity at Cal Cassanyes establishes this locality as the richest Aptian assemblage from the Iberian Peninsula, but also one of the richest in the world. The faunal assemblages here are dominated by sponges, and the varied composition of the decapod crustacean faunas can be linked to upwelling currents which provided abundant nutrients. In fact, the establishment of sponge communities played a crucial role in activating the food chain and functioned similarly to a patch reef, creating a relatively sheltered environment that facilitated the colonisation of other invertebrate communities, including decapod crustaceans. The latter occupied various trophic levels as both primary and secondary consumers. Current knowledge of Early Cretaceous decapod crustaceans is scant and hinders a thorough palaeobiogeographical analysis. The present study emphasises the challenges surrounding the identification of endemic taxa, thus impacting our understanding of decapod crustacean palaeobiogeography of the late Early Cretaceous.

New genera and species of glaessneropsid crabs from the Lower and Middle Jurassic of France and Germany-Austria, and reconsolidation of Charassocarcinus Van Straelen, 1925

A new genus, Meroncarcinus, and two new species, M. boursicoti and Verrucarcinus marsae, are described from Callovian (Middle Jurassic) deposits of Calvados and Maine-et-Loire, France. New material of the type species of the genus Verrucarcinus, V. torosus, is examined, which improves our understanding of the peculiar morphology of this group of crabs. A new genus and species, Vilsercarcinus keuppi, is recognised from Lower-Middle Jurassic strata of Germany-Austria. Charassocarcinus, a Lower-Middle Jurassic crustacean genus of doubtful taxonomic affinity, is revived and here assigned to the Glaessneropsidae. All of this material forms the basis for a re-examination of the Glaessneropsidae, and an enhanced diagnosis is compiled. The morphology of Glaessneropsidae, one of the oldest known brachyuran families, is discussed; its complex orbital structure is remarkable for such an ancient group of crab and raises questions about its relationship with the basal brachyuran group Homolodromioidea. A solid support for a suprafamilial rank for the Glaessneropsidae is lacking.

Presence of Zanthopsis M’Coy, 1849 (Crustacea: Decapoda: Brachyura) in the Early Eocene of Iran, and comments on the different species and/or morphotypes and their palaeobiogeography

In the present work, we report the discovery of several carapaces of Zanthopsis sp. from the Lower Eocene of Central Iran, which represent the easternmost record of the genus. In addition, we discuss on the similarities of the different species and/or morphotypes of the genus, and conclude that the European species could be ascribed to the “Zanthopsis leachii complex”, until future works determine the validity of the species therein contained. In this sense, Zanthopsis jacobi Van Straelen, 1924, in agreement with Artal and Vía (1988), is herein considered a junior synonymous of Z. dufouri (H. Milne Edwards in d’Archiac, 1850). The presence of Zanthopsis in the lower Eocene of Iran suggests homogeneity of the brachyuran fauna on both sides of the Tethys Realm.

A synthesis of the evolutionary history of erymoid lobsters (Crustacea, Decapoda, Erymoidea)

A synthesis of our current knowledge of erymoid lobsters is presented. The superfamily Erymoidea includes two families, Erymidae Van Straelen, 1925 and Enoploclytiidae Devillez, Charbonnier & Barriel, 2019, together encompassing 81 species within six genera. Our examination of the palaeobiodiversity of this group and its evolution has revealed some variations through the Mesozoic with three important peaks, at the boundaries of: 1) Lower-Middle Jurassic; 2) Middle-Upper Jurassic; and 3) Lower-Upper Cretaceous. Whereas the origin of the first peak remains poorly known, the two others coincide with major modifications of the environment: the development of the European Jurassic carbonate platforms and the development of the European Chalk Sea and the partial flooding of North America during the mid- and Late Cretaceous. In addition to a notable peak of diversity, the Cretaceous is an important time interval in the evolutionary history of erymoids because the Early Cretaceous represented a long period of relatively low diversity and during the Late Cretaceous a strong decline of erymoid faunas is observed in Europe. However, the erymoids had already attained a worldwide distribution during the Early Cretaceous with occurrences in all oceans of the time. The analysis of the palaeobiogeographic distribution of these lobsters suggests the presence of important migratory paths, which probably favoured their spread and faunal exchanges between different areas across the globe.

Spanish type specimens in fossil invertebrate collection of Museo Nacional de Ciencias Naturales of Madrid, Spain

The main objective of the present paper is to communicate, to the paleontological community the type material of fossil invertebrates at the Museo Nacional de Ciencias Naturales. Most of this type material belongs to historic collections that were recovered after the retrieval and study of 70% of the fossil invertebrates material, and includes type specimens from W.Kilian, ].Vilanova y Piera, J. Lambert and V. van Straelen amongst other well-known naturalists.

Systematic Revision and Palaeobiology of Emplastron edwardsi (Van Straelen, 1928) gen. et comb. nov. (Crustacea, Decapoda, Astacidae) Entombed within Travertine, from Sézanne, France

Crayfish are rare in the fossil record and therefore it is important to investigate each occurrence in detail. The only known fossil crayfish from France, Astacus edwardsi Van Straelen, 1928, is known from a replica made by pouring plaster of Paris inside the holotype (subsequently destroyed), an external mould extracted from a travertine cavity from the Thanetian of Sézanne. An evaluation of the taxonomic name, A. edwardsi, is provided; A. edwardsi is considered valid in accordance with ICZN rulings. It possesses atypical features for all other astacid genera, thus Emplastron gen. nov. is erected. Emplastron edwardsi gen. et comb. nov. inhabited a warm climate with calm waters, abundant food sources, and an ample supply of calcium carbonate: so much so that it is surprising that it is the only recovered specimen. Despite apparent North American faunal and floral affinities in the vicinity, E. edwardsi is more closely related to European crayfishes than it is to American ones.

A new lithophylacid crab (Crustacea, Decapoda, Portunoidea) from the Late Cretaceous (early Maastrichtian) of Cuba

Icriobranchiocarcinus rodas Vega n. sp., is recorded from lower Maastrichtian (Upper Cretaceous) Arroyo Grande Formation near the town of Rodas (Central Cuba). I. rodas Vega n. sp. represents additional evidence of paleobiogeographic affinities between Chiapas (SE Mexico) and Cuba, during the Late Cretaceous. The genus Icriobranchiocarcinus Vega, 2018 in Vega et al., 2018 was erected from the type species Icriobranchiocarcinus tzutzu Vega, 2018 from the lower Maastrichtian Ocozocoautla Forma-tion (Chiapas). I. rodas Vega, n. sp. preserves details of ventral morphology as well as more details of chelipeds not reported in I. tzutzu, adding to the morphology of the genus. Icriobranchiocarcinus belong to a family (Lythophylacidae Van Straelen, 1936) that became extinct worldwide during the K/Pg event.

Earth science collections of the Centre Grégoire Fournier (Maredsous) with comments on Middle Devonian–Carboniferous brachiopods and trilobites from southern Belgium

Although the Centre Grégoire Fournier of the Maredsous Abbey is especially famous for the fossils and minerals from the Carboniferous (Viséan) ‘black marble’ of Denée, a marine conservation-Lagerstätte, its palaeontological collections likewise include some types and illustrated specimens of invertebrates (cystoids, goniatites, ostracods, trilobites) and fishes from the Ordovician, Devonian and Carboniferous of Belgium. These specimens are discussed and/or illustrated as is the case of the fragments of two Belgian meteorites (Lesves and Tourinnes-la-Grosse chondrites) that are part of the CGF mineralogical and petrological collections. Moreover, the type material of 30 species and subspecies of Upper Devonian–Pennsylvanian linguliformean and rhynchonelliformean brachiopods (described by de Koninck (1847), J. Fraipont (1888a), Ch. Fraipont (1908), Demanet (1923, 1934), Demanet (in Demanet & Van Straelen, 1938), and Grimm (1998)) and that of two Middle–Upper Devonian species of trilobites (Stainier, 1887; Richter & Richter, 1933), almost all from the Namur–Dinant Basin (southern Belgium), are re-investigated and/or fully figured for the first time in order to facilitate future taxonomic revision. The obscure Tournaisian genus Anomianella de Ryckholt (1851) is rejected from the bivalves and transferred to the brachiopods (Craniida). It is probably related to Petrocrania Raymond, 1911. The lectotype (hereby selected) of Orthis latissima M‘Coy, 1844 and that of Producta corrugata M‘Coy, 1844, both from the Viséan of Ireland, are photographically illustrated (for the first time for the former). The lectotype of Productus murchisonianus de Koninck, 1847 from the Upper Palaeozoic of Tasmania (Australia) is also designated.

Early Cretaceous (late Barremian) Crustacea from Puebla, Mexico

The oldest record of fossil decapods, associated to reefs from Mexico is reported. Six species of Anomala and brachyuran crustaceans, collected from limestones of the upper Barremian Zapotitlán Formation, Puebla, Mexico: Luisogalathea cretacea (Stenzel, 1945); Eomunidopsis limonitica (Stenzel, 1945); Paragalathea ruizi Van Straelen, 1940; Goniodromites laevis (Van Straelen, 1940); Distefania sp.; and Cretamaja klompmakeri González-León and Moreno-Bedmar, new species, are reported. This assemblage bears similarities with crustaceans reported from the upper Albian of the Pawpaw Shale of Texas and to other reef crustaceans from the Late Jurassic and Early Cretaceous of Europe. This is first record in the Americas for some genera. The here reported specimens are found associated to sponges, corals, mollusks and bryozoans, that suggest a shallow marine reef environment for this region of Central Mexico during late Barremian times. All of the specimens represent isolated dorsal carapaces, some with evidence of little transport.

Review of the Early and Middle Jurassic erymid lobsters (Crustacea: Decapoda)

Erymid lobsters (Crustacea, Decapoda, Erymidae) are an important component of Mesozoic crustacean faunas in Europe, especially during the Jurassic. The 29 species reported from the Early and Middle Jurassic are the oldest found in Western Europe and North America, and constitute an important part of the evolutionary history of these lobsters. After the review presented here, 24 species are maintained within the genera Eryma Meyer, 1840 (7 species), Palaeastacus Bell, 1850 (5 species), Pustulina Quenstedt, 1858 (2 species) and Stenodactylina Beurlen, 1928 (9 species). All these species, with the exception of Eryma ventrosum (Meyer, 1835), have a new description and the diagnoses of the genera Eryma, Palaeastacus and Stenodactylina are emended. Four species are transferred to another genus: Palaeastacus numismalis (Oppel, 1862) n. comb., Palaeastacus foersteri (Feldmann, 1979) n. comb. and Stenodactylina guisei (Wright, 1881) were previously assigned to Eryma, and Stenodactylina spinosa (Étallon, 1861) n. comb. was previously assigned to Palaeastacus. Our study shows that Stenodactylina was the most diversified genus in Early – Middle Jurassic, but the fossils of Eryma are more common. Furthermore, Eryma compressum (Eudes-Deslongchamps, 1842) is the emblematic species of Erymidae Van Straelen, 1925 during the end of Early Jurassic and Middle Jurassic in Western Europe (Toarcian – Bathonian). This species includes now Eryma bedeltum (Quenstedt, 1858) in its synonymy. The genus Pustulina is very rare and the specimens show some characteristics on their carapace recalling other erymid genera (an almost sinuous hepatic groove for example), that are absent in more recent species. Finally, we point out that only E. compressum, P. foersteri and Stenodactylina walkerae (Feldmann and Haggart, 2008) are reported outside Europe.

Review and additions to the Maastrichtian (Late Cretaceous) crustacea from Chiapas, Mexico

The Maastrichtian crustacean fauna from Chiapas is illustrated and reviewed with reports of new taxa, including the marine isopod Palaega sp., described for the first time from the lower Maastrichtian Ocozocoautla Formation, represented by molted remains of the posterior carapace. New specimens and a neotype of the raninoid Vegaranina precocia (Feldmann et al., 1996) are illustrated and compared with specimens of Vegaranina sp. from the late Maastrichtian of France. New specimens of Carcineretes woolacotti Withers, 1922, from the late Maastrichtian of Chiapas are reported and recognized as the sole species of the genus, distributed in the upper Maastrichtian lithostratigraphic units from the Caribbean; the new specimens are compared with others of the same species and age from the Guinea Corn Formation in Jamaica and the Barton Creek Formation in Belize. Icriobranchiocarcinus tzutzu Vega new genus and species, is reported as a new member of the Icriocarcininae Števcic, 2005, a diverse subfamily of lithophylacid crabs, along with illustrations and discussion on Branchiocarcinus flectus (Rathbun, 1926) (Maastrichtian, Gulf and Atlantic plains), Icriocarcinus xestos Bishop, 1988 (Maastrichtian, Pacific of California and Baja California), and Lithophylax trigeri A. Milne-Edwards and Brocchi, 1879 (Cenomanian, France), in order to confirm that all of these species belong to the Lithophylacidae Van Straelen, 1936, but to different subfamilies (Lithophylacinae and Icriocarcininae) and genera. Parazanthopsis meyapaquensis Vega, Feldmann, García-Barrera, Filkorn, Pimentel & Avendaño, 2001, is compared with Palaeoxanthopsis cretacea (Rathbun, 1902) (late Maastrichtian, Brazil), and with Palaeoxantho libertiensis Bishop, 1986 (late Maastrichtian, Mississippi), in order to illustrate differences and confirm that these species belong to separate genera. Megaxantho zoque Vega, Feldmann, García-Barrera, Filkorn, Pimentel & Avendaño, 2001 is reviewed and compared to Menippe frescoensis Remy, 1960 (early Eocene, Senegal) and Menippe mercenaria (Say, 1818) (living species, Gulf of Mexico), to confirm the late Maastrichtian species from Chiapas should be recognized as Menippe zoque new combination, representing the oldest confirmed species for the genus. The age and lithostratigraphic units for all these Maastrichtian crustaceans from Chiapas is reviewed and corrected, based on recent data reported by other scientists, who defined the litho and biostratigraphy with macro and microfossils reported from the study area, nearby Tuxtla Gutiérrez and Ocozocoautla, Chiapas. A correlation between the late Maastrichtian lithostratigraphic units of Chiapas and those from the Caribbean region is confirmed, and their distribution in turn of the Chicxulub impact area in the Yucatán Peninsula is illustrated.

First Jurassic occurence of Enoploclytia M’Coy, 1849 (Crustacea: Decapoda: Erymidae)

Among the Erymidae Van Straelen, 1925, known as early as the Late Permian (Changhsingian) and widespread in the Jurassic, the genus Enoploclytia M’Coy, 1849 seems to have a late appearance because of its lack before the Cretaceous. Until now, the oldest representative was E. augustobonae Devillez, Charbonnier, Hyžný and Leroy, 2016 from the Early Cretaceous (Barremian) of the eastern Paris basin (France). However, a new fossil collected in Normandy (France), showing the typical carapace groove pattern of Enoploclytia, attests the presence of the genus in the Late Jurassic (Oxfordian).

A new look at the shrimps (Crustacea, Decapoda, Penaeoidea) from the Middle Jurassic La Voulte-sur-Rhône Lagerstätte

The Middle Jurassic La Voulte-sur-Rhône Lagerstätte yields fossils with remarkable morphological details. Those depict a highly diversified bathyal palaeocommunity dominated by arthropods. Amongst them, shrimps are very abundant. We hereby redescribe the two most abundant species of shrimps (Dendrobranchiata, Penaeoidea), Aeger brevirostris Van Straelen, 1923 (Aegeridae), and Archeosolenocera straeleni Carriol & Riou, 1991 (Solenoceridae). This leads us to consider Antrimpos secretaniae Carriol & Riou, 1991 as a junior synonym of A. straeleni. The latter is the only fossil representative of its family.

Late Devonian (Frasnian) phyllopod and phyllocarid crustacean shields from Belgium reinterpreted as ammonoid anaptychi.

The taxonomic affinities of fossils from the Frasnian succession of Belgium previously described as phyllopod and phyllocarid crustacean shields are discussed. The rediscovery of the holotype of Ellipsocaris dewalquei, the type species of the genus Ellipsocaris Woodward in Dewalque, 1882, allows to end the discussion on the taxonomic assignation of the genus Ellipsocaris. It is removed from the phyllopod crustaceans as interpreted originally and considered here as an ammonoid anaptychus. Furthermore, it is considered to be a junior synonym of the genus Sidetes Giebel, 1847. Similarly, Van Straelen's (1933) lower to middle Frasnian record Spathiocaris chagrinensis Ruedemann, 1916, is also an ammonoid anaptychus. Although ammonoids can be relatively frequent in some Frasnian horizons of Belgium, anaptychi remain particularly scarce and the attribution to the present material to peculiar ammonoid species is not possible.

Review of the Late Cretaceous erymid lobsters (Crustacea: Decapoda) from the Western Tethys

The Erymidae Van Straelen, 1925 had a worldwide distribution during the Jurassic and the Cretaceous. Twenty-seven species among four genera were reported in the Late Cretaceous, but confusions in diagnoses have led to wrong generic identifications of many erymid species. In the light of recent clarifications of the diagnoses of erymid genera, the Late Cretaceous species are here reviewed. We recognize thirteen of them including three European species which benefit of new descriptions: Palaeastacus sussexiensis (Mantell, 1824), Enoploclytia leachi (Mantell, 1822) and Enoploclytia seitzi Glaessner, 1932. Furthermore, a comparison of the Late Cretaceous erymid fauna with that from the Early Cretaceous emphasizes some changes. A decrease in diversity on genus and species level is noted with the absence of Eryma Meyer, 1840 in the Late Cretaceous and the predominance of Enoploclytia M’Coy, 1849 (including almost half of the species). Despite the scarcity of the fossil record, our palaeobiogeographic interpretations led us to propose hypotheses about the provenance of North American populations in the end of Early Cretaceous and in Late Cretaceous: (1) their supposed absence since the Callovian (Jurassic) is due to collecting and/or reporting bias or (2) they were the result of migrations of European populations. Moreover, the report of a chela assigned to Stenodactylina cf. armata (Secrétan, 1964) in France confirms the existence of migration routes between European and Malagasy faunas during the Late Cretaceous.

Mecochirus Germar (Decapoda: Glypheoidea) in the Lower Cretaceous of Queensland

JELL, P.A., WOODS, J.T. & COOK, A.G., May 2017. Mecochirus Germar (Decapoda: Glypheoidea) in the Lower Cretaceous of Queensland. Alcheringa 41, 514–523 ISSN 0311-5518.Three new species of glypheoid decapod crustaceans, Mecochirus mcclymontorum, M. bartholomaii and M. lanceolatus, are described from the late Aptian of the Eromanga, Carpentaria and Maryborough basins, respectively. The first two occur in the Doncaster Member of the Wallumbilla Formation and the last in the Maryborough Formation. This is the first record of Mecochirus Germar, 1827 or the Mecochiridae Van Straelen, 1925 in Australia and one of only a few Cretaceous occurrences of this largely Jurassic genus.Peter A. Jell [amjell@bigpond.com], Jack T. Woods and Alex G. Cook [alex.cook@y7mail.com], School of Earth Sciences, The University of Queensland, St Lucia Queensland 4072, Australia.

A preliminary review of the fossil species of Ranina Lamarck, 1801 (Decapoda, Brachyura, Raninidae), with systematic remarks

The systematics of the fossil representatives of Ranina Lamark, 1810, has been discussed by several authors in the last century, showing some problematics above all due to the lack of a close diagnosis of the type species (R. ranina) and to the scarce number of well-preserved type series of each fossil species. However, based upon a close comparison among the type series of each species, authors’ original descriptions, and the main diagnostic characters of Ranina, this preliminary review finds that twelve species have to be considered as doubtful species within Ranina, as follows: ?Ranina americana Withers, 1924, ?R. berglundi Squires & Demetrion, 1992, ?R. bouilleana A. Milne Edwards, 1872, ?R. brevispina Lőrenthey, 1898, ?R. granulosa A. Milne Edwards, 1872, ?R. griesbachi Noetling, 1897, ?R. haszlinskyi Reuss, 1859, ?R. libyca (Van Straelen, 1935), ?R. molengraaffi Van Straelen, 1924, ?R. oblonga (von Münster, 1840), ?R. ornata De Angeli & Beschin, 2011, and ?R. speciosa (von Münster, 1840). Four species have to be considered as Ranina nomina dubia, as follows: Ranina elegans Rathbun, 1945, R. hirsuta (Schafhäutl, 1863), R. lamiensis Rathbun, 1945, and R. tejoniana Rathbun, 1926. Ranina bavarica Ebert, 1887, R. fabri Schafhäutl, 1863, and R. helii Schafhäutl, 1863, have to be assigned to Lophoranina Fabiani, 1910. Ranina cuspidata Guppy, 1909, has to be assigned to Calappa Weber, 1795 (Calappidae De Haan, 1833). Finally, R. burleighensis Holland in Holland & Cvancara, 1958, has to be considered as doubtful species within Decapoda.

On the sighted ancestry of blindness - exceptionally preserved eyes of Mesozoic polychelidan lobsters.

BackgroundModern representatives of Polychelida (Polychelidae) are considered to be entirely blind and have largely reduced eyes, possibly as an adaptation to deep-sea environments. Fossil species of Polychelida, however, appear to have well-developed compound eyes preserved as anterior bulges with distinct sculpturation.MethodsWe documented the shapes and sizes of eyes and ommatidia based upon exceptionally preserved fossil polychelidans from Binton (Hettangian, United-Kingdom), Osteno (Sinemurian, Italy), Posidonia Shale (Toarcian, Germany), La Voulte-sur-Rhône (Callovian, France), and Solnhofen-type plattenkalks (Kimmeridgian-Tithonian, Germany). For purposes of comparison, sizes of the eyes of several other polychelidans without preserved ommatidia were documented. Sizes of ommatidia and eyes were statistically compared against carapace length, taxonomic group, and outcrop.ResultsNine species possess eyes with square facets; Rosenfeldia oppeli (Woodward, 1866), however, displays hexagonal facets. The sizes of eyes and ommatidia are a function of carapace length. No significant differences were discerned between polychelidans from different outcrops; Eryonidae, however, have significantly smaller eyes than other groups.DiscussionFossil eyes bearing square facets are similar to the reflective superposition eyes found in many extant decapods. As such, they are the earliest example of superposition eyes. As reflective superposition is considered plesiomorphic for Reptantia, this optic type was probably retained in Polychelida. The two smallest specimens, a Palaeopentacheles roettenbacheri (Münster, 1839) and a Hellerocaris falloti (Van Straelen, 1923), are interpreted as juveniles. Both possess square-shaped facets, a typical post-larval feature. The eye morphology of these small specimens, which are far smaller than many extant eryoneicus larvae, suggests that Jurassic polychelidans did not develop via giant eryoneicus larvae. In contrast, another species we examined, Rosenfeldia oppeli (Woodward, 1866), did not possess square-shaped facets, but rather hexagonal ones, which suggests that this species did not possess reflective superposition eyes. The hexagonal facets may indicate either another type of superposition eye (refractive or parabolic superposition), or an apposition eye. As decapod larvae possess apposition eyes with hexagonal facets, it is most parsimonious to consider eyes of R. oppeli as apposition eyes evolved through paedomorphic heterochrony.ConclusionPolychelidan probably originally had reflective superposition. R. oppeli, however, probably gained apposition eyes through paedomorphosis.

Two new species of Cenomanocarcinus Van Straelen, 1936 (Decapoda: Brachyura: Paleocorystoidea) from the Lower and Middle Cretaceous of Texas, USA, with remarks on intraspecific variation in Cenomanocarcinus

Two new species of Cenomanocarcinus Van Straelen, 1936 (Decapoda: Brachyura: Paleocorystoidea) from the Lower and Middle Cretaceous of Texas, USA, with remarks on intraspecific variation in Cenomanocarcinus