Deep-water fossorial shrimps from the Oligocene Kiscell Clay of Hungary: Taxonomy and palaeoecology

We describe deep-water ghost shrimp assemblages from the otherwise well known Oligocene Kiscell Clay in Hungary. The described fossorial shrimps (Decapoda: Callianassidae and Ctenochelidae) include: Ctenocheles rupeliensis (younger synonym Callianassa nuda) and Lepidophthalmus crateriferus (younger synonym Callianassa brevimanus). The fossil material of the former species is assigned to Ctenocheles based on the morphology of the major cheliped, particularly the pectinate fingers, bulbous propodus, cup-shaped carpus and elongated merus. Lepidophthalmus crateriferus from the Oligocene of Hungary is the first unequivocal fossil record of the genus, which is distinguished in the fossil record on the basis of the presence of a meral blade and meral hook on the major cheliped. Lepidophthalmus is today known exclusively from shallow-water environments. The finding of a deep-water fossil representative of Lepidophthalmus therefore appears to be a reverse of the common pattern of groups shifting environments from onshore to offshore over geological time, as seen in many taxa. The presence of Lepidophthalmus crateriferus comb. nov. in the Kiscell Clay therefore suggests different ecological requirements for at least some populations of this genus in the geological past

Comment on the letter of the Society of Vertebrate Paleontology (SVP) dated April 21, 2020 regarding “Fossils from conflict zones and reproducibility of fossil‑based scientific data”: Myanmar amber

Non peer reviewe

Revision of the Miocene shrimp Callianassa kerepesiensis Müller, 1976 (Malacostraca, Decapoda), with a description of a new species

Hyžný, Matúš (2020): Revision of the Miocene shrimp Callianassa kerepesiensis Müller, 1976 (Malacostraca, Decapoda), with a description of a new species. Zootaxa 4801 (2): 363-373, DOI: 10.11646/zootaxa.4801.2.1

Callianassa Leach 1814

Genus <i>Callianassa</i> Leach, 1814 <p> Type species: <i>Cancer Astacus subterraneus</i> Montagu, 1808, by original designation.</p> <p> <b>Remarks.</b> The taxonomic history of the genus is convoluted; for various concepts see e.g. Manning & Felder (1991), Sakai (1999, 2005, 2011), Ngoc-Ho (2003), and Poore <i>et al</i>. (2019). For a long time, it has been the common catch-all genus for many extant species whose systematic position was uncertain (Poore <i>et al</i>. 2019). In a similar way, throughout the palaeontological literature <i>Callianassa</i> is used as a collective name; for more details a reference is made for Hyžný & Klompmaker (2015). In his major work on middle Miocene (Badenian) decapods, Müller (1984) was well aware of difficulties of taxonomic evaluation of callianassid shrimps and used “ <i>Callianassa</i> ” with a notion of its unclear status. Herein, the genus is used in its revised concept of Poore <i>et al</i>. (2019).</p>Published as part of <i>Hyžný, Matúš, 2020, Revision of the Miocene shrimp Callianassa kerepesiensis Müller, 1976 (Malacostraca, Decapoda), with a description of a new species, pp. 363-373 in Zootaxa 4801 (2)</i> on page 367, DOI: 10.11646/zootaxa.4801.2.10, <a href="http://zenodo.org/record/3900380">http://zenodo.org/record/3900380</a&gt

Calliax de Saint Laurent 1973

Genus Calliax de Saint Laurent, 1973 Type species. Callianassa (Callichirus) lobata de Gaillande & Lagardère, 1966, by original designation and monotypy. Remarks. The genus Calliax de Saint Laurent, 1973, has rather a complex taxonomic history (Hyžný & Gašparič 2014; Ngoc-Ho 2014). Here the concept of the genus presented by Ngoc-Ho (2003, 2014) and Poore et al. (2019) is followed rather than that of Sakai (2011). It has been argued that at least for some genera the morphology of the major P1 propodus can be diagnostic on the genus level (Hyžný 2012; Hyžný & Müller 2012). In this respect, the genus Calliax is identifiable based on the following characters (emended from Hyžný & Gašparič 2014): 1) major propodus rectangular, usually longer than high; 2) fixed finger shorter than manus, with a (double) ridge accompanied by a furrow and/or depression extending onto manus; 3) fixed finger with subdistal tooth on the occlusal margin. It should be mentioned that the ridge is well-developed mainly in larger specimens, whereas in smaller individuals it is faint or not present. Even more diagnostic for Calliax is the morphology of the minor chela (Hyžný & Gašparič 2014; Poore et al. 2019), which, unfortunately, is not observable in the present material. In this respect, Poore et al. (2019: 126) argued that: “the wide gap between the fingers of the minor cheliped, with an intermediate tooth, immediately defines species of Calliax.”Published as part of Hyžný, Matúš, 2020, Revision of the Miocene shrimp Callianassa kerepesiensis Müller, 1976 (Malacostraca, Decapoda), with a description of a new species, pp. 363-373 in Zootaxa 4801 (2) on pages 364-365, DOI: 10.11646/zootaxa.4801.2.10, http://zenodo.org/record/390038

First occurrence of "Prosopidae" s.l. (Crustacea: Decapoda: Brachyura) and other findings of crustaceans in the Upper Jurassic limestones of the Pieniny Klippen Belt

Tyt. z nagłówka.Bibliografia s.63.Dostępny również w formie drukowanej.KEYWORDS: Pieniny Klippen Belt, limestones, Upper Jurassic. SŁOWA KLUCZOWE: wapienie, pieniński pas skałkowy, górna jura

Diversity and distribution patterns of the Oligocene and Miocene decapod crustaceans (Crustacea: Malacostraca) of the Western and Central Paratethys

Decapod associations have been significant components of marine habitats throughout the Cenozoic when the major diversification of the group occurred. In this respect, the circum-Mediterranean area is of particular interest due to its complex palaeogeographic history. During the Oligo-Miocene, it was divided in two major areas, Mediterranean and Paratethys. Decapod crustaceans from the Paratethys Sea have been reported in the literature since the 19th century, but only recent research advances allow evaluation of the diversity and distribution patterns of the group. Altogether 176 species-level taxa have been identified from the Oligocene and Miocene of the Western and Central Paratethys. Using the three-dimensional NMDS analysis, the composition of decapod crustacean faunas of the Paratethys shows significant differences through time. The Ottnangian and Karpatian decapod associations were similar to each other both taxonomically and in the mode of preservation, and they differed taxonomically from the Badenian ones. The Early Badenian assemblages also differed taxonomically from the Late Badenian ones. The time factor, including speciation, immigration from other provinces and/or (local or global) extinction, can explain temporal differences among assemblages within the same environment. High decapod diversity during the Badenian was correlated with the presence of reefal settings. The Badenian was the time with the highest decapod diversity, which can, however, be a consequence of undersampling of other time slices. Whereas the Ottnangian and Karpatian decapod assemblages are preserved virtually exclusively in the siliciclastic “Schlier”-type facies that originated in non-reefal offshore environments, carbonate sedimentation and the presence of reefal environments during the Badenian in the Central Paratethys promoted thriving of more diverse reef-associated assemblages. In general, Paratethyan decapods exhibited homogeneous distribution during the Oligo-Miocene among the basins in the Paratethys. Based on the co-occurrence of certain decapod species, migration between the Paratethys and the North Sea during the Early Miocene probably occurred via the Rhine Graben. At larger spatial scales, our results suggest that the circum-Mediterranean marine decapod taxa migrated in an easterly direction during the Oligocene and/or Miocene, establishing present-day decapod communities in the Indo-West Pacific

Systematics, phylogeny, and taphonomy of ghost shrimps (Decapoda): a perspective from the fossil record

Ghost shrimps of Callianassidae and Ctenochelidae are soft-bodied, usually heterochelous decapods representing major bioturbators of muddy and sandy (sub)marine substrates. Ghost shrimps have a robust fossil record spanning from the Early Cretaceous (~ 133 Ma) to the Holocene and their remains are present in most assemblages of Cenozoic decapod crustaceans. Their taxonomic interpretation is in flux, mainly because the generic assignment is hindered by their insufficient preservation and disagreement in the biological classification. Furthermore, numerous taxa are incorrectly classified within the catch-all taxon Callianassa. To show the historical patterns in describing fossil ghost shrimps and to evaluate taphonomic aspects influencing the attribution of ghost shrimp remains to higher level taxa, a database of all fossil species treated at some time as belonging to the group has been compiled: 250 / 274 species are considered valid ghost shrimp taxa herein. More than half of these taxa (160 species, 58.4%) are known only from distal cheliped elements, i.e., dactylus and / or propodus, due to the more calcified cuticle locally. Rarely, ghost shrimps are preserved in situ in burrows or in direct association with them, and several previously unpublished occurrences are reported herein. For generic assignment, fossil material should be compared to living species because many of them have modern relatives. Heterochely, intraspecific variation, ontogenetic changes and sexual dimorphism are all factors that have to be taken into account when working with fossil ghost shrimps. Distal elements are usually more variable than proximal ones. Preliminary results suggest that the ghost shrimp clade emerged not before the Hauterivian (~ 133 Ma). The divergence of Ctenochelidae and Paracalliacinae is estimated to occur within the interval of Hauterivian to Albian (133–100 Ma). Callichirinae and Eucalliacinae likely diverged later during the Late Cretaceous (100–66 Ma), whereas Callianassinae did not appear before the Eocene (56 Ma)

Calliax de Saint Laurent 1973

Genus Calliax de Saint Laurent, 1973 Type species. — Callianassa (Callichirus) lobata de Gaillande & Lagardère, 1966. Extant species included. — Three species (including one referred species but not formally named): Calliax doerjesti Sakai, 1999 (Figs 3A–B); Calliax lobata (de Gaillande & Lagardère, 1966) (Figs 3C–D); Calliax sp. sensu Taviani et al. (2013). Fossil species included.– Calliax michelottii (A. Milne Edwards, 1860) comb. nov. More fossil occurrences in open nomenclature are recognized (see Table 1). Diagnosis. Carapace lacking dorsal oval; rostrum short, with blunt tip, rostral spine absent. Pleonal segment 2 longest, no lateral tufts of setae on segments 3–5. Telson slightly wider than long, lateral margin curved, posterior margin straight or slightly convex. Eyestalk about twice as long as wide, slightly flattened dorso-ventrally; cornea small, weakly pigmented. A1 peduncle shorter than that of A2. Mxp1 epipod tapering anteriorly. Mxp2 with small, leaf-like epipod. Mxp3 subpediform (sensu Ngoc-Ho 2003), propodus and dactylus rounded, exopod absent. P1 unequal, dissimilar. Major P1 propodus rectangular, usually longer than high, fixed finger shorter than manus, with a double ridge accompanied by a furrow extending onto manus and parallel to the lower margin of propodus. Fixed finger as long as dactylus in major P1, shorter than dactylus in minor P1, with wide proximal gap and large triangular proximal tooth on cutting edge. Major P1 carpus shorter than high, distinctly shorter than propodus. Major P1 merus longer than high, keeled, lower margin armed with small spines. P3 with small proximal heel on propodus, P5 subchelate. Paired arthrobranch on Mxp3 and P1–4. Male and female Plp1 uniramous male and female Plp2 biramous, all lacking appendix interna, male Plp2 with appendix masculina overreaching endopod. Plp3–5 biramous, foliaceous, appendix interna finger-like in both sexes. Uropodal endopod and exopod slightly longer than telson, with rounded posterior margin; exopod with dorsal plate terminating in short distal setal row [emended from Ngoc-Ho (2003: 489) with characters on major P1]. Remarks on the taxonomy. Calliax has a complex taxonomic history. The genus was erected by de Saint Laurent (1973) with Callianassa lobata de Gaillande & Lagardère, 1966, as the type species. Since then the concept of the genus has been changed several times (cf. Manning & Felder 1991; Sakai 1999, 2005, 2011; Ngoc- Ho 2003; Hyžný 2012; see also Dworschak 2007). Here the view of Ngoc-Ho (2003) and Sakai (2011) is adopted, and thus, only two formally described extant species are recognized. Discussion on distinguishing Calliax from related taxa based on soft-part morphology was provided by Ngoc-Ho (2003) and will not be repeated here. When dealing with chelipeds the two known extant species of Calliax can be characterized by unequal and dissimilar chelae, from which the minor one has „fixed finger shorter than and separated from the dactylus by a wide gap, bearing a large triangular proximal tooth (Ngoc-Ho 2003: 490)“. This morphology approaches a subchelate cheliped state. Comparison of the illustrated major P1 propodus of C. lobata (de Gaillande & Lagardère 1966: fig. 2a; de Saint Laurent & Božić 1976: fig. 23; Ngoc-Ho 2003: fig. 17D), C. doerjesti (Sakai 1999: figs. 28, 29b) and Calliax sp. (Taviani et al. 2013: fig. 8) clearly shows consistency in its general shape, i.e. propodus is rectangular and usually longer than high and on its lateral surface the fixed finger possesses two ridges accompanied by furrow (or furrows) parallel to the lower margin of propodus and extending onto manus. The ridges are visible especially when viewing under low angle light (Fig. 2C). There are several distinct setal pores (accompanied by tubercles) arranged obliquely across the lateral surface of propodus. In Calliax the major P1 carpus is always much shorter than manus, with rounded proximo-lower margin (Fig. 3). The merus is longer than high with a distinct meral keel and its lower margin is usually armed with small spines. The above mentioned combination of the characters of minor chela and major propodus, carpus and merus is unique for Calliax; thus, the genus can be identified on the basis of chelipeds alone. The number of spines on the lower margin of P1 merus may vary between respective members of Calliax and may help in distinguishing taxa at the species level, although possible variation has not been studied in detail yet. Regarding the number of meral spines, there are discrepancies in the literature. Sakai (1999: 114) in the description of C. doerjesti mentioned that the lower margin of the merus was “armed with three interspaced denticles”. One of the figures (Sakai 1999: fig. 29b) indeed shows three small spines, however, in the other one (Sakai 1999: fig. 28) depicting the same specimen (holotype) the merus is armed with seven spines (Fig. 3a). Ngoc-Ho (2003: fig. 17D; note that the published figure depicts the right major chela, whereas the caption refers to it as the left one) figured the holotype (male) of C. lobata with seven spines on the merus and de Saint Laurent & Božić (1976: fig. 23a) figured a female specimen of C. lobata also with seven spines. Calliax cf. C. lobata, examined and figured herein (Figs 2, 3E–F), possesses only four blunt spines, presumably mirroring its small size (Fig. 4). Remarks on the fossil record. Articulated chelipeds are relatively sparse in the fossil state and often only isolated propodi are at hand. In this respect, the major P1 propodus of Calliax is distinct enough to be differentiated from all other ghost shrimp genera. It must be stressed, however, that the more cheliped elements are found, the more secure assignment at the genus level can be provided. The best preserved and most numerous remains of Calliax in the fossil record belong to species originally described as Callianassa michelottii (Figs 5–10). It is discussed in detail below. Feldmann et al. (2005) reported several isolated cheliped elements from the Miocene of the Navidad Formation of Chile as Callianassoidea sp. 1. Although the authors stated that it does not resemble any callianassoid genus (Feldmann et al. 2005: 431), the figured material (Feldmann et al. 2005: fig. 2A) exhibits striking similarities with Calliax as discussed herein. Interestingly, Callianassa szobensis Müller, 1984, which is herein considered a junior subjective synonym of C. michelottii (see below) and hence a member of Calliax, is mentioned by Feldmann et al. (2005) as similar to their Callianassoidea sp. 1. The same locality also yielded another specimen which has been identified as Callichirus sp. The figured propodus (Feldmann et al. 2005: fig. 2A) shows a relatively short manus; however, the fixed finger with ridges and a furrow indicates its affinities to Callianassoidea sp. 1 (Feldmann et al. 2005: fig. 2D). Both specimens are treated here as Calliax sp. 1. Feldmann et al. (2011) reported fragmented material from the Miocene of Tierra del Fuego (Argentina) as “Cheliped Form B” of indeterminate callianassoid. As already noted by Hyžný & Hudáčková (2012: 13), the minor chela exhibits remarkable similarities to Calliax, (Feldmann et al. 2011: fig. 5E) showing a fixed finger shorter than the dactylus and separated from it by a wide gap with a proximal tooth (cf. Ngoc-Ho 2003: 490). The major P1 propodus (Feldmann et al. 2011: fig. 5B), however, does not possess the ridges on the fixed finger. It is fairly likely that the two specimens do not belong to the same taxon, as they were not found associated with each other. For the purposes of this contribution only the minor chela is referred to here as Calliax sp. 2. Charbonnier et al. (2013) reported a single near-complete propodus from the Paleocene of Pakistan identified as a minor chela of Calliax. Indeed, the specimen shows all features typical for minor chelae of the genus (Charbonnier et al. 2013: fig. 2) as discussed above. This occurrence is considered the oldest confirmed fossil record of the genus, treated here as Calliax sp. 3. Callianassa whiteavesi Woodward, 1896 from the Campanian of Canada (Woodward 1896; Feldmann & McPherson 1980; Schweitzer et al. 2003) was assigned to Calliax by Schweitzer et al. (2003). The material is rich and sufficiently preserved to reconstruct both chelipeds (Feldmann & McPherson 1980). The species differs markedly from any Calliax species. It does not possess the typically shaped minor cheliped as discussed above, nor has it parallel ridges on the base of the fixed finger. Moreover, some specimens exhibit a rather deep dactylus, a character not observed in Calliax. As a result, the species is excluded from Calliax herein. Until the type material is restudied we suggest to keep the species under Callianassa sensu lato. Swen et al. (2001) reported a single fragmentary right propodus from the Maastrichtian of the Netherlands as “ Calliax ? sp.”. The material is too fragmentary for resolving its generic status. The oblique development of the ridge at the base of fixed finger (Swen et al. 2001: fig. 5.3), however, points to closer affinities to Eucalliax or Calliaxina rather than Calliax. Van Bakel et al. (2006) listed in a table of Cenozoic decapods from Belgium the presence of Calliax in the Miocene strata. The material was recently described as a new member of the family Axiidae (Fraaije et al. 2011). Occurrence and distribution. Paleocene–Holocene. Two formally described extant species are known from West Atlantic (Florida) and Mediterranean (Sakai 2011). Based on the reports discussed above (Feldmann et al. 2005, 2011), the geographical distribution of the genus was much wider during the Miocene than today, and the genus was apparently also present in the East Pacific (see below). All occurrences are reviewed in Table 1.Published as part of Hyžný, Matúš & Gašparič, Rok, 2014, Ghost shrimp Calliax de Saint Laurent, 1973 (Decapoda: Axiidea: Callianassidae) in the fossil record: systematics, palaeoecology and palaeobiogeography, pp. 37-57 in Zootaxa 3821 (1) on pages 42-45, DOI: 10.11646/zootaxa.3821.1.3, http://zenodo.org/record/491991

Eucalliax Manning & Felder 1991

Genus Eucalliax Manning & Felder, 1991 Type species. Callianassa quadracuta Biffar, 1970. Remarks on taxonomy. The taxonomy of Eucalliax is rather complex. The genus was established by Manning & Felder (1991) for several species previously assigned to the genus Calliax de Saint Laurent, 1973. They noted that chelipeds are equal and similar in Eucalliax, whereas Calliax possesses unequal chelipeds. Ngoc-Ho (2003) provided a detailed account on the differences between the two genera both in soft-part and hard-part morphology. She considered chelipeds in Eucalliax subequal and similar, whereas in Calliax, chelipeds are unequal, and the minor has "fixed finger shorter than and separated from the dactylus by a wide gap, bearing a large triangular proximal tooth" (Ngoc-Ho 2003: 490). She also erected a new genus Calliaxina Ngoc-Ho, 2003 for three species previously treated as Calliax: C. novaebritanniae (Borradaile, 1900), C. punica (de Saint Laurent & Manning, 1982) and C. sakaii (de Saint Laurent & Le Loeuff, 1979). For Calliaxina, subequal, similar and laterally compressed first pereiopods are typical, whereas in Calliax, they are also lateraly compressed, but unequal and dissimilar (Ngoc-Ho 2003). Sakai (1999, 2005) recognized Eucalliax and Calliaxina as junior synonyms of Calliax. Later, he (Sakai 2011) recognized all of them as valid, but his concept of Eucalliax and Calliaxina differs markedly from that of Ngoc-Ho (2003). He restricted Eucalliax to Callianassa quadracuta Biffar, 1970 only, and for Calliaxina listed C. aequimana (Baker, 1907), C. bulimba (Poore & Griffin, 1979), C. jonesi (Heard, 1989), C. mcilhennyi (Felder & Manning, 1994) and C. panglaoensis (Dworschak, 2006) besides C. novaebritanniae, C. punica and C. sakaii. We follow Ngoc-Ho (2003) rather than Sakai (2011) in recognizing only three species of Calliaxina. We consider the rest of above mentioned species as members of Eucalliax, thus following works of Manning & Felder (1991), Felder & Manning (1994) and Dworschak (2005, 2006). In this respect the material presented herein with its subequal and similar chelipeds falls within the range of the genus Eucalliax. It possesses massive chelipeds which is in contrast to Calliaxina sensu Ngoc-Ho (2003) with laterally compressed chelipeds. Remarks on the fossil record. All three Eucalliacinae genera discussed above have been identified in the fossil record. Concerning distinguishing Calliax and Eucalliax from each other in the fossil state, Schweitzer et al. (2003: 12) mentioned the nature of the lower margin of merus, which is serrated in Calliax and without serration in Eucalliax. Unfortunately, this does not seem to be consistent. For instance Biffar (1970: 42) mentioned presence of denticulation in C. quadracuta which is the type species of Eucalliax. In E. pseudorakosensis comb. nov. as recognized herein, the denticulation is also present, although only in large specimens (Fig. 10 E). The fossil record of Calliax is obscure. Callianassa whiteavesi Woodward, 1896 from the Campanian of British Columbia and Alberta, Canada was reassigned to Calliax by Schweitzer et al. (2003). Recently Feldmann et al. (2011) reported a few claw fragments as "Cheliped Form B" of indeterminate callianassoid. The material shows remarkable similarities to the genus Calliax as defined by Ngoc-Ho (2003). Interestingly, a minor chela is also preserved (Feldmann et al. 2011: fig. 5 E) exhibiting fixed finger shorter than dactylus and separated from it by a wide gap with a proximal tooth, a combination of characters which has been so far documented in Calliax only (Ngoc-Ho 2003). Swen et al. (2001) reported a single fragmentary right propodus from the Maastrichtian of the Netherlands classified as Calliax ? sp. It is very difficult to assign this specimen to any genus of the subfamily Eucalliacinae without evidence of both chelipeds. Van Bakel et al. (2006) listed in a table of Cenozoic decapods from Belgium the presence of Calliax nov. sp. in the Miocene strata. The systematic placement of the material has recently been reconsidered to represent a new member of the family Axiidae (Fraaije et al. 2011). Eucalliax was reported from the Eocene, Miocene and Pliocene of Japan: E. yoshihiroi Karasawa, 1992; E. yatsuoensis (Karasawa, 1993); and E. miyazakiensis Karasawa, 1993 respectively. Kato (1996) reported several specimens classified as Eucalliax sp. from the Miocene of Japan. These specimens, however, possess tubercles on the lateral surface of propodus, which is highly unusual for the genus. Moreover, they were associated with Callianopsis spp., for which such tuberculation is quite typical. Kato (1996: 507) stated that Eucalliax sp. is distinguishable from Callianopsis spp. "by the absence of a large, triangular tooth on the proximal part of the fixed finger, and having a remarkably small fixed finger on the left chela". These characters can not be considered as important for generic assignment (see Hyžný & Schlögl 2011: 326). In fact, the presence and absence of a triangular tooth on the fixed finger may mirror sexual dimorphism in Callianopsis de Saint Laurent, 1973 as already documented by Schweitzer Hopkins & Feldmann (1997) and Hyžný & Schlögl (2011). Kato (1996) did not state why he had placed the specimens in Eucalliax. Several occurrences of the genus have been reported also from the Eocene of Italy. Beschin et al. (2002) described Eucalliax vicetina Beschin, Busulini, De Angeli & Tessier, 2002, based on virtually entire major and minor chelipeds. Finally Beschin et al. (2009) reported a single incomplete propodus referred to Eucalliax sp. from the Lower Eocene of Italy. Its morphology, however, strongly suggests the assignment to ctenochelid genus Ctenocheles Kishinouye, 1926. The presence of Ctenocheles sereaensis Beschin, De Angeli & Zorzin, 2009 in the same strata reported in the same paper may confirm the here presented opinion. It should be noted that virtually none of the above mentioned Calliax and Eucalliax occurrences have been reexamined with respect to the work by Ngoc-Ho (2003). If following the genus concept of Eucalliacinae taxa presented by Ngoc-Ho (2003), all the fossil material assigned at one time to these genera should be revised to confirm or reject their current generic assignment. Calliaxina has been identified in the fossil record only recently (Hyžný, in prep.). Exhaustive treatment on the distinction between Eucalliax and Calliaxina in the fossil record is beyond the scope of the paper and will be published elsewhere (Hyžný, in prep.). Eucalliax pseudorakosensis (L ő renthey in L ő renthey & Beurlen, 1929) new combination (Figs 7–11) Calianassa pseudorakosensis Lőrenthey in Lőrenthey & Beurlen, 1929: 69, pl. 2 figs. 16–18. Callianassa pseudorakosiensis. — Glaessner, 1929: 88; Schweitzer et al., 2010: 36. Callianassa cf. pseudorakosensis. — Bachmayer, 1953: 241; Müller, 1998: 10. Callianassa cf. jahringensis Glaessner, 1928: 166, pl. 3 figs. 2, 2 a; Glaessner, 1929: 83; Müller, 1984: 53. " Callianassa " pseudorakosensis. — Müller, 1976: 507; Hyžný, 2011 a: 41, fig. 4 A, B, Table 1, 2.; Hyžný, 2011 b: 167, Table 1. ‘ Callianassa ’ pseudorakosensis. — Müller, 1984: 52, pl. 3 figs. 4–5, pl. 4 figs. 1-6, pl. 5 figs. 1–4. Non Callianassa pseudorakosensis. — Radwański & Wysocka, 2004: 390, pl. 9 fig. 2. Emended diagnosis. Heterochelous eucalliacine ghost shrimp with chelipeds without pronounced tuberculation. Merus of major cheliped ovoid with lower margin possesssing faint denticles; carpus about as long as high, squarish or rhomboidal in shape, unarmed with keeled upper and lower margins. Palm massive, subequal in length and height with keeled upper and lower margins; fixed finger with or without triangular blunt tooth; distal margin of propodus finely serrated; weak unarmed excavation extending from below the articulation with the dactylus forming a weak keel. Dactylus heavy, curved, quadrate on the cross section proximally, armed on cutting edge with blunt tooth proximally and keel forming a distal tooth. Minor cheliped smaller in size than major, dissimilar in shape, carpus longer than high, triangular in shape, upper margin keeled and arcuate; propodus higher than long, upper and lower margins distinctly keeled; fixed finger high, cutting edge slightly convex distally, dactylus slender, curved, unarmed. Emended description. First pereiopods with major and minor cheliped strongly developed, slightly unequal in size, dissimilar in shape of propodus and dentition of fingers; major cheliped located on either right or left side of body. Two different morphotypes were identified in the nature of major propodus; morphotype with triangular tooth positioned at the base of fixed finger (Fig. 7 A) and morphotype without tooth (Fig. 7 B). Major cheliped massive and strongly calcified; ischium slender (Fig. 10 C), upper margin sinuous, lower margin with row of tiny denticles; merus ovoid, longer than high (L/H = 1.8–2.0), highest at midlength, lower margin straight or slightly convex, with tiny denticles, upper margin slightly convex, smooth, lateral surface with keel positioned around the middle (e.g. Figs 10 E, G, H); carpus about as long as high, highest distally, about as long as merus, squarish or rhomboidal in shape (Figs. 7 A, 10), unarmed, lower margin arcuate, upper and lower margins keeled (Figs 8 I, O), terminating distally in blunt corners, margins of proximo-lower corner forming almost right angle; propodus heavy, palm approximately as long as high, lateral surfaces smooth, upper and lower margins keeled, keel of lower bent slightly inward, becoming ill-defined beyond midlength and absent on fixed finger; fixed finger thick, prehensile margin unarmed (morphotype without tooth) or armed with one well separated tooth in midlength (morphotype with tooth), serrated with tiny denticles distally, otherwise unarmed, terminating in rounded tip, tip bent slightly upward; distal margin of propodus finely serrated; weak unarmed excavation extending from below the articulation with the dactylus to below the tooth on mesial face, thus forming a faint keel; dactylus heavy, curved, quadrate on the cross section proximally (Fig. 8 Q), armed on cutting edge with blunt tooth proximally (Fig. 8 J) and keel forming a distal tooth distally pointing downward near the tip of dactylus (e.g. Figs 7 C, 8 F), tip sharp and slightly hooked. Minor cheliped smaller in size than major, dissimilar in shape, carpus longer than high, triangular in shape (Figs 7 D, 9 E, F), upper margin keeled and arcuate; articulation between carpus and propodus more than 90 º; propodus higher than long (Fig. 9), upper and lower margins distinctly keeled; fixed finger high, cutting edge slightly convex distally, the tip narrowing abruptly, pointed and bent slightly upward; dactylus slender, curved, unarmed. Variations. There are two distinct forms, occurring on both right and left chelae, most probably due to a dimorphism. One morphotype has a triangular tooth at the base of the fixed finger, the other one has no such tooth; this dimorphism was already recognized by Lőrenthey & Beurlen (1929) and Müller (1984). A quick scan of published figures showed that at least in some taxa, such dimorphism may mirror sex. A toothed fixed finger seems to be present mostly in females, whereas a morphotype without the tooth is more typical for males as can be documented in the following examples: a distinctly toothed fixed finger has been figured in female specimens of E. aequimana (Poore & Griffin 1979: fig. 12 d), E. kensleyi Dworschak, 2005 (Dworschak 2005: figs. 3, 4), and E. mcilhennyi (Felder & Manning 1994: fig. 1); a morphotype without a toothed fixed finger has been figured in male specimens of E. aequimana (Poore & Griffin 1979: fig. 12 l), E. bulimba (Poore & Griffin 1979: figs. 21 d, e), E. jonesi (Heard 1989: figs. 1, 4 b; Felder & Manning 1994: fig. 5 e) and E. mcilhennyi (Felder & Manning 1994: figs. 2 b, c). On the other hand, no such pattern has been observed in E. cearaensis Rodrigues & Manning, 1992, and E. panglaoensis. Interestingly, sexual dimorphism has been observed in E. panglaoensis, although in different pattern. In this species chelipeds of females and small males are almost equal in size, whereas in large males they become slightly unequal (Dworschak 2006: 356, fig. 7); the triangular tooth is present in major chelae in both sexes. Concerning E. cearaensis, it is questionable whether it is representative for the genus; Sakai (2011) erected for this species a new genus Eucalliaxiopsis. We do not explain unequivocally the variability in the nature of major propodus of E. pseudorakosensis comb. nov. as a consequence of sexual dimorphism. It should, however, be mentioned that the same pattern of dimorphs have been recognized in the ctenochelid genus Callianopsis as mirroring sexual dimorphism; thus, the presence of a tooth at the base of the fixed finger is indicative of females, whereas males have no such tooth (Schweitzer Hopkins & Feldmann 1997; Hyžný & Schlögl 2011). In this context it is worth mentioning that recent molecular analysis by Felder & Robles (2009) has shown a rather close phylogenetic relationship between Ctenochelidae Manning & Felder, 1991 and Eucalliacinae. Variations in the nature of the dactylus have also been observed. Usually smaller specimens have the distal tooth on the occlusal margin of dactylus rather blunt, or even not developed at all, however, in that case a swollen area in the place is present. In larger specimens the tooth becomes sharper and more distinct (Fig. 7 C). The same can be said about the keel on the occlusal margin of dactylus itself, which is very well pronounced in larger specimens. This type of variation can be correlated with size/age of the individual. Material examined. FI M. 20 (holotype, right major propodus, morphotype with tooth, figured in Lőrenthey & Beurlen 1929: pl. 2, fig. 16), FI M. 2347 (right major propodus, morphotype with tooth); KGP-MH DH-016–KGP- MH DH-040, KGP-MH DH-040, KGP-MH DH-043, KGP-MH DH-044, KGP-MH DH-047, KGP-MH DH-051, KGP-MH DH-053, KGP-MH DH-054, KGP-MH DH-057, KGP-MH DH-059, KGP-MH DH-062, KGP-MH DH- 0 63, KGP-MH DH-069, KGP-MH DH-069; M. 86.530 (collective number); SNM Z- 7943 (collective number), SNM Z- 16419 (collective number), SNM Z- 16433 (collective number), SNM Z- 21373; SNM Z- 37554 – SNM Z- 37569; PAL 2011.22–PAL 2011.28; PCMH-004–PCMH-007, PCRB DH-017– PCRB DH-028. For measurements and all the details see Table 2. merus carpus propodus dactylus continued next page Occurrence. The species is very common in the sediments of the Middle Miocene age of the countries once forming an area of the Central Paratethys Sea. Up to now it has been reported from the late Early ('Karpatian') and Middle Miocene ('Badenian') of Hungary (Lőrenthey & Beurlen 1929; Müller 1984), Romania (Lőrenthey & Beurlen 1929; Müller 1984), Austria (Glaessner 1928; Müller 1984, 1998), and Slovakia (Hyžný 2011 a, b, this contribution). The species often occurs in large numbers as exemplified in studied material from Dúbravská hlavica and published material from Hungarian localities Rákos and Mátraverebély-Szentkút (Müller 1984), and from the Romanian locality Minişu de Sus (Felménes) (Lőrenthey & Beurlen 1929; Müller 1984). Remarks. Eucalliax pseudorakosensis comb. nov. is very easily distinguishable from all similar fossil forms. Its propodus is heavy and when viewed distally, it is very robust in its upper half (in place of articulation with dactylus), whereas the lower part is more depressed, partly also due to the arcuate and keeled lower margin curved inward. Moreover, it has a rounded cross section of the fixed finger, whereas similar Middle Miocene forms, as " Callianassa " chalmasii Brocchi, 1883 and " Callianassa " rakosiensis Lőrenthey, 1897, are oval (Lőrenthey in Lőrenthey & Beurlen 1929: 68). When dealing with more complete chelipeds, E. pseudorakosensis comb. nov. can be characterized by a squarish or rhomboidal carpus, and a dactylus armed with a distal tooth. These characters distinguish the species from all extant members of the genus, as well as from all relative fossil taxa. Radwański & Wysocka (2004) reported from the Middle Miocene of Poland a single chela attributed to Callianassa pseudorakosensis associated with trace fossils of the ichnogenus Ophiomorpha Lundgren, 1891. The morphology of the specimen is, however, distinctly different from E. pseudorakosensis comb. nov. The preserved propodus with articulated dactylus is somewhat fractured and slightly deformed (Radwański & Wysocka 2004: fig. 1.2); however, the general morphology can be inferred. The upper margin seems to taper proximally unlike Eucalliax pseudorakosensis comb. nov. for which the opposite is true. The keel on the fixed finger is strongly developed; in E. pseudorakosensis comb. nov., it is developed only weakly. The dactylus is completely unlike that of E. pseudorakosensis comb. nov. in being very high and lacking the distinctive tooth positioned distally on the occlusal margin. Moreover, the specimen seems to be rather flat (laterally compressed sensu Ngoc-Ho, 2003) and not massive which is quite typical for E. pseudorakosensis comb. nov., and therefore it resembles members of the genus Calliaxina Ngoc-Ho, 2003. As the specimen has been examined only via photographs, we are hesitant to discuss its affinities further, although it is clear that it is not conspecific and possibly even not congeneric with E. pseudorakosensis comb. nov. Personal observation is needed to definitely state its systematic affinity.Published as part of Hyžný, Matúš & Hudáčková, Natália, 2012, Redescription of two ghost shrimps (Decapoda: Axiidea: Callianassidae) from the Middle Miocene of the Central Paratethys: systematics, intraspecific variation, and in situ preservation, pp. 1-25 in Zootaxa 3210 on pages 12-21, DOI: 10.5281/zenodo.20948