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Thylacocephala are among the most problematic of arthropod fossils. Various authors have allied them with all manner of crustacean groups, including branchiopods, cirripedes, remipedes, and malacostracans. They have a very apomorphic body plan often marked by hypertrophy of the compound eyes, three pairs of large raptorial subchelate limbs, eight sets of well-developed phyllobranch gills, and from 8 to at least 16 posterior trunk somites bearing paddle-like limbs. They have been thought of as a distinct class composed of two orders, Concavicarida and Conchyliocarida, but membership within the orders varies according to authors, and no familial divisions have been proposed within the orders until now. This lack of taxonomic structure inhibits organization of available information concerning the paleoecology, paleogeography, and phylogenetic relationships of thylacocephalans. A working hypothesis for the higher taxonomy within the class is proposed here. This entails a redefinition of the two orders, and recognition of seven families, five of them new: Austriocarididae Glaessner, 1931, Clausocarididae Arduini, 1992 (new status), Concavicarididae n. fam., Dollocarididae, n. fam., Microcarididae n. fam., Ostenocarididae n. fam. and Protozoeidae n. fam.

Leaiais a special genus of extinct “conchostracan” branchiopods; its soft parts have not been known until now. The leaiid specimens with soft bodies reported in the present paper came from two localities: the Upper Carboniferous Canso Group of New Brunswick, Canada, and the Permian Mount Glossopteris Formation of the Ohio Range, Holick Mountains, Antarctica. They include head, biramous antennae, mandible, shell gland, male claspers, and digestive tube. These parts together fully demonstrate that the leaiid clam shrimp indeed should be attributed to the crustaceans, instead of Mollusca. Based on the ribbed valves and structure of soft parts it should be placed in the branchiopodan Diplostraca. We believe that this group, which went extinct at the end of the Permian, is quite different from those of Laevicaudata, Spinicaudata, and Cyclestheriida. Hence, it should have its own higher taxon, Leaiina. The well-developed and sharply pointed head, delicate and short biramous antennae, in concert with the radial ribs on the valves probably indicate a burrowing in-faunal habit.

The study of biogeography was once a pillar of evolution science. Both Darwin and especially Wallace found great inspiration from the consideration of animal distributions. However, what is to happen to this discipline in a time of global trade, mass movement of people and goods, and the resulting globalization of the planet’s biota? Can we still hope to delve into the fine points of past geography as it affected animal and plant evolution? Maybe we can, but only with careful study of life forms that suffer minimal affects – at present – from globalization, viz., marginal faunas of quite inaccessible environments. Two examples taken from syncarid crustaceans illustrate this point. Bathynellacea provide insight into ancient patterns of distribution and possible modes of evolution of that group. Modern Anaspididae yield some surprising information concerning the timing of evolutionary events.

As a result of cladistic analyses involving fossil hoplocaridans, the palaeostomatopods emerge as paraphyletic. Consequently, the genus Archaeocaris requires a separate family, erected herein. A partir des resultats d'analyses cladistiques incluant les formes hoplocarides fossiles, les palaeostomatopodes emergent comme paraphyletiques. En consequence le genre Archaeocaris necessite la creation d'une famille separee, ce que nous faisonsici.

The suborder Ingolfiellidea currently consists of 39 named species. An historical overview is presented and phylogenetic and biogeographic analyses are made. The result of the phylogenetic analysis suggests the definition of two new genera within an African freshwater group, namely Paraleleupia n. gen. and Proleleupia n. gen. Re-examination of a supposedly Italian relict species, Metaingolfiella mirabilis, with the aid of SEM techniques reveals a half-fusion of the head region with the first pereionite. The issue of the function of the ‘eyelobe’ is addressed and an explanation presented after examining with SEM such lobes in different species. Furthermore, additional descriptions are given based on the type-material of Metaingolfiella mirabilis, Trogloleleupia eggerti, Trogloleleupia leleupi, Ingolfiella littoralis, I. tabularis, I. margaritae, I. quadridentata, and I. abyssi. An attempt to relate the geographic distribution and ecological characteristics to the phylogeny of the Ingolfiellidea results in a paleogeographic scenario that points to a freshwater subterranean origin for the group that dates from at least Triassic times.

Three new species of malacostracans are described from North America in the Upper Mississippian Into Formation of Arkansas, and the Pennsylvanian Eudora Shale of southeastern Kansas. These appear to be the oldest fossils attributed to the Cumacea and are only the third collection of fossil cumaceans anywhere to be described. Previously depicted forms occur in the Permian and Jurassic of Europe. We herein double the number of described fossil cumacean species and suggest some necessary adjustments to the higher taxonomy of the group to accommodate apomorphic features of the fossil and Recent forms.

A cladistic analysis based on external morphology was carried out on 60 taxa of decapod crustaceans. An analysis with unordered characters and one with ordered characters were both in agreement regarding the major relationships. The ordered analysis gave better resolution of more advanced clades, while the unordered analysis gave better resolution of more basal clades. None of the traditional groups Palinura, Anomura, and Macrura is monophyletic. A new classie cation of decapod crustaceans is proposed. Homarida and Astacida are closely related, as shown by the unique process on the ischium of their e rst pereiopods. Glypheoidea forms the sister group to Astacura, within an enlarged Astacidea. Achelata is the sister group to Meiura (Anomala + Brachyura) in a new clade, Eurysternalia, characterized by a unique antennular morphology and by the eponymous wide sternum of its members. Thalassinida emerge as the sister group to Eurysternalia, in a new clade, Sterropoda, characterized by fusion of the e rst segments of the thoracic limbs. The fractostern is interpreted to be a eureptant feature, and a possible burrowing habitus is posited for the ancestral Eureptantia.

A cladistic analysis of Neoglyphea inopinata Forest & de Saint Laurent, 1975, clearly reveals that it possesses both of the diagnostic apomorphies for the fractosternalian Reptantia, the fractured or articulated sternum between the seventh and eighth thoracic somites, and the tripartite secula. Furthermore, there is a distinctive epistome form that is otherwise seen only in the freshwater Astacida. These features have implications for the eventual modification of the higher taxonomy and our ideas concerning the evolution of Reptantia. Une analyse cladistique de Neoglyphea inopinata Forest & de Saint Laurent, 1975, revele clairement que cette derniere possede les deux apomorphies diagnostiques pour les Reptantia Fractosternalia, le sternum articule entre le septieme et le huitieme segments thoraciques, et la secula tripartite. De plus, il y a une forme particuliere de l'epistome qui n'est presente, par ailleurs que chez les Astacida d'eaux douces. Ces caracteristiques ont des implications pour une eventuelle modification de la taxonomie de rang superieur et pour nos idees concernant l'evolution des Reptantia.

The analysis of consecutive ontogenetic stages, or events, introduces a new class of data to phylogenetic systematics that are distinctly different from traditional morphological characters and molecular sequence data. Ontogenetic event sequences are distinguished by varying degrees of both a collective and linear type of dependence and, therefore, violate the criterion of character independence. We applied different methods of phylogenetic reconstruction to ontogenetic data including maximum parsimony and distance (cluster) analyses. Two different data sets were investigated: (1) four simulated ontogenies with defined phylogenies of six hypothetical taxa, and (2) a set of “real” data comprising sequences of 29 ontogenetic events from 11 vertebrate taxa. We confirm that heterochronic event sequences do contain a phylogenetic signal. However, based on our results we argue that maximum parsimony is a biased method to analyze such developmental sequence data. Ontogenetic events require a special analytical algorithm that would not neglect instances of chronological (horizontal) dependence of this type of data. One coding method, “event-pairing”, appeared to fulfill this requirement in the vertebrate analyses. However, to accurately analyze ontogenetic sequence data, a more sophisticated coding method and algorithm are needed, for example, measuring distances of dependent events.

Structures, reminiscent of the lattice organs in thecostracan crustaceans, are described from the carapace cuticle of Cretaceous thylacocephalans. The new lattice organ like structures occur in pairs along the dorsal midline. While these have a similar outline to true lattice organs, they seem to lack pores and do not occur in the highly apomorphic pattern found in thecostracans. These discrepancies do not easily support earlier ideas of a position of the thylacocephalans within the thecostracans. The significance of the possible lattice organs for inferring a relationship between thylacocephalans and thecostracans is discussed.

Recent discoveries in the field of developmental genetics have lead to the resurrection of the old idea, first proposed in the early 19th century, that the dorso-ventral axis of deuterostomes, such as vertebrates, has been inverted during the course of evolution from that noted in protostomes, i.e., what in deuterostomes dorsal, is in protostomes ventral. However, while attractive its simplicity, such a suggestion ignores the real events of embryogenesis. During the onset of gastrulation in deuterostomes as well as in protostomes a blastopore is formed with exactly the same embryonic, antero-posterior/dorso-ventral polarity. Subsequent differences in the patterns or morphogenetic movement in gastrulation result in a spatial inversion of this developmental architecture in the adult body plans of protostomes versus deuterostomes. In deuterostomes, the initial anterior posterior axis is extended more or less evenly while the blastopore remains located posteriorly. In protostomes, such as annelids and gastropods, the growth of the original antero-posterior or animal-vegetal axis is extremely uneven and almost exclusively limited to cells of the embryonic dorsal side. This is coupled with the cells of the original ventral side of the embryo in part moving into the inside of the embryo, and in part moving into what had spatially been the embryonic lateral and more dorsal position. Because of this uneven migration, the embryonic ventral side of the developing larva is not extended and the initial antero-posterior axis is bent, with the blastopore moving into an animal-vegetal position. What were originally dorsal cells move to a ventral position. This fully explains the conservation of developmental gene expression patterns as resulting from a shift of initially dorsally specified cells to a secondarily ventral position.

[A new genus and species of fossil decapod, Jilinocaris chinensis, is described from the Late Cretaceous of northern China. Although incompletely preserved, enough anatomy is visible to suggest that this species represents the first fossil example of the Stenopodidea and is tentatively assigned to the family Spongicolidae. Es wird eine neue Gattung und Art eines fossilen Dekapoden, Jilinocaris chinensis, aus der Unterkreide Nordchinas beschrieben. Obwohl nicht vollstandig erhalten, reichen die auswertbaren anatomischen Daten aus, um diese Art als erstes fossiles Exemplar der Stenopodidea vorzuschlagen und vorerst der Familie Spongicolidae zuzuordnen., A new genus and species of fossil decapod, Jilinocaris chinensis, is described from the Late Cretaceous of northern China. Although incompletely preserved, enough anatomy is visible to suggest that this species represents the first fossil example of the Stenopodidea and is tentatively assigned to the family Spongicolidae. Es wird eine neue Gattung und Art eines fossilen Dekapoden, Jilinocaris chinensis, aus der Unterkreide Nordchinas beschrieben. Obwohl nicht vollstandig erhalten, reichen die auswertbaren anatomischen Daten aus, um diese Art als erstes fossiles Exemplar der Stenopodidea vorzuschlagen und vorerst der Familie Spongicolidae zuzuordnen.]

A new monotypic genus of Spelaeogriphacea is described from the Upper Jurassic of Liaoning Province, north-east China. This new genus and species brings the number of known spelaeogriphacean taxa to four, the others being two recent forms from Brazil and South Africa, and one from the Carboniferous of eastern Canada. The new Chinese form is morphologically(and phylogenetically) very similar to the recent spelaeogriphaceans, suggesting that the body plan seenin the recent Spelaeogriphacea was achieved relatively early in the history of the group. A cladistic analysis of this and several other peracaridan orders indicates that the Spelaeogriphacea may be a paraphyletic group. This suggests that much work remains to be done with respect to the taxonomy and phylogenetic relationships among the peracaridan taxa.

The palaeostomatopod crustacean Bairdops beargulchensis Schram & Horner, 1978 (Malacostraca, Hoplocarida) from the Mississippian Bear Gulch Limestone is now seen as a taxonomic composite that arose from the confusion of specimens of two distinct hoplocarid species. These species are herein described as the palaeostomatopod Bairdops beargulchensis Schram & Horner, 1978 and a new species of archaeostomatopod, Tyrannophontes acanthocercus. Tyrannophontes acanthocercus is quite distinct from the Pennsylvanian archaeostomatopod T. Theridion from the Essex fauna (Mazon Creek), with which it was originally compared. Bairdops beargulchensis is very similar to the Mississippian palaeostomatopod, B. elegans, from the Scottish Glencartholm fauna. A previously proposed synonymy of B. beargulchensis with T. theridion is therefore rejected. A preliminary restudy of the archaeostomatopods T. Theridion and Gorgonophontes peleron, and the palaeostomatopods Perimecturus Rapax and P. parki, reveals some newly recognized characters of those taxa and suggests some novel interpretations of hoplocarid evolution. A cladistic phylogenetic analysis of the Hoplocarida including the Paleozoic forms resolves the higher level relationships of the hoplocarids (palaeostomatopods, archaeostomatopods, aeschronectids, and unipeltatans).

Lawrence (1999, 2004) has laid out a very interesting point of view concerning the phylogenetic affinities of Collembola and invites debate. The point of his argu ments is that Collembola have been misplaced amongst the apterygote Hexapoda, and he maintains that they rather should be allied with the Amphipoda. He com pares the collembolans to the talitrid gammaridean amphipods on the basis of a restricted, albeit interesting, set of morphological similarities. Lawrence (2004: 621) claims that "... five years have passed [since his 1999 paper] without any evidence denouncing [bold face mine] the plausibility of the proposed change of class having been brought forward". Some comment is necessary. First, I hope that the use of the word denouncing was only a bit of friendly, editorial hyperbole. I took the original FORUM comments of Lawrence (1999) in the spirit I hope they were given, as observations relevant to a possible alternative hypothesis for the relationships of springtails. In that spirit, it should not be a matter of denouncing, but rather one of assessing which hypothesis ? hexapod, or crustacean, or some other affinities for the collembolans ? served to best organize the available information. As Lawrence nicely summarizes in his most recent paper on the subject, there are pros and cons, advantages and disadvantages, to taking up his hypothesis. Second, while it is true that no one else has explicitly taken up the issue of collembolan affinities, it is simply not true that we lack for any evidence on the subject. Lawrence hints at the potential importance of molecular sequence data for providing more insight into the problem, but he incorrectly implies that such investigations have yet to be made. The most effective way to evaluate the Lawrence hypothesis is to take a total evidence approach to the available data. In fact, the most recent paper in a series (Giribet et al., 2001; Wheeler et al., 2001; Wheeler et al., 2004) summarizes an astounding array of data relevant ? Koninklijke Brill NV, Leiden, 2005 Crustaceana 77 (10): 1263-1265 Also available online: www.brill.nl

We describe a new species of pygocephalomorph eumalacostracan from the Leitchfield Formation, Mississippian (Lower Carboniferous) of Kentucky, U.S.A. The fossils display a well-developed cephalothorax, pleon, and tail fan, and they show greatest affinity with other species within Tealliocarididae, especially to species of Pseudotealliocaris. The new species, Pseudotealliocaris holthuisi, is a second taxon of tealliocarid from the American Lower Carboniferous, the other being P. palinscari from the Mississippian of Pennsylvania. We compare the new species to other known species in the family and provide an overview of pygocephalomorph evolution.

The sub-title of this fascinating volume is “Ontogeny, Morphology, and Evolution.” In its comprehensive approach, it is an example of what can result if one is willing to look at situations differently, to break away from preconceptions, and to ask some new questions that begin with the phrase, “What if ... ?” In this case, what if we throw away the adultocentric view of ontogeny, i.e., directed at the adult organism, and look at ontogeny as embryocentric, a sort of on-going Markov process directed at the next stage and not at some final cause? As Minelli cautions us in the introductory chapter, the “existence of a feedback ... does not imply the existence of a programme.” There are many ways in which to look at nature, and there is value in the “multicentric view of development.”