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Geological Society, London, Special Publications doi: 10.1144/GSL.SP.2004.228.01.19 p419-453. 2004, v.228; Geological Society, London, Special Publications   Jorge F. Genise   ants and termites trace fossils in palaeosols attributed to coleopterans, Ichnotaxonomy and ichnostratigraphy of chambered service Email alerting new articles cite this article to receive free e-mail alerts when here click request Permission part of this article to seek permission to re-use all or here click Subsc
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  Geological Society, London, Special Publicationsdoi: 10.1144/GSL.SP.2004.228.01.19p419-453. 2004, v.228; Geological Society, London, Special Publications    Jorge F. Genise   ants and termitestrace fossils in palaeosols attributed to coleopterans, Ichnotaxonomy and ichnostratigraphy of chambered serviceEmail alerting new articles cite this article to receive free e-mail alerts whenhereclick requestPermission part of this article to seek permission to re-use all orhereclick Subscribe Collection London, Special Publications or the Lyell to subscribe to Geological Society,hereclick Notes © The Geological Society of London 2013  at CAPES on April 8, 2013http://sp.lyellcollection.org/ Downloaded from   Ichnotaxonomy and ichnostratigraphy of chambered trace fossils in palaeosols attributed to coleopterans ants and termites JORGE F. GENISE CONICET, Museo Paleontolrgico Egidio Feruglio, Av. Fontana 140, 9100 (Trelew), Chubut, Argentina (e-mail: jgenise@mef org.ar) Abstract Most recorded trace fossils in palaeosols are burrows and chambers attributed to bees, ants, termites and coleopterans. Ichnogenera attributed to bees are grouped in the ichno- family Celliformidae, whereas those attributed to ants, termites and coleopterans are included herein in the new ichnofamilies Pallichnidae, Krausichnidae and Coprinisphaeridae respec- tively. Shape, type of wall, fillings and associated burrows of chambers are the main morpho- logical ichnotaxobases used for this classification; they are weighed with regard to the behaviour and architecture of the supposed trace-makers. Coprinisphaeridae are spherical, pear-shaped or ovoid structures, having active or passive fillings and constructed walls. The ichnogenera included are: Fontanai, Coprinisphaera, Eatonichnus, Monesichnus, Teisseirei and Rebuffoichnus, attributed to coleopterans. The similar Pallichnidae show lined or structureless walls, and include Pallichnus, Fictovichnus and Scaphichnium, also attributed to coleopterans. The Krausichnidae constitutes trace fossils composed of chambers of different shapes inter- connected by burrow systems of inconsistent diameter or isolated chambers associated with burrow systems of different diameters. The Krausichnidae include Attaichnus, Parowanichnus, Krausichnus, Archeoentomichnus, Tacuruichnus, Vondrichnus, Fleaglellius, Termitichnus and Syntermesichnus, attributed to ants and termites. The stratigraphic ranges of insect ichnotaxa in palaeosols are reviewed and compared with the body fossil record of potential trace- makers, revealing that in most cases insect trace and body fossils show similar ranges. As stated by earlier authors, the Cretaceous was a critical period during which the oldest body fossils of dung-beetles, bees, termites and ants are recorded, whereas the trace fossils of these groups are recorded from this period or shortly after, during Cenozoic times. The grouping ofichnogenera in ichnofamilies is an uncommon but commendable trend in some branches of ichnology, where highly significant ichnotaxobases can be used to make coherent groupings of ichnotaxa (e.g. Genise 2000; Bertling et al. 2003; Rindsberg & Martin 2003). Roselli (1939), a pioneer in insect palaeoichnology, first suggested a higher taxonomy for the hymenopteran and coleopteran trace fossils that he described. In his contribution he grouped the supposed hymenopteran nests in the family Nidus Himenopterogenosidae and those of coleopterans in Nidus coleopterogenosidae (Roselli 1939). Recently, Genise (2000) created the first ichnofamily for insect trace fossils in palaeosols, Celliformidae, to include Celliforma and allied ichnogenera. This contribution repre- sents an attempt to classify many of the remaining chambered trace fossils in palaeosols, attributed to Coleoptera, Hymenoptera and Isoptera (Genise 1999), and to provide a general picture of the stratigraphic ranges of insect ichnotaxa in palaeo- sols. It also represents an attempt to identify the major behavioural features of these groups as reflected in the morphology of their trace fossils. Few trace fossils constructed by organisms other than insects can be compared morphologi- cally with insect traces. The more complex the architecture, the more difficult it is to find analogous structures outside the insect realm. Probably the most similar trace fossils are those produced by another group of arthropods: crustaceans. Tunnels associated with chambers are known from crayfishes, whose trace fossils are included in the ichnogenus Camborygma Hasiotis & Mitchell 1993. However, Cambor- ygma shows a distinctive bioglyph composed of scrape and scratch marks, knobby and hum- mocky surfaces, pleopod and body impressions, all of which distinguish it from similar ichno- genera attributed to social insect nests. In addition, interconnected tunnels of very different diameters are absent, as in other known modern crustacean constructions (Bromley 1990). The ichnogenera Ophiomorpha and Thalassinoides, also attributed to crustaceans, commonly show burrow systems devoid of chambers (Bromley 1990), but Verde & Martinez (2004) described chambers having tiny tunnels radiating vertically from the upper part of the chambers, in connec- tion with both ichnogenera. Spongeliomorpha shows burrow systems in association with cham- bers in one ichnospecies: S. sicula D'Alessandro & Bromley 1995. The presence of large vertical shafts, small chambers below the maze of tunnels and the typical criss-cross pattern of grooves in From: MCILROY, D. (ed.) 2004. The Application of lchnology to Palaeoenvironmental and Stratigraphic Analysis. Geological Society, London, Special Publications, 228, 419-453.0305-8719/04/$15.00 9 The Geological Society of London. at CAPES on April 8, 2013http://sp.lyellcollection.org/ Downloaded from   420 J.F. GENISE Spongeliomorpha (D'Alessandro Bromley 1995) and the upper radiating tunnels in the chambers associated with Ophiomorpha and Tha- lassinoides separate these trace fossils from those of social insects. The morphology of insect ichnogenera devoid of tunnel systems has few similarities with other known ichnological structures. The specimen illustrated by H/intzschel (1975) of Amphorichnus papillatus Myannil 1966 superficially resembles Fictovichnus (Johnston et al. 1996); however, the former is a filling of an amphora-like hollow ending in a distinct apical protuberance (Pemberton et al. 1988; Edwards et al. 1998). Another case is that of the cocoons of earth- worms and leeches described by Manum et al. (1991) attributed to the genera Burejospermum Dictyothylakos and Pilothylakos. The former two were previously considered as a seed and a palynomorph respectively. These cocoons are more likely secretions of organisms (Manum et al. 1991) than structures resulting from their activity, and as such they are ruled out as trace fossils (Bertling et al. 2003). Also, the structure of these cocoons differs from that of insects (Manum et al. 1991), whose cocoons are true trace fossils. The ichnofossil Lithoplaision ocalae Diblin et al. 1991 may superficially resem- ble an insect chamber, but its conical shape and marine invertebrate remains in the wall are important differences from insect chambers. Continental ichnology, and particularly insect palaeoichnology, is an exciting topic that is developing quickly in a changing scene, in which new discoveries occur daily. Thus this con- tribution is written with the conviction that the classification and stratigraphy of trace fossils proposed herein will probably need to be updated in the near future. However, a first impression is presented herein, with the under- standing that it will help to order the somewhat chaotic ichnotaxonomy of insect trace fossils, providing a new standpoint from which to observe and analyse insect behaviour as reflected by trace fossils. heoretical background Even the most complex insect trace f6ssils in palaeosols can be morphologically divided into two components: burrows (tunnels, shafts and galleries) and chambers. The latter term has no specific definition in the ichnological literature and glossaries (e.g. Ekdale et al. 1984; Bromley 1990). However, it is commonly used to name distinct enlargements of burrows in the entomological literature (e.g. Stephen et al. 1969; Halffter Edmonds 1982; Grass6 1984; H611dobler Wilson 1990). These excavated chambers are used without further modifications for nesting or pupation, and in other cases they are used to house more complex constructions for nesting or pupation. The knowledge of insect nest architecture was developed mostly through entomological studies, with each group of insects having its own nomenclature for exca- vated chambers and constructed structures of different functions. Some terms used in the ento- mological literature are pupation cell (e.g. Scholtz 1988; Skelley 1991), brood cell (Stephen et al. 1969; Batra 1984), brood ball chamber (Halffter Matthews 1966; Halffter Edmonds 1982), fungus garden chamber (H611dobler Wilson 1990) and royal cell (Grass+ 1984), among others. The functions of these chambers are diverse, but usually they are related to nesting activities or pupation - in sum, to the successful development of larvae. Fossil nests and pupation cells of Coleoptera, Hymenoptera and Isoptera respectively are the most common insect trace fossils in palaeosols (Genise et al. 2000), a fact that was related to the high potential of preserva- tion of these constructed or lined structures (Genise Bown 1994a). Females of most solitary bees and wasps nest- ing in soils, as well as dung-beetles, prepare chambers or structures constructed inside them, in which they provision food (pollen, nectar, prey, carrion or vertebrate excrement), lay an egg, and close the entrance immediately after. A single larva feeds on these provisions and com- pletes its development without the assistance of adults in most cases (Evans 1963; Halffter Matthews 1966; Batra 1984). In other groups of solitary insects having recorded trace fossils in palaeosols, such as weevils (e.g. Lea 1925; John- ston et al. 1996; Genise et al. 2002b), the larvae are not restricted to chambers prepared by adults. Their development takes place in the soil, in which they move freely, feeding on vege- table matter until their pupation, whereupon they prepare a cell that protects them during this critical period before emergence as adults (e.g. Loi~icono Marvaldi 1994). In turn, social insects such as ants, termites and some bees provision and inhabit the underground nests in which they lay eggs, and rear larvae that are confined to the interior of chambers (Michener 1974; Grass6 1984; H611dobler Wilson 1990). These main behavioural differences, and a large number of more specific ones, gave rise to the great morphological diversity of insect nest- ing and pupation structures in soils and palaeo- sols. Thus the available ichnotaxobases by at CAPES on April 8, 2013http://sp.lyellcollection.org/ Downloaded from   ICHNOSTRATIGRAPHY OF TRACE FOSSILS IN SOILS 421 which to classify ichnogenera in ichnofamilies depend on the features of chambers and asso- ciated structures, especially shape, wall, fillings and burrows. Accordingly, the former ichnofam- ily proposed earlier for insect trace fossils in palaeosols, Celliformidae Genise 2000, was based on various characters of cells, the usual name that hymenopterists give to the brood chambers made by wasps and bees (Evans 1963; Stephen et al. 1969; Michener 1974). lchnot xob ses Four ichnotaxobases, the most common charac- ters used as the basis of ichnotaxa, were listed and analysed by Bromley (1990): general form, type of wall structure, type of branching, and nature of the fill. Of these ichnotaxobases, branching is a less important character for classi- fying insect fossil nests, than the cross morphol- ogy of the entire burrow system is considered herein as an effective ichnotaxobase for insect traces. Shape Excavated and constructed chambers show a morphological continuum that ranges from flat and tabular shapes to spherical ones. Fortu- nately, discontinuities exist within this spectrum and also some complementary characters that favour the separation of the range as a whole into discrete units such as ichnogenera. The shape of the chambers is an important character for termite and ant nests, but it is even more cri- tical for separating trace fossils attributed to bees and beetles, because in the latter cases the asso- ciated burrows are rare. Celliformidae (attribu- ted to bees) can be recognized by the presence of cells having rounded backs and flat or conical tops showing a spiral design that was constructed from the outside by the adult bee (Fig. 1). In con- trast, closed pupation cells attributed to beetles have both extremes rounded and smoothed because the larvae themselves construct them from the inside. Among trace fossils attributed to beetles, there is a clear morphological discon- tinuity between spherical or pear-shaped traces, namely Coprinisphaera Sauer 1955, Fontanai Roselli 1939 and Pallichnus Retallack 1984, and ovoid ones: Monesichnus Roselli 1987, Fictovich- nus Johnston et al. 1996, Teisseirei Roselli 1939, Rebuffoichnus Roselli 1987 and Eatonichnus Bown et al. 1997. Among the ovoid forms, it is impossible to distinguish different shapes, with the single exception of Teisseirei, which shows a depressed outline in cross-section (Fig. 3c). Sca- phichnium Bown Kraus 1983 is unique because it has a peculiar hamate or lunate shape. Fossil termite and ant nests show a more or less continuous spectrum, from flat chambers in Krausichnus Genise Bown 1994b, Fleagletlius Genise Bown 1994b and Archeoentomichnus Hasiotis Dubiel 1995a, to spherical chambers in Attctichnus Laza 1982, Termitichnus Bown 1982 and Vondriehnus Genise Bown 1994b. In most cases, other complementary characters are needed to separate these ichnotaxa. However, some morphological discontinuities can be recognized in the spectrum of shapes. Krausich- nus and the unnamed termite nests from the Plio- cene and Pleistocene of Africa (Coaton 1981; Schuster et al. 2000) display low, flat, tabular chambers, whose floor and roof are parallel. Vertical pillars commonly accompany these chambers, probably to reinforce the whole struc- ture (Fig. 5b). These tabular chambers are clearly distinguishable from other flattened, but more oval, high chambers (e.g. Fleaglellius in which the roof is more arched with respect to the floor (Fig. 6b). Tabular chambers are apparently also present in Archeoentomichnus (Hasiotis Dubiel 1995a) and in Termitichnus namibiensis Miller Mason 2000. However, in the latter the tabular chambers seem to be more likely the result of a tiered arrangement of meniscate burrows, probably made by another organism. The complex architecture of social insects may result in secondary chamber systems within a primary chamber system. This is true, for instance, in Krausichnus trompitus, where the tab- ular chambers are grouped in spindle-shaped structures that are, in turn, connected with other spindles (Genise Bown 1994b). Similarly, in Tacuruichnus, a single chambered trace fossil supports a boxwork with chambers in the thick peripheral wall (Genise 1997) (Fig. 5c). Types of wall This ichnotaxobase is the most difficult to ana- lyse because of the different common usages of the term 'wall' (e.g. Retallack 2001b) and the complexity that walls can reach in insect traces. Commonly speaking, the term 'wall' is applied indistinctly to two different structures: two- dimensional surfaces (e.g. 'burrow boundary' of Bromley 1990, 1996) and discrete three-dimen- sional constructions. This fact introduces some confusion, and is discussed below. In an excavated chamber the wall is the boundary between the cavity and the soil - for instance the brood ball chamber wall in dung-beetle at CAPES on April 8, 2013http://sp.lyellcollection.org/ Downloaded from 
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