Order BLATTODEA Brunner von Wattenwyl, 1882 (incl. Isoptera)

Blattodea

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Order BLATTODEA Brunner von Wattenwyl, 1882 (incl. Isoptera)

Cockroaches

Compiler and date details

January 2012 - ABRS following advice from D.C.F. Rentz

30 June 1997 - A.M.E. Roach & D.C.F. Rentz, CSIRO Entomology, Canberra, Australian Capital Territory, Australia

Introduction

Cockroaches are orthopteroids that are considered to be most closely related to termites and mantids. They are well known in the fossil record and seem to have been especially abundant in the late Palaeozoic, some 300 million years ago. The order is of moderate size with approximately 4000 species in 460 genera worldwide. It is expected that the size of the Blattodea will increase dramatically in numbers of species because some of the diverse families, such as the Blattellidae, are, as yet, very poorly studied. Five hundred and thirty-three species are now recognised from Australia and in excess of 90% of these are considered endemic.

Some of the world's smallest and largest cockroaches are found in Australia. Adults of Nocticola Bolívar can measure as little as 3 mm long while those of Macropanesthia rhinoceros Saussure are up to 80 mm in length and rank among the heaviest of insects, sometimes weighing 33 grams. Cockroach taxonomy can be a rewarding pursuit in Australia because many groups have been little studied.

CLASSIFICATION
When this checklist was first compiled in the Zoological Catalogue of Australia (Roach & Rentz 1998), the higher classification was considered to be unstable. At least three 'modern' classifications were in use. Princis (1960) used classical morphological characters such as wing venation and folding, patterns of the spines on the legs and the shape of the male subgenital plate. He integrated this into Handlirsch's (1926–1930) system and recognised four suborders, 28 families and 21 subfamilies. McKittrick (1964) used ovipositional behaviour of the female combined with the structure of the male and female genitalia and associated musculature and morphology of the proventriculus to arrive at a classification that included only two superfamilies and five families with 20 subfamilies. The subfamily Tryonicinae of the Blattidae, known from Australia and New Caledonia, was added later. McKittrick's (1964) classification is strongly supported by studies such as that of Roth (1970). Grandcolas (1993) and Roth (1988) made important changes relevant to McKittrick's classification (1964). The classification used in Rentz (1998), and originally published as Roach & Rentz (1988), followed the classification set out in The Insects of Australia by Mackerras (1970) and subsequently Roth (1991a). A revised classification is now available (Beccaloni & Eggleton 2011) and is followed here.

It seems to us that anyone attempting to construct a catalogue of cockroaches faces more problems than might be expected. If true, what might be the reasons?

Possibly usage may be the first. Some cockroach names appear extensively in the literature, especially the species implicated in economic or medical problems. The extensive use of a relatively small number of species, sometimes of uncertain taxonomy, in physiological, morphological and embryological studies, provides an overload of information about the insect, but not about its taxonomy or synonymies. However, the bulk of cockroach species are mentioned once when they are described and then rarely afterwards. Many of these early descriptions are inadequate with poor or no illustrations, making the species difficult to identify, and providing no life history information.

The second problem stems from the difficulty of identifying species, genera and higher taxa due to their often conservative external features. The problems of the use of the names is the responsibility of the 'experts', the taxonomists who have named them. Quite often blattoid studies have appeared as 'appendices' in treatments of the orthopteroid insects of particular geographic areas. Many of the authors of such works have been specialists on one or more orthopteroid groups but not Blattodea. Because of the nature of their studies, they felt compelled to provide names for the supposed new species included in their lists. As a result, generic placements were often incorrect and species were often described more than once. Even experienced workers find great difficulties in constructing a key to the families and subfamilies based on external characters alone and convergence and parallel evolution can easily go unnoticed. Many species, therefore, have been assigned to incorrect higher taxa or even the wrong family. Cockroach higher classification is unstable, although some headway has been made in recent years by the use of internal characters such as the proventriculus, the genitalia of both sexes and the ovipositional behaviour of the female. The greatest problem is at the species level as far as nomenclature is concerned. Most cockroaches have highly complex, but species-specific, concealed genitalia. Until about 30 years ago, genitalia were generally not examined. Recent assessment of genitalia has shown many generic placements to be incorrect. The result has been a nightmare for the cataloguer, the taxonomist and the researcher. This catalogue will help to rectify past errors and provide entry to the complex cockroach literature.

Rentz & Cameron (1983) presented a catalogue of Australian cockroaches, including adventives, described to that date. Roth (1991a) summarised the taxonomic information on the Australian species but since then he and others have added many references to the literature.

BIOLOGY

Cockroach biology was reviewed by Chopard (1938) and Cornwell (1968) and since then many additional studies have been made such as those by Guthrie and Tindal (1968) and Schal et al. (1984). Further references can be found in Roth (1991a). Princis (1963–1971) catalogued the biological and taxonomic literature.

The Australian fauna consists of many interesting biological components. It must be realised that the vast majority of cockroaches have not yet been studied biologically or ecologically. The few that have reveal an array of biological strategies, many of which are unique. The often abundant wood-eating panesthiine cockroaches are probably very important in the breakdown of logs in the wet forests; these cockroaches seem to have some communal organization since they are commonly found in groups. Geoscapheiines are endemic to Australia and have a burrowing habit and life-cycle spanning several years; they can be exceedingly abundant in certain areas and since their food consists of fallen leaves, they must be important in the recycling process. The continent also harbours a fauna of diurnal cockroaches most of which are strikingly colourful. Several seem to be part of Muellerian mimicry complexes. Many polyzosteriine cockroaches are diurnal. These are unusually large and often colourful and can be found moving on the ground or perched high in the bushes in the full sunlight. Blattellids of the genera Ellipsidon and Balta are some of the most colourful of Australian cockroaches and can be found on flowers or basking in the sun on leaves during the day. Many of these cockroaches seem to mimic lycid beetles and have white antennal tips, an alluding effect that 'shortens' the antennae. Caves on both sides of the continent contain unrelated cockroaches which exhibit all of the characters commonly associated with cave dwellers, such as absence of colour, elongate body shape and legs, lack of eyes and reduced or absent wings and tegmina.

Cockroaches produce groups of eggs enclosed together in single capsules, called oöthecae, in all but a few species. Panesthiinae give birth to live young. The blaberid Perisphaerus, represented in the Australian fauna by an undescribed species and, therefore, not appearing in this work, may protect its young after live birth if it is like its relatives. According to Roth (1981), the nymphs cling to the undersurface of the mother for at least two instars. During this time they are blind and have specialised non-chewing mouthparts that fit into special orifices between the mother's coxae which may dispense food. But this species, like so many others in the Australian fauna has not been studied.

Those species that have been studied fall into two groups: oviparous species and ovoviviparous

Oviparous species (those that reproduce by eggs laid outside the body in an oötheca) produce a pale, soft oötheca that hardens when exposed to air. This includes all Australian species other than Blaberidae. The ovipositor valves serve as a mould that forms the oötheca. The colour, size, ornamentation, serrations of the oötheca and the number of eggs can be diagnostic. Each egg is in a shell surrounded by an air space with an air duct in the keel. The egg case is carried for various lengths of time before it is deposited. Species of the introduced genus Blattella carry the oötheca for the entire embryonic period.

Oviparous cockroaches vary in the way the oötheca is deposited. This can be of crucial importance in assessing the relationships of the species. Some simply drop the egg case; others glue it to the substratum and cover it with bits of bark; others dig a small hole and place the oötheca quite deep in the ground. The manner of placement of the oötheca is also very characteristic. In some species, the keel when formed, faces vertically relative to the mother carrying it. These oöthecae are deposited with the keel facing upwards. Other species rotate the oötheca by 90º when it is formed, and deposit it in that way. In all of these species, hatching seems to be a 'group activity'. The embryos swallow air, become inflated and force separation of the halves of the keel and emerge simultaneously.

Ovoviviparous species occur in the Blaberidae; the introduced Blattella species are ovoviviparous. The mode of reproduction in these taxa represents a specialisation: the oötheca is completely extruded and then retracted into the uterus or brood sac where eggs develop. Other ovoviviparous species in the geoscapheine genera Macropanesthia, Geoscapheus, Neogeoscapheus and Parapanesthia do not form an oötheca. The eggs of Macropanesthia species pass directly from the oviduct into the uterus where they develop in a mass. However, the eggs of a number of other geoscapheines are glued together in a regular raft, as they would be if enclosed in an oötheca. Generally, species in both ovoviviparous categories tend to have a larger number of eggs but produce fewer egg batches than the viviparous species.

Obligatory parthenogenesis is known for only one cockroach species, Pycnoscelus surinamensis (Linnaeus), a species introduced into Australia. Facultative parthenogenesis has been reported for most pest species. However, the biological peculiarities of the great majority of Australian species have yet to be studied.

ECONOMIC IMPORTANCE

Fewer than a dozen species have given the cockroaches a bad name among the general public, but those species are capable of transmitting some of the world's most important diseases. These species should be of great concern when they occur in hospitals and restaurants where they can contaminate food. Pope (1953), gave detailed experimental observations on life histories of all domestic species then known in Australia. Roth & Willis (1957, 1960) reviewed cockroach ecology and medical and veterinary importance. The introduced cockroaches of the family Blattidae, subfamily Blattinae, that cause economic problems can be identified with the key provided by Mackerras (1968); Periplaneta fulginosa, a recent introduction, is not included in this key. Park (1990) provided an overview of domestic cockroaches in Australia. With but one or two exceptions, the native Australian species do not and cannot cohabit with humans. They are closely tied to particular kinds of habitats and cannot survive if they are removed.

Acknowledgements

The preparation of this section of the Zoological Catalogue of Australia database formed part of the research undertaken by the CSIRO Division of Entomology, Canberra. We were greatly aided by a grant from the Australian Biological Resources Study which allowed Ms Roach to devote full time to this task for a year. Divisional resources were made available to us.

The illustrations used in the family introductions of the published Catalogue are from Roth (1991a), with the exception of the Nocticolidae which was prepared for ABRS by Mr Frank Knight.

The authors wish to thank the following people for assistance, information and help: CSIRO Black Mountain Library, Canberra, ACT; Dr L.M. Roth, Harvard University, Cambridge; Dr H. Rose and Mr J. Walker, Sydney University; Dr G.B. Monteith, Queensland Museum; Dr E. Matthews, South Australian Museum; Mr E.D. Edwards, Ms Judith Newland, and a number of other staff members of the CSIRO Division of Entomology. Dr P. Grandcolas and Dr G.B. Monteith are thanked for reviewing the manuscript. The staff of the Australian Biological Resources Study, especially Drs W.W.K. Houston and A. Wells, have been helpful and provided encouragement during the preparation of this manuscript.

Database Notes

The information on the Australian Faunal Directory site for the Blattodea is derived from the Zoological Catalogue of Australia database compiled on the Platypus software program. It incorporates changes made to the work published on 2 September 1998 as (Roach, A.M.E. & Rentz, D.C.F., 1998)

Families are listed in the taxonomic order given in Roth (1991a).

Generic synonymies for introduced species are for Australian taxa only.

Type information is given almost exclusively for primary types; details for the paratypes can be found by consulting the references. Syntype status is assumed if the original description does not indicate clearly whether a holotype was designated.

There is confusion regarding many of Tepper's 'types' because he did not designate his type specimens at the time he described his species. The labels were added later, many on specimens not even mentioned with the descriptions. Such type associations are not valid. Dahms (1972) discussed the problem of Tepper's cockroach types, and Mackerras solved most of the Blattidae problems in her revisions.

Scalida Hebard, listed in Rentz & Cameron (1983) is no longer considered to occur in Australia. The only species recorded from Australia, S. debilis (Hanitsch), was transferred to Parasigmoidella by Roth (1991b).

Zoogeographic designation for extralimital distributions follows Cranston & Naumann (1991). New Guinea is used in the zoogeographical sense, Irian Jaya and Papua New Guinea are not used. Non-Australian localities are quoted in their modern names but it was not possible to check all cases.

Only original name forms have been used for species; endings have not been corrected for gender of genus name as per proposals in the new draft ICZN Code, 1995.

Relatively little is known of the biology of some groups of Australian cockroaches but considerable information is available for others. All of the relevant literature references are provided, although it must be noted that a considerable amount of literature exists on the biology, ecology and control of certain pest species. This is not dealt with here.

Common names are taken from Naumann (1993).

Limital Area

Distribution data in the Directory is by political and geographic region descriptors and serves as a guide to the distribution of a taxon. For details of a taxon's distribution, the reader should consult the cited references (if any) at genus and species levels.

Australia is defined as including Lord Howe Is., Norfolk Is., Cocos (Keeling) Ils, Christmas Is., Ashmore and Cartier Ils, Macquarie Is., Australian Antarctic Territory, Heard and McDonald Ils, and the waters associated with these land areas of Australian political responsibility. Political areas include the adjacent waters.

Terrestrial geographical terms are based on the drainage systems of continental Australia, while marine terms are self explanatory except as follows: the boundary between the coastal and oceanic zones is the 200 m contour; the Arafura Sea extends from Cape York to 124 DEG E; and the boundary between the Tasman and Coral Seas is considered to be the latitude of Fraser Island, also regarded as the southern terminus of the Great Barrier Reef.

Distribution records, if any, outside of these areas are listed as extralimital. The distribution descriptors for each species are collated to genus level. Users are advised that extralimital distribution for some taxa may not be complete.

Zoogeographic designation for extralimital distributions follows Cranston & Naumann (1991). New Guinea is used in the zoogeographical sense, Irian Jaya and Papua New Guinea are not used. Non-Australian localities are quoted in their modern names but it was not possible to check all cases.