FNZ 67 - Peloridiidae (Insecta: Hemiptera: Coleorrhyncha) - Introduction
Larivière, M-C; Burckhardt, D; Larochelle, A 2011. Peloridiidae (Insecta: Hemiptera: Coleorrhyncha). Fauna of New Zealand 67, 78 pages.
( ISSN 0111-5383 (print), ISSN 1179-7193 (online) ; no. 67. ISBN 978-0-478-34730-2 (print), ISBN 978-0-478-34731-9 (online) ). Published 14 Nov 2011
Peloridiidae or moss bugs are the sole extant members of the hemipteran suborder Coleorrhyncha. Seventeen (17) genera and 36 species are known from Chile, Argentina, New Zealand, New Caledonia, and eastern Australia including Tasmania and Lord Howe Island.
These ‘living fossils’, as they are often called, live in the wet moss of temperate and subantarctic rainforests. They display a disjunct circumantarctic distribution and are considered relics of a richer more widely distributed fauna thought to have its evolutionary roots in the Late Permian to the Late Cretaceous (approx. 250 to 65–80 ma).
Moss bugs have hardened forewings and do not possess hindwings, except for the South American Peloridium hammoniorum Breddin, 1897, in which some individuals’ hindwings are developed and functional. Consequently they are unable to fly, which makes them an ideal model group to test Gondwanan biogeographic hypotheses.
The New Zealand fauna (3 genera, 13 species) is endemic and accounts for 18% of world genera and 36% of world species. New Zealand has the most diversified fauna at the species level, followed by Australia, South America, and New Caledonia (see Table 1) although Australia has the greatest number of described genera.
The present work offers a concise faunal review of this ‘iconic’ Gondwanan group, reconciling results published by Burckhardt (2009: revision of world fauna) and by Burckhardt et al. (2011: revision of genus Xenophyes) with a study of specimens contained in New Zealand entomological collections and museums.
The goals of this faunal review are to provide an inventory of New Zealand taxa, a concise treatment of their taxonomy, identification keys to genera and species, and a summary of information available on species distribution and biology.
It is a further step in the authors’ goal of attaining an overall understanding of the Hemiptera fauna of New Zealand within a reasonable timeframe, and making comprehensive information available to a wide range of end-users.
In addition to paper-based publications by the authors further information on the fauna is available on The New Zealand Hemiptera Website (http://hemiptera. landcareresearch.co.nz/), including updated checklists, digital images, identification tools, and recent literature, and general information on Moss Bug Base (http://rameau.snv.jussieu.fr/cgi-bin/coleorrhyncha.pl/ ).
The first member of the Peloridiidae described from New Zealand was Xenophyes cascus Bergroth, 1924. Subsequently Drake & Salmon (1948, 1950), Woodward (1952, 1956, 1958), and Evans (1982) described additional species.
Woodward (1958) provided a key to the New Zealand taxa. Evans (1982) supplied a comprehensive review of the world fauna, including a discussion on distribution, generic relationships, and dispersal as well as an account of anatomy and morphology. This author firmly established the taxonomy of New Zealand genera (Oiophysa, Xenophyes, Xenophysella), which is in use to this day, and recognised 10 species for the fauna. Evans produced very useful habitus illustrations of the New Zealand taxa but he did not provide identification keys in his world review. Furthermore, his study was based on very limited material from New Zealand and, although it is still regarded as a ‘classic’ in the field of Peloridiidae taxonomy, it failed to capture the extent of morphological variability between and within populations.
The most comprehensive revision of the world fauna to date is that of Burckhardt (2009), who provided descriptions and keys to all taxa (adult and nymphal stages), a cladistic analysis, and biogeographical discussion. Burckhardt maintained the generic classification of previous authors, synonymised Oiophysa fuscata Drake & Salmon, 1950 with Oiophysa ablusa Drake & Salmon, 1950, as well as Xenophysella dugdalei Evans, 1982 and Xenophysella pegasusensis Evans, 1982 with Xenophysella stewartensis (Woodward, 1952); and he described two new species for New Zealand (Oiophysa paradoxa and Xenophysella greensladeae). Burckhardt, in Burckhardt et al. (2011), described four new species of Xenophyes. Consequently, three genera and 13 species are now recognised from New Zealand. Burckhardt’s revision included also a taxonomic treatment of the last instar of New Zealand species.
In the context of his world revision, Burckhardt (2009) included selected material from each region of the world. The New Zealand material comprised types, specimens from overseas museums, and specimens collected by him during two visits to the country (1992, 2000). Burckhardt’s study included only some of the specimens deposited in New Zealand entomological collections and museums.
The current concise faunal review is based on all available specimens (over 2,400) from these museums and collections. This study material provided a solid basis on which to test taxonomic concepts and other information published by Burckhardt (2009) and Burckhardt et al. (2011), and to apply results comprehensively at the regional level.
Higher classification and phylogeny
The phylogenetic position of Peloridiidae within the order Hemiptera has been contentious for a long time. In the past, moss bugs have been variously assigned to Heteroptera or Homoptera. Today, they are generally considered be the sole extant member of the hemipteran suborder Coleorrhyncha which is considered to be the sister group to the suborder Heteroptera.
The phylogenetic analysis of Burckhardt (2009), summarised in a simplified version of his cladogram (p. 12), was the first attempt to apply a strict cladistic methodology to the morphological analysis of relationships among world Peloridiidae. A similar basic branching pattern as that of Burckhardt (2009) — (New Zealand/New Caledonia (South America + Australia)) — was uncovered in a previous, more narrative phylogenetic analysis by Popov & Shcherbakov (1996). The two studies uncovered a cladogram topology mostly consistent with the diversification of moss bugs as a consequence of the break-up of Gondwana. Earlier, Evans (1982) discussed intergeneric relationships but did not provide characters supporting his ideas.
Important differences from previous studies were revealed in Burckhardt (2009), e.g., a different phylogenetic position of the genera Oiophysella (New Caledonia), Peloridium (South America), and Howeria (Lord Howe Island) relative to other world genera, and a different sister group relationship between Xenophysella and Oiophysella (Xenophyes + Oiophysa). Previous hypotheses included, for example, the placement of Xenophyes as ‘most ancestral taxon’ (Evans 1982) or as sister-taxon to Xenophysella, and Oiophysa as most closely related to Oiophysella (New Caledonia) (Popov & Shcherbakov 1996).
Readers are referred to Burckhardt (2009) for a more detailed discussion of Peloridiidae higher classification and phylogeny, and Popov & Shcherbakov (1991, 1996) for a world overview of fossil Coleorrhyncha and phylogenetic considerations based on the fossil record.
Burckhardt (2009) provided a discussion of the historical developments of biogeographical concepts and analyses together with his own general perspective on the biogeography of the peloridiid world fauna. He concluded that “no detailed biogeographical conclusions can be drawn at the moment as neither the cladogram is sufficiently resolved nor the distribution is known in enough detail.” A better-resolved phylogeny can be obtained through the discovery of new, phylogenetically informative morphological and/or molecular characters. Colleagues from Denmark and Germany are currently investigating molecular data. The lack of detailed distributional data, deplored by Burckhardt (2009), which is probably more important in the present context than insufficient resolution of the cladogram, is remedied by the present study. In New Zealand species distributions are now well documented, and as a consequence, it is possible to give a brief biogeographical account for the fauna. In the following discussion any indication of putative relationships among species follows the cladogram on page 12.
The overall distribution of New Zealand Peloridiidae is summarised in Table 2 and in Maps 4–6 (pp. 70–72). Species distributions are largely allopatric within genera. The genera Xenophyes and Oiophysa occur on the North and South Islands. Oiophysa is also represented by one species endemic to Stewart Island (O. paradoxa). The genus Xenophysella has a more restricted distribution in mid- and southwestern areas of the South Island; it also has one species (X. stewartensis) endemic to Stewart Island.
The majority of Peloridiidae (10 species or 77% of the fauna) occur on the South Island; 8 species (Oiophysa ablusa, O. distincta, Xenophyes adelphus, X. goniomus, X. kinlochensis, X. metoponcus, X. rhachilophus, Xenophysella greensladeae) are restricted to this island. No species is restricted to the North Island although Oiophysa cumberi and Xenophyes cascus are widely distributed and mostly occur there, with a few populations also present in northernmost areas of the South Island. Only the genus Xenophyes has so far been recorded from the far north of New Zealand. The apparent absence of Oiophysa from the Northland area north of the Auckland isthmus is intriguing. The distribution range of Oiophysa pendergrasti, apparently a close relative of O. cumberi, appears to follow the same general pattern but material to hand suggests O. pendergrasti is locally less abundant. Further field collecting is required to investigate the occurrence of O. pendergrasti on the Coromandel Peninsula, to the apparent exclusion of O. cumberi, and the apparent absence of the genus Oiophysa from the Northland region (northernmost North Island). Xenophyes cascus and X. rhachilophus are the most widely distributed and locally most abundant of all New Zealand species. Among species occurring on the two main islands of New Zealand, Oiophysa ablusa and Xenophyes metoponcus have the most restricted distributions, in the northwest corner of the South Island and its central West Coast respectively. The fauna of Stewart Island is known only from two species, Oiophysa paradoxa and Xenophysella stewartensis. Peloridiidae have never been recorded from New Zealand’s offshore islands, neither from the Three Kings Islands or Kermadec Islands in the North nor from the Chatham Islands or other Subantarctic islands (Antipodes Islands, Auckland Island, Bounty Islands, Campbell Island, The Snares).
Burckhardt (2009) and Burckhardt et al. (2011) identified species pairs (hypothesised sister-species) with allopatric or parapatric (in Xenophyes) distributions, that may have diversified as a result of vicariance: Xenophysella greensladeae – stewartensis (South Island – Stewart Island); Oiophysa ablusa – paradoxa (South Island – Stewart Island); Oiophysa cumberi – distincta (North Island and northern South Island – central to southwest South Island); Xenophyes cascus – rhachilophus (North Island and northwest to central South Island – central to southwest South Island); Xenophyes goniomus – kinlochensis (central northwest South Island – southwest South Island).
Biology and dispersal
Estévez & Remes Lenícov (1990) and Burckhardt (2009) showed that peloridiids have five morphologically distinct nymphal instars. Cassis & Gross (1995) noted that mating occurs in spring in Australia and overwintering is probably spent in the egg-stage. In New Zealand adults have been found from spring to autumn, mostly from December to March; tenerals, newly emerged adults, have generally been collected in late spring, summer, and autumn, mostly in January (North Island) or February (South Island); nymphs have been captured mostly from November to December (North Island) or from January to February (South Island). Surveys conducted during the New Zealand winter (mainly June to September) have yielded a few adults only; no tenerals or nymphs have been recovered in that season. This may be indicative of a life cycle with overwintering adults and/or eggs.
Although Peloridiidae are commonly found in association with wet moss and sometimes hepatics, the specificity of these relationships remains unclear. Hacker (1932) was the first to establish the link between peloridiids and mosses. However, in their study of Hackeriella veitchi in Australia, Helmsing & China (1937) were the first to establish that peloridiids actually feed on mosses. In New Zealand the only published moss-association record is that of Carter (1950), who reported adults and nymphs of Xenophyes sp. to be found on Psilopilum crispulum. More than one peloridiid species can commonly be found together in the same locality and even microhabitat (see Appendix D, p. 40). Known associations between world peloridiids and mosses or hepatics are summarised in Table 3 (see also Burckhardt 2010).
Analysis of label data from specimens in New Zealand collections and personal field experience (D. Burckhardt and M.-C. Larivière, pers. observations) suggest that apart from requiring a year-round humid environment Peloridiidae are relatively eurytopic in terms of their macrohabitat requirements. This means that, in general, as long as there is rain- or mistforest it does not matter whether southern beech (Nothofagus) or other tree species are present or absent. It also seems that peloridiids are more often found on wet (almost saturated) moss and hepatics growing in association with trees, e.g., on or close to trees, surface roots, fallen dead branches and trunks, than on similar vegetation growing under favourably wet conditions elsewhere, e.g., open moss carpets. This reiterates and expands observations made by Carter (1950). Figures 129–144 provide examples of New Zealand peloridiid habitats.
All New Zealand species lack hindwings. They probably spend most of their life in the wet moss on which they feed, probably moving very little, and consequently having low dispersal ability. It is presumed that if environmental conditions become drier Peloridiidae move deeper into the moss layers in search of humidity, and remain there until it is again suitably wet nearer to the surface.
As is the case with their biology, little is known about the ethology of moss bugs. Peloridiidae, like other plant-sap sucking Hemiptera, possess endosymbiotic microorganisms located in special mycetomes (Müller 1951; Pendergrast 1962; Schlee 1969). Vibrational signaling and jumping, two features also known in other Hemiptera, have been observed by Hoch et al. (2006; Hackeriella veitchi, Australia) and Burrows et al. (2007) respectively.
MORPHOLOGY AND TERMINOLOGY
The main diagnostic features of adult Peloridiidae are detailed on page 19.
The reader may acquire the elementary knowledge of adult peloridiid morphology necessary to identify New Zealand taxa by reference to Figures 1–6, the glossary provided in Appendix A (p. 35), and other accounts of peloridiid morphology discussed by Burckhardt (2009), whose morphological terminology is generally adopted here. The term genitalia rather than terminalia (Burckhardt et al. 2011), is used to refer to the modified genital segments of the abdomen and associated structures involved in copulation, fertilisation, and oviposition.