Family LYGAEIDAE

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Family LYGAEIDAE

Compiler and date details

15 February 2002

Introduction

The Lygaeidae are a cosmopolitan family comprising three subfamilies (Ischnorhynchinae, Lygaeinae and Orsillinae) (Henry 1997), 102 genera and 968 species (Slater & O'Donnell 1995; Henry 2009). The family is represented in the Australian fauna by all three subfamilies, 22 genera and 80 species.

Schilling (1829) provided the first formal recognition of the Lygaeidae as a family, although previous workers, including Duméril (1806) and Fallén (1807, 1829), had recognised the authenticity of a lygaeid group. Like much of the higher classification of the Heteroptera, the intrafamilial classification of the Lygaeidae was based on that of Stål (mostly 1874).

The history of the classification of the Lygaeidae prior to Henry (1997) is adequately summarised by Slater (1964a), Slater & O'Donnell (1995), Schuh & Slater (1995) and Péricart (1998). Modern works that have had a significant impact on lygaeid classification include Ashlock (1957), Slater & Hurlbutt (1957), Southwood & Leston (1959), Scudder (1959), Slater & Sweet (1961), Sweet (1967, 1981), Štys (1967) and Hamid (1975).

Until recently, the Lygaeidae sensu lato were composed of the Ischnorhynchinae, Lygaeinae and Orsillinae, as well as the Artheneidae, Blissidae, Cryptorhamphidae, Cymidae, Geocoridae (including Bledionotinae, Henestarinae and Pamphantinae), Henicocoridae, Heterogastridae, Ninidae, Oxycarenidae, Pachygronthidae, Psamminae and Rhyparochromidae (including the Plinthisinae).

Henry (1997) in his seminal work on the Lygaeoidea, established the paraphyly of the Lygaeidae sensu lato. In his classification, several lygaeid subfamilies are given family rank (Artheneidae, Cryptorhamphidae, Ninidae, Oxycarenidae and Pachygronthidae); the family status of the Blissidae, Cymidae, Geocoridae, Heterogastridae and Rhyparochromidae is restored; and the monotypic Henicocoridae are transferred from the Lygaeidae to the Idiostoloidea. Henry (1997) also proposed a sister-group relationship between the Lygaeidae and the Piesmatidae plus Štys' (1967) 'malcid-line' of taxa.

Henry (1997) established the Lygaeidae sensu stricto (Ischnorhynchinae + Lygaeinae + Orsillinae) on the basis of the following character states: transverse impression across the calli, raised pattern on the scutellum and dorsal position of abdominal spiracles II–VII. Scudder (1962) and Slater (1964b) had alluded previously to the relationship of the above subfamilies. There is no tribal classification for the Ischnorhynchinae and Lygaeinae. Ashlock (1967) proposed a tribal classification for the Orsillinae (Lepionysiini, Orsillini, Metrargini and Nysiini) which was followed by Cassis & Gross (2002).

The Ischnorhynchinae are a small cosmopolitan family comprising 15 genera and 77 species (Slater 1964a, Slater & O'Donnell 1995). Scudder (1962) revised the world fauna. Regional works of significance include Barber (1953; Nearctic Region), Scudder (1958; Australia), Scudder (1964; South Africa), Ashlock & Scudder (1966; Neocrompus China, Melanesia and Polynesia), Zheng et al. (1979; China), Slater & Brailovsky (1989; Neotropical Region) and Péricart (1998; western Palaearctic Region). Ischnorhynchines are most diverse in the Afrotropical, Palaearctic and Oriental Regions. Pylorgus Stål is the only broadly distributed genus, and is found throughout the Eastern Hemisphere. The Australian fauna includes five genera (Acanthocrompus Scudder, Cerocrompus Scudder, Crompus Stål, Koscocrompus Scudder and Pylorgus) and six species. Among these, two genera, Cerocrompus and Koscocrompus, and all species are endemic. The subfamily is represented in all States and territories of Australia and most species are broadly distributed.

The Lygaeinae are the most diverse lygaeid subfamily and comprise 57 genera and 640 species (Slater & O'Donnell 1995). Lygaeines are found in all major zoogeographic regions and are most diverse in the tropics. Slater (1964b), Slater & Sperry (1973) and Linnavuori (1978) described much of the Afrotropical fauna. Most Afrotropical genera are also found in either the Palaearctic and/or Oriental Regions, with a number of genera also occurring in the Australian Region (Arocatus Spinola, Aspilocoryphus Stål, Graptostethus Stål, Melanotelus Reuter and Spilostethus Stål). Péricart (1998) described the western Palaearctic fauna, recognising 17 genera, seven of which are restricted to the Region, and only the nominotypical genus, Lygaeus Fabricius, has an Holarctic distribution. The Oriental fauna is the least well known and currently contains 20 genera (Slater & O'Donnell 1995). Hamid & Meher (1976) revised the Pakistani fauna and Scudder (1963) described species in the Astacops complex of genera. Most of the Oriental genera are shared with the Afrotropical and/or Australian Regions. The Neotropical Lygaeinae fauna is diverse and insular, with 14 of the 20 described genera restricted to the Region. Most of the other genera are shared with the Nearctic Region. Brailovsky & Barrera (1985) and A. Slater (1992) described much of the fauna of this Region, which is relatively depauperate with only eight described genera (A. Slater 1992).

A. Slater (1978, 1985) revised Australian lygaeines. The Australian Lygaeinae fauna comprises 13 genera and 62 species. Most genera are also found extralimitally, often having Indo-Pacific distributions (sensu Schuh & Stonedahl 1986), or occurring in common with Melanesia and/or the Oriental Region. Woodwardiastes A. Slater is the only endemic genus. The lygaeine species are mostly endemic and only nine species also occur outside Australia. The most speciose genera in Australia are Arocatus (6 species), Oncopeltus Stål (6), Scopiastella Slater (9) and Scopiastes Stål (17). Many Australian species of Lygaeinae are widespread and the following general distribution patterns are recognised: broad distribution across tropical Northern Australia; ubiquitous along the eastern seaboard; broad distribution across temperate Australia; and, widespread throughout the arid and semi-arid areas of the continent. A few species belonging to Melanerythrus Stål, Oncopeltus, Scopiastes and Scopiastella have narrow distribution ranges.

The Orsillinae are a cosmopolitan subfamily comprising 29 genera and 255 species (Slater 1964a; Slater & O'Donnell 1995). More than half of the world's orsillines are restricted to the Hawaiian islands (Usinger 1942; Schuh & Slater 1995). Ashlock (1967) monographed the subfamily and gave a dispersalist account of the biogeography of the group. The Orsillini are found in all major zoogeographic regions and are quite distinctly divided into Eastern and Western Hemisphere genera. The Metrargini are confined to the Western Hemisphere. The Nysiini are primarily found in the Eastern Hemisphere, although the nominotypical genus, Nysius Dallas, has a cosmopolitan distribution.

The Orsillinae are represented in Australia by three tribes, Lepionysiini, Orsillini and Nysiini, four genera and 12 species. The Lepionysiini is a monotypic endemic tribe: Lepionysius ashlocki Štys and L. grossi Ashlock are known from temperate Australia. The Nysiini is represented by eight species of Nysius. Four Nysius species are restricted to either Christmas Island and/or Cocos (Keeling) Island. The ubiquitous pest species, N. vinitor Bergroth and N. clevelandensis Evans, are endemic to Australia. Nysius pacificus China occurs in northern Queensland and extralimitally in Melanesia and the Oriental Region. The Orsillini is represented by two monotypic endemic genera: Austronysius sericus Ashlock is confined to the south-western corner of Western Australia; and Eurynysius meschioides Ashlock is known from subtropical Queensland to the gulfs region of South Australia. Malipatil (2010) revised Australian species of Nysius Dallas, including the description of two new species, and a new monotypic genus Reticulatonysius .

Sweet (1960, 2000) summarised the biology of Lygaeidae with particular reference to their economic importance. A few of lygaeine and orsilline species are pests. Lygaeids are generally considered to be seed-feeders. The majority of species are found on plants; they are often associated with several hosts. Some orsilline and lygaeine species are epigaeic.

The Ischnorhynchinae are known from a broad range of plant families: common associations exist with the Ericaceae, Scrophulariaceae and Myrtaceae. Scudder (1962) reported that many Northern Hemisphere species overwinter on conifers. The Holarctic genus Kleidocerys is often found on ericaceous plants, particularly rhododendrons. The Australian species of Crompus are found on shrubby myrtaceous plants, among them species ofCallistemon R.Br., Kunzea Reichb. and Leptospermum J.R.&G.Forst. The biology of other Australian ischnorhynchine species is unknown.

Lygaeinae are most commonly found on plants and are often associated with species belonging to the Asclepiadaceae and Apocyanaceae. The host associations of Australian lygaeines are poorly known, but among those for which hosts are known, polyphagy is common. Graptostethus servus (Fabricius) is an occasional pest species and is known from a broad range of crop plants, including cotton, sunflower, sweet potato, sugarcane and millet. The Australian Lygaeinae include flightless ground-dwelling species (some Melanerythrus species), that probably feed on cast seeds. This habit is found in lygaeines in other parts of the world, such as in South Africa (Slater 1964b; e.g. species of Apterola Mulsant & Rey) and the Palaearctic Region (Péricart 1998; also Apterola). Slater & Sperry (1973), A. Slater (1985) and Péricart (1998) have summarised much of the known information on lygaeine biology. Lygaeinae often have aposematic colouration and are probably associated with Müllerian mimicry complexes involving other pentatomomorphan taxa (A. Slater 1985).

The feeding-behaviour of Orsillinae appears to be more generalised than that of other Lygaeidae. Ashlock (1967) and Schuh & Slater (1995) reported that orsillines feed on vegetative parts of plants, as well as seeds and flowers. Host records indicate that they are often associated with a broad range of often unrelated plant species. The Australian Rutherglen bug, Nysius vinitor, is an economic pest of many crop plants, including citrus, carrots, flax, sunflowers, tomato, tobacco, parsnips, cherries, peaches, potatoes and maize. This species is one of the most abundant true bug species in Australia and is found in a broad range of habitats, mostly in the southern reaches of the continent. Nysius clevelandensis Evans is also a pest species, but in tropical and subtropical regions of Australia. Sweet (2000) summarised information on these pest species and provided a comprehensive reference list.

Diagnosis

The Lygaeidae are elongate to elongate-ovoid insects. The body is mostly impunctate, and is either dark gray-brown (Ischnorhynchinae and Orsillinae) or brightly coloured, contrastingly marked with orange to red and black (many Lygaeinae). The head is porrect. The antennae and labium are 4-segmented. The pronotum has a transverse impression across the calli. The scutellum bears a raised Y-shaped marking. The abdominal spiracles are dorsal in position. Larval dorsal abdominal glands are present between terga IV/V and V/VI. (Slater 1982; Schuh & Slater 1995; Henry 1997)