Family GEOCORIDAE

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Family GEOCORIDAE

Compiler and date details

15 February 2002

Introduction

The Geocoridae are a cosmopolitan family of lygaeoid bugs comprising 25 genera and 274 species (Slater & O'Donnell 1995, Slater 1999; Zoological Record 2000–2001, Henry 2009). The Australian fauna includes four genera and 20 species.

Baerensprung (1860) first recognised the group (Geocorinae sensu lato) at suprageneric level. Montandon (1913) recognised three tribes: Germalini, Geocorini and Henestarini. Bergroth (1921) erected the Psammiini as a geocorine tribe for two Eastern Hemisphere genera. Slater (1964) at first accepted the aforementioned status and position of Psammiini, but later indicated that its systematic position was uncertain (Slater & Sweet 1965).

Henry (1997) raised the geocorids to family level in a review of lygaeoid relationships. He recognised the Geocorinae + Bledionotinae (including Pamphantini) + Henestarinae as a monophyletic group based on the presence of reniform eyes, posteriorly curved abdominal sutures in larvae, and the helicoid process of the male phallus.

Slater (1999) largely accepted this arrangement, but raised the Pamphantini to subfamily. He allocated the pamphantines to three tribes: the nominotypical tribe, and two new tribes, the Cattarini and Epipolopini. He questioned the position of the Bledionotinae in the Geocoridae because of abdominal spiracle and spermathecal features, but maintained them within the family pending further study. Accordingly, the classification used in this Catalogue is as follows: Geocoridae: Geocorinae, Pamphantinae (Pamphantini, Cattarini, Epipolopini), Bledionotinae and Henestarinae.

Scudder (1963) combined the bledionotines and pamphantines, removing them from the Rhyparochromidae, and suggested similarities between this group and geocorines. Seidenstucker (1964) and Péricart (1998) maintained the Bledionotinae as a separate subfamily within the Lygaeidae sensu lato. Péricart (1998) also maintained the Henestarinae as a separate subfamily with affinities to geocorines.

The Geocorinae comprise 13 genera and 233 species and have a cosmopolitan distribution, although most taxa are found in the Eastern Hemisphere. The majority of species belong to the nominotypical genus Geocoris Fallén (169 species) and Germalus Stål (37 species). The remaining genera are composed of five or less species and six genera are monotypic.

The Australian geocorine fauna includes three genera and 19 species. Geocoris is represented in Australia by nine species, most of which have tropical distribution; two species are known only from Christmas Island. Germalus contains five species, four of which are found in tropical Australia. Germalus victoriae Bergroth is broadly distributed across Australia and is extremely variable in colour; in this Catalogue we propose three new synonymies for this species based on an examination of the types. Stylogeocoris is represented by five species, three of which are broadly distributed. Malipatil (1994) revised the Australian species of Geocoris and Stylogeocoris, providing generic diagnoses and descriptions. He suggested that Geocoris is poorly defined and probably represents several distinct genera. He did not adhere to subgeneric arrangements of the genus (e.g. Puton 1875; Linnavuori 1972; accepted by Slater & O'Donnell 1995) and none is followed in this Catalogue. Significant extralimital works concerning the Geocorinae include Readio & Sweet (1982—Nearctic Region) and revisions of the Palaearctic fauna by Kerzhner (1979—former USSR) and Péricart (1998—western Palaearctic). Henry (2005) revised the New World genus Epipolops Herrich-Schaeffer.

The Pamphantinae comprise nine genera and 34 species. The group is found only in the Western Hemisphere, with the exception of the Australian endemic species, Austropamphantus woodwardi Slater. This species is restricted to the Iron Range district of Queensland and is known only from the type locality (Slater 1981). The Pamphantini comprises six genera and 18 species, with most species restricted to the Neotropical Region (Brailovsky 1989, 1990; Slater & O'Donnell 1995; Slater 1999). The Cattarini and Epipolopini each contain nine species and are restricted to the northern countries of South America (Scudder 1963; Slater 1999; Slater & Henry 1999).

The Bledionotinae comprise a monotypic ant-mimetic genus found from the eastern Mediterranean to Afghanistan (Péricart 1998). The Henestarinae contain three genera and 16 species, most of which occur in the Palaearctic and Afrotropical Regions; the monotypic Argentinian genus Coriantipus Bergroth is the exception. Zheng & Dong (1996) discussed the relationships of henestarines, and Péricart (1998) revised the eastern Palaearctic fauna.

Sweet (2000) summarised the biology of geocorids. Most knowledge concerns the bionomics of Geocoris species of economic importance. Unlike most other lygaeoids, Geocorinae are generalist predators, feeding on small arthropods. Sweet (1960) reported likely omnivory for some geocorines, based on successful rearing of species on sunflower seeds under laboratory conditions. Cobben (1978) speculates that complete development for geocorines may require supplemental plant food. Eubanks & Denno (2000) reported that the presence of high-quality plant nutrients reduced the intake of arthropod prey by a Geocoris species.

Geocorines are 'up-on-plants' and some species appear to have definitive host plants (Péricart 1998). They are considered to be among the most important natural enemies in agroecosystems, such as cotton plantations in the United States (Hagler & Cohen 1991). Sweet (2000) and others have promoted geocorids as potentially valuable biological control agents because of their energetic predatory behaviour.

The biology of the Australian species is poorly understood and only a few host plant records are known. Geocoris lubrus Kirkaldy is known from monocot and dicot crop plants, such as rice, sorghum, sunflower, watermelon, cotton, lucerne and potato. Stylogeocoris elongatus Distant has been recorded feeding on the Lantana Lacebug, Teleonemia scrupulosa Stål.

Species of the other geocorid subfamilies are assumed to be phytophagous and are probably granivorous. Nothing is known of the biology of Bledionotinae, aside from their ground-dwelling habit. Henestarinae are apparently granivorous, 'up-on-plants', and are often associated with halophilic plants (Péricart 1998). Pamphantinae are arboreal and are known only from rainforest canopies of the Neotropics (Slater 1998, 1999, Slater & Henry 1999). The biology of the Australian pamphantine species, Austropamphantus woodwardi, is unknown.

Diagnosis

Geocoridae are either elongate, elongate-ovoid to oval (Geocorinae, Henestarinae), elongate-ovoid with bizarre modifications (Pamphantinae: Epipolopini) or with ant-mimetic fascies (Bledionotinae, Pamphantinae: Cattarini, Pamphantini). The eyes are often reniform and sometimes stalked. Ocelli are present. The antennae and labium are 4-segmented. Abdominal spiracles II–IV are dorsal and spiracles V–VII ventral. The larvae have anteriorly curved dorsal abdominal sutures. (Scudder 1963; Malipatil 1994; Schuh & Slater 1995; Henry 1997)