Family CERATOCOMBIDAE

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Family CERATOCOMBIDAE

Introduction

The Ceratocombidae, a small cosmopolitan dipsocoromorphan family of eight genera and about 52 species (Slater 1982, Zoological Record 1980–1994, Henry 2009) is represented in Australia by one described and numerous undescribed species in the cosmopolitan genus Ceratocombus Signoret. The widely distributed C. australiensis Gross is known from Lord Howe Island, Queensland, and mainland south-eastern Australia as far west as South Australia and Tasmania.

Reuter (1891), in his monograph on the Ceratocombidae, recognised two subfamilies. Lethierry & Severin (1896) catalogued the Ceratocombidae to include the genera Ceratocombus, Pachycoleus Fieber and Dipsocoris Haliday. McAtee & Malloch (1925) revised the Western Hemisphere ceratocombid fauna in the family Cryptostemmatidae. They recognised two genera, Cryptostemma Herrich-Schaeffer and Ceratocombus, and nine species. They noted some morphological similarities with the Anthocoridae but did not distinguish between characters of phylogenetic importance and parallelisms.

Štys (1982) reviewed the world fauna, provided a key to the six genera and recognised two subfamilies. The Trichotonanninae are represented by the Old World (including Madagascar) genus, Trichotonannus Reuter. The Ceratocombinae are divided into two tribes. The primitive Ceratocombini contains Ceratocombus and Leptonannus Reuter, the latter being known from the Nearctic and Neotropical regions, and the tropical parts of the Afrotropical Region. The more derived tribe Issidomimini includes three tropical Old World genera: the Afrotropical genus Muatianvuaia Wygodzinsky, the Oriental Kvamula Štys and the New Guinean genus Issidomimus Poppius. Štys (1982) provided a cladistic analysis of the genera of Ceratocombidae based predominantly on abdominal characters including the male genitalia. Štys (1983a) described a new genus, Feshina, from Zaire. Henry (1988) catalogued the North American fauna which has four species in the genera Ceratocombus and Leptonannus. The global ceratocombid fauna remains largely undescribed, with hundreds of tropical species undescribed (mainly Ceratocombus and Issidomimini), particularly from the Neotropical and Oriental regions and Melanesia (Štys, pers. comm.).

The Ceratocombidae are among the smallest Heteroptera, with most species about 2 mm in length. They have bristle-like setae on the body and appendages. The antennae are 4-segmented, with the first and second segments short, and the third and fourth segments elongate and annulate. The labium is 4-segmented but sometimes appears to be 3-segmented, with the basal segment swollen and weakly sclerotised. The eyes are well developed to reduced, and ocelli are either present or absent. The proepimeron is enlarged and covers the posterior margin of the head. The tarsal formula of adults is 2:2:2, 2:3:3, 3:3:2 or 3:3:3. The pretarsi are variable with parempodia and pulvilli either present or absent. The metapleura are greatly reduced and the metathoracic scent glands open medially on the metasterna. The forewing has a medial fracture along the costal margin. Wing polymorphism is common, with macroptery or brachyptery known. Coleoptery is also known for some non-Australian species, and in such cases the thoracic pleural regions resemble those of the Schizopteridae (Štys 1983b). The male abdomen is often asymmetrical (except in the Ceratocombini) and the male genitalia are usually asymmetrical; in Ceratocombus, however, both are symmetrical. The females have an ovipositor and the spermatheca typically has an oval bulb and a short duct (Štys 1982, 1983a, 1983b, Slater 1982).

Little is known of the biology of the Ceratocombidae. They have been variously recorded from leaf litter, ground debris, rotting wood and the bases of grass clumps (Henry 1988). Ceratocombids are reportedly predators and have been recorded as biting humans incidently. Mebler & Köhler (1992) described the biology of some European Ceratocombus species. Hill (1980) described the known habitats of Ceratocombus australiensis Gross. He reported this species from a variety of forest types, including plantations of the introduced Pinus radiata D. Don, and young and old wet sclerophyll forests. Its habitat requirements are probably more typified by permanent moisture: it occurs in intermittent stream beds, in river gravel, lawns, wet grasslands and wet, montane alpine heath (Hill, pers. comm.).

The Dipsocoridae are a small cosmopolitan family of dipsocoromorphan bugs containing two genera and about 40 species (Slater 1982; Zoological Record 1980–1994). The Australian fauna includes four species of Cryptostemma Herrich-Schaeffer (Hill 1987).

Dipsocorids are small, usually from 2 to 3 mm in length, and dull brown, with the forewings sometimes with a grey sheen. The head is porrect, conical, weakly deflexed, and with macrotrichae. Ocelli are always present in macropterous morphs. The first two antennal segments are short and thick and the third and fourth segments are filiform, with fine, long hair. The labium is squat, at most reaching the prosternum. The forewing is not divided into corium and membrane, and usually has a deep costal fracture, reaching the M vein. Wing polymorphism occurs, although most Cryptostemma species are macropterous. The larvae have four pairs of dorsal abdominal scent gland openings between terga III–IV, IV–V, V–VI and VI–VII. The tarsal formula is 3:3:3, 2:2:3 or 2:2:2. The adult pretarsus has a single parempodium. The number of abdominal spiracles is reduced. The male abdomen and genitalia are highly asymmetrical and complex. The female ovipositor is membranous and reduced (Slater 1982).

Dipsocorids are predaceous and cryptozoic. Carver et al. (1991) indicate that dipsocorids run rapidly, in contrast to the jumping Schizopteridae. Dolling (1991) reports that the British species, Cryptostemma alienum Herrich-Schaeffer, is found in gravel and beneath stones beside streams, and Pachycoleus waltli Fieber lives in Sphagnum Linnaeus and other mosses near water. Southwood & Leston (1959) suggest that the former species can survive long periods of submersion. Hill (1987) indicated that Australian species of Cryptostemma live interstitially in gravel along the margins of streams. Hill (pers. comm.) suggests that Australian Cryptostemma species are also frequently found in flooded rivers. Štys (1990) summarised the habits of west Palaearctic species.

Reuter (1891) included two subfamilies in the Dipsocoridae, the Schizopterina and Ceratocombina; these were later ranked as families (Reuter 1910). Reuter (1910) treated the Schizopteridae and Ceratocombidae as a major division of the Heteroptera, the Trichotelocera. McAtee & Malloch (1925) revised the Schizopterina and Ceratocombina, under the family-group name Cryptostemmatidae, recognising two subfamilies, the Schizopterinae and Cryptostemmatinae, the latter containing the genera Ceratocombus Signoret and Cryptostemma. Emsley (1969) supported the retention of Reuter's Trichotelocera "series". Štys (1970) supported this, as the Dipsocoromorpha, based on characters of the genitalia, spermatheca and abdominal spiracles, the unique antennal structure, plesiomorphic digestive system and the non-heteropterous eggs.

Emsley's (1969) classification recognised the Schizopteridae and Cryptostemmatidae, with the latter equivalent to the Dipsocoridae, but also including Ceratocombus, Hypsipteryx Drake and Seychellesanus Distant. Štys (1970) raised the former two genera to family level, and transferred Seychellesanus to the Schizopteridae. He restricted the Dipsocoridae to include Cryptostemma Herrich-Schaeffer and Pachycoleus Fieber which are characterised by a narrow, non-inflated propleuron and a deep costal fracture. Richards & Davies (1977) include the ceratocombids in the Dipsocoridae but this is not presently accepted by other authors.

Lethierry & Severin (1896) catalogued the dipsocorids in the Ceratocombidae. Henry (1988) catalogued the North American fauna, which contains two species of Cryptostemma. Wygodzinsky (1948, 1950, 1955) and Štys (1977) described species from various parts of the world. Hill (1987) described four species from south-eastern Australia, including Tasmania. Three of these species were taken at one site adjacent to the Mongarlowe River in New South Wales. He also indicated that undescribed species exist in collections from northern Queensland, south-eastern Queensland, northern New South Wales and the Snowy Mountains. Štys (pers. comm.) reports that many tropical species, mainly taken at light, remain to be described.