Family ENICOCEPHALIDAE

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Family ENICOCEPHALIDAE

Introduction

The Enicocephalidae, or unique-headed bugs (sometimes referred to as gnat bugs), are a cosmopolitan family which is most diverse in the tropics and subtropics. The family is also known from cool temperate regions in both hemispheres, extending in the south to Crozet Island (Carver et al. 1991). Worldwide, the family comprises 55 genera and 405 species (Slater 1982; Wygodzinsky & Schmidt 1991; Zoological Record 1980–1994; Henry 2009).

Enicocephalids are small to medium sized bugs, with elongate bodies ranging in length from 1 to 17 mm. The head is long, subcylindrical, constricted transversely, usually bilobed, and often with a distinct post-ocular globose lobe. The eyes are distinct and two ocelli are present on the post-ocular lobe. The antennae and labium are 4-segmented. The pronotum is usually divided into three lobes by two transverse constrictions and is widest at the base. The forewings are homogeneous, with a simple venational pattern which is often divided into cells. Wing polymorphism occurs and macropterous, micropterous and apterous species are known. Wing shortening is often accompanied by loss of ocelli, reduction in eye size and modification of pronotal shape. Enicocephalids have omphalium metathoracic scent glands, which often have the orifices reduced. The forelegs are raptorial, usually incrassate, and the tibiae are usually dilated apically and variously produced, with plate-like projections, spurs, bristles or tubercles. The foretarsi are either 1 or 2-segmented and bear one or two claws. The middle and hind tarsi are 2-segmented. The external genitalia are simple, and the male ninth abdominal segment is capsule-like; parameres are either present or absent (Usinger 1932, Jeannel 1942, Villiers 1958, Slater 1982, Wygodzinsky & Schmidt 1991).

The biology of the Enicocephalidae has been reviewed by Usinger (1932, 1945), Jeannel (1942), Carayon (1950, 1951), Usinger & Wygodzinsky (1960) and Wygodzinsky & Schmidt (1991). Enicocephalids are primarily predators of soft-bodied arthropods, particularly springtails and symphylans. Carayon (1951) recorded them as entomophagous and omnivorous. They are usually found in forest litter, under stones, in rotten logs, and sometimes under bark or at the bases of leaf sheaths. Usinger (1939) and Villiers (1960) reported that some enicocephalids are associated with ants. The Australian species, Oncylocotis tasmanicus (Westwood), feeds on the pupae and larvae of the ant, Pheidole tasmaniensis Mayr, and eggs or newly hatched young of the spider, Trachycosmus sculptilis Simon (Hickman & Hickman 1981). Enicocephalids are known to swarm, sometimes with thousands of individuals involved (Usinger 1945). These swarms are nuptial flights that occur mostly at dusk (Štys 1981b).

Jeannel's (1942) classification of the Enicocephalidae contained two subfamilies: Aenictopecheinae (as Aenictopechitae) and Enicocephalinae (as Henicocephalitae). He subdivided the Enicocephalinae (sensu Enicocephalidae in the Catalogue) into three tribes: the Systelloderini, Phthirocorini and Enicocephalini. Villiers (1958) adopted this system with minor adjustments. Štys (1970), in a study of the classification of the Enicocephalidae, considered the subdivisions artificial. Štys (1989) revised the suprageneric classification of the Enicocephalidae, recognising five subfamilies: the Phallopiratinae (Phallopirates Štys, Oriental Region); Phthirocorinae divided into the Monteithostolini (Monteithostolus Štys and Ciucephalus Štys, New Caledonia) and Phthirocorini (Phthirocoris Enderlein, New Zealand and Crozet Island, Phthirocorisella Štys, New Guinea); Enicocephalinae divided into the Enicocephalini (cosmopolitan tribe containing many genera (Štys 1978) and Systelloderini (Systelloderes Blanchard, cosmopolitan); Alienatinae (Alienates Barber, southern Nearctic and Neotropical regions); and Megenicocephalinae (Megenicocephalus Usinger, Oriental Region).

Štys (1989) elevated the aenictopecheids to family level on the basis of male and female genitalia, and this arrangement is followed by Carver et al. (1991), and in the Catalogue. Alternatively, Wygodzinsky & Schmidt (1991) maintained the Aenictopecheinae as a subfamily of the Enicocephalidae, recognising them as the most primitive element in the New World enicocephalid fauna. The Enicocephalidae plus the Aenictopecheidae are generally accepted as the most basal infraorder of the Heteroptera, the Enicocephalomorpha (Schuh 1979, 1986), excluding the peloridiids (cf. Carver et al. 1991).

Taxonomic works of importance include the revision by Usinger & Wygodzinsky (1960) which includes two genera, Nesenicocephalus Usinger and Oncylocotis Stål, and five species of Micronesian enicocephalids. Štys (1981a) erected a new subfamily for the New Caledonian species Monteithostolus genitalis Štys. Villiers (1958, 1969) revised the Madagascan and African enicocephalid fauna. Štys (1968) reviewed the nomenclature and species combinations of the Afrotropical Enicocephalidae. Štys (1970) revised the Palaearctic fauna, recognising four genera and nine species. Kritsky (1976, 1977, 1978, 1979) and Wygodzinsky & Schmidt (1991) revised much of the New World enicocephalid fauna. The first world catalogue of the Enicocephalidae was provided by Lethierry & Severin (1896), who recognised one genus and 12 species. Štys (1978) gave an annotated list of the genera of the world Enicocephalidae (including the Aenictopecheidae). Froeschner (1988) catalogued the North American fauna which contains four genera and nine species. Štys (1995) gave the diagnoses for the infraorders and families and provided the keys for subfamilies. Later he (Štys 2002) gave the generic key with some taxonomic changes.