Family STENOCEPHALIDAE

Museums

Museum list

Regional Maps

Family STENOCEPHALIDAE

Compiler and date details

15 February 2002

Introduction

The Stenocephalidae are a small family of coreoid bugs found in the Eastern Hemisphere, mostly in tropical and subtropical regions. The greatest species diversity occurs in the Afrotropical Region. The intrafamilial taxonomy of stenocephalids is polemical. Moulet (1995a, 1995b) recognised a single genus (Dicranocephalus Hahn) and 16 species. Other workers have recognised two genera (also Psotilnus Stål) and 30–36 species (Lansbury 1965, 1966; Schuh & Slater 1995; Tshernova 1996; Brailovsky et al. 2001). The Australian fauna comprises a single species of Dicranocephalus (Brailovsky et al. 2001).

Latreille (1825) first recognised the stenocephalids as a family-group. Most early authors followed this arrangement (e.g. Dallas 1852; Douglas & Scott 1865). Stål (1872) and other subsequent workers (e.g. Puton 1881) considered the stenocephalids as no more than a tribe of the Alydidae (as Coreidae: Alydinae: Stenocephalaria or Stenocephalini). Scudder (1957) in a landmark study on the systematic position of Dicranocephalus established conclusively the family ranking of stenocephalids. The family ranking has been accepted by all modern workers (Štys 1961, 1964; Schaefer 1964, 1981; Lansbury 1965, 1966; Moulet 1995a, 1995b; Schuh & Slater 1995; Henry 1997). The family ranking is followed in the Catalogue.

Many of the aforementioned authors commented on the annectent position of the Stenocephalidae relative to the Coreoidea and Lygaeoidea. Scudder (1957) indicated that the spermatheca was lygaeoid-like and the salivary glands were coreoid in their anatomy. Schaefer (1964) regarded the Stenocephalidae as basal in the Coreoidea, although he found that a number of character states were shared with members of either the Lygaeoidea or Pyrrhocoroidea. For example, the laciniate ovipositor occurs in the Stenocephalidae, Largidae (Pyrrhocoroidea) and Lygaeoidea. Štys (1964) and Schaefer (1975, 1981) confirmed the coreoid placement of stenocephalids and established a close relationship between the Stenocephalidae and Hyocephalidae. Henry (1997) proposed the Coreoidea as a monophyletic group and confirmed the Stenocephalidae and Hyocephalidae as sister-taxa.

Lansbury (1965, 1966) provided the first modern treatment of the family, recognising two genera (Dicranocephalus and Psotilnus) and 36 species (including four as incertae sedis). This work included an appraisal of morphological characters and detailed taxonomic descriptions. Lansbury also recognised further subdivision of Dicranocephalus into informal species-groups, based mostly on colour characters, including those of the connexiva. This arrangement was not considered to have phylogenetic significance and did not comply with Scudder's (1957) division of Dicranocephalus into two species-groups based on spermathecal types. Neither of these authors considered Stål's subgeneric division of Dicranocephalus as having merit. Moulet (1995b) alone has synonymised the genus Psotilnus with Dicranocephalus.

Species concepts within the Stenocephalidae have been the subject of recent debate. Moulet (1995a, 1995b) departed radically from previous classifications, and by introducing considerable synonymy recognised just 16 species of Dicranocephalus. Tshernova (1996) rejected Moulet's classification, and restored the valid species status of many stenocephalid available names. Much of the controversy surrounds the identity of D. agilis (Scopoli), alternatively a species complex or a broadly distributed polymorphic species.

The Stenocephalidae have long been known to occur in Australia (Woodward et al. 1970; Carver et al. 1991), but until recently the known taxon was undescribed. Brailovsky et al. (2001) described this new species, Dicranocephalus aroonanus Brailovsky, Barrera, Göllner & Cassis, an endemic species from the interior arid regions of Australia, in Queensland, South Australia, Western Australia and the Northern Territory. Brailovsky et al. (2001) reported that this species belongs to the D. caffer species-group sensu Lansbury, and is closely related to the Afrotropical species, D. caffer (Dallas).

Significant works on extralimital Stenocephalidae include Linnavuori (1978—Sudan, 1987a—west and central Africa, 1987b—Iraq and Kuwait), Ahmad et al. (1979—Pakistan, India and Bangladesh), Phelivan (1981—Turkey), Chernova (1988—former USSR), Ren (1990—China), Göllner-Scheiding (1996—southern Africa, 2000—Namibia), Tshernova (1996—east Palaearctic), and Moulet (1993—Afrotropical Region, 1995a—Mediterranean).

The biology of the Stenocephalidae is not well understood. Lansbury (1965) reviewed their biology, and included information on host plants, eggs and oviposition, and overwintering behaviour. Stenocephalids are known to be phytophagous on higher plants, particularly of plant species belonging to the Euphorbiaceae (mostly Euphorbia Linnaeus species). Some species are polyphagous and feed on a wide range of hosts belonging to the families Berberidaceae, Cupressaceae, Ericaceae, Euphorbiaceae, Pinaceae and Rosaceae (Moulet 1995a). Females oviposit on plant surfaces. European species are known to overwinter under stones.

Nothing is known of the biology of the Australian species, D. aroonanus. All specimens have been captured at light in arid regions and no host information has been recorded.

Diagnosis

Stenocephalids are elongate and medium-sized species. The body is brown to yellowish-brown. The head is elongate and subtriangular. The ocelli are present and placed near the pronotum. The paraclypeal lobes are pointed and convergent anteriorly. The bucculae are short and explanate. The antennae are 4-segmented. The pronotum is trapeziform. The membrane of the hemelytron has a large and a small basal cell from which a number of longitudinal veins emanate. The metathoracic glands are present. The abdominal spiracles are ventral in position. The abdominal trichobothria of sternites V and VI are placed laterally. The female abdominal sternite VII is divided and the ovipositor is laciniate (third valvulae absent). The spermatheca is sclerotised with a spherical apical bulb. The male pygophore has a median projection and the genital opening is dorsal in orientation. The phallosoma is broad with conjunctival appendages. The dorsal abdominal glands open between terga IV/V and V/VI. (Scudder 1957; Schaefer 1964, 1981; Lansbury 1965, 1966; Slater 1982; Schuh & Slater 1995; Henry 1997)