Family OMANIIDAE

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Family OMANIIDAE

Introduction

The leptopodomorphan family Omaniidae comprises two genera and six species (Henry 2009) and is restricted to the Eastern Hemisphere. Commonly known as intertidal dwarf bugs, omaniids are usually encountered just below the high-tide mark (Cobben 1970).

Omaniids are very small, coleopteriform, and are grey, bluish or dark in colour. They have very large eyes and flattened ocelli. The head has a collar-like vertex region. The pronotum is strongly transverse and quadrate. The metepisternum is shield-like and encloses the coxa. The metathoracic scent glands have four reservoirs with a single median opening. The forewing sometimes has sutures and hind wings are absent. The pretarsus is simple and has two parempodia. The hind legs are saltatorial with setose areas on the inner side of the hind coxae. The male genitalia are characterised by a short, medially cleft pygophore, small club-shaped parameres, and a grasping device on laterotergites II and III. The females have a shield-like ovipositor plate (Kellen 1960, Cobben 1970, Slater 1982).

Cobben (1970) reported that omaniids inhabit solid substrates of coral, volcanic rock or granite with fine cavities, into which they retreat during high-tide. When tides recede, omaniids become active and are found on the moist exposed edges and lower surfaces of rocks and nearby sand. Kellen (1960) gave detailed notes on Corallocoris marksae (Woodward) in the laboratory. Omaniids are predaceous and feed on organisms associated with algae. Woodward (1958) recorded a range of organisms associated with C. marksae, including mites, springtails and small beetles. Schuster (1965) indicated that Omania coleoptera Horváth is found in association with ptiliid beetles and isopods.

Cobben (1970) erected the family, reviewed their morphology and proposed a close relationship between the Omaniidae and the Saldidae. Polhemus (1976) gave a brief summary of omaniids and supported a sister-group relationship with the Saldidae. Schuh & Polhemus (1980) and Polhemus (1985) gave detailed cladistic analyses of the Leptopodomorpha, which included the omaniids. Cobben (1970) proposed an alternative view, with the Omaniidae as the sister-group of the remainder of the leptopodomorphans. Schuh et al. (1987) catalogued the omaniids, giving a full synonymic listing.

The two omaniid genera are Corallocoris Cobben (four species, from Australia, Japan and the Oriental Region) and Omania Horváth (monotypic, O. coleoptrata from Oman). Corallocoris marksae is known from the coastal regions of Queensland, Melanesia, the Oriental Region and as far east as Samoa. The other Corallocoris species are C. nauruensis (Herring & Chapman) from south-eastern Micronesia, C. satoi (Miyamoto) from Japan and C. aldabrae Cobben from the Indian Ocean.