Halobates - Oceanic Insects

Distribution of Sea Skaters

Nils Møller Andersen
Zoological Museum, University of Copenhagen

Ó Copyright, N. M. Andersen & Zoological Museum, University of Copenhagen

Contents

General distribution

Distribution of ocean striders

Literature cited

General distribution

Halobates belongs to the subfamily Halobatinae, essentially an Old World group of water striders (Gerridae). The sister group of the Halobatini (Gerridae - Halobatinae) is the tribe Metrocorini with about 100 limnic species distributed in tropical Africa, continental Asia and adjacent areas of the Palearctic region, and the Indo-Malayan Archipelago. It does not cross Wallace's line except for a few species found in Sulawesi. The genus Asclepios (with three marine species) is confined to South and East Asia. The sister group of Halobates is the monotypic genus Austrobates which is endemic to tropical Australia like the most basal lineage of Halobates (subgenus Hilliella) with three species (Andersen & Weir, 1994a, 1994b).

The majority of the 45 extant species of Halobates are found in the tropical parts of the Indo-West Pacific region, roughly between latitudes 30^o N and 30^o S. H. robustus (endemic to the Galapagos Islands) and the oceanic species H. sobrinus, splendens (eastern Pacific Ocean), and H. micans (Atlantic Ocean, the Caribbean Sea, and eastern Pacific Ocean) are the only sea skaters that occur outside this region (Herring, 1961; Cheng, 1985, 1989).

Andersen (1991) grouped species of Halobates in a number of monophyletic species groups, each showing a characteristic distribution. The two species of the subgenus Hilliella are confined to Australia, as are most species belonging to the Halobates regalis group. Many Halobates species are endemic to single islands or island groups, including H. robustus (Galapagos), H. kelleni (Samoa), H. salotae (Tonga), H. bryani and fijiensis (Fiji), and H. tethys (Mauritius), but a few coastal species are widespread, such as H. hayanus White (Red Sea to New Guinea and Australia), H. flaviventris (East Africa to Vanuatu), and H. hawaiiensis (islands of the Pacific Ocean). For further distributional details, see Checklist and Distribution of Halobates.

Distribution of ocean striders

The widest areas of distribution are found in the oceanic species Halobates micans (all tropical oceans), H. sobrinus  and splendens (East Pacific Ocean), H. germanus (Indian Ocean, West and Central Pacific Ocean) and H. sericeus (Pacific Ocean). In the Pacific Ocean, the last mentioned species is absent from a large area North and South of the equator.

The present distribution of coastal Halobates species more or less coincides with the distribution of reef-building corals and mangrove trees which require a relatively high sea temperature (Andersen, 1998, 1999). The five oceanic species of Halobates occur in tropical and subtropical waters and their occurrence and abundance on any given water mass is apparently controlled by surface water temperatures, with an optimum temperature range for four eastern Pacific species (including H. micans) of 24-28^oC. The absence of Halobates species from the Mediterranean may in part be due to the surface temperature being below 20^o C at certain times of the year whereas the surface temperature of the Red Sea varies between 25 and 30^o C.  

Literature cited

Andersen NM. 1982. The Semiaquatic Bugs (Hemiptera, Gerromorpha). Phylogeny, adaptations, biogeography, and classification. Entomonograph 3: 1-455.

Andersen NM. 1991. Marine insects: genital morphology, phylogeny and evolution of sea skaters, genus Halobates (Hemiptera: Gerridae). Zool. J. Linn. Soc. 103: 21-60.

Andersen NM. 1998. Marine water striders (Heteroptera, Gerromorpha) of the Indo-Pacific: cladistic biogeography and Cenozoic palaeogeography. In Hall R, Holloway JD (eds), Biogeography and Geological Evolution of SE Asia : 341-354.

Andersen NM. 1999. The evolution of marine insects: phylogenetic, ecological and geographical aspects of species diversity in marine water striders. Ecography 22: 98-111.

Andersen NM, Polhemus JT. 1976. 8. Water-striders (Hemiptera: Gerridae, Veliidae, etc.). In Cheng L. (ed.), Marine Insects. North Holland Publ. Co., Amsterdam: 187-224.

Andersen NM, Weir TA. 1994. Austrobates rivularis, gen. et sp. nov., a freshwater relative of Halobates (Hemiptera: Gerridae), with a new perspective on the evolution of sea skaters. Invertebrate Taxonomy 8: 1-15.

Andersen NM, Weir TA. 1994. The sea skaters, genus Halobates Eschscholtz (Hemiptera: Gerridae), of Australia: taxonomy, phylogeny and zoogeography. Invertebrate Taxonomy 8: 861-909.

Cheng L. 1973. Halobates. Ann. Rev. Oceanogr. Mar. Biol. 11: 223-235.

Cheng L. 1985. Biology of Halobates (Heteroptera: Gerridae). Ann. Rev. Ent. 30: 111-135.

Cheng L. 1989. Biogeography and phylogeny of the sea-skaters Halobates. Chin. J. Oceanol. Limnol. 7: 233-239.

Cheng L. 1989. Factors limiting the distribution of Halobates species. In Ryland, J.S. & Tyler, P.A. (Eds.). Reproduction, genetics, and distributions of marine organisms. Fredensborg: Olsen & Olsen: 357-362.

Cheng L, Schulenberger E. 1980. Distribution and abundance of Halobates species (Insecta: Heteroptera) in the eastern tropical Pacific. Fishery Bulletin 78: 579-591.

Herring JL. 1961. The genus Halobates (Hemiptera: Gerridae). Pacific Insects 3(2-3): 223-305.