Dicranocentrus halophilus Mari Mutt, 1985

Greenslade, Penelope, 2008, Correction to the identification of a pioneer species of Collembola found on Anak Krakatau in 1931, Zootaxa 1846, pp. 59-60 : 59

Dicranocentrus halophilus Mari Mutt, 1985

Type locality. Papua New Guinea, Lae (tidal debris).

Material examined. Indonesia: Krakatau, Anak Krakatau, 26.ii.31, W.S.Bristowe coll. ( Mesira calolepis Börner , det. H.Womersley), 1 ex. ( SAMA).

A full description of the species is given in Mari Mutt (1985). This record extends the known distribution of this species about 4,500 km to the west.

Mari Mutt (1985) described a second marine littoral species, Dicranocentrus littoreus , from the Philippines at the same time as D. halophilus . He noted that the two species form a group with characters that differ from other species in the genus in having an elongated head to the mandible, a unique claw structure, enlarged setae on third labral row, large S shaped setae on the dental lobes, apically sharply pointed, ciliated setae on the furcula, no mucronal spine and reduced head and body chaetotaxy, in particular in lacking macrochaetae on abdominal segment I.

More recently, two other species with the same characters have been collected from marine littoral habitats, one from Sulawesi and the other from Australian coral cays in the Coral Sea ( Greenslade 2007). The two new species will be described in a later publication. These new records suggest that a new genus should be erected to accommodate the four similar marine littoral species.

Dicranocentrus halophilus (together with one beetle, three spider, one moth, two ant and a mosquito species) was one of the first arthropod species to be recorded from Anak Krakatau after the 1929 eruption, being found only two years after the island first appeared and once it became cool enough for colonisation by invertebrates ( Bristowe 1931). Womersley (1932), quoting Bristowe’s unpublished field notes, stated that a large amount of drift material had washed up on the beach where the animal was found and it was this that presumably carried the springtails to the island. The presence of a marine littoral species, such as D. halophilus , in large numbers on Anak Krakatau in 1931, before any vegetation had established, is not surprising as marine littoral habitats are stable and predictable over long time periods. The correct identification of this species is important for the light it sheds on dispersal mechanisms and the characteristics of early colonisers of newly emerged landmasses, as well as on the processes involved.