Saturday 24 November 2018

Phyllium yapicum: A new species of Leaf Insect from Yap Island, Micronesia.

Leaf Insects, Phylliidae are a group of Stick Insects, Phasmida, currently known from as far west as the Seychelles, as far east as Fiji, as far north as Tibet and as far south as New Caledonia. Several new species have been described in this group in recent years, but most of these have been cryptic species (i.e. species which so closely resemble other species that they cannot readily be told apart by physical examination, but which are reproductively isolated from them) split from other species with ranges previously presumed to have larger ranges than was actually the case, rather than new populations living in areas where these Insects had not previously been observed.

In a paper published in the journal Insecta Mundi on 31 August 2018, Royce Cumming and Sierra Teemsma of the Montreal Insectarium describe a new species of Pyllid Leaf Insect from Yap Island in Micronesia.

The new species is placed in the widespread genus Phyllium, and given the specific name yapicum, in reference to the island where it was discovered. It is described from a single female specimen, which was collected in 1980 and deposited in the collection of the California Academy of Natural Sciences, where it has remained overlooked until now. The specimen is 73.4 mm in length and yellow and brown in colour, though it is likely to have been a bright green when alive.

Phyllium yapicum. (A) Dorsal view. (B) Ventral view. (C) Thorax side view. Cumming & Teemsma (2018). 

Phyllium yapicum appears to be most closely related to other members of the genus Phyllium from the Philippines, which is unsurprising as this is the nearest area where they have been recorded to date. However, Yap is separated from the Philippines by 1400 km of open ocean, which would seem rather hard for a Leaf Insect to cross, so Cumming and Teemsma suggest that there may be undiscovered species of Phyllium on the islands of Palau or Guam.

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