Seychelles Invertebrates

Introduction

Some 3,000 species of terrestrial invertebrate have been recorded in Seychelles.The majority of these are known from isolated records or from a smallnumber of specimens. Nature Protection Trust of Seychelles hasongoing research programmes evaluating the diversity of invertebrates inthe islands. These projects, mostly undertaken on a voluntary basis,aim to locate species which have not been recorded since their collection100 years ago, to identify sites of special importance for invertebrateconservation and monitor the distribution of introduced species.

NPTS invertebrate research relies upon extensive collections of historicalliterature and a network of taxonomists providing identification and taxonomicreviews. This has enabled the identification of large numbers of speciesnot recorded since the major collection expeditions of 1892-1909 and manynew species.  So far very few islands have been studied and only onelarge island (Silhouette) is being studied indetail.

Rediscoveries

The majority of 'rediscovered' species are small and inconspicuous.One dramatic exception is the Seychelles bee-hawkmoth (Cephonodestamsi). This species was known from a single specimen from Mahéisland in 1911 and was presumed extinct until several individuals were foundon Silhouette in 1997. This large, bright red species appears to belocally abundant but very patchily distributed.  Research into itsdistribution and ecology will re-evaluate its status. Since 1997 furtherdramatic rediscoveries have been made: the Seychelles hummingbird hawkmoth(Macroglossum alluaudi) in 2000 and theSeychelles fineliner damselfly(Teniobasis alluaudi) in 2001. These striking species will bethe focus of major research initiatives in the future.

Fregate island invertebrates

The only conservation measures specifically for invertebrates are the captivebreeding programme for the threatened species from Fregate island. NPTSis working with the Zoological Society of London's Invertebrate ConservationCentre to maintain a viable captivepopulation of Seychelles giant millipede (Sechelleptusseychellarum), giant tenebrionid beetle (Pulposipes herculeanus),Fregate island snail (Pachnodus fregatensis) and Seychelles giantscorpion (Chiromachus ochropus). These are all threatened bybrown rats (Rattus norvegicus) which invaded the island in 1995. Itwas feared that rats will feed on these large invertebrates and as the ratpopulation expanded the invertebrates may have become extinct. Themillipede is found on several other islands but may represent a separatesub-species. The beetle is restricted to Fregate island (historicallyit was also found on Round island near Mauritius and probably on other Seychellesislands) as is the snail. The scorpion is found on other islands inSeychelles but is only abundant on Fregate. All four species areestablished in captivity, ensuring that a reservoir population is maintained.Rats were eradicated from the island in 2000 and invertebrate populationsurveys were carried out by NPTS in 2002. Field work on Fregate byNPTS discovered a new genus of snail in 1999, this species is also in needof conservation.

Taxonomy

A major research programme led by NPTS is the full revision of the taxonomy and conservation status of all Seychelles species. This is producing several scientific publications, the most important of which are the Seychelles fauna monographs.