Australian glow-worms (Diptera: Keroplatidae: Arachnocampa spp.) : disbtribution, diversity, identity and management (2004)

The genus Arachnocampa is restricted exclusively to Australasia. In many regions ofnAustralia, glow-worm (Arachnocampa spp.) tourism contributes significantly to theninternational tourism economy. However, little is known about the insects around whichnthis industry is based. The primary objectives of this study were to identifynArachnocampa distribution in Australia and identify species based on geographic,nreproductive, genetic and morphological characters. By highlighting the importance ofncorrect species identification, effective management guidelines can be implemented fornspecific species found to be at risk in their natural habitat.n n Specific habitat requirements (i.e. areas of high humidity), poor Arachnocampandispersal abilities and fragmentation of habitat have led to the current geographic isolationnof Arachnocampa species. Prior to this study, four species of Arachnocampa had beenndescribed, including three species endemic to Australia. However, our understanding ofnArachnocampa spp. Australia-wide is limited, as most published records of occurrenceninclude no taxonomic or biological investigations of the noted populations. PotentialnArachnocampa spp. sites within Australia, not previously documented in the literaturenwere identified based on habitat types within rainforest and caves. From these data, 49nsites were visited, specimens collected, and geographical distribution data was collatednand databased. Eight regional groups were defined based on geographic isolation of theirnspecialised habitat. The results from this study greatly increase the known Arachnocampanspp. distribution range to include the wet tropical rainforest of north Queensland and newnsites through southeast Queensland, New South Wales and Victoria. These regionalngroups are further identified through reproductive isolation experiments (Chapter 3),nphylogenetic analysis (Chapter 4), and morphological characters (Chapter 5) for evidencenof speciation through allopatry.n n Male and female Arachnocampa spp. from the same colony will readily mate innthe laboratory, so mating trials between individuals were used to determine potentialnreproductive isolation between and within regional groups at three levels: (1) intra-colonyn(i.e. samples from the same colony) (n = 8), (2) intra-regional (i.e. samples from thensame geographically distinguished region (defined in Chapter 2), but not within the samencolony) (n = 7), and (3) inter-regional (i.e. samples from geographically separatednregions) (n = 22). The results support geographically based, regional groups as distinct,nreproductively isolated species. All eight intra-colony crosses were successful while onlynone of the 22 inter-regional pairings resulted in mating. However, the eggs from thisninter-regional copulation did not hatch, and subsequent repeats of the cross resulted in nonmate recognition. Twenty-one inter-regional crosses resulted in no matings, indicating anhigh degree of reproductive isolation between allopatric populations. Further intraregionalnseparation was indicated in two of the designated regional groups, namely westnVictoria and east Victoria. Introductions of adults from within the same colonies (intra-colony)nshowed these pairs would readily mate in the laboratory trials, but adults wouldnnot mate with individuals from another colony within the same designated regional groupn(intra-regional), separated geographically by 30, 40 and 70 km respectively. Whilencomprehensive pairings were not possible, the results point to strong allopatric speciation.nChapter 3 discusses allopatry in reference to the biological species concept as an instigatornof the exhibited reproductive isolation between Arachnocampa species.n n To provide phylogenetic evidence supporting species designations, molecularnsequence data from 419 base pairs (bp) of the mitchondrial gene fragment cytochromenoxidase II and 414 bp of the mitochondrial gene fragment 16S rDNA were analysed forn37 Australian populations of Arachnocampa, and two outgroup species, A. luminosa,nfrom New Zealand (north and south island localities) and, Orfelia fultoni, from NorthnAmerica (2 localities). The aligned sequence data were analysed in PAUP usingnparsimony heuristic search algorithms, bootstrapped with 1000 replicates. Phylogeneticnanalysis of standard and combined data sets strongly supports geographically basednregional groupings (Chapter 2) and is largely consistent with results from the reproductivenisolation experiments. Phylogenetically, there was no indication of further differentiationnwithin the west Victoria or east Victoria regional groups, as was indicated throughnreproductive isolation experiments (Chapter 3). The phylogenetic study indicated furtherndelineation within the north Queensland region. Populations from the refugial cavenhabitats in Girraween National Park, southeast Queensland and populations from thenrainforest in Washpool National Park, northern New South Wales, grouped togethernwithin the phylogenies.n n Morphological examinations of life stages of the eight designated regional groupsnwere undertaken to ascertain any exhibited phenotypic differentiation between the groupsnand to identify and describe new species. The existing distinction between the subgeneranArachnocampa and Campara, defined on morphological grounds by Harrison (1966), isnsupported by this study and additional characters are described that further describe thensubgenera. Five new species are described: A. buffaloensis (Victoria); A. tropicus (northnQueensland); A. gippslandensis (east Victoria); A. otwayensis (west Victoria) and; A.ngirraweenensis (southeast Queensland/ northern NSW). Further evidence, derived fromnmating trials and molecular phylogenies, denote further delineation is present withinnpopulations in west Victoria (evidence from reproductive isolation), Tasmania (evidencenfrom genetic variation), north Queensland (evidence from genetic variation) and eastnVictoria (evidence from reproductive isolation and genetic variation). However, thesenpotential species appear to be morpho-cryptic at this level and are not given species statusnin this study. Each newly identified species was described based on characters that clearlyndifferentiate them. Variation of some characters within populations indicated that a degreenof plasticity occurs within this genus. Morphological variation or phenotypic plasticitynwas also evident between cave and rainforest populations within the same regions. Thisnplasticity, however, is hypothesised as being driven by environmental factors rather thanngenetic variation.n n Given the strict habitat requirements of Arachnocampa spp. and their poorndispersal skills, the genus is often found in isolated habitat where many factors can impactnon a colony's sustainability. I identify three key areas of potential Arachnocampa spp.nvulnerability and examine case studies specific to each of these areas. Case Study Aninvestigates the practices of commercial glow-worm tour operators in Australia. Eachnoperator was documented and surveyed to identify their annual tourist numbers and issuesnrelating to biological information including glow-worm threats and sustainablenmanagement. The study found that a high proportion of commercial operators incorporatensubstantial biological information in their tours and address threats to glow-worms,nincluding information on human impacts. The study concluded that commercial glow-wormntourism could potentially lead to increased awareness for visitors and the localncommunities, therefore leading to increased protection for glow-worms and longevity ofnassociated glow-worm tourism in Australia.n n Case Study B identified a new species of parasitoid wasp, found to be infectingnArachnocampa spp. populations in north Queensland. The wasp larva develops andnpupates in the inactive larva of the north Queensland populations, resulting in the glow-worm'sndeath. The overall density of Arachnocampa spp. colonies in north Queenslandnwas lower than other Australian colonies and parasitism is hypothesised as a reason fornthe decreased density. High rates of parasitism (31%) were recorded in larvae collectednfrom north Queensland. Movement of the parasitoid to southern Arachnocampa spp.npopulations could be catastrophic to the multi-million dollar industry surrounding them.nTherefore making tourists and tour operators aware of its potential impacts is of greatnimportance to Arachnocampa spp. survival.n n Case Study C focuses on a small, fragmented colony of Arachnocampa spp.nfound in one sub-alpine cave in Victoria. The population is thought to be unable to survive the harsh climatic changes throughout the year outside the cave, and is thusnrestricted to its current habitat. Isolated habitat was indicated as an important factor fornlisting this species as threatened. An action management plan is included for follow upnafter listing.nnnnnnn