Biogeography of Timor and Surrounding Wallacean Islands: Endemism in Ants of the Genus Polyrhachis Fr. Smith

The Ants (Hymenoptera, Formicidae) of Sri Lanka: a taxonomic research summary and updated checklist

An updated checklist of the ants (Hymenoptera: Formicidae) of Sri Lanka is presented. These include representatives of eleven of the 17 known extant subfamilies with 341 valid ant species in 79 genera. Lioponeralongitarsus Mayr, 1879 is reported as a new species country record for Sri Lanka. Notes about type localities, depositories, and relevant references to each species record are given. Accounts of the dubious and some undetermined species from Sri Lanka are also provided. 82 species (24%) are endemic whereas 18 species that are non-native to Sri Lanka are recorded. The list provides a synthesis of the regional taxonomical work carried out to date and will serve as a baseline for future studies on the ant fauna of this biodiversity hotspot.

Seven new species of Trigonopterus Fauvel (Coleoptera, Curculionidae) from the Tanimbar Archipelago

Based on recent fieldwork, the hyperdiverse weevil genus Trigonopterus Fauvel is recorded for the first time from the Indonesian Tanimbar Archipelago, halfway between Australia and Western New Guinea. All seven species discovered on Tanimbar are new to science, and described here: Trigonopterus atuf sp. nov., T. kumbang sp. nov., T. laratensis sp. nov., T. porg sp. nov., T. selaruensis sp. nov., T. tanimbarensis sp. nov., and T. triradiatus sp. nov. The new species are authored by the taxonomists-in-charge, Raden Pramesa Narakusumo and Alexander Riedel. This fauna appears discordant and established by relatively recent dispersal from New Guinea and other Moluccan islands.

Evolutionary and biogeographic history of the black fly Simulium wayani (Diptera: Simuliidae) on the island of Timor

A recently described species of black fly, Simulium wayani Takaoka and Chen, from the island of Timor was chromosomally mapped to provide insights into its evolutionary and biogeographic history. The morphologically based species status of S. wayani is supported by a suite of fixed chromosomal rearrangements and unique sex chromosomes derived primarily from a large pool of polymorphisms in the S. ornatipes complex in Australia. The banding patterns of its polytene chromosomes indicate that S. wayani is closely related to a pair of homosequential cryptic species (S. norfolkense Dumbleton and S. ornatipes cytoform A2) in the S. ornatipes Skuse complex on mainland Australia; all three species uniquely share the same amplified band in their chromosomal complement. The low level of polymorphism and heterozygosity in S. wayani, relative to Australian populations of the S. ornatipes complex, suggests few colonization events from the larger land mass.

Ants of Ambon Island - diversity survey and checklist

The present checklist of ants (Hymenoptera: Formicidae) of Ambon is the first comprehensive overview of ant species recorded on the island during the last 150 years. The species list is based on literature and museum collections’ records combined with data from our field survey in 2010. In total, there are 74 ant species and subspecies representing 34 genera and six subfamilies known from Ambon. Five of the species found in undisturbed forest were exotic and indicate the overall habitat degradation on the island. The largest proportion of Ambon ant fauna are species with affinities to the Oriental region and species of Oriental-Austro-Melanesian origin. At least 20% of the species are regional endemics. In comparison to other islands in the region, the Ambon fauna seems more diverse and better sampled; however it is clear that a large part of it still remains to be described.

Compound eye adaptations for diurnal and nocturnal lifestyle in the intertidal ant, Polyrhachis sokolova

The Australian intertidal ant, Polyrhachis sokolova lives in mudflat habitats and nests at the base of mangroves. They are solitary foraging ants that rely on visual cues. The ants are active during low tides at both day and night and thus experience a wide range of light intensities. We here ask the extent to which the compound eyes of P. sokolova reflect the fact that they operate during both day and night. The ants have typical apposition compound eyes with 596 ommatidia per eye and an interommatidial angle of 6.0°. We find the ants have developed large lenses (33 µm in diameter) and wide rhabdoms (5 µm in diameter) to make their eyes highly sensitive to low light conditions. To be active at bright light conditions, the ants have developed an extreme pupillary mechanism during which the primary pigment cells constrict the crystalline cone to form a narrow tract of 0.5 µm wide and 16 µm long. This pupillary mechanism protects the photoreceptors from bright light, making the eyes less sensitive during the day. The dorsal rim area of their compound eye has specialised photoreceptors that could aid in detecting the orientation of the pattern of polarised skylight, which would assist the animals to determine compass directions required while navigating between nest and food sources.

Homing abilities of the Australian intertidal ant, Polyrhachis sokolova

The pressure of returning and locating the nest after a successful foraging trip is immense in ants. To find their way back home, ants use a number of different strategies (e.g., path integration, trail-following) and rely on a range of cues (e.g., pattern of polarised skylight, landmark panorama) available in their environment. How ants weigh different cues has been a question of great interest and has primarily been addressed in the desert ants from Africa and Australia. We here identify the navigational abilities of an intertidal ant, Polyrhachis sokolova that lives on mudflats where nests and foraging areas are frequently inundated with tidal water. We find that these solitary foraging ants rely heavily on visual landmark information for navigation but they are also capable of path integration. By displacing ants with and without vector information at different locations within the local familiar territory we created conflicts between information from the landmarks and the path integrator. The homing success of full-vector ants, compared to the zero-vector ants, when displaced 5 m behind the feeder indicate that vector information had to be coupled with landmark information for successful homing. To explain the differences in the homing abilities of ants from different locations we determined the navigational information content at each release station and compared it to that available at the feeder location. We report here the interaction of multiple navigation strategies in the context of the information content in the environment.