New species of the myrmecophile Polyplocotes Westwood (Coleoptera: Ptinidae) from South Australia

Six new species of the Australian myrmecophilous ptinid genus Polyplocotes are described from South Australia. Three are from the deserts of central Australia, one from the Franklin Islands in the Great Australian Bight, one from Eyre Peninsula and one from the Riverland region. Morphologically, the majority of these new species are conventional Polyplocotes , but two are less typical. The characters uniting the genus are explored in the discussion, and comparisons are made to related genera. Although the six new species described here have not been observed in the field, the species of this genus are known to be myrmecophilous, and ant – beetle interactions similar to those seen in other spider beetles might occur between these new species and their host ants.     

The rove beetle Drusilla sparsa (Coleoptera: Staphylinidae) is a myrmecophilous species associated with a myrmicine ant,Crematogaster osakensis (Hymenoptera: Formicidae)

The rove beetle genus Drusilla includes some myrmecophilous species. The Japanese species Drusilla sparsa (Sharp, 1874) has been regarded as a non‐myrmecophilous beetle. In Kagawa Prefecture, Shikoku Island, western Japan, however, we often observed that D. sparsa adults were walking in the vicinity of foraging workers of the myrmicine ant Crematogaster osakensis Forel, 1990. The body color of the beetle is similar to C. osakensis as in other myrmecophilous beetles found near the trails of the host ants. To examine whether D. sparsa is myrmecophilous, we investigated the distribution of D. sparsa and C. osakensis in the field, as well as their behavior including prey preference of the beetle in the laboratory. Drusilla sparsa beetles were collected only in sites where C. osakensis ants occurred. When the beetles encountered the ant workers, they bent the abdominal tip toward the ants. The ants licked the abdominal tip, and then the beetles usually walked away. Such behavioral reaction of the ants was not observed when the beetles encountered workers of the formicine ant Nylanderia flavipes (Smith, 1874) that continuously attacked the beetles. Drusilla sparsa preferred to feed on dead workers of C. osakensis even when other ants were available as food, indicating that D. sparsa is a myrmecophilous species associated with C. osakensis. Crematogaster osakensis was frequently found in the stomach in the ant predator, the Japanese treefrog Hyla japonica Günther, 1859. Thus, the significance of body color similarity between the host ants and beetles is not a case of Batesian mimicry.     

Two new myrmecophilous species of the genus Scutacarus (Acari: Prostigmata: Scutacaridae) with world keys to related species groups

In a survey on heterostigmatic mites (Acari: Prostigmata: Heterostigmata) associated with insects including ants in northwestern Iran, two new species of myrmecophilous mites of the genus Scutacarus (Acari: Scutacaridae) were found. They are S. shajariani sp. nov. phoretic on Tetramorium sp. (Hymenoptera: Formicidae) and S. ebermanni sp. nov. phoretic on Messor sp. The mentioned new species belong to groups of species with reduced setae e and h₂, and no setae 4b, respectively. These two new species are described and illustrated, and world keys are provided for respective species groups.     

Species richness and regional distribution of myrmecophilous beetles

Four major hypotheses have been put forward to explain local species richness of commensal or parasitic species. The resource distribution hypothesis predicts that regionally widespread host species are able to support higher local species richness of commensals or parasites. On the other hand, the resource size hypothesis predicts that larger hosts can support more species than smaller hosts, and comparably, the resource abundance hypothesis predicts that hosts that offer more resources are able to support more species. Finally, the resource concentration hypothesis predicts that hosts that occur in high-density patches support higher species richness. In this study, we tested the first three of the above hypotheses with myrmecophilous beetles and their host ants. In addition to species richness of myrmecophilous beetles, we also applied the above hypotheses to explain the distribution of the beetles. Our data are exclusively based on an extensive literature survey. Myrmecophilous beetles live in naturally fragmented environments composed of host ant colonies and they are exclusively dependent on ants. We found that the distribution of the host ants and the colony size of the host ants had a positive effect on both the species richness and the distribution of myrmecophilous beetles. In the same way, we found that myrmecophilous beetle species that are generalists, i.e. have more than one host ant species, and thus have more abundant resources, were more widely distributed than specialist species. Thus, we found support for the hypothesis that resource distribution, resource size and resource abundance have an effect on species richness and on the distribution of species.     

The acoustic repertoire of lycaenid butterfly larvae

Sounds and vibrations play vital roles in intra- and inter-specific communication of many insect taxa, for sexual display, defence and social recruitment. In Lepidoptera, sound production occurs in larvae, pupae and adults and has evolved in response to selection of sexual or defensive traits. About 75% of the 6000 estimated lycaenid butterflies are associated with ants (termed “myrmecophilous species”) and many species produce acoustic emissions during pre-imaginal development. It was initially believed that these acoustic emissions were only produced by myrmecophilous species, but later studies showed that the ability to produce sounds may be universal among this butterfly family. The acoustic repertoire of the late-instar larvae of 12 lycaenid species (Polyommatinae and Lycaeninae), showing different degrees of interaction with ants, was analysed by investigating 12 acoustic parameters measured on the call fundamental unit (pulse). All samples produced species-specific calls whose spectra were characterized by harmonic frequency components. The inter-specific call diversity better reflects the level of association with ants than the taxonomic relationships between species. Our results support the hypothesis that the ability to emit acoustic signals is widespread in lycaenids, and that these emissions play a role in myrmecophilous interactions.     

How an ant decides to prey on or to attend aphids

The following results on the behavior decision making of the antLasius niger toward two species of myrmecophilous aphidsLachnus tropicalis andMyzocallis kuricola on chestnut trees have been found. (1) An individual worker consistently attended only one aphid species, even if her nestmates attended other aphid species on the same tree. (2) The ants preyed less on the aphid species which they attended than on other myrmecophilous aphid species. (3) The ants preyed less on the aphids which had been attended by their nestmates, even if both aphids were the same species. (4) The ants preyed less on aphids which had provided honeydew to their nestmates. (5) The increased aphid density per ant led to an increase in the rate of predation on the introduced aphids by the ants. These results suggest that each worker ofL. niger chooses aphid species to attend from her experience. In addition, the workers can recognize whether an aphid has been attended by their nestmates and whether an aphid has given their nestmates honeydew. Through these processes, each worker decides to attend or to prey on the aphid. As a result, they may realize efficient collective foraging dependent on aphid density per worker.     

Should aphids attract or repel ants? Effect of rival aphids and extrafloral nectaries on ant–aphid interactions

Among plants and herbivores, two types of conflicts occur in relation to mutualism with ants: one is competition for ant mutualism among myrmecophilous herbivores and plants, and the other is the conflict whether to attract or repel ants between myrmecophiles and nonmyrmecophiles that are damaged by ants. We investigated the extent to which two species of aphids (Megoura crassicauda and Aphis craccivora) and extrafloral nectaries on their host plant (Vicia faba var. minor) interact with one another for their relationships with ants. We designed an experiment where ants can choose to visit seedlings colonized by (1) M. crassicauda, (2) A. cracivora, (3) both aphid species, or (4) neither aphid species. Ants preferred A. craccivora to extrafloral nectaries and avoided tending M. crassicauda. We also analyzed the population growth of each aphid when it coexists with (1) ants, (2) the other aphid species, (3) ants and the other aphid species, or (4) neither of them. Under ant-free conditions, we detected an exploitative competition between the two aphid species. The ants had no significant effect on the population of A. craccivora, whereas they had negative effects on the population growth of M. crassicauda by attacking some individuals. When both aphids coexisted, M. crassicauda suffered ant attack more intensely because A. craccivora attracted more ants than extrafloral nectaries despite ant-repelling by M. crassicauda. On the other hand, the ants benefited A. craccivora by eliminating its competitor. To avoid ant attack, aphids may have been selected either to be more attractive to ants than other sympatric sugar sources or to repel the ants attracted to them. We hypothesize that competition among sympatric sugar sources including rival aphids and extrafloral nectaries is a factor restricting aphids to be myrmecophilous. Received: January 17, 2000 / Accepted: July 4, 2000     

Ants andPolyommatus icarus immatures (Lycaenidae) —sex-related developmental benefits and costs of ant attendance

Summary Third and fourth instar larvae and pupae of the facultatively myrmecophilous Palaearctic blue butterflyPolyommatus icarus showed no alteration in developmental time when reared in the presence of two species ofLasius ants. Sex differences were observed in larval growth and pupal weight, with males growing larger and faster. Sex-related differences also occurred in the costs and benefits of ant-attendance. Male pupal masses tended to be larger in individuals associated with ants, and their pupal weight loss was not enhanced by ant attendance. This positive developmental effect of myrmecophily is tentatively attributed to a stimulating influence of ants on caterpillar feeding behavior. In contrast, females associated with ants tended to lose more weight during the pupal stage. Hence there is evidence for developmental benefits, rather than costs, of myrmecophily in maleP. icarus immatures, whereas ant attendance appears to be more costly for females during the pupal stage. These findings are discussed in relation to data on other myrmecophilous lycaenid species. It is suggested that maintaining low-level myrmecophily and its related organs is a comparatively inexpensive evolutionary stable strategy among this butterfly group.     

The influence of ants on patterns of colonization and establishment within a set of coexisting lycaenid butterflies in a south-east Asian tropical rain forest

In Peninsular Malaysia ten species of lycaenid butterflies use leaf flushes or inflorescences of the legume tree Saraca thaipingensis as larval hostplant. Resource partitioning among these species is regulated by a complex mixture of patterns of interaction with ants. Females of obligately myrmecophilous species lay their eggs exclusively on trees colonized by their specific host ants. On trees colonized by weaver ants, only specialist mutualists adapted to these territorial ants are able to survive, while larvae of other species are killed. The formicine ant Cladomyrma petalae, which inhabits hollow twigs of the myrmecophytic hostplant, likewise precludes oviposition by female butterflies. Lycaenid larvae confronted with this ant species never survive, but one concealed feeding species (Jamides caeruleus) escapes removal due to the cryptic life-habits of the larvae. Two facultative myrmecophiles associate in a mutualistic way with a wide and largely overlapping range of ant genera which forage at the extrafloral nectaries of leaf flushes. One species (Cheritra freja) is not myrmecophilous, but is tolerated by all but the most territorial ants. Ant-dependent hostplant selection and egg-clustering characterize the obligate mutualists, whereas facultative myrmecophiles and the non-myrmecophile distribute their eggs singly over appropriate hostplants. Signals mediating caterpillar-ant communication are highly specialized in one obligate myrmecophile (Drupadia theda), but rather unspecific in four other species tested. Altogether our observations indicate that colonization and establishment of lycaenid butterflies on S. thaipingensis trees are governed by specializations as well as opportunistic use of resources (ants and hostplant parts). Therefore, the diversity of this species assemblage is maintained by deterministic as well as stochastic factors.     

Chemical convergence between a guild of facultative myrmecophilous caterpillars and host plants

1. Ants exert strong selective pressure on herbivorous insects, although some caterpillars can live in symbiosis with them using chemical defensive strategies.
2. We investigated the adaptive resemblance of cuticular hydrocarbons (CHCs) in multitrophic systems involving a guild of facultative myrmecophilous caterpillar species (Lepidoptera: Lycaenidae), tending ants (Hymenoptera: Formicidae), and host plants from three families. We hypothesised that the CHCs of the caterpillars would resemble those of their host plants (chemical camouflage).
3. We analysed CHCs using gas chromatography/mass spectrometry. Morisita's similarity index (SI) was used to compare CHC profiles of caterpillar species with different types of ant associations (commensal or mutualistic), ants, and host plants.
4. We found strong convergence between caterpillars' CHCs and plants, especially for commensal species that do not provide secretion rewards for ants. Moreover, we found unexpected chemical convergence among mutualistic (trophobiotic) caterpillar species that offer caloric reward secretions to ants.
5. These results show that the studied caterpillars acquire CHCs through their diet and that they vary according to host plant species and type of ant association (commensalism or mutualism). This ‘chemical camouflage’ of myrmecophilous caterpillars may have arisen as a defensive strategy allowing coexistence with ants on plants, whereas ‘chemical conspicuousness’ may have evolved in the context of honest signalling between mutualistic partners.
6. We suggest the existence of chemical mimicry among myrmecophilous species, especially between mutualistic caterpillars. Cuticular chemical mixtures can play a key adaptive role in decreasing ant attacks and increasing caterpillar survival in multimodal sensory systems.

     

A Diverse Ant Fauna from the Mid-Cretaceous of Myanmar (Hymenoptera: Formicidae)

A new collection of 24 wingless ant specimens from mid-Cretaceous Burmese amber (Albian-Cenomanian, 99 Ma) comprises nine new species belonging to the genus Sphecomyrmodes Engel and Grimaldi. Described taxa vary considerably with regard to total size, head and body proportion, cuticular sculpturing, and petiole structure while all species are unified by a distinct shared character. The assemblage represents the largest known diversification of closely related Cretaceous ants with respect to species number. These stem-group ants exhibit some characteristics previously known only from their extant counterparts along with presumed plesiomorphic morphology. Consequently, their morphology may inform hypotheses relating to basal relationships and general patterns of ant evolution. These and other uncovered Cretaceous species indicate that stem-group ants are not simply wasp-like, transitional formicids, but rather a group of considerable adaptive diversity, exhibiting innovations analogous to what crown-group ants would echo 100 million years later.     

Ant-related oviposition is not associated to low parasitism of the myrmecophilous butterfly Allosmaitia strophius in an extrafloral nectaried shrub

In Lycaenidae-ant mutualisms, ovipositing females select plants based on the presence and/or species of ants in order to maximize survival rates of immatures. The ants are supposed to protect the immatures from parasitoids, but there is large variation in the protection provided. Here, we experimentally investigated whether the occurrence of the facultative myrmecophilous Allosmaitia strophius (the dominant species in our study system) was ant-related. The parasitism rates of immatures collected in the field and reared in the laboratory were also investigated. Stems of the extrafloral nectaried shrub Peixotoa tomentosa were designated as either ant-present (control) or absent (treated). The occurrence of A. strophius on ant-present stems was five times greater than on treated stems. Most eggs and larvae were associated with Camponotus blandus and Ectatomma tuberculatum, two aggressive ant species in the Brazilian savanna. Egg parasitism rate was 9%, and all the parasitized eggs were on ant-present stems. Pupal parasitism on ant-present and ant-absent stems was 25.6% and 7%, respectively. The higher parasitism rate in the presence of ants might also have been density-dependent, because caterpillars were more abundant in ant-present stems. Tropical lycaenids are frequently found in association with patrolling ants. Nevertheless, there is growing evidence that parasitism is higher in the presence of ants, owing to caterpillar's density-dependent effects in plants with ants, and/or to the weak lycaenid-ant associations. This indicates that the offspring of myrmecophilous lycaenids may not benefit, at least in terms of lower parasitism, by living with ants.     

Does the presence of ant nests matter for oviposition to a specialized myrmecophilous Maculinea butterfly?

More than 50% of the lycaenid butterflies have an ant-associated lifestyle (myrmecophily) which may vary from coexistence to specific mutualistic or even parasitic interactions. Ant-related host-plant selection and oviposition has been observed in some myrmecophilous lycaenids. Therefore, it is remarkable that there is no evidence for this behaviour in the highly specialized, obligate myrmecophilous butterflies of the genus Maculinea. In contrast with previous findings, our results provide evidence for ant-related oviposition patterns in Maculinea alcon in relation to the distribution of specific host-ant nests (i.e. Myrmica ruginodis) based on repeated egg counts during the flight period in two populations. We also show that ant-related oviposition can be counterbalanced by intraspecific competition and oviposition deterrency when host plants already carry several eggs. Therefore, the absence of a correlation between egg load and the presence of host-ant nests at the end of the flight period should be interpreted carefully Whether ovipositional cues are obtained either directly (from ants or their nests) or indirectly (from vegetation structure), and whether alternative explanations based on the phenology and growth form of host plants are possible, is discussed.     

A reassessment of the relations in Malaysia between ants (Crematogaster) on trees (Leptospermum and Dacrydium) and epiphytes of the genus Dischidia (Asclepiadaceae) including 'ant-plants'

Three species of epiphytic Dischidia have been investigated in terms of their relationship to ants on trees. Two species, D. parvifolia and D. astephana , are associated with ants and trees in montane areas. A clear association has been found between ants of the genus Crematogaster and the tree Leptospermum flavescens. This relationship is complex and probably both organisms benefit from the association. The ants live in tunnels in the wood of the major branches and the trunk, and the entire tree is occupied by one ant colony. Trees occupied by ants are maintained by the ants substantially clear of epiphytes other than the two species of Dischidia. The potential benefits to the tree and to the ants of this association are noted. The roots of D. astephana and D. parvifolia penetrate into the cavities of these ant nests and presumably gain nutrients from waste in the ant nests. Both Dischidia species are effectively scavenging upon the waste material from the ant-tree association. The leathery dome-shaped leaves of D. astephana are not vital to the development of the scavenging habit as D. parvifolia has lens-shaped leaves, but may offer some advantage to D. astephana by the uptake of nutrients from waste deposited by the ants under the dome-shaped leaves by interception of stem flow and by uptake of gaseous waste. Ants do not nest under these leaves. Seeds of these species of Dischidia are taken by ants into the central woody area of the ant nest where they germinate. Both Leptospermum and Dischidia can be visualized as showing adaptations to a nutient-deficient tropical montane environment. These adaptations are discussed as is the need for reassessment in this genus of the term 'ant-plant', and the need for wider recognition of the 1ant-tree' relationship between Crematogaster and Leptospermum.     

Entedoninae wasps (Hymenoptera, Chalcidoidea, Eulophidae) associated with ants (Hymenoptera, Formicidae) in tropical America, with new species and notes on their biology

Three new species of Eulophidae associated, or presumed to be associated with ants are described: two species of Horismenus Walker and one species of Microdonophagus Schauff. Information on the biology is also included. The two Horismenus species are from Chiapas, Mexico. Horismenus myrmecophagussp. n. is known only from females and is a gregarious endoparasitoid in larvae of the weaver ant Camponotus sp. ca. textor. The parasitoids pupate inside the host larva, and an average of 6.7 individuals develops per host. This is the second time a species of genus Horismenus is found parasitizing the brood of a formicine ant of genus Camponotus. Horismenus microdonophagussp. n. is described from both males and females, and is a gregarious endoparasitoid attacking the larvae of Microdon sp. (Diptera: Syrphidae), a predator on ant brood found in nests of Camponotus sp. ca. textor. The new species of Microdonophagus, Microdonophagus tertius, is from Costa Rica, and known only from the female. Nothing is known about its biology but since another species in same genus, Microdonophagus woodleyi Schauff, is associated with ants through its host, Microdon larva (with same biology as Horismenus microdonophagus), it is possible that also Microdonophagus tertius has this association. A new distributional record for Microdonophagus woodleyi is also reported, extending its distribution from Panama and Colombia to Brazil.     

A new species of the shrew‐mouse,Archboldomys (Rodentia: Muridae: Murinae), from the Philippines

A new species of murid rodent belonging to the ‘shrew‐mouse’ genus Archboldomys is described from Kalinga Province in northern Luzon Island, Philippines. This is the third known species of this endemic Philippine genus. The new species is distinguished from its congeners by consistent differences in adult body size, limb and tail proportions, coloration and texture of the pelage, and cranial and dental dimensions. Members of this genus are small, diurnal rodents that feed mainly on earthworms and other soil invertebrates, and occur in high elevation montane and mossy forests habitats. The new species may be restricted to the northern portion of the Cordillera Central, whereas its congeners occur in widely separated highland areas in other portions of Luzon. The fact that similar distribution patterns are seen for members of other endemic genera suggests that habitat vicariance may have shaped much of the diversification of murid rodents on Luzon.     

Ant–aphid relations in the south of Western Siberia (Hymenoptera: Formicidae; Hemiptera: Aphididae)

Aphids, the main suppliers of energy-rich honeydew, play an important role in the life of ants. However, the data on the trophobiotic ant–aphid associations in the majority of regions are still limited. We present the first data on the ant–aphid relations in the south of Western Siberia. Investigations were carried out in the most typical biotopes of forest-steppe and steppe zones in the territory of Novosibirsk and Kurgan regions (Russia) during 1993–2014. There were revealed 35 species of ants and 198 species of aphids. Detected 456 ant–aphid associations involved 28 ant species and 134 myrmecophilous aphids. Seven ant species were found to consume honeydew of 9 non-myrmecophilous aphids, scraping it from the plant. This behaviour is typical of subdominant and subordinate ants which do not protect their foraging areas. Ants associate with various numbers of aphid species. About 36% of ants attended aphid colonies of less than 5 species. The largest number of myrmecophilous aphids is associated with L. niger (Linnaeus, 1758) (103 species), Formica pratensis Retzius, 1783 (50), Formica rufa group (25–33), F. (Serviformica) fusca Linnaeus, 1758 (26) and F. (S.) cunicularia Latreille, 1798 (27). Different ants play unequal roles in the formation of trophobiotic interactions with aphids. Due to complex territorial and foraging behaviour, including high functional specialization among honeydew collectors, dominant ants of Formica s. str. are one of the leaders in this process. The role of L. niger and Formica ants of the subgenus Serviformica requires further detailed investigation.     

Ant diversity as a direct and indirect driver of pselaphine rove beetle (Coleoptera: Staphylinidae) functional diversity in tropical rainforests,Sabah, Malaysian Borneo

Pselaphinae is a species‐rich beetle subfamily found globally, with many exhibiting myrmecophily—a symbiotic association with ants. Pselaphine–ant associations vary from facultative to obligate, but direct behavioral observations still remain scarce. Pselaphines are speciose and ecologically abundant within tropical leaf litter invertebrate communities where ants dominate, implying a potentially important ecological role that may be affected by habitat disturbances that impact ants. In this study, we measured and analyzed putative functional traits of leaf litter pselaphines associated with myrmecophily through morphometric analysis. We calculated “myrmecophile functional diversity” of pselaphines at different sites and examined this measure's relationship with ant abundance, in both old growth and logged rainforest sites in Sabah, Borneo. We show that myrmecophile functional diversity of pselaphine beetles increases as ant abundance increases. Old growth rainforest sites support a high abundance of ants, which is associated with a high abundance of probable myrmecophilous pselaphines. These results suggest a potential link between adult morphological characters and the functional role these beetles play in rainforest litter as ecological interaction partners with ants.     

Phylogenetic distance of Thelohania butleri Johnston, Vernick, and Sprague, 1978 (Microsporidia; Thelohaniidae), a parasite of the smooth pink shrimp Pandalus jordani, from its congeners suggests need for major revision of the genus Thelohania Henneguy, 1892

Thelohania butleri, a microsporidian that causes mortality and commercial losses in the smooth pink shrimp Pandalus jordani, is of taxonomic interest as a species resembling the poorly studied type species, Thelohania giardi, of the large, polyphyletic genus Thelohania. We examined the ultrastructure of T. butleri to confirm its identity and reconstructed phylogenies using ribosomal DNA to find the relationship of T. butleri with other Thelohania species in crayfish and ants. Light and transmission electron microscopy from specimens collected from the type locality, the Pacific coast of Canada, confirmed the identity and demonstrated a development similar to that of T. giardi, involving a series of binary fissions without formation of a plasmodium. Phylogenetic analyses consistently showed T. butleri to be distantly related to other Thelohania species, and closely related to species from marine decapods within a larger fish-parasitic clade. Together, features such as host group and habitat, developmental morphology, and phylogeny suggest T. butleri may be a closer relative to T. giardi than any other Thelohania species represented by DNA data so far, and thus imply species from crayfish and ants may not belong in this genus. Results also confirm that genus Thelohania and family Thelohanidae are in need of revision.