Breakdown in seasonal dynamics of subtropical ant communities with land-cover change.

Concerns about widespread human-induced declines in insect populations are mounting, yet little is known about how land-use change modifies both the trends and variability of insect communities, particularly in understudied regions. Here, we examine how the seasonal activity patterns of ants-key drivers of terrestrial ecosystem functioning-vary with anthropogenic land-cover change on a subtropical island landscape, and whether differences in temperature or species composition can explain observed patterns. Using trap captures sampled biweekly over 2 years from a biodiversity monitoring network covering Okinawa Island, Japan, we processed 1.2 million individuals and reconstructed activity patterns within and across habitat types. Forest communities exhibited greater temporal variability of activity than those in more developed areas. Using time-series decomposition to deconstruct this pattern, we found that sites with greater human development exhibited ant communities with diminished seasonality, reduced synchrony and higher stochasticity compared with sites with greater forest cover. Our results cannot be explained by variation in regional or site temperature patterns, or by differences in species richness or composition among sites. Our study raises the possibility that disruptions to natural seasonal patterns of functionally key insect communities may comprise an important and underappreciated consequence of global environmental change that must be better understood across Earth's biomes.

Pheidoleklaman sp. nov.: a new addition from Ivory Coast to the Afrotropical pulchella species group (Hymenoptera, Formicidae, Myrmicinae).

In this study the taxonomy of the Pheidolepulchella species group is updated for the Afrotropical region and the new species P.klaman sp. nov. described. It is integrated into the existing taxonomic system by an updated identification key for the whole group and an update of the known distribution ranges of its members. High quality focus stacking images are provided, with X-ray micro-CT scanned digital 3D representations, of major and minor worker type specimens.

Monomorium (Hymenoptera: Formicidae) of the Arabian Peninsula with description of two new species, M. heggyi sp. n. and M. khalidi sp. n.

We present a revised and updated synoptic list of 44 Arabian Monomorium species, including two new species of the M. salomonis species-group: M. heggyi sp. n., and M. khalidi sp. n. We propose the following new synonyms: M. abeillei André (= M. wahibiense Collingwood & Agosti syn. n.); M. areniphilum Santschi (= M. fezzanense Collingwood & Agosti syn. n., = M. hemame Collingwood & Agosti syn. n. = M. marmule Collingwood & Agosti syn. n.); M. bicolor Emery (= M. phoenicum Santschi syn. n.); M. harithe Collingwood & Agosti (= M. najrane Collingwood & Agosti syn. n.); M. niloticum Emery (= M. matame Collingwood & Agosti syn. n.); and M. nitidiventre Emery (= M. yemene Collingwood & Agosti syn. n.). An illustrated key and distribution maps are presented for the treated species. Ecological and biological notes are given when available. The majority of Arabian Monomorium species (24) are endemic to the peninsula. All except one of the remaining species are more broadly ranging Afrotropical and Palearctic species, supporting the view of Arabia as a biogeographical crossroads between these two regions. Monomorium floricola (Jerdon), the sole species of Indomalayan origin, is recorded for the first time from the Arabian Peninsula.

Ants of the Hengduan Mountains: a new altitudinal survey and updated checklist for Yunnan Province highlight an understudied insect biodiversity hotspot.

China's Hengduan Mountain region has been considered one of the most diverse regions in the northern hemisphere. Its stunning topography with many deep valleys and impassable mountain barriers has promoted an astonishing diversification in many groups of organisms including plants, birds, mammals, and amphibians. However, the insect biodiversity in this region is still poorly known. Here, the first checklist of ant species from the Southern Hengduan Mountain region is presented, generated by sampling ant diversity using a wide array of collection methods, including Winkler leaf litter extraction, vegetation beating, and hand collection. 130 species/morphospecies from nine subfamilies and 49 genera were identified. Among them, 17 species from 13 genera represent new records for Yunnan province, and eight species are newly recorded for China. Moreover, we believe 41 novel morphospecies (31% of the total collected taxa) will prove to be new to science. These results highlight the rich ant fauna of this region and strongly support its status as a biodiversity hotspot. The current ant species checklist for the whole of Yunnan Province was updated by recording 550 named species from 99 genera. Taken together, our results suggest that the Yunnan ant fauna still remains under-sampled, and future sampling will likely yield many more species, among them many undescribed ones.

Distal leg structures of the Aculeata (Hymenoptera): A comparative evolutionary study of Sceliphron (Sphecidae) and Formica (Formicidae).

The distal parts of the legs of Sceliphron caementarium (Sphecidae) and Formica rufa (Formicidae) are documented and discussed with respect to phylogenetic and functional aspects. The prolegs of Hymenoptera offer an array of evolutionary novelties, mainly linked with two functional syndromes, walking efficiently on different substrates and cleaning the body surface. The protibial-probasitarsomeral cleaning device is almost always well-developed. A complex evolutionary innovation is a triple set of tarsal and pretarsal attachment devices, including tarsal plantulae, probasitarsomeral spatulate setae, and an arolium with an internal spring-like arcus, a dorsal manubrium, and a ventral planta. The probasitarsal adhesive sole and a complex arolium are almost always preserved, whereas the plantulae are often missing. Sceliphron has retained most hymenopteran ground plan features of the legs, and also Formica, even though the adhesive apparatus of Formicidae shows some modifications, likely linked to ground-oriented habits of most ants. Plantulae are always absent in extant ants, and the arolium is often reduced in size, and sometimes vestigial. The arolium contains resilin in both examined species. Additionally, resilin enriched regions are also present in the antenna cleaners of both species, although they differ in which of the involved structures is more flexible, the calcar in Sceliphron and the basitarsal comb in Formica. Functionally, the hymenopteran distal leg combines (a) interlocking mechanisms (claws, spine-like setae) and (b) adhesion mechanisms (plantulae, arolium). On rough substrate, claws and spine-like setae interlock with asperities and secure a firm grip, whereas the unfolding arolium generates adhesive contact on smooth surfaces. Differences of the folded arolium of Sceliphron and Formica probably correlate with differences in the mechanism of folding/unfolding.

Colonize, radiate, decline: Unraveling the dynamics of island community assembly with Fijian trap-jaw ants.

The study of island community assembly has been fertile ground for developing and testing theoretical ideas in ecology and evolution. The ecoevolutionary trajectory of lineages after colonization has been a particular interest, as this is a key component of understanding community assembly. In this system, existing ideas, such as the taxon cycle, posit that lineages pass through a regular sequence of ecoevolutionary changes after colonization, with lineages shifting toward reduced dispersal ability, increased ecological specialization, and declines in abundance. However, these predictions have historically been difficult to test. Here, we integrate phylogenomics, population genomics, and X-ray microtomography/3D morphometrics, to test hypotheses for whether the ecomorphological diversity of trap-jaw ants (Strumigenys) in the Fijian archipelago is assembled primarily through colonization or postcolonization radiation, and whether species show ecological shifts toward niche specialization, toward upland habitats, and decline in abundance after colonization. We infer that most Fijian endemic Strumigenys evolved in situ from a single colonization and have diversified to fill a large fraction of global morphospace occupied by the genus. Within this adaptive radiation, lineages trend to different degrees toward high elevation, reduced dispersal ability, and demographic decline, and we find no evidence of repeated colonization that displaces the initial radiation. Overall these results are only partially consistent with taxon cycle and associated ideas, while highlighting the potential role of priority effects in assembling island communities.

Taxonomy of Arabian Temnothorax Mayr (Formicidae: Myrmicinae) with description of a new species enhanced by x-ray microtomography.

Temnothorax elmenshawyi sp. n., a new ant species from the Asir Mountains of the southwestern region of the Kingdom of Saudi Arabia, is described based on the worker caste. The new species is a member of the T. exilis species group and is distinguished from the other species included in this group by the impressed metanotal groove, the short, acute and broadly-based propodeal spines, the finely punctate posterior half of cephalic surface, and absence of a median clypeal carina. Despite extensive collecting by the authors at the type locality, only two specimens are available for description, suggesting that this species may be rare and likely endemic to the Asir Mountains. The species description is complemented by still images of volume renderings of a 3D model and a 3D rotation video of the holotype based on x-ray microtomography (micro-CT), allowing remote in-depth examination of the specimen. The virtual micro-CT data is provided as cybertype dataset and freely available online https://doi.org/10.5061/dryad.4gg39k6 , as well as 3D surface model (Sketchfab.com, https://skfb.ly/6HYRz). An updated identification key to the Arabian species is presented.

The cephalic anatomy of workers of the ant species Wasmannia affinis (Formicidae, Hymenoptera, Insecta) and its evolutionary implications.

Despite the ecological significance of ants and the intensive research attention they have received, thorough treatments of the anatomy and functional morphology are still scarce. In this study we document the head morphology of workers of the myrmicine Wasmannia affinis with optical microscopy, µ-computed tomography, scanning electron microscopy, and 3D reconstruction, providing the first complete anatomical treatment of an ant head with a broad array of modern techniques. We discuss the potential of the applied methods to generate detailed and well-documented morphological data sets with increased efficiency. We also address homology problems, particularly in the context of the cephalic digestive tract. According to our analyses the "pharynx" of previous ant studies is homologous to the prepharynx of other insects. We also discuss the phylogenetic potential and functional significance of the observed characters, with internal features such as tentorium and musculature discussed for the first time. Our investigation underlines that detailed anatomical data for Formicidae are still very fragmentary, which in turn limits our understanding of the major design elements underlying the ant bauplan. We attempt to provide a template for further anatomical studies, which will help to understand the evolution of this fascinating group on the phenotypic level.

Skeletomuscular adaptations of head and legs of Melissotarsus ants for tunnelling through living wood.

BACKGROUND: While thousands of ant species are arboreal, very few are able to chew and tunnel through living wood. Ants of the genus Melissotarsus (subfamily Myrmicinae) inhabit tunnel systems excavated under the bark of living trees, where they keep large numbers of symbiotic armoured scale insects (family Diaspididae). Construction of these tunnels by chewing through healthy wood requires tremendous power, but the adaptations that give Melissotarsus these abilities are unclear. Here, we investigate the morphology of the musculoskeletal system of Melissotarsus using histology, scanning electron microscopy, X-ray spectrometry, X-ray microcomputed tomography (micro-CT), and 3D modelling. RESULTS: Both the head and legs of Melissotarsus workers contain novel skeletomuscular adaptations to increase their ability to tunnel through living wood. The head is greatly enlarged dorsoventrally, with large mandibular closer muscles occupying most of the dorsal half of the head cavity, while ventrally-located opener muscles are also exceptionally large. This differs from the strong closing: opening asymmetry typical of most mandibulated animals, where closing the mandibles requires more force than opening. Furthermore, the mandibles are short and cone-shaped with a wide articulatory base that concentrates the force generated by the muscles towards the tips. The increased distance between the axis of mandibular rotation and the points of muscle insertion provides a mechanical advantage that amplifies the force from the closer and opener muscles. We suggest that the uncommonly strong opening action is required to move away crushed plant tissues during tunnelling and allow a steady forward motion. X-ray spectrometry showed that the tip of the mandibles is reinforced with zinc. Workers in this genus have aberrant legs, including mid- and hindlegs with hypertrophied coxae and stout basitarsi equipped with peg-like setae, and midleg femura pointed upward and close to the body. This unusual design famously prevents them from standing and walking on a normal two-dimensional surface. We reinterpret these unique traits as modifications to brace the body during tunnelling rather than locomotion per se. CONCLUSIONS: Melissotarsus represents an extraordinary case study of how the adaptation to - and indeed engineering of - a novel ecological niche can lead to the evolutionary redesign of core biomechanical systems.

Ants of the Monomorium monomorium species-group (Hymenoptera: Formicidae) in the Arabian Peninsula with description of a new species from southwestern Saudi Arabia.

We revise the taxonomy of the myrmicine ants of the Monomorium monomorium species-group for the Arabian Peninsula. Six species are recognized: Monomorium aeyade Collingwood & Agosti, 1996, M. clavicorne André, 1881, M. exiguum Forel, 1894, M. holothir Bolton, 1987, M. mohammedi sp. n., and M. sarawatense Sharaf & Aldawood, 2013. On the basis of the worker caste, we describe Monomorium mohammedi sp. n. from the southwestern region of the Kingdom of Saudi Arabia (KSA). We designate a neotype for Monomorium aeyade Collingwood & Agosti and redescribe and illustrate the worker caste. Furthermore, we provide a worker-based species identification key, distribution maps for the treated species, and ecological and biological notes, if available. Monomorium holothir is recorded for the first time from the KSA. Also, we propose M. clavicorne var. punica Santschi, 1915a as a junior synonym of M. clavicorne, as well as M. dryhimi Aldawood & Sharaf, 2011 and M. montanum Collingwood & Agosti, 1996 to be treated as junior synonyms of Monomorium exiguum.

Taxonomic overview of the hyperdiverse ant genus Tetramorium Mayr (Hymenoptera, Formicidae) in India with descriptions and X-ray microtomography of two new species from the Andaman Islands.

With 600 described species, the ant genus Tetramorium represents one of the most species-rich ant radiations. However, much work remains to fully document the hyperdiversity of this remarkable group. Tetramorium, while globally distributed, is thought to have originated in the Afrotropics and is particularly diverse in the Old World. Here, we focus attention on the Tetramorium fauna of India, a region of high biodiversity value and interest for conservation. We overview Tetramorium diversity in India by providing a species list, accounts of all species groups present, an illustrated identification key to Indian Tetramorium species groups and notes on the Indian Tetramorium fauna. Further, we describe two new species, Tetramorium krishnani sp. n. and Tetramorium jarawa sp. n. from the Andaman Islands archipelago and embed them into currently recognized Tetramorium tonganum and Tetramorium inglebyi species groups. We also provide illustrated species level keys for these groups. Along with detailed species descriptions and high-resolution montage images of types, we provide 3D cybertypes of the new species derived from X-ray micro-computed tomography.

X-Ray microtomography for ant taxonomy: An exploration and case study with two new Terataner (Hymenoptera, Formicidae, Myrmicinae) species from Madagascar.

We explore the potential of x-ray micro computed tomography (µCT) for the field of ant taxonomy by using it to enhance the descriptions of two remarkable new species of the ant genus Terataner: T. balrog sp. n. and T. nymeria sp. n.. We provide an illustrated worker-based species identification key for all species found on Madagascar, as well as detailed taxonomic descriptions, which include diagnoses, discussions, measurements, natural history data, high-quality montage images and distribution maps for both new species. In addition to conventional morphological examination, we have used virtual reconstructions based on volumetric µCT scanning data for the species descriptions. We also include 3D PDFs, still images of virtual reconstructions, and 3D rotation videos for both holotype workers and one paratype queen. The complete µCT datasets have been made available online (Dryad, https://datadryad.org) and represent the first cybertypes in ants (and insects). We discuss the potential of µCT scanning and critically assess the usefulness of cybertypes for ant taxonomy.

Taxonomy of the hyper-diverse ant genus Tetramorium Mayr in the Malagasy region (Hymenoptera, Formicidae, Myrmicinae) - first record of the T.setigerum species group and additions to the Malagasy species groups with an updated illustrated identification key.

In this study we provide an update to the taxonomy of the ant genus Tetramorium Mayr in Madagascar. We report the first record of the Tetramoriumsetigerum species group in Madagascar and describe the only Malagasy representative as Tetramoriumcavernicola sp. n., which is known only from a cave in Ankarana. In addition, we provide an overview of the 19 proposed Malagasy species groups, and discuss their zoogeography and relationships to other groups and larger lineages within the hyper-diverse genus Tetramorium. At present, we recognise a highly unique Malagasy Tetramorium fauna with 113 species endemic to the island of Madagascar out of a total of 125 translating into an endemism rate of 93%. We hypothesise that this fauna is based on one or a few colonisation events from the Afrotropical region, with subsequent adaptive radiation in Madagascar. Furthermore, we present an updated and illustrated identification key to the Tetramorium species groups in the Malagasy region.

Revision of the ant genus Proceratium Roger (Hymenoptera, Proceratiinae) in Fiji.

The Fiji archipelago harbours a surprisingly diverse and endemic ant fauna, despite its isolated and remote location in the South Pacific. The ant genus Proceratium is present on Fiji with three endemic species, of which Proceratiumoceanicum De Andrade, 2003 and Proceratiumrelictum Mann, 1921 were previously known. In this study we describe the third species: Proceratiumvinaka sp. n. All three species are members of the widespread and species-rich Proceratiumsilaceum clade. In order to integrate the new species into the current taxonomic system, we present an illustrated identification key to the worker caste of the three Fijian species. In addition, we provide a detailed description of Proceratiumvinaka, as well as species accounts for the other two species, which include diagnoses, taxonomic discussions, specimen photographs, and a distribution map.

Taxonomy of the ant genus Proceratium Roger (Hymenoptera, Formicidae) in the Afrotropical region with a revision of the P.arnoldi clade and description of four new species.

The taxonomy of the genus Proceratium Roger is updated for the Afrotropical region. We give an overview of the genus in the region, provide an illustrated identification key to the three clades (Proceratiumarnoldi, Proceratiumstictum and Proceratiumtoschii clades) and revise the Proceratiumarnoldi clade. Four new species from the Proceratiumarnoldi clade are described as new: Proceratiumsokoke sp. n. from Kenya, Proceratiumcarri sp. n. from Mozambique, and Proceratiumnilo sp. n. and Proceratiumsali sp. n. from Tanzania. In order to integrate the new species into the existing taxonomic system we present an illustrated identification key to distinguish the seven Afrotropical species of the Proceratiumarnoldi clade. In addition, we provide accounts for all members of the Proceratiumarnoldi clade including detailed descriptions, diagnoses, taxonomic discussions, distribution data and high quality montage images.

The hyper-diverse ant genus Tetramorium Mayr (Hymenoptera, Formicidae) in the Malagasy region taxonomic revision of the T. naganum, T. plesiarum, T. schaufussii, and T. severini species groups.

The taxonomy of the Tetramorium naganum, T. plesiarum, T. schaufussii, and T. severini species groups are revised for the Malagasy region. A total of 31 species are treated, of which 22 are newly described and nine redescribed. This increases the richness of the hyper-diverse genus Tetramorium in the Malagasy region to 106 species, which makes it the most species-rich genus in the region. Twenty-nine of the treated species are endemic to Madagascar, one is endemic to the Comoros, and one species is found predominantly in Madagascar but also on the island of Reunion. The T. naganum species group contains five species, which are mainly distributed in the rainforests and montane rainforests of eastern and northern Madagascar: T. alperti sp. n., T. dalek sp. n., T. enkidu sp. n., T. gilgamesh sp. n., and T. naganum Bolton, 1979. The T. plesiarum species group holds five species: T. bressleri sp. n., T. hobbit sp. n., T. gollum sp. n., T. mars sp. n., and T. plesiarum Bolton, 1979. All five are arid-adapted species occurring in the southwest and west of Madagascar. The second-most species-rich group in the region is the T. schaufussii species group with 20 species, most of which inhabit rainforests or montane rainforests of eastern and northern Madagascar. This group includes two species complexes each containing ten species: the T. cognatum complex with the species T. aspis sp. n., T. camelliae sp. n., T. cognatum Bolton, 1979, T. freya sp. n., T. gladius sp. n., T. karthala sp. n., T. myrmidon sp. n., T. proximum Bolton, 1979, T. rumo sp. n., and T. tenuinode sp. n.; and the T. schaufussii complex with the species T. merina sp. n., T. monticola sp. n., T. nassonowii Forel, 1892 stat. n., T. obiwan sp. n., T. pseudogladius sp. n., T. rala sp. n., T. schaufussii Forel, 1891, T. sikorae Forel, 1892 (= T. latior (Santschi, 1926)), T. scutum sp. n., T. xanthogaster Santschi, 1911. The last group treated in this study is the T. severini species group, which contains only the species T. severini (Emery, 1895). This very conspicuous species is widely distributed in the rainforests and montane rainforests of eastern and northern Madagascar. All four groups are fully revised with group diagnoses, illustrated species-level identification keys, and detailed descriptions for all species that include multifocused montage images and distribution maps.

The ant genus Tetramorium Mayr in the Afrotropical region (Hymenoptera, Formicidae, Myrmicinae): synonymisation of Decamorium Forel under Tetramorium, and taxonomic revision of the T. decem species group.

In this study we synonymise the genus Decamorium Forel under Tetramorium Mayr, revise the new T. decem species group by providing a diagnosis of the group, an illustrated identification key to species level, and worker-based species descriptions for all five species, which include diagnoses, discussions, images, and distribution maps. The following species are revised in this study: T. decem Forel, comb. r., T. raptor sp. n., T. uelense Santschi, comb. r., T. ultor Forel, comb. r., stat. r. & stat. n., and T. venator sp. n. In addition, we also designate lectotypes for T. decem, T. uelense, and T. ultor.

Improved phylogenetic analyses corroborate a plausible position of Martialis heureka in the ant tree of life.

Martialinae are pale, eyeless and probably hypogaeic predatory ants. Morphological character sets suggest a close relationship to the ant subfamily Leptanillinae. Recent analyses based on molecular sequence data suggest that Martialinae are the sister group to all extant ants. However, by comparing molecular studies and different reconstruction methods, the position of Martialinae remains ambiguous. While this sister group relationship was well supported by Bayesian partitioned analyses, Maximum Likelihood approaches could not unequivocally resolve the position of Martialinae. By re-analysing a previous published molecular data set, we show that the Maximum Likelihood approach is highly appropriate to resolve deep ant relationships, especially between Leptanillinae, Martialinae and the remaining ant subfamilies. Based on improved alignments, alignment masking, and tree reconstructions with a sufficient number of bootstrap replicates, our results strongly reject a placement of Martialinae at the first split within the ant tree of life. Instead, we suggest that Leptanillinae are a sister group to all other extant ant subfamilies, whereas Martialinae branch off as a second lineage. This assumption is backed by approximately unbiased (AU) tests, additional Bayesian analyses and split networks. Our results demonstrate clear effects of improved alignment approaches, alignment masking and data partitioning. We hope that our study illustrates the importance of thorough, comprehensible phylogenetic analyses using the example of ant relationships.