A revision of male ants of the Malagasy Amblyoponinae (Hymenoptera: Formicidae) with resurrections of the genera Stigmatomma and Xymmer

A checklist of Nigerian ants (Hymenoptera, Formicidae): a review, new records and exotic species

Background

Ants are one of the most ubiquitous, widespread and abundant groups of animals on Earth. They are eusocial and are well noted for their important ecosystem services such as nutrient recycling, seed dispersal, engaging in mutualistic associations with other organisms, as well as serving as predators and scavengers. Although Africa has been recognised as a global hotspot for ant diversity, African ant genera are not as well-known when compared with other regions. The last checklist of Nigerian ants was compiled and published in the 1970s. To contribute to new knowledge on West African ant genera and Nigeria in particular, we conducted a review of the ant species of Nigeria using 132 scientific publications mostly compiled in the database www.antmaps.org, along with a survey of ant species of Lagos and Oyo States in Nigeria which was conducted between 2018 and 2020. The study aimed to ascertain the diversity of Nigerian ant genera, as well as to confirm the presence of previously recorded species and add new species to the current checklist of Nigerian ants, based on the 1970 survey.

New information

As many as 106 species were recorded from the survey in the current study, of which 28 are new to Nigeria and additional 28 are identified to the morphospecies level. In total, 317 species from 10 subfamilies and 64 genera are now recorded from Nigeria, including 11 invasive ants, of which six are new to Nigeria. The following eleven species that were included in the 1970 checklist were excluded from the current list, mostly due to previous misidentifications: Aenictusrotundatus Mayr, 1901; Anochetusjonesi Arnold, 1926; Camponotusbarbarossamicipsa Wheeler, 1992; Camponotusforaminosusdorsalis Santschi, 1926; Camponotusrufoglaucus (Jerdon, 1851); Cardiocondylazoserka Bolton, 1982; Messorbarbarus (Linnaeus, 1767); Odontomachushaematodus (Linnaeus, 1758); Technomyrmexalbipes (Smith, 1861); Tetramoriumdecem Forel, 1913 and Tetraponerapenzigi (Mayr, 1907).

Ants (Hymenoptera: Formicidae) from Miocene Ethiopian amber: filling gaps in the geological record of African terrestrial biota

The Early Miocene (16–23 Mya) amber of Ethiopia constitutes a new source of fossil ants for Africa, where they are otherwise poorly documented. Here we report a diversified assemblage of six subfamilies and at least 19 genera that are still predominantly alive in the Afrotropics today. In this first account, a particular reference is made to the subfamily Dolichoderinae, with the description of two new species: Technomyrmex svojtkai Perrichot & Engel sp. nov. and Ravavy goldmani Boudinot & Perrichot sp. nov. The first is illustrated and described based on synchrotron-radiation microcomputed tomography, and the second represents the first fossil record for the tribe Bothriomyrmecini and Ravavy, a Malagasy and Afrotropical genus that was hitherto monotypic. The ant composition in Ethiopian amber is congruent with the global pattern emerging across ants and showing a Neogene diversification almost exclusively within extant genera.

Snap-jaw morphology is specialized for high-speed power amplification in the Dracula ant, Mystrium camillae

What is the limit of animal speed and what mechanisms produce the fastest movements? More than natural history trivia, the answer provides key insight into the form-function relationship of musculoskeletal movement and can determine the outcome of predator-prey interactions. The fastest known animal movements belong to arthropods, including trap-jaw ants, mantis shrimp and froghoppers, that have incorporated latches and springs into their appendage systems to overcome the limits of muscle power. In contrast to these examples of power amplification, where separate structures act as latch and spring to accelerate an appendage, some animals use a 'snap-jaw' mechanism that incorporates the latch and spring on the accelerating appendage itself. We examined the kinematics and functional morphology of the Dracula ant, Mystrium camillae, who use a snap-jaw mechanism to quickly slide their mandibles across each other similar to a finger snap. Kinematic analysis of high-speed video revealed that snap-jaw ant mandibles complete their strike in as little as 23 µsec and reach peak velocities of 90 m s-1, making them the fastest known animal appendage. Finite-element analysis demonstrated that snap-jaw mandibles were less stiff than biting non-power-amplified mandibles, consistent with their use as a flexible spring. These results extend our understanding of animal speed and demonstrate how small changes in morphology can result in dramatic differences in performance.

A sibling species of Platythyrea clypeata Forel, 1911 in southeast Asia (Hymenoptera, Formicidae, Ponerinae)

A new species of the rarely collected ant genus Platythyrea Roger, 1863 closely related to Platythyreaclypeata Forel, 1911 is described and illustrated based on the worker caste under the name Platythyreajanyaisp. n. This species is distributed in southern Thailand and western Malaysia, while P.clypeata is distributed in Sri Lanka, Vietnam, Laos, and Thailand in the areas north of the Isthmus of Kra. Platythyreaclypeata is newly recorded from Thailand from dead wood on the forest floor. The type series of P.janyai was also collected from rotten wood on the forest floor.

Giant ants and their shape: revealing relationships in the genus Titanomyrma with geometric morphometrics

Shape is a natural phenomenon inherent to many different lifeforms. A modern technique to analyse shape is geometric morphometrics (GM), which offers a whole range of methods concerning the pure shape of an object. The results from these methods have provided new insights into biological problems and have become especially useful in the fields of entomology and palaeontology. Despite the conspicuous successes in other hymenopteran groups, GM analysis of wings and fossil wings of Formicidae has been neglected. Here we tested if landmarks defining the wing shape of fossil ants that belong to the genus Titanomyrma are reliable and if this technique is able to expose relationships among different groups of the largest Hymenoptera that ever lived. This study comprises 402 wings from 362 ants that were analysed and assigned with the GM methods linear discriminant function analysis, principal component analysis, canonical variate analysis, and regression. The giant ant genus Titanomyrma and the parataxon Formicium have different representatives that are all very similar but these modern methods were able to distinguish giant ant types even to the level of the sex. Thirty-five giant ant specimens from the Eckfeld Maar were significantly differentiable from a collection of Messel specimens that consisted of 187 Titanomyrma gigantea females and 42 T. gigantea males, and from 74 Titanomyrma simillima females and 21 T. simillima males. Out of the 324 Messel ants, 127 are newly assigned to a species and 223 giant ants are newly assigned to sex with GM analysis. All specimens from Messel fit to the two species. Moreover, shape affinities of these groups and the species Formicium brodiei, Formicium mirabile, and Formicium berryi, which are known only from wings, were investigated. T. gigantea stands out with a possible female relative in one of the Eckfeld specimens whereas the other groups show similar shape patterns that are possibly plesiomorphic. Formicidae are one of the most dominant taxa in the animal kingdom and new methods can aid in investigating their diversity in the present and in deep time. GM of the ant wing delivers significant results and this core of methods is able to enhance the toolset we have now to analyse the complex biology of the ants. It can prove as especially useful in the future when incorporated into better understanding aspects of evolutionary patterns and ant palaeontology.

A new species of Stigmatomma from Taiwan (Hymenoptera, Formicidae, Amblyoponinae)

Stigmatomma is the most speciose ant genus in the subfamily Amblyoponinae. In the present paper, the worker caste of a new species is described, S.luyiaesp. n., which was collected from a soil sample in a subtropical evergreen broad-leaved forest in Taiwan. An identification key to the females of Stigmatomma species with 11 antennomeres occurring in Asia is also provided.

Revision of the fungus-farming ant genus Sericomyrmex Mayr (Hymenoptera, Formicidae, Myrmicinae)

The genus Sericomyrmex Mayr (Formicidae: Myrmicinae: Attini) is a Neotropical group of fungus-farming ants known for its problematic taxonomy, caused by low morphological variability across the species, vague and old species descriptions, and an outdated and incomplete key published in 1916. Recent molecular studies revealed that Sericomyrmex is the product of a rapid recent radiation, with a divergence date of 4.3 million years ago. Here we present a comprehensive taxonomic revision of the genus Sericomyrmex based on morphology and a recently published molecular phylogeny. We discuss and illustrate morphological characters for Sericomyrmex workers, males, queens, and larvae. We report 18 standard morphological measurements and 5 indices for 529 workers, 50 queens, and 39 males, which we employ in morphometric analyses. The revised genus Sericomyrmex comprises eleven species, including three new species, here described as S. maravalhassp. n., S. radioheadisp. n., and S. saramamasp. n. We also redescribe S. amabilis Wheeler, S. bondari Borgmeier, S. lutzi Wheeler, S. mayri Forel, S. opacus Mayr, S. parvulus Forel, S. saussurei Emery, and S. scrobifer Forel. The number of recognized species (11) is lower than the previously recognized 19 species and 3 subspecies. The following species and subspecies are synonymized: under S. opacus [=S. aztecus Forel syn. n., S. zacapanus Wheeler syn. n., and S. diego Forel syn. n.]; under S. bondari [=S. beniensis Weber syn. n.]; under S. mayri [=S. luederwaldti Santschi syn. n., S. moreirai Santschi syn. n., S. harekulli Weber syn. n., S. harekulli arawakensis Weber syn. n., S. urichi Forel syn. n.]; under S. saussurei [=S. burchelli Forel syn. n., S. impexus Wheeler syn. n., S. urichi maracas Weber syn. n.]; and under S. parvulus [=S. myersi Weber syn. n.]. We provide a key to Sericomyrmex species for the worker caste and information on the geographic distributions of all species.

Revision of the Malagasy Camponotus edmondi species group (Hymenoptera, Formicidae, Formicinae): integrating qualitative morphology and multivariate morphometric analysis

The Malagasy Camponotusedmondi species group is revised based on both qualitative morphological traits and multivariate analysis of continuous morphometric data. To minimize the effect of the scaling properties of diverse traits due to worker caste polymorphism, and to achieve the desired near-linearity of data, morphometric analyses were done only on minor workers. The majority of traits exhibit broken scaling on head size, dividing Camponotus workers into two discrete subcastes, minors and majors. This broken scaling prevents the application of algorithms that uses linear combination of data to the entire dataset, hence only minor workers were analyzed statistically. The elimination of major workers resulted in linearity and the data meet required assumptions. However, morphometric ratios for the subsets of minor and major workers were used in species descriptions and redefinitions. Prior species hypotheses and the goodness of clusters were tested on raw data by confirmatory linear discriminant analysis. Due to the small sample size available for some species, a factor known to reduce statistical reliability, hypotheses generated by exploratory analyses were tested with extreme care and species delimitations were inferred via the combined evidence of both qualitative (morphology and biology) and quantitative data. Altogether, fifteen species are recognized, of which 11 are new to science: Camponotusalamainasp. n., Camponotusandroysp. n., Camponotusbevohitrasp. n., Camponotusgalokosp. n., Camponotusmatsilosp. n., Camponotusmifakasp. n., Camponotusorombesp. n., Camponotustafosp. n., Camponotustratrasp. n., Camponotusvaratrasp. n., and Camponotuszavosp. n. Four species are redescribed: Camponotusechinoploides Forel, Camponotusedmondi André, Camponotusethicus Forel, and Camponotusrobustus Roger. Camponotusedmondiernesti Forel, syn. n. is synonymized under Camponotusedmondi. This revision also includes an identification key to species for both minor and major castes, information on geographic distribution and biology, taxonomic discussions, and descriptions of intraspecific variation. Traditional taxonomy and multivariate morphometric analysis are independent sources of information which, in combination, allow more precise species delimitation. Moreover, quantitative characters included in identification keys improve accuracy of determination in difficult cases.

Taxonomic revision of the Malagasy Nesomyrmex madecassus species-group using a quantitative morphometric approach

Here we reveal the diversity of the next fragment of the Malagasy elements of the ant genus Nesomyrmex using a combination of advanced exploratory analyses on quantitative morphological data. The diversity of the Nesomyrmexmadecassus species-group was assessed via hypothesis-free nest centroid clustering combined with recursive partitioning to estimate the number of clusters and determine the most probable boundaries between them. This combination of methods provides a highly automated species delineation protocol based on continuous morphometric data, and thereby it obviates the need of subjective interpretation of morphological patterns. Delimitations of clusters recognized by these exploratory analyses were tested via confirmatory Linear Discriminant Analysis (LDA). Our results suggest the existence of four morphologically distinct species, Nesomyrmexflavussp. n., Nesomyrmexgibber, Nesomyrmexmadecassus and Nesomyrmexnitidussp. n.; all are described here and an identification key for their worker castes using morphometric data is given. Two members of the newly outlined madecasus species-group, Nesomyrmexflavussp. n. and Nesomyrmexnitidussp. n., represent true cryptic species. Geographic maps depicting species distributions and elevational information for the sites where populations of particular species were collected are also provided.

Taxonomic revision of Stigmatomma Roger (Hymenoptera: Formicidae) in the Malagasy region

In this study we present the first taxonomic revision of the ant genus Stigmatomma in the Malagasy biogeographic region, re-describe the previously known S. besucheti Baroni-Urbani, and describe seven new species to science (S. bolabola sp. n., S. irayhady sp. n., S. janovitsika sp. n., S. liebe sp. n., S. roahady sp. n., S. sakalava sp. n., and S. tsyhady sp. n.). The revision is based on the worker caste, but we provide brief descriptions of gynes and males for some species. Species descriptions, diagnosis, character discussion, identification key, and glossary are illustrated with 360 high-quality montage and SEM images. The distribution of Stigmatomma species in Madagascar are mapped and discussed within the context of the island's biomes and ecoregions. We also discuss how some morphometric variables describe the differences among the species in the bioregion. Open science is supported by providing access to R scripts, raw measurement data, and all specimen data used. All specimens used in this study were given unique identifies, and holotypes were imaged. Specimens and images are made accessible on AntWeb.org.

Diagnostic survey of Malagasy Nesomyrmex species-groups and revision of hafahafa group species via morphology based cluster delimitation protocol

Madagascar and its surrounding islands are among the world’s greatest biodiversity hotspots, harboring predominantly endemic and threatened communities meriting special attention from biodiversity scientists. Building on the considerable efforts in recent years to inventory the Malagasy ant fauna, the myrmicine genus Nesomyrmex is reviewed and (1) subdivided into four major groups based on salient morphological features corroborated by numeric morphology: angulatus-, hafahafa-, madecassus- and sikorai-groups, and (2) the hafahafa species-group endemic to Madagascar is revised. Diversity within hafahafa species-group was assessed via hypothesis-free nest-centroid-clustering combined with gap statistic to assess the number of clusters and to determine the most probable boundaries between them. This combination of methods provides a highly automatized, objective species delineation protocol based on continuous morphometric data. Delimitations of clusters recognized by these exploratory analyses were tested via confirmatory Linear Discriminant Analysis. These results suggest the existence of four morphologically distinct species, Nesomyrmexcapricornissp. n., Nesomyrmexhafahafasp. n., Nesomyrmexmedusussp. n. and Nesomyrmexspinosussp. n.; all are described and an identification key for their worker castes using morphometric data is provided. Two members of the newly outlined hafahafa species-group, Nesomyrmexhafahafasp. n., Nesomyrmexmedusussp. n., are distributed along the southeastern coast Madagascar and occupy rather large ranges, but two other species, Nesomyrmexcapricornissp. n. and Nesomyrmexspinosussp. n., are only known to occur in small and isolated forest, highlighting the importance of small forest patches for conserving arthropod diversity.

Taxonomy and distribution of the ant Cataglyphissetipes (Hymenoptera: Formicidae)

Taxonomy and distribution of the ant species Cataglyphissetipes (Forel, 1894) is herewith detailed. C.setipes is redescribed, based on workers, queens, and males. Photomontage images of all castes are provided. Information on the distribution and ecology of this species is also given. A key to the Indian species of Cataglyphis is presented.

Survey of the mosquitoes (Diptera: Culicidae) of Mayotte

A transversal survey of immature mosquitoes was conducted on Mayotte Island (France) in the Comoros Archipelago, western Indian Ocean, with the aim to inventory the Culicidae and to document inter-species relationships in different habitats. In total 420 habitats were sampled for larvae and/or pupae mosquitoes, resulting in more than 6,000 specimens. Forty species belonging to 15 genera were collected, with eight taxa integrated for the first time to the Mayotte mosquito list. The most frequently recorded species were Stegomyia aegypti, St. albopicta, Anopheles gambiae and Eretmapodites subsimplicipes, the first three species being known vectors of viruses and parasites transmitted to humans. Mean species richness in habitats ranged from 1.00 to 3.29, with notable differences between habitats. For example, water-filled axils of banana leaves, tree-holes and crab-holes had low species richness, while cut bamboo, water pools, abandoned tires and marsh and swamp water had notably higher species richness. Twenty-seven mosquito species belonging to 12 genera were routinely collected (in ≥20% of at least one type of larval habitat) suggesting that multiple species play a role in the biocenosis of these aquatic habitats. Multispecies association was observed in 52% of the habitats. The co-occurrence of up to six species belonging to five genera was recorded in a single habitat. The mosquitoes of Mayotte show notable biogeographical affinities to those of Madagascar, as compared to the African continent. These two potential source areas are nearly equidistant from Mayotte, which in turn indicates biased dispersal from east to west. Our findings suggest that with relatively short-term intensive sampling in different habitats, it is possible to approach exhaustive species inventories based on collection of larvae. Mayotte, with its modest elevation range and land surface, has a notable species richness of mosquitoes with 45 well-documented species belonging to 15 genera.

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.

A revision of the ant genus Mystrium in the Malagasy region with description of six new species and remarks on Amblyopone and Stigmatomma (Hymenoptera, Formicidae, Amblyoponinae)

The genus Mystrium is revised for the Malagasy region. Six species, Mystrium barrybresslerisp. n., Mystrium labyrinthsp. n., Mystrium equessp. n., Mystrium mirrorsp. n., Mystrium shadowsp. n., and Mystrium janovitzisp. n. are described as new. Two existing names, Mystrium fallax Forel and Mystrium stadelmanni Forel, are synonymized with Mystrium voeltzkowi Forel and Mystrium mysticum Roger, respectively. All recognized species, including species outside of the Malagasy region, are assigned to one of the three newly proposed species groups. The associations between existing names and males are reexamined, and males of eight of the ten Malagasy species are described or redescribed. The taxonomic history of Mystrium highlights the importance of using unique identifiers when designating type specimens and the use of deposited vouchers in phylogenetic and ecological studies. Keys to species for workers, queens, and males are provided. Furthermore, a neotype for Mystrium mysticum is designated, as well as lectotypes for Mystrium camillae Emery, Mystrium rogeri Forel, Mystrium fallax Forel, Mystrium oberthueri Forel, Mystrium stadelmanni Forel, and Mystrium voeltzkowi Forel. Stigmatomma gingivale (Brown) is reassigned to Amblyopone as comb. rev. and Amblyopone awa Xu & Chu, Amblyopone kangba Xu & Chu, Amblyopone meiliana Xu & Chu, and Amblyopone zomae Xu & Chu are transferred to the genus Stigmatomma as comb. n.

A synoptic review of the ant genera (Hymenoptera, Formicidae) of the Philippines

An overview of the history of myrmecology in the Philippine archipelago is presented. Keys are provided to the 11 ant subfamilies and the 92 ant genera known from the Philippines. Eleven ant genera (12%), including 3 undescribed genera, are recorded for the first time from the Philippines. The biology and ecology of the 92 genera, illustrated by full-face and profile photo-images, of Philippine ants are summarized in the form of brief generic accounts. A bibliography of significant taxonomic and behavioral papers on Philippine ants and a checklist of valid species and subspecies and their island distributions are provided.