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The ant tribe Dacetini: limits and constituent genera, with descriptions of new species (Hymenoptera, Formicidae)
... Most Strumigenys ants either placed in different genera. Strumigenys is currently the senior synonym of 28 named genera (Baroni Urbani and De Andrade 2007;Bolton 2020;Booher 2021). An easily seen difference between some of the species in former genera is in the shape of their mandibles. ...
... Other species have less elongated, sometimes almost triangular, mandibles that have teeth throughout the mandible, extending from base to apex. There are several synapomorphies found within this group but some authors found no single easily documented character to link all species currently placed in Strumigenys (Baroni Urbani and De Andrade 2007). However, Booher (2021) provided morphological and phylogenetic evidence that the current genus Strumigenys is monophyletic. ...
... The differences in mandible structure appears to affect the predatory behavior of Strumigenys ants. Jaws in Strumigenys have a basal mandibular process that is a locking mechanism on the lateral edge of the labrum (Gronenberg 1996), although this characteristic is shared with a few other ant genera closely related to Strumigenys (Baroni Urbani and De Andrade 2007). This mechanism allows for the mandibles to be opened until their bases engage the labrum and will then be held in place until the mechanism is released. ...
Ants in the genus Strumigenys have an assortment of structures that appear to hold environmental debris that acts as camouflage to facilitate their ability to feed on collembolans. Species use a species-specific assortment of structures with a general hair- or scale-like form. These structures can be categorized as brush hairs, which expand apically and often have peg- like extensions for greater surface area and holding ability; holding hairs, narrow cuticular structures that often have ridges and pointed extensions of the cuticle; or guard hairs, whose function may not be to hold debris but at times become covered with this material. Additionally, the sculpturing of the head often holds a coating of environmental debris. Each of the six species used in this study had a distinct pattern of these cuticular structures that are different from that of other species and can be considered to have a species-specific character. Six species of Strumigenys are studied using a scanning electron microscope.
... The genus is cosmopolitan, comprising 858 species [2]. Over the years, the great number of species and the morphological diversity among them have led researchers to engage in a long-lasting debate regarding whether they represent one, two, or various genera [1, [3][4][5][6][7]. Recently, molecular evidence has revealed the complex evolutionary history of the genus, with repeated evolution of similar forms in different biogeographic zones. ...
... It has also been found that lineages including short trap-jaw mandible ants in the Neotropics could have evolved multiple times from those with gripping mandible mechanisms [8]. Considering the repeated evolution of similar forms within the large clade containing all species, the hypothesis that Strumigenys exists as a single, hyperdiverse genus [6] is more likely; otherwise, the clade would need to be split into several genera, perhaps more than it had been in the past, prior to the 1990s (Strumigenys itself would be composed of the Neotropical long trap-jaw species only). ...
... More than two decades after the global revision, various isolated studies conducted worldwide have added species to the genus. In the Neotropical region, 24 new species have been described since 2000, for a current total number of 210 species [6,[10][11][12][13][14][15][16]. In this contribution, one additional species, Strumigenys flavianae sp. ...
Strumigenys is one of the largest genera of ants, and one of the few which has received relatively recent global taxonomic treatment at the species level. Despite this, many new species continue to be found in most biogeographic regions. Strumigenys flavianae sp. nov. is described based on material collected in Viçosa, in the state of Minas Gerais, among secondary growth remnants of the Brazilian Atlantic Forest. Three workers of this new taxon are known, and the lack of additional specimens in the main ant collections harboring Atlantic Forest ants indicates its rarity. Strumigenys flavianae can be differentiated from all Neotropical Strumigenys for its overall slenderness, flagellate and wire-like pilosity, extremely long head, large and medially notched subpetiolar spongiform tissue and a mostly reticulate pleura. The new species is distinct from all other species found in the Atlantic Forest. It has similarities to some Amazonian species in the hyphata-group (S. cincinnata and S. hyphata) and the probatrix-group (S. doryceps), while still having significant differences relative to both. Therefore, a new species group was created to account for the new species.
... Strumigenys Smith, 1860 is a hyperdiverse ant genus that currently comprises 879 extant species globally [1]. The implementation of new methodologies for studying soil and leaflitter fauna [2,3] has progressively increased the known diversity of Strumigenys, and several species are described worldwide each year [4][5][6][7][8][9][10]. Recent molecular evidence supports the hypothesis that the genus is monophyletic with a complex evolutionary history, which explains its division into several different genera by some authors in the past [11]. ...
... Molecular evidence recovered the group as paraphyletic, with its species divided into two distinct clades: one composed of species related to Strumigenys schulzi and the other of Strumigenys microthrix (Kempf, 1975) [11]. Currently, the schulzi group comprises 20 species, and since the revision by Bolton [4], three species have been described for the group: Strumigenys aequinoctialis DeAndrade, 2007 [5], Strumigenys subnuda MacGown & Hill, 2010 [13] and Strumigenys madrigalae Latkke and Aguirre, 2015 [7]. ...
The genus Strumigenys is the third most diverse among ants, having been reviewed globally. Despite this comprehensive review, new species are frequently discovered in most biogeographic regions. Here, we describe two new species, Strumigenys itannae sp. nov. and Strumigenys xoko sp. nov., based on material collected in the Amazon and the Brazilian Atlantic Forest. Additionally, new records for S. castanea, S. metrix, and S. orchibia are provided, expanding the known distribution of these species. We discuss morphological variation in S. schulzi and provide biological notes that indicate some species within the schulzi group are arboreal inhabitants. We provided an identification key for the newly described species as an amendment to the identification key for the Neotropical Strumigenys.
... , the catching mechanism of Acanthognathus (Gronenberg et al., 1998), a new revision that included the fossil species and an updated diagnosis for the genus (Bolton, 2000), a morphology-based phylogeny that included the Daceton genus-group and other Attini genera (Baroni Urbani & De Andrade, 2007), the description of Acanthognathus laevigatus by Galvis and Fernandez, 2009, which included an updated key for the genus, the first report of ergatoids in A. rudis, Acanthognathus brevicornis Smith, 1944, and Acanthognathus ocellatus Mayr, 1887 (Silva & Brandão, 2014), and the molecular studies that revealed the phylogenetic position of the Daceton genus-group within the Attini, as well as its internal organization (Ward, 2015;Branstetter et al., 2017). Despite these contributions, there is currently no data available on the cytogenetics of the genus. ...
The trap-jaw ant Acanthognathus Mayr, 1887 (Fomicidae: Myrmicinae) has been subject of various studies since 1969, but its cytogenetics remains unexplored. This study provides the first karyotype description of a representative of this genus, A. rudis, including chromosomal number, morphology, and the distribution of repetitive sequences. A colony collected in Southeastern Brazil exhibited a diploid number of 2n = 14 (12 metacentrics + 2 submetacentrics), the lowest number among the Daceton genus-group and the first Neotropical representative of this group to be karyologically studied. The rDNA clusters were located in the pericentromeric region of a single chromosome pair, (GA)n blocks cover the entire chromosome arms except for heterochromatic regions, and (TTAGG)n hybridized with the telomeres of all chromosomes, without interstitial telomeric sites. The repetitive sequence patterns align with those observed in other Neotropical Formicidae. Additionally, we documented new behavioral aspects of mandible use in A. rudis workers and provided the first images of its immature stages. These findings emphasize the need for further research on Acanthognathus and the other Daceton genus-group.
... This genus is the third largest ant genus including more than 800 species with and without trap-jaws. These ants are also morphologically highly diverse, which is reflected in a complex taxonomical history with several different genera eventually being synonymized under Strumigenys (Baroni Urbani and Andrade, 2007). Further, Strumigenys used to be placed in the tribe Dacetini that included all myrmicine trap-jaw ants. ...
The metapleural gland is a unique feature of the ant phenotype, but diversity in its anatomy and function across the ants is not well documented or understood. We studied the morphology of the metapleural gland in 20 mainly Oriental Strumigenys species using histology, scanning and transmission electron microscopy, and micro-CT. The gland is formed by a cluster of class-3 cells, their secretion is transported through a bundle of ducts into the sclerotized atrium and is guided along a series of parallel cuticular ridges towards the atrial opening. Among the examined species, queens have more gland cells than conspecific workers, while the examined males do not have the gland. The social parasite S. mutica has the most developed metapleural gland. In addition, we describe a novel class-1 atrial cone gland which is associated with the metapleural gland. The epithelium of this cone gland forms an invagination into the ventral atrium of the metapleural gland. The cuticular cone may be lacking in some Afrotropical and Neotropical species, although these may still contain the epithelial gland. The functional and evolutionary drivers of morphological variation in the exocrine system across species form interesting questions for future work.
... As part of a larger study examining a survey of the exocrine system in the ant genus Strumigenys, the infrabuccal pocket of these ants also raised our interest. With more than 800 described species, these small predatory ants that mainly feed on collembola, long formed the most speciose genus of the myrmicine tribe Dacetini (Bolton, 1999;Baroni Urbani and de Andrade, 2007). Recently this group was synonymized within the enlarged tribe Attini based on molecular evidence (Ward et al., 2015). ...
Proceratium melinum (Roger, 1860) y Strumigenys argiola (Emery, 1869) son unas hormigas de hábitos endo-geos y con pocas citas en toda su área de distribución sureuropea. Se recopilan las escasas citas existentes para ambas especies en el ámbito ibérico y se añaden varias a partir del hallazgo de sexuados durante sus vuelos nupciales. Se destaca el muestreo de masas de agua de poca entidad para la detección de especies endogeas poco registradas en la península. ////// Proceratium melinum (Roger, 1860) and Strumigenys argiola (Emery, 1869) are endogeous ants with few records through its southern European distribution area. The scarce existing records for both species in the Iberian area are compiled and several are added based on the discovery of sexual individuals during their nuptial flights. The sampling of small water bodies is highlighted for the detection of endogeous species that are rarely recorded in the Iberian Peninsula.
Eurhopalothrix floridana, a slow-moving, cryptic leaf-litter ant, is the only species in the Basiceros genus-group (formerly Tribe Basicerotini) found in the continental US. Before 2007, this species was reported solely from Florida. Researchers, however, questioned whether this species was native to Florida or if it was an exotic of undetermined geographic origin. Recent records of E. floridana from natural areas in Cuba (two sites), Dominican Republic (nine sites), and Isla de Mona, Puerto Rico (one site) suggest that E. floridana is probably native to the Greater Antilles. Here, we report new records of E. floridana from Florida and Georgia and consider evidence concerning whether this species is native or exotic to Florida. We compiled 121 earlier Florida site records of E. floridana, primarily in nature preserves, ranging from Key West (24.6°N) to Three Rivers State Park and Fort Clinch State Park (both 30.7°N). In 2012, we collected E. floridana at one site in Georgia: Crooked River State Park (30.8°N), the first record of this species in the state. In 2018–2022, we collected ants through leaf-litter extraction at 461 disturbed sites in Florida and southernmost Georgia (24.6°N–31.0°N), mostly under slash pine and oak trees growing by roadsides and parking lots. We found E. floridana in 69 of 229 leaf-litter extractions north of 28.5°N (including one record from Georgia: Saint Marys, 30.7°N), but in none of the 232 leaf-litter extractions south of 28.5°N. Co-occurrence analyses suggest that non-native ant species may be excluding E. floridana from disturbed sites in South Florida. The recent appearance of widespread E. floridana populations in north-central Florida is currently the strongest evidence that this species is not native to Florida. Genetic analyses are needed to evaluate more conclusively the status of E. floridana in Florida, Georgia, and the Greater Antilles.
The species of the ant genus Strumigenys Smith, 1860 from Southeast Asia are reviewed based on recent sampling efforts as well as unreported historical material from southern mainland China, Japan, Taiwan, Thailand and Vietnam. We report 42 new species records for these regions. A total of 20 species new to science are described: S. anhdaoae sp. nov., S. claviseta sp. nov., S. crinigera sp. nov., S. decumbens sp. nov., S. delicata sp. nov., S. densissima sp. nov., S. doydeei sp. nov., S. fellowesi sp. nov., S. intermedia sp. nov., S. jaitrongi sp. nov., S. liuweii sp. nov., S. longidens sp. nov., S. mediocris sp. nov., S. rongi sp. nov., S. scutica sp. nov., S. strummeri sp. nov., S. xenopilus sp. nov., S. yamanei sp. nov., S. zanderi sp. nov. and S. zhenghuii sp. nov. The descriptions of the existing species S. elegantula (Terayama & Kubota, 1989) and S. nathistorisoc Tang et al., 2019 are revised. Strumigenys formosensis Forel, 1912 syn. nov. is synonymized with S. feae Emery 1895 in the light of recently collected specimens. Three species complexes are created within the S. leptothrix-group: elegantulacomplex, leptothrix-complex and zanderi-complex, based on differences in dentition. A new species group, S. nathistorisoc-group, is introduced. The key to Strumigenys of East Asia (as Pyramica) by Bolton is partially revised to accommodate species from these species groups that were described since the publication of the key. Finally, the implication of our results to the region and the current limitation of species groups and complexes of the genus is discussed.
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