''Novomessor ensifer'' is a species of ant endemic to Mexico. A member of the genus ''

Novomessor ''Novomessor'' is a genus of ants that was described by Italian entomologist Carlo Emery in 1915. Until recently, the genus was thought to be a synonym of ''Aphaenogaster'', but a 2015 phylogenetic study concluded that the two genera were distin ...

'' in the subfamily

Myrmicinae Myrmicinae is a subfamily of ants, with about 140 extant genera; their distribution is cosmopolitan. The pupae lack cocoons. Some species retain a functional sting. The petioles of Myrmicinae consist of two nodes. The nests are permanent and ...

, it was first described by Swiss entomologist Auguste Forel in 1899. ''N. ensifer'' was originally a part of the genus ''

Aphaenogaster ''Aphaenogaster'' is a genus of myrmicine ants. About 200 species have been described, including 18 fossil species. They occur worldwide except in South America south of Colombia, sub-Saharan Africa, and Antarctica. They are often confused w ...

'' until a recent phylogenetic study concluded that ''Novomessor'' was genetically distinct and should be separated. The ant is a medium-sized species, measuring . The ant is ferruginous-colored in some certain parts of the body, and small workers (nanitics) in incipient colonies are noticeably different in color and body structure. ''N. ensifer'' is active throughout the day, where they forage on the ground and sometimes on low herbs. Colonies are found under stones and other objects in tropical dry forests and pine-oak forests. These ants are solitary foragers and predominantly feed on insects such as wasps and moths. The only known predator of ''N. ensifer'' is the

giant horned lizard The giant horned lizard (''Phrynosoma asio'') is a species of phrynosomatid lizard which is endemic to the Pacific coast of southern Mexico Mexico (Spanish: México), officially the United Mexican States, is a country in the southern port ...

(''Phrynosoma asio''). While nothing is known about its reproduction, nuptial flight may take place during spring or summer, where queens establish their nests under stones and other objects.

Taxonomy

''Novomessor ensifer'' was originally described as ''Aphaenogaster ensifera'' in 1899 by Swiss entomologist Auguste Forel, who provided the first description of ''N. ensifer'' in his third volume of Biologia Centrali-Americana. Among the genus ''

'', Italian entomologist Carlo Emery placed ''N. ensifer'' in the subgenus ''Deromyrma'' in 1915, although this is now a synonym. In 1934, the taxon ''Novomessor manni'' was described as a new species of ''Novomessor'' based on workers collected by

William M. Mann William Montana Mann (1886–1960) was an American entomologist and the fifth director of the National Zoological Park (United States), National Zoo in Washington, D.C. from 1925 until 1956. In 1921, he traveled on the Mulford Expedition to the ...

at Colima, Mexico. However, a study showed that ''N. manni'' was a synonym of ''N. ensifer''. Brown comments that ''N. manni'' was described as a new species because of the supposed distinct features between two type specimens of ''N. ensifer'', but Brown noticed no morphological differences. The exact type locality for ''N. manni'' is unknown, but entomologist Paul Kannowski speculates that the ant is restricted to arid scrub forests around the

Pacific Slope The Pacific Slope describes geographic regions in North American, Central American, and South American countries that are west of the continental divide and slope down to the Pacific Ocean. In North America, the Rocky Mountains mark the eastern bo ...

in Mexico. This speculation is consistent with the preferred habitat of ''N. ensifer''. ''Novomessor'' was synonymized in 1974, although evidence to retain it as a valid genus emerged when scientists discovered an exocrine gastral glandular system in two ''Novomessor'' species and none in ''Aphaenogaster''. However, ''N. ensifer'' does not have this glandular system. English

myrmecologist Myrmecology (; from Greek: wikt:μύρμηξ, μύρμηξ, ''myrmex'', "ant" and λόγος, ''logos'', "study") is a branch of entomology focusing on the science, scientific study of ants. Some early myrmecologists considered ant society as th ...

Barry Bolton Barry Bolton is an English myrmecologist, an expert on the classification, systematics, and taxonomy of ants, who long worked at the Natural History Museum, London. He is known especially for monographs on African and Asian ants, and for encyclo ...

argues that basing the genus on such feature cannot justify the separation of ''Novomessor'' and ''Aphaenogaster''. In 2015, a phylogenetic study concluded that ''Novomessor'' was genetically distinct from ''Aphaenogaster'', and the genus was revived from synonymy to include ''N. ensifer'', '' N. albisetosus'' and '' N. cockerelli'' as members of it.

Description

Novomessor ensifera casent0217816 h 1 high

''N. ensifer'' is a medium-sized species, measuring . Excluding the mandibles, the head is long and wide. The

scapes Parsons School of Design, known colloquially as Parsons, is a private art and design college located in the Greenwich Village neighborhood of New York City. Founded in 1896 after a group of progressive artists broke away from established Manhatta ...

of the antennae surpass the occipital margin, and the second segment of the funiculus is longer than the first. The third and fourth segments are the same length as each other, although they are longer than the second. Between the fifth and second last segments, they are much shorter except for the last one. The head is twice as long than broad, and it is widest behind the eyes. The larvae measure in length and appear similar to that of ''N. albisetosus''. The larvae can be distinguished by the abundance of hair with long stouts found on the body. The apical teeth of the mandibles are long and straight, whereas the medial teeth are much smaller. The posterior to the eyes are convex, where it converges towards the occiput (the back of the head) and forms a collar seen in several ''Aphaenogaster'' species. The ants have large, triangular mandibles with three apical teeth and a flat clypeus. The eyes are large with 400 facets, but workers from small incipient colonies only have 200 facets. Workers from incipient also differ from workers living in mature colonies, notably in size, body shape and coloration. The average length is ; the head is long and wide. The epinotal spines (spines found on the first abdominal segment that protect the

pedicel Pedicle or pedicel may refer to: Human anatomy *Pedicle of vertebral arch, the segment between the transverse process and the vertebral body, and is often used as a radiographic marker and entry point in vertebroplasty and kyphoplasty procedures ...

) are much shorter. Hair is also less noticeable on the workers. The ant has pubescence (soft short hair) abundant throughout some certain parts of the body, including the funiculi and tarsi. It is more sparse on the coxae, genae (an area on both sides of the head below the eyes), gaster and gula (the reduced sternite of the first segment of the thorax). Hairs on the scapes point downwards. Erect and suberect hair are seen all over the body in sparse numbers, although this varies. These hairs are not as abundant in comparison to other ''Novomessor'' species. The head and thorax are both ferruginous-colored, and the epinotal spines, legs and node are yellowish red. The antennal scapes are reddish brown and the abdomen is piceous brown. The hair exhibits a gold-like color. The suture is absent from the thorax, and the mesonotum is wider than the epinotum. The front portion of the mesonotum is narrow whereas the back is rectangular. The node is evenly round and oval shaped, the postpetiole is narrow at the front and the dorsum is feebly convex. The gaster is large and oval shaped.

Distribution and habitat

''N. ensifer'' is endemic to Mexico and can be found in tropical dry forests at altitudes of between above sea level. In some cases, colonies have been found below the Pacific Slope. The ant is found throughout several Mexican states within the east, including Guerrero and

Michoacán Michoacán, formally Michoacán de Ocampo (; Purépecha: ), officially the Free and Sovereign State of Michoacán de Ocampo ( es, Estado Libre y Soberano de Michoacán de Ocampo), is one of the 32 states which comprise the Federal Entities of ...

from the south, and Colima and Jalisco from the north. Nests are commonly found in basins and mountains along the Pacific Slope in pine-oak forests. Scrub-thorn forests are also abundant, consisting of trees and shrubs that are tall, but other areas may contain low herbs and grasses. Plants and trees such as thorn trees (''Acacia''), poinciana plants (''Caesalpinia pulcherrima)'' and '' Casearia corymbosa'' have been identified in these habitats. Other identified plants and trees include

Indian mallow ''Abutilon'' is a large genus of flowering plants in the mallow family, Malvaceae. It is distributed throughout the tropics and subtropicsspurred anodas ''(Anoda cristata)'', '' Cathestecum erectum'', dayflowers ''(Commelina)'', cigar plants ''(Cuphea)'',

hairy crabgrass ''Digitaria sanguinalis'' is a species of grass known by several common names, including hairy crabgrass, hairy finger-grass, large crabgrass, crab finger grass, purple crabgrass. It is one of the better-known species of the genus ''Digitaria'', ...

''(Digitaria sanguinalis)'', crane grass ''(Ixophorus unisetus)'', '' Mimosa'', Mexican panicgrass ''(Panicum hirticaule)'', '' Senna uniflora'' and '' Setaria liebmannii''. These habitats usually have a wet season in summer and autumn and a dry season in spring. ''N. ensifer'' is a

xerophilous A xerophile () is an extremophilic organism that can grow and reproduce in conditions with a low availability of water, also known as water activity. Water activity (aw) is measured as the humidity above a substance relative to the humidity above p ...

species that can thrive in dry climates. In Colima, colonies are frequent among the basins, but rarely are they found in the mountainous regions. ''N. ensifer'' ants prefer to nest in the sand and under large stones, as certain areas in Manzanillo had no stones buried in the soil and no colonies were found alongside hills with plain soil. Most colonies are found under stones with no noticeable craters surrounding the nest entrance, although one colony was found under an ''Acacia'' plant. These nest holes are usually in diameter. A single path connects the entrance to the main nest site, followed by a passage that descends straight into the dirt several inches deep. This passage widens under a stone which forms a gallery for the larvae and pupae. Wherever stones are formed, passageways may descend further into the ground and form more chambers. Although it is unknown how deep these passages go, excavated nests are as deep as .

Behavior and ecology

Unlike other ''Novomessor'' species, workers forage early in the morning and late afternoon, whereas ''N. cockerelli'' and ''N. albisetosus'' forage during the afternoon and evening. However, it is unknown whether or not these ants are active during the night. Foragers first emerge from their nests at 9 A.M. and return by 5 P.M. They are rarely seen during the middle of the day when temperatures reach 95–100 °F (35–38 °C), although the ground temperature is considerably higher. Workers are commonly seen foraging between 9 and 11 A.M. and 3 to 5 P.M. Most workers forage on the ground, but sometimes they can be seen walking on low herbage without feeding on the plants or collecting any seeds. Excavated nests showed no evidence that these ants collect seeds, and no workers were seen collecting them or carrying them back to the nest. ''N. ensifer'' ants are solitary foragers that work 25 ft (7 m) away from their home nest. ''N. ensifer'' predominantly feeds on insects they prey on, consuming dead insects such as

ichneumon wasps The superfamily Ichneumonoidea contains one extinct and three extant families, including the two largest families within Hymenoptera: Ichneumonidae and Braconidae. The group is thought to contain as many as 100,000 species, many of which have not ...

, bembicine wasps and small moths. When a worker discovers a dead insect, it will start to pull and carry it back to the nest immediately, and other nestmates will join once they detect it. Workers do not cooperate with each other and pull the insect from all directions, accidentally tearing it apart. However, the workers will eventually have a piece of the insect left and return it to the nest. The only known predator of ''N. ensifer'' is the

(''Phrynosoma asio'').

Mites Mites are small arachnids (eight-legged arthropods). Mites span two large orders of arachnids, the Acariformes and the Parasitiformes, which were historically grouped together in the subclass Acari, but genetic analysis does not show clear evid ...

and Springtail arthropods are known to dwell inside nests, but their function or purpose within a colony is unknown. Nothing is known about its reproduction or nuptial flight. Collectors note that no alates or pupae resembling alate forms were found in excavated colonies between August and February, and the larvae collected were not large enough to be reproductive ants. However, it is possible that nuptial flight takes place in spring or summer, and like ''N. albisetosus'' and ''N.cockerelli'', alates most likely start to occur by June. After nuptial flight, queens search for a suitable colony by building a chamber under objects such as stones and exposed roots of woody plants. This theory stated by entomologist Paul Kannowski is supported by the fact that these ants depend on stones buried in the soil for nest construction. The larvae and pupae are unsorted in the upper chambers of the nest that are joined together by hooked hairs on the side of the larvae. This arrangement most likely helps workers move the brood efficiently and keep them together in a group. Incipient colonies may only have 30 workers and brood in all life stages. Unlike the larvae and pupae, the eggs and queen are not found in the uppermost galleries, but rather they are found in the deepest chambers of the nest. In large nests, small workers resembling the first generation of brood are either rare or absent.

References

External links

* {{Taxonbar, from=Q13383351 Myrmicinae Insects described in 1899 Hymenoptera of North America Endemic insects of Mexico