Linguamyrmex
| Linguamyrmex Temporal range:
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|---|---|
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| Linguamyrmex vladiHolotype worker | |
Scientific classification
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| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Arthropoda |
| Class: | Insecta |
| Order: | Hymenoptera |
| Family: | Formicidae |
| Subfamily: | †Haidomyrmecinae |
| Genus: | †Linguamyrmex Barden & Grimaldi, 2017 |
| Species | |
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Linguamyrmexis anextinctgenusofantin theformicidsubfamilyHaidomyrmecinae,and is one of only nine genera placed in the subfamilyHaidomyrmecinae.The genus contains three described species,Linguamyrmex brevicornis,Linguamyrmex rhinocerus,and the type speciesLinguamyrmex vladiall known fromLate Cretaceousfossils found inAsia.
History and classification[edit]
Linguamyrmexis known from a total of four adult fossils. Theholotypeis specimen number "AMNH BuPH-01" from the American Museum of Natural History; the other three specimens described are also in the same collection, but were not placed as members ofL. vladi.The described specimens are ofworker casteadults which have been preserved asinclusionsin transparent chunks ofBurmese amber.[1]Theamberspecimens were recovered from deposits inKachin State,in Myanmar. Burmese amber has beenradiometrically datedusingU-Pbisotopes, yielding an age of approximately 98.79 ± 0.62 million years old, close to theAlbian–Cenomanianboundary, in the earliest Cenomanian.[2][3][4][5]
The fossils were first studied by paleoentomologists Phillip Barden and David Grimaldi with their 2017type descriptionof the new genus and species being published in the journalSystematic Entomology.[1]The genus nameLinguamyrmexwas formed as a combination of theGreek"myrmex" which means ant, and theLatin"lingua", which means tongue, as a reference to the shape and appearance of the clypeal projection. Thespecific epithetvladiis a patronym honoring Vlad III, known asVlad the Impaler,who was the ruler ofWallachia.It was coined as a reference to both Vlad's preferred execution style and for his inspiration ofBram Stoker'sCount Dracula,who drank blood.[1]
The three remaining workers studied, BuPH-02, BuPH-03, and BuPH-04 were assigned toLinguamyrmexdue to several factors. Each of the specimens is incomplete, all missing portions of the antennae, making comparison of the scape length to the other segments impossible, and all specimens are missing the terminal segments of the gaster. Based on the worker size and on paddle composition Barden and Grimaldi suggest the three workers may belong to undescribed species.[1]
Linguamyrmexis one of several ant genera described from Burmese amber, the others beingBurmomyrma,Camelomecia,Ceratomyrmex,Gerontoformica,Haidomyrmex,Myanmyrma,andZigrasimecia.[2][4][5][1]Linguamyrmexis one of five genera in Haidomyrmecini, the other four beingCeratomyrmex,Haidomyrmex,HaidomyrmodesandHaidoterminus.The genus is distinguished from them by the well developed gasteral constriction on the abdomen, a feature only seen, to a lesser degree, inHaidomyrmodes mammuthus.AdditionallyLinguamyrmexhas an enlarged and paddle shapedclypeus,similar to the extremely modified clypeus ofCeratomyrmex,but which is smooth along the stalk instead of sporting setae, and with trigger hairs placed at the base of the setae pad on the paddle instead of at the base of the paddle stalk.[1]
Behavior and ecology[edit]
As with all haidomyrmecine members, the head structure ofLinguamyrmexis interpreted to facilitate trap-jaw behavior, as is seen in modern specialized genera of Formicinae, Myrmicinae and Ponerinae. In haidomyrmecines the clypeus is modified to span from near the oral opening up past the mandibles to near the vertex of the head, the only ant group with such a modification. Along with the clypeal structuring a pair of long setae are positioned in the path of the mandibles. In modern trap-jaw ants such setae are used as triggers that initiate the rapid closure of the mandibles, often to capture prey or sometimes in a defensive action. The upper areas of the clypeus are always coated in a brush of stout setae in the region where the mandibles came to rest when triggered to close. Based on the modification of the clypeus, it is probable thatLinguamyrmexwould have captured prey from the front, other strategies being made improbable due to the upward motion of the mandibles. In haidomyrmecines with highly modified cleypeal areas, such asLinguamyrmexandCeratomyrmexthe horn probably served as a pinning or trapping point for the mandibles with captured prey.[1]
This hypothesis for the purpose of the clypeus inLinguamyrmexis further supported by data obtained fromX-ray micro-computed tomography scansof specimen "BuPH-03". Scanning of the specimen shows density variation in the paddle, with the outer edges less dense than the central core area on the paddles underside. This indicates the paddle was strengthened with thickened cuticle or with metals sequestering in the cuticle, the latter being more likely from the distinct contrast shown in the x-ray.[1]The location of the highest density is near the center of the paddle at the point of impact for the mandibles when they closed, likely to help brace the paddle against misfires of the mandibles, or impact through soft bodied prey, such as beetle larvae. Metals such as calcium, iron, manganese, and zinc are used by insects in both mandibles and ovipositors to reduce wear and increase durability.[1]
Description[edit]
The head of theLinguamyrmexholotype measures 1.86 mm (0.07 in) from the front edge of the clypeus to the rear of the head at the occipital foramen, which is placed high on the back side, near the vertex. There are threeocelliplaced just to the front of the vertex, and the bulging ovoidcompound eyesare positioned high on the head capsule. The antennae are not fully preserved, with only three full segments, the scape, pedicel, and flagellomere I. The antennae insertion is just in front of and below the eyes, positioned in depressions on each side of the frontal triangle. The frontal triangle extends down from the vertex and merges with the base of the clypeal horn, which is reinforced with clear membrane-like cuticle. The clypeus is enlarged and modified into a paddle shaped horn that has a pad of setae on the underside. The stalk of the horn is smooth, with no setae, and the trigger hairs seen in haidomyrmecines sprout from near the base of the setae pad on the paddle. The pad is composed of long fine setae around the edges changing to shorter thicker setae in the center. Themandiblesscytheshaped in general outline, curving out and upwards from the head towards the clypeal horn. There are expansions near the base of each mandible which angle in towards each other, and which have upper surfaces that are concave and covered with setae pointing towards the mouth.[1]
Themesosomahas a smallpropleuronthat is hidden except where the mesosoma touches the head capsule, while thepronotumis broad and has a coating of fine setae. To the rear of the mesosoma, thepropodeumis gently rounded upper front face that curves to become a shear rear face. Both the propodeal spiracle andmetapleural glandare visible on the sides of the mesosoma, with the spiracle elongated into a slit shape, while metapleural gland is a horizontal opening placed rear of a well-developed bulla. Thepetiolehas a gradually sloping front face and rounded upper surface. The rear is broadly attached to gasteral segment I and the distinctly showing helcium is striated. An incomplete fusion line runs along the side of the petiole and gaster, with a thin membranous section present below, while a constriction between segments I and II that rings the full gaster. There is a forward projecting horn on the underside of sternite III that also has distinct striations. The cuticle of the gaster is translucent, which shows that theapodemesof gastral sternites IV and V are expanded and heavily sclerotized.[1]
References[edit]
- ^abcdefghijkBarden, P; Herhold, H. W.; Grimaldi, D. A. (2017)."A new genus of hell ants from the Cretaceous (Hymenoptera: Formicidae: Haidomyrmecini) with a novel head structure".Systematic Entomology.42(4): 837–846.Bibcode:2017SysEn..42..837B.doi:10.1111/syen.12253.
- ^abPerrichot, V.; Wang, B.; Engel, M. S. (2016)."Extreme Morphogenesis and Ecological Specialization among Cretaceous Basal Ants".Current Biology.26(11): 1468–1472.Bibcode:2016CBio...26.1468P.doi:10.1016/j.cub.2016.03.075.PMID27238278.
- ^Shi, G.; Grimaldi, D.A.; Harlow, G.E.; Wang, Ji.; Wang, Ju.; Yang, M.; Lei, W.; Li, Q.; Li, X. (2012). "Age constraint on Burmese amber based on U-Pb dating of zircons".Cretaceous Research.37:155–163.Bibcode:2012CrRes..37..155S.doi:10.1016/j.cretres.2012.03.014.
- ^abBarden, P.; Grimaldi, D. (2013)."A New Genus of Highly Specialized Ants in Cretaceous Burmese Amber (Hymenoptera: Formicidae)"(PDF).Zootaxa.3681(4): 405–412.doi:10.11646/zootaxa.3681.4.5.PMID25232618.
- ^abBarden, P.; Grimaldi, D.A. (2016)."Adaptive radiation in socially advanced stem-group ants from the Cretaceous".Current Biology.26(4): 515–521.Bibcode:2016CBio...26..515B.doi:10.1016/j.cub.2015.12.060.PMID26877084.
External links[edit]
Media related toLinguamyrmexat Wikimedia Commons
