Haidomyrmex
| Haidomyrmex Temporal range: EarliestCenomanian
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| Haidomyrmex zigrasiholotype | |
Scientific classification
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| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Arthropoda |
| Class: | Insecta |
| Order: | Hymenoptera |
| Family: | Formicidae |
| Subfamily: | †Haidomyrmecinae |
| Genus: | †Haidomyrmex Dlussky, 1996 |
| Species | |
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Haidomyrmexis anextinctgenusofantsin theformicidsubfamilyHaidomyrmecinae,and is one of nine genera placed in the subfamilyHaidomyrmecinae.The genus contains three described speciesHaidomyrmex cerberus,Haidomyrmex scimitarus,andHaidomyrmex zigrasi.All three are known from singleLate Cretaceousfossils which have been found inAsia.[1][2]H. cerberusis the type species andHaidomyrmexthe type genus for the subfamily Haidomyrmecinae.[1]
History and classification[edit]
Haidomyrmex,is known from three solitary adult fossil specimens which are composed of mostly complete adult females which have been preserved as aninclusionsin transparent chunk ofBurmese amber.Theamberspecimens entombingH. scimitarus,andH. zigrasiwere recovered from deposits inKachin State,100 kilometres (62 mi) west of Myitkyna town in Myanmar.[1]In contrast, type specimen ofH. cerberuswas collected in the early 1900s from an unspecified location in Myanmar. Burmese amber has beenradiometrically datedusingU-Pbisotopes, yielding an age of approximately 99 million years old, close to the boundary between theAptianandCenomanian.[1]The amber is suggested to have formed in a tropical environment around 5° north latitude and the resin to have been produced by either anAraucariaceaeorCupressaceaespecies tree.[3]The mandibles of Haidomyrmecini genera are unique among ants in having a movement along the vertical plane. All other species with a trap-jaw type mandible structure show movement along the horizontal plane. Barden and Grimaldi suggest that the mandibles may have been capable of opening up to between 140° and 180°, if 0° is a closed position with the mandible tips near the clypeus. The resulting gape that results from the open position is nearly twice the head capsule diameter. The long legs and antennae are both features seen inarborealant species,[1]and it has been suggested that the species may have nested in preexisting cavities in trees.[2]
TheholotypeofH. cerberus,specimen number "BMNH 20182" was deposited in theNatural History MuseumBurmese amber collection in London. Specimen number AMNH Bu-FB80 is the holotype forH. scimitarusand was part of an amber collection purchased from Federico Berlöcher by theAmerican Museum of Natural History.Unlike the other two species, at the time of description, the holotype forH. zigrasi,JZC-BuXX, was residing in the private collection of James Zigras and only loaned to the paleoentomologists for study.[1]
Despite its collection in the early 1900s fossils of the genus were not described until the Russian paleoentomologist Gennady M. Dlussky studiedH. cerberusnearly 80 years later. Dlussky published the 1996type descriptionof the new genus and species in thePaleontological Journal.The genus nameHaidomyrmexwas coined as a combination of theGreekwordHaidosmeaning "Hadesthe realm of the dead "andMyrmica,a genus of ants. Thespecific epithetcerberusrefers to the guardian of the underworldCerberus.[2]The second and third species in the genus were described in a single paper by Phillip Barden andDavid Grimaldi,both of theAmerican Museum of Natural History,published in the journalAmerican Museum Novitatesin 2012. The specific epithetscimitarusis a reference to the similar shape of the species mandibles and ascimitarwhile the epithetzigrasiis a patronym honoring James Zigras for his loan of specimens to study.[1]Haidomyrmexis one of five genera in Haidomyrmecini, the other four beingCeratomyrmex,Linguamyrmex,HaidomyrmodesandHaidoterminus.[3][4]
Descriptions[edit]
Overall the species ofHaidomyrmexare gracile ants which range from 3.0 to 8.0 millimetres (0.12 to 0.31 in) in length and have a generally smooth exoskeleton. All species show a lack ofocellibut have distinct bulging compound eyes. The antennae, where fully known, are long with eleven total segments[3]while theclypeusis generally developed into asetaecovered pad and sporting two long trigger hairs. The highly modified mandibles are generallyscytheto L-shaped and have only two teeth, displaying a hinge movement placing the tips of the mandibles on the clypeus surface. The structure of the mandibles and clypeus result in an elongated head. The legs are very long and the pretarsal claw has a single tooth while the metasoma show telescoping segments and a fully retractable sting.[1]
H. cerberusis known from a partial wingless female worker[1]estimated to have been 5 millimetres (0.20 in) long by Dlussky.[2]The L-shaped mandibles are positioned at an oblique angle to each other with a wide separation of the mandible bases and lack a margin for mastication of food items. The eyes are smaller than those seen onH. scimitarusand the mesonotum is short and more robust. In profileH.cerberushas amesonotumshowing distinctmetapleural glandsand apropodeumwhich is rounded. The tibia of the middle and hind legs sport two distinct spurs, a simple spur and a pectinate. Thegasteris only partially preserved, and absent from the second gastral segment back. Also missing from the specimen is the left trigger setae, left antenna and the right antenna after the seventh segment. The legs are present but detached from the body.[1][2]
The singleH. scimitarusspecimen is a preserveddealatequeen with a total body length of 8.0 millimetres (0.31 in), makingH. scimitarusthe largest of the three species. The mandibles are a distinct scythe shape, with a more distinct curve, rather the defined angle found inH. cerberus.The mandibles are positioned parallel to each other with the bases closely positioned to each other. The protruding clypeus is large and has a roughly pentagonal shape and two pairs of long fine trigger hairs on the ventral side. The gaster is 2.4 millimetres (0.094 in) long with telescoping tergites and a fully retractable sting 0.75 millimetres (0.030 in) in length.[1]
The smallest species of the three isH. zigrasi,with a length of just 3.5 millimetres (0.14 in), under half the length of either other species. The antennae have and exposed base and are an overall length of 1.93 millimetres (0.076 in). Unlike either of the other species, the compound eyes ofH. zigrasiare positioned in the front half of the head capsule while the eyes in bothH. cerberusandH. scimitarusare positioned near the middle of the head capsule. The smoothly curved mandibles curve up immediately from the base and sport an asymmetrical tooth near the base which projects downward. The left mandible's tooth is distinctly larger than that on the right mandible. The pairs of trigger hairs bracketing the mandible tips are 0.12 millimetres (0.0047 in) long, shorter than in the other species.[1]
References[edit]
- ^abcdefghijklBarden, P.; Grimaldi, D. (2012)."Rediscovery of the bizarre Cretaceous antHaidomyrmexDlussky (Hymenoptera: Formicidae), with two new species "(PDF).American Museum Novitates(3755): 1–16.doi:10.1206/3755.2.S2CID83598305.
- ^abcdeDlussky, G. M. (1996)."Ants (Hymenoptera: Formicidae) from Burmese amber".Paleontological Journal.30(4): 449–454.
- ^abcMcKellar, R. C.; Glasier, J. R. N.; Engel, M. S. (2013)."A new trap-jawed ant (Hymenoptera: Formicidae: Haidomyrmecini) from Canadian Late Cretaceous amber"(PDF).Canadian Entomologist.145(4): 454–465.doi:10.4039/tce.2013.23.hdl:1808/14425.S2CID53993056.
- ^Barden, 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.
External links[edit]
Media related toHaidomyrmexat Wikimedia Commons
