Trigonopterus

Trigonopterus is a genus of flightless weevils placed in the Cryptorhynchinae of Curculionidae. It is distributed in the area between Sumatra, Samoa, the Philippines, and New Caledonia. About 90 species had been formally described until March 2013, when a single paper more than doubled this number,[1] agreeing with previous studies[2] and a systematic barcoding study[3] that many more species have yet to be described. As of November 2019, there were 451 described species.

Trigonopterus
Trigonopterus vandekampi from New Guinea
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Coleoptera
Family: Curculionidae
Subfamily: Cryptorhynchinae
Genus: Trigonopterus
C.A.A.Fauvel, 1862

The center of its diversity appears to be New Guinea where 51 or more species can be found in a single locality.[4] Many of them are very similar to each other, but male genital characters and DNA barcoding allow a safe identification.

In January 2016, a paper was published that revised the Australian species within this genus. That paper described 24 new species and indicated the potential for more research into undescribed Australian species within this genus.[5][6]

In April 2016, a paper was published that described four new species in this genus from the island of New Britain. The paper postulated that more species of this genus presently unknown to science may exist on the island. It emphasised the importance of prioritising further research due to the ongoing destruction of the habitat of these species.[7]

In March 2019, a further paper was published describing 103 new species from Sulawesi, where only one species (T. fulvicornis) had previously been recorded.[8]

The genus can be diagnosed among wingless cryptorhynchine weevils by the absence of a metanepisternum and by a synapomorphic structure of the tarsus with minute claws and a deeply incavated articulation of tarsomere 4. The metathoracic spiracle located externally at the side of the metaventrite is a unique feature and may ensure sufficient respiration during thanatosis.[9]

Trigonopterus species inhabit primary tropical forests, both on foliage and edaphic in the litter layer. They have a marked tendency to endemism with many species only known from a single locality. Their primary defence against predators is apparent death or thanatosis. An animated 3D model of a Trigonopterus weevil reveals a number of mechanisms to maintain a stable defensive position.[10]

Biological screw joint
Main article: Biological screw joint

The arthropod hip-leg joint consists of two parts - the coxa (or the hip) and the trochanter (or the head of the arthropod leg femur).[11] The coxa, in the case of Trigonopterus oblongus, resembles a nut, and it has a thread running along its inner surface with an angular span of 345°.[12][11] The trochanter resembles the screw.[11] It is rod-shaped with a large external spiral flange, having an angular span of 410°, in excess of a full circle, which functions as a thread.[12] When the leg muscles of a beetle are stretched, the screw turns. Though the screw-thread provide for very large angular rotation, the front legs are capable of rotating by 90°, while their hind legs can rotate by 130°.[13]

Evolution

The screw-and-nut system has now been found to be present in all 15 weevil species examined by the scientists and appears to be a hitherto unknown anatomical feature of weevils.[14][13] It has been estimated that weevils evolved this system about 100 million years ago. It is surmised that the development of this feature provided additional flexibility which permitted weevils to improve their climbing abilities, helped them keep steady when at rest, and to give a stronger leverage for piercing by the snout.[14]

Species
100 Trigonopterus species described in 2013
  • The lateral aspect on thorax of the weevil Trigonopterus oblongus. In this genus, the metanepisternite is absent and the elytron touches the metaventrite (indicated).
  • Metatarsus of weevil Trigonopterus sp. (from Java); scanning electron micrograph
  • Diagram of the biological screw in the weevil Trigonopterus oblongus

References
  1. Riedel, A.; Sagata, K.; Surbakti, S.; Tänzler, R.; Balke, M. (2013). "One hundred and one new species of Trigonopterus weevils from New Guinea". ZooKeys (280): 1–150. doi:10.3897/zookeys.280.3906. PMC 3677382. PMID 23794832.
  2. Alexander Riedel (2010). "One of a thousand - a new species of Trigonopterus (Coleoptera, Curculionidae, Cryptorhynchinae) from New Guinea". Zootaxa. 2403: 59–68. doi:10.11646/zootaxa.2403.1.5.
  3. Riedel, A.; Sagata, K.; Suhardjono, Y. R.; Tänzler, R.; Balke, M. (2013). "Integrative taxonomy on the fast track - towards more sustainability in biodiversity research". Frontiers in Zoology. 10 (1): 15. doi:10.1186/1742-9994-10-15. PMC 3626550. PMID 23537182.
  4. Alexander Riedel, Daawia Daawia & Michael Balke (2010). "Deep cox1 divergence and hyperdiversity of Trigonopterus weevils in a New Guinea mountain range (Coleoptera, Curculionidae)". Zoologica Scripta. 39 (1): 63–74. doi:10.1111/j.1463-6409.2009.00404.x.
  5. Riedel, Alexander; Tänzler, Rene (21 January 2016). "Revision of the Australian species of the weevil genus Trigonopterus Fauvel". ZooKeys (556): 97–162. doi:10.3897/zookeys.556.6126. PMC 4740874. PMID 26877696.
  6. Sheikh, Knvul. "Hiding in Plain Sight: 24 New Beetle Species Discovered in Australia". Live Science. Retrieved 21 January 2016.
  7. Van Dam, Matthew H.; Laufa, Raymond; Riedel, Alexander (21 April 2016). "Four new species of Trigonopterus Fauvel from the island of New Britain (Coleoptera, Curculionidae)". ZooKeys (582): 129–141. doi:10.3897/zookeys.582.7709. PMC 4857049. PMID 27199589.
  8. Riedel, Alexander; Narakusumo, Raden Pramesa (7 March 2019). "One hundred and three new species of Trigonopterus weevils from Sulawesi". ZooKeys (828): 1–153. doi:10.3897/zookeys.828.32200. PMC 6418079. PMID 30940991.
  9. van de Kamp, T.; Cecilia, A.; dos Santos Rolo, T.; Vagovič, P.; Baumbach, T.; Riedel, A. (2015). "Comparative thorax morphology of death-feigning flightless cryptorhynchine weevils (Coleoptera: Curculionidae) based on 3D reconstructions". Arthropod Structure & Development. 44 (6): 509–523. doi:10.1016/j.asd.2015.07.004. PMID 26259678.
  10. Van De Kamp, T.; Dos Santos Rolo, T.; Vagovič, P.; Baumbach, T.; Riedel, A. (2014). "Three-Dimensional Reconstructions Come to Life – Interactive 3D PDF Animations in Functional Morphology". PLOS ONE. 9 (7): e102355. doi:10.1371/journal.pone.0102355. PMC 4100761. PMID 25029366.
  11. Ross, Valerie (30 June 2011). "Zooming in on Beetles' Knees, Biologists Find Tiny Screws and Nuts". Discover magazine. Kalmbach Publishing Co. Retrieved 22 May 2011.
  12. van de Kamp, Thomas; Vagovic, Patrik; Baumbach, Tilo; Riedel, Alexander (1 July 2011). "A Biological Screw in a Beetle's Leg". Science. 333 (6038): 52. doi:10.1126/science.1204245. PMID 21719669. S2CID 8527127.
  13. Brown, Mark (5 July 2011). "Weevil Has Nuts and Bolts in Its Legs". Wired Science. Condé Nast Digital. Retrieved 25 July 2011.
  14. Karlsruhe Institute of Technology (source) (5 July 2011). "Nature uses screws and nuts: Previously unknown musculoskeletal system discovered in weevils". ScienceDaily. Retrieved 25 July 2011.
  15. Riedel, Alexander; Narakusumo, Raden Pramesa (7 March 2019). "One hundred and three new species of Trigonopterus weevils from Sulawesi". ZooKeys (828): 1–153. doi:10.3897/zookeys.828.32200. ISSN 1313-2989. PMC 6418079. PMID 30940991.

This article is issued from Wikipedia. The text is licensed under Creative Commons - Attribution - Sharealike. Additional terms may apply for the media files.