Sciency Thoughts: Myripoda

Showing posts with label Myripoda. Show all posts

Friday, 4 January 2019

Australobius tracheoperspicuus: A new species of Centipede from Guizhou Province, southwest China.

Centipedes (Myripoda) are carnivorous terrestrial Arthropods with elongate, multi-segmented bodies, having one pair of legs per body segment. The number of legs varies highly, from under 20 to over 300, though the number of pairs is always odd. The first pair of limbs is modified to form a pair of venomous forcipules (claws) used to subdue prey. There are around 3000 described species of extant centipedes, and it is though that the current number of species in existence is over 8000, though most of these are very small. Centipedes are thought to have been among the first Animal species to colonise the land, with a fossil record that dates back to the Late Silurian, around 430 million years ago.

In a paper published in the journal ZooKeys on 8 November 2018, Qing Li of the Guizhou Institute of Biology, Su-jian Pei of the School of Life Sciences at Hengshui University, Xuan Guo, also of the Guizhou Institute of Biology, and Hui-qin Ma of the Scientific Research Office at Hengshui University, and Hui-ming Chen, again of the Guizhou Institute of Biology, describe a new species of Centipede from Guizhou Province in southwest China.

The new species is placed in the genus Australobius, of which five species have previously been reported in China, and given the specific name tracheoperspicuus, in reference to a clearly visible trachea connected to the valve of the third tergite. The species is described from seven specimens, two adult males, one adult female, and four larval females. The adults of the species range from 17.43 to 19.24 mm in length, and are a pale yellow-brown in colour. The species was found on the walls and floor of two limestone caves in Weining Yi Hui and Miao Autonomous County.

Australobius tracheoperspicuus, male in dorsal view. Li et al. (2018).

Thursday, 23 August 2018

Permocrassacus novokshonovi and Permocryptops shelleyi: Two new species of Scolopendromorph Centipedes from the Permian of Russia.

Myriapods (Millipedes and Centipedes) are well represented in the fossil records of the Devonian and Carboniferous, but almost totally absent in that of the Permian, and quite rare in Mesozoic deposits, only becoming common on again in post-Cretaceous amber deposits. This is somewhat frustrating for palaeontologists who study the group, as almost all of the Devonian and Carboniferous fossils belong to extinct Millipede lineages, whereas most of the Mesozoic specimens belong to living groups, suggesting that these groups evolved either in the Permian or the Triassic.

In a paper published in the journal Acta Palaeontologica Polonica on 29 June 2018, Alexander Khramov of the Borissiak Paleontological Institute of Russian Academy of Sciences, and the Cherepovets State University, William Shear of Hampden-Sydney College, Randy Mercurio of the Engineering and Science Division at the Eastern Research Group, Inc., and Dmitry Kopylov, also of the Borissiak Paleontological Institute of Russian Academy of Sciences, and the Cherepovets State University, describe two new species of Scolopendromorph Centipedes from Permian deposits in Russia.

Scolopendromorph Centipedes include the largest known Myriapods today, and some of the largest Arthropods of any type, with some tropical species reaching over 30 cm in length and being feared for their highly toxic venom. Most species, however, are much smaller and many are found in temperate climates. All Scolopendromorphs, unfortunately, live in soil and leaf-litter habitats where there are numerous bacteria and fungi capable of digesting both chitin and the other proteins that make up arthropod cuticle, which, since they lack any mineralized tissues, gives them a very low chance of entering the fossil record. There have only been five previously reported fossil Scolopendromorphs from Palaeozoic and Mesozoic deposits, two from the Carboniferous Mazon Creek Lagerstätte of Illinois and three from the Crato deposits of Brazil.

The first new species described is named Permocrassacus novokshonovi, where 'Permocrassacus' refers to the Permian origin of the fossil and the encrassate (enlarged) nature of the last pair of legs of the specimen, and 'novokshonovi' honours Russian palaeoentomologist Viktor Novokshonov (1966–2003), for his work on the Tshekarda fossil site in the Perm Krai of Russia, where the specimen from which the species is described was discovered. The specimen is a 38 mm long Cenipede with 21 pedigerous (leg-bearing) segments, the last of which bears a greatly enlarged pair of legs, preserved on a split block as part and counter-part on a split slab from the Koshelevka Formation.

Scolopendromorph Chilopod Permocrassacus novokshonovi, from the Tshekarda locality, lower Permian of Russia. (A), (B) General view of part and counterpart, respectively. (C) Drawing compiled from part and counterpart. (D Head, antenna, and 1st leg. (E) Pairs of 20th and ultimate legs. Numbers indicate segments of trunk or legpairs. Khramov et al. (2018).

Enlarged final leg pairs are a feature of several modern groups of Scolopendromorph Centipedes. The final legs of the Cryptopidae are highly elongated, but no thicker than the other legs, those of the Scolopendridae are both elongate ans thickened, while those of the Plutoniumidae have been modified to form a large pair of forceps. Khramov et al. do not feel confident enough to assign Permocrassacus novokshonovi to any of these modern groups, but suggest that it may represent an intermediate state between the enlarged rear legs of the Scolopendridae and the forceps of the Plutoniumidae.

The second new species described is named Permocryptops shelleyi, where 'Permocryptops' derives from Permian and the modern Scolopendromorph Family Scolopocryptopidae, which the specimen resembles. The species is described from a single specimen preserved as part and counterpart on a spilt block from the Poldarsa Formation at Isady in the Vologda Oblast of Russia. The specimen preserves last 12 segments of the body of a Centipede estimated to have had 21 or 23 segments; the length of the preserved portion of the body is 17.7 mm.

Scolopendromorph Chilopod Permocryptops shelleyi, from the Isady locality, upper Permian of Russia. (A), (D) General view of part and counterpart (mirror-reversed), respectively. (B) Drawing compiled from part and counterpart. (C. Ultimate legs. (E) Pore ields and ventrodistal spines on the ultimate coxae. Abbreviations: po fi; pore field, sp, coxal spine; numbers in parentheses are segment numbers assuming 23 segments are present. Khramov et al. (2018).

Friday, 7 November 2014

Two new species of Flat-backed Millipede from Miocene Mexican amber.

Millipedes, Diplopoda, are highly successful soil dwelling Arthropods found in soil in all temperate and tropical regions. They are an ancient group, with a fossil record going back to the Silurian, but this is rather patchy as they appear to have poor preservational potential, and fossil Millipedes are typically only found in Lagerstätten deposits with exceptional preservation of small terrestrial animals, such as ironstone nodules and amber. Millipedes are thought to play a key role in soil formation, and to have played an important role in the development of ecological communities in the soil, so understanding the history of the group is considered important.

In a paper published in the journal PLoS One on 27 August 2014, a team of scientists led by Francisco Riquelme of Posgrado en Ciencias Biológicas and the Instituto de Física at the Universidad Nacional Autónoma de México, describe two new species of Flat-backed Millipedes from amber deposits in northern Chiapas State, Mexico. Chiapas Amber is thought to be between 23 and 15 million years old, and to have been produced in a Mangrove environment by trees of the genus Hymenaea. It is largely collected by artisanal miners.

The first new species is named Maatidesmus paachtun, where ‘Maat’ means ‘amber’ in Mayan, ‘-idesmus’ implies a Flat-backed Millipede and ‘paachtun’ means ‘stoney-backed’ in Mayan. The species is described from a single adult female specimen, preserved three dimensionally in amber.

Maatidesmus paachtun, general view, scale bar is 5 mm. Riquelme et al. (2014).

The specimen is 35.5 mm in length, and comprises the head and all 19 body segments. It has distinctive patterning on the dorsal surface of its body, comprising a large number of tiny lobes (which appear ‘stoney’ to Riquelme et al.), which is not seen in any close living relative.

Maatidesmus paachtun, 3D micro-CT reconstruction. (A–D): General view, scale bar is 5 mm. (E) Head, collum and first segments in lateral view, scale bar is 5 mm. (F) Dorsal view of first segments, scale bar is 2 mm. (G) Ventral view of head with a cross section of first segments, scale bar is 2 mm. (H) Collum, metaterga and paranota in dorsal view, scale bar is 3 mm. (I) Head and legs in dorsal view, scalebar is 3 mm. (J) Last segments in ventral and dorsal view (K), respectively, scale bar is 5 mm. All 3D images are expressed in virtual colours.Anatomical Abbreviations: ant, antennae; cl, collum; ct, cuticle; cw, claw; ep, epiproct; hc, head capsule; hyp, hypoproct; its, inner tissues; l, leg; lgs, longitudinal sulcus of the head capsule; mt, metatergite; mz, metazonite; p, paranota; pap, paraproct; par, preanal ring; pz, prozonite; s, trunk segment;spm, suture between the prozonite and metazonite. Riquelme et al. (2014).

The second new species described is named Anbarrhacus adamantis, where ‘Ánbar’ is Arabic for ‘amber’, ‘-rhacus’ is a common suffix for Millipedes and ‘adamantis’ means ‘diamond’ in Latin, a reference to the rhomboidal sculpting on the dorsal surface of the body segments. The species is described from a single male specimen, 19.8 mm in length, with a head and 17 body segments, preserved three dimensionally in amber.

Anbarrhacus adamantis, general view, scale bar is 5 mm. Riquelme et al. (2014).

Wednesday, 5 March 2014

A new species of Geophilomorph Centipede from Cretaceous Burmese amber.

In a paper published in the journal Palaeontology in January 2014, Lucio Bonato of the Dipartmento bi Biologia at the University of Padova, Gregory Edgecombe of the Department of Earth Sciences at the Natural History Museum and Alessandro Minelli, also of the Dipartimento di Biologia at the University of Padova, describe a new species of Centipede from the Late Cretaceous of Kachin State in the northeast of Myanmar (Burma).

The species is named Kachinophilus pereirai, where Kachinophilus means 'Geophilomorph from Kachin' and pereirai honours Luis Pereira, of the Museo de la Plata, an expert on Geophilomorph Centepedes. The species is described from four specimens preserved in amber from the Late Cretaceous of Kachin State, thought to be 98.79 million years old. Only one of the specimens is assigned a sex (male); this specimen being 21 mm in length with 43 leg-bearing segments.

Kachinophilus pereirai (A,B) Male specimen, complete body, in dorsal (A) and ventral (B) views. (C) Second specimen sex unknown, complete body, dorsal view. (D) Third specimen (only anterior part), ventral view. All scale bars 1 mm. Abbreviations: an, antenna; fo, forcipule; le-1, leg of the first pair; le-u, leg of the ultimate pair. Bonato et al. (2014).

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