Thaumastocheles

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Thaumastocheles
Thaumastocheles japonicus in the Enoshima Aquarium, Japan

Thaumastocheles japonicus in the Enoshima Aquarium, Japan

Systematics
Class : Higher crabs (Malacostraca)
Order : Decapods (decapoda)
Subordination : Pleocyemata
Partial order : Large crayfish (Astacidea)
Family : Lobster-like (Nephropidae)
Genre : Thaumastocheles
Scientific name
Thaumastocheles
Wood-Mason , 1874

Thaumastocheles is a genus of decapods (Decapoda) from the lobster-like family(Nephropidae). Thaumastocheles are widespreadin the deep sea of ​​the Caribbean and the western Pacific. The first species was discovered during the Challenger Expedition in 1873. Today five species are known.

description

The most noticeable features of these lobster-like are the very large right claws and the absence or only rudimentary presence of eyes. The eye stalks are immobile, Thaumastocheles are blind. Their coloring is entirely whitish ivory, sometimes tending to yellow. The possible hairs are light gray or cream-colored. Found animals had a maximum carapace length between 50 and 64.5 millimeters, the total length is then up to 155 millimeters. So they are relatively small compared to other lobster species.

In Thaumastocheles, the carapace has small spines just behind the formations of the eyes and antennae. It is hairy on its edges (front, abdomen and back), and in some cases the flanks of the carapace can show hair, but is otherwise hairless. Its surface is smooth to slightly grainy. The rostrum is flattened on the back, triangular and has up to six spines. The epistome is immovably connected to the carapace. The scaphocerites (the exopodites of the antennae) are about as long as the stems of the antennae.

The pleon is flattened, mostly strong. On somites 1 to 3 a clear ridge is visible on the side, which can show some peaks. Towards the back, this ridge becomes wider and more indistinct on somites 4 and 5. On the back, the tergites are rather smooth, without any special tips. The pleura of somites 2 to 5 are broad, slightly hairy and can be smooth or have small thorns. The telson is about as wide as the last abdominal thus and about square, sometimes a little longer than wide.

The chela of the first pereiopods are strongly asymmetrical. The right cheliped is very long and slender, the scissor fingers can be more than 4 times as long as the scissor hands and about twice as long as the carapace. The scissor fingers have numerous small teeth, interspersed with a few long teeth. The arrangement of the teeth is comb-shaped (pectinate). The left scissors are much shorter. There are small claws on the second and third pereiopods, the fourth is not chelated. There are small but distinct scissors on the fifth pair of legs. The pleopods are very hairy. The Endopod the uropods is short and wide and much smaller than the Exopod.

distribution and habitat

The range of Thaumastocheles is divided into two parts. One species ( Thaumastocheles zaleucus ) lives in the Caribbean Sea . Finds come from the coast of Yucatán , the east coast of Nicaragua, Sombreo, Grenada and the Florida Strait . The remaining species live in the western Pacific. Finds of these species come from Japan, Taiwan, the South China Sea , the Philippines, Indonesia, the Solomon Islands , Papua New Guinea, as well as New Caledonia and Madagascar .

The species of Thaumastocheles are inhabitants of the deep sea at sea depths between 640 and 1767 meters. Because of the great depths, little is known about the habitat and behavior. Gray ooze was found in the nets used to catch specimens of the genus. The sites are described as soft, muddy and sandy. A burrowing way of life is assumed, as is typical for Thalassinidea . Other authors assume with regard to the rather bulky large scissors that Thaumastocheles do not live completely in self-dug cave passages, but are only buried with the rear parts of the body and the scissors and antennae are outside the caves. Forminifera living on crustaceans were found almost exclusively in these areas, which would support this thesis. The bright color of the crabs is still an indicator of a burrowing way of life.

Systematics

Phylogeny of species according to Chang, Chan and Ahyong 2014
  Thaumastocheles  




T. japonicus  holotype, Japan


   

T. Dochmiodon  Japan



   

T. japonicus  Taiwan


   

T. Dochmiodon  holotype, Taiwan




   

T. massonktenos


   

T. zaleucus




   

 T. bipristis



Template: Klade / Maintenance / Style
In T. japonicus and T. dochmiodon supplemented by type and material origin

Thaumastocheles is closely related to the genera Thaumastochelopsis and Dinochelus . These three genera form a monophyletic group within the lobster-like. Their common feature is the extremely different pair of scissors of the first pereiopods . The right scissors are greatly elongated and the teeth on the long, slender scissor fingers are arranged in a comb shape (pectinate). In addition, in contrast to all other lobster-like species, the telson is square and the fifth pereipod has scissors. The sister group of Thaumastocheles is Thaumastochelopsis . The genera differ mainly in the shape of the stalk eyes , which are mobile in Thaumstochelopsis , and the exopodites of the maxillae.

The genus Thaumastocheles includes five species:

A phylogenetic investigation based on ribosomal RNA and mitochondrial DNA confirms four clades within the Thaumastocheles (see cladogram). However, it also shows that crabs from Taiwan, described as Thaumastocheles nochmiodon , are more closely related to Thaumastocheles japonicus from Taiwan than to individuals of Thaumastocheles nochmiodon from Japan. Thaumastocheles nochmiodon is therefore probably not a species in its own right and should be added to Thaumastocheles japonicus . The four clades basically match the geographical distribution of the species: Thaumastocheles japonicus near Japan, Taiwan and in the South China Sea; Thaumastocheles bipristis in the Philippines and Indonesia, Thaumastocheles massonktenos from the South China Sea to Madagascar and north of Australia and Thaumastocheles zaleucus in the Caribbean. The species can be distinguished morphologically by means of scissors and their teeth, with the surface properties of the pleon, especially its pleura, as well as with the shape of the rostrum and the eye stalks.

Research history and taxonomy

James Wood-Mason 1876, first descriptor of Thaumstocheles

The first specimen of this genus was discovered during the Challenger expedition . On March 15, 1873, a complete female and fragments of a second animal were caught with a trawl from a depth of approx. 823 meters (450 nautical fathoms ) off the Caribbean island of Sombrero . While on board the HMS Challenger , the expedition member Rudolf von Willemoes-Suhm described the cancer in November 1873 and named it Astacus zaleucus . This report was not published until 1875. As early as July 1873, a report by the expedition leader Charles Wyville Thomson appeared in Nature , in which the cancer was mentioned. Thompson is therefore considered to be the first to describe Astacus zaleucus .

Even Rudolf von Willemoes-Suhm was not sure about the assignment of his catch to Astacus and after his return he wanted to compare the found individual with others of the genus Astacus . However, he died in 1875 before Tahiti. On August 5, 1874, at a meeting of the Asiatic Society of Bengal , James Wood-Mason presented drawings of blind crabs, among others. a. also one of Willemoes-Suhm's Astacus zaleucus . He doubted that it was an astacid and first referred to the cancer as Thaumastocheles zaleucus . This name was published in the Proceedings published by the Society , which is why Wood-Mason is considered to be the first descriptor of the genus. Charles Spence Bate had the task of scientifically evaluating the crustaceans of the Challenger expedition. In 1888 his Report on the Crustacea Macrura dredged by HMS Challenger during the years 1873 and 1876 could be completed. He adopted Wood-Mason's name and also described the Thaumastochelidae family. According to a phylogenetic analysis of mitochondrial DNA , the Thaumastochelidae are monophyletic, but lie within the lobster-like species , which is why the family status is no longer recognized.

Thaumastocheles was considered rare. A total of only seven specimens of Thaumastocheles zaleucus and Thaumastocheles japonicus were scientifically recorded until about 1991. In addition to deep-sea expeditions, the Thaumastocheles finds increased thanks to deep-sea fishing . Why in 1999 Thaumastocheles nochmiodon and in 2014 Thaumastocheles massonktenos and Thaumastocheles bipristis could be described. The first descriptors of the two last-mentioned taxa , Su-Ching Chang, Tin-Yam Chan, Shane T. Ahyong, were also able to carry out DNA barcoding with all known species . The researchers were even able to include the holotype of Thaumastocheles japonicus found in 1898 in their investigation. Thereby they established that Thaumastocheles nochmiodon is most likely to be attributed to Thaumastocheles japonicus (see cladogram). From Thaumastocheles dochmiodon was found previously only males of Thaumastocheles japonicus with one exception only females, so the authors assume that this sexual dimorphism and the males polymorphism might be impaired.

literature

Individual evidence

  1. ↑ a b c d e f g h i j k l Su-Ching Chang, Tin-Yam Chan, Shane T. Ahyong: Two new species of the rare lobster genus Thaumastocheles Wood-Mason, 1874 (Reptantia: Nephropidae) discovered from recent deep-sea expeditions in the Indo-West Pacific . In: Journal of Crustacean Biology . tape 34 , no. 1 , 2014, p. 107-122 , doi : 10.1163 / 1937240X-00002201 .
  2. ↑ a b c d e f g h i Tin-Yam Chan, Michèle de Saint Laurent: The Rare Lobster Genus Thaumastocheles (Decapoda: Thaumastochelidae) from the Indo-Pacific, with Description of a New Species . In: Journal of Crustacean Biology . tape 19 , no. 4 , 1999, p. 891-901 .
  3. ↑ a b c d e f g h i Lipke B. Holthuis: The Lobsters of the Superfamily Nephropidea of ​​the Atlantic Ocean (Crustacea: Decapoda) . In: Bulletin of Marine Science . tape 24 , no. 4 , 1974, p. 723-884 ( PDF, 16Mb [accessed April 3, 2015]).
  4. ↑ a b Dale Tshudy, Rafael Robles, Tin-Yam Chan, Ka Chai Ho, Ka Hou Chu, Shane T. Ahyong, Darryl L. Felder: Phylogeny of marine clawed lobster families Nephropidae Dana, 1852, and Thaumastochelidae Bate, 1888, based on mitochondrial genes . In: Joel W. Martin, Keith A. Crandall, Darryl L. Felder (Eds.): Decapod Crustacean Phylogenetics . CRC Press, 2009, ISBN 1-4200-9258-8 , pp. 357–368 ( PDF, 1.2Mb [accessed April 3, 2015]).
  5. ↑ a b Shane T. Ahyong, Ka-Hou Chu, Tin-Yam Chan: Description of a new species of Thaumastochelopsis from the Coral Sea (Crustacea: Decapoda: Nephropoidea) . In: Bulletin of Marine Science . tape 80 , no. 1 , 2007, p. 201–208 ( abstract and link to the full text [accessed on April 3, 2015]).
  6. ↑ Shane T. Ahyong, Tin-Yam Chan, Philippe Bouchet: Mighty claws: a new genus and species of lobster from the Philippine deep sea (Crustacea, Decapoda, Nephropidae) . In: Zoosystema . tape 33 , no. 3 , 2010, p. 525-535 , doi : 10.5252 / z2010n3a11 .
  7. ↑ Tin-Yam Chan: Thaumastocheles. World Register of Marine Species, 2015, accessed April 3, 2015 .
  8. ^ Rudolf von Willemoes-Suhm: On some Atlantic Crustacea from the "Challenger" Expedition . In: Transactions of the Linnean Society of London . ser. 2, no. 1 , 1875, p. 23-69 ( page 48 via biodiversitylibrary.org [accessed April 3, 2015]).
  9. ^ Charles Wyville Thomson: Notes from the "Challenger" . In: Nature . tape 8 , 1873, p. 246-249 , doi : 10.1038 / 008246a0 .
  10. ↑ James Wood-Mason: Blind Crustacea . In: Proceedings of the Asiatic Society of Bengal . 1874, p. 180-181 ( page 180 via biodiversitylibrary.org [accessed April 3, 2015]).
  11. ^ Charles Spence Bate: Report on the Crustacea Macrura dredged by HMS Challenger during the years 1873 and 1876 . In: Charles Wyville Thomson, John Murray (Ed.): Report on the scientific results of the voyage of HMS Challenger during the years 1873-76 under the command of Captain George S. Nares and the late Captain Frank Tourle Thomson, RN Zoology v .24, 1888 ( Thaumastochelidae. P. 46 via biodiversitylibrary.org [accessed April 3, 2015]).

Web links

Commons : Thaumastocheles  - collection of images, videos and audio files
  • Shane T. Ahyong: Deep-sea surprise. Australian Museum, March 4, 2014, accessed April 1, 2015 (blog article about the discovery of T. bipristis and T. massonktenos including pictures).