Thymops birsteini
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| ( Zarenkov & Semenov , 1972) |
Thymops birsteini is a species of decapod from the lobster family. The lobster species described in 1972 is common in the deep sea of the South Atlantic near Argentina and Chile.
description
The rostrum of Thymops birsteini is narrow and extends far beyond the antenna bases (antennal peduncles). It has thorns on the sides, but not on the abdomen or back. The surface of the rostrum has a central depression that continues lengthways over the entire carapace as a flat line. As with the species Thymopsis nilenta, there are two ridges running parallel to the depression from about the middle on the rostrum, which are provided with seven or eight sharp points.
The slightly hairy carapace is generally irregularly finely granulated. The individual segments ( somites ) of the pleon have a transverse depression. The telson is significantly longer than it is wide and longer than the sixth thus. The back surface of the Telsons is granulated and has two blunt and rather inconspicuous ridges. The eyes are rather small, reduced and not pigmented, but mobile. The antenna exopodite (Scaphocerite) is missing. The exopodite of the second maxillipede is reduced and without a flagellum, that of the third is very small.
The large scissors on the first pair of striding legs are the same, relatively large and covered with many thorns or nodules. The scissor fingers are about as long as the scissors hand. The scissor fingers taper towards the end, are bent inward and cross each other when the scissors are closed. There are very small scissors on the second and third pair of striding legs, the fourth and fifth are scissorless. The second and third pairs are very occasionally provided with hair.
In males, the segments of the first pair of swimming legs are immovably fused, the endo- and exopodites of the second to fifth pairs of swimming legs are relatively slender. On the endopodite of the second pair, the "Appendix masculina", a kind of bracket-like appendix, is relatively short. In females, the first pair consists of two movable segments, the one on the body (basal) being shorter. The remaining swimming legs of the females are similar to those of the third to fifth pair of males.
The uropods are relatively wide and have a longitudinal ridge in the middle. The outer edge of the endopodites ends in a single point. The exopodite has a clear diaeresis, a transverse depression that has about 20 small tips towards the front.
Males and females are roughly the same size. The maximum carapace length is about 13 cm and a weight of 300 g. The smallest sexually mature females had a carapace length of 3 cm. Females with freshly spawned eggs were caught in both spring and autumn. The largest number of eggs in a female was 378, the number of eggs correlated with body size. Eggs are initially yellowish-orange and have sizes of up to 2 mm. Shortly before hatching, the eggs are about 3 mm in size and yellowish-brown. When hatched, the larvae have a carapace length of about 2 mm. In contrast to other lobsters, whose larvae change directly into a planktonic way of life, newly hatched larvae are initially still attached to the females' swimming legs.
distribution and habitat
Thymops birsteini is native to the continental shelf and the deep sea on the coasts of Argentina, Uruguay and Chile as well as north, east and southeast of the Falkland Islands and east of South Georgia . The distribution area is in the Pacific south of 51 ° S and in the Atlantic south of 37 ° S to a maximum of 57 ° S. The depths of the sea range from 175 m to a maximum of 1662 m, with the vast majority of catches coming from depths between 1000 m and 1400 m.
Due to its large distribution area, Thymops birsteini is classified as "not endangered" (least concern). In addition, this species has only been fished as by-catch so far, although it may be of commercial interest.
The habitat is characterized by soft mud, where Thymops birsteini stays in self-dug caves during the day. Enemies of this lobster species are u. a. the black hake ( Dissostichus eleginoides ), grenadier fish of the genus Macrourus and the squid Onykia ingens .
Systematics and taxonomy
The first description of Thymops birsteini was carried out by the Russian researchers NA Zarenkov and VN Semenov as Nephropides birsteini . Lipke Holthuis established the genus Thymops with this one species and, together with the newly described genus Thymopsis Holthuis, divided it into a separate subfamily within the lobster-like species, the Thymopinae Holthuis, 1974 . However, the results of a phylogenetic investigation do not support the division of the lobster family into subfamilies, which is why these are no longer in use. Shane Ahyong and co-authors described the species Thymops takedai in 2012 , so the genus is no longer monotypical . In contrast to Thymops takedai, Thymops birsteini has a smooth rostrum on the belly, the exopodites of the third maxillipede have flagella and the carapace has different ornamentation.
Thymops differs from the closely related genus Thymopsis mainly in the presence of exopodites on the second and third maxillipedas . Together with the Kaphummer ( Homarinus capensis ) and the genus Thymopides , Thymops forms a clade within the lobster-like species.
literature
Individual evidence
- ↑ a b c d e f g 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 ( nhm.org [PDF; 16.0 MB ; accessed on July 1, 2012]).
- ↑ a b c Vladimir Laptikhovsky, Pablo Reyes: Distribution and reproductive biology of a subantarctic deep-sea lobster, the Patagonian lobsterette Thymops birsteini (Zarenkov and Semenov, 1972) (Decapoda, Astacidea, Nephropidae) . In: Journal of Natural History . tape 43 , no. 1-2 , 2009, pp. 35-46 , doi : 10.1080 / 00222930802567099 .
- ^ A b Lipke B. Holthuis: Marine Lobsters of the World . An Annotated and Illustrated Catalog of Species of Interest to Fisheries Known to Date. Ed .: Food and Agriculture Organization (= FAO Fisheries Synopsis . Volume 125 ). Rome 1991, ISBN 978-92-5103027-1 ( fao.org ).
- ↑ Thymops birsteini in the endangered Red List species the IUCN 2012. Posted by: Wahle, R., 2011. Retrieved on July 1, 2012th
- ↑ 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 ( nhm.org [PDF; 1,2 MB ; accessed on July 1, 2012]).
- ↑ ST Ahyong, WR Webber, TY Chan: Thymops takedai, a new species of deepwater lobster from the Southwest Atlantic Ocean with additional records of 'thymopine' lobsters (Decapoda, Nephropidae) . In: H. Komatsu, J. Okuno, K. Fukuoka (eds.): Studies on Eumalacostraca: a homage to Masatsune Takeda . Brill, 2012, p. 49–61 , doi : 10.1163 / 9789004202894_004 ( full text in the Google book search).
Web links
- Arianna Masello: Langosta oceánica. Direccion nacional de Recursos acuatico - Uruguay, accessed July 1, 2012 (Spanish, picture and description of the species).
- Thymops birsteini (Zarenkov & Semenov, 1972). In: Antarctic Invertebrates. Smithsonian National Museum of Natural History, accessed July 1, 2012 (English, picture and description of the species).