Atyaephyra desmarestii

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Atyaephyra desmarestii
Systematics
Class : Higher crabs (Malacostraca)
Order : Decapods (decapoda)
Partial order : Caridea
Family : Freshwater shrimp (Atyidae)
Genre : Atyaephyra
Type : Atyaephyra desmarestii
Scientific name
Atyaephyra desmarestii
( Millet , 1831)

Atyaephyra desmarestii is a species of shrimp found in freshwater and brackish water in the western Mediterranean. It was introducedto Central Europeas a neozoon by humans. It is the only freshwater shrimp in most of the surface waters of Central Europe.

description

The species is a small type of shrimp, the carapace reaches a length of 6.8 millimeters in the male and 8.5 millimeters in the female. The animals are whitish-translucent, sometimes a little yellowish in color. In front of the carapace sits a long and slender rostrum that is longer than the peduncles of the antennae, but shorter than the carapace. The rostrum is straight and about three to seven times as long as it is wide, it is toothed on both sides. The upper edge bears 23 to 28 small teeth, the last 2 to 4 of which sit backwards on the top of the carapace. On the underside, there are 5 to 10 coarser teeth only in the outer (distal) half. The smooth carapace has two pairs of thorns on the front edge, the supraorbital and antennal thorns. The supraorbital spines sit above the eye opening (the so-called orbital pit), to the side of the rostrum, the antennal near the lower edge of the eye opening. Otherwise the carapace looks almost straight cut off at the front end with right-angled corners. The abdomen or pleon consists of five segments and the telson . Their side sections (pleura) are broadly rounded in the first three in side view, in the fourth and fifth pointed. The telson is just as long or slightly longer as the sixth segment. A row of eight to nine strong thorns sit on its broadly rounded rear edge.

Two rather large, short-stalked complex eyes can be seen on the head, the stalk of which is shorter than the diameter of the eye. In the similar, stygobiont genus Troglocaris , the eyes are regressed. Of the two pairs of antennas, the front one has a long stem section that is slightly shorter than the rostrum. It has two flagella of moderate length. At the base of the second antennae sits a long, scale-like appendix, the scaphocerite , which is longer than the rostrum. The scourge of the second antennae is more than body length. From below, three trunk extremities can be seen, which connect to the head section as maxillipedes and serve for food intake. This is followed by five pairs of striding legs (pereiopods). The first two pairs of pereiopods are designed as small claws ( chela ). A long tuft of hair on the tip of the scissor finger is typical of the genus. Only these two pairs of legs have the exopodites of the cancerous split leg , on the back three it has regressed without any residue. The carpus of the first two pairs of pereiopods has a distal recess on the upper side. Long and slender extremities, the pleopods, also sit on the first two abdominal segments. On the abdomen, the uropods form a short tail fan with the telson. Your endopod is about as long as the exopod, both of which protrude above the telson.

The species Neocaridina davidi , which is also introduced as a neozoon and is popular with aquarists and previously known from the Erft system, North Rhine-Westphalia, is easy to distinguish in terms of numerous characteristics, including the supraorbital tooth on the carapace, which is missing in this species Lower anterior angle of the carapace formed a tooth. In addition, this species, especially the aquarium forms, is often spotted or marked extensively in red.

Development and life cycle

The species is annual, in parts of its range two-year-old. In the laboratory, individuals from the Rhine usually lived for 12 to 15 months, a maximum of 29 months, and some animals were sometimes hibernated a second time. Even perennial individuals can only reproduce once (they are then semivoltine ), they become slightly larger than annuals. Egg-bearing females have been observed in North Africa from March to October and in France from April to August. The females each carry around 300 to 400, up to a maximum of 1,500 eggs. The number of adults falls sharply in summer, the maximum of young animals is in late summer. The young hardly live in open water, they seek shelter between aquatic plants or under overhanging roots.

The development takes place via two different forms of larvae. A little more than a millimeter long zoea hatches from the egg . The first two stages do not ingest any food, they feed on the yolk supply from the egg. The sixth Zoea stage sheds its skin into a megalopa, which is followed by a young animal with the sexually mature animals of the corresponding morphology. The first larval stages are completed in three to four days, the later in nine to ten days.

distribution

The species, in the view of modern taxonomic revisions, is naturally common in the western Mediterranean. The distribution area includes the coastal North Africa (Morocco and Tunisia), the Iberian Peninsula , southern France and Italy, including the islands of Corsica, Sardinia and Sicily. An island-like occurrence exists in north-western Greece, possibly due to introduction. Through the construction of shipping canals across earlier watersheds, and probably also through carry-over in the ballast water of ships, the species was introduced as a neozoon in northern France, from where it spread further eastwards. It was first detected in Paris in 1843, in Belgium, 1888 and in Holland in 1916, Metz was reached in 1925 and Strasbourg in 1929. The first German find from 1932 comes from Rees on the Lower Rhine. In 1936 it reached Hanover via the Mittelland Canal . Via the later rebuilt Main-Danube Canal , it was able to penetrate from the Main (first record in 1983) into the Danube catchment area. The first record from the Danube dates from 1997. The first discovery was made here for Austria as early as 1998; Penetrated estuary in the Black Sea. It reached the Czech Republic in 2007 via the Elbe. The first record for Poland, from the Oder, took place in 2002.

ecology

The species lives in stagnant and slowly flowing surface waters. In rivers, she prefers backwaters or flow-calmed zones, she has a particular preference for shipping canals or river sections regulated by dams for shipping. It prefers oxygen-rich, exposed water with rich vegetation. In the saprobic system , with an indicator value of 1.9, it is a pointer species of water quality class II. It is relatively tolerant of pollution by toxic substances. The freshwater shrimp is omnivorous . In addition to algae, plankton, small aquatic animals such as tubeworms and detritus , it can also feed on fallen leaves that have fallen into the water. They themselves become prey for swimming beetles, dragonfly larvae and fish such as perch .

Systematics and taxonomy

The taxonomy of the species is confused. Animals belonging to the species (according to today's view) were first described by Constantine S. Rafinesque-Schmaltz in 1814, after animals from Sicily, under the name Symethus fluviatilis . This name was later suppressed as a forgotten name ( nomen oblitum ) by resolution of the ICZN . Pierre-Aimé Millet discovered similar animals in France in 1831, which in his opinion belonged to a different species, which he named Hippolyte desmarestii . Félix António de Brito Capello discovered other animals near Coimbra in Portugal in 1867, for which he described the species Atyaephyra rosiana . Arnold Edward Ortmann noted in 1890 that Hippolyte desmarestii and Atyaephyra rosiana were in fact the same species for which he introduced the name Atyaephyra desmarestii . Type species of the genus is therefore Atyaephyra rosiana, a synonym of Atyaephyra desmarestii. The species name was written as desmaresti (with only an i) in most of the older publications .

Thereafter, the systematists were long of the view that the genus Atyaephyra would only include this one species, but for which a number of varieties and subspecies were given, whose status and delimitation were, however, disputed. It was not until the 2000s that the earlier collective species was split up, mainly through genetic research. According to this, the animals of the eastern Mediterranean that were previously included in this species actually belong to a number of other species that can hardly be differentiated according to morphological criteria ( cryptospecies ). The species was initially split into seven new species, one of which was later synonymous with Atyephyra desmarestii . However, other cryptic species may exist.

Individual evidence

  1. ↑ Ch. Anastasiadou, M.-S. Kitsos, A. Koukouras (2006): Redescription of Atyaephyra desmarestii (Millet, 1831) (Decapoda, Caridea, Atyidae) based on topotypical specimens. Crustaceana 79 (10): 1195-1207.
  2. ↑ a b c d Magdalini Christodoulou, Aglaia Antoniou, Antonios Magoulas, Athanasios Koukouras (2012): Revision of the freshwater genus Atyaephyra (Crustacea, Decapoda, Atyidae) based on morphological and molecular data. ZooKeys 229: 53-110. doi : 10.3897 / zookeys.229.3919
  3. ↑ Werner Klotz, Friedrich Wilhelm Miesen, Sebastian Hüllen, Fabian Herder (2013): Two Asian fresh water shrimp species found in a thermally polluted stream system in North Rhine-Westphalia, Germany. Aquatic Invasions 8 (3): 333-339. doi : 10.3391 / ai.2013.8.3.09
  4. ↑ a b c Gerhard Schoolmann, Frank Nitsche, Hartmut Arndt (2015): Aspects of the life span and phenology of the invasive freshwater shrimp Atyaephyra desmarestii (Millet, 1831) at the northeastern edge of its range (Upper Rhine). Crustaceana 88 (9): 949-962. doi : 10.1163 / 15685403-00003470
  5. ↑ Ch. Anastasiadou, A. Ntakis, ID Leonardos (2011): Larval development of the freshwater shrimp Atyaephyra desmarestii (Millet, 1831) sensu lato (Decapoda: Caridea: Atyidae) and morphological maturation from juveniles to adults. Zootaxa 2877: 41-54.
  6. ↑ a b J. E. Muñoz, JE Raso, A. Rodríguez, JA Cuesta (2014): Cryptic speciation of Greek populations of the freshwater shrimp genus Atyaephyra de Brito Capello, 1867 (Crustacea, Decapoda), evidence from mitochondrial DNA. Zootaxa 3790 (3): 401-424. doi : 10.11646 / zootaxa.3790.3.1
  7. ↑ a b Thomas Tittizer, Franz Schöll, Mechthild Banning, Ame Haybach, Michael Schleuter (2000): Aquatic invasive species in benthic invertebrates of inland waterways in Germany. Lauterbornia 39: 1-72.
  8. ↑ Otto Moog, Hasko Nesemann, Andreas Zitek, Andreas Melcher (1999): First record of the freshwater shrimp Atyaephyra desmaresti (Millet 1831) (Decapoda) in Austria. Lauterbornia 35: 67-70.
  9. ↑ Michal Straka, Jan Špaček (2009): First record of alien crustaceans Atyaephyra desmarestii (Millet, 1831) and Jaera istri Veuille, 1979 from the Czech Republic. Aquatic Invasions 4 (2): 397-399. doi : 10.3391 / ai.2009.4.2.18
  10. ↑ Michał Grabowski, Krzysztof Jażdżewski, Alicja Konopacka (2005): Alien Crustacea in Polish waters (Part I). Oceanological and Hydrobiological Studies 34, Supplement 1: 43-61.
  11. ↑ Profile of the European freshwater shrimp Atyaephyra desmaresti. At: neobiota.info. Retrieved February 17, 2020.
  12. Jump up ↑ Sofia Duarte, Maria Leonor Fidalgo, Cláudia Pascoal, Fernanda Cássio: The role of the freshwater shrimp Atyaephyra desmarestii in leaf litter breakdown in streams. Hydrobiologia 680 (1): 149-157. doi : 10.1007 / s10750-011-0912-0