Criodrilidae

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Criodrilidae
External genital organs of Criodrilus lacuum. Drawing from Barrie GM Jamieson (2006): Non-leech Clitellata.

External genital organs of Criodrilus lacuum . Drawing from Barrie GM Jamieson (2006): Non-leech Clitellata.

Systematics
Over trunk : Lophotrochozoa (Lophotrochozoa)
Trunk : Annelids (Annelida)
Class : Belt worms (Clitellata)
Subclass : Little bristle (Oligochaeta)
Order : Earthworms in the broader sense (Crassiclitellata)
Family : Criodrilidae
Scientific name
Criodrilidae
Vejdovský , 1884

Criodrilidae (from the Greek κριός kriós "ram" and δρίλος drílos "earthworm") is the name of a family of little bristles in the order of Crassiclitellata (earthworms in the broader sense), the three currently known and accepted species of which are common in Eurasia and North Africa and live in the soil in fresh water .

features

The body of the Criodrilidae has a rectangular cross-section, at least from the 9th segment, on the edges of which there are four pairs of bristles per segment , and has no dorsal pores. The prostomium (mouth lobe) is zygolobic, so it lies against the peristomium (mouth segment) without a dorsal process.

The intestinal canal has neither gizzards nor calcified glands, but there may be thickenings in the esophagus between the 5th and 7th segment and in the midgut between the 15th and 20th or 21st segment, as well as a typhlosolis . The midgut begins between the 15th and 20th segments. The closed blood vessel system of the Criodrilidae has lateral hearts from the 7th (sometimes 6th) to the 11th segment, while in the posterior segments the lateral vessels branch out into dense capillary networks and thus supply the internal organs and the skin. There are three large longitudinal vessels: a dorsal, an abdominal and a neural vessel. The large nephridia are well developed, but are absent in the first segments.

The very extensive, front and rear but only indistinctly demarcated and therefore inconspicuous clitellum of the hermaphrodite is ring-shaped, without pubertal tuberosities and usually extends from the 16th, sometimes also from the 14th or 15th to the 45th segment, but can occur in bivouacs and Hydrilus may also be shorter. The only pair of female genital orifices is always on the 14th segment , the only pair of male genital orifices in Criodrilus on porophores on the 15th and in Biwadrilus on the 13th segment and is connected to the prostate ( Bursae ejaculatoriae ). Receptacula seminis are absent; instead, horn-, tube- or sac-shaped pseudospermatophores (referred to by Hoffmeister as “ penes ”) are formed in the male genital orifices . The fan-shaped, pear-shaped or paddle-shaped ovaries are located in the 13th segment and form low-yolk eggs that do not form a single egg cord.

Distribution, habitat and way of life

The annelid worms of the family Criodrilidae are common in Eurasia and North Africa. Criodrilus lacuum is found in Germany , Austria , Italy , France , Spain , Portugal , Hungary , the former Yugoslavia , Greece , Latvia , Poland and Russia , as well as in Turkey ( Asia Minor ), Tunisia , Algeria , Syria , Lebanon and in Israel and Palestine native. Biwadrilus bathybates , initially only known from Lake Biwa in Japan, can be found in various inland waters of Japan . Hydrilus ghaniae , however, has been described after finds in Algeria.

The Criodrilidae live in the mud (limikol) of inland waters , in which in addition to fresh water and brackish water is present as a habitat. The mud is often very low in oxygen, which is why they hold their tail sections, which are well supplied with blood, into the open water. Like other crassiclitellates , they eat substrate , digesting the organic components as well as microorganisms in the swallowed mud.

Development cycle

Like all girdle worms , the Criodrilidae are hermaphrodites that exchange their horn- to tubular pseudospermatophores when mating and thus ensure mutual fertilization, because receptacula seminis are not available. With the help of mucus deposits from the clitellum, egg cocoons are formed in which the fertilized eggs develop into small young worms.

Systematics

According to the current view, the Criodrilidae are a family within the order Crassiclitellata which comprises three monotypical genera:

Werner Friedrich Hoffmeister described in 1845 due to a number of discovery in Lake Tegel near the former Prussian city of Berlin at the same genus Criodrilus ( "Aries earthworm", ancient Greek κριός Krios , "Aries" δρίλος, δρῖλος drílos, drîlos "earthworm") and the Species Criodrilus lacuum ("ram earthworm of the lakes", Latin lacus , "lake", lacuum "of the lakes"). In 1884 František Vejdovský finally established the initially monotypical family Criodrilidae.

John Stephenson described annelworms from Lake Biwa, Japan, as Criodrilus bathybates in 1917 . Barrie GM Jamieson granted this species its own genus and named it Biwadrilus bathybates , which he also placed in a separate family Biwadrilidae .

Numerous other species were later described in the genus Criodrilus , including:

  • Criodrilus miyashitai Nagase & Nomura, 1937
  • Criodrilus ochridensis Georgevitch, 1950
  • Criodrilus aidae Righi, 1994
  • Criodrilus venezuelanus Righi & Molina, 1994

While the Criodrilus miyashitai found in Japan is a synonym Biwadrilus bathybates , the other Criodrilus species as well as some species listed under other generic names have been synonymous with Criodrilus lacuum on the basis of a work by RJ Blakemore from 2006 , so that Criodrilus is a monotypical one Genus acts. At the same time Biwadrilus bathybates was placed back in the family Criodrilidae.

literature