Questa (genus)

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Questa
Systematics
Over trunk : Lophotrochozoa (Lophotrochozoa)
Trunk : Annelids (Annelida)
Class : Polychaete (Polychaeta)
Order : Scolecida
Family : Orbiniidae
Genre : Questa
Scientific name
Questa
Hartman , 1966

Questa is the name of a genus of Vielborstern (Polychaeta), which are found in oceans worldwide as detritus from the coastal strip to the deep sea. The Novaquesta with the only species Novaquesta trifurcata , which wastemporarily run as a separate genus,was synonymous with Questa in 1998. The genus has been part of the Orbiniidae family since 2000, so the family name Questidae is no longer used.

features

The multi-bristle of the genus Questa have an elongated and slender, mostly reddish-orange-colored body with a blunt head without body appendages such as antennae or palps, which is reminiscent of little- bristle and is up to 1 cm long in adult animals and has up to 60 bristle-bearing segments .

The prostomium is approximately conical to the front broadly rounded and has neither body appendages such as antennae or palps nor eyes. Slit-shaped nuchal organs sit on the posterolateral edge of the prostomium . Aside from these, the only known sense organ is a series of lateral organs that sit on each segment between the Notopodium and Neuropodium. The peristomium and the first, bristle-free segment are more or less distinct ringlets. The following trunk segments are often curled in a secondary manner, especially in the middle section of the body. The reduced parapodia have two short, papillary-shaped bristle lobes, on each of which the bristles sit in a bundle, and no aciculae. All Questa species have sawn capillary-shaped bristles and hook-shaped bristles with a subdental ligament, but Questa trifurcata also has three-forked bristles and triple hooks on the anterior parapodia. On the back of the middle and / or rear segments of most species such as Questa ersei there are simple ciliate gills , which are missing in some species such as Questa trifurcata . The pygidium is bilobed or rounded and in most species carries paired cirrus both dorsally and ventrally, but not in Questa trifurcata .

The segment partitions are well developed except in the gonad-bearing segments. In Questa trifurcata and Questa ersei , the ventrally located mouth leads into a small buccal cavity, which in turn merges into a narrow, jawless and toothless, ventrally located pharynx . This is clearly separated from the eyelashed esophagus , which in turn merges into a midgut narrowed between the segments, on the front section of which a pair of ventrolateral blind sacs with varying positions depending on the type extend. The back vessel of the closed blood vessel system branches in the 1st segment and forms a loop at the front that supplies the brain, and vessels leading around the pharynx, which unite in the 2nd and 3rd segment to form a centrally located abdominal vessel. This is connected to the dorsal vessel via side vessels along the furrows of the intestine between the segments. The nephridia lead to the outside via openings slightly below the notopodia. The brain is trapezoidal in shape and is located entirely within the prostomium.

distribution and habitat

Annular worms of the genus Questa are widespread and have been found on the Pacific and Atlantic coasts of North America , the Gulf of Mexico , the Caribbean Sea , the Galapagos Islands , the Philippines and the Mediterranean Sea . They occur in shallow waters as well as in the deep sea , but rarely in high population density. Questa caudicirra may appear as a cosmopolitan worldwide. The animals live in fine and medium-coarse sand, which is rich in organic matter, as well as in carbonate sediments such as coral and mussel shill. They move between the sediment grains with the help of their long and flexible bristles.

The animals swallow diatoms , plant material and grains of sand with organic matter adhering to them and bacteria growing on them by invading their tongue-like buccal organ .

Development cycle

The multi-bristle of the genus Questa are separate sexes. The ovaries at the anterior partitions of the 12th and 13th segments form yolk-rich eggs up to 200 μm in size, which are released through 2 or 3 ventrolateral openings on the 12th to 14th segment. The females have one ( Questa ersei ) or two ( Questa trifurcata ) unpaired receptacula seminis in the 5th to 7th segment, those on the back between the 5th and 6th segment ( Questa ersei ) or two unilateral, left-hand pores on these segments ( Questa trifurcata ) open outwards. A glandular, papilla-rich, if not easily recognizable belt, which resembles the clitellum of few bristles, extends from the 9th to the 11th segment. The males form their sperm in inconspicuous scrotums in the 11th and 12th segments, which lead via muscular sperm stores and narrow sperm conductors into large, glandular copulation humps on the back of the 13th to 15th segment. The annelids of the genus Questa mate back to back so that the sperm are transferred from the copulation humps on the male's back into the openings of the receptacula seminis on the female's back. After copulation, the female secretes a gelatinous belt in which she lays mature eggs and fertilizes them with the sperm of the sex partner from the receptacula seminis. The larvae of Questa trifurcata develop in oval cocoons that are laid in autumn, and after 4 to 6 weeks, worms with 7 bristle-bearing segments hatch.

Genera

Simultaneously with the description of the type species Questa caudicirra , Olga Hartman established the genus Questa and the family Questidae in 1966 , in which the genus Novaquesta described by Hobson in 1970 with the only species Novaquesta trifurcata was placed. In 1998, however, Giere and Erséus synonymized Novaquesta with Questa in their revision .

The following 10 species belong to the genus Questa :

literature

  • Olga Hartman (1966): Quantitive survey of the benthos of San Pedro Basin, southern California. Part II. Final results and conclusions. Allan Hancock Pacific Expeditions, 19 (2), pp. 187-455, here p. 197. Questidae, new family, Questa , new genus, Questa caudicirra , new species.
  • Olav Giere, Christer Erséus (1998): A systematic account of the Questidae (Annelida, Polychaeta), with description of new taxa. Zoologica Scripta 27 (4), pp. 345-360.
  • Stanley J. Edmonds: Fauna of Australia, Volume 4A. Polychaetes & Allies. The Southern Synthesis 4. Commonwealth of Australia, 2000. Class Polychaeta. Pp. 110-113, Family Questidae.

Individual evidence

  1. ↑ Questa Hartman, 1966. WoRMS , 2018. Retrieved December 6, 2018.