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Doto koenneckeri Lemche, 1976

Author & date of last revision: Ian Smith on 30 July 2012

Description

Body (excluding appendages) [image7]
Up to 9mm long. Translucent whitish epidermis, but overall brown appearance because of large areas of dark brown surface pigment and orange-brown viscera showing through unpigmented parts. Conspicuous pale unpigmented subdorsal line on either side linking bases of rhinophore sheath and cerata.
Cerata
Single row of up to five each side of body leaving dorsum fully exposed [7]. No cnidosacs at tips. Translucent whitish, revealing orange-brown internal digestive gland which extends two thirds the way up. Each ceras has only 2 or 3 concentric rings of elongated, internally white, tubercles and a very long terminal tubercle [3]. Cerata have many dark brown rounded, but rarely circular, pigment marks and streaks on the surface.
Rhinophores [1]
Smooth, translucent white with some white surface pigment spots. Arise from a translucent white narrow basal sheath with dilated smooth rim.
Head
No oral tentacles, but front margin expanded laterally into large lobes [8].
Foot
Sole brownish white [8]. No propodial expansion (but large oral lobes).

Key identification features

  • Dark brown body with wide pale unpigmented subdorsal line on either side connecting the base of the rhinophore sheath and cerata. [1].
  • Rounded, but rarely circular, brown marks and streaks on cerata [3].
  • Each ceras has only 2 or 3 concentric rings of elongate tubercles

Similar species

About seven other British and Irish species of Doto have brown markings, but all have 4 or more concentric rings of tubercles on each ceras, and none has the distinctive pale unpigmented subdorsal lines of D. koenneckeri.

Ecology and behaviour

Sublittoral and LWS where its prey, Aglaophenia pluma (EML), occurs on rocks and on Halidrys siliquosa [6], which often forms a belt below the Laminaria zone. The pale hydroid, and white D. koenneckeri spawn on it, show clearly when the alga is in water, and probably indicate adults near by. Simultaneous hermaphrodite. Convoluted white or pinkish ribbon of spawn [4] draped round A. pluma in May, August and possibly other summer months. Shelled veligers drift as plankton before settling on the sea floor and transforming into adults.

Distribution and status

Norway to Spain (GBIF map). Widespread and not uncommon when Aglaophenia pluma [5] growing on Halidrys siliquosa [6] is searched, but few records in Britain and Ireland.
 

References and links

Thompson, T.E. & Brown, G.H. 1984. Biology of opisthobranch molluscs 2. London, Ray Society.
 
Current taxonomy; World Register of Marine Species (WoRMS)
Irish distribution map and prey organisms
Picton, B.E. & Morrow, C.C., 2010. Encyclopedia of Marine Life of Britain and Ireland  (EML)

 

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Doto koenneckeri. L. 9mm. Unpigmented pale subdorsal lines. Single row of five cerata each side of body leaving dorsum fully exposed. No cnidosacs. LWS, Menai Strait, Wales. August 2010.
Image © I.F. Smith
Ventral view of D.koenneckeri (centre) floating over Aglaophenia pluma. Length 9mm. Spawn at base of image. LWS, Menai Strait, Wales. August 2010.
Image ©

I.F. Smith

Additional images

  • Doto koenneckeri. L. 9mm. Unpigmented pale subdorsal lines. Smooth translucent rhinophores in narrow sheaths with dilated rim. LWS, Menai Strait, Wales. August 2010.
  • Ventral view of Doto koenneckeri floating over Aglaophenia pluma on Halidrys siliqua. Head with large oral lobes protrudes beyond foot. Length 9mm. LWS, Menai Strait, Wales. August 2010.
  • Cerata of Doto koenneckeri with rounded, but not circular, brown marks. Length 9mm. On Aglaophenia pluma on Halidrys siliqua, LWS, Menai Strait, Wales. August 2010.
  • Spawn ribbon of Doto koenneckeri. Length 9mm. On Aglaophenia pluma on Halidrys siliqua, LWS, Menai Strait, Wales. August 2010. Adults were near by.
  • Halidrys siliqua and sectioned air vesicle.

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Recorded UK distribution