Ascolaimus elongatus

The nematode Ascolaimus elongatus (Bütschli, 1874) Ditlevsen, 1919 belongs to the marine nematodes (family: Axonolaimidae). It can be found in estuary and intertidal sand and mud in Europe and North-America. For a long time A. elongatus was the only known species within Ascolaimus, till 2010 when A. australis was described from Australia. Morphologically A. elongatus can be recognized by the presence of six small labial setae, four long cephalic setae and 4 rows of medium sized somatic setae within the pharynx region. It also has a relatively large amphid forming a rounded loop and a weakly sclerotized buccal cavity. The short nearly cylindrical tail includes three caudal glands typically with swollen ducts towards the tail tip. The male spiculus has distinct hooked distal ends and spade-shaped proximal cephalisation, the gubernaculum shows a relatively large dorso-caudal apophysis.   

Ascolaimus elongatus: female anterior body
Ascolaimus elongatus: female anterior body
Ascolaimus elongatus: female mid-body
Ascolaimus elongatus: female mid-body
Ascolaimus elongatus: female posterior body
Ascolaimus elongatus: female posterior body
Ascolaimus elongatus: head region with cephalic setae and amphid
Ascolaimus elongatus: head region with cephalic setae and amphid
Ascolaimus elongatus: head reagion with amphid in detail
Ascolaimus elongatus: head reagion with amphid in detail
Ascolaimus elongatus: head region with weakly sclerotized buccal cavity
Ascolaimus elongatus: head region with weakly sclerotized buccal cavity
Ascolaimus elongatus: head regaion with weakly sclerotized buccal cavity
Ascolaimus elongatus: head regaion with weakly sclerotized buccal cavity

Ascolaimus elongatus: head region with cephalic setae, amphid and somatic setae
Ascolaimus elongatus: head region with cephalic setae, amphid and somatic setae
Ascolaimus elongatus: pharynx-intestine region
Ascolaimus elongatus: pharynx-intestine region
Ascolaimus elongatus: anale opening and posterior part of three rectal glands
Ascolaimus elongatus: anale opening and posterior part of three rectal glands
Ascolaimus elongatus: spiculus and gubernaculum (focus on gubernaculum)
Ascolaimus elongatus: spiculus and gubernaculum (focus on gubernaculum)
Ascolaimus elongatus: spiculus and gubernaculum (focus on spiculus tip)
Ascolaimus elongatus: spiculus and gubernaculum (focus on spiculus tip)
Ascolaimus elongatus: spiculus and gubernaculum (focus on spade-shaped proximal cephalisation)
Ascolaimus elongatus: spiculus and gubernaculum (focus on spade-shaped proximal cephalisation)

Ascolaimus elongatus: vulva
Ascolaimus elongatus: vulva
Ascolaimus elongatus: posterior tail part with spinneret
Ascolaimus elongatus: posterior tail part with spinneret

(Click on the pictures for an enlargement, ©Wageningen University & Research, Laboratory of Nematology/Pictures: Hanny van Megen)