8/12/2019 Desert Nematode Primer

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A = algivoreB = bacterivoreF = fungivoreL = liquivoreM= muscivore

P = predatorR = root feeding aka phytoparasitic = yeast ! fungal spores"R# = very rarely $ooparasitic

%ommon groups ! representative e&amples of Mo'ave (esert nemas

cephalobs panagrolaims tylenchs aphelenchs dorylaims

Acrobeles

Acrobeloides

Chiloplacus

Stegelletina

Cervidellus

Cephalobus

Acromoldavicus

Deficephalobus

Halicephalobus

Panagrolaimus

Panagrolaimus Paratylenchus

Tylenchorhynchus

Basiria

Ditylenchus

Anomyctus

Amplimerlinius Aphelenchoides

Seinura

Paravulvus

Tylencholaimus

Aporcelaimellus

Carcharolaimus

All bacterivorous )arro* stoma+ often have labial protrusionsstrong ovoid basal bulb, no prerectum

B,,A-

B,,A-

B,"R#

B-,L-

B,-,A-

R

R

R

F-

R,F-

R,F,M-

R-,F-,M-

P

P-

F A-,F-,M-

Dorylaimellus

A-,F-,M-

Discolaimium

A-,F-,M-

Ecumenicus

A-,F-,M-

Kochinema

P-,A-,F-,M-

P-,A-,F-,M-

.toma shorter ! *ider)ever *ith labial protrusions.trong ovoid basal bulb, no prerectum

.tylet *ith cone/shaft/knobs0eak or strong median bulb, no prerectum

.tylet *ith cone/shaftvery strong median bulb, no prerectum

.tylet *ith only one part ! is clearly hollo* Long or short cylindrical basal bulb+ rectum is often preceded by a

very transparent prerectum

median bulb

median

bulb

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)otes to the previous slide

1 2n addition to the e&amples sho*n, many other groups ! genera *ithin each group can occur in desert soil

1 3he images are not sho*n at the same scale4 Magnifications used for the previous slide are equivalent to oilob'ectives bet*een 56& and 766&

1 3he median and8or basal bulb are s*ollen parts that can occur respectively half*ay or at the end of the muscularpart of the digestive system 9= the pharyn&:

1 2f there is a bulb of this kind then it;s usually located a bit further posteriorly and thus *ould not sho* up in ahigher magnification image photo of the lip region 9unless the nematode is really small, like Basiria:

1 Many dorylaims have a prerectum = structurally different posterior part of the intestine+ it can be shorter or longerand is usually more transparent than the intestine< )o other nematodes have a prerectum

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0hat;s *rong *ith a nematode that doesn;t move,even if you prod it or tap the dish-

1 2f it;s in free *ater 9not 'ust thin surface film: it could be paralysed by lack of o&ygen = it might still recover bypicking it out onto agar that;s already evaporated some *ater and is therefore a little thirsty>

1 2t could be molting = it *ill reactivate *ithin one to several hours+ in the early stages the gut *ill be full of foodreserves about to be used for rebuilding cuticle< 3o*ards the end of a molt the gut clears up and you cansometimes see a ghostly double outline of the ne* head cuticle under production inside the old one

1 2t could have gone quiescent because it doesn;t detect any food source and is saving its last nutrient reserves =

intestine is clear but not decomposed

1 2f the body outline looks irregularly creased or shrunk, or there;s distinct hyphae coming out, then it;s dead< 3heinternals decompose much faster than the cuticle, so a dead nema often looks very messy or completely clearinside