The Family Belonolaimidae

Constructed and maintained by Khuong B. Nguyen
University of Florida

Diagnosis: Tylenchoidea. Medium- to large-sized nematodes with tail cylindroid to conoid, more than twice as long as wide but
never elongate filiform.. Stylet slender, occationally very long. Lateral field with 1-6 incisures. Phasmids on posterior half of tail,
never enlarged. Lip region with 4 lips and 2 reduced ones or with six sectors. Females with 2 gonads. Males with peloderan bursa.
    Two subfamilies: Belonolaiminae and Telotylenchinae.

    Diagnosis: Stylet long, around 100 except Sauertylenchus (stylet-37 um), labial disc present. Five genera: Belonolaimus, Carphodorus,
Geocenamus, Morulaimus, and, Sauertylenchus.

Key for the identification of genera:
    1- Lateral field with6 incisures ........................................................................................Geocenamus
       Lateral field with four incisures or less.............................................................................................2
      2- Stylet short, 37 um long .........................................................................................Sauertylenchus
       Stylet  long, 60 um or longer............................................................................................................3
      3- Body more than 2mm long ........................................................................................Belonolaimus
       Body 1.5 mm or less in length ........................................................................................................4
      4- Labial framework weak, perioral disc lemon-shaped, epiptygma present.......................Morulaimus
          Labial framework massive, perioral disc rounded, epiptygma absent ...........................Carphodorus
 

Characters for the identification of genera in the subfamily Belonolaiminae
 

GENUS NAME	Belonolaimus FIG	Carphodorus FIG	Geocenamus FIG	Morulaimus FIG	Sauertylenchus FIG
BODY	2 mm long or more, strongly annulated	about 1mm long coarsely annulated, especially at tail	medium size <1000 um	about 1.5 mm long	about 1.7 mm
HEAD	lip region offset by constriction 4 lobes separated	lip region offset, labial disc present, face view with 6 sectors	lip region offset by constriction, oral disc and tubular stylet guide present	lip region offset by constriction, 4 lobes not separated	lip region offset by constriction, face view with 6 sectors
STYLET	>100 um with basal knobs	97 um or less, slender with knobs	25-130 um long with knobs	100 um or less with basal knobs	about 37 um long, thin with knobs
ESOPHAGUS	overlaps intestine, usually ventrally	overlaps intestine laterally		overlaps intestine dorsally or laterally
LATERAL FIELD	1 incisure	2 incisures	6 incisures	4 incisures	4 incisures
VULVA	near mid-body	near mid-body	near mid-body	near mid-body epiptygma present	near mid-body epiptygma present
GONADS	2	2	2	2	2
PHASMID	small, near mid- tail	on tail	near mid-tail	on tail	on tail
TAIL	cylindrical, 3 ABW, rounded terminus	cylindrical to bluntly conoid 1.5-2 ABW rounded terminus	conoid with blunt or rounded terminus	bluntly conoid 1.5-3 ABW rounded terminus	> 2 ABW conoid with blunt or rounded terminus
BURSA	long, envelops tail	envelops tail	envelops tail	envelops tail	envelops tail

    Stylet short, less than30 um, labial disc absent. Seven genera: Amplimerlinius, Merlinius, Nagelus,
Paratrophurus, Trichotylenchus, Triversus, and Trophurus.

Key for the identification of genera:

    1- Lateral field with 6 incisures ..................................................................................................2
        Lateral field with 2-5 incisures .............................................................................................. 4

    2- Stylet knobs angular ..................................................................................................Nagelus
         Stylet knobs not angular........................................................................................................3

    3-  Body medium to large, tail cylindroid, tail terminus sometimes clavate, hemispherical, annulated
         cuticle on tail terminus, sometimes thickened...................................................Emplimerlinius
         Body medium, tail conoid, never with thickened portion at terminus and not as above..Merlinius

    4- Lateral field with 3 incisures, stylet knobs bi- or trifurcate ...............................Trichotylenchus
       Lateral field 2-5 incisures, stylet knobs not as above................................................................5

    5- Cuticle coarsely annulated, tail tapering to a point, bursa subterminal .........................Triversus
       Not as above .......................................................................................................................6

    6- Gonad one ............................................................................................................Trophurus
       Gonads two..........................................................................................................................7

    7-  Stylet long .....................................................................................................Paratrophurus
          Stylet short ..............................................................................................Tylenchorhynchus
 
 
 

Genus name	Amplimerlinius	Merlinius	Nagelus	Paratrophurus	Trichotylenchus	Triversus	Trophurus	Tylenchorhynchus
BODY	curved when killed by heat	with or without longitudinal grooves	arcuate to spiral when relaxed	medium	small nematode	cuticle coarsely annulated	moderately slender	with or without longitudinal grove, annules coarse
HEAD	fine striation without longitudinal ridges without  disc, strongly cuticularized	continuous or slightly offset; framework sclerotized; disc indistinct	no cephalic framework, lip region asymmetrical	head bullet shaped, not offset	lip region continuous	lip region striated flatterned anteriorly	lip region conical, not annulated, continuous weakly sclerotized	continuous or offset
STYLET	robust,> 20um rounded basal knobs	< 20 um	with angular knobs	well developed, but short <40 um	17-25 um, base bifurcate or trifurcate at end	well developed with knobs	slender <25 um, knobs small but distinct	strong withlarge knobs
LATERAL FIELD	6 incisures	6 incisures	6 incisures	4 incisures	3 incisures	3 incisures	4 incisures	2-5 incisures
VULVA	with epiptygma	with double epiptygma	withdouble epiptygma	stightly post- equatorial	mid-body	mid-body	behind mid- body, vulva sac present	near mid-body
GONADS	2	2	2	2	2	2	1	2
PHASMID	on tail	on tail	on tail	on tail	mid-tail	on tail	near mid-tail	on tail
TAIL	hemispherical, annulated end, cuticle of terminus thickened	variable shape but never thickened at end	bluntly rounded	thick cuticle, annulated or not, memi- sphaerical terminus	tapering, 5 ABW, rounded terminus	tapering to a point	clavate, cuticle thickened, not annulated	variable shape, from bluntly pointed to clavate terminus
BURSA	enveloping tail	enveloping tail	male unknown	enveloping tail	enveloping tail	subterminal	enveloping tail	enveloping tail

Last updated January 2011