Diplolaimella

  

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Rev: 03/31/2025

  Classification Biology and Ecology
Morphology and Anatomy Life Cycle
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Distribution Management
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Classification:

Chromadorea
  Chromadoria
   Monhysterida
Monhysterina
Monhysteroidea
            Monhysteridae
Diplolaimellinae
       Diplolaimella Allgen, 1929

Type species of the genus: Diplolaimella monhysteroides (species inquirenda)

    Synonyms:
     

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Morphology and Anatomy:

Members of the subfamily Diplolaimellinae of the Monhysteridae are characterized by a double buccal cavity at some point during their juvenile or adult stages, while those in the other subfamily, the Monhysterinae, have a single tapered buccal cavity.

Absence of a copulatory bursa in males is an important character in distinguishing Diplolaimella.  Diplolaimella clearly differs from Monhystrium, Tripylium, and Diplolaimelloides (in the same subfamily) by the absence of a male copulatory bursa and the presence of an apophysis on the gubernaculum (Shimada et al., 2022).

Several species of Dorylaimella and/or Dorylaimoides are considered species inquirendae because a male has not beenj described and the presence or absence of a bursa or apophysis on the gubernaculum is unknown (Shimada et al., 2022)..

The following genus description adapted from that of D. ariakensis (Shimada et al., 2022).
  • Buccal cavity 1.0-1.2 cephalic body diam. (cbd) long, divided into two chambers:
  • Anterior buccal chamber 0.6-0.7 cbd. long, consisting of cheilostome and anterior part of pharyngostome, surrounded by body cuticle at the cheilostome level, funnel-shaped and sclerotized at pharyngostome level,
  • the posterior chamber corresponding to posterior part of pharyngostome, is spherical in shape, less sclerotized than the anterior chamber, and without denticles.
  • Amphidial aperture circular,
  • Ocelli (eye spots) paired, not present in all species, consisting of translucent lens and red-violet pigment spot,, located dorsolaterally and conspicuous in living nematodes.
  • Pharynx muscular, gradually widened to posteriorly but without terminal bulb. Cardia distinct
  •  Pore of secretory-excretory system at about 5.5 cbd from anterior body.
  • Tail elongated, conical, strongly tapering in anterior quarter and then gradually tapering toward tip, about 12.5 cloacal body diam. long or 25-31% of body length.
  • Spinneret present at tail tip

Females:

  •  Monodelphic, prodelphic, ovary outstretched,
  • Oviduct narrow and surrounded by wall of large cells.
  • Uterus single, without post-vulval vaginal sac or gland-like structure.
  •  Vulva located at 43-46% of body length from anterior end, surrounded by thickened body cuticle.
  • Vagina straight and strongly sclerotized, with well-developed constrictor muscle.

Ref: Shimada et al., 2022
Anterior region of Diplolaimella and other members of the subfamily Diplolaimellinae showing the buccal cavity with two chambers and the circular amphid.
Adapted from Shimada et al., 2022

 

Males:  

  • Monorchic; testis outstretched
  • Seminal vesicle containing globular sperm.
  • Spicules 1.4-1.8 cloacal body diam.(cbd) or  long, paired, slender and arcuate,
  • Gubernaculum tubular, with a dorsocaudal apophysis which is longer than the corpus of the gubernaculum and 0.5-0.7 cbd long.,
  • Bursa absent.
  • Plate-like precloacal ventromedian supplement present on elevation of body cuticle,
  • Postcloacal papillae absent.
  • One pair of precloacal and six pairs of postcloacal body pores present 

 

Body size range for the species of this genus in the database - Click:
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Distribution:

Free-living marine nematodes; generally in bottom sediments.

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Feeding:

Bacterial and probably epistrate feeders. Often reported from sediment in muddy tidal flats.

 
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Biology and Ecology:

Life Cycle:

For Ecophysiological Parameters for this genus, click 
 
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Ecosystem Functions and Services:

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Management:

 
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References:

Allgen, C. 1929.. Sudschwedische marine Nematoden. Goteborgs kungliga vetenskaps-och vitterhets-samhalles Handlingar. Femte Foljden Ser B 1(2): 1-40.

Kito, K., Aryuthaka, C. 1998.  Free-living marine nematodes of shrimp culture ponds in Thailand. I. New species of the genera Diplolaimella and Thalassomonhystera (Monhysteridae) and Theristus (Xyalidae). Hydrobioloia 379:123-133

Pastor de Ward, C.T. and Lo Russo, V. 2009.. Distribution of Diplolaimella and Diplolaimelloides species from Patagonian lagoons and coastal waters (Nematoda: Monhysteridae), Chubut and Santa Cruz provinces (Argentina). Journal of the Marine Biological Association of the United Kingdom 89:711-718. DOI: 10.1017/S0025315409000198

Shimada, D., Komiya, T., Yoshiga, T. 2022. A new species of free-living marine nematode, Diplolaimella ariakensis n. sp. (Nematoda: Monhysteridae) from the Ariake Sea, Japan. Nematology 24:321-331.

Timm, R.W. 1967.. Some observations on the nematode genera Diplolaimella and Diplolaimelloides. Proceedings of the Pakistan Academy of Sciences 3:114-125

 

 

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Copyright © 1999 by Howard Ferris.
Revised: March 31, 2025.