The Small World of Freshwater Gastrotrichs
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Heterolepidoderma majus

  • Order: CHAETONOTIDA Remane, 1925
    • Suborder: PAUCITUBULATINA d'Hondt, 1971
      • Family: CHAETONOTIDAE Gosse, 1864
        • Subfamily: CHAETONOTINAE Kisielewski, 1991
          • Genus: Heterolepidoderma Remane, 1927
            • Species: majus Remane, 1927
(after (Remane, 1927))
Length ( bottle ):
130 µm - 200 µm

29 µm - 30 µm

Width of the head ( threelobed ):
21 µm - 23 µm

Width of the neck:
18 µm - 19 µm

Length of the furca:
14 µm - 20 µm

Adhessive tubes:
50% of furca

Pharyx ( cylindrical, terminal swollen ):
35 µm - 51 µm

Diameter of the mouth ( around ):
7 µm

Dorsal scales:
25 rows of 40-80 elongated narrow keel scales each (3 x4 µm, maximum 7 µm)

Ventral scales:
6-11 rows with 18-30 small keel scales each (1.5 - 3 µm)

very common, on mud

Stomach ring, sometimes stands still


Heterolepidoderma majus is a very widespread, slender and elegant belly-hardy.

H. majus: dorsal scaling (©️ Ole Riemann)

One of the animals observed was in its post-parthenogenetic (hermaphroditic) phase and showed a sperm bundle in addition to the conspicuous bipartite X-organ at the posterior end:

H. majus: x-organ (xO) and sperm bundle (Sp)(©️ Ole Riemann)

The scaling at the base of the toes is typical for the species. The sensory hairs arise from special scales:

H. majus: Scaling of the base of the toes (©️ Ole Riemann)

The ventral intermediate field is occupied by small, elongate keel scales and bears two terminal keel plates:

H. majus: Scaling of the ventral interfield

Another feature that makes the species distinctive is the demarcated “stomach ring” on the foregut:

H. majus: Intestine with “stomach ring”


(Remane, 1927)