Corresponding author: André R. S. Garraffoni (
Academic editor: M.A. Todaro
The semi-pelagic gastrotrich species
Minowa AK, Garraffoni ARS (2018) Redescription of the dasydytid gastrotrich
While most gastrotrichs are epibenthic, periphytic, or interstitial, some species belonging to the family
While preparing a forthcoming study incorporating phylogenetic analyses of all valid
Herein we redescribe
The observed specimen has a compact, bowling pin-shaped body, measuring 88 μm in total body length, 184 μm with spines included. Conical head with convex sides (24 μm wide), pentalobate, dorsally with a middle furrow (Figure
Cephalic spines or rear spines not observed. On the anterior half of the trunk four paired groups of 2-2-2-1 curved simple spines (ta1-2, tb1-2, tc1-2, td) respectively, inserted directly on the cuticle without scales (Figs
Trunk locomotory ciliation divided into 2-paired ventral tufts at 15U and 93U on the ventral side of at the neck and posterior trunk, respectively (Figure
Mouth ring is terminal (3 μm in diameter). Pharynx (33 μm in length) increases in width uniformly from 9 μm anteriorly to 11 μm at the posterior end) (Figure
Light micrographs (
Usually, the trunk width is given as the maximum trunk widthwhich is at the midgut level. In this case, the type specimen
Differences in spines length between the original description and the present one (Table
Additionally, the original description mentions a pair of caudal bristles (Figure
As previously mentioned, the description of some morphological characters of
Light micrographs (
Morphometric features of
Feature type | Measure (μm) |
---|---|
Total body length, spines excluded | 88 |
Total body length, spines included | 184 |
Maximum head width) (U17) | 24 |
Minimum neck width (µm) (U30) | 17 |
Maximum trunk width (µm) (U65) | 42 |
Trunk length (µm) | 60 |
Pharynx length (µm) | 33 |
Anterior pharynx width (µm) | 9 |
Posterior pharynx width (µm) | 11 |
Diameter of mouth ring (µm) | 3 |
Kephalion length (µm) | 9 |
Kephalion width (µm) | 13 |
Hypostomion length (µm) | 5 |
Hypostomion width (µm) | 8 |
Spine ta1-2 length (µm) | 100, 90 |
Spine tb1-2 length (µm) | 75, 90 |
Spine tc1-2 length (µm) | 82, 80 |
Spine td length (µm) | 140 |
Ventral spine ta1-2 insertion | U32, U35 |
Ventral spine tb1-2 insertion | U38, U40 |
Ventral spine tc1-2 insertion | U46, U50 |
Ventral spine td insertion (U) | U60 |
Cephalic ciliary tufts insertion (U) | U1, U4, U8 |
Ventral trunk ciliary tufts insertion (U) | U15, U93 |
1 | Seven pairs of spines with ventral insertion besides td (saltatorial spines) |
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– | Six or fewer pairs of spines with ventral insertion besides td (saltatorial spines) |
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2 | Dorsal trunk totally or partially covered with rhombic scales arranged sparsely or aggregate |
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– | Dorsal trunk without scales |
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3 | Dorsal scales arranged sparsely; dorsal trunk covered with rhombic scales with a short median keel or smooth; ventral trunk covered with small smooth scales |
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– | Dorsal scales aggregate; median and rear dorsal trunk covered with smooth, rhombic scales; ventral trunk without scales |
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4 | Anterior spines (ta) cross each other above dorsal trunk |
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– | Anterior spines (ta) do not cross each other above dorsal portion of the trunk |
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5 | Ventral ciliature consisting of 2 tufts; 3 pairs of spines arrive to the dorsum while 3 other spines remain ventral besides td group |
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– | Ventral ciliature consisting of 2 longitudinal bands; all 5 pairs of spines arrive to the dorsum; only td group remain on venter |
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We are grateful to Fundação Amparo à Pesquisa do Estado de São Paulo − FAPESP (grant numbers: 2014/23856-0; 2017/20312-8) for financial support; Freya Goetz (Smithsonian Institution, National Museum of Natural History, Department of Invertebrate Zoology) for assistance with micrographs and videos of the type specimen; to Brett Christopher Gonzalez for editing the English text; an anonymous referee for offering suggestions that greatly improved the paper.