Type: Valdiviella oligarthra Steuer,1904. Total: 7 spp.
For Tanaka (1957 b, p.205) the genus Valdiviella was created by Steuer (1904) to accomodate a new species (V. oligarthra which is closely related to Euchaeta and also to some genera of Aetideidae.
According to Steuer, the genus has the mandible similar in structure to those of Gaetanus and Chiridius; Mx1 as in Undeuchaeta; Mx2 as in Aetideus, thus the genus Valdiviella is regarded as a member of the family Aetideidae, whereas Sars (1925, p.98) doubts of this justification. A. Scott states that ''the genus is closely related to Euchaeta, but easily recognised by its bifurcate rostrum; the incomplete segmentation of the exopodites of P1 and P2, and indistinctly 3-segmented endopodites of P3 and P4''.
- The genus has general appearance as in Euchaeta; head and 1st thoracic segment fused, 4th and 5th thoracic segments fused; posterior margin of last thoracic segment rounded; abdomen 4-segmented; appendicular seta short; endopod of A2 about as long as exopod; endopod of Md about as long as exopod;
- Mx1 differs from that of Euchaeta : setae on endopod and 2nd basal segment much reduced, endopod with only 3 setae, 2nd basal with 3 setae whereas that of Euchaeta with 3+3+3 setae on endopod, and 5 on 2nd basal segment;
- Mx2 resembles that of Aetideidae, setae on 5th lobe strong; Mxp resembles that of Undeuchaeta and Euchaeta, but row of spinules on anterior margin of 2nd basal segment are situated on the proximal half, wherea, it is on the distal half in Euchaeta, and thet are feeble.
- P1 as in Euchirella : 1st and 2nd exopodal segments fused; endopod of P2 1-segmented, that of P3 2-segmented; P4 exopod and endopod 3-segmented each; P5 absent in female; male P5 resemble those of Chirundina. The genus has a closer relationship to Aetideidae : rostrum resembles that of Aetideopsis or Undinopsis in its bifurcate shape;
Mx1 has the reduced number of setae on endopod and on 2nd basal segment.
- Mx2 as those of Aetideus in having 1 strong seta on 5h lobe (= endite).
- P1 similar to those of Euchirella.
- P2 as in Euchirella or Undeuchaeta.
- The genus has resemblance to Euchaeta: general appearance, structure of A1, Md and Mxp. Thus Valdiviella has the generic characters common both Aetideidae and Euchaetidae; it is intermediate form between Undeuchaeta and Euchaeta. For the author it seems reasonable, as Steuer stated, to accomodate it in the family Aetideidae.
For Vervoort (1957, p.87) the genus, in many respects, takes an intermediate position between the Aetideidae and the Euchaetidae. It approaches the Aetideidae in the structure of the rostrum, swimming legs, in the case of males, the structure of P5. The structure of Mxp shows unmistakable affinities with the Euchaetidae.
The belonging of this genus to this family is discussed by Heptner (1971) and by Zvereva (1975).

Definition after Bradford & Jillett (1980, p.83) Female:
- General appearance as in Euchaeta.
- Rostrum bifurcate.
- Head and pediger segment 1 fused, 4th and 5th pediger segments fused..
- Posterolateral corners of last thoracic segment rounded.
- A1 23-segmented (as in Euchaeta).
- A2 exopod and endopod equal in length.
- Mx1 with reduced setattion on inner lobe 1 (arthrite), endopod and basipodal segment 2 (11, 3, 3 setae respectively); posterior surface of inner lobe 1 with only 1 seta.
- Mx2 as in Aetideus, seta on lobe 5 strong.
- Mxp as in Undeuchaeta and Euchaeta, but row of spinules on anterior margin of basipodal segment 2 situated proximally not distally as in Euchaeta
- Swimming legs with some degree of fusion between proximal segments.
- P5 absent.