Family EUHERDMANIIDAE

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Introduction

In the family Euherdmaniidae Ritter, 1904 (as in the Placentelidae, Protopolyclinidae, Ritterellidae and Pseudodistomidae), atrial and branchial apertures open separately to the exterior by 6-lobed apertures, zooids are either separate (usually joined by basal stolons) or embedded in common test, and gonads are in a posterior abdomen. The Euherdmaniidae are distinguished by certain characters that suggest a close relationship with Pycnoclavellidae, namely, the stomach at the posterior end of a long narrow gut loop; embryos fertilised at the base of the oviduct and incubated as they move up the oviduct to the atrial cavity; and larval adhesive organs in the form of inverted tubes that evert for attachment to the substrate. The lobed apertures, (usually) a posterior abdomen containing the gonads, and replication by strobilation of the abdomen (rather than by generation of clones in the vascular stolon) distinguish the family from Pycnoclavellidae. Longitudinal muscle bands from the thorax converge to a band along each side of the abdomen and the posterior abdomen as in most aplousobranch families.

Euherdmaniinae was originally established as a subfamily in the Polyclinidae for aplousobranch genera with separately opening, 6-lobed atrial apertures. Kott (1992) elevated it to family status, basing the amended definition on the type species of Euherdmania, Euherdmania claviformis (Ritter, 1903). Euherdmania is the only known genus in the family. It contains about 10 known species worldwide, three occurring in Australian waters. They are seldom recorded, and the known geographic ranges of most species are limited.

General References

Kott, P. 1992. The Australian Ascidiacea Pt 3, Aplousobranchia (2). Memoirs of the Queensland Museum 32(2): 377-620

Ritter, W.E. 1903. The structure and affinities of Herdmania claviformis, the type of a new genus and family of ascidians from the coast of California. pp. 237–261, pls xviii, xix. in, Mark Anniversary Volume. New York : Henry Holt & Co.

Ritter, W.E. 1904. Euherdmania vs. Herdmania preoccupied. Zoologischer Anzeiger 27: 650-651

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