Herviella mietta Er. Marcus & J. B. Burch, 1965

Description

A small aeolid, 7-11 mm in body length. The smooth oral tentacles are about one-third of the body length, and the rhinophores are smooth and slightly shorter than the oral tentacles. The foot is rounded and bilabiate anteriorly. Cerata are slender and fusiform, caducous, and arranged in 5-6 rows on each side. The yellow digestive gland is visible through each ceras; the basal third is brownish, and the apex bears an opaque white cnidosac.
Two colour forms are recognised. The light form has a pale, semi-transparent ground colour, with white granules sprinkled over the back, a black pattern on the head, and black pigment bands across the rhinophores and oral tentacles. The dark form has the back and upper flanks of the foot blackish, while the lower foot and sole are white. Pale haloes occur around the eyes and between the tentacles.

Distribution

Type locality: Eniwetok Atoll, Marshall Islands. The species is broadly distributed across the Indo-West Pacific, with records from the Ryukyu Islands and the Pacific coast of mainland Japan.

Etymology

The specific epithet mietta is the feminine form of the French word "miette" (a crumb or trifle), in reference to the species' small body size. The Japanese vernacular "Mietta-mino-umiushi" was proposed in a report on the opisthobranch fauna of northern Amami-Oshima.

Remarks

The genus Herviella appears to be confined to the western Pacific. Other Japanese congeners include Herviella yatsui and Herviella affinis.

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References

• Herviella mietta n. sp., Marcus Er. & Burch J.B. (1965). Marine euthyneuran Gastropoda from Eniwetok Atoll, Western Pacific. Malacologia, 3(2): 235-262.
• ヘルウィエラ・ミエッタ, 中野理枝. (2004). 本州のウミウシ. ラトルズ.
• Herviella mietta, Terrence Gosliner, Ángel Valdés and David Behrens. (2015). Nudibranch and Sea Slug Identification Indo-Pacific. New World Pubns Inc.
• ミエッタミノウミウシ*(新称), 中野理枝, 朝倉知子, 池田紫, 石川雅教, 今本淳, 岩瀬南美, 西田和記, 堀江諒, 山田久子 & 渡井久美. (2017). 奄美大島北部海域における後鰓類相の調査報告. Kuroshio Biosphere. 13: 1-18 + 6 pls.