Species Account

Leptaxinus incrassatus (Jeffreys, 1876)

Thyasiroidea : Thyasiridae

Tebble name: n/a
Smith & Heppell name: Thyasira incrassata (Jeffreys, 1876)

Notes on Nomenclature

Leptaxinus incrassatus (Jeffreys, 1876) and Thyasira incrassata (Jeffreys, 1876) both appear as accepted taxa in WoRMS, although they are synonymous. CLEMAM use Thyasira incrassata (Jeffreys, 1876).

The generic and subgeneric divisions of the Thysiridae are more distinct than suggested by CLEMAM and WoRMS. However, we recognise that many species remain problematic when assigning them to subgenera.

To size: To 2mm. Shell Structure: Robust, thickened. Equivalve: Equivalve. Equilateral: Slightly inequilateral, beaks a little behind midline. Tumidity: Inflated. Outline: Suboval, height a little greater than length, somewhat oblique extended anterio-ventrally. Posterior dorsal slope steep, slightly angles with rounded posterior; ventral and anterior a continuous broad curve; anterior dorsal margin short, almost straight. Contour: Umbos prominent; submarginal sulcus very deep; lunule distinct demarcated by an indented groove.

Sculpture: Of fine concentric lines most prominent at margins. Margin: Inner margin smooth. Ligament: Ligament deeply inset, short. Hinge: Hinge plate very thick; RV with rounded elongate swelling ventral and anterior to beak with corresponding depression in LV; Anterior and posterior lateral thickenings forming pseudo-lateral teeth. Pallial Musculature: Obscure. Periostracum: Transparent. Colour: Straw-coloured. Additional Characters: 1 demibranch.

Distribution & Ecology

Found to the west of the UK in depths of 200-4000m from Rosemary Bank and south to Bay of Biscay.

Depth Range
Continental Margin Zone (200 - 500m)
Bathyal (500 - 2000m)
Abyssal Rise (2000 - 4000m)

Additional Information & Related Species


Listed are literature citing Leptaxinus incrassatus (Jeffreys, 1876). Reference containing the species Type Description is highlighted.

Jeffreys J G 1876. New and peculiar Mollusca of the Kellia, Cyprina and Corbula families, procured in the Valorous expedition. Annals and magazine of natural History. (4) 18: 490-499.


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Record last modified: 17/05/2016