Triphora albovittata var. mamillata Verco, 1909

Albano, Paolo G., Bakker, Piet A. J. & Sabelli, Bruno, 2019, Annotated catalogue of the types of Triphoridae (Mollusca, Gastropoda) in the Natural History Museum of the United Kingdom, London, Zoosystematics and Evolution 95 (1), pp. 161-308 : 161

Triphora albovittata var. mamillata Verco, 1909

Figure 109

Triphora albovittata var. mamillata Verco 1909: 285-286, not illustrated.

Type locality.

Gulf St Vincent, South Australia (fide Marshall 1983, by lectotype designation).

Type material.

Lectotype: SAM D.13446 (fide Marshall 1983; not seen, see Remarks) .

Additional material.

NHMUK 1910.3.29.49-51: 3 specimens, Gulf St Vincent , South Australia .

Original description.

Instead of having the elongate four-whorled protoconch of the type, it has a mamillate two-whorled apex. The first whorl is round and smooth, the second has a central carina and subdistant axial bars. Generally the second is swollen and lies somewhat out of the axis of the shell, causing the mamillate form. Rarely the first whorl may be as large as the second. This protoconch seems complete, and not the base of a spiculate protoconch, whose terminal whorls have fallen. The shell varies in shape, being short, broad, and pupaeform, or long, narrow, and elongate-pyramidal.

Dredged in Gulf St. Vincent, 7 perfect and 7 poor; in 90 fathoms off Cape Jaffa, 2 good; in 150 fathoms off Beachport, 2 poor. Taken on the beach MacDonnell Bay, 1; Gulf St. Vincent, 23, in varying condition; Venus Bay, 2, good.

The very different protoconch makes me diffident about calling this a variety, inasmuch as the characters of the protoconch are generally regarded as very certain specific diagnostics; but the shells are otherwise indistinguishable.

Remarks.

Marshall (1983) considered this variety a valid taxon: Obesula mamillata , distinguished by O. albovittata by its paucispiral protoconch. Verco referred to a type series of multiple specimens in his original description. Marshall’s (1983) report of the “holotype” in the SAM should be considered a lectotype designation according to Article 74.6 of the Code ( ICZN 1999).

The specimens in NHMUK represent two strikingly different colour forms: a white form (Fig. 109A, B ) and a form with light brownish shell, white first spiral cord and brown base (Fig. 109C, D ). Marshall (1983) reported that also O. albovittata occurs in two colour forms, similar to the ones illustrated here for O. mamillata and suggested that the only differentiating character between the two species is the protoconch type.

The NHMUK collection register does not indicate that these are “Co-types”, although the specimens were part of Verco’s collection and come from the type locality. Until additional evidence is available, we do not consider these specimens as belonging to the original type series.

Figures

Figure 109. Triphora albovittata var. mamillata Verco, 1909, Gulf St. Vincent, South Australia. A, B NHMUK 1910.3.29.49: front (A), back (B). C, D NHMUK 1910.3.29.50 - 51: front views. Scale bar: 0.5 mm (photo courtesy: Kevin Webb, NHMUK Photographic Unit).