Triforis delicatula Thiele, 1912

Albano, Paolo G. & Bakker, Piet A. J., 2016, Annotated catalogue of the types of Triphoridae (Mollusca, Gastropoda) in the Museum fuer Naturkunde, Berlin, with lectotype designations, Zoosystematics and Evolution 92 (1), pp. 33-78 : 64-66

Taxon classification Animalia Caenogastropoda Triphoridae

Triforis delicatula Thiele, 1912 Figure 31

Triforis delicatula Thiele, 1912: 205-206, plate 12, figure 30.

Type specimens.

Two specimens are present in the ZMB/Moll (no. 63006), but do not correspond to the original description and figure. We refrain at this stage from selecting any lectotypes.

Type locality.

Antarctica, Gauss Station [Davis Sea, 66°02 ’09” S - 89°38 ’05” E, -385 m; fide Engl (2012)].

Original description.

Die einzige Schale von der Gauss-Station (Fig. 30) ist 4,5 mm hoch und 1,25 mm breit, aus 11 Windungen gebildet, die ziemlich schwach gewölbt sind und eine flache Naht zeigen. Sie sind mit schmalen, etwas schrägen Fältchen skulptiert und zeigen etwas unter der Mitte einen Kiel, der besonders auf den unteren Windungen nach oben steiler abfällt, als nach unten; darüber weisen die unteren Windungen noch drei erhabene Spirallinien auf, durch welche die Längsfältchen knotig erscheinen. Unmittelbar über der Naht ist noch eine einfache, nicht knotige Spirallinie sichtbar und an der Unterseite der letzten Windung noch eine ähnliche. Der Spindelfortsatz ist kurz und deutlich gedreht, an dem Exemplar ebenso wie der Unterrand der Mündung etwas beschädigt.

Translation.

The only shell comes from the Gauss Station and is 4.5 mm high and 1.25 mm broad. It has 11 whorls, weakly rounded and shows a flat suture. They are sculptured by thin axial ribs and have a keel on the lower part of the whorl, which is especially prominent on the lower whorls. Moreover, the lower whorls have further three spiral cords, which show tubercles at the intersection with axial ribs. Immediately above the suture a simple smooth cord is visible. Also the base has another smooth cord. The columella is short and clearly curved, but damaged like the lower part of the aperture.

Diagnosis.

Teleoconch up to eight whorls and 6.1 mm, but possibly slightly more, because the largest available specimen has a complete base but not a complete peristome. A strong adapical spiral cord is present since the early teleoconch whorls and further threads later appear. The sculpture on the lower whorls is composed by four spiral cords and prosocline axial ribs which form tubercles at the intersections; a fifth smooth suprasutural cord is also present. The base has a sixth smooth cord. The paucispiral protoconch, composed by 2.5 whorls, suggests lecitotrophic development. The first whorl appears smooth, and the last whorl has axial riblets and a single spiral keel. However, the condition of the specimen with protoconch is very poor, and finer sculpture, if present, cannot be described. Colour ivory, but both specimens are worn and it is difficult to judge which the original colour was.

Remarks.

A single specimen is cited in the original description. However, the lot in the ZMB is composed by two specimens which are different in size (height: 2.9 and 6.1 mm, respectively) than the specimen cited by Thiele (4.5 mm), as already noted by Engl (2012). Also the figure in plate 12 (in Thiele 1912) shows that the available specimens are not the same that Thiele studied: the illustrated specimen has a complete apex and eight whorls, while the smaller specimen in the Museum has a complete protoconch, but just four whorls, while the larger has eight whorls, but no protoconch. Due to these circumstances, these two specimens cannot be considered syntypes, because there is no evidence they were part of the type series that brought to the description of this species.