Metaxia fuscoapicata Thiele, 1930

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 : 54-57

Taxon classification Animalia Caenogastropoda Triphoridae

Metaxia fuscoapicata Thiele, 1930 Figure 23

Metaxia fuscoapicata Thiele, 1930: 575, plate IV, figure 26.

Type specimens.

Holotype: ZMB/Moll no. 67481, fixed by monotypy.

Type locality.

"Station 10 (Sharks Bay)" [Western Australia].

Original description.

Eine wahrscheinlich junge Schale von Station 10 (Sharks Bay) ist durch ihre braune, aus 4 kaum zunehmenden, etwas rauhen Windungen bestehende Embryonalschale ausgezeichnet, von der sich die folgenden farblosen Windungen scharf absetzen; diese, von denen 5 vorhanden sind, haben 4 starke Spiralreifen und einige breite, wellen förmige Rippenfalten, sie sind deutlich gewölbt und in der Mitte etwas kantig; Spindelfortsatz kurz, untere Bucht der Mündung breit. Höhe 2,4 mm, Durchmesser 0,65 mm.

Translation.

A probably young shell from Station 10 (Shark Bay) is characterized by an embryonal shell composed of almost 4 brown whorls. The teleoconch whorls are without colour and start after the larval shell abruptly. The teleoconch is composed of 5 clearly convex whorls with an angulated profile. The whorls have 4 strong spiral cords and some broad, wave-like, axial ribs. The columella is short, the siphonal canal broad. Height 2.4 mm, diameter 0.65 mm.

Diagnosis.

Shell dextrally coiled. Holotype 2.4 mm high, teleoconch composed of five whorls; however, this specimen is likely a subadult. Whorls have eight orthocline axial ribs and three main flat spiral cords; the last two whorls have a sub- and supra-sutural cord. The whorl profile is angulated due to the prominence of the cord in the middle of the whorl. Protoconch multispiral, composed of at least four whorls (but holotype apex is damaged), with zigzag threads on the first and second whorl, followed by axial riblets. Protoconch brown, teleoconch white with occasional tiny faint brown patches on spiral cords between axial ribs.

Remarks.

Although the examined type specimen is likely a sub-adult, the specimen identified as Metaxia fuscoapicata illustrated by Marshall (1983, figure 9 A-C) may not actually be this species: the holotype has much more convex teleoconch whorls (although juvenile), a lower number of axial ribs, a less angulated protoconch periphery and the zig-zag threads still clearly visible on the second protoconch whorl. More adult and complete specimens from the type locality would be needed to better define this taxon and discriminate it from closely related ones.