Emarginula harmilensis Sturany, 1903

Albano, Paolo G., Bakker, Piet A. J., Janssen, Ronald & Eschner, Anita, 2017, An illustrated catalogue of Rudolf Sturany's type specimens in the Naturhistorisches Museum Wien, Austria (NHMW): Red Sea gastropods, Zoosystematics and Evolution 93 (1), pp. 45-94 : 46-47

Emarginula harmilensis Sturany, 1903 Figure 1

Emarginula harmilensis Sturany, 1903: 235, plate V, figures 12a-b.

Type locality.

Station 143, “nächst der Insel Harmil" [near Harmil Island, Dahlak Archipelago, Eritrea] 17°7'N, 39°55'E, 212 m.

Type material.

Holotype: NHMW 84290, length 6.8 mm.

Original description.

Von der Station 143 (212 m); 1 Exemplar.

Die Schale ist 7 ½ mm lang, 4 mm hoch, 5 ¼ mm breit. Der stark nach rückwärts und etwas nach unten gekehrte Apex fällt fast mit dem Hinterende der Schale zusammen: die absolute Distanz des Wirbelendes zum Schalenende beträgt 2 mm, die relative (bei Projection derselben zur Basis) nur ½ mm. Die schmutzigweiße bis gelbe Grundfarbe des Gehäuses erhält durch radiär angeordnete Fleckchen, Linien und Punkte von brauner bis grünlicher Farbe ein gesprenkeltes Aussehen. Milchweiß gefärbt sind die zahlreichen Hauptradiärrippen, zwischen denen zartere Rippen liegen, die mitunter dunkler erscheinen (zwischen je 2 Hauptrippen liegt eine Nebenrippe). Die erwähnten Rippen werden von vielen zarten Querlinien gekreuzt, an den Kreuzungsstellen der Hauptrippen sind perlenförmige Verdickungen ausgebildet. Der Einschnitt der Schale ist etwas länger als 3 mm: die Ränder derselben sind gerade und innen mit einem verdickten Belage versehen, der sich in Form einer immer stärker werdenden weißen Schwiele bis in die Wirbelgegend fortsetzt. Die Rinne zwischen der Wirbelhöhe und dem blinden Ende des Einschnittes ist stark vertieft, weiß gefärbt und quer gestreift.

Die neue Art ist mit Emarginula bellula A. Ad. von den Philippinen verwandt.

Translation.

From station 143 (212 m); one specimen.

The shell is 7.5 mm long, 4 mm high, 5.25 mm wide. Apex positioned strongly backward and downward almost coinciding with the end of the shell: the absolute distance from the apex to the shell margin is 2 mm, the distance between the apex projection on the base and the posterior margin is only 0.5 mm. The whitish to yellow background shell colour has a spotted appearance because of the radially arranged blotches, lines and dots of brown to greenish colour. The numerous main radial ribs are milky white, whereas the finer ribs in between are darker (between two main ribs there is one finer rib). The ribs are crossed by many delicate transverse lines, the intersections form pearl-shaped tubercles. The slit is slightly longer than 3 mm: its edges are straight showing internally a thickened coating, continuing as white callus in the spire. The groove between the apex and the slit [anal fasciole] is very deep, white and transversely ribbed.

The new species is related to Emarginula bellula A. Adams from the Philippines.

Comments.

[text by D. Geiger] The species is clearly a member of Emarginula given the overall shell outline, the height of the shell as well as the slit with parallel margins. It is not a juvenile Fissurellinae or Diodorinae , because at the size of Sturany’s specimen a hole would have formed. Note that some juvenile Diodora have been described as distinct species, such as Puncturella piccirida Palazzi & Villari, 2001 from the Mediterranean. However it lacks the distinctive internal septum of Puncturella .

Sturany’s Emarginula harmilensis is characterized by a rather uncommon color pattern of tan spiral bands. Those are also found in Emarginula costulata Deshayes, 1863, described from Reunion Island. Herbert (1987: figs 39-40) illustrated the by him designated lectotype, and a more typical, fully-grown specimen (figs 41-42), and discussed previous misidentifications of the species as Emarginula tenuicostata Adams & Sowerby, 1863. The shared characters include overall shape, placement of the spire, length of the slit, color pattern, and number and strength of the ribs. Many species found along the coast of East Africa are also encountered in the Red Sea. Accordingly, Emarginula harmilensis Sturany, 1903 is a junior synonym of Emarginula costulata Deshayes, 1963.

Figures

Figure 1. Emarginula harmilensis Sturany, 1903, Station 143 (Harmil Island, Dahlak Archipelago, Eritrea, Red Sea). A-F, H. Holotype, NHMW 84290: top (A-B), aperture (C), left side (D-E), protoconch (F), microsculpture (H). G. Original figure by Sturany (1903). Scale bars: A-E: 1 mm, F: 0.1 mm, H: 0.5 mm.