Turridrupa erythraea (Weinkauff, 1875)

(Figs. 20 A–G, 22 E–F)

Pleurotoma erythraea Weinkauff, 1875: Red Sea: Ethiopia: Massaua (leg. JICKELI), 22, pl. 4 f. 10.

Xenuroturris cingulifera erythraea; Powell 1964: 323, pl. 252 f. 1; Sharabati 1984: pl. 33 f. 17.

Lophiotoma erythraea Verbinnen & Dirkx, 2004: 18, fig. 26.

Turridrupa sp; Rusmore-Villaume 2008: 134, figs.

Turridrupa erytharaea; Janssen, Kantor & Stahlschmidt 2015: 99–101, figs. 1–9.

Type material

Lectotype: 18.4 mm (SMF 346012, Figs. 20 A–B)

Paralectotype: 16.7 mm (SMF 346013) .

Sequenced material

SAUDI ARABIA: Farasan Islands, 15 m, coll by P. Stahlschmidt (MNHN-IM-2013-57409).

Material examined

EGYPT: N of Dahab, Abu Galum: 5–35 m, 2 spms (SMF 346014; PS- 441)—Hurghada, Abu Ramada Island: on rubble, 15–30 m, 1 spm (PS- 440)—Brothers Island: 10–35 m, 1 spm (SMF 346016; radula voucher, Figs. 20 C–E)—Hurghada, 5–35 m, 2 spms (PS- 442, Figs. 20 F–G).— SAUDI ARABIA: Farasan Islands: Tiger Head Island, 16.791° N, 42.1987° E, 1–6 m (UF 463619).— YEMEN: Karaman Islands: Al-Uqban Island, 15°29'237"N, 42°23'782"E, 34–40 m, 5 spms (SMF 346018/5).

Distribution

The species is distributed in the whole Red Sea, from Egypt to Yemen. As far as known, the species seems to be restricted to the Red Sea.

Description

Shell medium to large-sized for genus, up to 24.0 mm, claviform shaped with 10–11 teleoconch whorls; spire 1.5 height of the aperture including canal; suture incised; siphonal canal short and stout, bent slightly to right; anal sinus moderately deep, anal sinus U-shaped, moderately deep, situated on the termination of the second spiral cord; parietal callus-pad well developed; interior of lip with about 7 fine spiral threads; stromboid notch wide and shallow.

First teleoconch whorl with three strong spiral cords, one immediately below the upper suture, the second one midwhorl and the third one somewhat above the lower suture, on later whorls several (4 to 8) very fine spiral threads are developing between the sharp and prominent primary spiral cords, middle spiral cord stronger than the upper and lower one and becoming stronger gemmulated; base of last whorl with 4–6 moderately strong and sharp spiral cords with wide interspaces, anterior canal with 4–8 rather strong and closely set spiral cords, interpaces of basal spiral cords with 5–10 very fine and regular spiral threads; no axial sculpture.

Protoconch domed, multispiral, consisting of about 3.5 whorls, first whorl smooth and glossy, remaining whorls with fine and arcute axial riblets, become stronger on the last quarter of last protoconch whorl.

Basic colouration white, interspaces between the gemmules of sinus spiral cord with regular broad dark brown blotches, the other spiral cords irregularly speckled with pale light brown to yellowish marks, sometimes (especially the spirals of the base) continuously coloured. Anterior canal usually strongly stained with purple, sometimes brown to yellowish or with pale violet hue.

Central formation of radula (Figs. 22 E–F) with three elements: very narrow rhomboid central cusp (length/ width ~5.5) and irregularly shaped trapezoid lateral elements. Lateral elements with indistinct anterior margin, broadest posterior margin. In anterior part (Fig. 22 F), lateral elements broadly spaced; in central part (Fig. 22 E), closer to central cusp. Marginal teeth ~100 µm long (1.9% AL). Major limb broad, forms distinct shallow socket for accessory limb insertion. Accessory limb subtriangular, narrow anteriorly, gradually broadens to nearly equal width of major limb. Length ~0.6 of major limb, reaches outer limit of major limb.

Remarks

Powell’s attribution of Pleurotoma erythraea to Xenuroturris was due to insufficient material which obviously consisted of a mix of true T. erythraea and Iotyrris cingulifera because he mentioned that one specimen showed the typical bifid sinus cord had no violet staining of the columella pillar and anterior canal. Turridrupa erythraea can always be distinguished from Xenuroturris and Iotyrris species by the shape of the sinus and the non-bifid sinus cord. I. cingulifera has no purplish or dark brown stain of the anterior canal, a different configuration of the spiral sculpture, a prominent bifid sinus cord and a deeper sinus with rectangular apex.

There are only two Turridrupa species which by their maculated colour pattern can be compared to T. erythraea: T. astricta (Reeve, 1843) and T. consobrina Powell, 1967 . Both these species, however, have an even shorter anterior canal, which is not stained with purple. In T. astricta only the sinus cord is maculated whereas in T. consobrina all spiral cords are maculated with smaller and denser speckles.