Sinetectula egregia (Reeve, 1844) Fraussen & Vermeij, 2021

Fraussen, Koen & Vermeij, Geerat J., 2021, Sinetectula gen. nov., a new genus of Pisaniidae (Gastropoda: Buccinoidea) from the tropical Indian and Pacific Oceans, European Journal of Taxonomy 748, pp. 155-176 : 159-164

Sinetectula egregia (Reeve, 1844) gen. et comb. nov.

Figs 1–2 , 10A–C

Triton egregius Reeve, 1844a: 119 (see Fig. 10A ) (three syntypes in NHM( UK): BMNH-1967643, one of them figured by Cernohorsky 1975: 191, fig. 43).

Phos amoenus Schwengel, 1950: 81–82 , pl. 5 fig. 4 (see Fig. 10B–C ) (holotype in ANSP 186177).

Triton egregius – Reeve 1844b: pl. 18 fig. 78.

Engina egregia – Cernohorsky 1975: 191, fig. 43. — Singer & Mienis 1995: 26–27. — Dekker & Orlin 2000: 28.

Engina cf. egregia – Sharabati 1984: pl. 21 fig. 5.

Enzinopsis egregia – Dekker & Gemert 2008: 129.

Type localities

Triton egregius : “Island of Masbate, Philippines (found under stones at low water)”.

Phos amoenus: Mbega Island, Fiji Islands.

Material examined

FRENCH POLYNESIA • 1 dd; Australes Archipelago , Port de Rurutu , BENTHAUS exped. stn DW2001; 22°27′ S, 151°20′ W; depth 200–550 m; Nov. 2002; MNHN .

GUAM • 1 dd; Orote cliffs ; 1978; KF 2164 .

INDONESIA • 1 dd; Lombok , E of Gili Islands; depth 46 m; F. Lorenz leg.; Oct. 2002; KF 4004 • 1 dd; W of Tomia, Kaledupa reefs; depth 9–45 m; F. Lorenz leg.; Oct. 2001; KF 4106 • 1 lv; Alor Island, Kalabahi Harbour ; depth 5–8 m; F. Lorenz leg.; Nov. 2002; KF 4107 • 1 lv; Sulawesi, near Pulau Raja; 1°08′ N, 121°51′ E; depth 5–40 m; F. Lorenz leg.; Oct. 2003; KF 4854 (see Fig. 1I –L ) .

MARSHALL ISLANDS • 26 lv; Kwajalein, West Reef ; depth 30–35 m; F. Lorenz leg.; 1989; KF 4817 • 1 lv; Kwajalein, in cave; depth 7–20 m; local collector leg.; KF 2163 • 20 lv; Kwajalein, oceanside of West Reef, in cave; depth 12 m; F. Lorenz leg.; 1989; KF 4756 (see Fig. 1A–H ) • 1 lv; Majura Atoll , in cave; depth 1–2 m; local collector leg.; Jul. 1996; KF 2796 .

MAYOTTE • 1 dd; Pananzi Island , BENTHEDI 1977 exped. stn 32; 12°45′ S, 45°18′ E; depth 15–20 m; Mar. 1977; MNHN (see Fig. 1M–O ) .

PAPUA NEW GUINEA • 1 lv; Madang, Astrolabe Bay , PAPUA NIUGINI exped. PB14; 5°13.8′ S, 145°48′ E; depth 15 m; Nov. 2012; MNHN IM-2013-12540 (see Fig. 1P–Q ) .

SAMOA • 2 dd; western Samoa; KF 5277.

Distribution

Sinetectula egregia gen. et comb. nov. has a remarkably wide range, from eastern Africa (KF, MNHN) to India ( Kurhe et al. 2014: 5, 10), along Indonesia (KF), Japan ( Okutani 2000: 477, pl. 237 fig. 112) and Australia ( Wilson 1994: 93, pl. 10 fig. 15) to the Australes Archipelago in French Polynesia (MNHN) and the Marshall Islands (KF).

We have not studied the specimens of Sinetectula egregia gen. et comb. nov. from the Red Sea reported on by Sharabati (1984: pl. 21 fig. 5) and referred to by Singer & Mienis (1995: 26–27), Dekker & Orlin (2000: 28) and Dekker & Gemert (2008: 129), so cannot judge whether these records really belong to S. egregia gen. et comb. nov. or whether they belong to S. naevosa gen. et comb. nov. or both.

Remarks

Sinetectula egregia gen. et comb. nov. is recognisable by its characteristic colour pattern consisting of small dark brown spots situated in the space between the spiral cords where they cross the axial ribs. Occasionally, these spots are also present in the axial interspaces. These spots produce, when seen without magnification and, depending on their arrangement, a combination of moderately broad spiral bands (1 on the spire whorls and 2 on the body whorl) or dark axial blotches. This in combination with a rather rough sculpture dominated by 2 strong primary spiral cords on the spire whorls, gives the spire whorls a rather angular appearance. The colour on the spiral cords (white or pale) and spiral interspaces (usually darker) may inverse after crossing the prelabral varix, where, nearing the edge of the aperture, the spiral cords may become darker while the interspaces become paler or white (see Fig. 2C ).

The serrated edge of the outer lip deserves some closer study and is worth an extensive description. The protruding cusps are preceded by spiral interspaces while the notches are in the extension of the spiral cords. Specimens with an inversed pattern, as described in the previous paragraph, cause the optical illusion that the white spiral cords produce the white cusps (in reality it are the darker interspaces that lead the way to the white cusps).

The serrated edge shows quite some variation among the species as well as within some individuals. The spiral cords alternate between strong and slightly weaker: the original (primary) spiral cords already present on the upper spire whorls are slightly stronger than the (secondary) spiral cords that took shape along the antepenultimate whorl. As a consequence, the notch preceded by a stronger primary spiral cord is often slightly deeper than the notch preceded by a slightly weaker secondary spiral cord. This is more materialised along the basal (abapical) part of the lip (slightly above the transition from base to siphonal canal). As a result, the serrations may be arranged in pairs, causing a somewhat bilirate appearance.

The 12 th or 13 th cusp (counting from the suture) is often flanked by deeper and slightly broader notches and, as a result, accentuated (see Fig. 1B, G ). We haven’t detected any specimen where this accentuated cusp is also more protruding and surpassing the other cusps.

The protoconch is paucispiral, consisting of 1¼ whorl with a rather flattened shape (see Fig. 1D–E, O ). The number of protoconch whorls is remarkably constant among all material we studied, with the exception of a single specimen from Sulawesi (KF 4854) that has 1¾ protoconch whorls (see Fig. 1L ). This shell is identical to other shells, including the shape of its protoconch, apart from the fact that the last protoconch whorl continues turning another half whorl. We counted the number of spiral cords according to the method of Verduin (1977). Other methods, for example following the suture in between the protoconch whorls, may be responsible for the 2 protoconch whorls counted in Phos amoenus by Schwengel (1950: 81). The slightly eroded apex of dead-collected but otherwise fresh looking specimens (for example KF 2164 from Guam) may have the sculpture along the first teleoconch whorl smoothened in such a subtle way that the protoconch appears larger and with more whorls.

In some specimens, the adapical apertural knob, inside the apertural lip, may be situated slightly more adapically than the parietal knob on the columella, resulting in a somewhat skewed anal notch, rather than having both anal knobs aligned.

For the description of the radula, we refer to the diagnosis under Sinetectula gen. nov. above.

Sinetectula naevosa gen. et comb. nov. differs from S. egregia gen. et comb. nov. by its larger protoconch (0.9 mm long and 0.9 mm in diameter (KF 5029) vs 0.6 to 0.7 mm long and 0.7 to 0.8 mm in diameter in S. egregia gen. et comb. nov.), the slightly higher number of protoconch whorls (1½ instead of usually 1¼), the upper spire whorls that are higher and increase in size more quickly, resulting in a slenderer spire (whereas in S. naevosa gen. et comb. nov. the transition from 3 rd to 4 th whorl falls within the first 5 mm of the teleoconch length, in S. egregia gen. et comb. nov. this occurs from the 4 th to 5 th whorl that falls within these first 5 mm). The spiral sculpture of S. naevosa gen. et comb. nov. is finer, starting with 3 finer primary spiral cords on the first teleoconch whorls (instead of 2 dominant ones), resulting in a more convex shape of the upper spire whorls. The secondary spiral cords, to the contrary, are slightly stronger when situated in the center between the primary spiral interspaces in S. naevosa gen. et comb. nov. but lower in number (1 to 3 vs 4 or 5 in S. egregia gen. et comb. nov.). By contrast, the number of secondary spiral cords on the subsutural slope is higher in number in S. naevosa gen. et comb. nov. The axial ribs are weaker but slightly higher in number, especially on the spire whorls.

Sinetectula farinosa gen. et comb. nov. differs from S. egregia gen. et comb. nov. by its higher number of protoconch whorls, the much broader shape with shorter spire and slightly more convex whorls,

the more cancellate sculpture with stronger spiral cords and axial ribs that are covered by pronounced incremental lamellae, sharper denticles on the columella and fewer (5 to 8) but stronger knobs inside the outer lip.

Figures

Fig. 1. Sinetectula egregia (Reeve, 1844) gen. et comb. nov. A–E. Specimen from the Marshall Islands, Kwajalein Atoll, in cave at Oceanside of West reef, depth 12 m, 12.0 mm long (KF 4756). F–H. Specimen with same collection data as for preceding, 14.5 mm long (KF 4756). I–L. Specimen from Indonesia, Sulawesi, 1°08′ N, 121°51′ E, near Pulau Raja, depth 5–40 m, 16.9 mm long (KF 4854). M–O. Specimen from Mayotte, Pananzi Island, BENTHEDI 1977 stn 32, 12°45′ S, 45°18′ E, depth 15–20 m, 15.0 mm long (MNHN). P. Specimen from Papua New Guinea, Madang, Astrolabe Bay, PAPUA NIUGINI stn PB14, 5°13.8′ S, 145°48′ E, depth 15 m, 16.6 mm long (MNHN IM-2013-12540). Q. Radula of preceding specimen. A–P. Images courtesy of MNHN – Alexandre Lardeur. Q. Image courtesy of Yuri Kantor. Scale bars: D–E, L, O = 2.0 mm; Q = 100 µm.

Fig. 2A–C. Sinetectula egregia (Reeve, 1844) gen. et comb. nov., in situ, Marshall Islands, Kwajalein Atoll, images courtesy of Jeanette Johnson, © 2015 In-Depth Images Kwajalein.

Fig. 10. Original figures and types. A. Syntype ofTriton egregius Reeve, 1844, original figure taken from Reeve (1844b: pl. 18 fig. 78). B–C. Types of Phos amoenus Schwengel, 1950, taken from Schwengel (1950: pl. 5 fig. 4). B. Holotype, 15 mm long. C. Paratype, 13–14 mm long. D. Type of Buccinum cinis Reeve, 1846, original figure taken from Reeve (1846: pl. 11 no. 84). E. Syntype of Caducifer? thaleia Pilsbry & Lowe, 1932, original figure taken from Pilsbry & Lowe (1932: pl. 6 fig. 6), 26.3 mm long. F–G. Lectotype of Hindsia angicostata Pease, 1860, taken from Kay (1965: pl. 1; figs 15–16), 15.5 mm long. H. Syntype of Pisania naevosa Martens, 1880, original figure taken from Martens (1880: pl. 20 fig. 8), 16 mm long. I–Q. Syntypes of Pisania naevosa Martens, 1880, MFN, ZMB/Moll-22029, images courtesy of Christine Zorn, Berlin. I–K. 16.3 mm long. L–M. 15.1 mm long. N–O. 14.9 mm long. P–Q. 16.3 mm long. R. Type of Buccinum nigricostatum Reeve, 1846, original figure taken from Reeve (1846: pl. 10 fig. 73). S. Holotype of Pollia shepstonensis Tomlin, 1926, original figure taken from Tomlin (1926: pl. 16 fig. 4), 24 mm long. T. Holotype of Pollia shepstonensis Tomlin, 1926, NHM(UK) 1926.12.6.6, image courtesy of Yves Terryn, 24 mm long.