Sibogasyrinx lolae, Kantor & Puillandre, 2021

Kantor, Yuri I. & Puillandre, Nicolas, 2021, Rare, deep-water and similar: revision of Sibogasyrinx (Conoidea: Cochlespiridae), European Journal of Taxonomy 773, pp. 19-60 : 43-46

Sibogasyrinx lolae sp. nov. (= PSH 8)

urn:lsid:zoobank.org:act:73404289-ED57-4ABD-A0D0-05939F095C40

Figs 8D , 9I–Q

Diagnosis

Shell medium-sized, reaching 43 mm in length, fusiform, with weakly concave, nearly smooth subsutural ramp and nodules on shoulder of upper teleoconch whorls, absent on later whorls of large specimens. Spiral sculpture weak, of closely spaced cords covering entire shell except subsutural ramp in some specimens. Radula with central tooth and longitudinally folded marginal teeth with weakly thickened edges.

Etymology

The species is named after Lola, the daughter of the second author.

Material examined

Holotype SOLOMON ISLANDS • W of San Cristobal I.; 10°26′ S, 161°20′ E; depth 506–567 m; SALOMONBOA 3, stn CP2839; MNHN-IM-2007-42537 .

Other material (all sequenced)

NEW CALEDONIA • 1 lv; Bank de L’Orne/Walpole ; 22°22′ S, 168°57′ E; depth 460–708 m; EXBODI, stn CP3864; MNHN-IM-2009-29230 • 1 lv; 21°58′ S, 167°07′ E; depth 511–1050 m; TERRASSES, stn CP3098; MNHN-IM-2009-29311 • 1 lv; Fairway Ridge ; 21°39′ S, 162°42′ E; depth 787 m; KANADEEP, stn CP4923; MNHN-IM-2013-48156 .

Description

MEASUREMENTS (holotype). SL 37.3 mm, AL (with canal) 22.9 mm, AL (without canal) 14.5 mm, SW 11.3 mm.

SHELL (holotype). Moderately thick, glossy, strong except for very fragile and partially broken outer aperture lip, narrowly fusiform, with high spire and long, narrow, straight siphonal canal. Protoconch small, globose, corroded, of about 1.5 whorls. Protoconch preserved in other juvenile specimen (MNHN-IM-2013-48156), comprising just over 1.5 strongly convex, microshagreened whorls. Protoconch/teleoconch transition indistinct, marked by appearance of axial ribs. Protoconch diameter 1.0 mm, height 0.74 mm. Spire whorls angled at shoulder, last whorl with less angular shoulder. Total teleoconch whorls just under 8. Suture shallowly impressed on last whorl and rather deep on spire whorls, subsutural ramp moderately broad, weakly concave on upper teleoconch whorls and nearly flat on penultimate and last whorls. Subsutural ramp with distinct prosocline axial wrinkles, extending from suture to upper ⅔ of ramp, 22–23 on first and second whorls, 24 on penultimate and 31 on last whorl, and without spiral sculpture on upper four whorls and later with indistinct spiral cords, three on last whorl. Shoulder of teleoconch whorls (except last one) with a row of distinct, opisthoclinely elongated nodules, intersected by weak spiral cords. Seventeen nodules on first teleoconch whorl, 18 on antepenultimate and penultimate whorls. Weak spiral cords on and below shoulder, starting from 3 rd teleoconch whorls, about twice as wide below shoulder. Penultimate whorl with four cords on shoulder and four below shoulder. Shoulder smooth on last whorl, but with about 55 cords below shoulder, of which 25 on canal. Cords weak, slightly wavy and closely spaced, their intervals about half the width of cords. Shell base gradually narrowing towards long, narrow, nearly straight siphonal canal. Aperture narrow, constricted posteriorly, with narrow, very thin parietal callus, outer lip badly broken, distinctly impressed at shoulder, weakly convex below shoulder and shallowly concave at transition to canal. Anal sinus judging from growth lines shallow, subsutural, broadly arcuate, confluent with forward extension of outer lip. Shell very light yellowish, protoconch very light tan (in holotype) and light brown in MNHN-IM-2013-48156.

ANATOMY (n = 1; MNHN-IM-2009-29311). Male. Penis tip obliquely truncated, with long and very narrow papilla, surrounded by circular fold, much larger in diameter than papilla itself. Proboscis conical, moderately long, with broad base, anterior half rapidly narrowing towards tip. Proboscis retractors distinct, arranged in two symmetrical lateral bundles, attached to inner proboscis walls at border of its posterior third. Buccal mass with small radular sac, odontophore situated within proboscis in its broader posterior part; elongate oval, occupying slightly less than half of proboscis length. Single small accessory salivary gland present. Salivary glands separate, acinous, irregular in shape. Venom gland long, moderately thick and convoluted, opening into oesophagus within the nerve ring.

RADULA (n = 1; MNHN-IM-2009-29311) ( Fig. 8D ). Short, comprising 28 rows of teeth, 13 nascent. Radula length 1.15 mm (7.9% of AL without canal), width up to 255 μm (1.8% of AL without canal), tooth length 160 μm (1.10% of AL without canal). Central tooth with subrectangular basal plate, having distinct borders and long, narrow, sharp cusp. Anterior margin overlapped by preceding row, posterior margin formed by two straight sections meeting at obtuse angle in midline. Marginal teeth flat when formed, becoming trough-shaped with weakly thickened edges during maturation, folded longitudinally when fully formed, with both margins overlapping at tooth tip. Resulting folded tooth moderately broad, with sharp pointed tip, anterior edge with a narrow slit between tooth margins. Tooth folding occurring within 15 th row of teeth.

Remarks

The largest specimen attains 43.1 mm.

Other specimens are similar to the holotype in shell shape, although some have much more pronounced spiral sculpture, especially MNHN-IM-2009-29230, which also retains spiral cords on the shoulder of the last whorl.

In shell shape and sculpture the new species is most similar to Sibogasyrinx filosa , some specimens being almost indistinguishable (e.g., holotype of S. filosa and MNHN-IM-2009-29230). Sibogasyrinx lolae sp. nov. can be distinguished from S. filosa due to its generally less distinct spiral sculpture and less concave, nearly flat subsutural ramp. Other conchologically similar species are S. cf. pyramidalis 1 and 2, but these differ in their radular morphology. In both these species and S. lolae sp. nov., the nodules on the shoulder become less pronounced or disappear on later whorls. Nevertheless, the nodules are still pronounced on the shoulder of the last whorl in specimens of S. cf. pyramidalis 1 and 2 of the same size as specimens of S. lolae sp. nov. which already lack nodules on the last whorl.

Distribution

This species is recorded from the Solomon Islands, the Coral Sea and southern New Caledonia, at depths of 460– 787 m.

Figures

Fig. 8. Radulae of species of Sibogasyrinx Powell, 1969. A–B. Sibogasyrinx sangeri Kantor, Fedosov & Puillandre, 2018, MNHN-IM-2009-16995 (shell seen on Fig. 7C). A. Part of radula with fully formed marginal teeth; white hollow arrow indicates overlapping edges of the tooth at its tip. B. Part of radula showing transition between unfolded (white arrow) and completely longitudinally folded (black arrow) marginal teeth (ae = anterior tooth edge; pe = posterior tooth edge). C. Sibogasyrinx filosa Ardovini, 2021, Solomon Islands, MNHN-IM-2009-16831 (shell seen Fig. 9E–F). D. Sibogasyrinx lolae sp. nov., MNHN-IM-2009-29311. E. Sibogasyrinx maximei sp. nov., holotype, MNHN-IM-2013-45883, anterior end of radula. F. Sibogasyrinx pagodiformis sp. nov., MNHN-IM-2009-11327.

Fig. 9. A–H. Sibogasyrinx filosa Ardovini, 2021. A–B. Holotype, Solomon Islands (MNHN- IM-2000-37629), SL 52 mm. C–D. Solomon Islands, MNHN-IM-2007-42498, SL 49.9 mm. E–F. Solomon Islands, MNHN-IM-2009-16831, SL 34.4 mm (radula seen on Fig. 8C). G–H. Papua New Guinea, MNHN-IM-2013-59044, SL 29.9 mm. I–Q. Sibogasyrinx lolae sp. nov. I–J. Solomon Islands, holotype, MNHN-IM-42537, SL 37.3 mm. K–L. New Caledonia, MNHN-IM-2009-29230, SL 43.1 mm. M–N. New Caledonia, MNHN-IM-2009-29311, SL 29.1 mm. O–Q. New Caledonia, MNHN-IM-2013-48156, SL 17.1 mm (O at the same scale as the other specimens, P–Q enlarged). All shells (except P–Q) to same scale.