Leucosyrinx margaritae (E.A. Smith, 1904) comb. nov.

Figs 14E–L, 15A–B

Pleurotoma (Surcula) margaritae E.A. Smith, 1904: 458 .

Pleurotoma (Surcula) margaritae – Annandale & Stewart 1909: pl. 14 figs 2, 2a.

Comitas margaritae – Powell 1969: 268 (23–280), pl. 217 figs 1–2. — Tan & Islami 2021: 325–326, fig. 9d.

Type material

Holotype ANDAMAN ISLANDS • off Andaman Is.; depth 405 ftm (= 740 m); ZSI, M 3061/1.

Other material examined (all sequenced)

PAPUA NEW GUINEA • 1 lv; Woodlark Is.; 9°12′ S, 152°16′ E; depth 556–645 m; BIOPAPUA, stn CP3740; MNHN-IM-2009-17151 .

PHILIPPINES • 1 lv; off Luzon I.; 14°55′ N, 123°12′ E; depth 944–1004 m; AURORA 2007, stn CC2702; MNHN-IM-2009-13446 .

SOLOMON SEA • 1 lv; N Long I.; 5°10′ S, 147°3′ E; depth 724 m; PAPUA NIUGINI, stn CP3982; MNHN-IM-2013-19747 • 1 lv; Vitiaz Strait; 6°00′ S, 147°36′ E; depth 706–715 m; PAPUA NIUGINI, stn CP3995; MNHN-IM-2013-19853 • 1 lv; SE of Tuam Is; 6°04′ S, 148°12′ E; depth 500–575 m; PAPUA NIUGINI, stn CP4009; MNHN-IM-2013-19931 • 1 lv; Induna I.; 4°35′ S, 152°25′ E; depth 575–616 m; MADEEP, stn CP4266; MNHN-IM-2013-45439 .

Description

SHELL. Large, reaching 60 mm. fusiform, with high spire, thin but solid, from very light yellowish to tan in color. Paucispiral small protoconch of 1.5 convex evenly rounded smooth whorls. Upper teleoconch whorls distinctly angulated on shoulder, last whorl in larger specimens nearly evenly rounded with shoulder slightly accentuated by obtuse keel. Subsutural ramp distinctly concave on upper whorls, can be nearly flat on last whorl. Strong, oblique, broad, and rounded axial folds on shoulder of teleoconch whorls. Folds fade on subsutural ramp, strongly weaken towards lower suture, not reaching it on penultimate whorl in large specimens. On the last and posterior part of penultimate whorls folds progressively weaken towards aperture. 14 folds were discernible on last whorl in largest studied specimen (SL 53.1 mm – Fig. 14J–L). Medium developed spiral sculpture, practically absent on ramp, but more distinct below shoulder, of variable in width, low, rounded, and wavy cords, with intervals similar or exceeding cords’ width. Shell base strong to weakly convex, smooth transition to long canal. Narrow, elongate-oval aperture, poorly differentiated from canal. Deep, subsutural, broadly arcuate anal sinus extends across subsutural ramp, confluent with large forward extension of outer lip.

RADULA (Fig. 15A–B; studied in two specimens, MNHN-IM-2009-13446 (Fig. 15A) and MNHN-IM-2013-19931 (Fig. 15B)). Morphologically similar in both specimens. Marginal teeth duplex, ~195– 390 µm (2.8–3.1% AL without canal). Major limb medium narrow lanceolate in dorsal view, curved. Accessory limb constitutes about half of tooth width, inserted into distinct medium deep socket on dorsal side of major limb.

DNA diagnosis (based on 6 cox 1 sequences, low confidence)

‘G’ in site 139, ‘G’ in site 313, ‘C’ in site 401, ‘G’ in site 490, ‘C’ in site 523.

Remarks

The species is moderately variable in shell outline and sculpture pattern. Although the best ASAP partition recognizes the six sequenced specimens as a single species, the phylogenetic tree has low support of this node (PP = 0.87, but the bootstrap support is 99). Within the clade two subclades with higher support (0.94 and 0.99) are recognized, both containing specimens collected in the Solomon Sea. We may deal with species in status nascendi, but since the material is rather limited, we consider it as a single species.

We apply the name L. margaritae with some reservation. Our specimens have similar size (53 vs 60 mm in the holotype), were collected at similar depths (556–944 vs 740 m) and have a rather similar shell outline. Nevertheless, the spiral sculpture is more pronounced in the holotype (Fig. 14E–F), in which the spiral cords are distinct also on the subsutural ramp. Due to the limited material it is impossible to decide at the moment whether this difference is of intra- or interspecific significance. The specimen illustrated by Tan & Islami (2021: fig. 9d) is more similar to our specimens than to the holotype in terms of sculpture, but seemingly has eroded shell surface. Leucosyrinx in general is characterized by the presence of numerous alike species, hardly if even distinguishable morphologically. Therefore, application of existing names to the species is subjective, but in this case we prefer to use the existing name rather than describing a new very similar species.

In shell outline the species resembles L. legalli sp. nov., but L. margaritae differs in its much larger size.

Distribution

From Andaman Is., off Java, to the Philippines, Papua New Guinea, and Solomon Sea, 556– 944 m.