Leucosyrinx archibenthalis Powell, 1969

Kantor, Yuri I., Fedosov, Alexander & Puillandre, Nicolas, 2025, Revision of the Indo-Pacific species of the genus Leucosyrinx Dall, 1889 (Neogastropoda: Conoidea: Pseudomelatomidae), European Journal of Taxonomy 999, pp. 1-126 : 86-88

Leucosyrinx archibenthalis Powell, 1969

Figs 29C , 30

Leucosyrinx (Sibogasyrinx) archibenthalis Powell, 1969: 344 (23-412), pl. 264 figs 6–7.

Sibogasyrinx archibenthalis – Kantor & Puillandre 2021: 35 , fig. 3r–t.

Type material

Holotype

PHILIPPINES • Mindanao I., Iligan Bay, Tabu Point; 08°16′45″ N, 124°02′49″ E; depth 924 m; RV Albatross , stn 5513; USNM 238773 .

Material examined (all sequenced)

BISMARCK SEA • 2 lv; W of Tarawai Is ; 3°11′ S, 143°04′ E; depth 510–560 m; PAPUA NIUGINI, stn CP4069; MNHN-IM-2013-19304, MNHN-IM-2013-19308 .

PAPUA NEW GUINEA • 1 lv; Manus I.; 2°14′ N, 147°16′ E; depth 611–618 m; BIOPAPUA, stn CP3690; MNHN-IM-2009-17060 .

PHILIPPINES • 1 lv; Luzon I.; 15°52′ N, 121°49′ E; depth 506–542 m; AURORA 2007, stn CP2660; MNHN-IM-2009-13333 • 1 lv; Luzon I.; 16°00′ N, 121°51′ E; depth 431–442 m; AURORA 2007, stn CP2735; MNHN-IM-2009-13459 .

SOLOMON ISLANDS • 1 lv; NW of Santa Isabel I.; 7°39′ S, 157°43′ E; depth 495–650 m; SALOMON 2, stn CP2213; MNHN-IM-2009-16808 .

Description

SHELL. Medium-sized, reaching nearly 45 mm, rather solid, fusiform, nearly biconical, with high spire, from greyish to light brownish. Paucispiral small glossy protoconch, of about 1.75 whorls. Teleoconch whorls very weakly angular on shoulder, with nearly flat subsutural ramp. Suture impressed. Distinct, oblique, axial folds on shoulder, 16–18 on penultimate whorl. Folds reach lower suture on upper whorls, can be limited to rounded knobs situated just above lower suture. Folds gradually weaken on later part of penultimate whorl and absent on last whorl in larger specimens. Well-developed spiral sculpture of similar width, narrow, low, rounded, slightly wavy cords, well pronounced over entire shell. Intervals between cords narrower than cords’ width. On subsutural ramp cords broader and less sinuous than those below shoulder. Shell base weakly to medium convex gradually passing into medium-long straight 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. 29C ; examined in MNHN-IM-2009-13333). Comprising around 35 rows of teeth, 15 nascent. Marginal teeth duplex, ~220 µm in length (2.0% AL without canal). Major limb medium broad lanceolate in dorsal view, weakly curved. Accessory limb less than half of tooth width, of same width along entire length, ~0.8 of total tooth length, inserted into distinct deep ocket on dorsal side of major limb.

DNA diagnosis (based on 6 cox 1 sequences)

‘C’ in site 50, ‘A’ in site 88, ‘G’ in site 166, ‘A’ in site 304, ‘G’ in site 490.

Remarks

This species was previously known from the holotype collected off Mindanao, Philippines. Our specimens were collected from the Philippines and Papua New Guinea, albeit at shallower depths of 430–611 m compared to 924 m for the holotype. The holotype is slightly slenderer than our specimens, but this characteristic, as well as the degree of angulation of the shoulder, is subject to intraspecific variability, as confirmed by our sequenced specimens.

Previosuly, the species was assigned to Sibogasyrinx , including in the latest revision of the genus ( Kantor & Puillandre 2021). Nevertheless, the holotype lacks the diagnostic character of Sibogasyrinx – the subsutural row of knobs – and therefore can not be attributed to the genus. The newly sequenced material as well as the radular morphology confirmed its position within Leucosyrinx .

The species resembles the specimens of L. farhatorum sp. nov. from Vanuatu ( Fig. 4N–P ), and they are sister species; however, L. archibenthalis differs in having a broader shell with a more angular shoulder.

Distribution

Philippines, Papua New Guinea, Bismarck Sea, 431– 924 m.

Figures

Fig. 29. Radulae of species of Leucosyrinx Dall, 1889. A. L. lozoueti sp. nov., MNHN-IM-2013-68076, SL 8.1 mm. B. Leucosyrinx sp. 5, MNHN-IM-2009-17198, SL 10.8 mm. C. L. archibenthalis Powell, 1969, MNHN-IM-2009-13333, SL 36.7 mm. D–E. Leucosyrinx sp. 6, MNHN-IM-2009-6036, SL 15.2 mm. F. L. placaisae sp. nov., MNHN-IM-2013-48112, SL 18.6 mm. Scale bars = 100 µm.

Fig. 30. Leucosyrinx archibenthalis Powell, 1969. A–C. Holotype, USNM 238773, SL 41.8 mm. D–E. MNHN-IM-2013-19304, Bismarck Sea, 510–560 m, SL 40.7 mm. F. MNHN-IM-2009-13333, Philippines, 506–542 m, SL 36.7 mm.G. MNHN-IM-2009-13459, Philippines, 431–442 m, SL 43.4 mm. H. MNHN-IM-2009-17060, Papua New Guinea, 611–618 m, SL 29 mm. I. MNHN-IM-2013-19308, Papua New Guinea, 510–560 m, SL 38.4 mm. All shells at the same scale.

Fig. 4. A–F. Leucosyrinx floraecharlottae sp. nov.A–C. Holotype, MNHN-IM-2007-38823, SL26.0 mm. D–E. MNHN-IM-2009-17050, SL 32.7 mm.F. MNHN-IM-2009-17052, SL 24.8 mm.G–J. Leucosyrinx lemarcisi sp. nov. G–H. Holotype, MNHN-IM-2007-38823, SL 26.0 mm. I–J. MNHN-IM-2007-38850, SL 25.0 mm. K–P. Leucosyrinx farhatorum sp. nov. K–L. Holotype, MNHN-IM-2007-42503, SL 41.2 mm. M. MNHN-IM-2009-16752, SL 42.7 mm. N–P. MNHN-IM-2009-13499, SL 35.1 mm. All shells at the same scale.