Leucosyrinx luzonica

Leucosyrinx luzonica (Powell, 1969) Figs 20F, 23A–H Comitas luzonica Powell, 1969: 269 (23-281), pl. 225 fig. 7. Type material Holotype PHILIPPINES • off Hermana Mayor I., western Luzon; 15°58′15″ N, 119°40′20″ E; depth 1719 m; Albatross, stn 5439; USNM 238476. Material examined (sequenced) PHILIPPINES • 1 lv; Luzon I.; 15°06′ N, 123°03′ E; depth 1743–1754 m; AURORA 2007, stn CP2683; MNHN-IM-2009-13440 • 1 lv; Luzon I.; 15°06′ N, 123°03′ E; depth 1762–1806 m; AURORA 2007, stn CP2689; MNHN-IM-2009-13444 • 2 lv; Luzon I.; 15°36′ N, 121°56′ E; depth 1456–1471 m; AURORA 2007, stn CP2751; MNHN-IM-2009-13469, MNHN-IM-2009-13472. SOUTH CHINA SEA • 1 lv; S off Taiwan Bank; 21°35′ N, 118°15′ E; depth 1634–1683 m; ZhongSha 2015, stn CP4163; MNHN-IM-2013-59559. Description SHELL. Medium-sized, reaching 42 mm (holotype), thin and fragile, broadly fusiform, with medium high spire, brownish-olive. Protoconch unknown. Teleoconch whorls obtusely angular on shoulder, with distinctly concave subsutural ramp. Narrowly channeled suture. 16–18 strong, slightly oblique, axial folds on and shortly below shoulder on last whorl, folds do not reach lower suture on teleoconch whorls. Well-developed spiral sculpture of similar width, rather broad, low, rounded cords over entire shell, less pronounced on subsutural ramp. Intervals between cords narrower than cords’ width. Shell base strongly convex, rapidly narrowing, smooth transition to medium-long straight canal, slightly inclined leftwards. Rather broad, elongate-oval aperture, well differentiated from canal. Columellar and parietal callus well-developed, white. deep, subsutural, broadly arcuate anal sinus extends across subsutural ramp, confluent with large forward extension of outer lip (judging from growth lines, since outer apertural lip is incomplete in all our specimens). RADULA (Fig. 20F; studied MNHN-IM-2009-13444). Comprising about 30 rows of teeth, 11–12 nascent. Marginal teeth duplex, long, ~460 µm in length (6.6% of AL without canal). Major limb narrow lanceolate, slightly curved. Accessory limb more than twice as narrow, rather flat, ~0.75 of total tooth length, inserted into deep distinct socket on dorsal side of major limb. DNA diagnosis (based on 5 cox 1 sequences) ‘T’ in site 34, ‘T’ in site 67, ‘C’ in site 85, ‘G’ in site 280. Remarks The species was originally described based on a single specimen and has not been mentioned in the literature since its original description. The reference to L. luzonica by Kantor et al. (2018) is attributed here to L. quinetae sp. nov. (see below), leaving the intraspecific variability of L. luzonica unstudied. In our material, we identified three molecularly distinct species strongly resembling the holotype of L. luzonica in shell characteristics, here referred to as L. luzonica, L. quinetae, and Leucosyrinx sp. 19. Applying the existing name to any of these species remains somewhat subjective. The two former species were collected close to the type locality (western Luzon, Philippines) – eastern Luzon and South China Sea (L. luzonica) and South China Sea (L. quinetae). One minor character shared by both specimens we attributed to L. luzonica and the holotype of this species is the pattern of the spiral sculpture. In L. luzonica, the spiral cords are closely spaced, with intervals narrower than the width of the cords, whereas in L. quinetae sp. nov., the intervals are equal to or wider than the cords’ width. Additionally, L. quinetae is significantly larger, reaching 60 mm in shell length. The third similar species, Leucosyrinx sp. 19, is represented by a single specimen and exhibits a spiral sculpture pattern similar to that of L. luzonica. However, it is smaller (SL 26.8 mm) and was collected farther from the type locality of L. luzonica – off Solomon Is. – than specimens attributed here to L. luzonica. Therefore, we attribute the Powell’s name to the species collected in the Philippines and South China Sea. Leucosyrinx luzonica also shows clear similarities to the holotype of Comitas thisbe diomedea Powell, 1969, which was described from Celebes, Indonesia, at depths of 987–1022 m. In contrast, our specimens were collected from greater depths: 1456–1762 m in the Philippines and South China Sea. Given these similarities, it is possible that L. luzonica and C. diomedea are conspecific. Nevertheless, we presently consider L. diomedea as a separate species pending study of additional material from Indonesia. Distribution Philippines to South China Sea, 1456–1743 m.