Turrancilla glans (E. A. Smith, 1899)

Figs 8, 9A, 10, 12A–B

Ancilla glans E. A. Smith 1899: 246; Annandale & Stewart 1909: unnumbered caption page to pl., pl. 11 fig. 6, 6a.

Turrancilla glans – Tan & Islami 2021: 321, fig. 7F.

Type material. Holotype: Zoological Survey of India, ZSI M918/1, SL 33 mm.

Type locality. Off Andaman Is., 13°17'15"N, 93°10'E, 338 m.

Sequenced material. SOLOMON ISLANDS • 1 lv; E Santa Isabel I.; 8°17'S, 160°00'E; depth 464–523 m; SALOMON 2, stn CP2184; MNHN-IM-2007-33304 • 1 lv; E Santa Isabel I.; 8°17'S, 160°00'E; depth 487–541 m; SALOMON 2, stn CP2186 MNHN-IM-2007-33282 • 2 lv; NW Santa Isabel I.; 7°38'S, 157°42'E; depth 400–475 m; SALOMON 2, stn CP2212, MNHN-IM-2007-33316, MNHN-IM-2007-33317 • 1 lv; NW Santa Isabel I.; 7°39'S, 157°43'E; depth 495–650 m; SALOMON 2, stn CP2213; MNHN-IM-2007-33323 • 2 lv; Choiseul I.; 6°39'S, 156°14'E; depth 490–520 m; SALOMON 2, stn CP2226; MNHN-IM-2007-33295, MNHN-IM-2007-33296 • 2 lv; Choiseul I.; 6°37'S, 156°13'E; depth 508–522 m; SALOMON 2, stn CP2227; MNHN-IM-2007-33319, MNHN-IM- 2007-33320 • 1 lv; Choiseul I.; 6°35'S, 156°11'E; depth 609–625 m; SALOMON 2, stn CP2228; MNHN-IM-2007-33318 • 2 lv; Vella Gulf; 7°56'S, 156°51'E; depth 460–487 m; SALOMON 2, stn CP2262; MNHN-IM-2007- 33326, MNHN-IM-2007-33327 • 2 lv; E Guadalcanal I.; 9°19'S, 160°06'E; depth 416–425 m; SOLOMONBOA 3, stn CP2767; MNHN-IM-2009-11939, MNHN-IM-2009-11940 • 1 lv; E Guadalcanal I.; 9°36'S, 160°46'E; depth 448–523 m; SOLOMONBOA 3, stn CP2849; MNHN-IM-2007-36205 .

PAPUA NEW GUINEA • 1 lv; New Ireland; 2°24'S, 150°34'E; depth 388–572 m; KAVIENG 2014, stn DW4424; MNHN-IM-2013-58149 • 1 lv; New Ireland; 2°23'S, 150°35'E; depth 534–650 m; KAVIENG 2014, stn DW4439; MNHN-IM-2013-58320 .

Non-sequenced material. INDONESIA, Tanimbar Is. • 4 lv, 5 dd, 2 lv; 08°20'S, 132°11'E; depth 399–405 m; KARUBAR, stn CP59; MNHN-IM-2023-452 • 2 lv, 4 dd; 08°42'S, 131°53'E; depth 356–368 m; KARUBAR, stn CP69; MNHN-IM-2023-453 • 3 dd; 08°50'S, 131°33'E; depth 400–401 m; KARUBAR, stn CP76; MNHN-IM-2023-454 • 2 lv, 2 dd; 08°57'S, 131°27'E; depth 346–352 m; KARUBAR, stn CP77; MNHN-IM-2023-447, MNHN-IM- 2023-448 • 2 lv; 09°23'S, 131°00'E; depth 285–297 m; KARUBAR, stn CP83; MNHN-IM-2023-451 .

PHILIPPINES • 8 lv, 5 dd; Luzon I.; 15°58'N, 121°49'E; depth 422–431 m; AURORA 2007, stn CP2658; MNHN uncatalogued • 1 lv, 1 dd; 16°00'N, 121°51'E; 431–432 m, AURORA 2007, stn CP2735; MNHN-IM-2023- 454;

SOLOMON ISLANDS • 5 lv; N Guadalcanal I.; 09°15'S, 160°09'E; depth 477–505 m; SALOMON 1, stn CP1792; MNHN-IM-2023-454 • 1 lv; N Guadalcanal I.; 09°19'S, 160°25'E; depth 469–481 m; SALOMON 1, stn CP1796; MNHN uncatalogued • 2 lv; NW San Cristobal I.; 10°10'S, 161°22'E; depth 439–486 m; SALOMON 1, stn CP1836; MNHN uncatalogued • 6 dd; SE Santa Isabel I.; 8°17'S, 160°00'E; depth 464–523 m; SALOMON 2, stn CP2184; MNHN uncatalogued • 1 lv; SE Santa Isabel I.; 8°17'S, 160°00'E; depth 487–541 m; SALOMON 2, stn CP2186; MNHN uncatalogued • 1 lv, 1 dd; SE Santa Isabel I.; 8°18'S, 160°01'E; depth 495–677 m; SALOMON 2, stn CP2188; MNHN uncatalogued • 4 lv; SE Santa Isabel I.; 8°17'S, 160°00'E; depth 482–604 m; SALOMON 2, stn CP2187; MNHN uncatalogued • 2 lv; NW Santa Isabel I.; 7°38'S, 157°42'E; depth 400–475 m; SALOMON 2, stn CP2212; MNHN-IM-2023-457 (radula prepared), MNHN-IM-2023-458 • 1 lv; NW Santa Isabel I.; 7°42'S, 157°44'E; depth 550–682 m; SALOMON 2, stn CP2214; MNHN uncatalogued • 1 lv; Vella Gulf; 7°56'S, 156°51'E; depth 460–487 m; SALOMON 2, stn CP2262; MNHN uncatalogued .

TAIWAN • 3 lv, 1 dd; NE coast off Taschi; 24°48'N, 122°08'E; 326–331 m; TAIWAN 2001, stn CP102; MNHN uncatalogued • 1 lv; NE coast off Taschi; 24°49'N, 122°06'E; 367–424 m; TAIWAN 2001, stn CP103; MNHN uncatalogued .

Description. Shell of large size for the genus (up to 48 mm), elongate-oval. Protoconch and uppermost teleoconch whorls decollated in all available specimens, including smallest ones with shell length of only 9 mm. Spire moderately high, conical; primary callus rather thin, covering all remaining whorls; surface of callus weakly glossy, strongly microshagreened. Spiral striation visible through primary callus on apertural side of shell. Secondary callus thick, forming tongue-shaped pad extending to right-ventral side of last whorl and continuing up as thick pad reaching suture of antepenultimate whorl. Surface of secondary callus strongly microshagreened and similar to that of primary callus. Body whorl cloak glossy, covered by distinct very narrow, wavy, and closely spaced spiral striation; distinct lighter band in lower part adjoining anterior band. Olivoid groove not pronounced. Rear edge of anterior band distinct in a shape of sharp step. Anterior band usually distinctly darker than cloak, but occasionally of same colour. Upper anterior band usually very weakly convex to nearly flat, separated from lower anterior band by additional distinct ridge. Lower anterior band significantly narrower, nearly flat to weakly convex and separated from plication plate by deep and broad groove. Plication plate with 5–7, exceptionally 8 distinct narrow spiral ridges. Columella with indistinct spiral cords. Aperture narrow oval, acute posteriorly, widest medially; outer lip thickened, slightly opisthocline, sometimes with weak extension corresponding to labral denticle; siphonal notch of medium depth, asymmetrical. Columella crossed by variably distinct in colour brown spiral band corresponding to lower part of anterior band, sometimes brownish in area corresponding to upper anterior band. Shell colour variable from very pale creamy to medium dark of different shades of orange and brown, sometimes part of shell cloak with bluish tint crossed by irregular interrupting and very narrow brown lines. Primary callus usually slightly different from cloak, sometimes slightly darker. Secondary callus rose-creamy on ventral part near aperture and of same shade as primary callus on dorsal side. Upper edge of secondary callus usually highlighted by narrow darker band. Anterior band distinctly darker than cloak, brownish with still darker lower part. Plication plate white to creamy, columella intersected by brown line corresponding to lower plication plate.

Operculum large, narrow lanceolate, with terminal nucleus.

Radula (Fig. 9A) studied in one specimen (MNHN-IM-2023-457 – SL 35.1 mm), typical for the genus, of about 60 transverse rows of teeth, 5 nascent. Radula about 1.65 mm in length (0.7% of AL), membrane about 130 µm in width (0.55% of AL).

Diagnostic cox-1 sites. 'T' in the site 322, 'G' in the site 328, 'C' in the site 343.

Remarks. The species was originally described from the Andaman Islands, whereas all our sequenced specimens were collected from the Solomons and Papua New Guinea, which are considerably distant from the type locality. In addition to the sequenced specimens, we have extensive material from the Tanimbar Islands (Indonesia) that is morphologically indistinguishable (see, e.g., Fig. 8J). The species was also recently reported off Java (Indonesia), by Tan & Islami (2021). Morphologically, our specimens, as well as those illustrated by Tan & Islami, are very similar. Although the holotype is a worn and faded specimen (Fig. 8A–B), it cannot be reliably distinguished from the specimens examined and illustrated herein based on the main characters. Therefore, until conspecificity with the specimens from the type locality or nearby regions can be confidently rejected through molecular data, we apply the name T. glans to this molecularly defined species.

Turrancilla glans is quite similar to T. monachalis (Ninomiya, 1988) and T. heraldei sp. nov., both of which are molecularly distinct species. It differs from T. monachalis in attaining a larger size (the largest T. glans specimen available to us has a SL of 47.8 mm – MNHN-IM-2007-33317, while the largest T. monachalis specimen has a SL of 37 mm) and having a narrower lower part of the anterior band (average ratio lab/uab 0.29 vs. 0.43). Additionally, the species exhibit markedly different operculum morphology: in T. glans, it is typically large, spanning nearly the entire aperture, and narrow lanceolate, whereas in T. monachalis, it is small and broadly triangular. For differences with T. heraldei sp. nov., see the description of the latter species.

Distribution. From Andaman Islands to Philippines, Taiwan, Tanimbar Islands in Indonesia estward to Solomon Islands (Fig. 10).