Turrancilla alcocki (E.A. Smith, 1906)

Kantor, Yuri, Strano, Giorgio, Vervaet, Fred, Weddingen, Mélanie & Puillandre, Nicolas, 2025, Revision of the genus Turrancilla (Neogastropoda: Olivoidea: Ancillariidae) in an integrative taxonomy framework, Zootaxa 5647 (5), pp. 401-434 : 421-424

Turrancilla alcocki (E.A. Smith, 1906)

( Figs 9D–F , 14 , 15 )

Ancilla alcocki E. A. Smith 1906: 172 .

Ancilla alcockii – Annandale & Stewart 1909: unnumbered caption page to pl., pl. 20, figs 5, 6.

Turrancilla alcocki – Tan, Islami, 2021: 321, fig. 7E.

Type material. Holotype – Zoological Survey of India, SL 38 mm (after Smith 1906).

Type locality. Andaman Is., 11°26'30"N, 92°43'45"E, 378 fms (691 m), Investigator , stn 322,

Sequenced specimens. PHILIPPINES • 1 lv; Luzon I.; 15°58'N, 121°49'E; depth 422–431 m; AURORA 2007, stn CP2658; MNHN-IM-2009-23361 (radula voucher, SL 32.1 mm) • 1 lv; Luzon I.; 15°45'N, 121°45'E; depth 562 m; AURORA 2007, stn CP2663; MNHN-IM-2009-11921

PAPUA NEW GUINEA • 1 lv; Mambare Bay ; 7°52'S, 148°1'E; depth 498–501 m; BIOPAPUA, stn CP3728; MNHN-IM-2009-22260

SOLOMON SEA • 1 lv; New Britain, Ainto Bay; 6°7'S, 149°12'E; depth 260 m; MADEEP, stn CP4331; MNHN-IM-2013-46027 • 1 lv; New Britain, Ainto Bay; 6°8'S, 149°17'E; depth 410–614 m; MADEEP, stn CP4338; MNHN-IM-2013-46396 • 1 lv; New Britain, Ainto Bay ; 6°10'S, 149°18'E; depth 510–743 m; MADEEP, stn CP4339; MNHN-IM-2013-46429

JAPAN • 1 lv; appr. 32°34′ N, 132°22′ E; from fishermen; MNHN-IM-2019-620

Non-sequenced specimens. INDONESIA • 4 lv, 5 dd; Tanimbar Is.; 08°41'S, 131°47'E; depth 410–413 m; KARUBAR, stn CP70; MNHN-IM-2023-442, MNHN-IM-2023-441 • 3 lv, 5 dd; Tanimbar Is.; 08°36'S, 131°33'E; depth 676–699 m;KARUBAR, stn CP72 • 4 lv, 3 dd; Tanimbar Is.; 08°46'S, 131°36'E; depth 451–452 m;KARUBAR, stn CP75; MNHN-IM-2023-443, MNHN-IM-2023-444 • 1 lv; Tanimbar Is.; 08°50'S, 131°33'E; depth 400–401 m; KARUBAR, stn CP76; MNHN-IM-2023-440 • 1 lv; Makassar; 00 37’S, 119 33’E; depth 675 m; CORINDON stn CH 240; MNHN-IM-2023-445.

SOLOMON ISLANDS • 3 lv, 3 dd; N Guadalcanal I.; 09°21'S, 159°56'E; depth 582–594 m; SALOMON 1, stn CP1749 • 1 lv; N Guadalcanal I.; 09°16'S, 159°55'E; depth 693–696 m; SALOMON 1, stn CP1750 • 1 lv; NE Guadalcanal I.; 09°35'S, 160°43'E; depth 367–500 m; SALOMON 1, stn CP1805 • 1 lv; SW Santa Isabel I.; 08°25'S, 159°27'E; depth 440–521m ;

SALOMON 2, stn CP2194 • 1 lv, 1 dd; SW Santa Isabel I.; 08°26'S, 159°26'E; depth 543–593 m; SALOMON 2, stn CP2195 • 1 lv; SW Santa Isabel I.; 08°26'S, 159°26'E; depth 724–765 m; SALOMON 2, stn CP2196 • 1 lv; Vella Gulf; 07°52'S, 156°51'E; depth 515–520 m; SALOMON 2 stn CP2264

PHILIPPINES • 6 dd; Luzon / Mindoro Is.; 13°40'N, 120°43'E; MUSORSTOM 2 stn CP25; MNHN-IM-2023- 446 • 6 dd; Luzon / Mindoro Is.; 13°50'N, 120°29'E; depth 441–550 m; MUSORSTOM 2 stn CP78 • 1 dd; between Ambil I. and Luzon I.; 13°48'N, 120°31'E; depth 640–688 m; MUSORSTOM 3, stn CP106 • 1 dd; between Buad I. & Panay I.; 11°50'N, 121°42'E; depth 815–821 m; MUSORSTOM 3 stn CP128 • 1 dd ; • 2 dd; Bohol Sea ; 9°27'N, 124°03'E; depth 923–1260 m; PANGLAO 2005, stn CP2352 • 1 dd; Bohol Sea; 9°24'N, 124°11'E; depth 1764–1775 m; PANGLAO 2005, stn CP2355 • 1 dd; Bohol, Sulu Sea sill; 08°49'N, 123°02'E; depth 2120–2149 m; PANGLAO 2005, stn CP2386

Description. Shell of large size for the genus (up to 50 mm with corroded apex), ovate. Protoconch and upper teleoconch whorls strongly eroded in all available specimens. spire medium low (based on least eroded specimens Fig. 14E ). Primary callus thick and covering all remaining whorls, slightly impressed at sutures; surface of callus weakly glossy, strongly microshagreened. Secondary callus thick, forming tongue-shaped pad extending to right-ventral side of last whorl and continuing up as fairly thin, reaching suture of antepenultimate whorl and following parallel to suture. Surface of secondary callus strongly microshagreened. Body whorl cloak glossy, covered by distinct spiral striation. Olivoid groove not pronounced; some specimens with very shallow depression corresponding to position of groove, usually visible only at oblique light. Rear edge of anterior band distinct, in shape of low but sharp step. Anterior band distinctly different from shell cloak in colour, darker, of different shades of brown-orange, usually with lighter narrow band adapically. Upper anterior band weakly convex, sometimes nearly flat, separated from lower anterior band by additional distinct ridge. Lower anterior band narrower, nearly flat to weakly convex and separated from plication plate by deep and broad groove. Plication plate of different morphology, with 7–8 low but distinct narrow spiral ridges ( Fig. 15A–B ) in specimens from Philippines and Japan, or 3–4 low indistinct rounded ridges in specimens from Papua New Guinea and Indonesia ( Fig. 15C–D ). Columella either smooth (in specimens with thicker columellar callus) or with very low indistinct spiral cords on columella and parietal part of last whorl. Aperture narrow oval, acute posteriorly, widest medially; outer lip sharp, slightly opisthocline, with slight rounded angulation corresponding to position of labral denticle; siphonal notch moderately deep, asymmetrical. Shell colour variable. Last whorl cloak from light to dark orange-brown, with part of the shell (usually dorsal side of last whorl) with bluish tint. Primary callus of the same shade as cloak, sometimes slightly darker. Secondary callus usually creamy on ventral part and of same shade as primary callus on dorsal side. Anterior band distinctly darker than cloak, brownish with lighter median spiral band. Plication plate white to creamy.

Operculum typical for the genus, large, dark-brown, spanning nearly entire aperture, lanceolate, thick, with terminal often broken off nucleus. Right edge narrowly thickened and separated by distinct groove running entire operculum length, broadening with operculum growth.

Radula ( Fig. 9D–F ) studied in two specimens (MNHN-IM-2009-23361– SL 32.3 mm, MNHN-IM-2023-445 – SL 36.6 mm), typical for the genus, of about 75–90 transverse rows of teeth, 10–15 nascent. Radula about 2.12–2.76 mm in length (10.4–11.5% of AL), membrane about 175–260 µm in width (0.86–1.08% of AL).

Diagnostic cox-1 sites. 'G' in the site 181, 'G' in the site 310.

Remarks. Radulae of studied specimens differ in the shape of the rachidian teeth. In MNHN-IM-2023-445 the cusps are shorter and broader ( Fig. 9F ) than in MNHN-IM-2009-23361 ( Fig. 9D–F ). The radula of the latter specimens showed heavy wear of the rachidians of 14–15 anteriormost rows of teeth ( Fig. 9E ), while lateral teeth have only slight abrasion of the tips. The species is represented in our material by a few sequenced specimens: two from the Philippines, one from Japan, and four from Papua New Guinea. Additionally, many specimens were collected in eastern Indonesia. There is significant variability in shell shape, which is largely determined by the degree of erosion of the upper whorl. Sometimes shell completely truncated with nearly flat apex and even upper part of secondary callus on last whorl can be affected by erosion. This variability produces shell outlines ranging from short and truncate to moderately elongated. Furthermore, there is a notable difference in the morphology of the plication plate, forming two morphologically distinct groupings: one from the Philippines and Japan with numerous, sharp, distinct spiral ridges, and another from Papua New Guinea and Indonesia with fewer, indistinct, rounded ridges. However, the specimens from the Philippines and Japan do not constitute a molecular clade, which prevents their separation into two species. Among the non-sequenced material from the Philippines, we found a live-collected specimen (MNHN-IM-2023-446) and several dead ones with plication plate morphology intermediate between the two forms.

The specimens from Papua New Guinea and Indonesia closely resemble the holotype (not examined but illustrated by Annandale & Stewart, 1909), differing only in their slightly more slender shells. Therefore, we apply the name T. alcocki to the molecularly defined species, at least until material suitable for sequencing can be obtained from the type locality or nearby regions. The species was also recently recorded off Java, Indonesia, by Tan & Islami (2021).

Occasionally, very pale specimens are collected in both Indonesia and the Philippines. These specimens display a light cream cloak with even lighter primary and secondary calluses, as well as a slightly darker anterior spiral line in the lower anterior band (e.g., MNHN-IM-2023-445 – Fig. 14L ).

The specimen from Japan ( Fig. 14E ) differs from all others in having a more elongated shell shape and less erosion of the upper whorls. Nevertheless, it shares the more numerous spiral ridges on the plication plate with the specimens from the Philippines, while the latter exhibit closer similarity to those from Papua New Guinea.

Distribution. From Andaman Islands to Philippines, Tanimbar Islands ( Indonesia), Papua New Guinea and Solomons ( Fig. 16 ).

Figures

FIGURE 9. Radulae of Turrancilla. A. Turrancilla glans (E.A. Smith, 1899), MNHN-IM-2023-457, Solomon Is. (shell on Fig. 8K). B–C. Turrancilla heraldei sp. nov., MNHN-IM-2023-449, Philippines (arrow indicates tongue-shaped projection of the base of posterior edge of rachidian tooth). D–E. Turrancilla alcocki (E.A. Smith, 1906), MNHN-IM-2009-23361, Philippines, SL 32.3 mm, E – anteriormost part of radula demonstrating heavy weary of teeth. F. Turrancilla alcocki (E.A. Smith, 1906), MNHN-IM-2023-445, Indonesia.

FIGURE 14. Turrancilla alcocki (E.A. Smith, 1906). A–B. Holotype, ZSL, SL 38 mm (from Annandale & Stewart, 1909: pl. 20 figs. 5, 6). C–D. Philippines, MNHN-IM-2009-11921, SL 38 mm. E. Japan, MNHN-IM-2019-620, SL 39.2 mm. F–H. Indonesia, Tanimbar Is., MNHN-IM-2023-440, SL 48.8 mm. I–K. Philippines, MNHN-IM-2009-22260, SL 32.5 mm (K – enlarged lateral apical view of the shell to show the decollation of upper whorls). L. Indonesia, Tanimbar Is., SL 36.6 mm (radula on Fig. 9F). All shells except K at the same scale.

FIGURE 15. Morphology of the plication plate of Turrancilla alcocki (E.A. Smith, 1906). A–B. Japan, MNHN-IM-2019-620, SL 39.2 mm; specimen with 8 spiral ridges on plication plate. C–D. Indonesia, MNHN-IM-2023-444, SL 41.8 mm (specimen with 4 spiral ridges).

FIGURE 16. Distribution of Turrancilla alcocki, T. monachalis, and T. apicalis in the central Indo-Pacific.