**Remarks**

The species is known only from the immature holotype (SL 13 mm).

The shell shape, sculpture pattern, and the shape of the subsutural anal sinus fit well within the variability observed in the species of *Leucosyrinx* as defined here. The lack of the nodules on the shoulder of the last whorl is a character found in different species of *Leucosyrinx*. Given that the anal sinus shape aligns more closely with species of *Leucosyrinx* than with *Comitas*, we propose transferring the species to the former genus.

**Distribution**

Known only from type locality.

*Leucosyrinx anteridion* (Watson, 1881) comb. nov.
Fig. 32B

*Pleurotoma (Surcula) anteridion* Watson, 1881: 399.

*Pleurotoma (Surcula) anteridion* – Watson 1886: 295, pl. 19 fig. 6.

*Surcula anteridion* – Thiele 1925: 188 (222), pl. 24(36) fig. 13.

*Comitas anteridion* – Powell 1969: 273 (23-285), pl. 219 fig. 5.

**Type material**

**Holotype**

SOUTH AFRICA • off Cape of Good Hope; 34°04′ S, 18°37′ E; depth 150 ftm (= 274 m); HMS *Challenger* stn 142; NHMUK, NHMUM 1887.2.9.977.

**Remarks**

The shell shape, sculpture pattern, and the shape of the subsutural anal sinus fit well within the variability observed in the species of *Leucosyrinx* as defined here. Given that the anal sinus shape aligns more closely with species of *Leucosyrinx* than with *Comitas*, we propose transferring the species to the former genus.

**Distribution**

Off South Africa, 270–420 m. The record of Thiele (1925) from New Amsterdam, South Indian Ocean requires confirmation.

*Leucosyrinx arcana* (E.A. Smith, 1899) comb. nov.
Fig. 32C

*Pleurotoma (Surcula) arcana* E.A. Smith, 1899: 239.

*Pleurotoma (Surcula) arcana* – Annandale & Stewart 1909: pl. 9 figs 6, 6a.

*Comitas arcana* – Powell 1969: 272 (23-284), pl. 219 figs 6–7, with query. — Tan & Islami 2021: 325, fig. 9a.

**Type material**

**Syntypes**

ANDAMAN ISLANDS • 1 spec.; off Andaman Is.; 13°17′15″ N, 93°10′ E; depth 185 ftm (= 340 m); ZSI, M 926/1 • 1 spec.; off Travancore coast; 9°29′34″ N, 75°38′ E; depth 360 ftm (= 660 m); ZSI, M 926/1.
<figure><img src="image_34.png" /><figcaption>**Fig. 32.** Types of species of *Leucosyrinx* Dall, 1889 known only from empty shells. A. *L. aequatorialis* Thiele, 1925, holotype, SL 13 mm (from Thiele 1925). B. *L. anteridion* (Watson, 1881) comb. nov., holotype, SL 22.1 mm (images by Aimee McArdle, NHMUK Photographic Unit). C. *L. arcana* (E.A. Smith, 1899) comb. nov., syntype, ZSI, M 926/1, SL 25.0 mm (from Annandale & Stewart 1909: pl. 9 fig. 6–6a). D. *L. curviplicata* (Sysoev, 1996) comb nov., holotype NHMUK 1993092, SL 32.4 mm (images by Aimee McArdle, NHMUK Photographic Unit). E. *L. eurina* (E.A. Smith, 1899) comb. nov., paratype NHMUK 1904-6-15-139, SL 39 mm (photo courtesy of NHMUK). F. *L. halicyria* (Melvill, 1904) comb. nov., holotype, NHMUK 1905-7-14-49, SL 32.0 mm. G. *L. julia* Thiele, 1925, syntype, ZMB Mol 109379, SL 10.6 mm (photo courtesy of Museum für Naturkunde). H. *L. pagodaeformis* (Schepman, 1913) comb. nov, figured syntype, NATURALIS, ZMA.MOLL.137728, SL 28.7 mm (photo courtesy of K. Hasegawa). Shells not to scale.</figcaption></figure>
**Remarks**

Judging from the illustration in Annandale & Stewart (1909) the shell is rather similar to some of the molecularly confirmed species of *Leucosyrinx*, e.g., *L. quinetae* sp. nov. (Fig. 24) and some specimens of *L. luzonica* (Fig. 23). The position of the anal sinus, occupying the entire subsutural ramp, suggests the inclusion in *Leucosyrinx* rather than in *Comitas* and we transfer the species to *Leucosyrinx*.

Sysoev (1996: figs 46–47) illustrated two specimens from the Gulf of Oman and the Gulf of Aden, identified by him as *Comitas paupera* (see below), which are very similar to the type of *L. arcana* and probably belong to this species. These specimens were collected at significantly larger depths, 1890–2000 m. This assumption is based only on the shell characters and needs confirmation by anatomical and molecular data.

**Distribution**

From Gulf of Aden to Andaman Is. and Indonesia from 340 to 2000 m.

*Leucosyrinx curviplicata* (Sysoev, 1996) comb. nov.
Fig. 32D

*Comitas curviplicata* Sysoev, 1996: 10, fig. 29.

**Type material**

**Holotype**

INDIAN OCEAN • Gulf of Aden; depth 1270 m; John Murray Expedition, stn 184; NHMUK 1993092.

**Paratype**

INDIAN OCEAN • 1 spec., same data as for holotype; NHMUK 1993093.

**Remarks**

According to the subsutural position and shape of the anal sinus that occupies entire subsutural ramp, the species should be transferred to *Leucosyrinx*. It resembles *Leucosyrinx* sp. 20 (Fig. 11I), differing in the shorter spire.

**Distribution**

Type locality.

*Leucosyrinx diomedea* (Powell, 1969) comb. nov.
Fig. 23J–L

*Comitas thisbe diomedea* Powell, 1969: 277 (23-289), pl. 225 figs 3–4.

**Type material**

**Holotype**

SULAWESI • Celebes (Sulawesi), off Tg. Lamulul, Gulf of Boni; 04°53'45" S, 121°29' E; depth 540 ftm (= 987 m); *Albatross* stn 5650; USNM 239425.

**Remarks**

The species is known from two specimens, collected off Sulawesi, Indonesia. It is rather similar to *L. luzonica*, differing in the more gradual narrowing of the last whorl towards the canal. It may represent a form of *L. luzonica*, but due to very limited material on both species, we are taking a conservative approach and consider it a separate species. Conchologically, it is very different from *L. thisbe* (Fig. 17A–
E) in that its axial folds do not extend to the shell base, it has weaker spiral sculpture, lacks a subsutural fold, and has a slenderer shell. Therefore, we consider it a valid species.

Kosuge (1992: pl. 59 figs 6–7) illustrated a very slender specimen under this name, the identity of which cannot be determined with certainty based on the provided photograph. The radular drawing (Kosuge 1992: figs 17–21) shows duplex marginal teeth, which are typical of *Leucosyrinx*.

**Distribution**

Sulawesi to (?) western Australia, 496–987 m.

*Leucosyrinx herilda* (Dall, 1908)
Fig. 33F

*Gemmula herilda* Dall, 1908: 266.

*Leucosyrinx herilda* – McLean 1971b: sp. 1670.

**Type material**

**Holotype**

GULF OF PANAMA • depth 1672 ftm (= 3057 m); USNM 123091.

**Remarks**

The holotype of the species is a dead-collected incomplete shell (SL 18+ mm). Judging from the growth lines, the shape of the anal sinus corresponds to that of other species of *Leucosyrinx*. Therefore, we confirm its generic position in *Leucosyrinx*, as was suggested by McLean (1971b).

The species is very similar to *Leucosyrinx powelli* (Rehder & Ladd, 1973) collected at Agassiz Guyot in the central Pacific albeit at shallower depths (1581–1617 m). Both species can be conspecific, but due to the large distance between the type localities and large difference in depths, we presently consider them as two separate species.

**Distribution**

Type locality.

*Leucosyrinx eurina* (E.A. Smith, 1899) comb. nov.
Fig. 32E

*Pleurotoma (Surcula) eurina* E.A. Smith, 1899: 239.

*Pleurotoma (Surcula) eurina* – Annandale & Stewart 1909: pl. 9 figs 4, 4a.

*Comitas eurina* – Powell 1969: 268 (23-280), pl. 217 figs 4–5. — Tan & Islami 2021: 325, fig. 9b.

**Type material**

**Holotype**

INDIAN OCEAN • Travancore coast; depth 430 ftm (= 790 m); *Investigator*, stn 232; ZSI, M 647/1.

**Paratype**

INDIAN OCEAN • 1 spec.; same data as for holotype; NHMUK 1904.6.15.139.
**Remarks**

The shell of *L. eurina* is unusual for the genus due to the distinct subsutural spiral fold, a feature somewhat similar to what is observed in our sequenced specimen of *L. thisbe* (Fig. 17C-E). On the other hand, the anal sinus is subsutural and occupies entire subsutural ramp, thus suggesting the transfer of the species from *Comitas* to *Leucosyrinx*.

**Distribution**

From off southern India to Indonesia, 790–940 m.

*Leucosyrinx granuloplicata* (Kosuge, 1992) comb. nov.
Fig. 12G

*Comitas granuloplicata* Kosuge, 1992: 166, pl. 58 fig. 9.

**Type material**

**Holotype**

WESTERN AUSTRALIA • off Port Hedland; 17°58′ S, 118°25′ E; depth 376 m; WAM S14436.

**Remarks**

The species was described based on two specimens. However, only the holotype, which is a dead-collected and heavily worn shell lacking the protoconch and upper teleoconch whorls, with a shell length of 35.3 mm, was illustrated. The shell morphology, including the shape and position of the subsutural anal sinus extending across the subsutural ramp, allows for confident placement in the genus *Leucosyrinx*. For differences from *L. claviforma*, see the Remarks section of that species.

**Distribution**

Western Australia, 376–494 m.

*Leucosyrinx halicyria* (Melvill, 1904) comb. nov.
Fig. 32F

*Pleurotoma (Surcula) halicyria* Melvill, 1904: 164–165, pl. 10 fig. 16.

*Comitas halicyria* – Powell 1969: 286 (23-298), pl. 220 fig. 4, with query.

*Pleurotoma (Surcula) halicyria* – Kantor et al. 2022: fig. 12b.

**Type material**

**Holotype**

INDIAN OCEAN • 1 spec., SL 32.0 mm; Gulf of Oman; 24°49′ N, 56°56′ E, 225 ftm (= 411 m), NHMUK 1905-7-14-49.

**Remarks**

The species is known only from the holotype. There are no sequenced species of *Leucosyrinx* that resemble *L. halicyria*. We attribute it to the genus with some doubts, but remove it from *Comitas* on the basis of the shape and position of the subsutural anal sinus, occupying the entire subsutural ramp, like in other *Leucosyrinx* spp.

**Distribution**

Type locality.
*Leucosyrinx julia* Thiele, 1925
Fig. 32G

*Leucosyrinx julia* Thiele, 1925: 202 (236), pl. 24(36) fig. 24.

*Leucosyrinx julia* – Powell 1969: 338 (23-402), pl. 257 figs 4–5.

**Type material**

**Syntypes**

EAST AFRICA • 4 specs; off Brawa; 1°40′ S, 41°47′ E; depth 693 m; *Valdivia*, stn 251; ZMB Mol 109379.

**Remarks**

The largest type specimen has a SL of 10.6 mm, appears to be adult, and was illustrated by Thiele (1925). Conchologically, it possesses all the characteristics of *Leucosyrinx*. The original illustration shows a strongly angular shell base, although it is somewhat more obtuse in the actual specimen. In shell outline and size, it resembles *L. lozoueti* sp. nov., which, however, has a different spiral sculpture with much finer, uniformly spaced cords. Powell (1969) attributed several specimens to this species with shell lengths up to 53 mm, collected by the John Murray expedition in the Gulf of Aden at a depth of 1040 m.

**Distribution**

East Africa to Gulf of Aden, 693–1040 m.

*Leucosyrinx kirai* (Powell, 1969) comb. nov.
Fig. 26L

*Comitas kirai* Powell, 1969: 279 (23-291), pl. 223 figs 4–6.

*Comitas kirai* – Kira 1972: 101, pl. 36 fig. 7. — Hasegawa *et al.* 2000: 633, pl. 315 fig. 71. — Higo *et al.* 2001: pl. 102 fig. g3535 (holotype).

**Type material**

**Holotype**

JAPAN • Kii; ANSP 232552.

**Remarks**

The species is very similar both in shell shape and particularly in spiral sculpture to *L. breviplicata*. It is unusually small for *Comitas* (attaining 40 mm) and in general shell characters matches those of species of *Leucosyrinx*, including the subsutural position of the anal sinus that occupies the entire subsutural ramp. We conditionally transfer it to *Leucosyrinx*, pending data on the radular morphology. Although by shell characters it can be synonymized with *L. breviplicata*, it inhabits much shallower depths (50–400 m – Hasegawa *et al.* 2000: 633). In the absence of sequenced material from Japan, we consider it a distinct species.

Tan & Islami (2021: fig. 9c) illustrated a specimen from Indonesia as *Comitas kirai*. The identification of the specimen is not straightforward. The shell is much darker, as illustrated in other publications, and the spiral cords on the last whorl are very closely spaced. It may represent a separate species.

**Distribution**

Japan, 50–400 m, ?Indonesia.
*Leucosyrinx melvilli* (Schepman, 1913) comb. nov.
Fig. 17I–J

*Surcula melvilli* Schepman, 1913: 422, pl. 27 fig. 7.

*Comitas melvilli* – Powell 1969: 269 (23-281), pl. 217 figs 6–7. — Sysoev 1997: 347.

**Type material**

**Syntypes**

TIMOR SEA • 2 specs; 10°48.6' S, 123°23.1' E; depth 918 m; *Siboga*, stn 300; NATURALIS, ZMA. MOLL.174487, ZMA.MOLL.137982 (Fig. 17I–J) • 1 spec.; near Kei Is.; 5°53.8' S, 132°48.8' E; depth 560 m; *Siboga*, stn 262; NATURALIS, ZMA.MOLL.137981.

**Remarks**

Schepman (1913) did not designate the holotype, and mentioned three specimens in the original description. Nevertheless, Schepman specified that “The specimen from stn 262 is a smaller, much worn shell, of somewhat doubtful character” (560 m, near Kei Is., 5°53.8' S, 132°48.8' E, *Siboga* stn 262). It should be considered that Schepman expressly excluded it from the type series (Art. 72.4.1 of ICZN). He provided the measurements for a single specimen (SL 62 mm), which was also illustrated on pl. 27 fig. 7. The same specimen is illustrated herein.

The shell shape, sculpture pattern, and the shape of the subsutural anal sinus fit well within the variability observed in the species of *Leucosyrinx* as defined here. This species exhibits similarities to *Leucosyrinx jeedara* from Australia, albeit with notable differences in size (up to 62 mm versus 31 mm), a lower last whorl, a taller spire, and a cream coloration. Given that the anal sinus shape aligns more closely with species of *Leucosyrinx* than with *Comitas*, we propose transferring the species to the former genus.

**Distribution**

Timor Sea, 918 m.

*Leucosyrinx pagodaeformis* (Schepman, 1913) comb. nov.
Fig. 32H

*Drillia pagodaeformis* Schepman, 1913: 45 (409), pl. 26 fig. 5a–b.

*Comitas pagodaeformis* – Powell 1969: 271 (23-283), pl. 219 figs 1–2. — Kosuge 1992: 167, pl. 59 figs 4–5.

**Type material**

**Syntypes**

INDONESIA • 1 spec.; Halmahera Sea; 0°59.1' S, 129°28.8' E; depth 411 m; NATURALIS • 1 spec.;
near Kei Is.; 5°26.6' S, 132°32.5' E; depth 397 m; NATURALIS.

**Remarks**

The figured syntype (Fig. 32H, SL 28.7 mm) demonstrates all conchological characteristics of *Leucosyrinx*, including a subsutural anal sinus occupying the entire subsutural ramp. Therefore, the species is transferred to *Leucosyrinx*. It is most similar to *L. breviplicata*, differing in the more broadly-spaced spiral cords on the shell periphery.

**Distribution**

Indonesia to NW Australia, 300–411 m.
*Leucosyrinx palawanica* (Powell, 1969) comb. nov.
Fig. 33A

*Comitas aequatorialis palawanica* Powell, 1969: 282 (23-294), pl. 225 figs 5-6.

**Type material**

**Holotype**

PHILIPPINES • Palawan Passage; 10°46'40" N, 118°29' E; depth 515 ftm (= 941 m); *Albatross*, stn 5350; USNM 237910.

**Remarks**

The species is known from a single holotype with SL of 43.5 mm. The shell sculpture pattern and the shape of the subsutural anal sinus fit well within the variability observed in species of *Leucosyrinx* as defined here. Therefore, we transfer the species to *Leucosyrinx*. Originally, it was described as a subspecies of *L. aequatorialis* Thiele, 1925, but differs markedly in size (43.5 mm vs 13 mm). Additionally, in *L. aequatorialis*, the last whorl lacks axial ribs and a shoulder carina, while the carina is well-developed in *L. palawanica*. Therefore, we consider it a separate species.

**Distribution**

Type locality.

*Leucosyrinx paupera* (Watson, 1881) comb. nov.
Fig. 33B-D

*Pleurotoma (Drillia) paupera* Watson, 1881: 411.

*Pleurotoma (Typhlomangelia) paupera* – Watson 1886: 317, pl. 25 fig. 3.

*Turricula paupera* – Powell 1969: 244 (23-238), pl. 202.

*Comitas paupera* – Sysoev 1996 (part.): 8, figs 42, 45, 48 (non figs 43 = Borsoniidae gen. sp., 44, 46–47 = *Leucosyrinx arcana*).

**Type material**

**Lectotype**

INDONESIA • Arafura Sea, Aru I., 5°41′ S, 134°04′30″ E; depth 800 ftm (= 1463 m); HMS *Challenger*, stn 191; NHMUK 1887.2.9.1009.

**Paralectotypes**

INDONESIA • 2 specs; same data as for lectotype: NHMUK 1887.2.9.1010, 1887.2.9.1011.

**Remarks**

As evident from the synonymy, determining the generic position of this species is not straightforward. The type series likely comprises three species. The lectotype (Fig. 32B) was probably first designated by Powell (1969: 244) in the table of measurements. Although the specimen with the SL of 40.1 mm is significantly damaged, we tentatively attribute it to *Leucosyrinx* based on the general shell shape, sculpture, and position of the anal sinus. The paralectotype NHMUK 1887.2.9.1010 (Fig. 33C, SL 33.3 mm) differs from the lectotype by having much less pronounced axial sculpture, the presence of dendritic spiral threads, and a lower position of the shallow anal sinus, which extends below the limits of the subsutural ramp. Additionally, it shows traces of an obtuse columellar fold, and the inside of the aperture is orange. In our opinion, this specimen may belong to the family Borsoniidae. Finally, the paralectotype NHMUK 1887.2.9.1011 (Fig. 33D, SL 18.5 mm) may be a juvenile specimen of *Leucosyrinx arcana*.
<figure><img src="image_35.png" /><figcaption>**Fig. 33.** Types of species of *Leucosyrinx* Dall, 1889 known only from empty shells. *A. L. palawanica* (Powell, 1969) comb. nov., holotype USMNM 237910, SL 43.5 mm. **B–D. L. paupera** (Watson, 1881) comb. nov. **B. Lectotype**, NHMUK 1887.2.9.1009, SL 40.1 mm. **C. Paralectotype** NHMUK 1887-2-9-1010, SL 33.3 mm (= Borsoniidae, genus and species uncertain). **D. Paralectotype** NHMUK 1887-2-9-1011, SL 18.5 mm (= *L. arcana*). **E. L. undosa** (Schepman, 1913) comb. nov., holotype, NATURALIS, ZMA.MOLL.136841, SL 29.5 mm (photo courtesy of K. Hasegawa). **F. L. erilda** (Dall, 1908), holotype, USNM 123091, SL 18 mm (photo courtesy of USNM). **G. L. powelli** (Rehder & Ladd, 1973), holotype, USNM 703267, SL 13.0 mm (photo courtesy of USNM). **H. L. suratensis** (Thiele, 1925), holotype, ZMB Moll 60072, SL 16.6 mm (photo courtesy of Museum für Naturkunde). Shells not to scale.</figcaption></figure>
**Distribution**

Indonesia, Gulf of Aden, and Gulf of Oman, 1463–2000 m.

*Leucosyrinx powelli* (Rehder & Ladd, 1973)
Fig. 33G

*Comitas powelli* Rehder & Ladd, 1973: 45, pl. 3 figs 11–12.

**Type material**

**Holotype**

PACIFIC OCEAN • Agassiz Guyot; 17°58.5′ N, 178°14.2′ E; depth 865–884 ftm (= 1581–1617 m); USNM 703267.

**Remarks**

The holotype is the only known specimen, with SL 13.0 mm. Although the outer lip of the aperture is broken, judging from the growth lines, the shape of the anal sinus corresponds to that of other species of *Leucosyrinx* as defined here. The species is very similar if different from *Leucosyrinx herilda* (Dall, 1908) (see Remarks to *L. herilda*).

**Distribution**

Type locality.

*Leucosyrinx turrita* Sysoev, 1990

*Leucosyrinx turritus* Sysoev, 1990: 247, pl. 2 figs 3–4.

**Type material**

**Holotype**

PACIFIC OCEAN • Sala-y-Gomes Ridge; 25°59.8′ S, 100°40′ W; depth 330–350 m; ZMMU Lc-5733.

**Remarks**

The species was described based on four empty shells, the largest (holotype) with SL 30.0 mm. In general shell characters, including the position of the anal sinus, the species is referable to *Leucosyrinx*.

**Distribution**

Type locality.

*Leucosyrinx suratensis* (Thiele, 1925)
Fig. 33H

*Surcula suratensis* Thiele, 1925: 180 (214), pl. 23(35) fig. 19.

*Surcula coreanica* (Adams & Reeve, 1848) (not of Adams & Reeve 1850) – von Martens 1904: 80, pl. 2 fig. 3.

? *Leucosyrinx suratensis* – Powell 1969: 340 (23-404), pl. 259 figs 1–2.

**Type material**

**Holotype**

INDONESIA • off north Sumatra; 5°23′ N, 94°48′ E; depth 1024 m; ZMB Moll 60072.
**Remarks**

The holotype measures 16.6 mm in shell length and exhibits significant shell breakage followed by subsequent repair, resulting in an exaggeratedly deep anal sinus. Von Martens (1904) illustrated only the lateral view of the shell. The remaining intact whorls demonstrate the characteristic shape of the anal sinus typical of *Leucosyrinx*, and, overall, the shell morphology aligns with the variability seen within the genus.

*Leucosyrinx suratensis* resembles several species of *Leucosyrinx*, particularly *L. floraecharlottae* sp. nov. and *L. ringevali* sp. nov. However, it differs in having more pronounced spiral cords on the subsutural ramp and a stouter shell with a more rapidly constricting shell base.

**Distribution**

Type locality.

*Leucosyrinx undosa* (Schepman, 1913) comb. nov.
Fig. 33E

*Surcula undosa* Schepman, 1913: 61 (425), pl. 27 fig. 13a–b.

*Comitas undosa* – Powell 1969: 282 (23-294), pl. 227 figs 3–4.

*Paracomitas undosa* – Shuto 1970a: 170, pl. 11 figs 8–9.

**Type material**

**Holotype**

INDONESIA • Flores Sea; 7°24' S, 118°15.2' E; depth 794 m; NATURALIS, ZMA.MOLL.136841.

**Remarks**

In general shell characters, including the position of the anal sinus, the species is referable to *Leucosyrinx*. Shuto (1970a) transferred it to *Paracomitas* Powell, 1942. In our opinion this is unjustified. The genus *Paracomitas* is characterized and differentiated from *Leucosyrinx* and *Comitas* by a protoconch of 2.5 sharply carinated whorls. The protoconch is missing in the holotype of *S. undosa*, the only known specimen of the species. Therefore, pending additional data, we consider it a species of *Leucosyrinx*.

**Distribution**

Type locality.

**Doubtful species, attributed herein to Leucosyrinx**

The following species are conditionally attributed to *Leucosyrinx* pending further anatomical data and the collection of additional material. We are taking a conservative approach and will retain the species' current generic position unless there are significant reasons to transfer them.

*"Leucosyrinx caecilia"* Thiele, 1925
Fig. 34A

*Leucosyrinx caecilia* Thiele, 1925: 202 (236), pl. 24 (36) fig. 23.

*Leucosyrinx caecilia* – Powell 1969: 337 (23-401), pl. 257 fig. 2.
**Type material**

**Holotype**

TANZANIA • Dar-es-Salaam: 6°34′ S, 39°35′ E; depth 404 m; ZMB Mol 109385.

**Remarks**

The single known specimen is the juvenile holotype, with SL of 7.5 mm. The anal sinus is typical of *Leucosyrinx*, but the shoulder is accentuated by two distinct and broad spiral cords that appear wavy on poorly pronounced axial folds. This type of sculpture is not found in other species of the genus, but it is unclear whether these features are characteristics of the juvenile shell or of the species as a whole. We tentatively retain the species within *Leucosyrinx*, though with some reservations.

**Distribution**

Type locality.

**_“Leucosyrinx” canyonensis_** (Dell, 1956)

Fig. 34B

*Antimelatoma canyonensis* Dell, 1956: 142, fig. 196.

*Leucosyrinx canyonensis* – Powell 1979: 230, fig. 53: 3. — Spencer *et al.* 2011.

**Type material**

**Holotype**

NEW ZEALAND • South I., off east Otago; depth 260–350 ftm (= 475–640 m); MNZ, M.009262.

**Remarks**

The species is characterized by a small shell (SL 9.3 mm in the holotype) with strong spiral cords and a distinct crenulated shoulder carina. It is rather different from known species of *Leucosyrinx*, but in the absence of any data on anatomy, we retain it in *Leucosyrinx* with strong doubts.

**Distribution**

Type locality.

**_“Leucosyrinx” erna_** Thiele, 1925

Fig. 34C

*Leucosyrinx erna* Thiele, 1925: 201 (235), pl. 24 (36) fig. 22.

*Leucosyrinx erna* – Powell 1969: 337 (23-401), pl. 257 fig. 1.

**Type material**

**Syntypes**

TANZANIA • 3 specs; Zanzibar Channel; 5°27′ S, 39°19′ E; depth 463 m; ZMB Mol 109384.

**Remarks**

The species is known from three dead-collected and immature shells (maximal SL 7.8 mm). It is characterized by strong and very closely spaced spiral cords below shoulder that was not found in other species of *Leucosyrinx*, although somewhat similar but broader cords are also found in *L. nodulocordata* sp. nov. In the absence of any data on anatomy, we retain it in *Leucosyrinx* with strong doubts.
<figure><img src="image_36.png" /><figcaption>**Fig. 34.** **A–F.** Doubtful species of *Leucosyrinx* Dall, 1889. **A.** "*Leucosyrinx*" *caecilia* Thiele, 1925, holotype, ZMB Mol 109385, SL 7.5 mm (photo courtesy of Museum für Naturkunde). **B.** "*Leucosyrinx*" *canyonensis* (Dell, 1956), holotype, MNZ, M.009262, SL 9.3 mm (photo from the website of MNZ, https://collections.tepapa.govt.nz/object/151638). **C.** "*Leucosyrinx*" *erna* Thiele, 1925, syntype, ZMB Mol 109384, SL 7.8 mm (photo courtesy of Museum für Naturkunde). **D–F.** "*Leucosyrinx*" *sansibarica* Thiele, 1925. **D.** Original drawing (Thiele 1925: pl. 24 (36) fig. 1), ? ZMB, SL 45 mm. **E.** Syntype, ZMB Mol 60089, Gulf of Aden, SL 42.6 mm (photo courtesy of Museum für Naturkunde). **F.** Syntype, ZMB Mol 109387, Gulf of Aden, SL 34.5 mm (= *Comispira*) (photo courtesy of Museum für Naturkunde). **G–H.** Types of species excluded from *Leucosyrinx* and *Comitas* H.J. Finlay, 1926. **G.** *Rhodopetoma amycus* (Dall, 1919) comb. nov., holotype, USNM 226163, SL 21.5 mm (photo courtesy of USNM). **H.** *Burchia clionella* (Dall, 1908), syntype, USNM 123125, SL 35.2 mm (photo courtesy of USNM).</figcaption></figure>
**Distribution**

Type locality.

"Leucosyrinx" *sansibarica* Thiele, 1925
Fig. 34D–F

*Leucosyrinx sansibarica* Thiele, 1925: 181 (215), pl. 24 (36) fig. 1.

*Brachytoma griffithii* (not Gray, 1833) - von Martens 1904: 84. — Thiele 1904: 173, pl. 9 fig. 73.

*Leucosyrinx sansibarica* - Powell 1969: 340 (23-404), pl. 258 fig. 5.

**Type material**

**Syntypes**

EAST AFRICA • 2 specs; Pembakanal; 5°24' S, 39°19' E; depth 818 m; *Valdivia*, stn 246 (2 dead); ZMB?

GULF OF ADEN • 2 specs; 13°2' N, 46°41' E; depth 1469 m; *Valdivia*, stn 271; ZMB Mol 60089, ZMB Mol 109387.

**Remarks**

The species was established for *Brachytoma griffithii* sensu von Martens (1904), not Gray, 1833. Von Martens (1904) cited material from two *Valdivia* stations: station 246 (Pemba Channel, off Zanzibar) and station 271 in the Gulf of Aden. Two dead specimens were collected at the first station, while several live specimens were collected at station 271. Thiele (1904: 173, pl. 9 fig. 73) illustrated the radula of the species without indicating the exact specimen, describing a radula typical of *Comispira* with a large central formation. Von Martens (1904) proposed a variety, *gracilior*, for specimens from off Zanzibar. When Thiele (1925) renamed the species *Leucosyrinx sansibarica*, he did not designate a holotype or a type series, nor did he provide a formal description, but from the specific epithet, it can be inferred he referred to the specimens from station 246. His illustration aligns with var. *gracilior* as described by von Martens, 1904 ("Martens distinguished a var. *gracilior*, which I have illustrated in Figure 1."—my translation).

We were unable to examine the specimens from the station 246, but the specimens from the station 271 in the Gulf of Aden are not conspecific. While one specimen represents the typical *Leucosyrinx* (ZMB Mol 60089, Fig. 34E), the other, with a row of subsutural knobs, belongs to *Comispira* (ZMB Mol 109387, Fig. 34F), rather similar to *C. obtusigemmata* (see below). The specimen illustrated by Thiele (1925) (Fig. 34D) is generally similar to the specimen of *Leucosyrinx* from the Gulf of Aden (Fig. 34E), differing mainly in its slenderer shell (a variable intraspecific character in *Leucosyrinx*) and a much shallower anal sinus. It should be noted that in several of Thiele's (1925) line drawings, the illustrated anal sinus does not match the actual sinus in the same specimen. We therefore consider *L. sansibarica* as belonging to the genus, although a final decision requires examining the illustrated specimen (currently unavailable) and designating a lectotype.

**Distribution**

Tanzania to Gulf of Aden, 818–1469 m.

**Species excluded from Leucosyrinx and Comitas**

As demonstrated here, previously to the current work, there was no clear distinction between *Leucosyrinx* and *Comitas*. Numerous species of *Leucosyrinx* were erroneously attributed to *Comitas* by Powell
(1969) and are reallocated in this work. The following Indo-Pacific species were previously attributed to either *Leucosyrinx* or *Comitas*, but we are excluding them on different grounds. The species are listed in alphabetical order by their specific epithet. The species that we consider as belonging to *Comitas* are not treated here.

*Rhodopetoma amycus* (Dall, 1919) comb. nov.
Fig. 34G

*Antiplanes amycus* Dall, 1919: 36, pl. 11 fig. 5.

*Leucosyrinx kantori* McLean, 1995: 81 (replacement name for *Antiplanes amycus* Dall, 1919), invalid.

**Type material**

**Holotype**

UNITED STATES OF AMERICA • SL 21.5 mm; California, West of Monterey Bay; 36.7167° N, 122.2° W; depth 1063 m; USS *Albatross*, stn 3670; USNM 226163.

**Remarks**

Dall (1919) described two species with the epithet *amycus* – *Antiplanes amycus* (p. 36, pl. 11 fig. 5) and *Leucosyrinx amycus* (p. 5, pl. 3 fig. 7). McLean (1995) transferred *Antiplanes amycus* to *Leucosyrinx* and proposed a replacement name, *Leucosyrinx kantori*, to avoid secondary homonymy. Examination of the type specimen of *Antiplanes amycus* (USNM 226163) revealed that the anal sinus is situated in the lower part of the subsutural ramp and also occupies part of the shoulder, a feature not found in any species of *Leucosyrinx*. Therefore, this species should be excluded from *Leucosyrinx*, and according to Article 59.4 of the ICZN, the name *Antiplanes amycus* Dall, 1919 should be reinstated as valid. Based on conchological characters, we transfer the species to the genus *Rhodopetoma* Bartsch, 1944 (family Pseudomelatomidae). *Rhodopetoma* is very similar to *Antiplanes*, differing mainly in the presence of variously developed axial folds. The name *Leucosyrinx kantori* thus becomes invalid. *Leucosyrinx amycus* Dall, 1919 is considered a junior subjective synonym of *Aforia goodei* (Dall, 1890) (McLean 1971b).

**Distribution**

Type locality.

*Spergo? chuni* (von Martens, 1901) comb. nov.
Fig. 35A

*Pleurotoma* (*Pseudomata* [sic]) *chuni* von Martens, 1901: 19.

*Comitas chuni* – Powell 1969: 274 (23-286), pl. 221 fig. 1.

**Type material**

**Holotype**

INDONESIA • west coast of Sumatra; 1°48' N, 96°53' E; depth 1143 m; ZMB Moll 60091.

**Remarks**

This large species (with SL 98.9 mm in the holotype), along with *Spergo sibogae* Schepman, 1913, was attributed to *Comitas* by Powell (1969) without much discussion. He simply mentioned that "Both species fit reasonably well into the genus *Comitas*" (p. 274 (23-286)). At the same time, Powell noted that "The figure of this species, which was referred to *Pontiothauma* by von Martens (1904), suggests, by the growth lines, a rather deep turriculid-style sinus, quite foreign to that of *Pontiothauma*, which
has at most a very weak sutural sinus.” The type of *Pleurotoma chuni* is rather similar to *Spergo* Dall, 1895, particularly to *Spergo sibogae*, although its anal sinus is slightly deeper than in the mentioned species (Criscione *et al.* 2021: fig. 11f). Nevertheless, the shape of the sinus is quite different from those of *Leucosyrinx* and *Comitas*. The position of *S. sibogae* within *Spergo* was confirmed by a multilocus molecular analysis (Criscione *et al.* 2021). Based on the similarity between the shells of *Pleurotoma chuni* and *Spergo sibogae*, we reallocate the former species to *Spergo* (Raphitomidae) with some reservations.

**Distribution**

Type locality.

*Burchia clionella* (Dall, 1908)
Fig. 34H

*Leucosyrinx? clionella* Dall, 1908: 270, pl. 14 fig. 3.

*Crassispira (Burchia) clionella* – Powell 1966: 78.

"*Leucosyrinx* clionella – McLean 1971a: 120, fig. 36.

**Type material**

Syntypes?

PACIFIC OCEAN • 1 spec.; Gulf of Panama; depth 511 ftm (= 934 m); USNM 97069 • 1 spec.; Ecuador, off Manta; depth 401 ftm (= 733 m); USNM 123125.

**Remarks**

The shell differs significantly from any species of *Leucosyrinx* due to its very short siphonal canal and the anal sinus being situated in the lower part of the subsutural ramp. McLean (1971a) illustrated the species' radula, but due to the small size of the photograph, little can be discerned, except that it consists solely of duplex marginal teeth. Powell (1966) attributed the species to *Burchia* Bartsch, 1944 (Pseudomelatomidae), and we concur with this classification.

**Distribution**

Type locality.

*Lora equatorialis* Dall, 1919 (Pseudomelatomidae, genus assignment uncertain)
Fig. 35B

*Lora equatorialis* Dall, 1919: 44, pl. 13 fig. 2.

? *Leucosyrinx equatorialis* – McLean 1971a: 120, fig. 38.

**Type material**

Syntypes

PACIFIC OCEAN • 3 specs; coast of Ecuador to Patagonia; depth 122–407 ftm; USNM 97092, 97070, 697384.

**Remarks**

The small shell (13.5 mm in shell length, according to the original description) is characterized by a very short siphonal canal, strong axial ribs extending from the subsutural ramp to the siphonal canal, and an extremely shallow, barely discernible anal sinus. These features exclude the species from *Leucosyrinx*.
<figure><img src="image_37.png" /><figcaption>**Fig. 35.** Species excluded from *Leucosyrinx* Dall, 1889 and *Comitas* H.J. Finlay, 1926. *A. Spergo? chuni* (von Martens, 1901), holotype, ZMB Moll 60091, SL 98.9 mm (photo courtesy of Museum für Naturkunde).
**B. Lora equatorialis** Dall, 1919 (Pseudomelatomidae, genus assignment uncertain), syntype, USNM 97092, SL 13.5 mm (photo courtesy of USNM).
**C. Antimelatoma eremita** (Murdoch & Suter, 1906), holotype, MNZ, M.001718 (from the website of MNZ, https://collections.tepapa.govt.nz/object/151599).
**D. Leucosyrinx elsa** Thiele, 1925 (family and genus assignment uncertain), syntype, ZMB Mol 109383, SL 4.7 mm (photo courtesy of Museum für Naturkunde).
**E. Comispira erica** (Thiele, 1925) comb. nov., syntype, ZMB Mol 109382, SL 20.1 mm (photo courtesy of Museum für Naturkunde).
**F. Pleurotomella esilda** Dall, 1908 (family and genus assignment uncertain), holotype, USNM 123126, SL 22.8 mm (photo courtesy of USNM).
**G. Comispira exstructa** (von Martens, 1904) comb. nov., holotype, SL 24 mm (from von Martens 1904).
**H–I. Sibogasyrinx lancea** (Y.-C. Lee, 2001) comb. nov.
**H. Holotype, NMNS-3704001**, SL 46.9 mm (photo courtesy of Kun-Hsuan Lee).
**I. MNHN-IM-2009-13465**, Philippines (sequenced specimen). Shells not to scale.</figcaption></figure>
McLean (1971a: fig. 38) illustrated the radula of a specimen from the type series (USNM 97070), but due to the small size of the photograph, little can be discerned beyond the presence of duplex marginal teeth. This suggests that the species likely belongs to the family Pseudomelatomidae, though we are currently unable to determine its exact generic position.

**Distribution**

Type locality.

*Antimelatoma eremita* (Murdoch & Suter, 1906)

Fig. 35C

*Pleurotoma* (*Leucosyrinx*) *eremita* Murdoch & Suter, 1906: 287, pl. 22 figs 18–19.

**Type material**

**Holotype**

NEW ZEALAND • off Great Barrier I., North I.; depth 110 ftm (= 201 m); MNZ, M.001718.

**Remarks**

In its shell characters this small species (SL of the holotype 5.8 mm) is very different from *Leucosyrinx*, but fits well the morphology of the genus *Antimelatoma* Powell, 1942 (family Psudomelatomidae). It is identified as *Antimelatoma* in the collections of Museum of New Zealand Te Papa Tongarewa and we follow here this generic assignment.

**Distribution**

Type locality.

*Leucosyrinx elsa* Thiele, 1925 (family and genus assignment uncertain)

Fig. 35D

*Leucosyrinx elsa* Thiele, 1925: 201(235), pl. 24(36) fig. 21.

*Leucosyrinx elsa* – Powell 1969: 337 (23-401), pl. 257 fig. 3.

**Type material**

**Syntypes**

TANZANIA • 1 spec.; Zanzibar Channel; 5°27′ S, 39°18′ E; depth 463 m; Valdivia, stn 245; ZMB Mol 109383 • 25 specs; Dar Es Salaam; Valdivia, stn 242; ZMB Mol 109383.

**Remarks**

The species is known only from numerous empty juvenile shells (SL up to 5.8 mm) from two stations off Tanzania. The spiral sculpture on the last whorl is dominated by several strong cords below the shoulder crossing axial folds extending in some specimens to the shell base and thus isolating two or sometimes three rows of strong nodules (more pronounced than in the figured herein syntype). This type of sculpture is not found in any species of *Leucosyrinx*, and we exclude the species from the genus. Current taxonomic position is unknown.

**Distribution**

East Africa, Tanzania, 463 m.
*Comispira erica* (Thiele, 1925) comb. nov.
Fig. 35E

*Leucosyrinx erica* Thiele, 1925: 236, pl. 36 (24) fig. 25.

*Comitas erica* – Powell 1969: 284 (23-296), pl. 226 fig. 2. — Sysoev 1996: 8, fig. 41.

**Type material**

**Syntypes**

SUMATRA • 3 specs; off Siberut I., 0°39' S, 98°52' E; depth 750 m; ZMB Mol 109382.

**Remarks**

The type series consists of 3 shells, one complete (SL 20.1 mm), one juvenile and one broken.

The species is characterized by a subsutural row of rounded knobs. This is not found in any species of *Leucosyrinx*, but on the contrary present in all species of *Sibogasyrinx* and *Comispira*. Based on the spiral sculpture pattern we conditionally attribute the species to *Comispira*.

**Distribution**

Zanzibar, Maldive Is. and Sumatra, 750–797 m.

*Pleurotomella esilda* Dall, 1908 (family and genus assignment uncertain)
Fig. 35F

*Pleurotomella* (*Pleurotomella*) *esilda* Dall, 1908: 282.

*Leucosyrinx esilda* – McLean 1971b: sp. 1668, with query.

**Type material**

**Holotype**

PACIFIC OCEAN • Gulf of Panama; depth 730 ftm (= 1335 m); USNM 123126.

**Remarks**

The species is based on a single, heavily broken, dead-collected shell (22.8 mm in shell length). It differs significantly from species of *Leucosyrinx* as defined here, exhibiting a very short siphonal canal, strong and long axial ribs extending to the poorly defined subsutural ramp, and an anal sinus situated close to the shoulder. On these grounds, we exclude the species from *Leucosyrinx*, but we are currently unable to determine its generic position.

**Distribution**

Type locality.

*Comispira exstructa* (von Martens, 1904) comb. nov.
Fig. 35G

*Surcula exstructa* von Martens, 1904: 81, pl. 1 fig. 4.

*Surcula exstructa* – Thiele 1925: 181(215), pl. 23(35) fig. 21.

*Comitas exstructa* – Powell 1969: 283 (23-295), pl. 226 fig. 1
**Type material**

**Holotype**

INDIAN OCEAN • Nicobar Is.; 7°48′ N, 93°07′ E; depth 805 m; whereabouts unknown.

**Remarks**

This species is based on a single strongly damaged holotype (SL 24 mm). The original drawing and the details of the sculpture provided by Thiele (1925) show a subsutural row of rounded knobs. These are not found in any species of *Leucosyrinx*, but are, conversely, present in all species of *Sibogasyrinx* and *Comispira*. Based on the broadly-spaced and rather strong spiral cords, we attribute the species to *Comispira*.

**Distribution**

Type locality.

*Sibogasyrinx lancea* (Y.-C. Lee, 2001) comb. nov.
Fig. 35H-I

*Leucosyrinx lancea* Y.-C. Lee, 2001: 8, fig. 2a-d.

**Type material**

**Holotype**

TAIWAN • off Pratas I.; depth 430–610 m; dredged by shrimp trawlers; NMNS-3704001.

**Material examined (sequenced)**

PHILIPPINES • 1 lv; Luzon I.; 15°53′ N, 121°54′ E; depth 518–538 m; AURORA 2007, stn CP2750; MNHN-IM-2009-13465.

**Remarks**

The species is characterized by a subsutural row of rounded knobs. This is not found in any species of *Leucosyrinx*, but is, conversely, present in all species of *Sibogasyrinx* and *Comispira*. Moreover, a very similar specimen (MNHN-IM-2009-13465 – Fig. 35E), collected off Luzon, Philippines, at similar depths (518–538 m) was recently sequenced and a partial *cox1* sequence confidently places it in *Sibogasyrinx*. Therefore, we transfer it to *Sibogasyrinx*.

**Distribution**

Taiwan to Philippines, 430–518 m.

*Comispira obtusigemmata* (Schepman, 1913) comb. nov.
Fig. 36A

*Surcula obtusigemmata* Schepman, 1913: 60(424), pl. 27 fig. 12a-b.

*Comitas obtusigemmata* – Powell 1969: 284 (23-296), pl. 227 figs 1–2. — Sysoev 1997: 347.

**Type material**

**Syntypes**

INDONESIA • 1 spec.; Makassar Strait; 4°22.1′ S, 118°16.9′ E; depth 2029 m; Siboga Expedition stn 76; NATURALIS, ZMA.MOLL.137985 • 1 spec.; channel between Makjan and Halmahera; 0°23.8′ N, 127°29′ E; depth 472 m; Siboga Expedition stn 137; NATURALIS, ZMA.MOLL.137983 • 1 spec.;
Arafura Sea; 5°46.7' S, 139°00' E; depth 1788 m; Siboga Expedition stn 271; NATURALIS, ZMA.
MOLL.137984.

**Remarks**

The species is characterized by a subsutural row of rounded knobs. This is not found in any species of *Leucosyrinx* or *Comitas*, but on the contrary present in all species of *Sibogasyrinx* and *Comispira*. In shell shape and sculpture the species is quite similar to *Comispira mai* (Li & Li, 2008) (Kantor *et al.* 2018: fig. 2a-c), differing in a slightly shorter shell and larger knobs on the shell periphery. Therefore, we transfer *Surcula obtusigemmata* to *Comispira*.

Conchologically, the species is very similar to *Comispira subsuturalis* (von Martens, 1901) and both species can be conspecific. Presently, we recognize both species as valid due to significant distance between collecting sites – East Africa for *C. subsuturalis* and Indonesia for *C. obtusigemmata*.

Schepman (1913) cited erroneously the longitude of stn 76 as 180°16.9' E. The coordinates provided here corresponding to the Macassar Strait were taken from Tydeman (1902).

**Distribution**

Indonesia, 472–1788 m.

*Mangelia opulenta* Thiele, 1925

*Mangelia opulenta* Thiele, 1925: 306(340), pl. 28(40) fig. 4.

*Comitas opulenta* – Bozzetti 1993: 1.

**Type locality**

Padang, Sumatra.

**Remarks**

The species described and illustrated by Thiele (1925) definitely belongs to Mangeliidae P. Fischer, 1883.
Bozzetti (1993) without any discussion and undoubtedly erroneously attributed the species to *Comitas*.
Therefore, we reinstate herein the original binomen of the species, although the generic position of the
species requires clarification

**Distribution**

Type locality.

*Sibogasyrinx pikei* (Dell, 1963) comb. nov.
Fig. 36B

*Waitara pikei* Dell, 1963: 215, textfigs 3–4.

*Leucosyrinx pikei* – Powell 1969: 339(23-403), pl. 258 figs 3–4; 1979: 230, pl. 47 fig. 8.

**Type material**

**Holotype**

NEW ZEALAND • 18 miles N, 30° E of Poor Knights Is.; depth 256–267 fathoms (= 468–488 m);
20 Nov. 1962; MNZ, M.016273.
<figure><img src="image_38.png" /><figcaption>**Fig. 36.** Species excluded from *Leucosyrinx* Dall, 1889 and *Comitas* H.J. Finlay, 1926. **A. Comispira obtusigemmata** (Schepman, 1913) comb. nov., syntype, NATURALIS, ZMA.MOLL.137984, SL 22.5 mm (photo courtesy of K. Hasegawa). **B. Sibogasyrinx pikei** (Dell, 1963) comb. nov., holotype, MNZ, M.016273, SL 35.5 mm (from the website of MNZ, https://collections.tepapa.govt.nz/object/150983). **C. Comispira saudesae** (Cossigniani, 2018) comb. nov., paratype, SL 30, 28.9 mm, collection of Jean Pierre Vezzaro (photos courtesy of T. Cossigniani). **D. Comispira saudesae**, MNHN-IM-2009-18998, Philippines, SL 22.8 mm (sequenced specimen). **E–F. Comispira subsuturalis** (von Martens, 1901) comb. nov. **E. Syntype**, SL 16.1 mm. **F. Syntype**, SL 22.1 mm (photo courtesy of Museum für Naturkunde). **G. Sibogasyrinx suluensis** (Powell, 1969) comb. nov., holotype, USNM 238399, SL 21.0 mm (photo courtesy of USNM). **H. Sibogasyrinx variabilis** (Schepman, 1913) comb. nov., lectotype, NATURALIS, ZMA.MOLL.136887, SL 18.5 mm (photo courtesy of K. Hasegawa). Shells not to scale.</figcaption></figure>
**Remarks**

The species was originally described based on two specimens, and no new specimens have been reported in the literature since its original description. In 1969, Powell transferred the species to the genus *Leucosyrinx*. However, the shell is characterized by the presence of a subsutural row of weak but distinct nodules – a feature never found in *Leucosyrinx*, but present in *Sibogasyrinx* and *Comispira*. In its slender shell with relatively weak uniform spiral sculpture the species is more similar to *Sibogasyrinx*. Therefore, we currently attribute the species, with some reservation, to *Sibogasyrinx*; this needs confirmation through examination of the radula or molecular data.

**Distribution**

Type locality.

*Comispira saudesae* (Cossigniani, 2018) comb. nov.
Fig. 36C–D

*Comitas saudesae* Cossigniani, 2018: 30.

**Type material**

**Holotype**

TAIWAN • Nord-East Taiwan; depth 300–500 m; MMM.

**Material examined (sequenced)**

PHILIPPINES • 2 lv; Luzon I.; 15°20′ N, 121°37′ E; depth 593–600 m; AURORA 2007, stn CP2729; MNHN-IM-2009-18997, MNHN-IM-2009-18998.

**Material examined (not sequenced)**

PHILIPPINES • 1 lv; off Panglao I., 9°36′ N, 123°42′ E; depth 609–673 m; PANGLAO 2005, stn CP2396; MNHN-IM-2009-13387

**Remarks**

The species is characterized by a subsutural row of rounded knobs, which are more prominent in the paratypes. This feature is not found in any species of *Leucosyrinx* or *Comitas*, but is consistently present in all species of *Sibogasyrinx* and *Comispira*. Our specimens closely resemble the type series, particularly the paratypes. Although unpublished, molecular data place the species within *Comispira*. Our findings extend the known range of the species from Taiwan to the Philippines.

**Distribution**

Philippines to Taiwan, 300–600 m.

*Comispira subsuturalis* (von Martens, 1901) comb. nov.
Fig. 36E–F

*Pleurotoma (Brachytoma) subsuturalis* von Martens, 1901: 16.

*Brachytoma subsuturalis* – von Martens 1904: 85, pl. 1 fig. 7.

*Comitas subsuturalis* – Powell 1969: 285 (23-297), pl. 226 figs 3–4. — Sysoev 1996: 7, figs 31–40. — Hasegawa 2005: 169, fig. 11e-f.
**Type material**

**Syntypes**

INDIAN OCEAN • 2 specs; East Africa; 1°49' N, 45°29' E; depth 1134 m; ZMB Mol 60088.

**Remarks**

Powell (1966: fig. 52) illustrated the radula of a specimen from the John Murray expedition, which features a large central formation typical of Cochlespiridae, but absent in *Comitas* and *Leucosyrinx*. The shell of this species has a row of subsutural nodules, a feature not found in any species of *Leucosyrinx* or *Comitas*, but present in all species of *Sibogasyrinx* and *Comispira*. The shell shape and sculpture closely resemble those of *Comispira*, leading us to transfer the species to that genus.

**Distribution**

This species is very broadly distributed, ranging from East Africa through the Indian Ocean to Japan, at depths of 494–1789 meters. This exceptionally wide distribution and high variability (Sysoev 1996) may indicate that we are dealing with a complex of species.

*Sibogasyrinx suluensis* (Powell, 1969) comb. nov.
Fig. 36G

*Comitas suluensis* Powell, 1969: 280 (23-292), pl. 223 fig. 7

**Type material**

**Holotype**

Philippines • Sulu Archipelago, off Cagayan I.; depth 508 ftm (= 929 m); USNM 238399.

**Remarks**

The shell of this species has a row of subsutural nodules, a feature not found in any species of *Leucosyrinx* or *Comitas*, but present in all species of *Sibogasyrinx* and *Comispira*. In shell outline the species is more similar to *Sibogasyrinx* spp. than to any *Comispira*, therefore we allocate it to *Sibogasyrinx*.

**Distribution**

Type locality.

*Turris saldanhae* Barnard, 1958 (Pseudomelatomidae, genus assignment uncertain)

*Turris saldanhae* Barnard, 1958: 109, figs 3f, 7.

*Comitas saldanhae* – Powell 1966: 15, fig. b7; 1969: 267 (23-279), pl. 205 fig. 1, with query. — Nolf 2011: 1–2, pls 1–2.

**Type material**

**Holotype**

SOUTH AFRICA • Saldanha Bay, off Baboon Point; depth 31 ftm (= 57 m); SAM A1738.

**Remarks**

The shell of the species possesses an anal sinus, which occupies part of the subsutural ramp, similar to species of *Comitas*. Nervertheless, the radula, as illustrated by Barnard (1958: fig. 3f), consists of duplex marginal teeth, with the accessory limb of the marginal tooth inserted into a rather deep and broad socket on the major limb. This tooth structure is very different from the radulae of *Comitas* that have been
examined (Fig. 3F). Although we cannot determine the exact generic position of the species, the radula type suggests it belongs to the family Pseudomelatomidae.

**Distribution**

South Africa, Namibia, 55–1280 m.

*Sibogasyrinx variabilis* (Schepman, 1913) comb. nov.
Fig. 36H

*Surcula variabilis* Schepman, 1913 (part.): 61(425), pl. 28 fig. 1a.

*Comitas variabilis* – Powell 1969: 281 (23-293), pl. 224 fig. 1.

*Schepmania variabilis* – Shuto 1970b: 38, pl. 3 figs 1–3.

*Shutonia variabilis* – Van der Bijl 1993: 146 (new generic name for *Schepmania* Shuto, 1970, non *Schepmania* Haas, 1913).

**Type material**

**Lectotype**

INDONESIA • Ceram Sea; 2°40′ S, 128°37.5′ E; depth 835 m; ZMA 136887.

**Remarks**

The type series consisted of 12 specimens collected from the same station. Later, Shuto (1970b) observed that the series actually included three different species and described two of them based on the syntypes, *Makiyamaia sibogae* Shuto, 1970, and *Lucerapex schepmani* Shuto, 1970. Shuto applied the name *Schepmania* gen. nov. *variabilis* to three specimens. However, the genus was later renamed as *Shutonia* due to homonymy (van der Bijl 1993).

Examination of the photograph of the largest specimen (illustrated by Schepman 1913: pl. 28 fig. 1a) revealed that it possesses a subsutural row of nodules, more prominent on the upper whorls, which is characteristic of *Sibogasyrinx* and *Comispira* but not of other genera of Conoidea. Therefore, we transfer the species to *Sibogasyrinx*, rendering *Shutonia* a junior synonym.

**Distribution**

Type locality.

**Discussion**

**Diversity of *Leucosyrinx***

The molecular phylogenetic analysis revealed the existence of 62 SSHs in our material collected from the Indo-Pacific. We were able to assign existing names to 12 of them. The remaining 50 SSHs represent new species, of which we have described 24, leaving 26 unnamed (*Leucosyrinx* sp. 1 to *Leucosyrinx* sp. 26). We did not name these 26 SSHs primarily because 20 were represented by a singleton, and the others by a very limited number of specimens (two specimens for four SSHs and three specimens for two SSHs). The SSHs represented by two or more specimens were either morphologically indistinguishable from other species, or comprised heterogeneous material, or lacked well-preserved specimens necessary for species descriptions.

We refined morphological characteristics of *Leucosyrinx*, and were able to confidently attribute 18 previously named Pacific species to that genus, and four more species were attributed to the genus conditionally. This brings the total number of species of *Leucosyrinx* in the Indo-Pacific to 84, 58 of
which are named. Additionally, there are several species of *Leucosyrinx* in the Atlantic, including the type
species of the genus, *L. verrillii*. The total number of described and accepted species positions the genus
as the third most diverse within the family Pseudomelatomidae, following *Crassispira* Swainson, 1840
(with 118 accepted recent species according to MolluscaBase 2024) and *Inquisitor* Hedley, 1918 (with
74 species). When considering the total number of SSHs (86, including Atlantic species), *Leucosyrinx*
ranks as the second most species-rich genus. Additionally, the monophyly of *Crassispira* has not been
tested with molecular data; the genus is morphologically very heterogeneous, and it is possible that, in
its current scope, it is paraphyletic. The next speciouse genus is *Otitoma* Jousseaume, 1898 with only
33 accepted Recent species.

Eighteen species that were previously attributed to *Leucosyrinx* or *Comitas* before this study have been reassigned to other genera based on refined morphological characteristics of the shell.

Species of *Leucosyrinx* are generally rare. Among the material we sequenced, 22 SSHs are represented by a single specimen, an additional 14 SSHs by two specimens, and only four SSHs by more than 10 specimens. An exception is *Leucosyrinx bolognai*, which is represented in our material by 45 specimens, though only three were recently collected and successfully sequenced. Similarly, 10 out of the 18 previously described species, absent in our material, are known only from the holotype, while the remaining species are represented by 2–3 specimens.

This rarity can be partially explained by the relatively deep-water habitat of *Leucosyrinx*, confined to
the upper bathyal zone, making material collection difficult. The shallowest depth recorded is 195 m
(*L. breviplicata*), while the deepest is 3014 m (*L. exulans*). When considering the shallower depths of the
range for each species, 18 species were collected at depths shallower than 500 m, 33 at depths between
500–1000 m, and 8 at depths greater than 1000 m.

Morphological variability and application of the names

In general, *Leucosyrinx* is characterized by a shell that is highly variable in shape and size, ranging
from small (adult size less than 10 mm) to very large, up to 90 mm in length. The shell varies from
narrow fusiform (Fig. 21I–O) to broadly oval (Fig. 24). Apart from size and outline, the shell of
*Leucosyrinx* is relatively poor in diagnostic features. A distinct color pattern is absent, and with few
exceptions, the spiral sculpture is very similar among species, consisting of rather uniform, weak spiral
cords. Exceptions include *L. breviplicata*, with its broadly-spaced and relatively strong spiral cords
(Fig. 26), and *L. nodulocordata* sp. nov., which has fewer spiral cords below the shoulder, forming
nodules (Fig. 28H–L). The intraspecific variability within molecularly defined species can be high
(e.g., in *L. breviplicata* – Fig. 26) and, in some cases, exceeds interspecific variability. For example,
*Leucosyrinx* sp. 26 and *Leucosyrinx* sp. 7 (Fig. 27C–H) are very similar to *L. breviplicata*, with no
clear morphological differences from the latter species. This situation is exacerbated by the rarity of the
majority of species, making it impossible to evaluate their variability comprehensively.

Molecular analyses, in addition to delimiting PSHs and inferring phylogenetic relationships, often
proves indispensable for post hoc refinement and correction of morphological diagnoses in an integrative
taxonomy approach. This enables the reassessment of the taxonomic position of even non-sequenced
specimens. In this study, by analyzing the morphology of a large number of sequenced species of
*Leucosyrinx* and comparing them with sequenced species of similar genera, such as *Sibogasyrinx*,
*Comispira*, and *Comitas*, we were able to identify taxonomically important characters and refine the
diagnosis of *Leucosyrinx*. For instance, the shape and position of the anal sinus, which spans across the
entire subsutural ramp but does not extend below the shoulder, distinguishes *Leucosyrinx* from *Comitas*.
Although Powell (1966, 1969) recognized the importance of the anal sinus shape, he did not consistently
use this character, leading to the erroneous transfer of many species of *Leucosyrinx* to *Comitas*. Another
example is the subsutural row of knobs, present in all species of *Sibogasyrinx* and *Comispira* but absent in *Leucosyrinx* and *Comitas*. Similarly, Powell (1969) recognized this character's importance and even established a separate "subsuturally gemmate series" of species of *Comitas* but clearly underestimated its taxonomic significance. Correspondingly, when describing *Leucosyrinx* (*Sibogasyrinx*), he mentioned the presence of "comma-like subsutural crenulations" in the type species, *S. pyramidalis* (Schepman, 1913), but also attributed to the same subgenus a second species, *L. archibenthalis*, which lacks subsutural knobs and is here attributed to *Leucosyrinx* proper. This misclassification was followed by other researchers, such as Sysoev (1996), who attributed species with subsutural knobs to *Comitas*.

All but two previously described species of *Leucosyrinx* discussed here were described based solely on shell characteristics. Consequently, applying available names to SSHs can only be done through shell comparisons. However, we have demonstrated that, in many cases, intraspecific variability can exceed interspecific differences. Additionally, many species of *Leucosyrinx/Comitas* were described from remote areas that are currently inaccessible due to legal restrictions (e.g., Andaman Is., Sri Lanka, and Gulf of Oman). Therefore, sequencing specimens from the type localities is hardly achievable. Even when material is collected near the type locality, more than one species may be present, complicating the application of a name. This is evident in the conchologically similar species from the Philippines and adjacent areas, such as *L. luzonica*, *L. quinetae*, and *Leucosyrinx* sp. 19 (see remarks on the description of *L. luzonica*).

As a result of the above considerations, in some cases, existing names can only be conditionally applied to molecularly defined SSHs. Nevertheless, we have adopted a conservative approach, attempting to apply as many existing names as possible to the defined SSHs. We consider this a necessary measure to avoid creating potential synonyms. In the future, when extracting DNA from holotype shells becomes routine (Walton *et al.* 2023), any potential mistake can be easily corrected. The situation with *Leucosyrinx* once again emphasizes the necessity of molecular data to support description of new species in taxonomically challenging groups. Even species that seem distinct at the moment may later prove to be a part of a group of cryptic species, as has been demonstrated multiple times in different groups of Conoidea (e.g., in the genera *Gemmuloborsonia* Shuto, 1989 and *Lophiotoma* Casey, 1904 – Puillandre *et al.* 2010, 2017).

## Radular morphology

The radula was examined in 40 sequenced species of *Leucosyrinx*. With the absence of a central formation, the radular morphology is fairly uniform within the genus. The variability in the shape of the marginal teeth primarily concerns their slenderness (i.e., the ratio between the maximal tooth width and its length) and the degree of curvature of the major limb of the tooth. Currently, we cannot use these characters for morphological diagnostics of the species, as they are difficult to quantify – the visible tooth shape significantly depends on the angle at which it is observed. A more variable characteristic is the relative tooth length, which is the ratio between tooth length and aperture length. This ratio varies from 1.6–1.8% in *L. farhatorum* to 6.6% in *L. luzonica*. We did not observe a correlation between relative tooth length and shell length, as both the shortest and longest teeth were recorded in species of similar size (with maximum shell lengths of 42.7 mm and 42 mm, respectively). It is possible that differences in tooth length may reflect differences in diet, although this cannot be confirmed at the moment, as the diet of species of *Leucosyrinx* remains unknown.

While radular morphology cannot currently be used for species discrimination, it remains an invaluable tool when combined with certain shell characteristics, such as the shape of the anal sinus and the pattern of the axial sculpture, for distinguishing *Leucosyrinx* from conchologically similar related genera like *Comitas*, *Antarctospira*, and *Sibogasyrinx*.
<table><caption>**Table 1.** The recorded absolute and relative species richness of *Leucosyrinx* Dall, 1889 in different studied areas.</caption><thead><tr><td>Region</td><td>No. of spp</td><td>No. of hauls</td><td>No. of hauls/no. spp.</td></tr></thead><tbody><tr><td>Philippines</td><td>10</td><td>148</td><td>14.8</td></tr><tr><td>PNG–Solomon Islands</td><td>30</td><td>684</td><td>22.8</td></tr><tr><td>Madagascar, Mozambique</td><td>7</td><td>176</td><td>25.1</td></tr><tr><td>South China Sea</td><td>2</td><td>54</td><td>27</td></tr><tr><td>Walters Shoal</td><td>1</td><td>44</td><td>44</td></tr><tr><td>Vanuatu</td><td>3</td><td>144</td><td>48</td></tr><tr><td>New Caledonia–Coral Sea</td><td>14</td><td>768</td><td>54.8</td></tr><tr><td>Society Islands</td><td>2</td><td>204</td><td>102</td></tr></tbody></table>

## Distribution patterns

*Leucosyrinx* is a broadly distributed genus found in both the Indo-Pacific and Atlantic Oceans. In the Atlantic, molecular data confirm its distribution, ranging from North Carolina (*L. verrillii*) to Argentina (*L. argentina* Sánchez & Pastorino, 2024). In the Indo-Pacific, the genus spans both oceans, from the Galapagos Is. in the east, through the Eastern, Central, and Western Indo-Pacific, to Mozambique and Madagascar in the west, southern Australia and Tasmania in the south, and Japan in the north. Our review is based almost exclusively on material collected during oceanographic cruises organized by MNHN, and therefore largely reflects the museum's current efforts (molecular-grade deep-water material of *Leucosyrinx* was first collected in 2005 during the PANGLAO 2005 expedition in the Philippines) rather than the actual distribution pattern of the genus.

The number of recorded species (SSH) varies greatly by region, from 30 in Papua New Guinea and the Solomon Is. to a single species in the Walters Shoal in the Indian Ocean (Table 1). To determine whether these numbers reflect the actual diversity of the genus in each region or are influenced by sampling activities, we counted the total number of bottom operations during cruises that yielded specimens of *Leucosyrinx* for each selected region in the depth range where specimens of *Leucosyrinx* were recorded. We then divided the number of operations by the number of recorded species. A lower value indicates higher recorded diversity. Interestingly, the Philippines, with only 10 recorded species, is by far the richest region (Table 1), with approximately 15 operations per recorded species, while Papua New Guinea and the Solomon Is., with 30 recorded species, rank as the second richest region (22.8 operations per recorded species). New Caledonia and the Coral Sea, with 14 recorded species, are penultimate among the analyzed regions (54.8 operations per species).

This analysis is preliminary, as many regions of the Indo-Pacific have not been recently sampled, and no molecular-grade material is available for these areas.

In general, the observed distribution of species of *Leucosyrinx*, as confirmed by molecular data, is characterized by rather narrow ranges. Typically, a species inhabits a single archipelago, with the exception of Papua New Guinea, the Bismarck Archipelago, and the Solomon Is., which share many common species. Only four species extend their range from Papua New Guinea and the Solomon Is. to the Philippines (*L. schepmani* sp. nov., *L. margaritae*, *L. nodulocordata* sp. nov., *L. archibenthalis*), two to New Caledonia (*L. bourgeoisae* sp. nov., *L. modicae* sp. nov.) and one species is distributed from the Philippines to the South China Sea (*L. luzonica*). Finally, one species, represented by only two specimens,
has been recorded in both Madagascar and Papua New Guinea (*Leucosyrinx* sp. 18). We suspect broader
distribution in some previously described species, but it has not yet been confirmed by molecular data.
Generally, the small paucispiral protoconch, with less than two whorls in all species of *Leucosyrinx*
examined in this respect, suggests direct development and thus limited dispersal abilities. However, it
is also possible that the narrow ranges observed are to some extent an artifact of the limited material
at our disposal. However, it is noticeable that the overall pattern of species distributions and rarity in
*Leucosyrinx* is in stark contrast with the very broad distribution ranges demonstrated in other conoidean
lineages, the turrid genus *Cryptogemma* Dall, 1918 (Zaharias *et al.* 2020), and raphitomid genera, such
as *Theta* A.H. Clarke, 1959 (Sánchez & Pastorino 2020; Criscione *et al.* 2021). Nevertheless it should be
emphasized that the mentioned genera are characterized by planctotrophic larvae and, correspondingly,
higher dispersal abilities. The very broad geographic distribution of *Leucosyrinx* in combination with
i) narrow species distribution ranges ii) general rarity, indicate that we may be still very far from
exhaustive sampling of the *Leucosyrinx* worldwide diversity. This rarity pattern establishes the genus
*Leucosyrinx* as a major reservoir of undescribed deep-sea diversity at the genus level. Further seafloor
sampling, especially in the currently weakly covered areas are likely to continue discover new species,
for many years from now.

Acknowledgements

Specimens were obtained during research cruises and expeditions organized by the MNHN and ProNatura
International as part of the Our Planet Reviewed program, and by the MNHN and the Institut de Recherche
pour le Développement as part of the Tropical Deep-Sea Benthos program (NanHai 2014 and ZhongSha
2015 in the South China Sea, PANGLAO 2005 and AURORA 2007 in the Philippines, SALOMON 2
(https://doi.org/10.17600/4100090) and SALOMON BOA3 (https://doi.org/10.17600/7100070)
in the Solomons, BIOPAPUA (https://doi.org/10.17600/10100040), KAVIENG 2014 (https://doi.
org/10.17600/14004400), MADEEP (https://doi.org/10.17600/14004000) and PAPUA NIugini
(https://doi.org/10.17600/18000841) in Papua New Guinea, BOA1 (https://doi.org/10.17600/5100060)
and SANTO 2006 in Vanuatu, CONCALIS (https://doi.org/10.17600/8100010), EBISCO (https://doi.
org/10.17600/5100080), KANACONO (https://doi.org/10.17600/16003900), KANADEEP (https://
doi.org/10.17600/17003800) and TERRASSES (https://doi.org/10.17600/8100100) in New Caledonia,
TARASOC (https://doi.org/10.17600/9100040) in French Polynesia, ATIMO VATAE (https://doi.
org/10.17600/10110040) and MIRIKY in Madagascar, and MD208 (Walters Shoal, https://doi.
org/10.17600/17002700) in southern Indian Ocean), and we are grateful to numerous cruise leaders and
co-PIs: Wei-Jen Chen, Philippe Bouchet, Marivene Manuel Santos, Laure Corbari, Stephane Hourdez,
Ludivina Labe, Peter Kee Lin Ng, Karine Olu-Le Roy, Bertrand Richer de Forges and Sarah Samadi
(more information can be found at https://expeditions.mnhn.fr/). These expeditions operated under the
regulations then in force in the countries in question and satisfy the conditions set by the Nagoya Protocol
for access to genetic resources. We thank Barbara Buge for her help in curating the specimens and Mark
Phuong and Jawad Abdelkrim for their help with bioinformatics scripts. We are very grateful for the help
with the images of type specimens, particularly to Kazunori Hasegawa (National Museum of Nature &
Science, Japan), Andreia Salvador and Aimee McArdle (NHMUK, London), Roberto Arrovini and
Tiziano Cosignani (Italy), Hsin Lee and Kun-Hsuan Lee (National Museum of Natural Science, Taiwan),
Corey Whisson (WAM, Perth), Ellen Strong and Yolanda Villacampa (USNM, Washington DC),
Thomas von Rintelen, Christine Zorn and Pia Nitschke (Museum für Naturkunde). Our sincere thanks
go to the anonymous reviewers and the editor, Prof. Thierry Backeljau, for their numerous corrections
and suggestions, which greatly improved the manuscript. This study was conducted using Joint Usage
Center “Instrumental methods in ecology” at the IEE RAS. We thank R.M. Hatsaeva, S. Kolchev,
D. Zaikin, and A. Neretina for their friendly and helpful assistance with the SEM facilities. This work
was supported by the European Research Council (ERC) under the European Union’s Horizon 2020
research and innovation programme (grant agreement no. 865101) to N.P.
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Manuscript received: 11 September 2024

Manuscript accepted: 24 January 2025

Published on: 27 June 2025

Topic editor: Magalie Castelin

Section editor: Thierry Backeljau

Desk editor: Pepe Fernández

Printed versions of all papers are deposited in the libraries of four of the institutes that are members of the *EJT* consortium: Muséum national d'Histoire naturelle, Paris, France; Meise Botanic Garden, Belgium; Royal Museum for Central Africa, Tervuren, Belgium; Royal Belgian Institute of Natural Sciences, Brussels, Belgium. The other members of the consortium are: Natural History Museum of Denmark, Copenhagen, Denmark; Naturalis Biodiversity Center, Leiden, the Netherlands; Museo Nacional de Ciencias Naturales-CSIC, Madrid, Spain; Leibniz Institute for the Analysis of Biodiversity Change, Bonn – Hamburg, Germany; National Museum of the Czech Republic, Prague, Czech Republic; The Steinhardt Museum of Natural History, Tel Aviv, Israël.

**Supplementary files**

**Suppl. file 1.** Bayesian phylogenetic tree obtained with the *cox1* dataset. Posterior probabilities (> 0.80) are shown for each node. https://doi.org/10.5852/ejt.2025.999.2945.13295

**Suppl. file 2.** ASAP partitions of sequenced specimens, the best partition (rank 1) is second from the right. https://doi.org/10.5852/ejt.2025.999.2945.13297

**Suppl. file 3.** List of examined material included in molecular phylogenetic analysis. GB = GenBank.
https://doi.org/10.5852/ejt.2025.999.2945.13299