Janthina globosa
Creators: name: Beu, Alan G.
Publisher: name: Zenodo
Year: 2017
Subjects: Biodiversity
Taxonomy
Animalia
Mollusca
Gastropoda
Janthinidae
Janthina
Janthina globosa

description: Janthina globosa (Swainson, 1822)
Figs 2G–J, 30–31
Helix janthina Linnaeus. – Linnaeus, 1764: 670 (misidentification; see Laursen, 1953: 17, pl. 1, fig. 2).
Ianthina globosa Swainson, 1822: pl. 85, central fig. (Jan 1822); H. Adams & A. Adams, 1854: 87; Reeve, 1858: pl. 4, figs 18a–b; G. B. Sowerby II, 1882: 51, pl. 444, figs 16, 18; Tryon, 1887: 37, pl. 10, figs 11–14; Martens, 1904: 143; Iredale, 1910: 71; Oliver, 1915: 525; Morton, 1954: 167, fig. 1d (in part misidentified, = J. pallida Thompson).
Janthina prolongata Blainville, 1822: 155 (Aug 1822); Payraudeau, 1826: 121, pl. 6, fig. 1; Deshayes, 1843: 5; Küster, 1868: 6, pl. 1, fig. 6; Bennett, 1966: 41, pl. 9, fig. 1, pl. 10, fig. 1; Morton & Miller, 1968: 472; Keen, 1971: 442, fig. 689; Kilburn & Rippey, 1982: 79, fig. 38, pl. 11, fig. 17; Bosch et al., 1995: 111, fig. 441; Okano & Wada, 2012: 58, fig. 2.
Ianthina nitens Menke, 1828: 84; Reeve, 1858: pl. 4, figs 16a–b; Benson, 1860: 409; G. B. Sowerby II, 1882: 51, pl. 444, fig. 21.
Ianthina elongata Blainville. – Maravigna, 1838: 63 (incorrect subsequent spelling of I. prolongata); Aradas & Benoit, 1874: 148.
Janthina rosea Anton, 1838: 50.
Janthina patula Philippi, 1844: 224, pl. 28, fig. 1.
Ianthina decollata Carpenter, 1857: 187; Reeve, 1858: pl. 4, figs 19a–b; Angas, 1867: 230; Keen, 1968: 410, pl. 59, figs 78a–c.
Ianthina iricolor Reeve, 1858: pl. 5, figs 23a–b; G. B. Sowerby II, 1882: 51, pl. 444, fig. 18.
Ianthina communis Lamarck. – Chenu, 1859: 118, figs 517–518 (misidentification).
Janthina (Janthina) nitens Menke. – Mörch, 1860: 280; Priolo, 1959: 183.
Janthina (Janthina) nitens var. atlantica Mörch, 1860: 280.
Janthina (Janthina) globosa Swainson. – Mörch, 1860: 280.
Janthina (Janthina) iricolor Reeve. – Mörch, 1860: 281.
Janthina (Janthina) decollata Carpenter. – Mörch, 1860: 281.
Janthina iricolor Reeve. – Mörch, 1860: 281; Hutton, 1880: 71; Yen, 1942: 219, pl. 20, fig. 123 (syntypes).
Janthina nitens Menke. – Küster, 1868: 7, pl. 1, figs 9–13; Monterosato, 1878: 95; Monterosato, 1884: 104; Bucquoy et al., 1886: 434, text-fig. 6; Thiele, 1929: 225; Priolo, 1959: 183; Giannuzzi-Savelli et al., 1999: 50, 51, figs 93a–b; Ardovini & Cossignani, 2004: 136.
Janthina decollata Carpenter. – Küster, 1868: 6, pl. 1, figs 7–8, pl. 2, fig. 12.
Janthina globosa Swainson. – Lischke, 1871: 169; Lischke, 1874: 53; Hutton, 1904: 80; Moss, 1908: 28; Suter, 1913: 300, pl. 44, fig. 14; Hedley, 1918: M61; Bucknill, 1924: 150, pl. 5, fig. 20; Powell, 1937: 74, pl. 10, fig. 29; Okutani, 1956: 43, text-figs 1–2; Cernohorsky, 1972: 198, pl. 56, fig. 9; Powell, 1976: 107, pl. 17, fig. 29; Kay, 1979: 158, fig. 55A, D; Powell, 1979: 254, pl. 48, fig. 22; Redfern, 2001: 76, pl. 36, fig. 316; Morley, 2004: 102; Robertson, 2007a: 5, fig. 2; Spencer et al., 2009: 206; Raven & Bracegirdle, 2010: 27, bottom right fig.; Willan et al., 2010: 386, text-fig.; Hernández et al., 2011: 98, fig. 30 I; Janssen, 2012: 24, figs 5A–6B.
Janthina pallida var. minor Monterosato, 1878: 35.
Janthina nitens var. minor Monterosato, 1878: 35.
Janthina splendens Monterosato, 1884: 104 (“= J. nitens, var. minor ” Monterosato).
Amethistina laeta Monterosato, 1884: 105 (“= J. pallida, var. minor ” Monterosato).
Ianthina globosa var. decollata Carpenter. – Whitelegge, 1889: 262.
Janthina laeta (Monterosato).– Locard, 1898: 3, pl. 20, figs 31–34.
Janthina payraudeaui Locard in Locard & Caziot, 1901: 157 (refers to Payraudeau, 1826: 121, pl. 6, fig. 1).
Janthina sp. – Woodring, 1928: 405.
Violetta globosa (Swainson). – Iredale, 1929: 279; Allan, 1950: 95; Cotton, 1959: 376; Iredale & McMichael, 1962: 49; Kuroda et al., 1971: 246, pl. 62, figs 11–12.
Janthina (Violetta) globosa Swainson. – Powell, 1946: 77, pl. 10, fig. 29; Powell, 1957: 98, pl. 10, fig. 29; Powell, 1962: 91, pl. 10, fig. 29; Kira, 1962: 30, pl. 14, fig. 24; Abbott, 1974: 113, col. pl. 3, fig. 1179.
Ianthina prolongata Blainville. – Laursen, 1953: 28, figs 30–35c.
Janthina cf. pallida Thompson. – Berry, 1958: 27.
Janthina communis Lamarck. – Pasteur-Humbert, 1962: 52, fig. 71 (misidentification as J. janthina Linnaeus).
Janthina exigua Lamarck. – Hodgkin et al., 1966: 35, pl. 12, fig. 7 (misidentification).
Janthina pallida Thompson. – Wilson, 1993: 281, pl. 44, figs 38a–b (misidentification).
Janthina (Violeta) [sic] globosa (Swainson). – Rios, 1994: 101, pl. 33, fig. 414.
Janthina (Violetta) prolongata Blainville. – Okutani, 2000: 319, pl. 158, fig. 2.
Janthina (Janthina) prolongata Blainville. – Janssen, 2007a: 59, pl. 1, figs 5–6.
Janthina prolonga Blainville. – Severns, 2011: 198, upper fig (incorrect subsequent spelling of J. prolongata Blainville, 1822).
Type material. As with all living Janthina species other than J. janthina, Laursen (1953) did not discuss any type material of J. globosa, and provided no reasons for assigning particular names to particular species. Examination of the huge collections of Janthina specimens in world museums has demonstrated that Laursen (1953) recognized the five living species correctly, as was agreed by Robertson (2007a), although a little tentatively. As far as can be determined from the type material the writer has examined, Laursen also assigned the most appropriate names to the five species, but the more than 60 published names for living Janthina species must now be referred to type specimens that establish their identity unambiguously. The two specimens in UPSZTY illustrated by Laursen (1953: pl. 1, fig. 2) and referred to Helix janthina by Linnaeus (1764: 670) are Janthina globosa Swainson (UPSZTY756, marked with a letter “a”, and UPSZTY2849, marked with a letter “b”; Erica Sjolin UPSZTY pers. comm. 26 Sep 2012). No type material of J. globosa Swainson is present in NHMUK (K. Way NHMUK pers. comm. 05 Feb 2013). It seemed possible that some is present in Swainson’s material in the Manchester Museum. However, the catalogue of molluscan types in the Manchester Museum (McGhie, 2008) does not include any Swainson types. H. McGhie (Manchester Museum pers. comm. 27 Nov 2014) stated that he has been unable to recognize any Swainson types because Swainson’s material has been incorporated in the general collection and there is no means of identifying it. It is concluded that none of Swainson’s type specimens of Mollusca is recognisable in the Manchester Museum. No type material of Janthina globosa Blainville or of J. prolongata is present in MNHN, NHMUK, USNM or any other institutions the writer has consulted, and its location is unknown. Janthina iricolor, three syntypes NHMUK 1976168, from “ China ”, ex Cuming collection; two of the syntypes were illustrated by Yen (1942: 219, pl. 20, fig. 123, 2 images). The larger of the syntypes illustrated by Yen (1942: pl. 20, fig. 123, right image), NHMUK 1976168a, is here designated the neotype of both Janthina globosa Swainson, 1822 (Jan) and Janthina prolongata Blainville, 1822 (Aug).
Janthina nitens, no type material present in any museums the writer has consulted. Menke did not know the locality of his specimen. R. Janssen (SMF pers. comm. 18 Aug 2015) confirmed that no type material of J. nitens is present in the remnants of Menke’s collection in SMF. Therefore, the neotype of J. globosa and J. prolongata designated above, NHMUK 1976168a, is here also designated the neotype of Janthina nitens Menke, 1828. Dr K. Schniebs (Senckenberg Naturhistorische Sammlung Dresden, pers. comm. 23 Feb 2016) reported that all material of Janthina in Anton’s collection was lost in or after the end of world war two, so no type material remains for J. rosea. Therefore, the neotype of J. globosa, J. prolongata and J. nitens designated above, NHMUK 1976168a, is here also designated the neotype of Janthina rosea Anton, 1838. The remaining two syntypes of Janthina patula Philippi, ZMB 41985 (photographs sent by C. Zorn, ZMB pers. comm. 30 Jan 2016; Figs 30 F – G) are labelled “ Neapel ” (Naples). This name previously was assumed to be a synonym of J. pallida, but the deep sinus in the outer lip and the protruding, pointed anterior end of the columella demonstrate that the illustrated syntype is a tall, narrow specimen of J. globosa rather than of J. pallida. As the writer has seen only the illustrated photographs (Figs 30F–G), the illustrated syntype ZMB 41985a is here designated the lectotype of Janthina patula Philippi, 1844, in case the remaining paralectotype is not conspecific.
Type material of Carpenter’s (1857) Janthina species was not included in Carpenter’s illustrations of the Mazatlan fauna (Brann, 1966: 14). However, that is not surprising because, as Keen (1968) pointed out, Carpenter illustrated only his smaller specimens, with camera lucida drawings. Keen (1968: 408, 410, pl. 59, figs 78a–80) illustrated the type material in NHMUK of all three names proposed by Carpenter and recorded three syntypes of Ianthina decollata, demonstrating that they are typical specimens of J. globosa. Type material of all three names, from Mazatlan, western Mexico, is still present in NHMUK: I. decollata, one syntype remaining, NHMUK 1857.6.4.878 (K. Way NHMUK pers. comm. 05 Feb 2013).
The name Janthina nitens var. atlantica Mörch (1860: 280) was defined by a list of references, the first of which was “ Janthina communis Q. et G., Ast[rolabe], t. 29, fig. 1–4”, followed by a further six references (Mörch did not italicize Janthina in headings in this paper). The other references are to M. E. Gray (1842: pl. 48, fig. 1, and pl. 117a, figs 2b–c), Chenu (1859: 118, fig. 518), Woodward (1851: 148), Gray (1857: 52, fig. 30) and Cuvier (1808: pl. 1, figs 3–5). Most of these figures show J. globosa, and these and Mörch’s reference to the Mediterranean locality cited by Fabius Columna show that the name is a synonym of J. globosa. The original material illustrated in the figures referred to by Mörch (1860: 280) all constitutes syntypes of J. nitens var. atlantica. Kathe Jensen (ZMUC pers. comm. 18 Aug 2015) stated that she was unable to find type material in ZMUC. Quoy & Gaimard’s (1833: pl. 29, figs 1–4) illustration, supposedly of “ J. communis ”, i.e., J. janthina, from “Océan Atlantique”, shows a specimen with egg capsules attached beneath its float, and so is clearly not J. janthina, although the drawings are so crude that the species is not identifiable from this drawing. Also, the specimens illustrated by Quoy & Gaimard (1833: pl. 29) are not present in MNHN (P. Bouchet MNHN pers. comm. 5 Apr 2016). The location of any of the other specimens illustrated in the references cited by Mörch (1860: 280) also is unknown. Therefore, the neotype of J. globosa, J. prolongata, J. nitens and J. rosea designated above, NHMUK 1976168a, is here also designated the neotype of J. nitens var. atlantica.
It has been assumed previously that Monterosato’s (1878: 35) identification of Janthina pallida was correct. However, his type material is present in MCZR. Massimo Appolloni (MCZR) and Marco Oliverio (Department of Biology and Biotechnologies “Charles Darwin”, University of Rome 1 “La Sapienza”) sent the writer photographs of some of Monterosato’s type material. The syntype examined of Amethistina laeta Monterosato, 1884 (= J. pallida var. minor Monterosato, 1878), MCZR 23414/1, is a small specimen (H 11.8 mm), one of five specimens of Janthina globosa from Algiers, labelled “ Amethistina laeta 1884 Monts [Monterosato] Alger (Joly)”. Because of confusion about the application of this name, which (as with J. splendens) has usually been assumed to refer to J. pallida, the illustrated specimen (Fig. 30D), MCZR 23414/1, is here designated the lectotype of Amethistina laeta Monterosato, 1884. Janthina splendens Monterosato, 14 syntypes in MCZR; six syntypes are from Algiers, labelled “ J. splendens Monts Alger! (Joly)”, two from Alexandria, Egypt, labelled “ J. splendens Allesandria (Lothellerie) ”, two from “ Is. di Lipari ”, and four labelled “ Pal. coll. Di Blasi ”. The illustrated syntype (Fig. 30C, E) from Alexandria is a small specimen (H 13.7 mm) of J. globosa. Because of confusion about the application of this name, the illustrated specimen, MCZR 23423/1, is here designated the lectotype of Janthina splendens Monterosato, 1884. Janthina payraudeaui, type material not in MNHN, location unknown; referring to Payraudeau’s (1826: 121, pl. 6, fig. 1) illustration of a specimen J. globosa from Corsica. The neotype of Janthina globosa Swainson and J. prolongata Blainville designated above, NHMUK 1976168a, is here also designated the neotype of Janthina payraudeaui Locard, 1901.
Other material examined. Fossils: Philippine Islands: Janssen (2007a:59, pl. 1, figs 5A–6B) recorded and illustrated two small specimens of Janthina globosa, one from each of his localities Anda1 and Anda2,near the village of Anda on Cabarruyan Island,Lingayen Gulf, Pangasinan province,west coast of Luzon, Philippine Islands. A combination of planktonic foraminiferans and pteropods at this locality demonstrated a Piacenzian (late Pliocene) age (Janssen, 2007a: 110). Helwerda et al. (2014: 101) pointed out that the age of the Anda localities might be as young as Gelasian, based on planktonic foraminifera, and is uncertain at present; they are accepted as Piacenzian – Gelasian in the present paper.The small specimen, a little over 9 mm high, from Anda1 (RGM 517582; Janssen, 2007a: pl. 1, figs 5A–B) clearly reveals the lack of sculpture, near-spherical shape, anterior apertural prolongation, and moderately deep mid-outer lip sinus of J. globosa. Also, the specimen from Anda 2 (RGM 517583; Janssen, 2007a: pl. 1, figs 6A–B) reveals an incomplete but well-preserved Janthina protoconch. This material is critically important, as it is the first confirmation of the late Piacenzian – Gelasian (late Pliocene –earliest Pleistocene) occurrence of a living Janthina species.
Jamaica: Woodring (1928: 405) identified a small specimen from the famously diverse Pliocene locality at Bowden, Jamaica, as “ Janthina sp.”, and suggested it might be related to J. globosa. The Bowden “shellbed” has been dated as early Piacenzian, calcareous nannofossil zone NN16 (Aubry, 1993); as Piacenzian, based on planktonic Foraminifera (Berggren, 1993); as “early late Piacenzian” (Janssen, 1998: 97) based on planktonic Foraminifera, confirmed by the occurrence of the “pteropod” Cavolinia tridentata (Niebuhr, 1775), which did not evolve until Piacenzian time (Janssen, 1998: 105); as late Pliocene [i.e., Piacenzian] (Kohl & Robinson, 1998); and as 2.8–1.6 Ma, spanning the Plio-Pleistocene boundary (at this date, intended for late Gelasian–early Calabrian, the boundary dated at 1.8 Ma; Cotton, 1999).A late Piacenzian age is accepted here, recognising the rather poorly constrained age of this “shellbed”. The “shellbed” is highly heterogeneous and possibly formed as an olistostrome (B. M. Landau pers. comm. 2008), contains microfossils reworked from a range of ages (Kohl & Robinson, 1998) and certainly contains macrofossils from a wide range of environments. The lithostratigraphy was described in detail by Pickerill et al. (1998), who demonstrated several lenses of coarse-grained lithologies within the lower part of the formation.Kohl & Robinson (1998: 43) concluded from the Foraminifera that the Bowden Formation was deposited by sediment gravity flows: “… the present study supports the downslope transport interpretation of other investigators … a shallow-water (inner neritic) fauna containing molluscs, corals and benthic foraminifera was redeposited in an outer neritic environment”. The writer has examined Woodring’s specimen (USNM 135575, from USGS locality 2580, collected by J. Henderson). It is stark white, incomplete (part of the base originally missing), very small (H 5.7, D 4.7 mm; Woodring, 1928: 405), and has now largely disintegrated into five main fragments and several smaller ones. It is very thin-shelled, with an obvious but low, rounded spire as in Janthina globosa, a narrow inner lip reflected over the very narrow umbilical chink, and an almost completely smooth, evenly and strongly inflated exterior representing an originally subspherical, naticiform shell. The largest basal fragment (maximum dimension 4.2 mm; Fig. 31) bears very faint growth lines revealing a moderately deep sinus in the centre of the outer lip, agreeing with that of Recent specimens of J. globosa. One growth line is almost complete, and many others are faintly visible parallel to the complete one, all visible only in strongly oblique light.The protoconch is missing.Because of its evenly subspherical shape, low but obvious, rounded spire, lack of sculpture other than faint growth lines, and the moderately deep sinus with its apex located in the centre of the outer lip, the Bowden specimen also is identified as a late Piacenzian fossil specimen of J. globosa.
Mediterranean: Janssen (2012: 24, figs 6A–7B, 45H) recorded Janthina globosa (six samples) and another possibly distinct taxon referred to “ Janthina janthina?” (19 samples) from late Pleistocene–Holocene core tops collected throughout the eastern Mediterranean Sea. The protoconch illustrated (Janssen, 2012: fig. 45H) as that of J. janthina is shorter and inclined at a much greater angle to the teleoconch coiling axis than in Janthina species illustrated previously (Robertson, 1971: pl. 5, fig. 17) and although the juvenile teleoconch (Janssen, 2012: figs 7A–B) lacks axial ridgelets, it closely resembles those studied here. Also, Robertson (1971: 7) described the angle of the protoconch to the teleoconch coiling axis as varying between 10° and 50° in J. janthina, and those examined here (Figs 32A–D) lie at a high angle to the teleoconch, indicating that Janssen’s (2012) identification is correct. Specimens assigned to J. globosa (Janssen, 2012: figs 6A–B) also are correctly identified.
Present–day samples from Australia and New Zealand: Australia: Northern Territory: Port Essington (AMS). Western Australia: Broome (NMV);False Bay (AMS). South Australia: Encounter Bay (SAM). New South Wales: Ulladulla (AMS); Nelson Bay (AMS); Curl Curl Beach (C83054, AMS); Maroubra (SAM; C51088, AMS); Collaroy Beach (C79166, C77799, AMS); Long Reef (AMS); Palm Beach (AMS); La Perouse (AMS); Coogee (C56764, AMS); Middle Harbour, Port Jackson (NMV); Manly Beach (NMV);Terrigal (AMS); Port Kembla (AMS); South Ocean Beach, Bermagui (AMS); Putty Beach, Kilcare (AMS); Wollongong (C11239, AMS); Mallacoota (NMV); Ulladulla (C83053, AMS). Queensland: Caloundra (AMS); Fairfax I., Bunker Group (C69053, AMS); Keppell Bay (NMV); Lady Elliott I. (C73001, AMS). Tasmania: Tasmania (many, NMNZ M210990).
Lord Howe Island (NMV; C13799, AMS); Blimey Beach (AMS). Norfolk Island: C59408 (AMS); specimen observed, AGB, in Mrs M. Hoare colln, Norfolk. Kermadec Islands: Raoul I. (NMV; AWM; AMS; NMNZ M200951, 10; M22294, 70); Denham Bay, Raoul I. (GNS WM8273, 1; NMNZ M201609, 1); 1.8km NW of Napier I., Raoul I. (NMNZ M226575, 1).
New Zealand: Spirits Bay (NMNZ M03935, 1); Tapotupotu, SE of Cape Reinga (NMNZ M308661, 30); Waikuku Beach, S of North Cape (NMNZ M044726, 4); Matai Bay, Karikari Peninsula (GNS RM3760, 2); Cable Bay, Doubtless Bay (GNS RM4063, 1); outer Bay of Islands (NMNZ M308652, 3); Otahei Bay, Bay of Islands (NMNZ M087147, 3); Russell, Bay of Islands (AWM); Bream Head, Northland (AWM 18130); Mangawai Heads, Northland (GNS RM333, 2; AWM 17547); Waipu Cove, S of Whangarei (GNS RM4322, 3); Pakiri Beach, N of Leigh (GNS RM5320, 4); Whangateau, Leigh (AWM 30150); Piha Beach, W Auckland (GNS RM5310, 1); Muriwai Beach, W Auckland (GNS M5321, 3); Auckland (S492, S780, Suter Colln, GNS);Takapuna Beach, Auckland (AWM 18131); Orakei, Auckland (GNS Suter colln, S780, 1); Auckland harbour (GNS Suter colln, S492, 1); Kaitoke Beach, Great Barrier I. (NMNZ M087145, 1); W coast Awhitu Peninsula, SW of Waiuku, SW Auckland (NMNZ M087148, 3; M277738, 1; M277739, 2); Matakana I., Bay of Plenty (AWM 33258; AWM 42753, 53; NMNZ M111096, 2); Papamoa Beach, Bay of Plenty (NMNZ M120140, 100; M120141, 40); Waihau Bay, Whangaparaoa, near East Cape (NMNZ M15032, 1).
Distribution. Janthina globosa is among the least common living Janthina species around New Zealand. It is recorded only from the northeastern North Island warm-water region, as far south as Awhitu Peninsula, SW Auckland, on the west coast and the eastern Bay of Plenty on the east coast. Nevertheless, samples of some hundreds of specimens have been collected in this area from time to time. It is much more common around eastern, northern and western Australia, and is one of the most common species in the North Pacific. Savilov (1969: 402) noted that the distribution of J. globosa in the Pacific is very similar to that of J. janthina, and many large schools contained both species, although J. globosa was much the less common. It was collected at 81 of the 393 Vityaz stations with Janthina. “Exceptionally large concentrations were observed in … the north and south subtropical current systems, as well as in the eastern regions of the Trade Wind Current. They also occurred near the coast of California. Only single young individuals (1–3 mm) were observed in the western areas of the North Trade Wind Current and in the Trade Wind Countercurrent” (Savilov, 1969: 402). Berry (1958) reported that it is “of only occasional Californian occurrence”. As noted above, Okano & Wada (2012) provided data on height and egg-capsule incidence for a collection of about 170 specimens cast ashore in September 2010 on the beaches of Iwami-cho, eastern Tottori Prefecture, Japan Sea coast of Honshu. Egg capsules were present in 41 of these specimens (24%); the largest shell was 40.35 mm high, and none with shells shorter than 27.4 mm had egg capsules attached to their floats. Suzuki & Shiga (2008) also recorded specimens rather surprisingly cast ashore in Hokkaido, the northernmost island of Japan.
Most importantly for the evolution of neustonic Epitoniidae, Piacenzian or possibly Gelasian fossil specimens of Janthina globosa are recorded here from two localities, in Jamaica and the Philippine Islands. Late Pleistocene–Holocene fossils are also reported widely in the Mediterranean Sea. This species has a much longer fossil record than any other living Janthina species, and is critical for demonstrating that a living Janthina species already had achieved a wide, presumably cosmopolitan distribution before J. chavani became extinct. This confirms that J. globosa and J. janthina had distinct origins.
Dimensions. See Table 6.
Diagnosis. Moderately large (to c. 40 mm high), spire moderately tall, whorls strongly and evenly convex, suture deeply impressed; exterior lightly polished to glossy, without obvious sculpture. Sinus occupying entire height of outer lip, symmetrically V-shaped, deep but less so than in J. exigua and J. umbilicata; apex of sinus at centre of lip. Anterior end of columella drawn out anteriorly, forming a short, triangular projection. Most specimens uniform deep violet, slightly paler below suture than elsewhere; a few specimens paler. Lays ovate-triangular egg capsules on underside of float.
Remarks. The large size sets Janthina globosa apart from all living Janthina species other than J. janthina. Many shells reach 30 mm in height; Suter (1913: 300) recorded a New Zealand specimen with H 41, D 38 m, although it is not clear what this was based on, as a specimen this large is not present in his collection in GNS. As noted above, Okano & Wada (2012) also recorded Japanese specimens up to 40.35 mm high. Several large specimens examined (e.g., Gove, Northern Territory, Australia, NMNZ M042102, 2 specimens) have an unusually pale, matt, milky bluishwhite shell, similar in tone to most specimens of J. pallida, but most specimens retain their deep violet, glossy shells until a large size. Its lack of sculpture, anterior prolongation of the columella, and polished, strongly and evenly convex whorls also make this species easily recognised. The sinus in the outer lip also is significantly deeper than that of J. pallida. The radular teeth of J. globosa (Laursen, 1953: fig. 33) are narrower and less strongly hooked than those of all other Janthina species. Priolo (1959: 183–184) provided a long list of references to usages of this name and its many synonyms in the literature on living Mediterranean molluscs.
Berry (1958) adopted the name Janthina prolongata for this species because he considered that “the recent … monograph by Laursen (1953) is … inconsistent in its application of the priority rule”. Berry (1958) thought that Swainson’s (1822: pl. 85) plate of Janthina was published in 1823, whereas he correctly dated Blainville’s (1822) monograph. Therefore, Berry also adopted the name J. globosa Blainville, 1822 for the species identified here as J. umbilicata, as he thought J. globosa Blainville was the senior homonym of J. globosa Swainson. Berry’s (1958) conclusions were followed by Keen (1971). However, Swainson’s (1822: pl. 85) plate was published in January 1822, whereas Blainville’s monograph was published in August 1822; these dates were confirmed by Rosenberg (2017).
A specimen of Janthina globosa collected alive after being cast ashore on a beach in northern New South Wales was photographed by Denis Riek [Brunswick Heads, NSW, pers. comm. 12 Nov 2015; illustrated on his web page (Riek, 2017); Fig. 5E] suspended from its float, with its head expanded but its snout rather contracted, revealing forked cephalic tentacles, and bearing pale pink egg capsules beneath the float. The external anatomy appears to be identical to that of J. janthina.
Time range. Late Piacenzian–Gelasian (at Bowden, Jamaica and Anda, Cabarruyan Island, Luzon, Philippines) to living, earliest record poorly constrained; recorded widely from late Pleistocene–Holocene core tops in the eastern Mediterranean.
description: Published as part of Beu, Alan G., 2017, Evolution of Janthina and Recluzia (Mollusca: Gastropoda: Epitoniidae), pp. 119-222 in Records of the Australian Museum (Rec. Aust. Mus.) (Rec. Aust. Mus.) 69 (3) on pages 181-185, DOI: 10.3853/j.2201-4349.69.2017.1666, http://zenodo.org/record/4677010