Adaptations to hydrothermal vent life in Kiwa tyleri, a new species of yeti crab from the East Scotia Ridge, Antarctica

Hydrothermal vents in the Southern Ocean are the physiologically most isolated chemosynthetic environments known. Here, we describe Kiwa tyleri sp. nov., the first species of yeti crab known from the Southern Ocean. Kiwa tyleri belongs to the family Kiwaidae and is the visually dominant macrofauna of two known vent sites situated on the northern and southern segments of the East Scotia Ridge (ESR). The species is known to depend on primary productivity by chemosynthetic bacteria and resides at the warm-eurythermal vent environment for most of its life; its short-range distribution away from vents (few metres) is physiologically constrained by the stable, cold waters of the surrounding Southern Ocean. Kiwa tylerihas been shown to present differential life history adaptations in response to this contrasting thermal environment. Morphological adaptations specific to life in warm-eurythermal waters, as found on – or in close proximity of – vent chimneys, are discussed in comparison with adaptations seen in the other two known members of the family (K. hirsuta, K. puravida), which show a preference for low temperature chemosynthetic environments

The evolution and population genetics of hydrothermal vent megafauna from the Scotia Sea

This project used a variety of genetic markers to investigate the evolution and population genetics of hydrothermal vent fauna that were recovered from the Scotia Sea, in the Atlantic sector of the Southern Ocean. The origins of one of these species, an undescribed species of Kiwa sp. found on the East Scotia Ridge (ESR) and its constituent family Kiwaidae, a group of vent and seep-associated decapod squat lobsters (infraorder Anomura) was investigated using a concatenated nine-gene dataset and key divergences were dated using fossil calibrations. These results confirm earlier research showing Kiwaidae reside in the superfamily Chirostyloidea, but form a monophyletic clade with the non-chemosynthetic family Chirostylidae and not Eumunididae. Chirostyloid families diverged in the Cretaceous, although extant Kiwaidae radiated in the Eocene, consistent with many other chemosynthetic taxa that appear recently derived. The basal tree position of Pacific species (and the Alaska location of a likely stem-lineage kiwaid fossil) suggests kiwaids originated in the East Pacific. Within a Southern Hemisphere clade, the divergence between the southeastern Pacific K. hirsuta and a non-Pacific lineage (Kiwa sp. ESR and Southwest Indian Ridge kiwaids) is no earlier than 25.9 Ma, consistent with a spread from the Pacific into the Scotia Sea and beyond via now-extinct active ridge connections or mediated by a Miocene onset of the Antarctic Circumpolar Current (ACC) through a newly-opened Drake Passage. This project also investigated the population genetics of three undescribed species found at two vent fields ~ 440 km apart at either end of the ESR: Kiwa sp., a peltospirid gastropod and Lepetodrilus sp. limpets. Lepetodrilus sp. was also found at the Kemp Caldera, a submerged part of the South Sandwich Islands (SSI). Analyses of cytochrome c oxidase subunit 1 (COI) as well as microsatellite loci developed from Roche 454 sequence libraries revealed no differentiation along the ESR for all three species consistent with panmixia, or the dominance of non-equilibrium processes between vent field colonies within a metapopulation, possibly enhanced further by cold-induced arrested larval development. Despite apparent connectivity along the ESR, both COI and microsatellites revealed differentiation between ESR limpets and Kemp Caldera limpets ~ 95 km to the east, possibly owing to the hydrographic isolation of the caldera. Both COI and microsatellite diversity patterns were consistent with recent ( These results highlight the role of larval dispersal of vent fauna along active spreading ridges, both in maintaining vent metapopulations across vent colonies prone to stochastic birth and extinction in the short term, but also in the spread of taxa globally and the formation of biogeographic provinces. The likelihood that the three species presented here exist at vents east of the ESR and SSI, prompts further exploration along ridges in the South Atlantic, in order to investigate the effect of the ACC in enhancing gene flow and delineating biogeographic provinces.This thesis is not currently available in ORA

Gigantopelta aegis Chen & Linse & Roterman & Copley & Rogers 2015, SP. NOV.

GIGANTOPELTA AEGIS SP. NOV. (FIGS 2–7) <p> <i>Type material</i></p> <p> Holotype. Shell diameter 37.61 mm, 99% ethanol, Figure 3D–F. Longqi vent field, Southwest Indian Ridge, 37°47.03′S, 49°38.97′E (‘Tiamat’), 2785 m deep, RRS <i>James Cook</i> expedition JC67, ROV <i>Kiel 6000</i> Dive 142, 29.xi.2011, leg. J. T. Copley (NHMUK 20150070). Paratypes. One dissected specimen, 99% ethanol (shell diameter 35.24 mm, Fig. 4C, D; NHMUK 20150071); growth series of five specimens, 99% ethanol (NHMUK 20150072); growth series of five specimens, 99% ethanol OUMNH. ZC. 2013.02.003); two specimens, 99% ethanol (CAMZM 2015.3.1 -2); growth series of five specimens (SMNH Type Collection 8451). All paratypes above have the same collection data as holotype. Five specimens, 10% buffered formalin (NHMUK 20150073): Longqi vent field, Southwest Indian Ridge, 37°47.03′S, 49°38.96′E (‘Tiamat’ chimney), 2783 m deep, RRS <i>James Cook</i> expedition JC67, ROV <i>Kiel 6000</i> Dive 140, 27.xi.2011, leg. J. T. Copley (NHMUK 20150073).</p> <p> <i>Other material examined</i></p> <p>Approximately 200 specimens, same collection data as the holotype.</p> <p> <i>Etymology</i></p> <p>Aegis (Latin), the shield of Zeus and Athena. The specific name is an allusion of the thick and large sulphidecovered operculum to the mythical shield.</p> <p> <i>Zoobank registration</i> urn:lsid:zoobank.org:act: 45E3E373-E126-4179-B1EB- D583FCFB3D12)</p> <p> <i>Description/Diagnosis</i></p> <p> <i>Shell:</i> Shell (Fig. 4B) globose, three to four whorls, trochiform to neritiform. Spire depressed. Aperture holostomous. Tightly coiled. Suture deep. Aperture very large, circular, body whorl to aperture length ratio approximately 1:0.65 (average of 100 specimens). Protoconch (Fig. 5B) 0.5 whorls, about 210 μm in length, sculpture unknown (surface layer of examined specimens affect- ed by dissolution). Thick, orange to reddish sulphide layer covers periostracum. Periostracum dark olive with sulphides removed. Ostracum milky white. Ostracum thin, fragile without sulphide and periostracum. Periostracum slightly recurved at aperture. Columellar folds lacking. Callus extends extensively, covering columellar region. Area around callus flattened (dark area in Fig. 3F). Shell smooth, lacking sculpture. Fine growth lines, subtle spiral cords present under sulphide layer. Maximum shell diameter 44.2 mm.</p> <p> <i>Operculum:</i> Operculum (Fig. 3E, F) corneous, thin, flaky near the fringe, multispiral, covered by thick sulphide layer except outermost whorl, same material as those covering shell. Juvenile operculum lacking sulphide layer. Moderately thick, opaque, with concave shape (Fig. 5B).</p> <p> <i>Radula:</i> Radula (Fig. 6B) rhipidoglossate. Ribbon in adults approximately 0.5 mm wide and 4 mm long. Formula ∼50 + 4 + 1 + 4 + ∼50. Central, lateral teeth (Fig. 6D) with sharp cusps. Central tooth rectangular. Lateral teeth bear a protrusion near the base. Marginal teeth (Fig. 6F) elongate with truncate distal ending, dividing into ∼20 denticles.</p> <p> <i>Soft parts (Fig. 7B):</i> Foot muscular, large. Fully retractable. Pale white when alive. Small epipodial tentacles present, surrounding posterior two-thirds of operculum. Cephalic tentacles thick, broad at base, tapering distally. Snout tapering and thick. Oesophageal gland huge (see Fig. 7B). Intestines forming a simple loop. Ctenidium bipectinate. Sexes separate. Gonads rather displaced towards the head-foot. Shell muscle large, horse-shoe shaped.</p> <p> <i>Distribution:</i> Only known from Longqi vent field, SWIR (approximately 37°47.03′S, 49°38.96′E), around 2700 m depth. Found mostly on areas of diffuse flow but also on chimneys of active black smokers.</p> <p> <i>Remarks</i></p> <p> Similar to <i>Gigantopelta chessoia</i> sp. nov.; see Comparative remarks above for comparison. The sulphide covering of the shell and that forming the thick coating on the operculum is remarkable. The coating only covers the outer side, and can be removed from the operculum intact by inserting a blade in between. The adult shells are completely covered with sulphide. Sulphide deposition appears to start very early in development, and from the protoconch; as in young specimens (∼ 5 mm maximum diameter) sulphide is only present as a tablet on the apex and not covering the whole shell. The shell parameters are given in Table 2. The relationships between the six parameters measured were investigated, and they were linear across all life stages. Figure 8B shows a scatter plot of shell diameter against shell height.</p>Published as part of <i>Chen, Chong, Linse, Katrin, Roterman, Christopher N., Copley, Jonathan T. & Rogers, Alex D., 2015, A new genus of large hydrothermal vent-endemic gastropod (Neomphalina: Peltospiridae), pp. 319-335 in Zoological Journal of the Linnean Society (Zool. J. Linn. Soc.) (Zool. J. Linn. Soc.) 175 (2)</i> on pages 327-329, DOI: 10.1111/zoj.12279, <a href="http://zenodo.org/record/5338416">http://zenodo.org/record/5338416</a&gt

A new genus of large hydrothermal vent-endemic gastropod (Neomphalina: Peltospiridae)

Recently discovered hydrothermal vent fields on the East Scotia Ridge (ESR, 56–60°S, 30°W), Southern Ocean, and the South West Indian Ridge (SWIR, 37°S 49°E), Indian Ocean, host two closely related new species of peltospirid gastropods. Morphological and molecular (mitochondrial cytochrome c oxidase subunit I, COI) characterization justify the erection of Gigantopelta gen. nov. within the Peltospiroidae with two new species, Gigantopelta chessoia sp. nov. from ESR and Gigantopelta aegis sp. nov. from SWIR. They attain an extremely large size for the clade Neomphalina, reaching 45.7?mm in shell diameter. The oesophageal gland of both species is markedly enlarged. Gigantopelta aegis has a thick sulphide coating on both the shell and the operculum of unknown function. The analysis of a 579-bp fragment of the COI gene resulted in 19–28% pairwise distance between Gigantopelta and six other genera in Peltospiridae, whereas the range amongst those six genera was 12–28%. The COI divergence between the two newly described species of Gigantopelta was 4.43%. Population genetics analyses using COI (370?bp) of 30 individuals of each species confirmed their genetic isolation and indicate recent rapid demographic expansion in both species. <br/

A new Southern Ocean species in the remarkable and rare amphipod family Podosiridae (Crustacea: Amphipoda) questions existing systematic hypotheses.

The amphipod family Podosiridae is unusual in that it combines morphological elements of the disparate families Podoceridae and Eusiridae. Here, we describe a new species in the family from specimens collected from the Southern Ocean in the vicinity of the South Orkney Islands and South Shetland Islands. We present mitochondrial (COI and 16S) and nuclear (18S) nucleic acid sequences for this and a congeneric species and use these to investigate the phylogenetic placement of Podosiridae within the Amphipoda. Our results do not provide evidence for a close relationship between Podosiridae and Podoceridae or Eusiridae, suggesting that the superficial similarity between these families is the result of morphological convergence. Instead, it is likely that Podosiridae are more closely related to families within Amphilochidira, such as Stenothoidae. Definitive placement of Podosiridae in the Amphipoda awaits further specimen collection, additional nucleotide data (including sequences from the Hyperiopsidae and the Vitjazianidae) and a more directed analysis of relationships within this portion of the amphipod phylogeny

Gigantopelta chessoia Chen & Linse & Roterman & Copley & Rogers 2015, SP. NOV.

GIGANTOPELTA CHESSOIA SP. NOV. (FIGS 2&ndash;7) &lt;p&gt; &lsquo;Peltospiroidea n. sp. &rsquo; &ndash; Rogers &lt;i&gt;et al&lt;/i&gt;., 2012: 7, fig. 3d. &lsquo;Undescribed species of peltospiroid gastropod&rsquo; &ndash; Marsh &lt;i&gt;et al&lt;/i&gt;., 2012: 6, fig. 5c, j.&lt;/p&gt; &lt;p&gt; &lt;i&gt;Type material&lt;/i&gt;&lt;/p&gt; &lt;p&gt; Holotype. Shell diameter 36.30 mm, 99% ethanol, Figure 3A&ndash;C. E 2 segment, East Scotia Ridge, 56&deg;05.31&prime;S, 30&deg;19.10&prime;W (&lsquo;Cindy&rsquo;s Castle&rsquo;), 2606 m deep, RRS &lt;i&gt;James Cook&lt;/i&gt; expedition JC42, ROV &lt;i&gt;Isis&lt;/i&gt; Dive 130, 20.i.2010, leg. A. D. Rogers (NHMUK 20150066). Paratypes. One dissected specimen, 99% ethanol (shell diameter 31.12 mm, Fig. 4A, B; NHMUK 20150067); growth series of five specimens, 99% ethanol (NHMUK 20150068). The above two lots have same collection data as the holotype. Growth series of five specimens, 99% ethanol (OUMNH. ZC.2013.02.002); two specimens, 99% ethanol (CAMZM 2015.2.1 -2); growth series of five specimens, 99% ethanol (SMNH Type Collection 8450); five specimens, 10% buffered formalin (NHMUK 20150069). Collection data for the latter three lots: E2 segment, East Scotia Ridge, 56&deg;05.34&prime;S, 30&deg;19.07&prime;W (&lsquo; Cindy&rsquo;s Castle&rsquo;), depth 2644 m, RRS &lt;i&gt;James Cook&lt;/i&gt; expedition JC42, ROV &lt;i&gt;Isis&lt;/i&gt; Dive 134, 24.i.2010, leg. A. D. Rogers.&lt;/p&gt; &lt;p&gt; &lt;i&gt;Other material examined&lt;/i&gt;&lt;/p&gt; &lt;p&gt; Approximately 200 specimens collected on RRS &lt;i&gt;James Cook&lt;/i&gt; expedition JC42 with ROV &lt;i&gt;Isis&lt;/i&gt;, on dives 130, 134, and 141. Collection data for dive 130: same as holotype; dive 134: same as listed for paratype series; dive 141: E9 segment, East Scotia Ridge, 60&deg;02.81&prime;S, 29&deg;58.71&prime;W (&lsquo;Marsh Tower&rsquo;), depth 2394 m, RRS &lt;i&gt;James Cook&lt;/i&gt; expedition JC42, ROV &lt;i&gt;Isis&lt;/i&gt; Dive 141, 30.i.2010, leg. A. D. Rogers.&lt;/p&gt; &lt;p&gt; &lt;i&gt;Etymology&lt;/i&gt;&lt;/p&gt; &lt;p&gt;The species is named after the ChEsSo (Chemosynthetically-driven ecosystems south of the Polar Front: biogeography and ecology) Consortium (Natural Environment Research Council (NERC) Grant NE/DO 1249X/1), which led to the discovery of ESR hydrothermal vents and this species.&lt;/p&gt; &lt;p&gt; &lt;i&gt;Zoobank registration&lt;/i&gt; urn:lsid:zoobank.org:act: D46EB848-506D-45B7-8D05- 35535592BD1E&lt;/p&gt; &lt;p&gt; &lt;i&gt;Description/Diagnosis&lt;/i&gt;&lt;/p&gt; &lt;p&gt; &lt;i&gt;Shell:&lt;/i&gt; Shell (Fig. 4A, B) globose, three to four whorls, coiled tightly with a deep suture. Spire depressed. Aperture roughly circular, very large. Ratio of shell diameter to aperture length approximately 1:0.633 (average of 100 specimens). Shell trochiform to neritiform, holostomous. Protoconch (Fig. 5A) consists of 0.5 whorls, diameter about 210 &mu;m. Irregular reticulate ornament present initially, becoming obsolete distally. Suture around protoconch very deep. Teleoconch smooth, no distinct sculpture. Subtle growth lines, irregular protuberances present. Growth lines stronger on the body whorl, especially near the aperture. Periostracum thick, dark olive, enveloping the aperture. Ostracum and hypostracum milky white. Thin, fragile without periostracum. Columellar folds lacking. Callus extends to slightly cover columellar. Area around callous concave. Maximum shell diameter 45.7 mm.&lt;/p&gt; &lt;p&gt; &lt;i&gt;Operculum:&lt;/i&gt; Operculum (Fig. 3C) with central nucleus, multispiral, thin, flaky on fringe. Operculum fringe often damaged. Juveniles operculum thin, semitransparent, fringe not flaky (Fig. 5C).&lt;/p&gt; &lt;p&gt; &lt;i&gt;Radula:&lt;/i&gt; Radula (Fig. 6A) rhipidoglossate. Ribbon approximately 0.5 mm wide and 4 mm long in adults. Formula &sim;50 + 4 + 1 + 4 + &sim;50. Central, lateral teeth cusp-like, pointed (Fig. 6C). Marginal teeth long, slender, bearing &sim;20 denticles at distal end (Fig. 6E). Central tooth triangular, very broad at base, tapering dis- tally, smooth, no sculpture. Lateral teeth solid, bearing a clear protrusion at base.&lt;/p&gt; &lt;p&gt; &lt;i&gt;Soft parts (Fig. 7A):&lt;/i&gt; Foot muscular, large. Fully retractable into shell, red when alive. Small epipodial tentacles present, surrounding posterior two-thirds of operculum. Cephalic tentacles thick, triangular, broad at base and thinning towards tips. Eyes lacking. Snout tapering, thick. Oesophageal gland huge, approximately same size as aperture. Ctenidium bipectinate. Sexes separate. Shell muscle large, horse-shoe shaped. Intestine forms a simple loop.&lt;/p&gt; &lt;p&gt; &lt;i&gt;Distribution&lt;/i&gt;&lt;/p&gt; &lt;p&gt;Only known from hydrothermal vents on segment E2 (56&deg;05.2&prime;S to 56&deg;05.4S, 30&deg;19.00&prime;W to 30&deg;19.35&prime;W) and E9 (60&deg;02.50&prime;S to 60&deg;03.00&prime;S, 29&deg;58.60&prime;W to 29&deg;59.00&prime;W) of ESR. This species forms dense aggregations rather close to vent effluents.&lt;/p&gt; &lt;p&gt; &lt;i&gt;Remarks&lt;/i&gt;&lt;/p&gt; &lt;p&gt; The dispersal mechanism is inferred to be nonplanktotrophic from the protoconch, presumably with a planktonic dispersal stage. Table 2 shows the shell parameters of &lt;i&gt;G. chessoia&lt;/i&gt;. The relationships between the six shell parameters measured were investigated and they were all linear across all life stages. Figure 8 shows a scatter plot of shell diameter against shell height. See Rogers &lt;i&gt;et al&lt;/i&gt;. (2012) for details on location of hydrothermal vent sites.&lt;/p&gt; &lt;p&gt; &lt;i&gt;Comparative remarks&lt;/i&gt;&lt;/p&gt; &lt;p&gt; Similar to &lt;i&gt;Gigantopelta aegis&lt;/i&gt; sp. nov. described below. &lt;i&gt;Gigantopelta chessoia&lt;/i&gt; can be distinguished as it has a taller spire, less extensive callus, and area around callus is concave and not flattened as in &lt;i&gt;G. aegis&lt;/i&gt;. Differences are seen in the structure of the radula. The central tooth of &lt;i&gt;G. chessoia&lt;/i&gt; is much wider at the base and triangular compared with that of &lt;i&gt;G. aegis&lt;/i&gt;, which is rectangular. Lateral teeth are sculptured in both species, but the marks occur nearer to the base of the teeth in &lt;i&gt;G. aegis&lt;/i&gt;. &lt;i&gt;Gigantopelta chessoia&lt;/i&gt; can also be easily distinguished by the lack of sulphide deposits on the shell and operculum, at least from &lt;i&gt;G. aegis&lt;/i&gt; found in Longqi Field, the only known habitat to date. Similarly, the operculum in &lt;i&gt;G. aegis&lt;/i&gt; is much thicker than &lt;i&gt;G. chessoia&lt;/i&gt; at all life stages.&lt;/p&gt;Published as part of &lt;i&gt;Chen, Chong, Linse, Katrin, Roterman, Christopher N., Copley, Jonathan T. &amp; Rogers, Alex D., 2015, A new genus of large hydrothermal vent-endemic gastropod (Neomphalina: Peltospiridae), pp. 319-335 in Zoological Journal of the Linnean Society (Zool. J. Linn. Soc.) (Zool. J. Linn. Soc.) 175 (2)&lt;/i&gt; on pages 323-327, DOI: 10.1111/zoj.12279, &lt;a href="http://zenodo.org/record/5338416"&gt;http://zenodo.org/record/5338416&lt;/a&gt

Gigantopelta Chen & Linse & Roterman & Copley & Rogers 2015, GEN. NOV.

GIGANTOPELTA GEN. NOV. &lt;p&gt; &lt;i&gt;Type species&lt;/i&gt;&lt;/p&gt; &lt;p&gt; &lt;i&gt;Gigantopelta chessoia&lt;/i&gt; sp. nov., by original designation.&lt;/p&gt; &lt;p&gt; &lt;i&gt;Etymology&lt;/i&gt;&lt;/p&gt; &lt;p&gt;Giganteus (Latin), gigantic; Pelta (Latin), shield. This refers to the extremely large adult shell size of the species in this genus for the family Peltospiridae. The genus name is feminine.&lt;/p&gt; &lt;p&gt; &lt;i&gt;Zoobank registration&lt;/i&gt; urn:lsid:zoobank.org:act: C25960CA-B974-452C-AE24- B128FF1CEA0F&lt;/p&gt; &lt;p&gt; &lt;i&gt;Diagnosis&lt;/i&gt;&lt;/p&gt; &lt;p&gt;Shell extremely large for family, reaching 45 mm in adult shell length. Shell globose, rather loosely coiled with deep suture, three to four whorls. Spire depressed. Protoconch consisting of 0.5 whorls. Aperture very large, circular, expanding rapidly. Thick, dark olive periostracum enveloping edge of aperture. Shell milky white and thin, not nacreous. Columellar folds lacking. Concentric, multispiral operculum present. Foot large. Cephalic tentacles thick, broad, triangular, thinning towards tips. Eyes lacking. Snout tapering and thick. Oesophageal gland hypertrophied. Single, bipectinate ctenidium. Sexes separate. Epipodial tentacles present surrounding operculum. Radula rhipidoglossate, formula &sim;50 + 4 + 1 + 4 + &sim;50. Central, lateral teeth strong, solid with smooth cusps. Marginal teeth long, slender, truncate, divided into about 20 toothlets towards distal end.&lt;/p&gt; &lt;p&gt; &lt;i&gt;Remarks&lt;/i&gt;&lt;/p&gt; &lt;p&gt; Adult &lt;i&gt;Gigantopelta&lt;/i&gt; are easily distinguished from all other described peltospirids by their extremely&lt;/p&gt; &lt;p&gt; &lt;i&gt;COI&lt;/i&gt;, cytochrome c oxidase subunit I&lt;/p&gt; &lt;p&gt; large shell size. Furthermore, &lt;i&gt;Gigantopelta&lt;/i&gt; can be distinguished from the limpet-like peltospirid genera &lt;i&gt;Ctenopelta&lt;/i&gt; War&eacute;n &amp; Bouchet, 1993, &lt;i&gt;Echinopelta&lt;/i&gt; McLean, 1989, &lt;i&gt;Hirtopelta&lt;/i&gt; McLean, 1989, &lt;i&gt;Nodopelta&lt;/i&gt; McLean, 1989, and &lt;i&gt;Rhynchopelta&lt;/i&gt; McLean, 1989, by having a coiled shell with three to four whorls. It can be distinguished from the three skeneiform genera, &lt;i&gt;Pachydermia&lt;/i&gt; War&eacute;n &amp; Bouchet, 1989, &lt;i&gt;Depressigyra&lt;/i&gt; War&eacute;n &amp; Bouchet, 1989, and &lt;i&gt;Lirapex&lt;/i&gt; War&eacute;n &amp; Bouchet, 1989, by its inflated form with a much more depressed spire and larger aperture. The shell surface is nearly smooth, which differs from all peltospirid genera except &lt;i&gt;Depressigyra&lt;/i&gt;. The shell roughly resembles that of &lt;i&gt;Peltospira&lt;/i&gt;, but has a more tightly coiled initial whorl, and lacks lamellar sculpture. Analysis of the soft parts shows an enlarged oesophageal gland, a feature previously only known from the &lsquo;scaly-foot gastropod&rsquo; &lt;i&gt;Chrysomallon squamiferum&lt;/i&gt; Chen &lt;i&gt;et al&lt;/i&gt;., 2015 (War&eacute;n &lt;i&gt;et al&lt;/i&gt;., 2003; Chen &lt;i&gt;et al&lt;/i&gt;., 2015), which is also the only other known peltospirid to attain a similar size. In &lt;i&gt;C. squamiferum&lt;/i&gt; the oesophageal gland houses symbiotic bacteria, but it is unclear whether this is also the case for &lt;i&gt;Gigantopelta&lt;/i&gt;. &lt;i&gt;Gigantopelta&lt;/i&gt; can be distinguished from &lt;i&gt;Chrysomallon&lt;/i&gt; easily as it does not possess dermal sclerites, has a large operculum, and a shell that is less vertically compressed, with a more circular aperture. The shell of &lt;i&gt;Gigantopelta&lt;/i&gt; may be coated in a layer of sulphide, which is frequent amongst vent gastropods including the neomphalins (Hickman, 1984; War&eacute;n &amp; Bouchet, 2001). &lt;i&gt;Gigantopelta&lt;/i&gt; is also comparable to the Oligocene fossil genus &lt;i&gt;Elmira&lt;/i&gt; Cooke, 1919, from a seep deposit near Bejucal, Cuba whose possible affinity to Neomphalina based on resemblance to &lt;i&gt;Chrysomallon&lt;/i&gt; was remarked upon by Kiel &amp; Peckmann (2007). Although the type species &lt;i&gt;Elmira cornuarietis&lt;/i&gt; Cooke, 1919, is approximately the same size as &lt;i&gt;Gigantopelta&lt;/i&gt; (&gt; 40 mm in shell length), it carries broad revolving grooves, which &lt;i&gt;Gigantopelta&lt;/i&gt; lacks. The true taxonomic affinity of &lt;i&gt;Elmira&lt;/i&gt; is still unclear.&lt;/p&gt;Published as part of &lt;i&gt;Chen, Chong, Linse, Katrin, Roterman, Christopher N., Copley, Jonathan T. &amp; Rogers, Alex D., 2015, A new genus of large hydrothermal vent-endemic gastropod (Neomphalina: Peltospiridae), pp. 319-335 in Zoological Journal of the Linnean Society (Zool. J. Linn. Soc.) (Zool. J. Linn. Soc.) 175 (2)&lt;/i&gt; on pages 322-323, DOI: 10.1111/zoj.12279, &lt;a href="http://zenodo.org/record/5338416"&gt;http://zenodo.org/record/5338416&lt;/a&gt