Gigantopelta chessoia, Chen & Linse & Roterman & Copley & Rogers, 2015

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), Zoological Journal of the Linnean Society (Zool. J. Linn. Soc.) 175 (2), pp. 319-335 : 323-327

publication ID

https://doi.org/10.1111/zoj.12279

DOI

https://doi.org/10.5281/zenodo.10543351

persistent identifier

https://treatment.plazi.org/id/0F16272F-FFD4-FFEB-2C15-927CFBDEF9FE

treatment provided by

Felipe (2021-08-28 20:40:51, last updated 2024-11-28 04:20:31)

scientific name

Gigantopelta chessoia
status

sp. nov.

GIGANTOPELTA CHESSOIA View in CoL SP. NOV. ( FIGS 2–7 View Figure 2 View Figure 3 View Figure 4 View Figure 5 View Figure 6 View Figure 7 )

‘Peltospiroidea n. sp. ’ – Rogers et al., 2012: 7, fig. 3d. ‘Undescribed species of peltospiroid gastropod’ – Marsh et al., 2012: 6, fig. 5c, j.

Type material

Holotype. Shell diameter 36.30 mm, 99% ethanol, Figure 3A–C. E View Figure 3 2 View Figure 2 segment, East Scotia Ridge, 56°05.31′S, 30°19.10′W (‘Cindy’s Castle’), 2606 m deep, RRS James Cook expedition JC42, ROV Isis Dive 130, 20.i.2010, leg. A. D. Rogers ( NHMUK 20150066 About NHMUK ) GoogleMaps . Paratypes. One dissected specimen, 99% ethanol (shell diameter 31.12 mm, Fig. 4A, B View Figure 4 ; NHMUK 20150067 About NHMUK ) ; growth series of five specimens, 99% ethanol ( NHMUK 20150068 About NHMUK ) . 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 About NHMUK ) GoogleMaps . Collection data for the latter three lots: E2 segment, East Scotia Ridge, 56°05.34′S, 30°19.07′W (‘ Cindy’s Castle’), depth 2644 m, RRS James Cook expedition JC42, ROV Isis Dive 134, 24.i.2010, leg. A. D. Rogers. GoogleMaps

Other material examined

Approximately 200 specimens collected on RRS James Cook expedition JC42 with ROV Isis , 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°02.81′S, 29°58.71′W (‘Marsh Tower’), depth 2394 m, RRS James Cook expedition JC42, ROV Isis Dive 141, 30.i.2010, leg. A. D. Rogers.

Etymology

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.

Zoobank registration urn:lsid:zoobank.org:act:D46EB848-506D-45B7-8D05-35535592BD1E

Description/Diagnosis

Shell: Shell ( Fig. 4A, B View Figure 4 ) 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 View Figure 5 ) consists of 0.5 whorls, diameter about 210 μm. 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.

Operculum: Operculum ( Fig. 3C View Figure 3 ) with central nucleus, multispiral, thin, flaky on fringe. Operculum fringe often damaged. Juveniles operculum thin, semitransparent, fringe not flaky ( Fig. 5C View Figure 5 ).

Radula: Radula ( Fig. 6A View Figure 6 ) rhipidoglossate. Ribbon approximately 0.5 mm wide and 4 mm long in adults. Formula ∼50 + 4 + 1 + 4 + ∼50. Central, lateral teeth cusp-like, pointed ( Fig. 6C View Figure 6 ). Marginal teeth long, slender, bearing ∼20 denticles at distal end ( Fig. 6E View Figure 6 ). Central tooth triangular, very broad at base, tapering dis- tally, smooth, no sculpture. Lateral teeth solid, bearing a clear protrusion at base.

Soft parts ( Fig. 7A View Figure 7 ): 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.

Distribution

Only known from hydrothermal vents on segment E2 (56°05.2′S to 56°05.4S, 30°19.00′W to 30°19.35′W) and E9 (60°02.50′S to 60°03.00′S, 29°58.60′W to 29°59.00′W) of ESR. This species forms dense aggregations rather close to vent effluents.

Remarks

The dispersal mechanism is inferred to be nonplanktotrophic from the protoconch, presumably with a planktonic dispersal stage. Table 2 shows the shell parameters of G. chessoia . The relationships between the six shell parameters measured were investigated and they were all linear across all life stages. Figure 8 View Figure 8 shows a scatter plot of shell diameter against shell height. See Rogers et al. (2012) for details on location of hydrothermal vent sites.

Comparative remarks

Similar to Gigantopelta aegis sp. nov. described below. Gigantopelta chessoia can be distinguished as it has a taller spire, less extensive callus, and area around callus is concave and not flattened as in G. aegis . Differences are seen in the structure of the radula. The central tooth of G. chessoia is much wider at the base and triangular compared with that of G. aegis , which is rectangular. Lateral teeth are sculptured in both species, but the marks occur nearer to the base of the teeth in G. aegis . Gigantopelta chessoia can also be easily distinguished by the lack of sulphide deposits on the shell and operculum, at least from G. aegis found in Longqi Field, the only known habitat to date. Similarly, the operculum in G. aegis is much thicker than G. chessoia at all life stages.

Marsh L, Copley JT, Huvenne VAI, Linse K, Reid WDK, Rogers AD, Sweeting CJ, Tyler PA. 2012. Microdistribution of faunal assemblages at deep-sea hydrothermal vents in the Southern Ocean. PLoS ONE 7: e 48348.

Rogers AD, Tyler PA, Connelly DP, Copley JT, James R, Larter RD, Linse K, Mills RA, Garabato AN, Pancost RD, Pearce DA, Polunin NVC, German CR, Shank T, Boersch-Supan PH, Alker BJ, Aquilina A, Bennett SA, Clarke A, Dinley RJJ, Graham AGC, Green DRH, Hawkes JA, Hepburn L, Hilario A, Huvenne VAI, Marsh L, Ramirez-Llodra E, Reid WDK, Roterman CN, Sweeting CJ, Thatje S, Zwirglmaier K. 2012. The discovery of new deep-sea hydrothermal vent communities in the Southern Ocean and implications for biogeography. PLoS Biology 10: e 1001234.

Gallery Image

Figure 2. In-situ aggregations of the two new species of Gigantopelta gen. nov.: A, Gigantopelta chessoia sp. nov. at E2 segment, East Scotia Ridge; B, Gigantopelta aegis sp. nov. at Longqi vent field, South West Indian Ridge. Scale bars = 5 cm.

Gallery Image

Figure 3. A−C, Gigantopelta chessoia sp. nov., holotype (NHMUK 20150066): A, aperture view; B, umbilical view; C. aperture view; D−F, Gigantopelta aegis sp. nov., holotype (NHMUK 20150070): D, aperture view; E, umbilical view; F, aperture view. Scale bars = 1 cm. Photography by Pete Bucktrout (British Antarctic Survey).

Gallery Image

Figure 4. A, B, Gigantopelta chessoia sp. nov., paratype shell (NHMUK 20150067): A, aperture view; B, abaperture view. C, D, Gigantopelta aegis sp. nov., paratype shell (NHMUK 20150071): C, aperture view; D, abaperture view. Scale bars = 1 cm. Photography by Pete Bucktrout (British Antarctic Survey).

Gallery Image

Figure 5. Protoconchs: A, Gigantopelta chessoia sp. nov., scale bar = 100 μm; B, Gigantopelta aegis sp. nov., scale bar = 100 μm. Juvenile operculum: C, G. chessoia sp. nov., scale bar = 500 μm; D, G. aegis sp. nov., scale bar = 500 μm.

Gallery Image

Figure 6. Radula. Overview: A, Gigantopelta chessoia sp. nov.; B. Gigantopelta aegis sp. nov.; scale bars = 100 μm. Central and lateral teeth close-up: C, G. chessoia sp. nov.; D, G. aegis sp. nov.; scale bars = 20 μm. Marginal teeth close-up: E, G. chessoia sp. nov.; F. G. aegis sp. nov.; scale bars = 10 μm.

Gallery Image

Figure 7. Illustration of soft parts with the mantle partially removed: A, Gigantopelta chessoia sp. nov.; B, Gigantopelta aegis sp. nov. Scale bars = 1 cm. Abbreviations: ct, ctnidium; dg, digestive gland; eg, oesophageal gland; et, epipodial tentacles; f, foot; gd, gonad; ll, lateral lappet; o, operculum attachment; pc, pericardium; sn, snout; t, cephalic tentacles.

Gallery Image

Figure 8. Scatter plot of shell diameter vs. shell height across a size range of 100 specimens: A, Gigantopelta chessoia sp. nov. (line of best fit formula: y = 0.9045x −0.6278, R2 = 0.99); B, Gigantopelta aegis sp. nov. (line of best fit formula: y = 0.8823x −0.8362, R2 = 0.99).

ZC

Zoological Collection, University of Vienna

CAMZM

University Museum of Zoology, Cambridge

SMNH

Department of Paleozoology, Swedish Museum of Natural History

Kingdom

Animalia

Phylum

Mollusca

Class

Gastropoda

Order

Neomphalida

SuperFamily

Neomphaloidea

Family

Peltospiridae

Genus

Gigantopelta