New archaeogastropod limpets from hydrothermal vents: new family Peltospiridae, new superfamily Peltospiracea

Abstract

Seven new species of limpets from hydrothermal vents are described in five new genera in the new family Peltospiridae (new superfamily Peltospiracea). Limpets in this family are known only from the hydrothermal vent community at two sites, near 21°N and 13°N, on the East Pacific Rise. New genera and species are: Peltospira, type species P. operculuta from both sites, and P. delicata from 13°N; Nodopelta, type species N. heminoda from both sites, and N. subnoda from 13°N; Rhynchopelta, type species R. concentrica from both sites; Echinopelta, type species E. fistulosa from 21°N; Hirtopelta, type specics H. hirta from 13°N. These limpets are associated with the Pompei worm Alvinella, except for Rhynchopelta, which is associated with the vestimentifcran worm Riftia.

Habitat Associations in Gastropod Species at East Pacific Rise Hydrothermal Vents (9°50′N)

“…well defined because of the difficulty of measuring conditions inside their tubes (e.g., Chevaldonné et al, 2000), but the absence of Alvinellid group species in the diffuse flows of up to about 25°C that support vestimentiferan colonies suggests an association with higher temperatures or other environmental factors rarely found outside the alvinellid zone. This observed association between peltospirids and alvinellid habitat is consistent with prior collections for taxonomic studies (e.g., McLean, 1989;Bouchet, 1989, 1993), although specimens of Peltospira and Nodopelta are occasionally found in vestimentiferan clumps or mussel beds (Van Dover, 2003;Govenar et al, 2005) and may be exploiting microhabitats there with atypically high concentrations of vent fluid. In contrast, Pachydermia laevis has been reported consistently from collections of tubeworms and bivalves as well as alvinellids Bouchet, 1989, 1993), and likely has broader habitat associations than the peltospirids.…”

Larval dispersal between hydrothermal vent habitats

“…The protoconch of P. operculata appe~rs identical to the larval shells found at 9°N. Adult specimens of P. delicata tend to lose their protoconchs (McLean 1989a), though the scar left on the adult shell indicates that the protoconchs are the same size as the larval shell s found in the present study . A third congener, P. lamellifera, has been found along the East Pacific Rise, though not at 9°N.…”

“…One other species, Nodopelta subnoda, has a protoconch that appears similar to the larval specimens, but the correspondence in morphology is not as exact as that of P. operculata. Because P. operculata has been found Lutz et al 1986, McLean 1989aTurner et al 1985, McLean 1989a at 9°N, and the protoconch is so similar to the larval shells, these larvae were identified as P. ?operculata.…”

Two New Hot-Vent Peltospirid Snails (Gastropoda: Neomphalina) from Longqi Hydrothermal Field, Southwest Indian Ridge

“…This is interesting as Provannidae is the only gastropod family other than Peltospiridae known to house chemosynthetic symbionts intracellularly (Sasaki et al, 2010), and indicate that both families likely succeeded in chemosynthetic ecosystems by diversifying into both symbiotic and non-symbiotic feeding niches. Although neomphalines are highly diverse and more than 10 genera across all three families Neomphalidae, Peltospiridae, and Melanodrymiidae co-occur in East Pacific Rise and nearby areas (McLean, 1989;Warén and Bouchet, 2001;Heß et al, 2008), the present work presents the first record of giant holobiont peltospirids (Chrysomallon and Gigantopelta) co-occurring with other, non-chemosymbiotic peltospirids. Prior to the present study, the two holobiont genera were the only neomphalines reported from East Scotia Ridge and Indian Ocean vents where they occur (Rogers et al, 2012;Chen et al, 2015a,c;Copley et al, 2016).…”