Vulcanidas
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| by Cosel & Marshall , 1985 |
Vulcanidas is a genus of "deep-sea mussels" from the family of blue mussels ( Mytilidae ). The only recent species feeds on symbiotic sulfur bacteria in the gills, but also by filtering .
features
The cases are up to 18 cm long and 9.2 cm high; the length-width ratio is between 1.8 and 2 in adult specimens. the outline is somewhat variable. The dorsal edge is usually angled, but can also be "only" rounded. The maximum height (tip of the angle) is in the middle third of the case, but clearly behind the middle, i.e. slightly shifted towards the rear edge. The rear edge is broadly rounded, the front edge slightly more rounded. The vertebrae sit near the front end, about a tenth of the total length. The shell is comparatively thin but has a firm shell. The surface shows concentric growth lines, which in some specimens can be a little coarser. The periostracum is mostly black, occasionally also brownish-black, reddish-brown to reddish. The inside is white and iridescent. The anterior and posterior sphincters are comparatively large. The posterior sphincter is not divided into individual strands. The surface line runs very close to the edge of the case on the ventral edge. The Prodissoconch I is typically D-shaped with a length of 130 µm.
The gills are very long and not hypertrophied. They contain endosymbiotic , thiotrophic bacteria. The foot is short and small. The digestive tract is well developed. The midgut is wrapped in a single, very long loop. The anterior foot / byssus retractor muscle is short and very wide, and inserts on the shell in the middle to posterior part of the vertebral chamber. The rear foot retractor is well developed. The posterior byssus retractor is very wide and consists of numerous diverging muscle bundles with a common base on the byssus . The posterior retractor muscle forms a uniform scar on the shell; a separation into an anterior and posterior muscle area is not observed.
Similar genera
The gills of Vulcanidas are, like other deep-sea mussels, very long, but less fleshy and hypertrophied like z. B. Bathymodiolus and Gigantidas species. The midgut is placed in a large loop; in other deep-sea mussels the loop is much smaller or absent.
Geographical distribution and habitat
The only recent species has so far only been known at two locations on the Kermadec Ridge, northeast of New Zealand, the Macauley volcanic crater (30 ° 12.86 ′ S; 178 ° 27.01 ′ W) and the Giggenbach volcano (30 ° 2.02 ′ S ; 178 ° 42.65 ′ W). The water depth there is between 140 and 504 meters.
The animals feed on the one hand on the symbiotic sulfur bacteria in the gills, but on the other hand also by filtering. When examining the digestive tract it turned out that the intestine z. T. was filled with detritus. The small D-shaped Prodissoconch I indicates a planktotrophic development.
Taxonomy
The taxon was first described in 2010 by Rudo von Cosel and Bruce Marshall. Steffen Kiel and Amano presented a fossil species from the Middle Eocene from the west coast of North America, but with question marks about the genus Vulcanidas . Cosel and Marshall assigned the genus to the subfamily Modiolinae; they considered the Bathymodiolinae to be synonymous with the Modiolinae. Thubaut et al. (2013), however, (again) understood the subfamily Bathymodiolinae as a valid subfamily and transferred Vulcanidas to the subfamily Bathymodiolinae.
- Vulcanidas? goederti Kiel & Amano, 2013 (Middle Eocene , Palaeogene)
- Vulcanidas insolatus Cosel & Marshall, 2010
literature
- Rudo von Cosel, Bruce A. Marshall: A new genus and species of large mussel (Mollusca: Bivalvia: Mytilidae) from the Kermadec Ridge. Tuhinga: Records of the Museum of New Zealand Te Papa Tongarewa, 21: 59-73, 2010 PDF
- Steffen Kiel, Kazutaka Amano: The Earliest Bathymodiolin Mussels: An Evaluation of Eocene and Oligocene Taxa from Deep-Sea Methane Seep Deposits in Western Washington State, USA. Journal of Paleontology, 87 (4): 589-602, 2013 doi : 10.1666 / 12-135
- Justine Thubaut, Nicolas Puillandre, Baptiste Faure, Corinne Cruaud, Sarah Samadi: The contrasted evolutionary fates of deep-sea chemosynthetic mussels (Bivalvia, Bathymodiolinae). Ecology and Evolution, 3 (14): 4748-4766, 2013 doi : 10.1002 / ece3.749