| Summary: | Modiolus cimbricus sp. nov. urn:lsid:zoobank.org:act: FA5D6226-648B-44C5-A5BE-1E4D0F97BA67 Figs 1–2 Mytilus adriaticus – Petersen 1888: 126. Modiola adriatica – Petersen 1893: 71. — Jensen & Spärck 1934: 75. — Jørgensen 1946: 288. Modiolus adriaticus – Muus 1973: 84. — Rasmussen 1973: 272. — Christensen 1978: 49. — Wikander 1981: 73. — Bondesen 1984: 13. — Larsen et al . 2007: 425. Diagnosis Dissoconch shell substance thin and light. Shell shape in lateral aspect somewhat elongated, anteroventrally upturned often approaching a parallelogram, dorsal margin behind umbones straight in adult specimens; shell margin postero-dorsally stretched and narrowly rounded posteriorly, mid-ventrally straight or nearly so. Umbones strongly prosogyrate not much elevated above the dorsal margin. Shell surface with sharp growth lines and often with low and uneven commarginal ribs. Periostracum yellowish and varnished turning brownish in larger specimens. Short and simple byssal hairs on the periostracum occur mainly around the siphonal region. They are easily lost just as are grains glued to the shell. Shell inside glossy, neither adductor muscle scars nor pallial line are discernible. Ligament is sub-internal, not strong and its length between 35–40% of the adult shell length. The prodissoconch I is 400 µm. The species is edentulous after the nepioconch stage. The nepioconch usually turns whitish when it remains in adult specimens. Largest diameter of nepioconch is most often between 0.6–0.8 mm. Shell colouration varies greatly. Red only, red with blue (violet or purple), blue only, and presence of opaque white, usually as blotches, or absence of white. Red is by far the most common colour expressed as rays, strongest dorsally and posteriorly on the shell. Uncoloured specimens appear to be very rare. A well-developed bundle of byssus, strong, hair-like protein threads, originate from the posterior end of the foot and are used for attachment to sandgrains that form a covering around the shell. This species is referred to the ...
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