The clockwork olive: Perspectives from the “American Shoulder”
In: The Festivus: A publication of the San Diego Shell Club. San Diego Shell Club: San Diego. ISSN 0738-9388, more
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| Keywords |
Americoliva Petuch, 2013 [WoRMS]; Oliva mustelina Lamarck, 1811 [WoRMS]
Marine/Coastal |
| Author keywords |
“American Shoulder” patterns, “Chevron Paradigm” |
| Abstract |
The structure and the biological significance of the Olivinae fasciculate ornamentation known as “American Shoulder” (after its presence in the American olives) are investigated for around 20 Western Atlantic / Gulf of Mexico / Caribbean species. The applicability of the “Chevron Paradigm” by Tursch & Greifeneder (2001) to the subchannel area is questioned and contrary evidence is proposed. A robust correlation between lip thinning phases and the generation of the typical American Shoulder features is observed: their coincidence with rapid growth stages as reported by Strano (2017) is plausible but wasn’t established decisively in absence of destructive investigations. The issues of intraspecific and interspecific variability are addressed thanks to an extensive photographic coverage, and a new general description of the peculiar pattern emerges from the investigations. The initial identification of some specimens included in this study is questioned on the basis of their subchannel pattern, hinting at its possible use as an accessory character in species determination, and suggesting to include exhaustive descriptions of American Shoulder patterns in new nomenclatural acts involving the (sub)genus Americoliva. |
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