DaLilFishie

Pacific White-sided Dolphin (Sagmatias obliquidens)

syn. Lagenorhynchus obliquidens
I always find it peculiar that Osaka’s dolphin tank is as small and faux-rock heavy as it currently stands. It really makes you wonder if an enclosure this subpar would be better off for a more size-appropriate species.

Also, based on the title, is Lagenorhynchus not a valid genus from your perspective?
 
@Austin the Sengi yes, I agree, this enclosure would me much better used for other species (ideally something actually found in the Tasman Sea, which this tank is intended to replicate despite its sole resident species not even being found there!).

As for the scientific name I used, as far as I know Lagenorhynchus is still a valid genus, but it has been split pretty heavily to the exclusion of obliquidens, which (along with some other former Lagenorhynchus) has been placed in the newly erected genus Sagmatias.
 
@Austin the Sengi I haven't read any literature on it, I'm just following a split made on iNaturalist
(Taxonomic Changes Taxon: Sagmatias (Active)" · iNaturalist Australia) splitting Lagenorhynchus into Lagenorhynchus sensu stricto (White-beaked Dolphin), Sagmatias (Peale's, Hourglass, Pacific White-sided and Dusky dolphins) and Leucopleurus (Atlantic White-sided Dolphin).

Not all authorities accept this split though - The Society for Marine Mammalogy's checklist still places all these species in Lagenorhynchus (Society for Marine Mammalogy)
 
This individual’s facial features resemble the Sea of Japan type (which may be recognized as a subspecies in the future).
 
@Veno how is the Sea of Japan type distinguished? Cetabase doesn't have any info on the origin of Osaka's dolphins so I can't confirm nor deny they originated from the Sea of Japan.
 
@Veno after having looked at that paper, I'd disagree that this specimen looks like the Sea of Japan type (morphotype 2 in the paper). Looking at figure 1 and my image, I think it looks more like morphotype 1 as the distance between the eye and front flipper is shorter than the distance as between the eye and tip of the snout (rather than the eye-snout distance being shorter than eye-flipper distance in morphotype 2) and the snout appearing more downcurved. If you disagree however I'd appreciate your input.
 

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Category
Osaka Aquarium
Added by
DaLilFishie
Date added
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Device
Panasonic DMC-FZ2500
Aperture
ƒ/4.1
Focal length
35.3 mm
Exposure time
1/125 second(s)
ISO
400
Flash
Off, did not fire
Filename
P1310023.JPG
File size
3 MB
Date taken
Mon, 07 April 2025 3:15 AM
Dimensions
5472px x 3648px

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