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From: Dr Rick Webber Te Papa
_: 5
Date: 09-08-10
Time: 17:57
[Basically Rick is explaining, the shrimps we have had on this site of recent, from B.O.P., B.Is and P.K., are all Rhynchocinetes sp. Wade}
Dear Wade,
I attach some of the photos you sent me. The first (05 saran shrimp) was taken from a video and from the Poor Knights. Not a very clear shot but I'm sure it is Rhynchocinetes sp. because of the obviously large rostrum with white along the underside.
The second one, put on your site by Ursula Buckingham (DSCF7793) is also Rhynchocinetes sp. Again it is the large rostrum with its white toothy underside.
The 3rd from Julia Riddle on your site, is also Rhynchocinetes (there is another front-on photo of the same species from Julia and you also sent me a similar shot by Ian Skipworth - neither included here).
They are all Rhynchocinetes sp. because of the large size of the rostrum with its prominent, toothed, white underside. The two front-on shots are beautifully clear about the row of teeth under the rostrum and also show the inner edge and tip of the antennal scale on each side of it are white too. In addition, the tip of the rostrum has 3 - 4 teeth on it and is dark red. I think the size and whiteness coupled with the rostrum being able to move up and down, probably contribute to the shrimp signalling to 'clients' that it is keen to clean.
The pattern of spots and stripes is not all that different between photos 'DSCF7793' and 'red shrimp 2'. However, two species of Rhynchocinetes have been found in NZ, R. balssi and R. ikatere . Which of these two the photos represent I do no know. I would need to examine animals under a microscope to establish that. The front-on photos indicate clearly that the tips of the chelae (pinchers) are dark. This is a characteristic of R. ikatere but may also be present on R. balssi.
One thing I'm pretty certain about is that it is not Lysmata morelandi. In Rhynchocinetes species, the rostrum is about as long as the whole carapace but in L. morelandi it is hardly half as long as the carapace. It also has only two teeth on the underside of the rostrum (but it does have a row of good sized teeth along the top which continues along the carapace, halfway to its back edge. Nor is the rostrum of L. morelandi hinged; it is continuous with the carapace.
One difficulty we have with some of these shrimp species is that we have no good illustrations, particularly of L. morelandi. This is something that I or someone needs to address. We may well get good pictures, including some excellent photos such as those you have sent me, in the Steve Cook book on Coastal Inverterabtes of NZ (1st edition published, second edition on its way).
I hope that has helped.
Cheers, Rick
Last changed: 23-Jul-2011