Additions to the identification and distribution of the flatfishes in

Russian North Pacific Elena Voronina

Boris Sheiko Laboratory of Ichthyology

Zoological Institute, Russian Academy of Sciences

Order Pleuronectiformes (Nelson, 2006)

The pleuronectids are present in the Arctic Ocean seas as well as in adjacent boreal waters.Among them

Acanthopsetta nadeshnyiAtheresthes evermanni, A. stomiasHippoglossoides elassodon, H. robustusLimanda aspera, L. sakhalinensisPlatichthys stellatusLiopsetta glacialis, L. pinnifasciataReinhardtius hippoglossoides

are the subject of the present report

Acanthopsetta nadeshnyiBoreal Pacific

Although the findings in the Bering Sea were reported, reliable ones are only two specimens caught in 80-es off southwest Kamchatka (possible introduction of eggs). There are 76 inventored lots of this species in the collection of ZIN RAS. Five of them caught in the Bering Sea have been reidentified as Limanda sakhalinensis. Thus, all specimens of Acanthopsetta nadeshnyi are from Japan, Okhotsk, Yellow Seas and Pacific ocean off Japan

Head of

Acanthopsetta nadeshnyi

Limanda sakhalinensis

3 or sensory pores2

scales

Genus Atheresthes long thought to be closely related to Reinhardtius and included into the latter one.Our morphological data, e.g. plesiomorphies in the lateral line system of the head, support validity of Atheresthes and its basal position in pleuronectid phylogeny

Atheresthes Reinhardtius

That corroborates the results of examination of sequence data of the mitochondrial cytochrome b in flatfishes (Suzuki et al., 2001)

Sympathric Boreal Pacific species. The new diagnostic characters and redetermination of the specimens are required to precise distribution.

Atheresthes evermanni Atheresthes stomias

Hippoglossoides elassodon Boreal Pacific

Hippoglossoides robustusArctic–boreal Pacific

The distribution of these species in the Strait of Tartary, Bristol Bay, near Kamchatka, is questionable due to often misidentification.Identification is complicated by overlapping morphometric. New reliable differences (e.g. in length of upper jaw, rows of scales etc.) should precise their differentiation.

Limanda sakhalinensis Limanda aspera

Sympathric species, both boreal Pacific. The adults are easily distinguished by the scales, but in juveniles these characters are undeveloped.

Limanda sakhalinensis

Limanda aspera

Lateral line

Genus Liopsetta: taxonomic status has been in question in recent years.Substantial differences between Liopsetta and Pleuronectes have been revealed, the main is unique for pleuronectids reduction of infraorbital sensory canal.

L. glacialis P. quadrituberculatus

Our morphological data together with data of molecular biology support validity ofand its independence from

Original cladogram

Roje, 2010

Liopsetta

Pleuronectes

Liopsetta glacialis Arctic

Liopsetta pinnifasciata Boreal Pacific

Pleuronectes quadrituberculatus boreal Pacific

Including Liopsetta species into Pleuronectes makes the latter genus distribution Arctic Boreal, which is incorrect.

Platichthys stellatus Arctic Boreal Pacific

Extremely wide distribution and the differences between populations are the presumption of two species existence. It requires extensive morphological study supported by molecular analysis.

Reinhardtius hippoglossoidesArctic Boreal Pacific and Atlantic, amphiboreal

Conclusion

These examples demonstrate that using pleuronectid distribution for the investigation of the biodiversity and climate change effect monitoring as well as evolution of the group require:

1.Accuracy of the different rank taxonomy – family (Pleuronectidae), genus (e.g. Pleuronectes).

2.Accuracy of the identification and redetermination of the specimens (Acanthopsetta, Hippoglossoides species)

3.Revision of taxa (Platichthys, Reinhardtius) supported by molecular analysis.

Thank you for your attention!