Periophthalmus magnuspinnatus Lee et al., 1995

Taxonomy - Identification - Distribution and Habitat - Ecology

Taxonomy

Periophthalmus magnuspinnatus Lee et al., 1995 has been long time misidentified in Chinese ichthyological literature as Periophthalmus cantonensis (Osbeck, 1765). For e.g. CHENG & ZHOU, 1997 list P. cantonensis inhabiting brackwater habitats in Chinese Shandong province. In fact, I don’t know one Chinese ichthyological book recognizing the valid status of P. magnuspinnatus. 

Periophthalmus magnuspinnatus from Qingdao/Shandong province/China

Vernacular name: Bèng Bèng Yύ 蹦蹦鱼 (Qingdao dialect, means Jumping Fish)

Identification

Periophthalmus magnuspinnatus is closely related to P. modestus Cantor, 1842. In some habitats both species occur sintopic on the mudflats. Hence, identification and differentiation of both species is a neccessary and helpful tool. I try to provide a differentiation key which is easy to understand and also useful when it comes to field identification. Attention, the key is only valid for living adult specimen. Preserved specimen may change colouration (BAECK et al., 2008; POLGAR G., 2008, email)

1. (2) Cheeks with big blue spots, D1 first spine elongated, D1 with conspicuous black band marginally, anal fin black                  .................................................................... Periophthalmus magnuspinnatus

2. (1) Cheeks with small white spots, D1 with much ligther band, anal fin transparent

..............................................................................Periophthalmus modestus

The blue spots on the cheeks of P. magnuspinnatus from Qingdao/Shandong province/China (Code: EW-CN 53-08) can be used for species determination.

Distribution and habitat

The mudskipper Periophthalmus magnuspinnatus is reported from South Korea (type locality), Chinese Bo Hai, Yellow, East and Southern coastlines. I remember a discussion with TANG Wenqiao from Shanghai Fisheries University in sommer 2006 about an occurence of P. magnuspinnatus close to Ningbo in Zhejiang province. At that time it was a new record. The definite distributional range is likely even more southern. The major problem in defining the boundaries of the distribution of P. magnuspinnatus is the very similar appearance and thus confusion with P. modestus and the misidentification as P. cantonensis in related Chinese literature (see taxonomy). 

Common to all mudskippers P. magnuspinnatus inhabits brackwater mudflats which are exposed at low tide. The mudflats usually have very slight slope. The larger the mudflats the more beneficial to the mudskippers lifestyle. In addition, the greater the dfiference between the water levels the better featuring vast expanses of exposed mudflats for the mudskippers to inhabit. Periophthalmus need mud to dig burrows for reproduction and wintering. 

Biotope EW-CN 53-08: Mudflats partially exposed at Qingdao. The picture on was taken on 2008-10-12 at 15:00 at roughly half low tide. The maximum water level line is quite conspicuous. Above this level the mud is dry and hard.

There is a waste (fresh) water outlet at posterior area. 

Ecology

As Periophthalmus magnuspinnatus lives on mudflats they are euryhaline and part of the intertidal ecosystem. They dig burrows for reproduction, hiding and wintering which are located in the upper section of an intertidal mudflat. So high that some high tide do not flood the burrows of P. magnuspinnatus. The J-shaped burrows have a depth of 25 cm and a simple structure (BAECK et al., 2008).

Periophthalmus magnuspinnatus is permanently foraging at water level line. They follow the water level lying on the mud chewing it. They seem to filter microorganisms out of the wet mud after the water retreated. When the body gets too dry they topple over one side to moisten the body with water, then toppling back. In case there is a wave they swim on the wave to the new water level and continue foraging. Generally their body is exposed more to the air than to the water. Hence, their activity is limited by the air temperature.  

Periophthalmus magnuspinnatus chewing mud in EW-CN 53-08.

Coexisting with Periophthalmus magnuspinnatus there is P. modestus. Pictures shows specimens of P. modestus rivalling in EW-CN 53-08 at sunset. Due to the difficult photographing circumstances the bright coloration and sharpness is impaired.

Actually both specimens show splendidly colorful coloration and pattern.

Marco Endruweit, 2008-10-13