deiss­neri

deissnerix

Kot­te­lat & Ng 1998

First descrip­tion: Valid today: Parosphromenus bin­tan, a new osphrone­mid fish from Bin­tan and Bangka islands, Indone­sia, with redescrip­tion of P. deiss­neri. Ichthy­olog­i­cal Explo­ration of Fresh­wa­ters, 8: 263272. – Until the pub­li­ca­tion of this new descrip­tion, the first descrip­tion was valid: P. Bleeker, Negende bij­drage tot de ken­nis der vis­chfau­na­van Banka. Natu­urkundig Tijd­schrift voor Ned­er­land­sch Indie, 18:359378.

The redescrip­tion with the approval of the nomen­cla­ture author­ity, ICZN, a cen­tury after its first descrip­tion, is very unusual, but nev­er­the­less fol­lows the reg­u­la­tions. The ICZN con­firmed this in the fol­low­ing pub­li­ca­tion: ICZN, 2000.Opinion 1946th Osphrone­mus deiss­neri Bleeker, 1859 (cur­rently Parosphromenus deiss­neri; Oste­ichtyes, Per­ci­formes): holo­type replaced by a neo­type. Bul­letin of Zoo­log­i­cal Nomen­cla­ture, 57 (1): 60

Back­ground: in the nine­teen nineties it was already clear that the orig­i­nal view, there was only one Parosphromenus species, had been wrong. It was also obvi­ous that the licorice gouramis, found up to that date and usu­ally labelled as “P. deiss­neri”, must have belonged to dif­fer­ent species. There­fore there was an inter­est to exam­ine Bleeker’s orig­i­nal fish (one spec­i­men) again in the light of this new find­ings. When Kot­te­lat and Ng did so, quickly three things became clear. First, the spec­i­men was in very poor con­di­tion. Sec­ond it was a female and thus lacked impor­tant species dif­fer­en­ti­a­tion char­ac­ter­is­tics; such as colours, which barely remain in the con­served state. Third, by this time it was already known that at least two dif­fer­ent Parosphromenus species exist on Bangka, which can be dis­tin­guished struc­turally by the shape of their tail fin. The cau­dal fin would have been an impor­tant struc­tural dif­fer­en­ti­a­tion char­ac­ter­is­tic, but the spec­i­men lacked this. Mean­while, because the old holo­type could no longer be used to decide which of the two Bangka species really is deiss­neri, the two ichthy­ol­o­gists requested to assign a neo­type and to describe the species on this basis. This pro­posal was accepted. In this case it was decided that not the species with the round tail fin, but the other with a clear fil­a­ment in its tail fin would be (deiss­neri). (Remark PF: If the deci­sion had been taken to select the other species, much of the con­fu­sion about the species´ name could have been avoided. But it is now idle to spec­u­late about it). The other, round finned species was then described as P. bin­tan, because it occurs on the island Bin­tan as well.

Char­ac­ter­is­tics: Over­all length max. 5 cm, mak­ing it one of the largest licorice gouramis. Dor­sal struc­ture: XII-​XIII, 6, total 1819, Anal: XII-​XIII, 810, total 2123. ♂ in nup­tial plumage struc­turally well iden­ti­fi­able by the tri­an­gu­lar, up to one cen­time­ter long black cau­dal fil­a­ment. Addi­tion­ally it is very char­ac­ter­is­tic that the light pat­terns in the unpaired fins are not con­tin­u­ous, but sin­gle short light bands. Espe­cially in the cau­dal fin this char­ac­ter­is­tic is very obvi­ous, as the lines located there have a hor­i­zon­tal and nearly par­al­lel off­set. P. deiss­neri males are there­fore among the most eas­ily rec­og­niz­able licorice gouramis (see illustration).

Sim­i­lar species: the risk of con­fu­sion with other licorice gouramis is low for the males, due to the phe­no­typic dif­fer­en­ti­a­tion, which is based on struc­tural (cau­dal fin with dis­tinct black fil­a­ment) dif­fer­ences and on the char­ac­ter­is­tic colour pat­terns. For the females the risk is higher; here the (less obvi­ous) dif­fer­ences in physique have to be con­sid­ered. How­ever it has to be pointed out again that the per­ma­nence of using the his­toric name until 1998 for var­i­ous kinds of licorice gouramis, still con­fuses large parts of the aquar­ium hobby, although, at least for the males, a dif­fer­en­ti­a­tion is almost no prob­lem. Not only in the trade, but also in many inter­net pub­li­ca­tions and in un-​specialised gen­eral aquar­ium arti­cles and books,this wrong des­ig­na­tion still occurs almost unabated.

Occurence/​Distribution: fol­low­ing the first descrip­tion, deiss­neri is endemic on the Malayan island Bangka, but has been found later on the neigh­bour island Beli­tung as well. Obvi­ously it has not spread further .

Threat: Due to the restric­tion of occur­rence on these two islands the threat is very high.

Discovery/​First import:

Trade: as already men­tioned, it is still almost impos­si­ble to dis­en­tan­gle the name and iden­ti­fi­ca­tion con­fu­sion in the inter­na­tional trade. Only grad­u­ally have the exporters and importers realised that there was this new descrip­tion, which for­bids the iden­ti­fi­ca­tion of most of the licorice gouramis, offered in trade, as deiss­neri. Unaf­fected by this, many of the licorice gouramis are still incor­rectly traded as deiss­neri. How­ever, until a few years ago, real P.deissneri have obvi­ously never been traded. Only recently have there been few imports to Europe or Amer­ica, but due to the name con­fu­sion these fish have soon dis­ap­peared and were lost in the total­ity of traded licorice gouramis, before spe­cial­ists could get hold of them. The aquar­ium strains, swim­ming today in a few tanks, go back to pri­vate imports (e.g. Kopic, Brown, ).

Care /​Breed­ing: No spe­cial con­di­tions that devi­ate from the usual Paros water stan­dards are required. How­ever, note that deiss­neri is one of the largest and strongest licorice gouramis. There­fore, they should not be kept in the small­est tank. In the long run, a 12-​liter tank would be too small and a 25-​liter tank would be the min­i­mum. The nests can be large (over 100 eggs, but usu­ally less).

Behaviour/​Particularities: no par­tic­u­lar­i­ties. Hor­i­zon­tal to head down courtship. Often with very dis­tinct foam nest, some­times only rudi­men­tary nest. Large deiss­neri belong to the most impres­sive forms we know.

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