Parosphromenus kishii

First describ­tion:


Zootaxa 5061 (1): 071092

Char­ac­ter­is­tics: Parosphromenus kishii, sp. nov.,is dis­tin­guished from its con­geners by the fol­low­ing unique com-​bination of char­ac­ter­is­tics: the unique cau­dal fin col­oration, con­sist­ing of a uni­formly red­dish back­ground; irreg­u­lar faint turquoise blotches of dif­fer­ing sizes scat­tered on the cen­tral region of the cau­dal fin, vaguely form­ing a band with­out clear out­line; cau­dal fin pointed rhom­bic shape; a long dor­sal fin with XIIIXIV spines and 78 seg­mented rays (total 2022, mode 20); anal-​fin rays XIIXIII, 910 (total 2223, mode 22); a broad light bluish iri­des­cent band in dor­sal– and anal-​fin; pelvic fin and fil­a­ment uni­formly bluish.

Sim­i­lar species: Parosphromenus kishii can be eas­ily dis­tin­guished from all other Parosphromenus by its unique red­dish cau­dal fin with an irreg­u­lar faint turquoise pat­tern and pointed rhom­bic shape

Occurence/​Distribution: The species was recorded by H. Kishi in Kali­man­tan Ten­gah as early as Nov. 1999. Cur­rently it is only found in a sin­gle river, which is severely dis­turbed by human activ­i­ties (Fig. 6). Most of the nearby regions have been con­verted into oil-​palm plan­ta­tions. Thus, we have yet not been able to record this species out­side this sin­gle river. There are still some remote loca­tions with bet­ter poten­tial, which have not been explored in the last sur­vey. Fur­ther stud­ies will be nec­es­sary to clar­ify the dis­tri­b­u­tion of this endan­gered species.

Threat: Parosphromenus kishii sp. nov. is con­fined to a sin­gle river, which now func­tions as a nat­ural irri­ga­tion canal for a large oil-​palm plan­ta­tion. The habi­tat is extremely impacted. Any fur­ther works at the plan­ta­tion may lead to dredg­ing and expan­sion of this river, which may erad­i­cate the only known pop­u­la­tion of this species. Thus, fol­low­ing the IUCN Red List Cat­e­gories and Cri­te­ria (ver. 3.1), we pro­pose that this species be listed as Crit­i­cally Endan­gered B2ab (iii, v), based on its very restricted dis­tri­b­u­tion within a sin­gle river run­ning through an oil-​palm plan­ta­tion (<50 km2) with only a sin­gle known loca­tion and the extremely high like­li­hood of becom­ing extinct due to the poten­tial works of sur­round­ing oil-​palm plan­ta­tions. Imme­di­ate in-​situ or ex-​situ con­ser­va­tion is highly rec­om­mended for this species.

Discovery/​First import: The species was recorded by H. Kishi in Kali­man­tan Ten­gah as early as Nov. 1999




Dif­fer­ent forms of the cau­dal fin shape can be found within Parosphromenus kishii: a pointed rhom-​bic shape in most spec­i­mens (44 out of the 50 col­lected adult spec­i­mens), rhom­bic with a con­vex in the mid­dle in spe­cific spec­i­mens (2 out of 50) and lance­o­late with a pro­jected short fil­a­men­tous tip in cer­tain older adults (the me-​dian ray branched instead of sim­ple, 4 out of 50) (Fig. 7 A – C, G). Except the con­vex morph (Fig. 7 G), which might be an aber­rant one, other phe­no­types have been pre­served in the next gen­er­a­tion. We observed again in the same batch of F1 from a sin­gle pair, three dif­fer­ent morphs of cau­dal fin shapes: round, pointed rhom­bic and lance­o­late with a pro­jected short fil­a­men­tous tip (Fig. 7 D – F). The rays of the fin are not dam­aged in the exam­ined spec­i­mens, and these shapes are not aber­rant due to regrowth fol­low­ing injury. Thus, these dis­tinct cau­dal fin shapes are most likely a poten­tial poly­mor­phism in this species.

FIG­URE 7. (A) The rounded cau­dal fin of juve­niles: pos­te­rior edge of the fin smoothy rounded, not pointed; not pre­served; (B). The most com­mon rhom­bic caudal-​fin shape in adults, pos­te­rior edge of the fin pro­jected out­wards into a pointed rhom­bic shape, SJD KA2081, from type local­ity; ©. The third vari­ant of the caudal-​fin shape, the median ray branched and elon­gated into a short fil­a­ment in some adults, SJD KA2081, from type local­ity; (D) The rounded caudal-​fin shape in F1 adults (off­spring of the male in Fig. 5 C); (E) The pointed rhom­bic caudal-​fin shape in F1 adults (off­spring of the same clutch of the male in Fig. 5 C); (F) The spade-​shaded caudal-​fin shape with a short fil­a­ment (median ray branched) in F1 adults (off­spring of the same clutch of the male in Fig. 5 C); (G) Another vari­ant of the caudal-​fin shape in adults, the mid­dle part of the pos­te­rior edge of the cau­dal fin aber­rantly elon­gated out­wardly into a cen­ter con­vex rhom­bic shape, but with­out fil­a­ment; same fish with Fig. 5 C, not pre­served. (lat­er­ally inverted).


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