Sunday, February 4, 2018

[Ichthyology • 2014] Gymnochanda ploegi • A New Species of Ambassid Glassperch from West Kalimantan, Indonesia

Gymnochanda ploegi  Tan & Lim, 2014


 A spectacularly coloured sexually dimorphic freshwater glassfish allied to Gymnochanda verae is described herein. It shares with its other congeners a body without scales, but differing from its congeners with males having a maroon-red first dorsal fin, expanded maroon-red anal and second dorsal fins with black distal portions, without any individual fin ray elongations free from the interradial fin membranes; head with reddish opercle cover. A key to the genus Gymnochanda is also provided. 

Key words. Taxonomy, new species, Gymnochanda, sexual dimorphism, Southeast Asia 

 Species of Gymnochanda

Gymnochanda limi Kottelat, 1995
Gymnochanda filamentosa Fraser-Brunner, 1955
Gymnochanda flamea Roberts, 1994
Gymnochanda verae Tan & Lim, 2011
Gymnochanda ploegi, new species

Fig. 1. Gymnochanda ploegi: A, MZB 17220, 25.9 mm SL male holotype (note: anal fin is damaged); B, MZB 17221, 26.0 mm SL female paratype.

Gymnochanda ploegi, new species
Gymnochanda cf. flamea – Kottelat & Widjarnati, 2005: 164.  

Diagnosis. Gymnochanda ploegi can be differentiated from its congeners by the following characters: mature males with pinkish body with the dorsal half suffused with reddish pigments, expanded anal and second dorsal fins, the soft rays of both fins expanded to reach 2 /3 of caudal fin forming a crescentic profile, without any individual fin ray free from the interradial fin membrane; anterior part to whole of both anal and second dorsal fins maroon red in life, with posterior portion of distal rays black forming a crescentic pattern (hyaline when preserved); whole caudal fin lightly suffused with red in life (hyaline when preserved); female with yellowish body suffused with reddish pigments without any fin elongation (hyaline when preserved), both dorsal fins suffused with reddish pigments (hyaline when preserved).

Fig. 2. A, Gymnochanda verae – ZRC 53122, 22.3 mm SL male paratype, freshly dead specimen;
  BGymnochanda ploegi – MZB 17220, 25.9 mm SL male holotype, freshly dead specimen (note: anal fin is damaged);
CGymnochanda ploegi – MZB 17221, 26.0 mm SL female paratype, freshly dead specimen. 

Distribution. Gymnochanda ploegi is currently known from the Sanggau and Kapuas Lakes regions in West Kalimantan (Fig. 5).

 Habitat notes. As its congeners, this species inhabits still water pools near swamp forest and riverine systems. Apparently, this is the first import for the ornamental fish trade (August 2014) and it took the collectors more than three hours to trek to the site (A Meng pers. comm.). In the Kapuas Lakes region, G. ploegi could be sympatric with G. filamentosa; but they were not collected in the same sample from fish traps in a swampy area with brown water (M. Kottelat pers. comm.).

Etymology. This species is named in memory of Alex Ploeg, a good friend, fellow taxonomist, advisor and fellow conservationist against alien aquatic species; for his services to the ornamental fish trade in this region and abroad in his role as the Secretary General of the Ornamental Fish International; who unfortunately perished in a terrible tragedy over Ukraine on 17 July 2014.

Fig. 5. Map of Sundaland showing distribution of Gymnochanda: round = G. filamentosa; triangle = G. flamea; square = G. limi; inverted triangle = G. verae; and diamond = G. ploegi.

Tan Heok Hui and Kelvin Lim Kok Peng. 2014. Gymnochanda ploegi, A New Species of Ambassid Glassperch from West Kalimantan, Indonesia. RAFFLES BULLETIN OF ZOOLOGY. 62; 688–695.