Science News: Siluridae - Pterocryptis buccata

[Silurus]

Synopsis by Shane Linder

A recent paper by Ng Heok Hee and Maurice Kottelat describes Southeast Asia's first cave catfish.

During the French Thai-Maros expedition in 1986, a species of blind cave loach (now described as Nemacheilus troglocataractus, Kottelat and Gery, 1989) was collected from the Sai Yok Noi cave in Kanchanaburi Province, Thailand. The expedition also found an unpigmented catfish of the genus Pterocryptis. Since that discovery, a normal, epigean species has been found in the surrounding area. Based on the limited number of samples from both the cave and surface species, the authors choose to describe both forms as one new species.

The holotype is a male measuring 95.6 mm SL and among the two paratypes is another male measuring 146.6 mm SL. Pterocryptis buccata differs from all other Pterocryptis by its mandibular muscles that are prominent enough to make the fish appear to have puffy cheeks. The fish has four barbels and seven pelvic-fin rays. The fish are sexually dimorphic with the male having a thickened pectoral spine. The male's pectoral spine also has prominent serrations on the posterior edge of the spine. This form of sexual dimorphism is common among many silurids.

So far, this species has only been recorded from Sai Yok District in the Meklong basin of western Thailand. The hypogean, or cave, population is unpigmented and the body is an overall cream color. The fish is not eyeless, however, and does possess small eyes that are covered by skin. The underground stream in which the cave population was found contained a high CO2 concentration. The temperature was 24.5°C (about 76°F) with a pH of 6.25, a total hardness of 22.6 dH, and a carbonate hardness of 21.2 dH.


Reference: HH Ng & M Kottelat, 1998. Pterocryptis buccata, a new species of catfish from western Thailand (Teleostei: Siluridae) with epigean and hypogean populations. Ichthyological Research 45: 393-399.