Blind cave gudgeon

Milyeringa veritas

FAMILY

Eleotridae

TAXONOMY

Milyeringa veritas Whitley, 1945, Milyering, Yardie, 20 mi (32 km) southwest of Vlamingh Head, North-West Cape, Western Australia. Populations show a low degree of heterozygosity, which is typical of cave-dwelling fishes. This species is possibly closely related to the Indo-Pacific eleotrid genus Butis.

OTHER COMMON NAMES

English: Cave gudgeon.

PHYSICAL CHARACTERISTICS

Reaches about 2 in (5 cm) total length. The head is broad and concave over the snout. The eyes are not visible. Small first dorsal fin with four very short spines. Second dorsal fin with nine longer rays. Pelvic fins separate. The caudal fin is slightly pointed. The head is naked but the body is covered with small scales (about 28 in series along the flanks). The fish is very poorly pigmented. The top of the head is pale yellow, with a dark gray triangular mark over the brain. The posterior nostrils are pink. There is a purplish spot over the operculum. The body is pale gray and fins are flesh colored.

DISTRIBUTION

Western and northeastern coastal plains of the Cape Range Peninsula and Barrow Island, Western Australia.

HABITAT

This is a troglobitic species; i.e., an obligatory cave dweller, found in shallow wells (at depths of up to 1.6 ft/0.5m), sink-holes,

and deeper cave systems (at depths of up to 105 ft/32 m) that are freshwater or anchialine (located near the sea and flooded with sea water). In anchialine systems the fishes may live in freshwater layers that overlie the salt water. They are also found in brackish water, tolerating salinities from 0.27–34 parts per thousand and temperatures of 70–83°F (21–28°C).

BEHAVIOR

Swims slowly, with the pectorals pointed out to the sides and the pelvics extended slightly forward.

FEEDING ECOLOGY AND DIET

Possibly feeds on insects or other small animals that drop into the cave waters.

REPRODUCTIVE BIOLOGY

Random mating apparently occurs between subpopulations throughout the range.

CONSERVATION STATUS

Listed as Data Deficient in the IUCN 2002 Red List, but as threatened by the Western Australian Conservation Act. Major threats come from habitat disturbance due to urban and agricultural development, and water extraction causing a lowering of the water table. Water quality in the underground systems is being compromised by pollution from nutrients and other chemicals.

SIGNIFICANCE TO HUMANS

None known.