The pygmy ribbontail catshark is a species of finback catshark, familyProscylliidae, distributed patchily in the western Indo-Pacific from Tanzania to the Philippines. It occurs around the edges of continental and insular shelves at a depth of, typically on or near mud bottoms. One of the smallest living shark species, the pygmy ribbontail catshark grows to a maximum known length of. It has a slender body with a low, ribbon-like tail fin, and is dark brown in color with blackish dorsal fin markings and tail bands. This shark feeds mainly on bony fishes, followed by crustaceans and then squid. It is aplacental viviparous with females bearing litters of 1-2 relatively large pups. It is of minimal significance to fisheries, being caught as bycatch in some areas.
By far the most widely distributed member of its genus, the pygmy ribbontail catshark has been reported from Tanzania, the Gulf of Aden, the Gulf of Mannar, the Bay of Bengal, the Andaman Islands, Vietnam, and the Philippines. This bottom-dwelling shark occurs at depths of on outer continental and insular shelves or upper slopes, commonly over mud.
Description
The pygmy ribbontail catshark has a thin body with a short, rounded snout and elongated, oval eyes bearing rudimentary nictitating membranes. Each nostril is preceded by a short, triangular flap of skin. The mouth is wide and V-shaped, without furrows at the corners and containing numerous rows of small, multi-pointed teeth that become more comb-like towards the sides. There are papillae on the roof of the mouth and the edges of the gill arches. The two dorsal fins are of comparable size, the first positioned slightly closer to the pectoral than the pelvic fins and the second over the anal fin. The caudal fin is low and long, comprising a quarter of the total length or more, and lacks a lower lobe. The coloration is a plain dark brown, with black markings on the dorsal fins and darker bands on the caudal fin. The maximum recorded lengths are for a male and for a female. One male shark long weighed, and a pregnant female long weighed.
Biology and ecology
The pygmy ribbontail catshark is reportedly very abundant in some places, such as off southern India and the Philippines. One study in Indian waters found that 55% of this shark's diet was composed of bony fishes, 28% of crustaceans, 14% of squid, and the remainder of other items including a bivalve. Reproduction is aplacental viviparous, with the developing young being sustained by a yolk sac until they are ready to be born. Female pygmy ribbontail catsharks are capable of becoming pregnant at long, though only females over long have been found with fully developed fetuses, suggesting that they grow substantially during the gestation period. One or two pups are born at a time; the newborns are extremely large relative to their mothers, measuring around in length. Males reach sexual maturity at a length of and females at perhaps. This is comparable to the sizes at maturity of the spined pygmy shark and the dwarf lanternshark, ranking the pygmy ribbontail catshark among the world's smallest sharks. Due to the difficulties involved in assessing reproductive maturity in sharks, whether one of these species is truly smaller than the others cannot yet be definitively determined.
