Southern sawtail catshark
Encyclopedia
The southern sawtail catshark (Galeus mincaronei) is a species
of catshark
, family
Scyliorhinidae, endemic to southern Brazil
. It inhabits deepwater reefs on the upper continental slope at a depth of 236–600 m (774.3–1,968.5 ft). Reaching at least 43 cm (16.9 in) in length, this slim-bodied species closely resembles the Antilles catshark
(G. antillensis). It has a prominent crest of enlarged dermal denticles along the dorsal edge of the caudal fin, as well as a distinctive color pattern of dark oval blotches, outlined in white, along its back. The southern sawtail catshark is oviparous, with females producing reddish egg capsules. The International Union for Conservation of Nature (IUCN) has assessed it as Vulnerable
; it is often taken as bycatch
and may be threatened by intensifying squid
fishing.
s set off Rio Grande do Sul
, Brazil, in 1988. Initially identified as Galeus antillensis, the species was described in a 2001 issue of the scientific journal
Mare Magnum by Jules Soto, who named it after Michael Maia Mincarone for his contributions to the Museu Oceanográfico do Vale do Itajaí. The type specimen is an adult male 40 cm (15.7 in) long.
The southern sawtail catshark closely resembles G. antillensis, and with it belongs to the G. arae species complex
along with G. arae, G. cadenati, and G. springeri. In 2006, Getulio Rincon and Carolus Vooren reported that the range of morphometric variation in this species was greater than previously thought, casting doubt on the characters originally used to distinguish it from G. antillensis, such as the length of the pectoral fin margins. They recommended further study to resolve the status of the two species.
, and may occur as far north as São Paulo
. Its total range is estimated to encompass less than 20000 sqkm of area. This species has been recorded from between the depths of 236 and 600 m (774.3 and 1,968.5 ft), but is most common below 400 m (1,312.3 ft). Demersal in nature, it favors deepwater reefs on the upper continental shelf
, that are rich in sea fans, hard corals, sponges, crinoid
s, and brittle star
s.
s (protective third eyelids); they are followed by tiny spiracle
s. The ridge beneath each eye is indistinct. The anterior rims of the nostrils are enlarged into triangular skin flaps. The large mouth forms a short, wide arch, with fairly long, deep furrows around the corners; males have a slightly longer, narrower mouth and larger teeth than females. There are around 57–71 upper tooth rows and 56–63 lower tooth rows. Each tooth has a narrow central cusp flanked by one or two smaller cusplets on either side. There are five pairs of gill slit
s, with the fourth and fifth over the pectoral fin bases.
The first dorsal fin
originates over the rear of the pelvic fins, while the second dorsal fin originates over the rear of the anal fin. Both dorsal fins are small with rounded apexes; the first is slightly smaller than the second. The pectoral fins are fairly large, with rounded corners. The pelvic fins are small and relatively broad; adult males have rather short, thick claspers that bear hooks on their inner surfaces. The anal fin base measures between 11 and 14% of the total length, exceeding the distance between the pelvic and anal fins and ranging from longer to shorter than the distance between the dorsal fins. The caudal fin is short, with a small lower lobe and a ventral notch near the tip of the upper lobe. The body is covered by small, overlapping dermal denticles, each has a crown bearing a horizontal ridge and three teeth on the posterior margin. A saw-like crest of enlarged denticles is present along the anterior half of the caudal fin dorsal edge. The dorsal coloration is reddish brown with a series of large oval blotches along either side of the back. The blotches are darker and outlined in white, and become less distinct towards the tail. The fins are dark, with or without lighter margins, and the underside is off-white. The inside of the mouth is blackish.
with the abundant freckled catshark
(Scyliorhinus haeckelii). Reproduction is oviparous. Adult females have a single functional ovary
, on the right, and two functional oviduct
s; a single egg matures within an oviduct at a time. The egg is enclosed in a reddish vase-shaped capsule, measuring roughly 5–6 cm (2–2.4 in) long and 4 cm (1.6 in) wide. with coiled tendrils at the four corners. Males and females reach sexual maturity
at 36–38 cm (14.2–15 in) and 35–39 cm (13.8–15.4 in) long respectively.
on bottom longlines and in bottom trawls and traps, deployed by goosefish
and squid
fisheries. Given its very limited range, its population may be threatened by increasing levels of squid fishing activity. The International Union for Conservation of Nature (IUCN) has therefore assessed this species as Vulnerable
.
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
of catshark
Catshark
Catsharks are ground sharks of the family Scyliorhinidae, with over 150 known species. While they are generally known as catsharks, many species are commonly called dogfish....
, family
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...
Scyliorhinidae, endemic to southern Brazil
Brazil
Brazil , officially the Federative Republic of Brazil , is the largest country in South America. It is the world's fifth largest country, both by geographical area and by population with over 192 million people...
. It inhabits deepwater reefs on the upper continental slope at a depth of 236–600 m (774.3–1,968.5 ft). Reaching at least 43 cm (16.9 in) in length, this slim-bodied species closely resembles the Antilles catshark
Antilles catshark
The Antilles catshark is a common but little-known species of catshark, family Scyliorhinidae. It is found on or near the bottom at a depth of off Florida and the West Indies from Jamaica to Martinique. It was once regarded as a subspecies of the similar roughtail catshark , along with the...
(G. antillensis). It has a prominent crest of enlarged dermal denticles along the dorsal edge of the caudal fin, as well as a distinctive color pattern of dark oval blotches, outlined in white, along its back. The southern sawtail catshark is oviparous, with females producing reddish egg capsules. The International Union for Conservation of Nature (IUCN) has assessed it as Vulnerable
Vulnerable species
On 30 January 2010, the IUCN Red List of Threatened Species identified 9694 Vulnerable species, subspecies and varieties, stocks and sub-populations.-References:...
; it is often taken as bycatch
Bycatch
The term “bycatch” is usually used for fish caught unintentionally in a fishery while intending to catch other fish. It may however also indicate untargeted catch in other forms of animal harvesting or collecting...
and may be threatened by intensifying squid
Squid
Squid are cephalopods of the order Teuthida, which comprises around 300 species. Like all other cephalopods, squid have a distinct head, bilateral symmetry, a mantle, and arms. Squid, like cuttlefish, have eight arms arranged in pairs and two, usually longer, tentacles...
fishing.
Taxonomy
The first known specimens of the southern sawtail catshark were caught in a series of experimental fish trapFish trap
A fish trap is a trap used for fishing. Fish traps may have the form of a fishing weir or a lobster trap. A typical trap might consist of a frame of thick steel wire in the shape of a heart, with chicken wire stretched around it. The mesh wraps around the frame and then tapers into the inside of...
s set off Rio Grande do Sul
Rio Grande do Sul
Rio Grande do Sul is the southernmost state in Brazil, and the state with the fifth highest Human Development Index in the country. In this state is located the southernmost city in the country, Chuí, on the border with Uruguay. In the region of Bento Gonçalves and Caxias do Sul, the largest wine...
, Brazil, in 1988. Initially identified as Galeus antillensis, the species was described in a 2001 issue of the scientific journal
Scientific journal
In academic publishing, a scientific journal is a periodical publication intended to further the progress of science, usually by reporting new research. There are thousands of scientific journals in publication, and many more have been published at various points in the past...
Mare Magnum by Jules Soto, who named it after Michael Maia Mincarone for his contributions to the Museu Oceanográfico do Vale do Itajaí. The type specimen is an adult male 40 cm (15.7 in) long.
The southern sawtail catshark closely resembles G. antillensis, and with it belongs to the G. arae species complex
Species complex
A species complex is a group of closely related species, where the exact demarcation between species is often unclear or cryptic owing to their recent and usually still incomplete reproductive isolation. Ring species, superspecies and cryptic species complex are example of species complex...
along with G. arae, G. cadenati, and G. springeri. In 2006, Getulio Rincon and Carolus Vooren reported that the range of morphometric variation in this species was greater than previously thought, casting doubt on the characters originally used to distinguish it from G. antillensis, such as the length of the pectoral fin margins. They recommended further study to resolve the status of the two species.
Distribution and habitat
The only Galeus species in the southwestern Atlantic, the southern sawtail catshark is found off the southern Brazilian states of Rio Grande do Sul and Santa CatarinaSanta Catarina (state)
Santa Catarina is a state in southern Brazil with one of the highest standards of living in Latin America. Its capital is Florianópolis, which mostly lies on the Santa Catarina Island. Neighbouring states are Rio Grande do Sul to the south and Paraná to the north. It is bounded on the east by...
, and may occur as far north as São Paulo
São Paulo (state)
São Paulo is a state in Brazil. It is the major industrial and economic powerhouse of the Brazilian economy. Named after Saint Paul, São Paulo has the largest population, industrial complex, and economic production in the country. It is the richest state in Brazil...
. Its total range is estimated to encompass less than 20000 sqkm of area. This species has been recorded from between the depths of 236 and 600 m (774.3 and 1,968.5 ft), but is most common below 400 m (1,312.3 ft). Demersal in nature, it favors deepwater reefs on the upper continental shelf
Continental shelf
The continental shelf is the extended perimeter of each continent and associated coastal plain. Much of the shelf was exposed during glacial periods, but is now submerged under relatively shallow seas and gulfs, and was similarly submerged during other interglacial periods. The continental margin,...
, that are rich in sea fans, hard corals, sponges, crinoid
Crinoid
Crinoids are marine animals that make up the class Crinoidea of the echinoderms . Crinoidea comes from the Greek word krinon, "a lily", and eidos, "form". They live both in shallow water and in depths as great as 6,000 meters. Sea lilies refer to the crinoids which, in their adult form, are...
s, and brittle star
Brittle star
Brittle stars or ophiuroids are echinoderms in the class Ophiuroidea closely related to starfish. They crawl across the seafloor using their flexible arms for locomotion. The ophiuroids generally have five long slender, whip-like arms which may reach up to in length on the largest specimens...
s.
Description
The largest known specimen of the southern sawtail catshark measured 43 cm (16.9 in) long. This species has a slender body and a moderately short, flattened head with a pointed snout. The eyes are horizontally oval and have rudimentary nictitating membraneNictitating membrane
The nictitating membrane is a transparent or translucent third eyelid present in some animals that can be drawn across the eye for protection and to moisten it while maintaining visibility. Some reptiles, birds, and sharks have a full nictitating membrane; in many mammals, there is a small...
s (protective third eyelids); they are followed by tiny spiracle
Spiracle
Spiracles are openings on the surface of some animals that usually lead to respiratory systems.-Vertebrates:The spiracle is a small hole behind each eye that opens to the mouth in some fishes. In the primitive jawless fish the first gill opening immediately behind the mouth is essentially similar...
s. The ridge beneath each eye is indistinct. The anterior rims of the nostrils are enlarged into triangular skin flaps. The large mouth forms a short, wide arch, with fairly long, deep furrows around the corners; males have a slightly longer, narrower mouth and larger teeth than females. There are around 57–71 upper tooth rows and 56–63 lower tooth rows. Each tooth has a narrow central cusp flanked by one or two smaller cusplets on either side. There are five pairs of gill slit
Gill slit
Gill slits are individual openings to gills, i.e., multiple gill arches, which lack a single outer cover. Such gills are characteristic of Cartilaginous fish such as sharks, rays, sawfish, and guitarfish. Most of these have five pairs, but a few species have 6 or 7 pairs...
s, with the fourth and fifth over the pectoral fin bases.
The first dorsal fin
Dorsal fin
A dorsal fin is a fin located on the backs of various unrelated marine and freshwater vertebrates, including most fishes, marine mammals , and the ichthyosaurs...
originates over the rear of the pelvic fins, while the second dorsal fin originates over the rear of the anal fin. Both dorsal fins are small with rounded apexes; the first is slightly smaller than the second. The pectoral fins are fairly large, with rounded corners. The pelvic fins are small and relatively broad; adult males have rather short, thick claspers that bear hooks on their inner surfaces. The anal fin base measures between 11 and 14% of the total length, exceeding the distance between the pelvic and anal fins and ranging from longer to shorter than the distance between the dorsal fins. The caudal fin is short, with a small lower lobe and a ventral notch near the tip of the upper lobe. The body is covered by small, overlapping dermal denticles, each has a crown bearing a horizontal ridge and three teeth on the posterior margin. A saw-like crest of enlarged denticles is present along the anterior half of the caudal fin dorsal edge. The dorsal coloration is reddish brown with a series of large oval blotches along either side of the back. The blotches are darker and outlined in white, and become less distinct towards the tail. The fins are dark, with or without lighter margins, and the underside is off-white. The inside of the mouth is blackish.
Biology and ecology
The southern sawtail catshark shares its habitatHabitat
* Habitat , a place where a species lives and grows*Human habitat, a place where humans live, work or play** Space habitat, a space station intended as a permanent settlement...
with the abundant freckled catshark
Freckled catshark
The freckled catshark, Scyliorhinus haeckelii, is a cat shark of the family Scyliorhinidae found on the continental shelf and upper slope from the western Atlantic from western Venezuela, Suriname, Brazil, and Uruguay between latitudes 11° N and 32° S....
(Scyliorhinus haeckelii). Reproduction is oviparous. Adult females have a single functional ovary
Ovary
The ovary is an ovum-producing reproductive organ, often found in pairs as part of the vertebrate female reproductive system. Ovaries in anatomically female individuals are analogous to testes in anatomically male individuals, in that they are both gonads and endocrine glands.-Human anatomy:Ovaries...
, on the right, and two functional oviduct
Oviduct
In non-mammalian vertebrates, the passageway from the ovaries to the outside of the body is known as the oviduct. The eggs travel along the oviduct. These eggs will either be fertilized by sperm to become a zygote, or will degenerate in the body...
s; a single egg matures within an oviduct at a time. The egg is enclosed in a reddish vase-shaped capsule, measuring roughly 5–6 cm (2–2.4 in) long and 4 cm (1.6 in) wide. with coiled tendrils at the four corners. Males and females reach sexual maturity
Sexual maturity
Sexual maturity is the age or stage when an organism can reproduce. It is sometimes considered synonymous with adulthood, though the two are distinct...
at 36–38 cm (14.2–15 in) and 35–39 cm (13.8–15.4 in) long respectively.
Human interactions
Significant, though unquantified, numbers of southern sawtail catsharks are caught incidentallyBycatch
The term “bycatch” is usually used for fish caught unintentionally in a fishery while intending to catch other fish. It may however also indicate untargeted catch in other forms of animal harvesting or collecting...
on bottom longlines and in bottom trawls and traps, deployed by goosefish
Goosefish
Monkfish are a family, Lophiidae, of anglerfishes. They are found in the Arctic, Atlantic, Indian and Pacific Oceans where they live on sandy and muddy bottoms of the continental shelf and continental slope, at depths in excess of ....
and squid
Squid
Squid are cephalopods of the order Teuthida, which comprises around 300 species. Like all other cephalopods, squid have a distinct head, bilateral symmetry, a mantle, and arms. Squid, like cuttlefish, have eight arms arranged in pairs and two, usually longer, tentacles...
fisheries. Given its very limited range, its population may be threatened by increasing levels of squid fishing activity. The International Union for Conservation of Nature (IUCN) has therefore assessed this species as Vulnerable
Vulnerable species
On 30 January 2010, the IUCN Red List of Threatened Species identified 9694 Vulnerable species, subspecies and varieties, stocks and sub-populations.-References:...
.