Paracetopsis
Encyclopedia
Paracetopsis is a genus
of catfish
es (order
Siluriformes) of the family
Cetopsidae
. It includes three species
, P. atahualpa, P. bleekeri, and P. esmeraldas.
basin in northwestern Peru
and the adjoining upper reaches of the Zarumilla River
basin in southwestern Ecuador
. P. bleekeri is only known from the Pacific Ocean versant Guayas River
and Santa Rosa River basins of southwestern Ecuador. P. esmeraldas occurs in the Pacific Ocean versant rivers of northwestern Ecuador.
ine tooth patch with two or more rows of teeth and a medial gap between the contralateral components of the tooth patch. Like in other species of cetopsines, mature males have elongated distal filaments of the dorsal and pectoral fin rays and a convex (instead of straight) margin to the anal fin.
The body is relatively elongate; anteriorly the body is not compressed much, but becomes progressively compressed posteriorly. The lateral line
is complete and midlateral; though unbranched in P. bleekeri and P. esmeraldas, in P. atahualpa the lateral line has a few ventrally-direct branches on the caudal peduncle. The dorsal profile is straight to slightly convex; the ventral profile is convex at the abdomen and straight posteriorly. The caudal peduncle depth is approximately equal to its length. The head in profile is acutely triangular overall with a bluntly rounded snout. The eyes are placed on the sides of the head and are visible from above, but not from below. The mouth is inferior and the width is about one-half the length of the head. They have three pairs of barbels, one pair of slender maxillary barbels and two pairs of mental barbels; all three pairs of barbels are approximately the same length. The caudal fin is moderately- to deeply-forked and symmetrical with the tips of the lobes slightly rounded. The base of the anal fin is comparatively long. The pelvic fins are also usually moderately long.
P. atahualpa has shorter pelvic fins and is darker in colour than P. bleekeri. P. atahualpa has a maxillary barbel with a distinctly dark base instead of a pale base and a distinct notch behind the head that is not present in P. esmeraldas. Both P. atahualpa and P. esmeraldas have a distinct patch of pigment on the operculum
not present in P. bleekeri.
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
of catfish
Catfish
Catfishes are a diverse group of ray-finned fish. Named for their prominent barbels, which resemble a cat's whiskers, catfish range in size and behavior from the heaviest and longest, the Mekong giant catfish from Southeast Asia and the second longest, the wels catfish of Eurasia, to detritivores...
es (order
Order (biology)
In scientific classification used in biology, the order is# a taxonomic rank used in the classification of organisms. Other well-known ranks are life, domain, kingdom, phylum, class, family, genus, and species, with order fitting in between class and family...
Siluriformes) of the 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...
Cetopsidae
Cetopsidae
Cetopsidae is a small family of catfishes , commonly called the whale catfishes.-Taxonomy:This family contains five genera. It is divided into two subfamilies, Cetopsinae and Helogeneinae. Helogeneinae was previously a family-level group, but now it has been reclassified as a subfamily of Cetopsidae...
. It includes three species
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...
, P. atahualpa, P. bleekeri, and P. esmeraldas.
Distribution
Paracetopsis species are known from rivers of the Pacific Ocean versant. P. atahualpa is only known from the Pacific Ocean versant Tumbes RiverTumbes River
The Tumbes River , is a river in South America.The river's sources are located between Ecuadorian El Oro and Loja provinces. It is the border between El Oro and Loja, and afterwards the border between Loja and the Tumbes Region in Peru...
basin in northwestern Peru
Peru
Peru , officially the Republic of Peru , is a country in western South America. It is bordered on the north by Ecuador and Colombia, on the east by Brazil, on the southeast by Bolivia, on the south by Chile, and on the west by the Pacific Ocean....
and the adjoining upper reaches of the Zarumilla River
Zarumilla River
The Zarumilla River is a river in South America that marks the border between Peru and Ecuador. It is named after the Peruvian town of Zarumilla....
basin in southwestern Ecuador
Ecuador
Ecuador , officially the Republic of Ecuador is a representative democratic republic in South America, bordered by Colombia on the north, Peru on the east and south, and by the Pacific Ocean to the west. It is one of only two countries in South America, along with Chile, that do not have a border...
. P. bleekeri is only known from the Pacific Ocean versant Guayas River
Guayas River
The Guayas River is a river in western Ecuador. It gives name to the Guayas Province, and it is the most important river in South America that does not flow into the Atlantic Ocean or any of its seas. Its total length, including the Daule River, is 389 km.-Course:The Guayas River has one of...
and Santa Rosa River basins of southwestern Ecuador. P. esmeraldas occurs in the Pacific Ocean versant rivers of northwestern Ecuador.
Description
Paracetopsis species can be distinguished from species of all other genera in the Cetopsinae by the combination of the possession of a vomerVomer
The vomer is one of the unpaired facial bones of the skull. It is located in the midsagittal line, and articulates with the sphenoid, the ethmoid, the left and right palatine bones, and the left and right maxillary bones.-Biology:...
ine tooth patch with two or more rows of teeth and a medial gap between the contralateral components of the tooth patch. Like in other species of cetopsines, mature males have elongated distal filaments of the dorsal and pectoral fin rays and a convex (instead of straight) margin to the anal fin.
The body is relatively elongate; anteriorly the body is not compressed much, but becomes progressively compressed posteriorly. The lateral line
Lateral line
The lateral line is a sense organ in aquatic organisms , used to detect movement and vibration in the surrounding water. Lateral lines are usually visible as faint lines running lengthwise down each side, from the vicinity of the gill covers to the base of the tail...
is complete and midlateral; though unbranched in P. bleekeri and P. esmeraldas, in P. atahualpa the lateral line has a few ventrally-direct branches on the caudal peduncle. The dorsal profile is straight to slightly convex; the ventral profile is convex at the abdomen and straight posteriorly. The caudal peduncle depth is approximately equal to its length. The head in profile is acutely triangular overall with a bluntly rounded snout. The eyes are placed on the sides of the head and are visible from above, but not from below. The mouth is inferior and the width is about one-half the length of the head. They have three pairs of barbels, one pair of slender maxillary barbels and two pairs of mental barbels; all three pairs of barbels are approximately the same length. The caudal fin is moderately- to deeply-forked and symmetrical with the tips of the lobes slightly rounded. The base of the anal fin is comparatively long. The pelvic fins are also usually moderately long.
P. atahualpa has shorter pelvic fins and is darker in colour than P. bleekeri. P. atahualpa has a maxillary barbel with a distinctly dark base instead of a pale base and a distinct notch behind the head that is not present in P. esmeraldas. Both P. atahualpa and P. esmeraldas have a distinct patch of pigment on the operculum
Operculum (fish)
The operculum of a bony fish is the hard bony flap covering and protecting the gills. In most fish, the rear edge of the operculum roughly marks the division between the head and the body....
not present in P. bleekeri.