Ventral Surface Of Head Research Articles

Integrative taxonomy reveals a new species of Characidium (Characiformes: Crenuchidae) shared by tributaries of upper Tapajós and Xingu river basins, Brazil

AbstractA new species of Characidium shared by adjacent tributaries of the upper portions of the Tapajós and Xingu river basins is described. Characidium varii, new species, can be distinguished from the congeners by having distinctly speckled pattern of colouration, including dark blotches on cheek and ventral surface of head, by having conspicuous dark marks on fins, along with a single row of dentary teeth, isthmus completely covered by scales, 14 circumpeduncular scales, and swimbladder reduced. Molecular data reinforce the validation of the new species. The distribution of C. varii supports the hypothesis of the existence of a faunistic mixing between Tapajós and Xingu river basins, corresponding to the region of the Serra do Cachimbo and surrounding areas, previously proposed in the literature.

A new species of Bregmaceros (Gadiformes: Bregmacerotidae) from the eastern Pacific Ocean, with comments on B. atlanticus and B. japonicus.

A new species of Bregmaceros is described based on a series of specimens from the eastern Pacific Ocean from near the Hawaiian Islands eastward to the California Current region. The new species bears considerable similarity in body shape and pigmentation to other overall darkly pigmented species with moderately high anal-fin counts (5159 in B. moseri) and modified prehaemal anal-fin pterygiophores (B. atlanticus and B. japonicus). The form and occurrence of these modified pterygiophores among Bregmaceros species is discussed. The new species is distinguished from B. atlanticus and B. japonicus and other undescribed forms in the historical literature commonly referred to Bregmaceros mcclellandi based on its high precaudal (prehaemal) vertebral counts (15 or 16 vs. 1315, typically 14) and associated elongation of the anterior portion of the body, and dark pigmentation concentrated dorsally on body and on head dorsal to nares anteriorly and operculum posteriorly but little or no pigment on lateral and ventral surfaces of head. The new species uniquely shares with these other species the modified prehaemal anal-fin pterygiophores and a lack of posterior bifurcation of the coelomic space otherwise present in the remaining species in the genus.

A new species of the conger eel genus Macrocephenchelys from deep waters of the Arabian Sea.

A new species of the genus Macrocephenchelys is described herein based on a single specimen collected from the deep-sea trawl landing at Kalamukku fish landing centre, Kerala coast, Arabian Sea. The new species is distinguished by having a dorsal-fin origin behind the middle of pectoral fin, a larger head, shorter trunk, larger gill opening, dorsal surface of body with dark-brown colour and ventral surface of head and belly with numerous patches of melanophores before anus, vertebrae 14-30-151. The new species shares most of the characteristics with Macrocephenchelys brevirostris but differs from it by having a more anterior dorsal-fin origin (vs. over the tip or slightly behind the pectoral-fin tip), larger head [15.3% total length (TL) vs. 10.5%-13.9% TL, 53.2% pre-anal length (PAL) vs. 35.8%-47.6% PAL], shorter trunk length (13.6% TL vs. 14.4%-20.6% TL, 47.3% PAL vs. 52.4%-66.2% PAL); further it shows 7.9%-8.1% genetic divergence from the sequences of M. brevirostris.

Bregmaceros anchovia sp. nov., a new codlet species from the western Pacific Ocean (Gadiformes: Bregmacerotidae).

A new codlet species is described from Japan, Taiwan, Indonesia and Australia. It is distinguished from its congeners by having a pointed snout extending beyond jaws, a stripe of black dots above anal-fin base, a black vertical band on caudal-fin base, and the following combination of characters: ventral surface of head and abdomen devoid of melanophores; ventral portion of abdominal vertebrae with a pointed parapophysis and a blunt ventral post-zygapophysis; peritoneum, pyloric caeca, and intestine pale; dorsal-fin rays 46-52; anal-fin rays 47-55; pectoral-fin rays 15-17; principal caudal-fin rays 12‒14; caudal vertebrae 35‒39; total vertebrae 50-54. Furthermore, as a result of this study, Bregmaceros pescadorus Shen described from southwestern Taiwan is herein recognized as a junior synonym of Bregmaceros nectabanus Whitley.

Taxonomic review of the typical long-snouted species of Corydoras (Siluriformes: Callichthyidae) from the río de La Plata basin

Abstract The typical long-snouted species of Corydoras from the río de La Plata basin were reviewed herein, and the previously proposed synonymy of Corydoras ellisae was corroborated. Corydoras areio and C. aurofrenatus are diagnosed from their congeners, excluding those in lineage 1, by the following features: temporal sensory canal in sphenotic with two pores; upper tooth plate of branchial arch with three or four series of teeth; fleshy flap at mouth corner. Corydoras areio differs from all lineage 1 congeners by having infraorbital 2 with relatively wider posterior laminar expansion; absence of large patches of black pigmentation on the body and absence of conspicuous concentration of dark brown or black chromatophores on anterior portion of the dorsal fin; and presence of blotches on flanks not aligned in longitudinal series. Corydoras aurofrenatus differs from all lineage 1 congeners by having ventral surface of head and trunk densely covered by small, not coalescent platelets; middle portion of flank with two or three dark brown or black patches (below the dorsal-fin, below the adipose-fin base, and on the caudal peduncle base, diffuse and variably present), patches decreasing in size posteriorly; poorly developed fleshy flap at the corner of mouth; anteroventral portion of cleithrum exposed.

A new species of Hoplomyzon (Siluriformes: Aspredinidae) from Maracaibo Basin, Venezuela: osteological description using high-resolution computed microtomography of a miniature species

ABSTRACT A new miniature species of banjo catfish of the genus Hoplomyzon is described from the Lake Maracaibo Basin in Venezuela. The new species is distinguished from all its congeners by the straight anterior margin of the mesethmoid (vs. a medial notch); a smooth and straight ventral surface of the premaxilla (vs. presence of bony knobs on the ventral surface of premaxilla); absence of teeth on dentary (vs. teeth present on dentary); configuration of ventral vertebral processes anterior to anal fin, which are composed of single processes anterior to anal-fin pterygiophore (vs. paired process); presence of several filamentous barbel-like structures on the ventral surface of head of adults (vs. small papillous structures in the ventral surface of head of adults); and 8 anal-fin rays (vs. 6 or 7). An extensive osteological description is made of the holotype using high-resolution x-ray computed microtomography (HRXCT).

A new species of the armored catfish Parotocinclus (Loricariidae: Hypoptopomatinae), from the Amazon basin in Colombia

A new species of hypoptopomatine cascudinho is described from a creek tributary to the Amazon River in Leticia, Amazonas Departament, Colombia. The new species of Parotocinclus is distinguished from congeners from northeastern to southeastern Brazilian rivers in having the cheek canal plate elongated posteriorly on the ventral surface of head and contacting the cleithrum. It is diagnosed from P. collinsae (Essequibo River basin, Guiana) and P. halbothi (rio Trombetas basin, Brazil and Marowijne River, Suriname), by having a triangular patch of dark pigmentation on the anterior portion of the dorsal-fin membrane, by the absence of unicuspid accessory teeth on both the premaxilla and dentary, and by having a Y-shaped light mark on the snout. The new species of Parotocinclus is distinguished from all remaining congeners by having a pigmentation pattern consisting of conspicuous dark dots smaller than a pupil diameter, broadly distributed dorsally and ventrally.

A New Species ofArapaima(Osteoglossomorpha: Osteoglossidae) from the Solimões River, Amazonas State, Brazil

A new species of Arapaima has been discovered from the central Amazon of Brazil. This new taxon is readily distinguished from all other Arapaima by the following three characters: 1) dorsalmost lateralis sensory cavity on preopercle extremely slender (vs. broadly oval or nearly rectangular in other nominal taxa); 2) ventrolateral margin of head where third infraorbital meets anterior limb of preopercle strongly angled such that ventral surface of head is almost flat (vs. ventrolateral margin of head relatively rounded); and 3) anterior third of dorsal-fin base covered with an enlarged, thickened sheath that hides anterior dorsal-fin rays when adpressed (vs. no thickened sheath on anterior base of dorsal fin and anterior dorsal-fin rays visible when adpressed). Distinguished from all other Arapaima except A. agassizii by having extremely long fourth infraorbital. Distinguished from A. arapaima and all other examined non-type specimens by notably slender body (the holotypes of A. gigas, A. mapae, and A. agassizii also have slender bodies). Further distinguished from A. mapae and A. agassizii by having relatively deep caudal peduncle (6.0% SL, vs. ∼4.0% in latter two taxa), and from A. gigas by having dentary teeth in a single row (vs. dentary teeth in 2–2.5 irregular rows). This species was collected near the confluence of the Solimões and Purus rivers in Amazonas State, Brazil. It is the first new species of Arapaima to be described since 1847, and comparisons with Arapaima from Mamirauá Reserve demonstrate that there are at least two species of Arapaima present in Amazonas State.

A new dark-dotted species of Hypostomus Lacépède (Siluriformes: Loricariidae) from rio Paraguaçu, Bahia State, Brazil

A new species of Hypostomus Lacépède is described from the rio Paraguaçu basin, Bahia State, Brazil. The new species is distinguished from its congeners by having black and conspicuous dots on a pale background, which are similar in size on the head, trunk, and fins, along with ventral surface of head and abdomen naked or the latter plated exclusively on its anterior portion, absence of ridges on head and trunk, and caudal-fin lobes relatively similar in length. The new species further differs from the sympatric H. chrysostiktos by having seven branched dorsal-fin rays instead of 10-11 and represents the eleventh siluriform species endemic to the rio Paraguaçu basin.

Trigonognathus kabeyai, a new genus and species of the squalid sharks from Japan

Two specimens of the peculiar squalid shark,Trigonognathus kabeyai gen. et sp. nov., were collected from the coastal waters of Wakayama and Tokushima, Japan, by bottom trawl at depths of 330 and 360 meters. Shape of teeth similar in both jaws; slender, unicuspid, canine-like, without any cusplets or serrations, with weak thin fold on both lingual and labial sides in anterior teeth on both jaws; tooth at symphysis of each jaw longest. Interspace between teeth very wide. Both jaws triangular in shape. Most of dermal denticles on body and head roughly rhombic, swollen very much near central part, with about 10–40 facets on the dorsal surface of its crown. Preoral snout length very short. Many small organs considered to be photophores present mainly on ventral surfaces of head and body.

A New Cyclopoid Copepod (Chondracanthidae) Parasitic on the Armored Sea Robin from the Florida Straits

Rhynchochondria longa gen. et sp. n. was found parasitic on the wall of the branchial chamber of the armored sea robin, Peristedion platycephalum (Goode and Bean), taken from the Florida Straits at a depth of 366 to 450 m. The new copepod differs from the known genera in the family Chondracanthidae in the female having a large, snoutlike rostrum and a trilobed swelling with a long middle process on the sternal area behind leg 1, and in both male and female having three pairs of biramous legs. The copepod is remarkable in having more than one dwarf male attached to the female. In the winter of 1965, while the author was making a general collection of parasitic copepods of marine fishes on board the R/V Oregon during Cruise 105, 12 female copepods were recovered from the branchial cavities of 12 armored sea robins, Peristedion platycephalum (Goode and Bean), caught with a 60-ft trawl net in the Florida Straits. Subsequent study of these copepods revealed that they represent a new genus and species of the family Chondlracanthidae. Two females and three males were dissected and examined in lactic acid, and the figures were drawn with the aid of a camera lucida. All measurements are in millimeters unless otherwise indicated. Genus Rhynchochondria gen. n. Female: Cephalosome fused with first pedigerous segment and separated from rest of body by a distinct neck. Rostrum snoutlike; another long process located immediately behind leg 1 on ventral surface of head. Second, third, and fourth pedigerous segments fused into a square trunk, bearing small, fused genital segment and abdomen at posterior end. Caudal ramus present. First antenna indistinctly 6-segmented; second antenna uncinate, with accessory antennule. Mandible falcate and denticulated; paragnath present; first maxilla a knob bearing four elements; second maxilla 2-segmented, terminal segment armed with strong teeth. Maxilliped 3-segmented, terminal segment unguiform. Legs 1 to 3 biramous, remi 2-segmented. Leg 4 absent. Legs 5 and 6 present. Male: Dwarf, attached to female by means of second antennae. Metamerism of body distinct, with single postgenital segment. Caudal ramus and cephalic appendages as in female. First three pairs of legs biramous, rami 2-segmented, except Received for publication 3 August 1966. * This study was done in partial fulfillment of the requirements for the degree of Doctor of Philosophy at Boston University. 406 third endopod, where it is 1-segmented. Leg 4 absent. Legs 5 and 6 present. Type-species: Rhynchochondria longa sp. n. (Rhynchos = snout, chondria cartilage; longa -= long, alluding to the long sternal process and terminal seta on caudal ramus). Gender: Feminine. Rhynchochondria longa sp. n.