For the progressive P. hemioliopterus the newest associated central side of the head roof is almost completely ornamented by reticulating ridges and you may pits, which have partners or no elongate, synchronous ridges and sulci ( Fig. 4a). On the Acre Phractocephalus the central side of the head rooftop has many elongate ridges and you will sulci together with reticulating ridges and you can pits.
The fresh new horizontal ethmoid bones away from P
2) Mesethmoid limbs really wider ( Desk step one); dorsal surface generally ornamented; prior border hardly emarginate to help you lightly rounded ( Fig. 3a).
The newest mesethmoid bones away from P. hemioliopterus is relatively thin-necked, smaller generally ornamented simply centrally and you may posteriorly, and its prior line was emarginate otherwise shallowly concave ( Fig. 4a). nassi.
3) Horizontal ethmoid maybe not excess projecting anteriorly more than palatine condyle; its lateral margin convex and you will getting rid of orbital notch into margin away from skull roof ( Fig. 3a).
hemioliopterus is even not way too much projecting anteriorly across the olfactory area or palatine condyle; but it’s concave sideways, and contains a well outlined orbital sulcus on margin of skull roof ( Fig. 4a). On the Acre Phractocephalus this new horizontal ethmoid ideas much anteriorly more the brand new olfactory area and you will palatine condyle; it is convex sideways, eliminating the fresh orbital sulcus for the margin off head roof.
Progressive P. hemioliopterus keeps an unbarred anterior cranial fontanelle in this a well known depression out-of epiphyseal part ( Fig. 4a), whereas regarding the Acre Phractocephalus the fontanelle and despair of your own epiphyseal area are lacking.
5) Supraoccipital processes having round horizontal and you may posterolateral margins, rear margin concave medially; supraoccipital processes long, inside the dorsal evaluate totally coating altered anterior spinal vertebrae off Weberian advanced ( Fig. 3a).
The latest opercle P
Into the progressive P. hemioliopterus the latest supraoccipital process try brief, for the dorsal take a look at perhaps not completely covering changed backbone off Weberian complex; this has angular lateral and posterolateral margins, as well as rear margin are unusual so you’re able to concave medially and bearing an intense unornamented expansion lower than anterior nuchal dish ( Fig. 4a). Throughout the Acre Phractocephalus the brand new supraoccipital techniques is a lot of time, totally within the Weberian cutting-edge; their techniques features angular corners and you will upright horizontal margins, and its own rear ented expansion lower than anterior nuchal plate.
hemioliopterus are incompletely wrapped in reticulating ridges and you can pits ( Fig. 5c). The opercle was to date not familiar from the Acre Phractocephalus.
7) Cleithrum that have rough ornamentation stretching together ventral boundary forming external fat otherwise «shoulder» horizontal so you can spine articulation; pouch of «shoulder» terminating posteriorly, in line with termination away from articular socket regarding pectoral lower back ( Figs. 5e-g).
Brand new cleithrum away from P. hemioliopterus lacks coarse ornamentation with each other ventral side of «shoulder,» and the horizontal bulge from «shoulder» terminates rear to the point of articular outlet out-of pectoral lower back ( Figs. 5i, j). No cleithrum of your own Acre Phractocephalus has been found.
8) Pectoral spine ornamentation dominated because of the coarse subparallel ridges and you can sulci, and apparently pair reticulating ridges and you will pits ( Fig. 5h).
This new pectoral back ornamentation from P. hemioliopterus are ruled from the reticulating ridges and you may pits ( Fig. 5i). This new pectoral lower back of the Acre Phractocephalus are but really not familiar.
Etymology. The newest Urumaco species of Phractocephalus is known as for Dr. Pedro Nass for the detection from their efforts to your systematics and you can morphology regarding pimelodid catfishes away from South usa.
Breakdown. Select Lundberg et al. (1988) getting breakdown regarding neurocranium (MCN.USB 72-85 PB) and extra specifications. The second information is available with the fresh new holotype and recently gotten specimens.
Neurocranium, dorsal aspect ( Fig. 3a). Classification sorts of skull as much as square, depth round the horizontal ethmoids equivalent to width all over sphenotics, that widths a bit lower than limit depth across the pterotic wings; width round the pterotics contains dos.25 times inside the (45% of) dorsal skull duration of mesethmoid suggestion so you’re able to posterior side of supraoccipital techniques. Body mostly apartment however, margins curved a little downwards and you will dorsal midline even more arched posteriorly. Most of the bones ornamented having coarse reticulating ridges and you may game pits and particular longitudinally elongate ridges and you can grooves, with the exception of olfactory pills and you may extremities off mesethmoid cornua.