The brand new mesethmoid limbs of your own Acre Phractocephalus is much like you to out-of ?P

Into the progressive P. hemioliopterus the brand new relevant main area of the head roof is close to completely ornamented because of the reticulating ridges and you may pits, which have couples or no elongate, parallel ridges and sulci ( Fig. 4a). Throughout the Acre Phractocephalus the fresh central region of the skull roof has some elongate ridges and sulci and additionally reticulating ridges and you can pits.

The fresh horizontal ethmoid bones out of P

2) Mesethmoid bones most broad ( Desk step 1); dorsal epidermis widely ornamented; prior edge scarcely emarginate to carefully rounded ( Fig. 3a).

The new mesethmoid limbs away from P. hemioliopterus is fairly thin-necked, faster generally ornamented only centrally and you can posteriorly, and its own anterior edge are emarginate or shallowly concave ( Fig. 4a). nassi.

3) Horizontal ethmoid not an excessive amount of projecting anteriorly more than palatine condyle; the horizontal margin convex and you may getting rid of orbital level to the margin of head roof ( Fig. 3a).

hemioliopterus is additionally not too-much projecting anteriorly across the olfactory region otherwise palatine condyle; but it is concave laterally, features a highly defined orbital sulcus on margin out of skull rooftop ( Fig. 4a). About Acre Phractocephalus brand new lateral ethmoid plans far anteriorly more than the fresh olfactory part and you can palatine condyle; it’s convex laterally, getting rid of the new orbital sulcus towards the margin out of skull rooftop.

Modern P. hemioliopterus has actually an open prior cranial fontanelle in this a favorite anxiety regarding epiphyseal area ( Fig. 4a), whereas about Acre Phractocephalus new fontanelle and you may despair of the epiphyseal part lack.

5) Supraoccipital process that have game lateral and you will posterolateral margins, posterior margin concave medially; supraoccipital procedure enough time, into the dorsal look at totally level modified anterior backbone from Weberian advanced ( Fig. 3a).

Brand new opercle P

Within the progressive P. hemioliopterus the fresh supraoccipital processes is actually short, inside dorsal see perhaps not totally covering changed backbone out of Weberian cutting-edge; it offers angular horizontal and posterolateral margins, as well as rear margin try unusual to help you concave medially and you will influence an intense unornamented extension less than prior nuchal plate ( Fig. 4a). On the Acre Phractocephalus the latest supraoccipital techniques are enough time, entirely covering the Weberian state-of-the-art; their techniques has angular sides and you may upright horizontal margins, and its particular posterior ented expansion less than anterior nuchal plate.

hemioliopterus was incompletely covered with reticulating ridges and you will pits ( single muslim Fig. 5c). The fresh opercle is actually up to now not familiar from the Acre Phractocephalus.

7) Cleithrum having rough ornamentation extending along ventral edge creating outward fat or «shoulder» horizontal in order to back articulation; pouch away from «shoulder» terminating posteriorly, relative to termination regarding articular outlet of pectoral spine ( Figs. 5e-g).

The newest cleithrum out of P. hemioliopterus does not have rough ornamentation collectively ventral side of «shoulder,» while the lateral bulge out of «shoulder» terminates posterior to the stage out of articular retailer regarding pectoral lower back ( Figs. 5i, j). Zero cleithrum of your Acre Phractocephalus has been seen.

8) Pectoral lower back ornamentation controlled because of the rough subparallel ridges and sulci, and relatively few reticulating ridges and you will pits ( Fig. 5h).

This new pectoral back ornamentation out of P. hemioliopterus is dominated by the reticulating ridges and pits ( Fig. 5i). The newest pectoral lower back of the Acre Phractocephalus are but really not familiar.

Etymology. New Urumaco types of Phractocephalus is known as to have Dr. Pedro Nass inside the identification off their efforts towards the systematics and you can morphology out-of pimelodid catfishes off South usa.

Description. Look for Lundberg ainsi que al. (1988) to possess description of neurocranium (MCN.USB 72-85 PB) and additional proportions. Next information is provided with the newest holotype and you can recently acquired specimens.

Neurocranium, dorsal aspect ( Fig. 3a). Explanation style of skull just as much as square, width across the horizontal ethmoids comparable to depth all over sphenotics, that widths quite below maximum thickness across the pterotic wings; thickness all over pterotics contains dos.twenty five minutes into the (45% of) dorsal skull length from mesethmoid suggestion in order to rear edge of supraoccipital techniques. Surface mostly apartment but margins curved a little down and you will dorsal midline even more arched posteriorly. All skeleton ornamented with rough reticulating ridges and you may game pits and you can certain longitudinally elongate ridges and grooves, apart from olfactory pills and you can extremities off mesethmoid cornua.