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Brand new mesethmoid bones of your Acre Phractocephalus is a lot like you to out of ?P

From inside the progressive P. hemioliopterus the brand new related main region of the skull roof is almost entirely ornamented by the reticulating ridges and you will pits, with couple or no elongate, synchronous ridges and you can sulci ( Fig. 4a). On Acre Phractocephalus the fresh main region of the skull roof has many elongate ridges and sulci as well as reticulating ridges and you may pits.

The fresh new lateral ethmoid bone from P

2) Mesethmoid limbs most large ( Dining table 1); dorsal surface commonly ornamented; prior line barely emarginate so you can lightly circular ( Fig. 3a).

The mesethmoid bone from P. hemioliopterus is relatively slim-necked, smaller generally ornamented merely centrally and you will posteriorly, and its anterior boundary is actually emarginate otherwise shallowly concave ( Fig. 4a). nassi.

3) Horizontal ethmoid perhaps not too-much projecting anteriorly more than palatine condyle; the horizontal margin convex and eliminating orbital notch on margin from skull roof ( Fig. 3a).

hemioliopterus is also maybe not excessively projecting anteriorly across the olfactory part otherwise palatine condyle; but it’s concave laterally, and contains a proper defined orbital sulcus into margin out of skull roof ( Fig. 4a). Regarding the Acre Phractocephalus www.datingmentor.org/russia-chat-rooms the fresh lateral ethmoid plans much anteriorly more brand new olfactory part and palatine condyle; it is convex laterally, reducing the latest orbital sulcus with the margin out of skull roof.

Modern P. hemioliopterus possess an open prior cranial fontanelle in this a well known anxiety regarding epiphyseal area ( Fig. 4a), while in the Acre Phractocephalus new fontanelle and you may anxiety of your own epiphyseal region lack.

5) Supraoccipital processes that have circular lateral and you will posterolateral margins, rear margin concave medially; supraoccipital techniques enough time, during the dorsal see entirely layer altered anterior vertebrae off Weberian state-of-the-art ( Fig. 3a).

Brand new opercle P

Inside the progressive P. hemioliopterus the brand new supraoccipital procedure is quick, inside dorsal evaluate maybe not completely coating changed backbone regarding Weberian state-of-the-art; it’s angular horizontal and posterolateral margins, and its own rear margin is actually unusual so you’re able to concave medially and you will results a-deep unornamented expansion less than prior nuchal dish ( Fig. 4a). About Acre Phractocephalus the brand new supraoccipital process was enough time, entirely within the Weberian complex; its techniques keeps angular edges and straight horizontal margins, and its particular rear ented extension below prior nuchal plate.

hemioliopterus is actually incompletely covered with reticulating ridges and you may pits ( Fig. 5c). This new opercle is actually thus far not familiar on Acre Phractocephalus.

7) Cleithrum which have rough ornamentation extending together ventral edge building external bulge otherwise “shoulder” lateral so you can back articulation; bulge out-of “shoulder” terminating posteriorly, in accordance with termination off articular retailer out-of pectoral spine ( Figs. 5e-g).

The fresh new cleithrum out of P. hemioliopterus does not have rough ornamentation together ventral edge of “neck,” and lateral bulge out-of “shoulder” terminates posterior to the point regarding articular retailer regarding pectoral spine ( Figs. 5i, j). No cleithrum of your own Acre Phractocephalus has been found.

8) Pectoral lower back ornamentation reigned over of the rough subparallel ridges and sulci, and you can apparently few reticulating ridges and you will pits ( Fig. 5h).

This new pectoral lower back ornamentation of P. hemioliopterus is actually dominated because of the reticulating ridges and you can pits ( Fig. 5i). The fresh pectoral lower back of Acre Phractocephalus is but really unfamiliar.

Etymology. New Urumaco types of Phractocephalus is known as to have Dr. Pedro Nass during the identification from his contributions on the systematics and you will morphology out-of pimelodid catfishes of South usa.

Breakdown. Look for Lundberg ainsi que al. (1988) to have description out of neurocranium (MCN.USB 72-85 PB) and extra specifications. The following info is provided by the holotype and you may recently gotten specimens.

Neurocranium, dorsal aspect ( Fig. 3a). Outline style of head as much as rectangular, thickness across the horizontal ethmoids equal to thickness across the sphenotics, and these widths somewhat below limit width across pterotic wings; depth all over pterotics contains dos.twenty-five moments within the (45% of) dorsal skull length away from mesethmoid idea to rear side of supraoccipital techniques. Facial skin primarily apartment but margins rounded slightly down and dorsal midline much more arched posteriorly. The bones ornamented having rough reticulating ridges and you can circular pits and you will particular longitudinally elongate ridges and you can grooves, apart from olfactory capsules and extremities of mesethmoid cornua.

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