Amelangia ornata, Štamberg & Werneburg, 2023

Štamberg, Stanislav & Werneburg, Ralf, 2023, New Genus And Species Of The Family Aeduellidae (Actinopterygii) From The Lower Goldlauter Formation (Asselian, Lower Permian) Of The Thuringian Forest (Germany), Fossil Imprint 79 (2), pp. 144-151 : 146-149

Amelangia ornata sp. nov.

Text-figs 2 , 3

H o l o t y p e. Specimen NHMS-Am4219 (part and counterpart) deposited in Naturhistorisches Museum Schloss Bertholdsburg Schleusingen; Germany.

E t y m o l o g y. Ornãtus – derived from the sculpture decorating the surface of the operculum, suboperculum and branchiostegal ray.

M a t e r i a l. Only the type specimen is known.

D i a g n o s i s. Aeduellid fish with a total length of about 12 cm. Orbit surrounded posteriorly by three small infraorbitals, dorsally by a large dermosphenotic, anteriorly by a sickle-shaped supraorbital anterior with distinct ridges. Many small suborbital bones and narrow dermohyal present anterior to operculum. Maxilla with low maxillary plate is triangular. Depth of maxillary plate 3.1 times total length of maxilla. Only one branchiostegal ray present. A distinct sculpture consisting of tuberculations covers surface of operculum, suboperculum, and partially the branchiostegal ray. Pectoral fin sits on small lobe covered with scales. Base of dorsal fin sits on field of small scales. Segments of lepidotrichia of dorsal fin have sigmoidal sutures between them. Scale count:

28

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10 - -

T y p e l o c a l i t y. Gehlberg, sports area, Thuringian

Forest, Germany.

T y p e h o r i z o n. Lower Goldlauter Formation,

Asselian, Thuringian Forest Basin.

D e s c r i p t i o n. Positive and negative impressions of the individual show the skull and the anterior part of the trunk, including the pectoral, ventral and dorsal fins ( Text-fig. 2a, b ). It can be assumed, by comparing with the proportions of the body of Aeduella blainvillei , that the individual reached a total length of about 12 cm. The maximum depth of the body (25 mm) is reached in the area between the pectoral and pelvic fins.

Skull roof. The bones of skull roof are not completely preserved ( Text-fig. 3a, b ). The right frontal, which is broad and short, is partially preserved. The specimen shows fine remains of numerous tuberculations, suggesting that the surface of the frontal was originally decorated with very numerous distinct tubercles, and anteriorly with short ridges oriented parallel to the anterior margin. A short section of the supraorbital canal is located in the anterior part of the bone, near its lateral margin. The right parietal on the specimen is longer than it is wide, and no sculpture or remnants of sensory canals are preserved on the parietal. The large dermosphenotic lining the lateral margin of the frontal is the best-preserved bone of the skull roof. It extends posteriorly to the level of the frontal contact with the parietal, and abuts the dermopterotic posteriorly. The lateral margin is slightly concave, and flanks the orbit dorsally. The dermosphenotic forms a lateral process in its posterior part, then gradually narrows anteriorly, where it contacts the supraorbital anterior. On the dorsal surface of the bone, several ridges parallel to the lateral margin of the bone are preserved. Posterior to the dermosphenotic is a somewhat preserved rectangular dermopterotic, which flanks the parietal laterally. Neither the sculpture nor the sensory canals are preserved. The bones posterior to the parietal and dermopterotic are completely indistinct, except for a small rectangular bone that is probably part of a band of extrascapular bones. A fragment of the bone anteriorly to the frontal Štamberg interprets to be nasal.

The circumorbital series ( Text-fig. 3a, b ) consists of, in addition to the dorsally situated dermosphenotic, the supraorbital anterior and antorbital anteriorly, jugal ventrally, and three smaller infraorbital bones posterior to the orbit. The supraorbital anterior is a slightly sickle-shaped bone, with the posterior margin ringing the orbit. The supraorbital anterior bears distinct ridges arranged concentrically parallel to the margins of the bone. The holotype preserves the supraorbital anterior of both the right and left sides ( Text-fig. 3a, b ). The antorbital is preserved anterior to the supraorbital anterior. A fragment of an anteroposteriorly elongated narrow jugal lines the dorsal margin of the suborbital portion of the maxilla ventral to the orbit. The posterior margin of the orbit is flanked by three small infraorbitals in the space between the posterior end of the jugal and the lateroventral margin of the dermosphenotic process. Across the orbit is an impression of a skeletal fragment appearing as a band of five small bones laid in a single line. It can be assumed that these are fragments of circumorbital bones from the left side of the skull ( Text-fig. 3a, b ). The articulation of this skeletal fragment is probably due to the course of the infraorbital canal and the short outlying canals. A similar structure on the bones can be observed in Aeduella blainvillei illustrated by Heyler (1969: pl. 21, fig. 2).

Cheek. The area between the orbit and opercular bones is filled with numerous small suborbital bones ( Text-fig. 3a, b ). Nine small oval-shaped bones can be found on the specimen. Between the suborbital bones and the operculum is a fragment of a dorsoventrally extended dermohyal. Several suborbital bones from the left side of the skull are displaced anteriorly to the skull roof bones. The position and shape of the preoperculum is very indistinct. The maxilla is typically aeduellid, narrow anteriorly and progressively deeper posteriorly. The posterior portion of the maxilla is relatively low, and its depth is 3.1 times the total length of the maxilla. The anterior part of the maxilla has numerous well-developed tubular teeth, consisting of a tube and a small pointed tooth at the end of the tube. The same teeth are preserved on the mandible. The teeth on the upper and lower jaw are of the same size and closely spaced.

Opercular apparatus. The operculum, suboperculum, branchiostegal ray, and lateral and median gulars form the dermal bones of the opercular apparatus ( Text-fig. 3a, b ). The operculum is rounded in its dorsal part, markedly extended dorsoventrally, whereas the dorsal part of the operculum is angular and inclined anteriorly. There is an imperfectly preserved border between the operculum and suboperculum. Both bones bear numerous tuberculations, with their spike-like apices directed posteriorly and covering the entire surface of the operculum and suboperculum. One branchiostegal ray lies between the suboperculum and the lateral gular. The small tuberculations on the branchiostegal ray have the same shape as on the suboperculum and operculum. The lateral gular anterior to the branchiostegal ray is almost twice the area of the branchiostegal ray. The lateral half of the outer surface of the bone bears numerous long and short ridges parallel to the lateral margin of the bone. The medial margin of the lateral gular forms a fold where the convex part of the lateral margin of the median gular fits. The median gular is approximately rhombic in shape, antero-posteriorly elongated and much narrower than the lateral gular. In the medial part of the bone, the impression of the pit line of the gular is visible.

Shoulder girdle. Only a narrow fragment of the supracleithrum is visible posterior to the operculum. An arcuate cleithrum lining the suboperculum extending to the operculum is evident posterior to the opercular bones.

Fins. The pectoral fin sits on a small lobe covered with minute scales ( Text-fig. 2b, c ). The anterior margin of the fin is turned dorsally. The lepidotrichia are articulated, and the anterior margin of the fin is protected by the terminal pointed segments of the lepidotrichia. The pelvic fin is small, sitting on four vertical scale rows, and its base begins behind the tenth scale row. The number of lepidotrichia is indeterminate. The dorsal fin is very well preserved. Its base begins behind the 28 th scale row and extends over the six scale rows. There is a very distinct field of small scales along the base of the dorsal fin ( Text-fig. 3d ). The fin is composed of 25 lepidotrichia, which are articulated and divide dichotomously distally. The distal parts of the lepidotrichia are separated from each other. The sutures between the segments of lepidotrichia are sigmoidal.

Squamation. The scales on the side of the body are rectangular, and the largest scales are those in the anterior part of the body, on the flank, in rows along the lateral sensory line ( Text-fig. 3e ). Their size decreases posteriorly. The posterior margin of the scales is serrated. The serrated margin is particularly well developed in the scales on the anterior portion of the fish, and the number of serrations on the posterior margin of the scale decreases towards the posterior portion of the fish. The outer margin of the scales is not sculptured, except for incremental lines parallel to the posterior margin of the scales. Scales bearing the lateral sensory canal are preserved on the entire preserved body fragment. There are 8 scales in a vertical row anterior to the dorsal fin, dorsally to the lateral sensory line. Four large dorsal scutes are developed in front of the dorsal fin.

Figures

Text-fig. 2. Amelangia ornata gen. et sp. nov. Part (a) and counterpart (b) of the holotype NHMS-Am4219. Gehlberg (Thuringian Forest, Germany; Lower Goldlauter Formation, Asselian). Scale bars 10mm.

Text-fig. 3. a–e: Amelangia ornata gen. et sp. nov., Holotype NHMS-Am4219 from Gehlberg (Thuringian Forest, Lower Goldlauter Formation, Asselian), scale bars 5mm. a, b: Photograph and drawing of skull. c: Lobe of pectoral fin. d: Dorsal fin with field of minute scales along base of fin. e: Scales in anterior part of body including scales of lateral sensory line. f–g: Aeduellid fish cf. Amelangia ornata, from Tatobity (Krkonoše Piedmont Basin, Chotěvice Formation, Asselian), scale bars 5mm. f: Left operculum in lateral view, MHK-G 67. g: Right suboperculum in lateral view with numerous tubercles, mainly in ventral half of bone, MHK-G 66. Abbreviations: Ant – antorbital, Cl – cleithrum, Dent – dentary, Dhy – dermohyal, Dpt – dermopterotic, Dsp – dermosphenotic, Ext – extrascapular, Fr – fragments of the right frontal, Gu.l – lateral gular, Gu.m – median gular, Io.p – infraorbitals posteriorly from orbit, Io? –probably fragments of infraorbitals, Ju – jugal, Mx – maxilla, Na – nasal, Op – operculum, Pa – parietal, Rbr – branchiostegal ray, Sbo – suborbital, Scl – supracleithrum, Sop – suboperculum, Sup.l – supraorbital anterior – left, Sup.r – supraorbital anterior – right.