Heteralosia slocomi King, 1938
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publication ID |
https://doi.org/ 10.4202/app.2010.0096 |
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persistent identifier |
https://treatment.plazi.org/id/5A528799-FFEE-8408-F100-6013D729FAC4 |
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treatment provided by |
Felipe |
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scientific name |
Heteralosia slocomi King, 1938 |
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Heteralosia slocomi King, 1938 View in CoL
Fig. 1 View Fig .
Material examined.— Fifty−two specimens, twenty−three disarticulated ventral valves, and eleven disarticulated dorsal valves. Registered material: Six complete specimens ( UCMP 155651 View Materials ; 155653; 155657; 155658; 155660; 155661), two disarticulated ventral valves ( UCMP 155654 View Materials ) , and three disarticulated dorsal valves ( UCMP 155662 View Materials ) .
Diagnosis.—Small; subcircular; gently concavo−convex shells; spines bidirectional; both valves lamellose; socket ridges extending to border adductor scars posteriorly, prominent median septum supports cardinal process.
Description.—Small shells up to 15 mm in length, 16 mm in width and 6 mm in thickness. Shell outline subcircular, with more rounded antero−lateral margins than posterolateral margins; gently concavo–convex with greatest width just anterior of the mid–length; planoconvex in lateral profile. Shell surface lamellose in both valves and spines developed only on ventral valve. Ventral valve slightly transverse and convex; umbo low and broad with no observed cicatrix; surface of ventral disk lamellose, with spines usually oriented parallel to the surface, but some can be oriented perpendicularly; spines are hollow, usually around 3 mm in length, and a row of curved and short spines may be present in the cardinal area of some specimens; short cardinal area, occupying one–third of the hinge length; narrow triangular delthyrium. Dorsal valve moderately concave; lamellose but lacking spines. Ventral interior with large, conical teeth. Dorsal interior with a narrow cardinal ridge with a gently bilobate cardinal process; prominent median septum reaching half valve length extending from the cardinal process; deep, conical dental sockets with socket ridges extending to border of adductor muscle scars posteriorly; subrounded and slightly raised adductor scars; endospines may be present on antero–lateral margins and around the septum.
Remarks.—Specimens contain all the diagnostic characters of the type−species of the genus. This is the only Pennsylvanian species that is assigned certainly to the genus and therefore, there is no necessity of further comparison. However, the species Strophalosia spondyliformis White and St. John, 1867 is placed with doubts in synonymy because it resembles Heteralosia slocomi , but S. spondyliformis has been previously assigned to the genera Aulosteges , Strophalosia , and Leptalosia (see Carter and Carter 1970). Further comparison of Heteralosia with allied genera, such as Strophalosia and Etherilosia , can be found in previous studies ( Archbold 1993; Brunton et al. 2000; Angiolini 2007).
Geographic and stratigraphic range.—Pennsylvanian, USA.
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