Miocidaris connorsi Kier, 1965
Plate: MiCo-10
Series: Permian Group: Upper Formation: Bell Canyon
Locale: Bell Canyon County: Culbertson Stage: Guadalupian
Length: 33.0 mm Width: 25.0 mm Height: 8.5 mm
Specimen in photos: U.S.N.M. 144195 Holotype
Collector: Not Specified Interambulacral plate only.
Repository: Paleobiology Dept., NMNH, Smithsonian Institution
HOLOTYPE INFO:
Holotype: USNM 144195 (Kier, 1965).
Locality: USNM Locality 708u, Bell Canyon, Culberson County, Texas.
Stratigraphy: Bell Canyon Formation (Lamar Limestone Member).
SYSTEMATIC PALEONTOLOGY – TAXONOMY
Class: Echinoidea Leske, 1778
Subclass: Euechinoidea Bronn, 1860
Order: Cidaroida Claus, 1880
Family: Miocidaridae Durham & Melville, 1957
Genus: MIOCIDARIS Döderlein, 1887
Species: Miocidaris connorsi Kier, 1965
TYPE SPECIES: Cidaris keyserlingi Geinitz, 1848
DIAGNOSIS
Species known from a single interambulacral plate characterized by its extreme width relative to its height (width nearly 4 times height). The plate bears a large, central, perforate, and crenulate primary tubercle with a distinct scrobicular ring (Kier, 1965).
STRATIGRAPHICAL OCCURRENCE & DISTRIBUTION
Group: Delaware Mountain Group
Formations: Bell Canyon Formation (Lamar Limestone Member).
Stratigraphic Units: Permian, Guadalupian (Capitanian).
Counties: Culberson.
Abundance: Rare; known only from the holotype fragment.
DESCRIPTION
(Note: Description specific to M. connorsi is limited to the single plate found. Generic descriptions from Jackson, 1912 are included for context where noted).
TOP: Shape: Test of the genus is small, low, and subspheroidal (Jackson, 1912 for M. keyserlingi).
AMB: Amb shape: (Unknown for M. connorsi). In the genus, ambulacral plates are narrow and beveled under the interambulacral plates (Jackson, 1912).
INTERAMB: Shape: The holotype consists of a single interambulacral plate.
Dimensions: 33.0 mm wide; 8.5 mm high (Kier, 1965).
Arrangement: In the genus, interambulacra are composed of two columns of pentagonal plates, relatively few in number, often wide (Jackson, 1912).
Adradial Margin: Beveled over the ambulacrals (Jackson, 1912).
PORE PAIRS: Not preserved in holotype.
TUBERCLES: Primary Perforated: Yes.
Primary Crenulate: Yes.
Arrangement: The single plate bears one large, central primary tubercle.
Areolas: Scrobicules are circular or elliptical; in M. keyserlingi, they are large (Jackson, 1912).
Scrobicular Tubercles: Distinct scrobicular ring present.
Secondary Tubercles: Numerous secondary tubercles cover the extrascrobicular surface (Jackson, 1912; Kier, 1965).
GRANULES: Distribution: Surface covered with small granules (Jackson, 1912).
FASCIOLE: Absent in Cidaroids.
APICAL SYSTEM: Unknown.
PERIPROCT (ANUS): Unknown.
PERISTOME (MOUTH): (Unknown).
SPINES: Unknown for (M. connorsi). In M. keyserlingi, primary spines are up to 8 mm long with small spinules directed distally (Jackson, 1912).
SPECIMENS STUDIED & CONDITION: Holotype USNM 144195 (Single plate).
ETYMOLOGY
Named for the family of the collector or a colleague (not explicitly specified in snippet, but follows patronymic convention).
REMARKS & COMPARISONS
Remarks: As the specimen is incomplete, Jackson's (1912) generic description of Miocidaris notes that the test is typically moderate in size with adradial margins beveled over the ambulacra. Bather (referenced by Jackson) noted low apophyses on the basicoronal plates of M. keyserlingi, unique in the Paleozoic.
Comparisons:
Plate: MiCo-10
Series: Permian Group: Upper Formation: Bell Canyon
Locale: Bell Canyon County: Culbertson Stage: Guadalupian
Length: 33.0 mm Width: 25.0 mm Height: 8.5 mm
Specimen in photos: U.S.N.M. 144195 Holotype
Collector: Not Specified Interambulacral plate only.
Repository: Paleobiology Dept., NMNH, Smithsonian Institution
HOLOTYPE INFO:
Holotype: USNM 144195 (Kier, 1965).
Locality: USNM Locality 708u, Bell Canyon, Culberson County, Texas.
Stratigraphy: Bell Canyon Formation (Lamar Limestone Member).
SYSTEMATIC PALEONTOLOGY – TAXONOMY
Class: Echinoidea Leske, 1778
Subclass: Euechinoidea Bronn, 1860
Order: Cidaroida Claus, 1880
Family: Miocidaridae Durham & Melville, 1957
Genus: MIOCIDARIS Döderlein, 1887
Species: Miocidaris connorsi Kier, 1965
TYPE SPECIES: Cidaris keyserlingi Geinitz, 1848
DIAGNOSIS
Species known from a single interambulacral plate characterized by its extreme width relative to its height (width nearly 4 times height). The plate bears a large, central, perforate, and crenulate primary tubercle with a distinct scrobicular ring (Kier, 1965).
STRATIGRAPHICAL OCCURRENCE & DISTRIBUTION
Group: Delaware Mountain Group
Formations: Bell Canyon Formation (Lamar Limestone Member).
Stratigraphic Units: Permian, Guadalupian (Capitanian).
Counties: Culberson.
Abundance: Rare; known only from the holotype fragment.
DESCRIPTION
(Note: Description specific to M. connorsi is limited to the single plate found. Generic descriptions from Jackson, 1912 are included for context where noted).
TOP: Shape: Test of the genus is small, low, and subspheroidal (Jackson, 1912 for M. keyserlingi).
AMB: Amb shape: (Unknown for M. connorsi). In the genus, ambulacral plates are narrow and beveled under the interambulacral plates (Jackson, 1912).
INTERAMB: Shape: The holotype consists of a single interambulacral plate.
Dimensions: 33.0 mm wide; 8.5 mm high (Kier, 1965).
Arrangement: In the genus, interambulacra are composed of two columns of pentagonal plates, relatively few in number, often wide (Jackson, 1912).
Adradial Margin: Beveled over the ambulacrals (Jackson, 1912).
PORE PAIRS: Not preserved in holotype.
TUBERCLES: Primary Perforated: Yes.
Primary Crenulate: Yes.
Arrangement: The single plate bears one large, central primary tubercle.
Areolas: Scrobicules are circular or elliptical; in M. keyserlingi, they are large (Jackson, 1912).
Scrobicular Tubercles: Distinct scrobicular ring present.
Secondary Tubercles: Numerous secondary tubercles cover the extrascrobicular surface (Jackson, 1912; Kier, 1965).
GRANULES: Distribution: Surface covered with small granules (Jackson, 1912).
FASCIOLE: Absent in Cidaroids.
APICAL SYSTEM: Unknown.
PERIPROCT (ANUS): Unknown.
PERISTOME (MOUTH): (Unknown).
SPINES: Unknown for (M. connorsi). In M. keyserlingi, primary spines are up to 8 mm long with small spinules directed distally (Jackson, 1912).
SPECIMENS STUDIED & CONDITION: Holotype USNM 144195 (Single plate).
ETYMOLOGY
Named for the family of the collector or a colleague (not explicitly specified in snippet, but follows patronymic convention).
REMARKS & COMPARISONS
Remarks: As the specimen is incomplete, Jackson's (1912) generic description of Miocidaris notes that the test is typically moderate in size with adradial margins beveled over the ambulacra. Bather (referenced by Jackson) noted low apophyses on the basicoronal plates of M. keyserlingi, unique in the Paleozoic.
Comparisons:
- M. keyserlingi: M. connorsi is vastly larger. A six-plate fragment of M. keyserlingi measures only 5.3 mm in width, whereas the single plate of M. connorsi is 33.0 mm wide. The extreme width-to-height ratio of the M. connorsi plate distinguishes it from all other known species (Kier, 1965).
