Pseudholaster texanus Thompson, 2016
Plate: PsTe-10
Series: Lower Cretaceous Group: Fredericksburg Formation: Kiamichi
Locale: Clifton Quarry County: Bosque Stage: Albian
Length: 39.8 mm Width: 41.8 mm Height: 23.7 mm
Specimen in photo: NPL 70936 Holotype
Collector: Ed Elliott
Repository: Non-vertebrate Paleo. Lab., Univ. of Texas
HOLOTYPE INFO:
Holotype: NPL 70936.
Locality: Clifton Chemical Lime Quarry, Clifton, Bosque County, Texas.
Stratigraphy: Kiamichi Formation, Fredericksburg Group.
SYSTEMATIC PALEONTOLOGY – TAXONOMY
Class: Echinoidea Leske, 1778
Subclass: Euechinoidea Bronn, 1860
Infraclass: Irregularia Latreille, 1825
Superorder: Atelostomata Zittel, 1879
Order: Holasteroida Durham & Melville, 1957
Family: Pseudholasteridae Smith & Jeffery, 2000
Genus: PSEUDHOLASTER Pomel, 1883
Species: Pseudholaster texanus Thompson, 2016
TYPE SPECIES: Holaster androaviensis Agassiz & Desor, 1847
DIAGNOSIS
A Pseudholaster characterized by a truncated parallelogram profile with a "negative slope" on the posterior face (top overhangs bottom). The posterior truncated end is widest above the apex. The test possesses a deep anterior sulcus and a marginal fasciole.
STRATIGRAPHICAL OCCURRENCE & DISTRIBUTION
Group: Fredericksburg
Formations: Kiamichi Formation.
Stratigraphic Units: Lower Cretaceous, Albian.
Counties: Bosque.
Abundance: Rare; only one specimen known.
DESCRIPTION
TOP: Length, width, height: 39.8 mm L × 41.8 mm W × 23.7 mm H. Top shape: Cordate; wider than tall. Widest point slightly above (anterior of) midpoint. Deep sulcus at unpaired ambulacrum. Top domed: Slightly domed above.
SIDE: Ambitus: Positioned 1/3 of height from the adoral surface. Side shape: Inflated; shaped like a parallelogram. Profile: Posterior end truncated with a negative slope (overhanging).
BOTTOM: Bottom shape: Very flat; slightly depressed at peristome. Deep rounded keel on bottom. Plastron: Large; protosternous plating.
AMB: Amb shape: Paired ambulacra are petaloid, wide, and open-ended. Unpaired ambulacrum is lanceolate, open-ended, and runs the entire length of the sulcus. Amb arrangement: Anterior paired ambulacra are flexuous and extend to the margin. Posterior paired ambulacra are much less flexed (more straight) and extend to the margin.
PORE PAIRS: Unpaired Amb: Small, round, and oblique. Paired Ambs: Outer pores only slightly elongated; inner pores more elongated. On all paired ambulacra, the posterior pore pairs are more widely spaced within the set.
TUBERCLES: Distribution: Very small and sparse aborally and adorally. Slightly larger near margins and along sides of anterior sulcus and apical system.
FASCIOLE: Marginal: Marginal fasciole present around the posterior of the test. No peripetalous fasciole.
APICAL SYSTEM: Location: Central. Shape: Elongated vertically. Genital pores: 4 genital pore pairs. Plating: Small madreporite.
PERIPROCT (ANUS): Shape: Oval; elongated vertically with pointed ends. Location: Situated just above the midpoint on the truncated posterior end. Visibility: Clearly visible from the rear; not visible from above.
PERISTOME (MOUTH): Shape: Horizontally oval (twice as wide as tall). Size: Small.
SPINES: Unknown.
SPECIMENS STUDIED & CONDITION: Holotype NPL 70936.
ETYMOLOGY
Named after the state of Texas.
REMARKS & COMPARISONS
Remarks: This species represents a rare occurrence of the genus in the Fredericksburg Group.
Comparisons:
Plate: PsTe-10
Series: Lower Cretaceous Group: Fredericksburg Formation: Kiamichi
Locale: Clifton Quarry County: Bosque Stage: Albian
Length: 39.8 mm Width: 41.8 mm Height: 23.7 mm
Specimen in photo: NPL 70936 Holotype
Collector: Ed Elliott
Repository: Non-vertebrate Paleo. Lab., Univ. of Texas
HOLOTYPE INFO:
Holotype: NPL 70936.
Locality: Clifton Chemical Lime Quarry, Clifton, Bosque County, Texas.
Stratigraphy: Kiamichi Formation, Fredericksburg Group.
SYSTEMATIC PALEONTOLOGY – TAXONOMY
Class: Echinoidea Leske, 1778
Subclass: Euechinoidea Bronn, 1860
Infraclass: Irregularia Latreille, 1825
Superorder: Atelostomata Zittel, 1879
Order: Holasteroida Durham & Melville, 1957
Family: Pseudholasteridae Smith & Jeffery, 2000
Genus: PSEUDHOLASTER Pomel, 1883
Species: Pseudholaster texanus Thompson, 2016
TYPE SPECIES: Holaster androaviensis Agassiz & Desor, 1847
DIAGNOSIS
A Pseudholaster characterized by a truncated parallelogram profile with a "negative slope" on the posterior face (top overhangs bottom). The posterior truncated end is widest above the apex. The test possesses a deep anterior sulcus and a marginal fasciole.
STRATIGRAPHICAL OCCURRENCE & DISTRIBUTION
Group: Fredericksburg
Formations: Kiamichi Formation.
Stratigraphic Units: Lower Cretaceous, Albian.
Counties: Bosque.
Abundance: Rare; only one specimen known.
DESCRIPTION
TOP: Length, width, height: 39.8 mm L × 41.8 mm W × 23.7 mm H. Top shape: Cordate; wider than tall. Widest point slightly above (anterior of) midpoint. Deep sulcus at unpaired ambulacrum. Top domed: Slightly domed above.
SIDE: Ambitus: Positioned 1/3 of height from the adoral surface. Side shape: Inflated; shaped like a parallelogram. Profile: Posterior end truncated with a negative slope (overhanging).
BOTTOM: Bottom shape: Very flat; slightly depressed at peristome. Deep rounded keel on bottom. Plastron: Large; protosternous plating.
AMB: Amb shape: Paired ambulacra are petaloid, wide, and open-ended. Unpaired ambulacrum is lanceolate, open-ended, and runs the entire length of the sulcus. Amb arrangement: Anterior paired ambulacra are flexuous and extend to the margin. Posterior paired ambulacra are much less flexed (more straight) and extend to the margin.
PORE PAIRS: Unpaired Amb: Small, round, and oblique. Paired Ambs: Outer pores only slightly elongated; inner pores more elongated. On all paired ambulacra, the posterior pore pairs are more widely spaced within the set.
TUBERCLES: Distribution: Very small and sparse aborally and adorally. Slightly larger near margins and along sides of anterior sulcus and apical system.
FASCIOLE: Marginal: Marginal fasciole present around the posterior of the test. No peripetalous fasciole.
APICAL SYSTEM: Location: Central. Shape: Elongated vertically. Genital pores: 4 genital pore pairs. Plating: Small madreporite.
PERIPROCT (ANUS): Shape: Oval; elongated vertically with pointed ends. Location: Situated just above the midpoint on the truncated posterior end. Visibility: Clearly visible from the rear; not visible from above.
PERISTOME (MOUTH): Shape: Horizontally oval (twice as wide as tall). Size: Small.
SPINES: Unknown.
SPECIMENS STUDIED & CONDITION: Holotype NPL 70936.
ETYMOLOGY
Named after the state of Texas.
REMARKS & COMPARISONS
Remarks: This species represents a rare occurrence of the genus in the Fredericksburg Group.
Comparisons:
- Pseudholaster sequanicus: P. texanus is wider and has a distinct negative sloping side near the periproct.
- Pseudholaster depressus: P. texanus has a much wider truncated shape.
