Nucleolites wilderae Ikins, 1940
Plate: NuWi-10
Series: Upper Cretaceous Group: Austin Formation: Dessau
Locale: Austin County: Travis Stage: Santonian
Length: 27.9 mm Width: 23.9 mm Height: 12.7 mm
Specimen in photos: UT 40535 Holotype
Collector: (Not specified)
Repository: Non-vertebrate Paleo. Lab., Univ. of Texas
HOLOTYPE INFO:
Holotype: UT 40535 (BEG 40535) (Ikins, 1940).
Locality: Little Walnut Creek, Austin, Travis County, Texas.
Stratigraphy: Dessau Formation ("Inoceramus undulato-plicatus zone"), Austin Group.
SYSTEMATIC PALEONTOLOGY – TAXONOMY
Class: Echinoidea Leske, 1778
Subclass: Euechinoidea Bronn, 1860
Infraclass: Irregularia Latreille, 1825
Superorder: Neognathostomata Smith, 1981
Order: Cassiduloida Claus, 1880
Family: Nucleolitidae L. Agassiz & Desor, 1847
Genus: NUCLEOLITES Lamarck, 1801
Species: Nucleolites wilderae Ikins, 1940
TYPE SPECIES: Nucleolites scutatus Lamarck, 1816
DIAGNOSIS
Test medium-sized, subovate to subquadrate, with a depressed, trapezoidal profile and concave base. Apical system anterior. Periproct situated in a deep, narrow sulcus on the aboral surface, extending to the posterior margin (Ikins, 1940).
STRATIGRAPHICAL OCCURRENCE & DISTRIBUTION
Group: Austin
Formations: Dessau Formation.
Stratigraphic Units: Upper Cretaceous, Santonian.
Counties: Travis.
Abundance: Rare; described from the holotype.
DESCRIPTION
TOP: Length, width, height: 27.9 mm L × 23.9 mm W × 12.7 mm H.
Top shape: Aborally oval with squared edges (subquadrate); wider at the posterior than the anterior. Widest spot is slightly posterior of center.
Top domed: Flat ridge on top.
SIDE: Side shape: Trapezoidal profile with a long flat ridge on top. Anterior end is rounded; posterior end is straighter/truncated.
Profile: Anterior slope is more abrupt than the posterior slope (Ikins, 1940).
BOTTOM: Bottom shape: Quite concave; deeply excavated (Ikins, 1940).
AMB: Amb shape: All five ambulacra are petaloid; pointed at the apical disc. The petals are narrow but widen again past the ambitus to the adoral surface.
Amb arrangement: Unpaired ambulacrum is slightly longer than the paired ambulacra. Petals are open distally (Ikins, 1940).
PORE PAIRS: Shape: Inner pores are rounder; outer pores are very elongated and oblique.
Arrangement: Pores are non-conjugate (Ikins, 1940).
TUBERCLES: Distribution: Tubercles are numerous, reducing in number near the ambulacra.
Areolas: Sunken.
Mamelons: Small.
GRANULES: Distribution: Interspaces occupied by microscopic granules (Ikins, 1940).
FASCIOLE: Absent in Nucleolites.
APICAL SYSTEM: Location: Anterior of center (Ikins, 1940).
Size: Small.
Genital pores: 4 gonopores.
PERIPROCT (ANUS): Location: Supramarginal (aboral surface); situated far from the apical system at nearly the same height.
Shape: Large (about 1/3 the height).
Features: Situated in a deep sulcus that cuts into the posterior margin (Ikins, 1940).
PERISTOME (MOUTH): Shape: Star-shaped (pentagonal); sub-central to slightly anterior (Ikins, 1940).
Size: Small; diameter about 1/9 of the test length.
SPINES: Unknown.
SPECIMENS STUDIED & CONDITION: Holotype UT 40535.
ETYMOLOGY
Named for Mrs. A. B. Wilder, who collected the holotype (Ikins, 1940).
REMARKS & COMPARISONS
Remarks: Ikins (1940) noted that this species is distinguished from Nucleolites texanus (Clark) by its larger size, different ambulacral proportions, and more pronounced anal sulcus.
Comparisons:
Plate: NuWi-10
Series: Upper Cretaceous Group: Austin Formation: Dessau
Locale: Austin County: Travis Stage: Santonian
Length: 27.9 mm Width: 23.9 mm Height: 12.7 mm
Specimen in photos: UT 40535 Holotype
Collector: (Not specified)
Repository: Non-vertebrate Paleo. Lab., Univ. of Texas
HOLOTYPE INFO:
Holotype: UT 40535 (BEG 40535) (Ikins, 1940).
Locality: Little Walnut Creek, Austin, Travis County, Texas.
Stratigraphy: Dessau Formation ("Inoceramus undulato-plicatus zone"), Austin Group.
SYSTEMATIC PALEONTOLOGY – TAXONOMY
Class: Echinoidea Leske, 1778
Subclass: Euechinoidea Bronn, 1860
Infraclass: Irregularia Latreille, 1825
Superorder: Neognathostomata Smith, 1981
Order: Cassiduloida Claus, 1880
Family: Nucleolitidae L. Agassiz & Desor, 1847
Genus: NUCLEOLITES Lamarck, 1801
Species: Nucleolites wilderae Ikins, 1940
TYPE SPECIES: Nucleolites scutatus Lamarck, 1816
DIAGNOSIS
Test medium-sized, subovate to subquadrate, with a depressed, trapezoidal profile and concave base. Apical system anterior. Periproct situated in a deep, narrow sulcus on the aboral surface, extending to the posterior margin (Ikins, 1940).
STRATIGRAPHICAL OCCURRENCE & DISTRIBUTION
Group: Austin
Formations: Dessau Formation.
Stratigraphic Units: Upper Cretaceous, Santonian.
Counties: Travis.
Abundance: Rare; described from the holotype.
DESCRIPTION
TOP: Length, width, height: 27.9 mm L × 23.9 mm W × 12.7 mm H.
Top shape: Aborally oval with squared edges (subquadrate); wider at the posterior than the anterior. Widest spot is slightly posterior of center.
Top domed: Flat ridge on top.
SIDE: Side shape: Trapezoidal profile with a long flat ridge on top. Anterior end is rounded; posterior end is straighter/truncated.
Profile: Anterior slope is more abrupt than the posterior slope (Ikins, 1940).
BOTTOM: Bottom shape: Quite concave; deeply excavated (Ikins, 1940).
AMB: Amb shape: All five ambulacra are petaloid; pointed at the apical disc. The petals are narrow but widen again past the ambitus to the adoral surface.
Amb arrangement: Unpaired ambulacrum is slightly longer than the paired ambulacra. Petals are open distally (Ikins, 1940).
PORE PAIRS: Shape: Inner pores are rounder; outer pores are very elongated and oblique.
Arrangement: Pores are non-conjugate (Ikins, 1940).
TUBERCLES: Distribution: Tubercles are numerous, reducing in number near the ambulacra.
Areolas: Sunken.
Mamelons: Small.
GRANULES: Distribution: Interspaces occupied by microscopic granules (Ikins, 1940).
FASCIOLE: Absent in Nucleolites.
APICAL SYSTEM: Location: Anterior of center (Ikins, 1940).
Size: Small.
Genital pores: 4 gonopores.
PERIPROCT (ANUS): Location: Supramarginal (aboral surface); situated far from the apical system at nearly the same height.
Shape: Large (about 1/3 the height).
Features: Situated in a deep sulcus that cuts into the posterior margin (Ikins, 1940).
PERISTOME (MOUTH): Shape: Star-shaped (pentagonal); sub-central to slightly anterior (Ikins, 1940).
Size: Small; diameter about 1/9 of the test length.
SPINES: Unknown.
SPECIMENS STUDIED & CONDITION: Holotype UT 40535.
ETYMOLOGY
Named for Mrs. A. B. Wilder, who collected the holotype (Ikins, 1940).
REMARKS & COMPARISONS
Remarks: Ikins (1940) noted that this species is distinguished from Nucleolites texanus (Clark) by its larger size, different ambulacral proportions, and more pronounced anal sulcus.
Comparisons:
- N. texanus: N. wilderae is larger and has a deeper, more marginal anal groove than N. texanus.
