Washitaster riovistae wenoensis (Adkins, 1920)
Plate: WaRiWe-10
Series: Lower Cretaceous Group: Washita Formation: Upper Weno
Locale: Rio Vista County: Johnson Stage: Albian
Length: 25.3 mm Width: 23.1 mm Height: 14.6 mm
Specimen in photos: BEG 21496 Holotype
Collector: (Not specified)
Repository: Non-vertebrate Paleo. Lab., Univ. of Texas
HOLOTYPE INFO:
Holotype: BEG 21496 (Adkins, 1920).
Locality: Locality 720; one mile southeast of Rio Vista, Johnson County, Texas.
Stratigraphy: Upper five feet of Weno Formation (marl facies).
SYNONYMY
SYSTEMATIC PALEONTOLOGY – TAXONOMY
Class: Echinoidea Leske, 1778
Subclass: Euechinoidea Bronn, 1860
Infraclass: Irregularia Latreille, 1825
Superorder: Atelostomata Zittel, 1879
Order: Spatangoida L. Agassiz, 1840
Family: Toxasteridae Lambert, 1920
Genus: WASHITASTER Lambert, 1927
Species: Washitaster riovistae (Adkins, 1920)
Subspecies: Washitaster riovistae wenoensis (Adkins, 1920)
TYPE SPECIES: Hemiaster riovistae Adkins, 1920
DIAGNOSIS
According to Adkins (1920): Test ovate, inflated, and rotund; less elongate and more abruptly truncated posteriorly than W. riovistae. Distinguished by a deep, vertical excavation on the posterior face containing the periproct, and a sharp, deep anterior ambital notch.
STRATIGRAPHICAL OCCURRENCE & DISTRIBUTION
Group: Washita
Formations: Weno Formation (Upper 5 feet); Pawpaw Formation (Base).
Stratigraphic Units: Lower Cretaceous, Albian.
Counties: Johnson, Tarrant.
Abundance: Common in the marl facies of the Weno.
Associated Fauna: Enallaster bravoensis, Hemiaster calvini, Holaster sp. aff. simplex (Adkins, 1920).
DESCRIPTION (Based on Adkins, 1920)
TOP: Length, width, height: 25.3 mm L × 23.1 mm W × 14.6 mm H (Image). Type Dims: 25.0 x 23.4 x 14.3 mm. Top shape: Ovate with angulations; broadest point anterior to the center. Anterior corners broadly rounded to the notch of the anterior sulcus. Top domed: Aborally, the highest point is on the carina midway between the posterior ends of the short posterolateral ambulacra; test slopes gently anteriorly from this point.
SIDE: Side shape: Inflated; anteriorly wedge-shaped. Posterior corners on the ambitus are abruptly rounded to the excavated periproct area. Profile: Most prominent point inferiorly is on the mid-line three-fourths the way back from the anterior end.
BOTTOM: Bottom shape: Oral surface inflated medially.
AMB: Amb shape: Unpaired anterior ambulacrum (III) sunk in a deep anterior sulcus (relatively shorter and narrower than in W. riovistae). Paired Anterolaterals (II & IV): Diverge at 180°, turn forward (middle parts make angle of ~45°), then turn laterally to cross the ambitus posterior to the anterior corner. Paired Posterolaterals (I & V): Short, inflated centrally; diverge at ~130°.
PORE PAIRS: Unpaired Amb: About 31 pairs. First 12 pairs short/equal; next 5 pairs alternating (3 long, 2 short); next 2 groups of 2 short pairs alternating with long pairs; thereafter anteriorly pores are short. Short pairs are separated by a tubercle. Anterolaterals: Anterior zone has 18–20 small circular pore pairs. Posterior zone has ~27 slit-like pairs. Posterolaterals: ~12 pairs per zone; posterior zone pores more elongate than anterior zone.
TUBERCLES: Distribution: Narrow ambulacral plates have two transverse rows of variable sized tubercles, irregularly arranged.
GRANULES: Not detailed
FASCIOLE: Not detailed, but Washitaster is defined by fasciole bands.
APICAL SYSTEM: Location: Little less than two-thirds the way back on the mid-line. Genital pores: Four genital plates with conspicuous thick-lipped perforations forming a square.
PERIPROCT (ANUS): Shape: Ovoid; inferior margin extended downward. Location: Situated at the top of a vertically excavated area in the posterior truncated area (Diagnostic).
PERISTOME (MOUTH): Shape: Ovoid, depressed. Lip: Posterior lip straight, with an elevated median carina behind it.
SPINES: Unknown.
SPECIMENS STUDIED & CONDITION: Holotype BEG 21496.
ETYMOLOGY
Named for the Weno Formation, the stratigraphic unit where the holotype was found.
REMARKS & COMPARISONS
Comparisons (per Adkins, 1920):
Plate: WaRiWe-10
Series: Lower Cretaceous Group: Washita Formation: Upper Weno
Locale: Rio Vista County: Johnson Stage: Albian
Length: 25.3 mm Width: 23.1 mm Height: 14.6 mm
Specimen in photos: BEG 21496 Holotype
Collector: (Not specified)
Repository: Non-vertebrate Paleo. Lab., Univ. of Texas
HOLOTYPE INFO:
Holotype: BEG 21496 (Adkins, 1920).
Locality: Locality 720; one mile southeast of Rio Vista, Johnson County, Texas.
Stratigraphy: Upper five feet of Weno Formation (marl facies).
SYNONYMY
- Enallaster wenoensis Adkins, 1920
- Washitaster wenoensis (Adkins) Lambert, 1927
- Enallaster riovistae var. wenoensis (Adkins)
SYSTEMATIC PALEONTOLOGY – TAXONOMY
Class: Echinoidea Leske, 1778
Subclass: Euechinoidea Bronn, 1860
Infraclass: Irregularia Latreille, 1825
Superorder: Atelostomata Zittel, 1879
Order: Spatangoida L. Agassiz, 1840
Family: Toxasteridae Lambert, 1920
Genus: WASHITASTER Lambert, 1927
Species: Washitaster riovistae (Adkins, 1920)
Subspecies: Washitaster riovistae wenoensis (Adkins, 1920)
TYPE SPECIES: Hemiaster riovistae Adkins, 1920
DIAGNOSIS
According to Adkins (1920): Test ovate, inflated, and rotund; less elongate and more abruptly truncated posteriorly than W. riovistae. Distinguished by a deep, vertical excavation on the posterior face containing the periproct, and a sharp, deep anterior ambital notch.
STRATIGRAPHICAL OCCURRENCE & DISTRIBUTION
Group: Washita
Formations: Weno Formation (Upper 5 feet); Pawpaw Formation (Base).
Stratigraphic Units: Lower Cretaceous, Albian.
Counties: Johnson, Tarrant.
Abundance: Common in the marl facies of the Weno.
Associated Fauna: Enallaster bravoensis, Hemiaster calvini, Holaster sp. aff. simplex (Adkins, 1920).
DESCRIPTION (Based on Adkins, 1920)
TOP: Length, width, height: 25.3 mm L × 23.1 mm W × 14.6 mm H (Image). Type Dims: 25.0 x 23.4 x 14.3 mm. Top shape: Ovate with angulations; broadest point anterior to the center. Anterior corners broadly rounded to the notch of the anterior sulcus. Top domed: Aborally, the highest point is on the carina midway between the posterior ends of the short posterolateral ambulacra; test slopes gently anteriorly from this point.
SIDE: Side shape: Inflated; anteriorly wedge-shaped. Posterior corners on the ambitus are abruptly rounded to the excavated periproct area. Profile: Most prominent point inferiorly is on the mid-line three-fourths the way back from the anterior end.
BOTTOM: Bottom shape: Oral surface inflated medially.
AMB: Amb shape: Unpaired anterior ambulacrum (III) sunk in a deep anterior sulcus (relatively shorter and narrower than in W. riovistae). Paired Anterolaterals (II & IV): Diverge at 180°, turn forward (middle parts make angle of ~45°), then turn laterally to cross the ambitus posterior to the anterior corner. Paired Posterolaterals (I & V): Short, inflated centrally; diverge at ~130°.
PORE PAIRS: Unpaired Amb: About 31 pairs. First 12 pairs short/equal; next 5 pairs alternating (3 long, 2 short); next 2 groups of 2 short pairs alternating with long pairs; thereafter anteriorly pores are short. Short pairs are separated by a tubercle. Anterolaterals: Anterior zone has 18–20 small circular pore pairs. Posterior zone has ~27 slit-like pairs. Posterolaterals: ~12 pairs per zone; posterior zone pores more elongate than anterior zone.
TUBERCLES: Distribution: Narrow ambulacral plates have two transverse rows of variable sized tubercles, irregularly arranged.
GRANULES: Not detailed
FASCIOLE: Not detailed, but Washitaster is defined by fasciole bands.
APICAL SYSTEM: Location: Little less than two-thirds the way back on the mid-line. Genital pores: Four genital plates with conspicuous thick-lipped perforations forming a square.
PERIPROCT (ANUS): Shape: Ovoid; inferior margin extended downward. Location: Situated at the top of a vertically excavated area in the posterior truncated area (Diagnostic).
PERISTOME (MOUTH): Shape: Ovoid, depressed. Lip: Posterior lip straight, with an elevated median carina behind it.
SPINES: Unknown.
SPECIMENS STUDIED & CONDITION: Holotype BEG 21496.
ETYMOLOGY
Named for the Weno Formation, the stratigraphic unit where the holotype was found.
REMARKS & COMPARISONS
Comparisons (per Adkins, 1920):
- Washitaster riovistae: W. wenoensis is broader, less elongate, more nearly circular, and distinctly less flat. The periproct area in wenoensis is sharply excavated giving a narrow vertical groove, whereas riovistae is broadly truncate/shallow. The apical system is farther forward in wenoensis.
- Washitaster bravoensis: W. wenoensis is more ovate and lacks the long posterior narrowing of bravoensis. The anterior ambital notch is sharper and deeper in wenoensis. The highest point in wenoensis is midway between the apical system and posterior end (vs. variable/near apical system in bravoensis).
