Coenholectypus engerrandi Lambert, 1927
Plate: CoEn-10
Series: Lower Cretaceous Group: Fredericksburg Formation: Walnut
Locale: Bee Cave County: Travis Stage: Albian
Length: 21.8 mm Height: 13.4 mm
Specimen in photo: NPL 82997 (Hypotype)
Repository: Non-vertebrate Paleo. Lab., Univ. of Texas
HOLOTYPE INFO:
Holotype: Originally in the collection of W.S. Adkins; likely housed at the Bureau of Economic Geology (BEG) or NPL, University of Texas (Lambert, 1927).
Locality: West of Austin, Travis County, Texas (Lambert, 1927).
Systematic Paleontology
CLASS: ECHINOIDEA Leske, 1778
SUBCLASS: EUECHINOIDEA Bronn, 1860
INFRACLASS: IRREGULARIA Latreille, 1825
SUPERORDER: GNATHOSTOMATA Zittel, 1879
ORDER: HOLECTYPOIDA Duncan, 1889
FAMILY: COENHOLECTYPIDAE Smith & Wright, 1999
GENUS: COENHOLECTYPUS Pomel, 1883
SPECIES: Coenholectypus engerrandi (Lambert, 1927)
TYPE SPECIES: Discoidea depressa L. Agassiz, 1839
STRATIGRAPHICAL OCCURRENCE & DISTRIBUTION
Group: Fredericksburg
Formations: Walnut Formation
Stratigraphic Units: Lower Cretaceous, Albian
Counties: Travis County
DESCRIPTION
TOP: Length, height: 21.8 mm L ×13.4 mm H
Top shape: Pentagonal; globular above ; Subconical (Lambert, 1927)
Top domed: Slight point at apical system
SIDE: Ambitus: Very near bottom
Side shape: Globular above; ambitus low
BOTTOM: Bottom flat: Large flat adoral surface
AMB: Amb shape: Lanceolate
Amb primary tubercles: Six tubercles at ambitus
INTERAMB: Interamb size: 30% bigger than ambulacra
Interamb primary tubercles: 12 tubercles at ambitus
PORE PAIRS: Shape: Round; very small
TUBERCLES: Primary tubercles: Finely crenulated, perforated; larger near and on adoral surface
Primary Perforated: Yes
Primary Crenulate: Yes
Secondary tubercles: Minute scrobicular tubercles surround larger tubercles
APICAL SYSTEM: Size / Location: Very small
Genital pores: 5 gonopores
PERIPROCT (ANUS): Shape & Size: Teardrop shaped (pyriform), pointed end pointing to peristome; very large
Location: Infra-marginal (on bottom); covers almost entire area from ambitus to peristome
PERISTOME (MOUTH): Size: Diameter 25% of diameter of test
Shape: Slightly ovate
SPECIMENS STUDIED & CONDITION: Hypotype NPL 82997 studied .
ETYMOLOGY: Named in honor of George C. Engerrand (1877–1961), a geologist and professor at the University of Texas (Lambert, 1927).
REMARKS & COMPARISONS
Remarks: Coenholectypus engerrandi is characterized by its distinctly pentagonal outline and subconical profile. While Smith & Kroh (2011) list this species as a synonym of Coenholectypus planatus (Roemer), Thompson (2016) retains it as a valid species based on morphological differences (specifically the pentagonal shape and low ambitus).
Comparisons: Lambert (1927) distinguished C. engerrandi from C. planatus by its smaller size, more pentagonal form, and more conical upper surface. The periproct occupies the entire oral radius (ambitus to peristome), a feature shared with C. planatus and C. adkinsi.
Plate: CoEn-10
Series: Lower Cretaceous Group: Fredericksburg Formation: Walnut
Locale: Bee Cave County: Travis Stage: Albian
Length: 21.8 mm Height: 13.4 mm
Specimen in photo: NPL 82997 (Hypotype)
Repository: Non-vertebrate Paleo. Lab., Univ. of Texas
HOLOTYPE INFO:
Holotype: Originally in the collection of W.S. Adkins; likely housed at the Bureau of Economic Geology (BEG) or NPL, University of Texas (Lambert, 1927).
Locality: West of Austin, Travis County, Texas (Lambert, 1927).
Systematic Paleontology
CLASS: ECHINOIDEA Leske, 1778
SUBCLASS: EUECHINOIDEA Bronn, 1860
INFRACLASS: IRREGULARIA Latreille, 1825
SUPERORDER: GNATHOSTOMATA Zittel, 1879
ORDER: HOLECTYPOIDA Duncan, 1889
FAMILY: COENHOLECTYPIDAE Smith & Wright, 1999
GENUS: COENHOLECTYPUS Pomel, 1883
SPECIES: Coenholectypus engerrandi (Lambert, 1927)
TYPE SPECIES: Discoidea depressa L. Agassiz, 1839
STRATIGRAPHICAL OCCURRENCE & DISTRIBUTION
Group: Fredericksburg
Formations: Walnut Formation
Stratigraphic Units: Lower Cretaceous, Albian
Counties: Travis County
DESCRIPTION
TOP: Length, height: 21.8 mm L ×13.4 mm H
Top shape: Pentagonal; globular above ; Subconical (Lambert, 1927)
Top domed: Slight point at apical system
SIDE: Ambitus: Very near bottom
Side shape: Globular above; ambitus low
BOTTOM: Bottom flat: Large flat adoral surface
AMB: Amb shape: Lanceolate
Amb primary tubercles: Six tubercles at ambitus
INTERAMB: Interamb size: 30% bigger than ambulacra
Interamb primary tubercles: 12 tubercles at ambitus
PORE PAIRS: Shape: Round; very small
TUBERCLES: Primary tubercles: Finely crenulated, perforated; larger near and on adoral surface
Primary Perforated: Yes
Primary Crenulate: Yes
Secondary tubercles: Minute scrobicular tubercles surround larger tubercles
APICAL SYSTEM: Size / Location: Very small
Genital pores: 5 gonopores
PERIPROCT (ANUS): Shape & Size: Teardrop shaped (pyriform), pointed end pointing to peristome; very large
Location: Infra-marginal (on bottom); covers almost entire area from ambitus to peristome
PERISTOME (MOUTH): Size: Diameter 25% of diameter of test
Shape: Slightly ovate
SPECIMENS STUDIED & CONDITION: Hypotype NPL 82997 studied .
ETYMOLOGY: Named in honor of George C. Engerrand (1877–1961), a geologist and professor at the University of Texas (Lambert, 1927).
REMARKS & COMPARISONS
Remarks: Coenholectypus engerrandi is characterized by its distinctly pentagonal outline and subconical profile. While Smith & Kroh (2011) list this species as a synonym of Coenholectypus planatus (Roemer), Thompson (2016) retains it as a valid species based on morphological differences (specifically the pentagonal shape and low ambitus).
Comparisons: Lambert (1927) distinguished C. engerrandi from C. planatus by its smaller size, more pentagonal form, and more conical upper surface. The periproct occupies the entire oral radius (ambitus to peristome), a feature shared with C. planatus and C. adkinsi.
