Pseudodiadema aguilerai (Maldonado-Koerdell, 1953)
Plate: PsAg-10
Series: Lower Cretaceous Group: Trinity Formation: Glen Rose
Locale: Canyon Lake County: Comal Stage: Early Albian
Length: 39.0 mm Height: 13.3 mm
Specimen in photo: NPL 83040 Hypotype
Collector: William R. Thompson, Jr.
Repository: Non-vertebrate Paleo. Lab., Univ. of Texas
HOLOTYPE INFO:
Holotype: C.P.N. 593 (Colección Paleontológica Nacional, Mexico) (Maldonado-Koerdell, 1953).
Locality: San Juan Raya, Puebla, Mexico.
Stratigraphy: San Juan Raya Formation (Aptian).
SYNONYMY
SYSTEMATIC PALEONTOLOGY – TAXONOMY
Class: Echinoidea Leske, 1778
Subclass: Euechinoidea Bronn, 1860
Infraclass: Carinacea Kroh & Smith, 2010
Superorder: Calycina Gregory, 1900
Order: Phymosomatoida Mortensen, 1904
Family: Polydiadematidae Lambert, 1900
Genus: PSEUDODIADEMA Desor, 1855
Species: Pseudodiadema aguilerai (Maldonado-Koerdell, 1953)
TYPE SPECIES: Cidaris pseudodiadema Lamarck, 1816
DIAGNOSIS
Test medium-sized, subhemispherical to sub-pentagonal. Characterized by perforate, crenulate tubercles and a dicyclic apical system. Ambulacral pores are uniserial adapically but form distinct phyllodes (crowding) near the peristome. Distinguished from Loriolia by the lack of dense, uniform granulation and the dicyclic apical disc (Smith & Rader, 2009).
STRATIGRAPHICAL OCCURRENCE & DISTRIBUTION
Group: Trinity
Formations: Glen Rose Formation (Texas); San Juan Raya Formation (Mexico).
Stratigraphic Units: Lower Cretaceous, Albian.
Counties: Comal, Hays.
Abundance: Uncommon.
DESCRIPTION
TOP: Length, width, height: 39.0 mm L × 13.3 mm H (Hypotype NPL 83040). Top shape: Circular. Top domed: Rounded top.
SIDE: Ambitus: Positioned below midpoint. Side shape: Sides slightly curved below ambitus; inflated.
BOTTOM: Bottom shape: Flattened.
AMB: Amb shape: Lanceolate; slightly widens starting at midpoint. Amb arrangement: Near the apical disc, where ambulacra are narrow, tubercles are very small compared to the interambulacral tubercles (which are up to 10 times larger).
PORE PAIRS: Arrangement: Uniserial until near the peristome where they crowd greatly to form strong phyllodes (Smith & Rader, 2009). Shape: Pore pairs have a pronounced bump (interporal granule) between pores.
TUBERCLES: Primary Perforated: Yes. Primary Crenulate: Yes (crenulations very pronounced). Interambulacral Tubercles: Above ambitus, interamb tubercles are twice the size of those in the ambs. Below ambitus, they are only slightly larger. Scrobicular Tubercles: Each primary tubercle has scrobicular tubercles creating a ridge at interradial and adradial sutures.
GRANULES: Distribution: Test naked of granules above each peristomial lip.
FASCIOLE: Absent.
INTERAMB: Width: About 20% wider than ambulacra. Arrangement: Plates hexagonal; top and bottom of each plate parallel. Areolas cover a large part of each plate and are very pronounced.
APICAL SYSTEM: Type: Dicyclic (Smith & Rader, 2009). Size: Occupies about 22% of test diameter; flush with test. Plating: Genital plates are 8-sided with ~10 granules and a pore near the outer point. Oculars are very small, "C" shaped, concave on outer edges, with 3 granules each. Madreporite is very large (covers ~70% of genital plate).
PERIPROCT (ANUS): Shape: Large, pentagonal. Size: Occupies about 60% of the apical system. Lip: Not raised.
PERISTOME (MOUTH): Size: Large; diameter about 55% of test. Lip: Buccal notches deep; largest side of each lip is away from ambs. Phyllodes: Strong.
SPINES: Unknown.
SPECIMENS STUDIED & CONDITION: Hypotype NPL 83040. A juvenile specimen (8.9 mm) found in Comal County by Kevin Durney (Georgetown, TX).
ETYMOLOGY
Named in honor of José Guadalupe Aguilera (1857–1941), Mexican geologist and director of the Instituto Geológico de México (Maldonado-Koerdell, 1953).
REMARKS & COMPARISONS
Remarks: This species was originally placed in Loriolia by Maldonado-Koerdell (1953) but moved to Pseudodiadema by Smith & Rader (2009) due to the dicyclic apical system and phyllode development.
Comparisons:
Plate: PsAg-10
Series: Lower Cretaceous Group: Trinity Formation: Glen Rose
Locale: Canyon Lake County: Comal Stage: Early Albian
Length: 39.0 mm Height: 13.3 mm
Specimen in photo: NPL 83040 Hypotype
Collector: William R. Thompson, Jr.
Repository: Non-vertebrate Paleo. Lab., Univ. of Texas
HOLOTYPE INFO:
Holotype: C.P.N. 593 (Colección Paleontológica Nacional, Mexico) (Maldonado-Koerdell, 1953).
Locality: San Juan Raya, Puebla, Mexico.
Stratigraphy: San Juan Raya Formation (Aptian).
SYNONYMY
- Loriolia aguilerai Maldonado-Koerdell, 1953
- Pseudodiadema sp. cf. P. aguilerai (Maldonado-Koerdell) Smith & Rader, 2009
SYSTEMATIC PALEONTOLOGY – TAXONOMY
Class: Echinoidea Leske, 1778
Subclass: Euechinoidea Bronn, 1860
Infraclass: Carinacea Kroh & Smith, 2010
Superorder: Calycina Gregory, 1900
Order: Phymosomatoida Mortensen, 1904
Family: Polydiadematidae Lambert, 1900
Genus: PSEUDODIADEMA Desor, 1855
Species: Pseudodiadema aguilerai (Maldonado-Koerdell, 1953)
TYPE SPECIES: Cidaris pseudodiadema Lamarck, 1816
DIAGNOSIS
Test medium-sized, subhemispherical to sub-pentagonal. Characterized by perforate, crenulate tubercles and a dicyclic apical system. Ambulacral pores are uniserial adapically but form distinct phyllodes (crowding) near the peristome. Distinguished from Loriolia by the lack of dense, uniform granulation and the dicyclic apical disc (Smith & Rader, 2009).
STRATIGRAPHICAL OCCURRENCE & DISTRIBUTION
Group: Trinity
Formations: Glen Rose Formation (Texas); San Juan Raya Formation (Mexico).
Stratigraphic Units: Lower Cretaceous, Albian.
Counties: Comal, Hays.
Abundance: Uncommon.
DESCRIPTION
TOP: Length, width, height: 39.0 mm L × 13.3 mm H (Hypotype NPL 83040). Top shape: Circular. Top domed: Rounded top.
SIDE: Ambitus: Positioned below midpoint. Side shape: Sides slightly curved below ambitus; inflated.
BOTTOM: Bottom shape: Flattened.
AMB: Amb shape: Lanceolate; slightly widens starting at midpoint. Amb arrangement: Near the apical disc, where ambulacra are narrow, tubercles are very small compared to the interambulacral tubercles (which are up to 10 times larger).
PORE PAIRS: Arrangement: Uniserial until near the peristome where they crowd greatly to form strong phyllodes (Smith & Rader, 2009). Shape: Pore pairs have a pronounced bump (interporal granule) between pores.
TUBERCLES: Primary Perforated: Yes. Primary Crenulate: Yes (crenulations very pronounced). Interambulacral Tubercles: Above ambitus, interamb tubercles are twice the size of those in the ambs. Below ambitus, they are only slightly larger. Scrobicular Tubercles: Each primary tubercle has scrobicular tubercles creating a ridge at interradial and adradial sutures.
GRANULES: Distribution: Test naked of granules above each peristomial lip.
FASCIOLE: Absent.
INTERAMB: Width: About 20% wider than ambulacra. Arrangement: Plates hexagonal; top and bottom of each plate parallel. Areolas cover a large part of each plate and are very pronounced.
APICAL SYSTEM: Type: Dicyclic (Smith & Rader, 2009). Size: Occupies about 22% of test diameter; flush with test. Plating: Genital plates are 8-sided with ~10 granules and a pore near the outer point. Oculars are very small, "C" shaped, concave on outer edges, with 3 granules each. Madreporite is very large (covers ~70% of genital plate).
PERIPROCT (ANUS): Shape: Large, pentagonal. Size: Occupies about 60% of the apical system. Lip: Not raised.
PERISTOME (MOUTH): Size: Large; diameter about 55% of test. Lip: Buccal notches deep; largest side of each lip is away from ambs. Phyllodes: Strong.
SPINES: Unknown.
SPECIMENS STUDIED & CONDITION: Hypotype NPL 83040. A juvenile specimen (8.9 mm) found in Comal County by Kevin Durney (Georgetown, TX).
ETYMOLOGY
Named in honor of José Guadalupe Aguilera (1857–1941), Mexican geologist and director of the Instituto Geológico de México (Maldonado-Koerdell, 1953).
REMARKS & COMPARISONS
Remarks: This species was originally placed in Loriolia by Maldonado-Koerdell (1953) but moved to Pseudodiadema by Smith & Rader (2009) due to the dicyclic apical system and phyllode development.
Comparisons:
- Loriolia rosana: P. aguilerai is distinguished by its dicyclic apical system (vs. monocyclic/pentagonal in Loriolia) and the lack of the dense, uniform "sandy" granulation characteristic of Loriolia.
- Polydiadema: Differentiated by the crowding of pore pairs (phyllodes) near the peristome, which is less developed or absent in Polydiadema (Smith & Rader, 2009).
