Mellita quinquiesperforata (Leske, 1778)
Plate: MeQu-10
Series: Holocene Group: Undifferentiated Quaternary Formation: Barrier Island Deposits
Locale: Corpus Christi County: Nueces Stage: Northgrippian or Greenlandian
Length: 36.3 mm Width: 37.4 mm Height: 7.2 mm
Specimen in photos: Collection of Paul Hammerschmidt
Repository: Private Collection
HOLOTYPE INFO:
Holotype: Leske’s original material is likely lost. Harold & Telford (1990) designated a Neotype (USNM 8882).
Type Locality: Restricted to Veracruz, Mexico by Harold & Telford (1990).
Stratigraphy: Recent / Holocene (Existing species with Pleistocene fossil record).
SYNONYMY
SYSTEMATIC PALEONTOLOGY – TAXONOMY
Class: Echinoidea Leske, 1778
Subclass: Euechinoidea Bronn, 1860
Infraclass: Irregularia Latreille, 1825
Superorder: Neognathostomata Smith, 1981
Order: Clypeasteroida A. Agassiz, 1872
Family: Mellitidae Stefanini, 1912
Genus: MELLITA L. Agassiz, 1841
Species: Mellita quinquiesperforata (Leske, 1778)
TYPE SPECIES: Echinodiscus quinquiesperforatus Leske, 1778
DIAGNOSIS
Test large, very flat, and subcircular to transversely oval. Characterized by five closed lunules (four paired ambulacral lunules and one longer posterior interambulacral lunule). The apical system is slightly anterior of center, distinguishing it from M. tenuis. Possesses four genital pores (Harold & Telford, 1990).
STRATIGRAPHICAL OCCURRENCE & DISTRIBUTION
Group: Undifferentiated Coastal Deposits
Formations: Barrier Island Deposits
Stratigraphic Units: Holocene
Counties: Aransas, Nueces, Galveston, Jefferson.
Abundance: Hard to find.
DESCRIPTION
TOP: Length, width, height: 36.3 mm L × 37.4 mm W × 7.2 mm H.
Top shape: Subcircular; usually flattened behind and weakly notched in front (Cooke, 1942).
Top domed: Upper surface nearly flat, sloping evenly in all directions from the apical system to the margin; highest point is the apical system (Cooke, 1942).
SIDE: Side shape: Margin very thin and acute (Cooke, 1942).
BOTTOM: Bottom shape: Flat (Cooke, 1942).
AMB: Amb shape: Petaloid area is small (less than half the test length). Petals extend about halfway to the margin.
Amb arrangement: Anterior paired petals are slightly shorter and rounder than the others (Cooke, 1942). Paired petals are generally straight.
Lunules: Test perforated by narrow radial slots (lunules) near the outer ends of the paired ambulacra.
INTERAMB: Lunule: A longer slot (anal lunule) is present in the median part of the posterior interambulacrum (Cooke, 1942).
PORE PAIRS: Arrangement: Poriferous zones are about as wide as the interporiferous zones; open at the rounded tips (Cooke, 1942).
Shape: Pores oval and conjugate.
TUBERCLES: Distribution: Surface covered with short acicular spines (in life), which are longest around the perforations and on the lower surface (Cooke, 1942).
GRANULES: See Tubercles.
FASCIOLE: Absent.
APICAL SYSTEM: Location: Slightly anterior of center (Harold & Telford, 1990).
Genital pores: Four genital pores at the paired interambulacral tips of the large star-shaped madreporite (Cooke, 1942).
Plating: Five small ocular pores present (Cooke, 1942).
PERIPROCT (ANUS): Shape: Elongated (oval).
Location: Oral surface (bottom); situated midway between the peristome and the posterior slot (anal lunule) (Cooke, 1942). Note: In M. tenuis, this is often closer to the lunule.
PERISTOME (MOUTH): Size: Small.
Location: Central.
Features: Food grooves are narrow and shallow, divaricating near the peristome; branches nearly surround the ambulacra (Cooke, 1942).
SPINES: See Tubercles section.
SPECIMENS STUDIED & CONDITION: One specimen studied from the Collection of Paul Hammerschmidt. Edges are damaged, causing closed lunules to appear as open notches (Book Author).
ETYMOLOGY
From the Latin quinque (five) + perforata (holes/perforations), referring to the five lunules.
REMARKS & COMPARISONS
Remarks: This species is the type for the genus Mellita. Pleistocene specimens are often noted to be significantly larger (50–100% larger) than their modern counterparts (Cooke, 1942).
Comparisons:
Plate: MeQu-10
Series: Holocene Group: Undifferentiated Quaternary Formation: Barrier Island Deposits
Locale: Corpus Christi County: Nueces Stage: Northgrippian or Greenlandian
Length: 36.3 mm Width: 37.4 mm Height: 7.2 mm
Specimen in photos: Collection of Paul Hammerschmidt
Repository: Private Collection
HOLOTYPE INFO:
Holotype: Leske’s original material is likely lost. Harold & Telford (1990) designated a Neotype (USNM 8882).
Type Locality: Restricted to Veracruz, Mexico by Harold & Telford (1990).
Stratigraphy: Recent / Holocene (Existing species with Pleistocene fossil record).
SYNONYMY
- Echinodiscus quinquiesperforatus Leske, 1778
- Mellita testudinata Klein, 1734 (Pre-Linnean; invalid)
- Mellita pentapora Gmelin, 1791
- Mellita ampla Holmes, 1860
SYSTEMATIC PALEONTOLOGY – TAXONOMY
Class: Echinoidea Leske, 1778
Subclass: Euechinoidea Bronn, 1860
Infraclass: Irregularia Latreille, 1825
Superorder: Neognathostomata Smith, 1981
Order: Clypeasteroida A. Agassiz, 1872
Family: Mellitidae Stefanini, 1912
Genus: MELLITA L. Agassiz, 1841
Species: Mellita quinquiesperforata (Leske, 1778)
TYPE SPECIES: Echinodiscus quinquiesperforatus Leske, 1778
DIAGNOSIS
Test large, very flat, and subcircular to transversely oval. Characterized by five closed lunules (four paired ambulacral lunules and one longer posterior interambulacral lunule). The apical system is slightly anterior of center, distinguishing it from M. tenuis. Possesses four genital pores (Harold & Telford, 1990).
STRATIGRAPHICAL OCCURRENCE & DISTRIBUTION
Group: Undifferentiated Coastal Deposits
Formations: Barrier Island Deposits
Stratigraphic Units: Holocene
Counties: Aransas, Nueces, Galveston, Jefferson.
Abundance: Hard to find.
DESCRIPTION
TOP: Length, width, height: 36.3 mm L × 37.4 mm W × 7.2 mm H.
Top shape: Subcircular; usually flattened behind and weakly notched in front (Cooke, 1942).
Top domed: Upper surface nearly flat, sloping evenly in all directions from the apical system to the margin; highest point is the apical system (Cooke, 1942).
SIDE: Side shape: Margin very thin and acute (Cooke, 1942).
BOTTOM: Bottom shape: Flat (Cooke, 1942).
AMB: Amb shape: Petaloid area is small (less than half the test length). Petals extend about halfway to the margin.
Amb arrangement: Anterior paired petals are slightly shorter and rounder than the others (Cooke, 1942). Paired petals are generally straight.
Lunules: Test perforated by narrow radial slots (lunules) near the outer ends of the paired ambulacra.
INTERAMB: Lunule: A longer slot (anal lunule) is present in the median part of the posterior interambulacrum (Cooke, 1942).
PORE PAIRS: Arrangement: Poriferous zones are about as wide as the interporiferous zones; open at the rounded tips (Cooke, 1942).
Shape: Pores oval and conjugate.
TUBERCLES: Distribution: Surface covered with short acicular spines (in life), which are longest around the perforations and on the lower surface (Cooke, 1942).
GRANULES: See Tubercles.
FASCIOLE: Absent.
APICAL SYSTEM: Location: Slightly anterior of center (Harold & Telford, 1990).
Genital pores: Four genital pores at the paired interambulacral tips of the large star-shaped madreporite (Cooke, 1942).
Plating: Five small ocular pores present (Cooke, 1942).
PERIPROCT (ANUS): Shape: Elongated (oval).
Location: Oral surface (bottom); situated midway between the peristome and the posterior slot (anal lunule) (Cooke, 1942). Note: In M. tenuis, this is often closer to the lunule.
PERISTOME (MOUTH): Size: Small.
Location: Central.
Features: Food grooves are narrow and shallow, divaricating near the peristome; branches nearly surround the ambulacra (Cooke, 1942).
SPINES: See Tubercles section.
SPECIMENS STUDIED & CONDITION: One specimen studied from the Collection of Paul Hammerschmidt. Edges are damaged, causing closed lunules to appear as open notches (Book Author).
ETYMOLOGY
From the Latin quinque (five) + perforata (holes/perforations), referring to the five lunules.
REMARKS & COMPARISONS
Remarks: This species is the type for the genus Mellita. Pleistocene specimens are often noted to be significantly larger (50–100% larger) than their modern counterparts (Cooke, 1942).
Comparisons:
- Mellita tenuis: M. quinquiesperforata is distinguished by having the apical system positioned anterior of center (eccentric anteriorly), whereas M. tenuis has the apical system positioned posterior of center (Harold & Telford, 1990). M. tenuis is also typically thinner.
- Mellita lata: M. quinquiesperforata is less broadly oval/transverse than M. lata.
- Leodia sexiesperforata: Distinguished by having only 5 lunules (lacking the anterior unpaired lunule of Leodia).
