Pygolampas edita
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publication ID |
https://doi.org/ 10.5281/zenodo.282522 |
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DOI |
https://doi.org/10.5281/zenodo.5694041 |
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persistent identifier |
https://treatment.plazi.org/id/03E487FA-FF89-FFE2-FF2E-FE88FB62FF6F |
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treatment provided by |
Plazi |
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scientific name |
Pygolampas edita |
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Pygolampas edita View in CoL gen. et sp. nov.
Figures 4 A View FIGURE 4. A – E –F and 5 A–B
Holotype. The holotype and only known specimen is GR-PC.1709. It is housed in collections of the department of Earth Sciences, Géosciences, Université de Rennes 1 (Rennes, France).
Type locality. Collected by P. Courville near Narcy (48°58’N, 05°10’E), Haute Marne, France; Early Cretaceous, Hauterivian, Acanthodiscus radiatus chronozone, Calcaires à Spatangues Formation.
Etymology. After the Latin “editus, a, um” (high, elevated) that refers to the high test morphology.
Diagnosis. As for the genus, by monotypy.
Description. Test length is 38.3 mm, test width 32.9 mm and test height 28 mm. In apical view, test outline pentagonal, with anterior margin rounded, greatest width posterior to centre and posterior margin pointed, almost rostrate ( Fig. 4A, C View FIGURE 4. A – E ). In lateral view ( Fig. 4B View FIGURE 4. A – E ), test highly inflated adapically, flat adorally. Test dome-shaped in frontal view, with very low ambitus, situated at the lowest third of test height ( Fig. 4D View FIGURE 4. A – E ). Oral side depressed.
Apical system anterior, distance between apical centre and front side 38% of test length. Apical system monobasal, covered with hydropores, with three genital pores, genital pore 3 is absent. Periproct inframarginal, oval, flush with test, tilted downwards (not visible in apical view). Peristome sub-central, the distance to the anterior side ca. 48% of test length, pentagonal in shape and depressed ( Fig. 4C View FIGURE 4. A – E ).
Petals flush with test, anterior petal and posterior petal pairs open adorally, ending gradually and tapering aborally; anterior petal pair bowed, closing adorally and tapering both adorally and aborally. About 20 pore pairs in a petal. Pore pairs located near the adoral boundary of ambulacral plates. Pores conjugate, the adradial pore of each pore-pair is very elongate, slit-like. There are no pore pairs in each ambulacral plate beyond petals (except in the phyllodes).
Phyllodes well-developed, bowed, broad, pore pairs conjugate, distinct inner series of about 10 pore pairs in each half ambulacrum and outer series of about seven pore pairs. Inner (peradial) or lowermost (adoral) pore of a pore pair the same size as the outer (adradial) or uppermost (aborally) pore respectively. No buccal pores are present. Bourrelets slightly developed.
The test is covered with small scrobicular tubercles that slightly increase in size adorally. No naked area in interambulacrum 5 on the oral side is present.
Remarks. In P. e d i t a gen. et sp. nov., test shape is quite atypical for neognathostomate echinoids in the Early Cretaceous. It seems to foreshadow the morphologies of ‘gitolampadid’ (e.g. Gitolampas lamberti Checchia- Rispoli, 1921) and ‘pygurid’ neognathostomates (e.g. Pyguropsis noetlingi de Loriol, 1899), which evolved at first in the Upper Cretaceous and show typical subpentagonal test outlines with rounded margins, planar oral surfaces (but sunken towards the peristome), domed to subconical upper surfaces and tapering posterior ends. However, P. edita gen. et sp. nov. differ from both ‘gitolampadid ‘ and ‘pygurid echinoids by the presence of three gonopores and absence of buccal pores. The presence of short and strongly bowed phyllodes with well-developed inner and outer series of pore-pairs, slightly developed bourrelets, no buccal pores and the absence of oral naked granular zone in interambulacrum 5 are diagnostic characters of ‘catopygids’ ( Kier 1962; Smith & Wright 2000), a group of cassiduloids with no representative recorded in the CSF so far. However, P. edita gen. et sp. nov. differ from ‘catopygids’ by its high rostrate test shape and monobasal apical system with 3 gonopores. According to Kier (1962), cassiduloids might have evolved monobasal apical systems not until the end of the Cretaceous. The discovery of P. e d i t a gen. et sp. nov. in the Early Hauterivian challenges this classic evolutionary scheme.
P. e d i t a gen. et sp. nov. is also very similar in test shape, apical system and ambulacral pores to some ‘pliolampadid’ echinoids (e.g. Pliolampas vassalli ( Wright, 1855) and Studeria elegans (Laube, 1869)) , which evolved in the Cenozoic ( Kier, 1962). In P. e di ta gen. et sp. nov., P. vassalli and S. elegans , the test is inflated with rounded margins, pointed posterior end and flat oral surface (but sunken towards the peristome). The apical system is monobasal with three gonopores (gonopore 3 absent), ambulacral pores are conjugate in petals, single beyond petals and bourrelets weakly developed. P. e d i t a gen. et sp. nov differ from the two other species by the absence of both buccal pores and single pored phyllodes, two derived features which appeared at first in the Upper Cretaceous ( Kier 1962).
P. e d i t a gen. et sp. nov is characterized by a unique composition of morphological characters, either derived (monobasal apical system with three gonopores) or ancestral (presence of double pored phyllodes and absence of buccal pores). As it does not fit into any other generic diagnosis, a new genus name was established.
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