Genre   Oligopygus de Loriol, 1887

Notes pour servir à l'étude des échinodermes, 1ère série, fascicule II, p.70

Espèce type  Oligopygus wetherbyi de Loriol, 1887, par désignation originale.

Notes pour servir à l'étude des échinodermes, 1ère série, fascicule II, p.72.

Extension stratigraphique (bibliographique, non vérifiée) : Eocène moyen et supérieur

Oligopygus haldemani (Conrad, 1850)

DISCOIDEA, Agass.

D. Haldemani.   Pl. 1, fig. 12.—Oval, convex-depressed ; ambulacral outlines wide, slightly converging towards the inferior extremities ; the inner pairs subrectilinear and slightly diverging from the apex to the inferior extremities; periphery rounded, and having an undulated outline; anus small, round ; mouth subcentral, transversely elliptical ; base between the anus and the posterior margin somewhat concave ; anteriorly slightly convex.
 

     Locality. Bainbridge, Baker county.

     Mr Couper's note, accompanying this species, informs us that it is from limestone dug out of a well seventy feet beneath the surface. The specimens are mineralized crusts, one of which is nearly perfect.

planche 1 (extrait)

http://collections.peabody.yale.edu/search/Record/YPM-IP-030205

spécimen YPM IP 030205

crédit photo YPM Jessica Utrup

Oligopygus haldemani (Conrad, 1850) - Eocène, Ocala limestone, Marion Cty, Floride, 27 mm

Oligopygus phelani Kier, 1967

OLIGOPYGUS PHELANI Kier, new species

Plate 22; text fig. 9

Oligopygus haldemani Fischer (not Conrad), 1951, Florida Geol. Surv. Bull. 34, pt. 2, p. 56.

     Material.—The following description is based on the holotype and 57 topotypic specimens.

     Shape.—Small, elongate, width 83 to 88 percent of length, lengthwidth ratio quite constant (text fig. 9a) ; in smaller specimens marginal outline oval, in large specimens subpentagonal, pointed anteriorly, blunted posteriorly with greatest width anterior; largest specimen 18.5 mm long, average specimen 10 to 13 mm long, smallest 6.0 mm long; greatest height commonly at apical system, in some specimens anterior; height quite variable varying from 42 to 60 percent of length (text fig. 9b) ; adapical surface slightly convex, sides smoothly curving, adoral surface lacking deep peristomal sulcus, only depressed immediately around peristome opening.

     Apical system.—Central to slightly posterior; monobasal (pl. 22, fig. 3), madreporite strongly inflated, several tubercles on madreporite ; ocular plates small ; four genital pores, anterior pair closer together than posterior, pores large in some specimens small in others ; not visible in any specimens smaller than 8 mm long.

     Ambulacra.—Petals well developed, open in some specimens, straight, slightly closing in others; interporiferous zone widest in petal III where almost twice as wide as single poriferous zone; in other petals interporiferous zone slightly wider than poriferous zone; petal III longest with from 4 to 9 more pore-pairs in single poriferous zone than petals II or IV, 4 to 7 more than petals V or I; in largest specimen, 18.5 mm long, 23 pore-pairs in single poriferous zone of petal III, in smallest specimen, 6.0 mm long, 11 pore-pairs; outer pore of pair distal to inner; pores strongly conjugate (pl. 22, fig. 3) , in sutures between plates.

     Beyond petals, ambulacral plates single pored; at extremity of petal, pores very numerous in many included and demiplates; at ambitus pores most crowded in double series in each half-ambulacrum with continuous column of demiplates separating primary plates from adradial suture; a few included plates inserted between primaries and demiplates ; included and demiplates near adradial border, plates thin not extending through test ; nearing peristome primary plates extend to adradial suture, no included plates, one demiplate for each primary ; buccal pores difficult to see.

     Interambulacra.—Two columns in each area except at peristome where column terminating in single plate.

     Peristome.—Slightly anterior, central, or slightly posterior, opening slightly wider than high, in specimen 17.5 mm long, opening 2.18 mm wide, 1.94 mm high, opening (pi. 22, fig. 5) curved anteriorly, slightly pointed posteriorly; not in deep sulcus, test only depressed in area immediately around opening.

     Periproct.—Small, 1.4 mm wide in specimen 17.5 mm long, slightly wider than high; located between 54 and 73 percent of the distance from center of peristome to posterior margin.

     Tuberculation.—Test covered with small, irregularly arranged tubercles; scrobicules deep with vertical side; boss large, two-thirds diameter of scrobicule, extending upward as high as surrounding surface of test ; crenulated ; mamelon small, extending in height above surface of test, perforated ; crenulations and mamelon present only in well-preserved specimens ; small secondary tubercles scattered over area between tubercles.

     Location of type specimen.—Holotype USNM 649845 ; figured specimen USNM 649846.

     Occurrence.—Late Eocene, Inglis Formation, Florida : NW 1/4 NW 1/4 Sec. 30, & 17S, R20E, Citrus Co.; S. bank Withlacoochee River about 50 ft. SE of Hwy. 200 bridge at Stokes Ferry. Florida Geol. Survey loc. 1-5377, quarry in Citrus County south of Withlacoochee River one mile west of bridge at Inglis, Levy County; spoil banks along first 4 miles of Trans-Florida Canal near Inglis (loc. of holotype).

     Remarks.—This species is named for Thomas F. Phelan of the U.S. National Museum who first recognized that the specimens of Oligopygus from the Inglis Formation were different in appearance from those of the Crystal River Formation.

     Comparison with other species.—Specimens of this species have previously been referred to Oligopygus haldemani which occurs in the higher Crystal River Formation. Although O. phelani is very similar to O. haldemani in shape, having the same length to width and height ratios, and similar petals, it is easily distinguished from it by its lack of a deep peristomal trough and its more anteriorly situated periproct. In O. haldemani the peristome is in a deep  transverse trough, whereas in O. phelani the test is only depressed in the area immediately around the opening. In O. phelani the periproct is located between 54 and 73 percent the distance from the center of the peristome to the posterior margin, whereas in O. haldemani it is located at 76 to 84 percent of this distance. Furthermore, O. phelani is a smaller species, the largest specimen being 18.5 mm long, whereas in O. haldemani the largest specimen is 37 mm long.

     O. phelani likewise differs from O. wetherbyi in lacking a deep peristomal trough. Its periproct is more posterior than in O. wetherbyi and its test is smaller.

     O. rotundus differs from O. phelani in having a broad and steep peristomal trough.

planche 22 (extrait)

http://n2t.net/ark:/65665/3f2f67c0d-c98f-4623-a643-9b3313b3a08d

spécimen USNM MO 649845

crédit photo Suzanne McIntire

Kier, p. 81 pl. 22

Oligopygus phelani Kier, 1967 - Eocène supérieur, Crystal River Form., Ocala Group, Gainesville, Floride, U.S.A., 14 mm

Oligopygus putnami Israelski,1933

Oligopygus putnarni, Israelsky, new species

Plate 18, figures 1, 2, 3, 4

     Test tumid, thick walled; outline from above ovoid; ambitus rounded; madreporic system posterior to the center; petals reach about one-half the distance to the ambitus, tending to close distally, interpo­riferous areas strongly raised; greatest width of petals about one-third length; anterior unpaired petal slightly longer than paired petals, paired petals subequal; viewed from the side the outline is strongly arched above, higher anteriorly than posteriorly, and concave below; the peristome lies in a deep transversely elongate groove slightly behind the center; periproct about two-thirds the distance from peristomal groove to ambitus; surface apparently ornamented with stnall scrobiculate tubercles.

     Syntypes: Nos. 5210, 5211, Mus. Calif. Acad. Sci., collected by Lawrence G. Putnam., 12 kilometers northeast of Abasola, Tamaulipas, Mexico; upper Eocene. Topotypes: 5214 and 5215, C. A. S. type collection. Plasto-Syntypes: Nos. 422, 423, San Diego Society of Natural History type collection. Idiotypes: 424, 425, S. D. S. N. H. type collection.  

     The new species appears to be more closely related to Oligopygus haldermani (Conrad) 1 than to any other thus far described. It may be readily distinguished from that foret by its more anterior periproct. The posterior position of the madreporic system appears to separate it from other species of the genus.

     The species may be the one found by Wise and Cavins in this same district, but not named by them.

planche 18 (extrait)

Oligopygus putnami Israelski,1933 - Eocène supérieur, chiapas, Mexique, 31 mm

Oligopygus putnami Israelski,1933 - Eocène supérieur, chiapas, Mexique, 26 mm

Oligopygus wetherbyi de Loriol,1887

     Material.—Description based on 140 specimens from the Crystal River Formation near Ocala, Fla., the lectotype, and paralectotype.

     Shape.—Test elongate, with greatest width posterior to center, greatest height at apical system, adapical surface slightly convex, sides smoothly curving, adoral surface deeply depressed in wide sulcus at peristome ; shape of test only slightly variable, with lengthwidth ratio quite constant, width 80-86 percent of length (text fig. 24) although length-height more variable, height 40-50 percent of length (text fig. 30b) ; large specimens subpentagonal in marginal outline, average length 36 mm, largest 54.

     Apical system.—Central to slightly anterior; monobasal, central area strongly inflated (pi. 1, figs. 3, 4), two to four tubercles on madreporite; ocular plates (pi. 1, fig. 4; text fig. 25d) small, inflated on well-preserved specimens ; four genital pores located in suture between madreporite and interambulacra ; large genital pores in some specimens, very small in others, probably sexually dimorphic ; anterior pair closer together than posterior; present on specimen 18 mm long.

     Ambulacra.—Petals well developed, straight, open, with greatest width at extremities of petals, petal III longest, petals II, IV shortest; interporiferous zones expanding distally, slightly constricted at extremities of petals, approximately twice as wide as poriferous zone at extremity of petal; pores strongly conjugate (pi. 2), oblique, with outer pore of pair more distal to inner; pores in sutures between plates, converging somewhat interiorly (text fig. 2), ambulacral plates of petals very thin; adradial suture surface not vertical resulting in ambulacra being narrower at interior of test than at exterior; in specimen 54 mm long 52 pore-pairs in single poriferous zone petal III, 47 in petal II, 48 in petal V ; petal III with from 4 to 12 (average 6) more pore-pairs than petal II, petal II with from 1 to 7 (average 4) fewer pore-pairs than petal V (text figs. 38, 39).

     Beyond petals ambulacral plates single pored; at extremity of petal (text figs. 25a, 26a) pores very numerous in many demi- and included plates; beyond this area and continuing most of length of ambulacrum each large primary has 3^1/2 to 6 small demi- or included (text figs. 26b, c) plates along its adradial border; small plates very thin, on slightly weathered specimens some missing ; all absent on moderately weathered specimen ; in ambulacra II, III, and IV beyond petal approximately 66 primary plates, in ambulacra V and I, 82 large plates; near peristome pores less crowded (text fig. 25c) ; 115 pores in single poriferous zone of petal III ; ambulacra terminate at peristome with two large plates arranged in normal manner with larger plate in right zone of ambulacrum III, adapical in ambulacrum IV, adoral in all others; buccal pores visible on some specimens, difficult to see on most.

     Interambuhcra.—Two columns of plates in each area except at peristome where column terminating in single plate; approximately 34 plates in interambulacra 4 or 1, 39 in 5, 36 in 2 or 3 (in specimen 37 mm long).

     Peristome.—Central, wider than high (pl. 4, fig. 1), curved anteriorly, pointed posteriorly ; located in deep, transverse depression (pl. 4, fig. 2) considerably wider than high, 40-50 percent as wide as test, anterior of depression more steeply sloping than posterior.

      Periproct.—Small, 2.1 mm wide in specimen 45 mm long; circular, located midway between peristome and posterior margin in large specimens, slightly nearer the posterior margin in smaller.

     Tuberculation.—Test covered with small, irregularly arranged tubercles; scrobicules deep, with vertical sides; boss large, almost two-thirds diameter of scrobicule, extending upward as high as surrounding surface of test ; crenulated ; mamelon small, extending in height above surface of test, perforated ; crenulations and mamelon present only in well-preserved specimens ; small secondary tubercles scattered over area between tubercles.

     Interior.—Test with thick plates (text fig. 11a), in specimen 47 mm long adapical ambulacral plates at midlength of petal III 3.6 mm thick, at adoral interambulacrum 5 midway between posterior margin and peristome 3.9 mm thick ; on adoral surface ambulacra much thinner than interambulacra producing deep grooves in ambulacra in interior.

     Location of type specimens.—The lectotype, herein designated, is the specimen figured by de Loriol (1888) on his plate 17, fig. 7, and herein on plate 13, figs. 1, 2. The paralectotype, figured on de Loriol's plate 17, fig. 18, is herein figured on plate 13, figs. 3, 4. These specimens are in de Loriol Collection at the Museum d'Histoire Naturelle in Geneva, Switzerland. Specimens figured by Cook and Kier (herein) are in the U.S. National Museum : USNM nos. 562271, 562272, 164660 (holotype of 0. floridanus), 137881, 649832, 649833, 649838, 649841, 649842, 649843, 649849, 649851, 649853.

     Occurrence.—Late Eocene, Crystal River Formation, and Williston Formation, Florida. For an extensive list of localities see Cooke (1959, p. 28).

     Comparison with other species.— O. wetherbyi is found commonly with O. haldemani and on first impression they look quite similar. In O. wetherbyi, however, the periproct is always much nearer the peristome than in O. haldemani. I measured the distance from the periproct to the posterior margin in all the specimens from one locality and plotted them on a scatter diagram (text fig. 27). The points fall into two widely separated patterns with no overlap.

     Usually the periproct opening in O. wetherbyi is more circular, there are more pore-pairs in petals III and V, I (text figs. 38, 39), the test is slightly narrower (text fig. 24), and the greatest width posterior (particularly in larger specimens). Also the interambulacral plates are more commonly tumid. These differences, however, are slight and not consistent. O. wetherbyi reaches a larger size than O. haldemani: one of the larger O. wetherbyi is 54 mm long (average 36 mm), the largest O. haldemani 37 mm (average 21 mm).

     Remarks.—I agree with Cooke (1959, p. 28) in considering O. floridanus Twitchell as a junior subjective synonym of O. wetherbyi. Twitchell's holotype differs from specimens of O. wetherbyi that occur with it only in appearing to have narrower poriferous zones. This appearance is due to the fact that the holotype is a badly weathered specimen.

     Palmer (in Sanchez Roig, 1949, p. 166) erected a variety Oligopygus floridanus, var. laevis for some specimens from the late Eocene (middle or late occurring to Brodermann, 1949, in Sanchez Roig, p. 325) of Cuba. Unfortunately he did not figure his specimens and from his description I cannot be sure that these specimens should be referred to O. wetherbyi.

planches 1,4,5,8,10,13,14,16(extraits)

fig.1-2 ►		fig.3-4 ◄

Oligopygus wetherbyi de Loriol,1887 - Eocène supérieur, Sewanee Cty, Floride, U.S.A., 43 mm

Oligopygus wetherbyi de Loriol,1887 - Eocène supérieur, Ocala limestone, Yankee Town, Floride, U.S.A., 14 mm