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Muderongia simplex

Muderongia simplex Alberti, 1961; Emendations: Monteil, 1991b, p.475; Poulsen, 1996, p.57; Riding et al., 2001, p.29.

Taxonomic junior synonym: Muderongia longicorna, according to Poulsen (1996, p.57) — however, Monteil (1996, p.42) retained Muderongia longicorna; Muderongia perforata, according to Jain and Khowaja-Ateequzzaman (1984, p.39) — however, Lentin and Williams (1989, p.252) retained Muderongia perforata;
Taxonomic junior synonym: Muderongia tomaszowensis, according to Jain and Khowaja-Ateequzzaman (1984, p.39) and Poulsen (1996, p.58) — however, Riding et al. (2001, p.31) retained Muderongia tomaszowensis;
Taxonomic junior synonym: Senoniasphaera tabulata, according to Riding et al. (2001)

Holotype: Alberti, 1961, pl.2, fig.4; lost according to Riding et al. (2001,p.30).
Neotype: Davey, 1979c, pl.2, fig.5, as Muderongia sp. A; Monteil, 1991b, pl.1, figs.3a–c, as Senoniasphaera tabulata; Riding et al., 2001, pl.1, figs.4–5; designated by Riding et al. (2001, p.30).
Locus typicus: Dabendorf Well near Berlin, Germany
Stratum typicum: Valanginian-Early Barremian
Translation Alberti, 1961: LPP

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G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP VIEWER CD-ROM 99.5.

Muderongia simplex Alberti, 1961, emend. Monteil, 1991b, emend. Poulsen, 1996. According to Poulsen (1996), Muderongia simplex has 4-5 prominent horns, one apical, two lateral and essentially equatorial, and two antapical. Horns conical with rounded, closed ends. Cornucavate or delphicavate to nearly circumcavate. Endocyst round, rhombic, or extended into horns. Endophragm psilate to granulate. Periphragm thin, psilate, scabrate or perforate. Apical archeopyle type (4A). Paratabulation indicated mainly by archeopyle, sometimes by low ridges, formula ?pr, 4', 6", 6c, 6"’, 1p, 1"”. Parasulcus narrow and sinuous. Poulsen includes Muderongia sp. A of Davey in synonymy. Size: holotype, length 151 µm, width 121 µm.
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Original description: Alberti 1961, p. 12
Diagnosis: Shell flattened, the outline about rhombic. Apical horn, two mostly
unequally long antapical horns and two strongly protruding and distally indented lateral horns. The latter are generally unequally long, standing almost perpendicular to the longitudinal axis. Apical and antapical horns distally slightly blunt. A flat transversal furrow is now and then present, a longitudinal furrow is rare. A weak tabulation of the shell is sometimes indicated. Edges smooth, without
sines or thorns. Inner body always present.
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Emended diagnosis: Monteil, 1991, p. 475
Cysts proximate, compressed dorsoventrally, two-layered, cornucavate. Pericyst ceratioid, asymmetrical, with 5 prominent horns: 1 apical (axial, type AP l); 2 subequal lateral (axial, type L 1), indented; 2 inequal antapical (joined, type ATP ll). Left antapical horn longer (up to four times) than the right one. Horns normal with distal extremities closed and rounded; proximal extremities narrow. Endocyst typically cruciform pentangular, stretching out up to the middle part of the five horns. Periphragm thin, psilate to scabrate. Endophragm thin, psilate to granulate. Archeopyle apical, type (4A), with angular margin. Parasulcal notch marked. Operculum free. Paratabulation indicated by archeopyle, by low parasutural ridges or septa. Formula: ?pr, 4', 0a, 6", 6c, 6''', 1p, 1''''. Pericingulum marked by indentation of lateral horns and by parallel transverse structures. Perisulcus indicated by parasulcal notch offset. Perisulcal area not observed.
Dimensions of the holotype (with operculum): 151 Ám x 121 Ám (overall L x 1).

Affinities:
Alberti, 1961, p. 12: M simplex differs from M. mcwhaei in the development of the lateral horns as well as the, mostly stronger, second antapical horn.
Monteil, 1991, p. 475: Muderongia simplex differs from Senoniasphaera tabulata Backhouse & Helby in Helby 1987 in having two lateral horns rather than an equatorial paracingular protrusion.
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Poulsen 1996, p. 57-58, Pl. 23, Figs. 2, 3, 5

Muderongia simplex Alberti, 1961, p. 12, pl. 2, figs. 1-2, 4-6
Muderongia tomaszowensis Alberti, 1961, p. 12-13, figs. 12-13
Muderongia simplex Duxbury, 1977, p. 55, pl. 14, fig. 9
Muderongia simplex sensu stricto Raynaud, 1978, p. 398, text-fig. 5, no. 43
Muderongia sp. A Davey, 1979, p. 64, pl. 2, figs. 4-5
Muderongia simplex ssp. microperforata Davey, 1982, p. 30, pl. 9, figs. 4-6
pars Muderongia longicorna Monteil, 1991b, p. 473, pl. 2, fig. 1-2 only
(holotype pl.2, fig. 1), non pl. 2, fig. 3.

Emended diagnosis. A species of Muderongia with 4-5 usually prominent horns, one apical, two lateral and essentially equatorial, and two antapical. Horns conical with rounded, closed ends. Cornucavate or delphicavate to nearly circumcavate. Endocyst round, rhombic or extended into horns. Endophragm psilate to granulate. Periphragm thin, psilate, scabrate, or perforate. Apical archeopyle type (4A). Paratabulation indicated mainly by archeopyle, sometimes by low ridges; formula ?pr, 4' 6", 6c, 6"', 1p, 1"". Parasulcus narrow and sinuous.
Emended description. Shape: Cyst proximate, ceratioid, compressed dorsoventrally. Pericyst with 4-5 usually prominent horns, one apical, two lateral and essentially equatorial, and two antapical; the right antapical horn is smaller than the left and may be only weakly developed. Horns conical with rounded, closed ends. Endocyst round, rhombic or extended into horns. Wall relationship: Two wall layers, cornucavate or delphicavate to nearly circumcavate. Wall features: Periphragm thin, psilate, scabrate, or perforate. Endophragm psilate to granulate. Archeopyle: apical, type (4A), with the margin showing a distinct offset of the parasulcal notch; operculum free. Paratabulation: Indicated mainly by archeopyle, sometimes by low ridges; formula ?pr, 4' 6", 6c, 6"', 1p, 1"". Paracingulum: Marked by low ridges and indentation of lateral horns. Parasulcus: Marked by parasulcal notch offset, and a narrow and sinuous depression. Size: intermediate to large (78-140 Ám).
Dimensions. Length about 78-176 Ám (including operculum), length 42-124 Ám (apex lost), width 51-118 Ám, endocyst length 30-70 Ám (apex lost), endocyst width 30-71 Ám, length of horns, apical horn 14-47 Ám, lateral horns 10-37 Ám each, and left antapical horn 18-40 Ám, right antapical horn 8-22 Ám.
Remarks. The emendation of M. simplex by Monteil (199lb) is extended to include forms which have a subspherical rather than angular endocyst. This species has four or five prominent horns. When only four prominent horns are present, the right antapical horn is reduced. The variability of this species ranges from cornucavate forms in which the endocyst extends into the horns to cornucavate forms with 'round' endocyst to delphicavate or almost circumcavate forms.
The description is emended to include Muderongia sp. A of Davey, 1979, which already has been regarded as belonging to M. simplex (Barron, 1989; Riding and Thomas, 1988). The distinction between Muderongia sp. A of Davey 1979 and Muderongia simplex was discussed by Barron (1989) and Riding and Thomas (1988), referring to the original description of M. simplex, which states that the endocyst lies close to the pericyst, often stretched out somewhat into the horns. Barron (1989) felt that Muderongia sp. A is equivalent to M. simplex, and that the form referred to M. simplex by Duxbury (1977) possibly is a separate species. Muderongia simplex of Duxbury (1977) has been regarded as M. simplex Alberti 1961 by many palynologists, e.g. Davey (1979, 1982). Here, M. tomaszowensis is regarded as a taxonomic junior synonym of M. simplex.
Raynaud's (1978, p. 398, text-fig. 5, no. 31) Muderongia cf. simplex forma A and Raynaud's (1978, p. 398, text-fig. 5, no. 43) Muderongia simplex sensu stricto are both regarded as M. simplex by me.
Monteil (199 l b) described his new species Muderongia longicorna as having an oval to rhomboidal endocyst, often with eccentric antapex extending in the left antapical horn, and differentiated it from M. simplex, which he describes as having a cruciform pentangular endocyst, stretching up to the middle part of the five horns. He divided Muderongia sp. A in Davey (1982, pl. 9, figs. 1-3) into both M. Iongicorna (Davey's fig. 2-3) and M. simplex (Davey's fig. 1). Thus Monteil divided two nearly identical cysts from the same sample into two different species. In my opinion, the two figured specimens by Davey (1982) belong to the same species. Following Barron (1989) and Riding and Thomas (1988), Muderongia sp. A of Davey 1979 should be regarded as conspecific with M. simplex Alberti 1961.
Lentin and Williams (1989) did not agree with Jain and Khowaja-Ateequzzaman (1984) that M. tomaszowensis is a taxonomic junior synonym of M. simplex. Lentin and Williams (1993) regarded Phoberocysta neocomica as a taxonomic senior synonym of Muderongia tomaszowensis. In my opinion, P. neocomica and M. tomaszowensis are two separate species, belonging to two different genera.
Occurrences. Muderongia simplex has generally been regarded as a Cretaceous species, but with the inclusion of Muderongia sp. A of Davey 1979 in M. simplex, the first occurrence of M. simplex is from the Rotunda Zone (Portlandian) of Britain (Riding and Thomas, 1988). The first uncertain occurrence in the North Sea area is in the Elegans Zone (beginning of the Volgian) and its first consistent occurrence is from the Hudlestoni Zone (Raynaud, 1978). Woollam and Riding (1983) recorded the Hudlestoni Zone as the first uncertain appearance and the first certain occurrence in the Albani Zone.
The holotypes of M. simplex and M. tomaszowensis are from the Valanginian of the Dabendorf borehole near Berlin. The range was regarded as Valanginian to Hauterivian in the protologue (Alberti, 1961). The holotype of M. Iongicorna is from the Berriasian stratotype section, Ardeche, France, Early Berriasian (Boissieri Zone, Paramimounum Subzone).
Duxbury (1977) observed the range of M. simplex as Berriasian to Barremian.
In Denmark the range is recorded as Glossodinium dimorphum Zone, Subzone d to Discorsia nanna Zone, (mid-Middle Volgian to Early Hauterivian) (Davey, 1982; this study). Note that it is recorded in the ammonite dated samples of Aars-l, sidetrack 3 of the Albani Zone. The forms recorded from Denmark in this study are all of the delphicavate type with an endocyst extending into the horns. In the Danish North Sea sector, sediments of similar age include both circumcavate and delphicavate forms of M. simplex. Several specimens of M. simplex occur also in the Polish material from the Scythicus Zone (Middle Volgian). The forms recorded from Poland are delphicavate to nearly circumcavate with a 'round' endocyst. Heilmann-Clausen (1987) recorded a range of Muderongia simplex in the Danish North Sea as latest Ryazanian to Early Aptian.

Accepted subspecies.

Muderongia simplex subsp. simplex (Autonym) - Pl. 23, Fig. 2-3, 5
Muderongia simplex Alberti, 1961, p. 12, pl. 2, figs. 1-2, 4-6.
Muderongia tomaszowensis Alberti, 1961, p. 12-13, figs. 12-13.
Muderongia simplex Duxbury, 1977, p. 55, pl. 14, fig. 9.
Muderongia simplex sensu stricto of Raynaud, 1978, p. 398, text-fig. 5, no. 43.
Muderongia sp. A of Davey, 1979, p. 64, pl. 2, figs. 4-5.
pars Muderongia longicorna Monteil, 1991b, p. 473, pl. 2, fig. 1-2 only, non pl. 2, fig. 3.
Senoniasphaera tabulata Backhouse and Helby 1987, in Monteil l991b, pl. 1, figs. 3 a-c.

Muderongia simplex subsp. microperforata Davey 1982
Muderongia simplex subsp. microperforata Davey, 1982, p. 30, pl. 9, figs. 4-6.
Muderongia microperforata (Davey, 1982) Monteil, 1991b, p. 474, pl. 2, fig. 10.
Remarks. This form was regarded as a separate species by Monteil (1991b). Since a wide variety of forms are included within M. simplex, this form belongs this species as proposed by Davey (1982).
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