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Muderongia crucis
Muderongia crucis Neale and Sarjeant, 1962; emend. Monteil, 1991
Tax. jr. synonym of Muderongia tetracantha (Gocht, 1957) Alberti, 1961, according to Morgan, 1980. Jansonius, 1982, and Monteil, 1991, retained Muderongia crucis as a separate species.
Holotype: Neale and Sarjeant, 1962, pl.20, fig.6, text-fig.6; Monteil, 1991, pl.5, fig.6
Locus typicus: Heslerton, England
Stratum typicum: Late Hauterivian
Original diagnosis: Neale and Sarjeant, 1962, p. 449
A species of Muderongia having an oval to ellipsoidal shell from which arises four strong horns. All four horns have a length approximately equivalent to the long diameter of the shell. The apical and antapical horns taper progressively from base to tip and correspond to the long axis of the shell. The two lateral horns arise at right angles to the long axis, in the median plane, and are at first only slightly tapering; at about one-third length they are swept backward and become abruptly thinner, tapering thenceforth to their tips. The shell is not tabulate, nor does it show trace of a transverse furrow; the lateral horns are not notched.
Original description: Neale and Sarjeant, 1962, p. 449-450
Shell yellowish-brown, perforate; the perforations are variable in size and distribution, but tend to be most concentrated in the horns. The majority of specimens seen consisted of shells lacking an apex or of detached apices; the type, the only relatively complete specimen encountered lacks the tips of the antapical and a lateral horn (see Text-fig. 6).
Dimensions: Type; overall length 252 Ám, overall breadth (maximum span) 127.5 Ám, shell length 101.5 Ám, breadth 43.5 Ám. Estimated range of overall lengths of complete specimens 250-325 Ám.
Emended diagnosis: Monteil, 1991, p. 473
Cysts proximate to proximochorate, compressed dorsoventrally, two-layered, cornucavate. Pericyst ceratioid, symmetrical, with 4 prominent tapered horns:
1 apical (axial, type AP l); 2 subequal lateral (bent, type L ll), not indented; 1 antapical (axial, type ATP 1). Left lateral horn may be slightly more reduced than the right one. Postcingular extension long. Distal extremities closed and pointed;
proximal extremities narrow. Endocyst oval to rhombic, sometimes with a protrusion at the bases of the horns. Periphragm thin, psilate to scabrate, sometimes finely perforated in the distal two-thirds of the horns; small perforations not organized or arranged in few rows; periphragm may be ornamented by processes (stages I to IV). Endophragm thin, psilate to granulate. Archeopyle apical, type (4A), with angular margin. Parasulcal notch marked. Operculum free. Paratabulation only indicated by archeopyle, and more or less clearly expressed by distribution and type of processes (stages I to IV), when those are present. Formula: ?pr, 4", 0a, 6", 6c, 6""", 1p, 1"""". Pericingulum suggested by the lateral horns Perisulcus marked by parasulcal notch offset. Perisulcal area not observed.
Dimensions of the holotype (with operculum): 252 Ám x 127,5 Ám (overall L x I).
Affinities:
Neale and Sarjeant, 1962, p. 450: Muderongia crucis differs, in the length and form
of its horns, from all described species. Muderongia tetracantha (Gocht 1957) and M. mcwhaei Cookson and Eisenack 1957 both have backwardly swept lateral horns; however, in both species these are clearly notched. In addition, the horns of M. tetracantha are very slender, whilst M. mcwhaei shows clear traces of tabulation and has irregular outgrowths at the base of the antapical horn.
Monteil, 1991, p. 473: Muderongia crucis differs from M. staurota in having a narrower axial part of the lateral horns, a longer postcingular extension and a narrow antapical pericoel.
Tax. jr. synonym of Muderongia tetracantha (Gocht, 1957) Alberti, 1961, according to Morgan, 1980. Jansonius, 1982, and Monteil, 1991, retained Muderongia crucis as a separate species.
Holotype: Neale and Sarjeant, 1962, pl.20, fig.6, text-fig.6; Monteil, 1991, pl.5, fig.6
Locus typicus: Heslerton, England
Stratum typicum: Late Hauterivian
Original diagnosis: Neale and Sarjeant, 1962, p. 449
A species of Muderongia having an oval to ellipsoidal shell from which arises four strong horns. All four horns have a length approximately equivalent to the long diameter of the shell. The apical and antapical horns taper progressively from base to tip and correspond to the long axis of the shell. The two lateral horns arise at right angles to the long axis, in the median plane, and are at first only slightly tapering; at about one-third length they are swept backward and become abruptly thinner, tapering thenceforth to their tips. The shell is not tabulate, nor does it show trace of a transverse furrow; the lateral horns are not notched.
Original description: Neale and Sarjeant, 1962, p. 449-450
Shell yellowish-brown, perforate; the perforations are variable in size and distribution, but tend to be most concentrated in the horns. The majority of specimens seen consisted of shells lacking an apex or of detached apices; the type, the only relatively complete specimen encountered lacks the tips of the antapical and a lateral horn (see Text-fig. 6).
Dimensions: Type; overall length 252 Ám, overall breadth (maximum span) 127.5 Ám, shell length 101.5 Ám, breadth 43.5 Ám. Estimated range of overall lengths of complete specimens 250-325 Ám.
Emended diagnosis: Monteil, 1991, p. 473
Cysts proximate to proximochorate, compressed dorsoventrally, two-layered, cornucavate. Pericyst ceratioid, symmetrical, with 4 prominent tapered horns:
1 apical (axial, type AP l); 2 subequal lateral (bent, type L ll), not indented; 1 antapical (axial, type ATP 1). Left lateral horn may be slightly more reduced than the right one. Postcingular extension long. Distal extremities closed and pointed;
proximal extremities narrow. Endocyst oval to rhombic, sometimes with a protrusion at the bases of the horns. Periphragm thin, psilate to scabrate, sometimes finely perforated in the distal two-thirds of the horns; small perforations not organized or arranged in few rows; periphragm may be ornamented by processes (stages I to IV). Endophragm thin, psilate to granulate. Archeopyle apical, type (4A), with angular margin. Parasulcal notch marked. Operculum free. Paratabulation only indicated by archeopyle, and more or less clearly expressed by distribution and type of processes (stages I to IV), when those are present. Formula: ?pr, 4", 0a, 6", 6c, 6""", 1p, 1"""". Pericingulum suggested by the lateral horns Perisulcus marked by parasulcal notch offset. Perisulcal area not observed.
Dimensions of the holotype (with operculum): 252 Ám x 127,5 Ám (overall L x I).
Affinities:
Neale and Sarjeant, 1962, p. 450: Muderongia crucis differs, in the length and form
of its horns, from all described species. Muderongia tetracantha (Gocht 1957) and M. mcwhaei Cookson and Eisenack 1957 both have backwardly swept lateral horns; however, in both species these are clearly notched. In addition, the horns of M. tetracantha are very slender, whilst M. mcwhaei shows clear traces of tabulation and has irregular outgrowths at the base of the antapical horn.
Monteil, 1991, p. 473: Muderongia crucis differs from M. staurota in having a narrower axial part of the lateral horns, a longer postcingular extension and a narrow antapical pericoel.