Levisulculus extrarius ( Öpik, 1937 )

Schallreuter, Roger E. L. & Hinz-Schallreuter, Ingelore C. U., 2010, Sexual dimorphism and pore systems in Ordovician ostracodes, Acta Palaeontologica Polonica 55 (4), pp. 741-760 : 750

Levisulculus extrarius ( Öpik, 1937)

Figs. 3A–D, 7C.

1937 Primitia extraria n. sp., Primitia? extraria n. sp.; Öpik 1937: 69, 82, 133 (5, 18, 69), pl. 10: 19.

1940 Primitia troedssoni n. sp.; Thorslund 1940: 163–164, 186, pl. 1: 13–15.

1940 Primitia granulosa n. sp.; Thorslund 1940: 163–164, 186, pl. 1: 16.

1957 Levisulculus extraria (Öpik) , L. extraria Öpik ; Jaanusson 1957: 180, 321, 325, 326.

1957 Levisulculus troedssoni (Thorslund, 1940) ; Jaanusson 1957: 321, 323, 324–325, table 24; text−fig. 32A, pl. 8: 16–18.

1957 Levisulculus granulosus (Thorslund, 1940) , L. granulosa ; Jaanusson 1957: 321, 326, text−fig. 32B, pl. 8: 19.

1959 Levisulculus extraria (Öpik) ; Sarv 1959: 41–42, table 2 (p. 186), pl. 7: 1.

1975 Levisulculus extrarius ( Öpik,1937) [after Sarv possibly synonymous witht L. troedssoni and L. granulosa ]; Schallreuter 1975: 157, 158.

1979 Levisulculus extraria (Oepik, 1937) = Primitia troedssoni Thorslund, 1940 = Primitia granulosa Thorslund, 1940 , L. troedssoni , L. granulosus , L. treedssoni ; Ivanova 1979: 102–103, 188, pl. 7: 5.

1992 Levisulculus extraria ( Öpik, 1937) =? Levisulculus troedssoni (Thorslund, 1940) + L. granulosus (Thorslund, 1940) ; Sidaravičienė 1992: 140, 143.

Holotype: Tecnomorphic right valve, TUG 1120−1 ( Öpik 1937: pl. 10:

19; Sarv 1959: pl. 7: 1).

Type horizon: Kohtla−Järve, Estonia.

Type locality: Kukruse formation (C2 α), lower Upper Ordovician.

Diagnosis (emended).—Length at least up to 0.98 mm (holotype 0.88 mm). Shape mostly moderately long to rather long, domicilium mostly long to very long. Very small preadductorial node. Posteriorly directed velar spine at the border between the posteroventral and posterocentral regions. Lateral surface pustulate.

Dimensions and proportions.—See Table 4.

Disscussion.— Sarv (1959: 41), Ivanova (1979: 102–103) and Sidaravičienė (1992: 140) considered Levisulculus extrarius , Levisulculus granulosus , and Levisulculus troedssoni to be possible or definite synonyms. For the present, we agree with their assessment because the holotypes of these nominal species—all right valves—are not only very similar to each other ( Fig. 2B–D ) but also come from about the same stratigraphical level (C2 α or “lowermost Ludibundus limestone”, respectively).

Levisulculus extrarius is very similar to L. obliquus . Distinctly different, however, is the position of the velar spine. L. extrarius is slightly smaller and a little more elongate than L. obliquus . The younger Levisulculus levis is larger (1.22–1.48 mm) and the antrum appers to be a little longer posteriorly ( Sidaravičienė 1992: pl. 36: 4, 7; Meidla 1996: pl. 2: 11). A velar spine is unknown in L. levis as is the small preadductorial node.

Stratigraphic and geographic range.— Estonia: Kukruse formation (C2 α), lower Upper Ordovician. Tvären: erratic boul− der of lower Chasmops limestone (lowermost Ludibundus limestone).

Figures

Fig. 2. Oepikellid ostracods from Palaeozoic erratic boulders. A. Holotype of the type species of the oepikellid ostracod Levisulculus, Levisulculus lineatus Jaanusson, 1957 (UM T89), female left valve, length (L) 0.89 mm. B. Holotype of Primitia extraria Öpik, 1937 (TUG 1120−1; Kukruse Stage, Estonia), tecnomorphic right valve, L 0.88 mm. C. Holotype of Primitia troedssoni Thorslund, 1940 (UM T10), tecnomorphic right valve, L 0.79 mm. D. Holotype of Primitia granulosa Thorslund, 1940 (UM T11), tecnomorphic right valve, L 0.86 mm (Jaanusson 1957: pl. 8: 12, Öpik 1937: pl. 10: 19, Thorslund 1940: pl. 1: 16, 13). E–H. Primitia elongata obliqua Steusloff, 1895: type series, all tecnomorphic valves embedded in rock. Geschiebe (glacial erratic boulder) from Neubrandenburg. E. Lectotype GG 114−27, left valve, L 1.16 mm (without velum). F. GG 114−26, right valve, L 1.07 mm. G. GG 114−28, right valve, L 0.99 mm (without velum). H. GG 114−29, right valve, L 0.82 mm. I. Primitia canaliculata Steusloff, 1895, holotype GG 114−25, steinkern of a juvenile right valve embedded in rock, L 0.70 mm, same erratic boulder.