Paromalomena polonica ( Temple, 1965 )
publication ID |
https://doi.org/ 10.4202/app.2013.0010 |
persistent identifier |
https://treatment.plazi.org/id/81298792-FFE4-A24D-FCE0-F9D6FF40D548 |
treatment provided by |
Felipe |
scientific name |
Paromalomena polonica ( Temple, 1965 ) |
status |
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Paromalomena polonica ( Temple, 1965) View in CoL
Fig. 4A, B, F–H View Fig .
1965 Platymena? polonica View in CoL n. sp.; Temple 1965: 407–410, pl. 15: 1–4; pl. 16: 1–5.
2008 Paromalomena polonica (Temple) View in CoL ; Cocks 2008: 63 (see synonyms therein).
Material.— Eight specimens embedded in rock. Porkuni Regional Stage , Kuldiga Formation , Hirnantian ( Upper Ordovician ); Latvia, Estonia. Drill core and depth (in meters) of sample with brachiopod. Depth of fragmentary specimens is marked by “?”. Collection GIT 542 View Materials : Aispute-41, 1000.5; Ikla, 535.3; Mežmaļi-16, 911.8–912.5; Ruhnu-500, 616.2
the lowermost scabra chitinozoan zone; Nõlvak 2003), 617.4; Vilcini-15,?914.5; collection LDM G: Pliekalni-14,
884.0–884.6.
Remarks.—Small semicircular shells up to 15 mm wide and 10.5 mm long with multicostellate ornament of fine and uniform costellae; the irregular growth lines, partly developed as low rugae, are most similar to those on the Polish specimens of P. polonica ( Temple 1965: pl. 15: 2, 3). The Baltic specimens have obtuse to acute cardinal angles, hinge line 0.9 of valve width. Costellae appear at 2 to 3 mm growth stage; up to 9 costellae per 1 mm at 5 mm from apex, few costellae appear along the posterior margin. Ventral valve very weakly convex around the umbo; dorsal valve flat, anteriorly slightly concave with a low, anacline dorsal interarea with grooved chilidium ( Fig. 4H View Fig 1).
The Baltic specimens differ somewhat from the Polish specimens in shell outline, the ratios of width to length are about 1.4 and 1.6, respectively ( Temple 1965).
The Baltic as well the Polish specimens differ from those from China ( Rong 1984; Zhan et al. 2010) in having somewhat larger shells. The early growth stages, up to 3.5 mm generally lack radial ornament, similar to some specimens of the genus Proboscisambon .
Stratigraphic and geographic range.—This widespread species is mainly restricted to the Hirnantian Stage, Upper Ordovician, although similar forms occur in both the highest Katian and lowest Llandovery. It is common in deeper-water facies in Argentina, Burma, China, Thailand, and parts of Europe, for example, Austria, the Czech Republic, Poland, and England (see, e.g., Benedetto 1990; Rong and Harper 1988; Rong et al. 2002; Temple 1965). In Baltoscandia, it occurs in Sweden ( Bergström 1968), Estonia, and Latvia this paper).
LDM |
Latvian Natural Histotry Museum, department of Entomology |
No known copyright restrictions apply. See Agosti, D., Egloff, W., 2009. Taxonomic information exchange and copyright: the Plazi approach. BMC Research Notes 2009, 2:53 for further explanation.
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Paromalomena polonica ( Temple, 1965 )
Hints, Linda & Harper, David A. T. 2015 |
Paromalomena polonica (Temple)
Cocks, L. R. M. 2008: 63 |
Platymena? polonica
Temple, J. T. 1965: 407 |