Entomoprimitia (Entomoprimitia) Kummerow, 1939

Olempska, Ewa, 2002, The Late Devonian Upper Kellwasser Event and entomozoacean ostracods in the Holy Cross Mountains, Poland, Acta Palaeontologica Polonica 47 (2), pp. 247-266 : 256-258

Subgenus Entomoprimitia (Entomoprimitia) Kummerow, 1939

Entomoprimitia (Entomoprimitia) splendens ( Waldschmidt, 1885) .—This species ( Figs. 6A–I, 10C–E ) is common in the pre−event part of the Płucki section. It occurs also in the Kowala section (samples Kw−117–130; see also Vishnevskaya et al. 2002: figs. 1, 2). Some well preserved complete carapacesandsinglevalveswererecovered,butthemajority of specimens are poorly preserved single valves. The specimens of E. (E.) splendens from Płucki are marked by a considerabledegreeofvariability.Therearethreeratherdistinct forms which seems to be within the range of variation of E. (E.) splendens . They mostly differ in the arrangement and spacingoftheribs.Form1( Fig.6B–G)ischaracterisedbya lateral outline broadly oval. The dorsal margin is slightly curvedandtheventralmarginisgentlyrounded.Theanterior end is more narrowly rounded than the posterior end. The musclepitisprominentandcircular.Thesurfacebearsabout 40fineribsofequalstrength,concentricallyarrangedaround themusclepit.Theintercalatedandbifurcatingribsarepresent. The inner ribs are curved and join each other near the dorsal margin. In well preserved specimens it is visible that theouterribswithverynarrowintercostalspacesrunconcentrically parallel and close to the dorsal margin. The variable numbersofribsaredeflectedoutwardsinasigmoidalefashion towards the anterior and posterior margins below the mid−height. The intercostal spaces are slightly wider in the anteriorpartofthecarapace.Specimensof E.(E.) splendens from the UKWH ( Fig. 10C–E ) are probably juvenile forms. They are similar to those illustrated by Matern (1929: pl. 1: 5a–c), Blumenstengel(1959:pl.2:8), Casier(1982a:pl.1:3), and those illustrated by Casier and Lethiers (1998a: fig. 3d).

Form 2 ( Fig. 6A) is distinguished by the almost straight dorsal margin and slightly trembling ribs.

Form3( Fig.6H–I)ischaracterisedbydenselyspacedribs intheposteriorpartofthecarapaceandwideintercostalspaces intheanteriorpartofthecarapace.Ribsintheposteriorpartof the carapace run at a slight angle to the inner rib surrounding theroundanddeepmusclepit.Thisformissomewhatsimilar to Entomoprimitia (Reptiprimitia) species,fromwhichitmay bedistinguishedbytheabsenceofsulcus.Itseemstobepossiblethatform3shouldbeexcludedfrom E.(E.) splendens,but the poor state of preservation of specimens available, precludes the possibility of separating new species.

Considerable intraspecific variability of the taxon has already been pointed out by other authors ( Rabien 1954; Groos−Uffenorde 1984) who described narrow and coarsely ribbed forms. Similar is the case of the material under study in which differences may be observed which are even more distinct than those described by these authors. The polymorphism observed within this species is also present in several otherspecies,especiallyin E. (E.) sartenaeri .Itseemspossible that Entomoprimitia (E.) rotundata ( Polenova, 1955) from the late Frasnian of the Volga−Ural region ( Polenova 1955: pl. 14: 2) should be included in E. (E.) splendens , but takenasaprecursorof E.(E.) splendens byKrebsandRabien (1964: 97).

Range and occurrence.—Thisspeciesisrestrictedtothelate Frasnian, E. (E.) splendens Zone , of Europe (Rhenish Slate Mts., Harz Mts., Thuringia, Ardennes, Great Britain, Holy Cross Mts.), and South China.

Entomoprimitia (Entomoprimitia) nitida ( Roemer, 1850) .— This large species ( Fig. 7A, B ), up to 1.85 mm in length and 1.60 mm in height, with a finely−ribbing surface pattern is common in the pre−event part of the Płucki section (samples P−13 to P−124). The shell is equally convex and the dorsal margin is straight. The anterior and posterior ends are rounded, the posterior one more broadly. The adductorial sulcus is long and wide and reaches below the mid−height of the carapace. In its ventral part, the sulcus is curved anteroventrally, and expands into an elongated muscle pit. A low indistinct ridge−like elevation usually surrounds the ventral partofthesulcusinadultforms.Thedeepdepressionispresent in the dorsal part of the sulcus. The surface bears 40–50 fine, narrow ribs of equal strength, concentrically arranged around the sulcus and the muscle pit. A few bifurcatory and intercalatory ribs are usually present.

Specimens from Płucki differ from those illustrated by Rabien (1954: pl. 3: 24) and Müller−Steffen (1964: pl. 18: 2) inhavingalongerandwidersulcus.Theyarequitesimilarto thespecimensof E.(E.) nitida illustratedbyCasier(1975:pl. 3:1)fromtheMatagneFormationofBelgium.Itseemspossible that Entomoprimitia (E.) sarailensis ( Polenova, 1955) from the late Frasnian of the Volga−Ural region ( Polenova 1955: pl. 14: 1) should be included in this species, as proposed by Krebs and Rabien (1964).

Range and occurrence.—This species is known from the middle and late Frasnian, Waldeckella cicatricosa up to the E. (E.) splendens zones, of Europe and South China.

Entomoprimitia (Entomoprimitia) sartenaeri Casier, 1975 . —This species ( Figs. 8A–H, 10B ) occurs in the pre−event and event part of the Płucki section. (samples P−4 to P−126). This relatively large−sized species (up to 2.3 mm in length), showsaratherhighdegreeofvariationintheribbingpattern, partly due to the slight deformations of the carapace. It is characterised by the broadly oval lateral outline of the carapace, slightly convex to almost straight dorsal margin, and deep circular muscle pit. The surface bears 15 to 25 concentric but sigmoidaly deflected ribs. In the material from the Płucki section there are specimens closely similar to the holotype ( Fig. 8B–D, G), but also specimens with more densely spaced ribs ( Fig. 8A), and specimens having intercostal spacing between inner ribs wider than between outer ribs ( Fig. 8H, I). It seems that Entomoprimitia (E.) aff. spiralis (MartynovainPolenova,1955) fromlateFrasnianof the Volga−Ural region ( Polenova 1955: pl. 13: 4) should be included in E. (E.) sartenaeri .

Range and occurrence.—This species is known from the middle and late Frasnian, W. cicatricosa / Rabienella barrandei Interregnum up to the E. (E.) splendens Zone of EuropeandSouthChina,however,Buggischetal.(1978)noted E. (E.) variostriata (= sartenaeri ) vel kayseri from the early Famennian, F. (F.) sigmoidale Zone.

Entomoprimitia (Entomoprimitia) kayseri ( Waldschmidt, 1885) .—This species ( Fig. 10A ) occurs in the Płucki section only in the UKWH (sample P−126a). Probably only juvenile specimens are present. Specimens from Płucki possesses ten concentricouterribs,partlydivided,andfourtofivelongitudinalribsinthemiddlepartofthecarapace.Thedorsalmarginis long and almost straight, and the ventral margin is slightly convex.Alargeswellingispresentintheposterodorsalpartof thecarapaceandasmallpreadductorialnodeispresentbefore the sulcal depression. The sulcus is shallow and short.

Rabien (1954) and Groos−Uffenorde (1984: pl. 2: 9, 10) describedtwoformsofthisspecies:asmallercoarselyribbed formandamuchlargernarrowribbedform.Specimensfrom the Płucki section are most similar to the coarsely ribbed form sensu Rabien (1954).

Range and occurrences.—Thisisoneofthemostcharacteristic species in the UKWH. It is abundant in the upper part of the Kellwasser Horizon in the Steinbruch Schmidt section, RhenishSlateMts.,AeketalandKellwasser−Talsectionsinthe Harz Mts. ( Walliser et al. 1989; Groos−Uffenorde and Schindler 1990; Schindler 1990a, b; 1993; Casier and Lethiers 1998a).However,intheRhenishSlateMts.,itoccursalsobelowtheUKWH( Rabien1954;Buggischetal.1980, Schindler 1993). This species occurs also in the Neuville section in the southern part of the Dinant Basin, Belgium ( Casier 1982a).

Entomoprimitia (Entomoprimitia) sp. aff. E. (E.) wildungensis ( Matern, 1929).—This rare species ( Fig. 7E, F ) in PłuckioccursonlyinsamplesP−18andP−120.Itismostsimilar in its concentrically arranged outer ribs and longitudinally elongated inner ribs to the E. (E.) wildungensis illustrated by Matern (1929: pl. 1: 4a–c).

Range and occurrences.—This species occurs in the Płucki section in the late Frasnian, below the UKWH, E. (E.) splendens Zone.

Figures

Fig. 10. Entomozoacean species from the Upper Kellwasser Horizon (sample P–126, 126a). A1–A3. Entomoprimitia (Entomoprimitia) kayseri (Waldschmidt,1885).RightvalveZPALO.52/23inlateral,obliquedorsalandobliqueventralviews. B1, B2. Entomoprimitia (Entomoprimitia) sartenaeri Casier, 1975.RightvalveZPALO.52/29inlateralandobliquedorsalviews. C–E. Entomoprimitia (Entomoprimitia) splendens (Waldschmidt,1885).C.Leftvalve ZPALO.52/24 in lateral view. D. Right valve ZPALO.52/17 in lateral view. E. Left valve ZPALO.52/18 in oblique dorsal view. Scale bars 500 µm.

Fig. 7. A, B. Entomoprimitia (Entomoprimitia) nitida (Roemer, 1850). A1–A3. Right valve ZPAL O.52/32 in lateral, oblique ventral and oblique dorsal views;sampleP−120. B1, B2.CarapaceZPALO.52/25inrightlateralandobliqueventralviews;sampleP−14. C, D. Rabienella? lagowiensis sp.nov. C1, C2. Rightvalve,holotypeZPALO.52/76inlateralandobliqueventralviews;sampleP−47. D1, D2.CarapaceZPALO.52/60inrightlateralandobliqueventral views;sampleP−a. E, F. Entomoprimitia (Entomoprimitia) sp.aff. E.(E.) wildungensis (Matern,1929). E.CarapaceZPALO.52/68inrightobliqueventral view; sample P−112. F1, F2. Right valve ZPALO.52/37 in lateral and oblique ventral views; sample P−120. Scale bars 500 µm.