Valiukia flabellata, Karatajūtē-Talimaa & Märss, 2002
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publication ID |
https://doi.org/ 10.5281/zenodo.5375097 |
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persistent identifier |
https://treatment.plazi.org/id/AB0B878D-0F69-FFE1-801A-FE65B6C6258A |
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treatment provided by |
Marcus |
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scientific name |
Valiukia flabellata |
| status |
sp. nov. |
Valiukia flabellata n. sp. ( Figs 12-15 View FIG View FIG View FIG View FIG )
Valiukia sp. 1 Märss & Karajūtē- Talimaa 2002: fig. 1.
HOLOTYPE. — Trunk scale LIG 35-844 ( Fig. 14A, B View FIG ) and the same restored ( Fig. 12G View FIG ).
ETYMOLOGY. — From the Latin word flabellata : fanshaped.
TYPE LOCALITY AND AGE. — Sample 2-23, Matusevich River, Ust-Spokojnaya Formation, Ludlow, Upper Silurian.
MATERIAL EXAMINED. — Over 170 scales of different preservation.
DIAGNOSIS. — Scales very small, 0.2-0.7 mm long. Head scales rounded, irregularly shaped, with low flat crown having deep marginal cuts. Transitional scales oval, rhomboidal, sometimes rather wide. Central area of the crown is distinct anteriorly or along all its length ; one or two pairs of shorter lateral areas separated from the central one by deep grooves having transverse ridgelets; the crown is posteriorly multipointed. Some of small transitional scales have high neck and a base smaller than the crown. Trunk scales are the largest, elongated and rhomboidal or short and oval. The central area of the crown is rhomboidal and narrow, and higher than the remaining part of it. The lateral areas, two to three on each side, are separated from each other by longitudinal ridgelets which are more distinct on the crown surface posteriorly. Postero-lateral parts of the crown are made of the very narrow longitudinal posteriorly pointed spines. The medial spine is the longest. In comparatively wide oval scales the spines are long and distributed fan-wise. On the surface of longitudinal spines, fine longitudinal ridgelets of the sculpture are distributed. On the lower surface of the crown, the longitudinal spines are tightly joined to each other and only posteriorly they end independently. Usually the longitudinal spines are situated on different levels and cover partly the neighbouring ones. The base is low, placed anteriorly, sometimes with an anterior spur-like projection. The microstructure is of loganelliid type.
DESCRIPTION
Morphology
The morphology of head, transitional and trunk scales is very different. The head scales are very small (0.2-0.3 mm in diameter), rounded, oval, sometimes of irregular shape. The crown is low, flat and with deep marginal crenulation ( Figs 12A, B View FIG ; 13A, B View FIG ). The base is a little larger than the crown, slightly convex, and only seldom rather high. Transitional scales show some morphological varieties ( Figs 12 View FIG C-F; 13C-I).
In type “A” the central area of the crown is developed only in its anterior part ( Figs 12C, D View FIG ; 13C, D View FIG ). The central area is separated from the lateral ones with deep longitudinal notches. The lateral areas, one to two on each side, are short, and separated from each other by shallow grooves. The crown surface is smooth and flat, and posterior crown margin multicuspidate. Some of the cusps are situated on the inferior level between those which are placed higher.
In type “B” the central area of the crown is completely separated from the shorter lateral areas by deep longitudinal grooves. Anteriorly of the central area is developed a shallow medial notch; posteriorly, this area is pointed and keellike. The posterior margin of the crown multicuspidate and composed of several pointed spines ( Figs 12F View FIG ; 13G, H View FIG ). Lateral areas are only partly ( Figs 12E View FIG ; 13E View FIG ) or completely ( Figs 12F View FIG ; 13G, H View FIG ) separated from each other. In several transitional scales of type “B” the crown is rather wide and rhomboidal.
In the deep grooves of both types, a peculiar morphological element, transverse ridgelets (see close-ups in Fig. 13F, G View FIG ) are discovered in thelodonts for the first time. The base of the transitional scales is rhomboidal, not very high and slightly convex. Comparatively small pulp opening in the posterior corner of the base cannot always be observed. The neck of scales of type “B” is comparatively higher. The size of transitional scales is 0.2-0.35 mm but the small scales of type “B” can be even smaller than 0.1 mm.
In Fig. 13I, a View FIG transitional(?) scale with features rather similar to trunk scales is presented. The central area of its crown is narrow and higher than the rest of the scale surface like in trunk scales but the longitudinal spines on the postero-lateral part of the crown are short; in their shape and size lateral areas of the crown are nearly the same as in transitional scales.
Trunk scales are comparatively larger and in rare cases can reach a length up to 0.65-0.7 mm, on average 0.3-0.55 mm ( Figs 12 View FIG G-J; 13J, K; 14). Most scales are oval to rhomboidal; they can be wide or narrow, with the crown posteriorly shifted. Central area of the crown is narrow, rhomboidal, with a flat smooth surface and separated from the lateral areas with a step being on a higher level than the remaining part of the crown. The anterior part of the central area is rather short; posterior part is pointed and can become like the medial longitudinal spine.
Among the trunk scales two morphological varieties have also been established. Type “A” contains the scales with relatively wide complicated fan-shaped crowns ( Figs 12G, H View FIG ; 14 View FIG A-D) and type “B”, the relatively narrow elongated crowns ( Figs 12I, J View FIG ; 14 View FIG E-G, J-M).
In the crown of type “A” scales, the lateral areas, two to three on each side, are distinct. They are separated from the central area and each other by grooves. Posteriorly the crown is composed of numerous narrow longitudinal spine areas, a medial and 10 to 14 or more pairs of lateral ones. The spines are situated on different levels, some of them being on higher and some on lower levels, beneath the former. The surface of lateral areas of the crown is covered with longitudinal ridgelets that go over into the longitudinal spines. Type “A” corresponds to scales with long longitudinal fan-shaped spines. The posterior points of the spines end separately; sometimes the spine is independent along its whole length (see Fig. 12H View FIG ). The base is relatively low and short, oval to rhomboidal. A relatively small pulp opening is situated in the posterior corner of it.
In the crown of type “B” trunk scales, the central area is strongly elevated when compared with remaining part of it. In Figs 12I View FIG and 14E View FIG , the same trunk scale with a rather wide crown, with oval-rhomboidal and rather wide and short central area is illustrated. In trunk scales from the posterior part of the body, the crown is elongated and its central area is narrow and relatively high ( Figs 12J View FIG ; 14F, G, J, K View FIG ). Lateral areas are separated from each other with ridges or furrows which are more distinct anteriorly. On the postero-lateral parts of the crown they disappear between the longitudinal ridges which become a longitudinal areas-spines. The medial spine is the longest, the lateral ones being shorter. The posterior points of the spines are usually broken. In Fig. 12 View FIG the length of all spines of the crown is restored. In type “B” trunk scales the longitudinal spines are tightly united to each other as seen in Fig. 13J, K View FIG , and only most posteriorly on the crown, they are separated. In Fig. 14L, M View FIG the scales with comparatively short longitudinal spines, five to six on each side, are presented.
Histology
The microstructure of the scales ( Fig. 15 View FIG A-C) has been studied using anise oil. In the crown of trunk scales the main pulp canal (mpc) and lateral branches of it, and also comparatively fine pulp canals (pc) are present. The latter go into the longitudinal spines and can be rather long ( Fig. 15C View FIG ). The shape and distribution of dentine tubules in the crown is similar to other loganellids.
Family KATOPORODONTIDAE Märss, Wilson & Thorsteinsson, 2000
Genus Phlebolepis Pander, 1856
TYPE SPECIES. — Phlebolepis elegans Pander, 1856 .
Phlebolepis elegans Pander, 1856 ( Fig. 3 View FIG O-T)
SYNONYMY. — See Turner (1976) and Märss (1986b).
MATERIAL EXAMINED. — Over 100 scales, mainly fragmentary material.
OCCURRENCE. — Samples 2-10, 2-11, 2-19, Matusevich River; 157-4, Spokojnaya River; 31-1, Ushakov River, October Revolution Island, Severnaya Zemlya Archipelago, Ust-Spokojnaya Formation, Ludlow, Upper Silurian.
DESCRIPTION AND COMMENTS
In the samples, most of the scale varieties described by Märss (1986b) have been found. As an exception, in this description we use her terminology. Oral (= rostral, the scales come from the rostrum around the mouth): scales are wide and short, with transverse angular ridge on the crown. Cephalo-pectoral ( Fig. 3 View FIG O-Q, S): scales are big, crown surface is smooth or with a gentle longitudinal medial ridge and short ridges antero-laterally. Postero-lateral margins of the crown is finely serrated. Crown surface has fine striation ( Fig. 3S View FIG ). Postpectoral scales are with a wide medial ridge and several lateral ridges on it. Precaudal scales ( Fig. 3R View FIG ) with a strong sharp medial and some lateral ridges. Pulp depression is always widely open. Definite fin scales are absent in our collections.
Genus Goniporus Gross, 1967
TYPE SPECIES. — Goniporus alatus ( Gross, 1947) .
Goniporus alatus ( Gross, 1947) ( Fig. 16 View FIG )
SYNONYMY. — See Gross (1967), Turner (1976) and Karatajūtē- Talimaa (1978).
OCCURRENCE. — On Severnaya Zemlya, the scales of G. alatus have been found only in the Krasnaya Bukhta Formation, Pridoli, of October Revolution Island (Spokojnaya River, outcrops 51a, beds a, b, and c; 45, bed 11; 45, talus; 41, bed 1; MF 157-2). In the sections of the European biogeographic province, G. alatus is characteristic for the lower part of Pridoli ( Thelodus parvidens Zone by Gross 1967; Katoporodus tricavus-Goniporus alatus Zone by Talimaa 2000) but also for the upper part of it ( P. kummerowi and K. lithuanicus-K. timanicus Zones; see Märss et al. 1995). The scales of G. alatus are also rarely represented at the base of Lower Devonian together with the scales of Turinia pagei (Powrie, 1970) ( Turner 1973; Märss 1986, 1997; Karatajūtē- Talimaa 1978; Talimaa 2000).
DESCRIPTION AND COMMENTS
Comparatively small oval, often rhomboidal, and flat scales. Head scales ( Fig. 16A View FIG ) very small (length about 0.4 mm), with crenulated crown margins. These scales are very rare in samples.
Transitional scales are 0.5-0.65 mm long and 0.4- 0.5 mm wide. They are composed of a rather monolithic flat crown with distinct central and lateral areas anteriorly on the crown only ( Fig. 16 View FIG B-D). Trunk scales ( Fig. 16 View FIG E-Q) usually predominate in the samples. Rather wide rhomboidal scales ( Fig. 16 View FIG E-I, O-Q) show a narrow central area with medial furrow and two pairs of lateral areas. Marginal areas short and wing-like. The length of the scales 0.4-0.6 mm, width 0.4- 0.5 mm. The base can be convex; in this case the pulp openings are not visible. The base can be flat and low ( Fig. 16G View FIG 2, O 2, P 2 View FIG ) or wall-like surrounding the pulp depression ( Fig. 16I View FIG 2 View FIG ). Openings of pulp canals are situated at the postero-lateral margins of the base or in the pulp depression. The number of openings depends on the number of crown areas. Anteriorly the base has sometimes spur-like projection ( Fig. 16 View FIG O-Q). Small and narrow scales are composed of the central and a pair of lateral areas that are shorter and wing-like ( Fig. 16 View FIG J-N). The length of the scales is 0.3-0.5 mm and width 0.2-0.3 mm.
COMPARISON
After the size and form of the scales, G. alatus in Krasnaya Bukhta Formation, Pridoli, of Severnaya Zemlya, does not differ from the species of the same age of other regions (Welsh Borderland, erratic boulders of north German lowland, Lithuania, Latvia, Estonia, Kaliningrad District, NE Poland, North Timan, eastern part of Timan-Pechora Region, the Urals and Cornwallis Island; see Turner 1973; Märss 1997; Märss et al. 1998; Talimaa 2000). Still, the morphology to original most similar Goniporus alatus is revealed by the scales from the Pridoli of Severnaya Zemlya and Eptarma Formation of North Timan (Karatajūtē- Talimaa 1978: pl. VI, figs 6-10).
Order THELODONTIDA, Kiaer, 1932 Family THELODONTIDAE Jordan, 1905
Genus Thelodus Agassiz, 1839
TYPE SPECIES. — Thelodus parvidens Agassiz, 1839 .
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.
