Cantabriastraea cantabrica gen. et sp. nov., 2003

Schröder, Stefan & Soto, Francisco, 2003, Lower Devonian (Emsian) rugose corals from the Cantabrian Mountains, northern Spain, Acta Palaeontologica Polonica 48 (4), pp. 547-558 : 553-556

Cantabriastraea cantabrica gen. et sp. nov.

Figs. 6A, B , 7A–D , 8A–J, 9 A–C .

Holotype: DPO 14780 ( Fig. 6 ). Type locality: Colle , ca. 5 km SE of Boñar, Province León ; Hoja 104 3.5– 5 mm. Tabulae complete and slightly arched (13–18 (Boñar), 1°33’37’’E / 42°50’42’’N. tabulae per 5 mm vertically).

Type horizon: Lower Devonian, Emsian, La Vid Group, upper part of

Description.—Coralla are typically small, with a diameter of the Valporquero Formation (COL A−1) and lowermost part of the

Coladilla Formation (COL B−3). 5–7 cm at a maximum height of 5 cm and have a distinctive Derivation of the name: The name derives from the Cantabrian Moun− growth form of a flat cake. Small colonies are mushroom tains. shaped and comprise only a few corallites ( Fig. 7C ), whereas Paratypes: 34 specimens, DPO 14781–14804, 14809–14814, 14828– adultcoloniestypicallyhaveaslightlydomedsurface.Growth 14830. starts with the development of a single, cylindrical protoDiagnosis.—Type species of Cantabriastraea with corallite corallite, reaching a maximum diameter of 2 cm ( Fig. 8C). diameter of 8–13 mm and 19–24 major septa, which do not This corallite is increasingly replaced by offsets developed by reach the corallite axis. Diameter of tabularium ranges from nonparricidal, marginal increase ( Fig. 8F, H) and transformed Ą to colonial growth. Apical portions of those protocorallites are not preserved. Some fragments show an attachment to corallite fragments of Synaptophyllum multiseptatum Soto , which has obviously been used as hardground. Colony surface is usually well preserved and calices show an everted calicular plane with a deeply depressed and flat central part ( Fig. 7A, D ). Growth form is astreoid−thamnasterioid, but septa are rarely confluent and limitations of corallites are usually marked by break down of septa. There are no true corallite walls. Calical centres are 8–13 mm apart, but can reach to 17 mm in juvenile coralla consisting of only a protocorallite and few smalloffsets( Fig. 8H). Morphology ofsepta ishighly variable within a colony as well as in individual corallites. Septa are usually thin near the corallite boundary, but moderately thickened and may bear numerous irregular carinae or lateralspines(vepreculae)intheirmiddlepart( Fig.9C ).Close to the dissepimentarium boundary they are usually strongly thickened and may be in lateral contact ( Fig. 8D). Carinate septa show a strong tendency to break down into discrete trabeculae giving septa a spongy, retiform morphology. Isolated groups of trabeculae are usually connected by numerous sections of lateral dissepiments, which gives the impression of very broad septa ( Figs. 7A , 8J). Trabecularthickening ofsepta ( Fig. 9C ) increases towards the tabularium border where they are flanked by numerous coarse carinae. However, there are colonies or corallites with very weak or even smooth septa, which are not affected by any septal degeneration ( Fig. 8H). Particularly septa in corallites of small colonies and protocorallites( Fig. 8C)are weakly carinate. Majorsepta vary from 19–24 in number, but can reach up to 31 in a protocorallite ( Fig. 8C). Although there are rhopaloid septa in some corallites, they are generally very slender within the tabularium and do not reach the corallite axis, so that a small axial space of 3.5– 5 mm remains free, which is traversed by rare sections of tabulae. Minor septa barely extend into the tabularium. Sections of axially convex dissepiments are numerous, but are increasingly replaced by irregular or lateral dissepiments towards the periphery. Diameter of tabularia ranges from 3.5–5 mmand includespredominantly complete and slightly convex tabulae which are arranged above one another or are supplemented with peripheral tabellae. There are 13–30 tabulae/cm corallite length. The boundary to the dissepimentarium is characterized by steeply inclined globular dissepiments and accordingwiththeevertedcalice,thedissepimentallayersarestrongly arched ( Fig. 8E, G). They are commonly traversed by fanning monacanth trabeculae, which are arranged perpendicular to the dissepiments and may show bifurcations ( Fig. 9A, B ).

Occurrence.—Only known from the type locality.

Figures

Fig. 6. Cantabriastraea cantabrica gen. et sp. nov. A. Cross section of holotype DPO 14780. B. Longitudinal section of the same. Both × 2. Specimen from the Upper Emsian of Colle.

Fig. 7. Cantabriastraea cantabrica gen. et sp. nov. A. Colony DPO 14811 consisting of a large protocorallite disrupted by nonparricidal, marginal increase in distal view (A1); septa appear as broad and flat ridges which are stronglyretiformtowardstheperiphery.Undersideofthesamecolony(A2), partly encrusted by Aulopora sp.; × 2. B. Colony DPO 14813. B1. Colony underside showing a single protocorallite turned to the left. B2. Upper surface of the same colony; × 1. All specimens from the Upper Emsian of Colle.

Fig. 9. A. Cantabriastraea cantabrica gen. et sp. nov., specimen DPO 14789. A1. Cross sec− tion of tabularium and inner dissepimentarium. Trabeculae are oriented perpendicular to the rows of dissepiments; × 15. A2. Detail of A1; trabeculae intercalate between existing ones or bifurcate; × 20. A3. Septa in cross section with strong dilations in inner dissepimentarium caused by thickening of trabeculae. Towards the periphery (left side) septa become irregular carinate and may split into discrete trabeculae; × 24. B, C. Tabulophyllum bonarense sp. nov. B. Wall of corallite DPO 14673 in cross sec− tion. Thickenings of wall and lonsdaleoid dis− sepiments show a fibrous structure caused by thickened septal bases; × 24. C. Thin septa of corallite DPO 14686 (compare with Fig. 4G) inserting on lonsdaleoid dissepiments (dark lines in lower part of picture). Central part to− wards the axis (top of picture) is strongly af− fected by cement; × 24. All specimens from the Upper Emsian of Colle.