Saaremaacrinus estoniensis, Ausich & Wilson & Vinn, 2012
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publication ID |
https://doi.org/ 10.4202/app.2010.0094 |
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persistent identifier |
https://treatment.plazi.org/id/BF03720D-FFCC-FFF0-BC7D-FA932035F99F |
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treatment provided by |
Felipe |
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scientific name |
Saaremaacrinus estoniensis |
| status |
sp. nov. |
Saaremaacrinus estoniensis sp. nov.
Figs. 4A View Fig , 5B View Fig .
Etymology: After Estonia.
Holotype: TUG 1395−3.
Type locality: Kaugatuma Cliff, Saaremaa Island, Estonia.
Type horizon: Äigu Beds, Kaugatuma Formation, Pridoli, Late Silurian.
Material.— Holotype only.
Diagnosis.—As for genus.
Description.—The calyx is medium in size for the family, and it has a medium bowl shape ( Fig. 4A 4 View Fig ) with a slight proximal protrusion of the basal circlet. The basal concavity is absent; no calyx lobation is present; arms are grouped ( Fig. 5B View Fig 2); and calyx plates are gently convex, have smooth sculpturing, and are relatively thick. Calyx plates in rays are more broadly convex yielding a slightly raised, broad ray ridge ( Fig. 5B View Fig 1 View Fig ). Basal circlet has a slight protrusion proximally, is relatively high, is visible in side view, and is approximately 10% of calyx height. The three basal plates are subequal in size. The radial circlet is approximately 18% of calyx height, interrupted in posterior by primanal, and is comprised of five, hexagonal radial plates that are approximately 1.1 times wider than high and subvertical in orientation. Normal interrays are in contact with the tegmen. The first interradial is hexagonal, approximately as high as wide, smaller than radials, and slightly smaller than first primibrachials. The second range has two plates of unequal size. Normal interray plating is 1−2−2−2−2− 2 in alternating ranges yielding a biseries of alternating plates ( Fig. 4A View Fig 1 View Fig ). The CD interray is wider than others and not depressed. The primanal is heptagonal, approximately 1.1 times higher than wide, smaller than radial plates; and it interrupts the radial circlet. Plating in the CD interray is P−3−3−3− ( Fig. 4A View Fig 3 View Fig ) with at least five ranges of plates in CD interray. The anitaxis is defined by more elongate plates through the CD interray, but an anitaxial ridge is absent. The CD interray is in contact with the tegmen. The first primibrachial is fixed, hexagonal, approximately 1.3 times wider than high, and approximately the same size as radials. The second primibrachial is axillary and pentagonal. Commonly five secundibrachials are fixed in the calyx. First secundibrachials in sutural contact medially. Fixed rays are symmetrical. Intrabrachial plates are in the center of the ray, begin on upper shoulder of first secundibrachials ( Fig. 4A View Fig 2), and are in contact with tegmen.
The tegmen is low and robust, has an inverted cone shape ( Fig. 5B View Fig 1 View Fig ), and is slightly depressed interradially The tegmen is composed of small, slightly convex plates with smooth sculpturing. The anal opening is slightly eccentric, and the anal tube interpreted to be absent.
There are 10 free arms but further details unknown.
Only the proximal few, immature columnals are preserved but poorly preserved. They are circular and holomeric, and the columnal height of the most−proximal columnals is variable. The lumen is circular.
Discussion.—The holotype is a complete theca that is in part weathered or has a dark calcite overgrowth so that distinction of the plating is not always possible. However, the posterior interray, other interrays, and enough rays are adequately preserved to permit the plating of this new crinoid to be confidently determined.
Measurements.—TUG 1395−3: calyx height, 11.5; calyx width, 12.0; radial plate height, 3.4; radial plate width, 3.6; first primibrachial height, 2.6; first primibrachial width, 2.8; primanal height, 3.4; primanal width, 3.4; and tegmen height, 5.4.
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