726
Journal of Paleontology 91(4):715–734
Dalicrinus hammanni new species Figures 4.6, 5.1–5.6
Type material.—The holotype (MPZ2016/94) and two para- types (MPZ2016/90, 100).
Diagnosis.—Anthracocrinid with medium bowl-shaped calyx; prominent median ray ridges; infrabasals confined to basal concavity; regular interrays with numerous (>20) plates, plating 1–3 proximally, irregular in higher ranges; fixed intrabrachial plates between fixed secundibrachials and tertibrachials of adjacent half rays and between fixed tertibrachials of adjacent quarter rays; fixed pinnules on lateral margins of fixed rays; 20 free arms; arms grouped by half rays; arms unbranched; brachials wedge chisel biserial.
Occurrence.—Fombuena Formation, Huerva Member, upper middle Berounian (lower Katian, Upper Ordovician), near Fombuena (Zaragoza province), Spain; Localities 1 and 2.
Description.—Calyx medium bowl shaped, slightly higher than wide; circlet plates, lower fixed brachials, and lower interradial plates ornamented with stellate ridges; intrabrachial and higher interradial plates bulbous, ornamented with irregular ridges; plate sutures flush with plate surface on fixed brachials, depressed between interradial plates; ray ridges prominent. Infrabasal plates five, wider than high, confined to the basal
concavity. Basal circlet forming rim of basal concavity, visible in side view; basal plates five, hexagonal, tapered distally, wider than high, proximally flared to form the rim of the basal concavity. Radial circlet interrupted in all rays; radial plates five,
pentagonal, wider than high. Regular interrays wide, in contact with tegmen, not depressed, interrupting the radial circlet in all rays. First interradial plate large, hexagonal, wider than high; second range with three plates, followed by 5? plates in the second row; higher rows with variable plating pattern and plate size; at least 20 plates total per interray in at least seven rows. Posterior interray not observed or undifferentiated. First primibrachial fixed, rectangular, wider than high;
second primibrachial axillary, pentagonal. Secundibrachials two, second secundibrachial axillary; three fixed tertibrachials incorporated into calyx. Fixed intrabrachial plates between fixed secundibrachials and tertibrachials of adjacent half rays,
Tegmen, anal opening, stem, and holdfast unknown.
Etymology.—Hammanni, in recognition of Wolfgang Ham- mann, who contributed much to the study of Ordovician strati- graphy of the Iberian Chains.
Measurements.—Holotype and paratype measurements are given in Table 2.
Family Rhodocrinitidae Roemer, 1855 Genus Ambonacrinus new genus
Type species.—Ambonacrinus decorus new species, by monotypy.
Diagnosis.—As for species, by monotypy.
Etymology.—Ambonacrinus, after the Greek ambon for ridge or crest, in reference to the prominent anitaxial ridge in the posterior interray.
Remarks.—Ambonacrinus decorus is known from a single specimen. Because the plates are very tightly sutured and minimal disarticulation has occurred, it is difficult to determine plating of the regular interrays beyond the first interradial plate. Despite this uncertainty of plating in the regular interrays, Ambonacrinus can be assigned to the Rhodocrinitidae because of the presence of radials separated in all interrays and 10 free arm openings. It is most closely allied with the Group II rhodo- crinitids (Ausich, 1986) on the basis of its prominent median ray ridges, uniserial arms, and medium bowl-shaped calyx. The condition in Ambonacrinus of an anal series
proximal plating 1-2-2-2-2; fixed intrabrachial plates between fixed tertibrachials of adjacent quarter rays, forming a single column of three plates that decrease in size distally. Fixed pinnules on lateral sides of each half ray. Arm openings 20, free above the third tertibrachial,
grouped within each half ray; free arms unbranched as known. Brachials cuneate uniserial proximally, wedge chisel biserial distally. Pinnules on every free brachial.
originating from the C-ray primibrachial is unusual in camerate crinoids (Gahn, 2015) and clearly designates Ambonacrinus as a new genus. Other genera described with this condition are Cefnocrinus Botting, 2003 and Pararchaeocrinus Strimple and Watkins, 1955. Cefnocrinus has a medium globose calyx, basals that are wider than high, two rows of plates between the anal series and D ray, arms that become free above the fourth or fifth secundibrachial, fixed pinnules, cuneate biserial arms, and free arms that branch twice isotomously; Pararchaeocrinus has a medium globose calyx, basals that are wider than high, proximally one row and distally two rows of plates between the anal series andDray, arms that become free above the fourth secundibrachial, no fixed pinnules, cuneate uniserial to cuneate biserial arms, and free arms that are poorly isotomously branched at least three times; and Ambonacrinus has a subconical calyx, basals that are as high as wide, one row of plates between the anal series and D ray, arms that become free above the second or third secundibrachial, no fixed pinnules, rectilinear uniserial to weakly cuneate uniserial arms, and free arms that branch once isotomously.
Figure 5. Crinoids from the Fombuena Formation of Spain. (1–6) Dalicrinus hammanni n. gen. n. sp.: (1) lateral view of partial crown with incomplete arms, holotype, MPZ2016/103; (2) lateral view of calyx and partial arms, paratype, MPZ2016/100; (3) lateral view of calyx and partial arms, paratype, MPZ2016/100; (4) basal view, paratype, MPZ2016/100; (5) lateral view of distal portion of calyx, paratype, MPZ2016/90; (6) internal view of partial calyx, paratype, MPZ2016/ 90; (7) Eopatelliocrinus hispaniensis n. sp., lateral view of crown and partial stem, holotype, MPZ2016/81; (8–10) Picassocrinus villasi n. gen. n. sp., part and counterpart, holotype, MPZ2016/83; (8) CD-interray view of calyx with partial arms; (9) CD-interray view of calyx with partial arms and stem; (10) lateral view of calyx with partial arms and stem.
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