Protasterina flexuosa ( Miller and Dyer, 1878 )
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publication ID |
https://doi.org/ 10.5281/zenodo.13643683 |
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persistent identifier |
https://treatment.plazi.org/id/0392F57C-2E4D-DA43-0B1D-FEBF9BFB9CBF |
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treatment provided by |
Felipe |
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scientific name |
Protasterina flexuosa ( Miller and Dyer, 1878 ) |
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Protasterina flexuosa ( Miller and Dyer, 1878)
Figs. 1–3 View Fig View Fig View Fig , 4A View Fig 1 –A View Fig 3 View Fig , 5 View Fig . 1878 Protaster flexuosus sp. nov.; Miller and Dyer 1878: 31, pl.2: 1, 1a. 1878 Protasterina (“ Protaster ” lapsus) fimbriata gen. nov., sp. nov.;
Ulrich 1878: 95–96, pl. 4: 9, 9a–c. 1878 Protaster flexuosus Miller and Dyer ; Ulrich 1878: 96. 1880 Protasterina fimbriata Ulrich ; Ulrich 1880: 10. 1880 Protasterina flexuosa (Miller and Dyer) ; Ulrich 1880: 10. 1883 Protaster flexuosus Miller and Dyer ; Miller 1883: 287. 1888 Taeniaster fimbriata (Ulrich) ; Ulrich 1888: 184, 313. 1888 Taeniaster flexuosa (Miller and Dyer) ; Ulrich 1888: 184, 313. 1889 Protaster flexuosus Miller and Dyer ; Miller 1889: 276, fig. 409. 1896 Protasterina fimbriata Ulrich ; James 1896: 139–140. 1896 Protasterina flexuosa (Miller and Dyer) ; James 1896: 140. 1902 Taeniaster fimbriatus (Ulrich) ; Nickles 1902: 70. 1902 Taeniaster flexuosus (Miller and Dyer) ; Nickles 1902: 70. 1908 Protaster flexuosus Miller and Dyer ; Parks 1908: 364. 1908 Protasterina fimbriata Ulrich ; Parks 1908: 368. 1914 Alepidaster flexuosus (Miller and Dyer) ; Schuchert 1914: 11. 1915 Alepidaster flexuosus (Miller and Dyer) ; Schuchert 1915: 231–233,
pl. 36: 4. 1915 Alepidaster flexuosus (Miller and Dyer) ; Bassler 1915: 25. 1915 Alepidaster fimbriatus (Ulrich) ; Bassler 1915: 25. 1934? Taeniaster spinosus (Billings) ; Spencer 1934: 491, pl. 31: 10. 1934? Drepanaster flexuosus (Miller and Dyer) ; Spencer 1934: 491. 1940 “ Protaster ” flexuosus (Miller and Dyer) ; Spencer 1940: 497. 1962 Protasterina fimbriata Ulrich ; Hansman et al. 1962: 102. 1965 Taeniaster fimbriatus (Ulrich) ; Owen 1965: 550. 1970? Protasterina flexuosa (Miller and Dyer) ; Hotchkiss 1970: 73. 1986 Protasterina fimbriata Ulrich ; Hammann and Schmincke 1986:
61, text−fig. 3. 1995 Protasterina fimbriata Ulrich ; Hotchkiss 1995: 433, table 6. 1999 Protasterina fimbriata Ulrich ; Hotchkiss et al. 1999: 192. 2002 Protasterina fimbriata Ulrich ; Glass and Blake 2002: 36.
Diagnosis. —Same as genus by monotypy.
Material.— Fifteen specimens housed at CMC and MCZ: MCZ 108078 About MCZ a (lectotype by designation herein), MCZ 108078 About MCZ b, MCZ 108079 About MCZ (paralectotype), MCZ 108086 About MCZ , CMC 25001 View Materials , CMC 25002 View Materials , CMC 25003 View Materials (three specimens), CMC P3874 View Materials (two specimens), CMC P50635 View Materials (four specimens). Details on preservation and condition of specimens are given in the Appendix 1 .
Description. —The interradial margin of the disk is rounded to straight and lacks marginal ossicles ( Figs. 1B View Fig , 3A View Fig 1 View Fig ). The ventral and dorsal surface of the disk is covered by closely abutting ossicles and in at least one specimen these are well−enough exposed to show that they are shaped like fourpointed stars ( Fig. 5E View Fig 3 View Fig ). Fine granules are irregularly distributed across both the ventral and dorsal disk surfaces ( Figs. 1B View Fig , 3B View Fig 2 View Fig ). Very fine evenly tapering spines are present on each side of the disk though they appear to have been denser on the ventral surface. Some spines are as long as the lengths of the laterals ( Fig. 3B View Fig 2 View Fig ). A madreporite is present. It is a small, rounded, slightly raised plate−like ossicles with a wavy circumferential channel. The channel has five loops that are raised toward the upper surface of the ossicle. It is situated next to the second lateral ( Figs. 1D View Fig , 3B View Fig 2 View Fig ).
None of the available material adequately exposes the dorsal surface of the mouth frame so description is limited to its ventral aspects ( Figs. 1C View Fig , 5B View Fig ). The mouth−angle ossicles (first ambulacrals) are not significantly longer than the length of the proximal ambulacrals. Their ventral surfaces are broad with a centralized depression that is surrounded by a distinctly raised margin. Adradially, this margin varies from flat to exhibiting raised bumps. In at least one place the remains of what might have been spines are associated with these bumps ( Figs. 1C View Fig , 2D View Fig ). The proximal ends of the mouth angle ossicles abut to form scoop−shaped depressions facing towards the center of the mouth. The proximalmost edges of the mouth angle ossicles are slightly raised, increasing the size of these elongated depressions inside the mouth. Several small spines extend from the mouth−angle ossicles into the mouth area. A torus could not be clearly identified; however, in at least one place the spines appear to come together and attach to a small base or possible torus that does not completely fill the scoop−shaped depression. The laterals of the second ambulacral, some affiliated with preserved buccal tube feet ( Fig. 1C View Fig ), are clearly differentiated from the mouth−angle ossicles by a skeletal gap. They are small, subquadrate, and slightly concave abradially. They are distinctly raised above the level of both the arm surface and the mouth−angle ossicles. The ventralmost edge carries at least three petaloid spines.
Arms are widest at the disk margin and taper evenly beyond the disk ( Figs. 1A View Fig , 3B View Fig 1 View Fig ). All arm tips are missing in available specimens. The dorsal surface of the arms is exposed in all specimens showing the ambulacrals below. The dorsal surface of the ambulacrals is finely granulated. Whether this represents the granulated surface texture of the ossicles or remnants of granulated skin cannot be determined. Evidence for a carinal row of spines or ossicles is absent. The dorsal interambulacral muscle gaps are wide, giving the ambulacrals a trapezoidal to nearly triangular dorsal outline ( Fig. 1G View Fig ). This shape is most pronounced in the free arms just outside the disk ( Fig. 3A View Fig 2 View Fig ). The ambulacrals are fringed distally and proximally by raised ridges, which decrease in height along the arm.
The number of ambulacrals in the disk varies between three and five but can appear to be greater when the disk is distorted or folded underneath the arms. The ventral surface of the ambulacrals is typically boot−shaped with a shallow saddle in the middle of the leg ( Figs. 1F, H View Fig , 3B 3 View Fig , 5E View Fig 4 View Fig ). Small, rounded depressions at the ankle of the boot are clearly absent. In the proximal ambulacrals (up to the fifth), the foot is as wide (WF, abbreviations follow Glass and Blake 2004: fig. 6B) as the leg is long (LL) ( Figs. 3B 3 View Fig , 4A View Fig 1 –A View Fig 3 View Fig ). This also applies to the first two to three ambulacrals immediately outside of the disk ( Fig. 5E View Fig 4 View Fig ) but distally along the arm, the width of the foot becomes shorter than the lengths of the leg creating a distinctive hour−glass appearance ( Figs. 1H View Fig , 4A View Fig 1 – A View Fig 3 View Fig ). Description here focuses on the ambulacrals immediately outside of the disk ( Figs. 4A View Fig 1 View Fig , 5E View Fig 4 View Fig ). The length of the toe (LT) is slightly less than half the length of the leg (LL). The length of the foot (LT) is nearly equal to the width of the distal fitting (WDF). All of the articulation sites—distal, proximal, and toe—are straight. The surface of the ventral interambulacral muscle articulation bears small ridges ( Fig. 5E View Fig 2 View Fig ). The width of the distal fitting (WDF) is larger than the width of the central leg (WCL). The width of the foot (WF) is greater than the width of the distal fitting (WDF). The width of the toe (WT) is nearly half the width of the foot (WF). The lace area of the boot is nearly circular from toe to distal fitting ( Figs. 1F View Fig , 3B 3 View Fig ). The podial basin is triangular in shape due to the large dorsal interambulacral muscle gaps ( Fig. 5E 5 View Fig ). Because the width of the central leg (WCL) is distinctly less than the distal fitting, the ventral median suture is distinctly sinuous and almost angular ( Figs. 1H View Fig , 3B 3 View Fig ).
The laterals are slightly curved abradially but appear nearly straight in ventral view ( Fig. 1H View Fig ). They articulate to the ambulacrals by a prominent, thin, straight neck ( Fig. 1F View Fig ). The lateral edge bearing the groove spines is sharply raised above the articulating neck. Consecutive laterals imbricate along the arm. Laterals bear both groove and vertical spines ( Figs. 1F, H View Fig , 5E View Fig 4 View Fig ).
The exact number of groove and vertical spines per lateral is difficult to ascertain because of the small size of the specimens as well as vagaries of preservation. A maximum of five groove spines can be seen on laterals of arms inside the disk. In places, there is also evidence for a sixth spine on the distalmost corner of the spine−bearing ridge, but this could also be the ventralmost lateral spine. Most of the tips of the groove spines are broken off but partial preservation in places suggests that they are of variable length. Their small size makes it difficult to judge their shape. Many of them appear to taper evenly to blunt tips, others seem slightly petaloid. Whenever preserved, a lateral’s groove spines generally point in the same direction.
Disk laterals bear one, or perhaps two vertical spines that articulate along the distal, slightly abradial edge of the lateral. None of the vertical spines are preserved in their full length but the maximum preserved size reaches the length of a lateral. Some vertical spines bear a distinct axial groove. Along the proximal free arms, at least four vertical spines are present on each lateral. The ventralmost vertical spine is the longest and spine size decreases along the lateral’s proximal edge. The vertical spines on the free arms are preserved parallel to the arm axis. Where vertical spines are lost, distinct articulation sites are visible along the lateral’s edge.
Occurrence.—Same as genus. For details on available stratigraphical and geographical infornation see Appendix 1.
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.