Paratelecrinus, Messing, Charles G., 2013

Messing, Charles G., 2013, A revision of the genus Atelecrinus PH Carpenter (Echinodermata: Crinoidea), Zootaxa 3681 (1), pp. 1-43 : 21-22

Paratelecrinus new genus

Atelecrinus PH Carpenter 1881:16 –18 (part); 1882:488–489 (part); 1888:68–70 (part).— Hartlaub 1912:480 –481 (part).—AH Clark 1918:262, 266–267 (part).— Clark and Clark 1967:817 –819 (part).

Diagnosis. A genus of Atelecrinidae with the centrodorsal hollow and thin-walled, separated at least interradially from basal ring by ligament-filled gap; central cavity diameter>0.6 times basal diameter; adoral rim of centrodorsal with 5 hollow, interradial buttresses that open adorally as deep, ring-shaped pits ( Figure 3 c). Cirrus sockets in 10 or 15 columns with fulcral tubercles similar to those of Atelecrinus and Adelatelecrinus but often more strongly developed, producing a strongly serrated centrodorsal profile ( Figures 9 c, 11b, 14b); cirri (when known) with weak opposing spine and curved claw ( Figures 9 d, 11d, 15c, d), of up to 45 cirrals, 94 mm long (possibly also tapering to point with no opposing spine). Externally visible portion of each basal a shallow chevron (=inverted V-shape) (e.g., Figures 9 a–c, 11a–b, 14a) to almost straight (e.g., Figure 13 a, 14b), swollen interradially or not; ends contiguous midradially, often rounded. Aboral surface of basals with spoon-shaped articulation in central depression flanked by a pair of small fossae, and with adorally curved and distally expanded pair of interior projections ( Figure 3 d). Radial cavity apparently lacking delicate aboral calcareous deposit. Most proximal pinnule usually on IIbr17 (rarely IIbr12–20).

Type species. Atelecrinus cubensis PH Carpenter, 1881.

Other included species. Atelecrinus wyvilli PH Carpenter, 1881; Atelecrinus conifer AH Clark, 1908a; Paratelecrinus orthotriremis , new species; Paratelecrinus amenouzume new species; Paratelecrinus laticonulus new species, and Paratelecrinus telo new species.

Remarks. In Atelecrinus , the adoral rim of the centrodorsal bears shallow interradial depressions rather than deep, ring-shaped pits, and the basal ring and centrodorsal are tightly joined ( Figures 3 a, 4). Whereas the aboral surface of the basals in Atelecrinus and Adelatelecrinus bears a shallow, flat, interradial depression ( Figures 3 b, 7e), in Paratelecrinus it is more strongly and intricately sculpted: the aboral surface bears a distinctive central spoon-shaped structure with a short, thick “handle” flanked by deep narrow recesses; the “spoon” itself is roughly teardrop-shaped with the narrow end toward the central cavity ( Figure 3 d). The adoral rim of the centrodorsal bears three small pegs or processes between the raised rims of adjacent deep interradial pits ( Figure 3 c). A socket or fossa formed by the concave margins of adjacent basals accommodates the central and largest peg, while a small, shallow, oblong fossa on each side of the “spoon handle” accommodates the two smaller flanking pegs ( Figure 3 d). The articulation of the centrodorsal and basals via interradial ligament bundles is almost always visible externally. The interradial pits and articular surfaces have been examined in dissociated specimens of P. wyvilli ( Messing 2003) and P. orthotriremis .

The first four species described below ( P. cubensis , P. wyvilli , P. amenozoume and P. laticonulus ) have ten columns of cirrus sockets, two per radial area. The following three ( P. telo , P. c o n i f e r and P. o r t h o t r i re m i s) have 15 columns of cirrus sockets, three in each radial area.

Figures

FIGURE 3. Adoral view of centrodorsal cavity of (a) Atelecrinus balanoides PH Carpenter showing shallow interradial depressions, and (c) Paratelecrinus orthotriremis n. sp. showing interradial buttresses and deep pits. Aboral view of basal ring of (b) At. balanoides, showing central, shallow, flat depression on each basal, and (d) P. orthotriremis showing central spoonshaped fossa on each basal. Arrows indicate suture of basal with radial ossicle. R = radial ossicle. Scale bars (a – d) 0.5 mm.

FIGURE 9. Paratelecrinus cubensis (PH Carpenter). a – c. Centrodorsal and ray bases in lateral view. a. USNM E 42683. b. USNM E 42695. c. USNM E 42693. d. Two middle cirrals (upper) and tips of two cirri (middle, lower), USNM E 42693. Scale bars: lower (a – c), upper (d) both 1 mm.

FIGURE 13. Centrodorsal and ray bases in lateral view. a. Paratelecrinus laticonulus new species, holotype, MNHN IE- 2012 - 845. b. Paratelecrinus telo new species, holotype, MNHN IE- 2012 - 846. Scale bars: 1 mm.