Paratelecrinus laticonulus, Messing, Charles G., 2013

Messing, Charles G., 2013, A revision of the genus Atelecrinus PH Carpenter (Echinodermata: Crinoidea), Zootaxa 3681 (1), pp. 1-43 : 31

Paratelecrinus laticonulus new species

Figure 13 a

Holotype. MNHN IE- 2012-845, BORDAU 2 cruise, CP-1529, SW of Fiji, 21°13'S, 174°58'E, 688–710 m, 3 June 2000.

Diagnosis. A species of Paratelecrinus with centrodorsal about as wide as tall, no interradial projections or ridges; interradial swellings of basal broad and sometimes bilobed; Ibr1 with distinctly converging lateral margins.

Description. Centrodorsal conical, short; basal diameter 4.5 mm; HD slightly <1.0; interradial margin not projecting but with very shallow U- or V-shaped notch; radial margin barely concave; apex rounded, with fine possible remnants of obsolete sockets. Cirrus sockets in 10 columns, two per radial area; adjacent columns crowded midradially, separated interradially by narrow gently convex space; no distinct interradial ridge; largest peripheral sockets 0.9 mm tall; fulcral tubercles moderately developed.

Cirri LIV, 5–6 per column; none retained.

Externally visible portion of basals almost straight rather than chevron-shaped, well separated from centrodorsal at least interradially; interradial swelling distinctly wider than high and often bilobed; lateral portions much narrower. Radials crescentic, very short; WL 6.8; profile acute, <70°.

IBr2 and proximal brachial pair with moderately developed synarthrial tubercles. Ibr1 with proximolateral corners inflated, lateral margins strongly converging, and distal angle shallow V-shaped; WL 2.3. Iax2 hexagonal with concave diverging lateral margins; distal angle almost parallel-sided and truncated; WL 1.1. Rays lost beyond at most IIbr9. IIbr1 longer exteriorly, weakly wedge-shaped, very slightly concave distally, just meeting interiorly over axil; WL 1.9. IIbr2 longer exteriorly, irregularly quadrate; WL 1.6. IIbr3+4 laterally rounded; WL 1.0–1.6; diameter 2.0– 2.3 mm. IIbr5 strongly wedge-shaped; WL 2.4. IIbr6+7 with WL 1.5. IIbr8 less strongly wedge-shaped than IIbr5; WL 2.6. Syzygies at 3+4, 6+7, 9+10.

Distribution. Known only from the type locality, SW of Fiji, in 688– 710 m.

Etymology. From latus, meaning broad or wide, and conulus, a small cone (both Latin). The conical centrodorsal is the broadest relative to its height of any Paratelecrinus species.

Remarks. Paratelecrinus laticonulus differs from all other Atelecrinidae in having the centrodorsal as wide across the base as tall and in having the interradial portions of at least some basal ossicles bilobed. The converging lateral margins of Ibr1 and extremely short externally visible portion of the radials closely resemble those of P. telo , described below. However, P. laticonulus differs as noted above, and in having sockets in only ten columns, centrodorsal with no interradial ridges, and proportionately narrower arm bases; IIbr3+4 is two-thirds as wide as the centrodorsal base in P. telo but only half as wide in P. laticonulus . The species resembles P. wyvilli , which was also collected off Fiji, in lacking an interradial centrodorsal ridge, but differs in multiple respects. In addition to the short wide centrodorsal, the basals are almost straight rather than arched, and swollen and often bilobed interradially; the IBr2 ossicles are proportionally much shorter and broader with a well-developed synarthrial tubercle; the lateral margins of Ibr1 are strongly converging instead of parallel, and the greatest width of the axil crosses the middle of the ossicle rather than its distal half.

Figures

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.