Atelecrinidae

Messing, Charles G., 2013, A revision of the genus Atelecrinus PH Carpenter (Echinodermata: Crinoidea), Zootaxa 3681 (1), pp. 1-43 : 39

Atelecrinidae species A

Figure 17

Material examined. Solomon Islands: MNHN IE- 2007-7715, SALOMON 1 cruise, CP-1764, 08°36.6'S, 160°07.4'E, 1327–1598 m, 27 Sep 2001 (1 spec.).

Description. Centrodorsal tapering from base; height 4.3 mm; basal diameter 3.6; HD 1.2; apex rounded conical, almost smooth, without obsolete sockets; interradial ridge a low broad swelling reaching at least to top of basalmost cirrus socket; midradial margin shallow concave; interradial margin slightly projecting and convex; centrodorsal/basal suture distinct with trace of interradial slit-like gap. Cirri XXX, in 10 columns, 3 per column; none retained. Externally visible portion of basals gently swollen interradially, forming a complete circlet of almost uniform height. Radials short, with diverging lateral margins, just separating adjacent Ibr1; WL 3.9; radial profile 90°. IBr2 with no lateral flanges or teeth, and separated laterally by rhombic gap. Ibr1 oblong, sides slightly converging; distal margin V-shaped; WL 1.8. Iax2 hexagonal with strongly diverging lateral margins; distal angle rounded-truncated; WL 1.0. IIbr1 slightly longer and weakly flattened exteriorly; WL 1.9. IIbr2 almost triangular, separated intereriorly by rhombic gap; WL 1.25. IIbr3+4 2.1 mm across. All rays broken at IIbr1 or IIbr3.

Remarks. The externally visible appearance of the basal circlet and centrodorsal/basal articulation make identification of this specimen to genus problematic. Unlike Paratelecrinus , this specimen lacks a distinct centrodorsal/basal gap, and the basals are not strongly arched, although the uniform height of the externally visible portion of the basal ossicles, unlike those of Atelecrinus and Adelatelecrinus species, approaches that in several Paratelecrinus species. The brachitaxes most closely resemble those of Paratelecrinus wyvilli , but this specimen differs in having better developed interradial ridges on the centrodorsal (even if only low swellings), a smooth centrodorsal apex without obsolete sockets, and fewer, obviously larger, cirrus sockets; a fully developed basalmost cirrus socket is 0.25 of midradial centrodorsal height in this specimen, but only 0.20 in P. wyvilli . Because only one specimen is available, it has not been dissociated.

Figures

FIGURE 17. Atelecrinidae species A. Centrodorsal and bases of three rays in lateral view, MNHN cat. no. IE- 2007 - 7715. Scale bar: 1 mm.