Adelatelecrinus, Messing, Charles G., 2013

Messing, Charles G., 2013, A revision of the genus Atelecrinus PH Carpenter (Echinodermata: Crinoidea), Zootaxa 3681 (1), pp. 1-43 : 15-16

Adelatelecrinus new genus

Atelecrinus : AH Clark 1912: 152.— Hartlaub 1912:480 –481 (part).—AH Clark 1918:262, 266–268 (part).— Clark and Clark 1967:817 –819 (part).

Diagnosis. A genus of Atelecrinidae with centrodorsal hollow and thin-walled, closely joined to basal ring or slightly separated interradially by narrow gap or slit; central cavity diameter ≥0.6 of basal diameter; adoral rim of centrodorsal with 5 hollow, interradial buttresses that open adorally as deep, ring-shaped pits ( Figure 7 d). Cirrus sockets in 10 columns with moderately developed aborally-projecting lateral fulcral tubercles triangular in side view; cirri (when known) tapering to a point with no opposing spine. Externally visible portion of each basal flat or slightly arched, weakly swollen interradially if at all, with lateral portions parallel-sided or tapering, and ends contiguous midradially ( Figures 7 a, 8); sometimes reduced, triangular and separated midradially ( Figure 7 b, c). Aboral surface of basals with featureless, central depression, and with adorally curved and distally expanded pair of interior projections ( Figure 7 e). Radial cavity with delicate aboral calcareous deposit. Most proximal pinnule on IIbr15–16.

Type species. Atelecrinus sulcatus AH Clark, 1912.

Other included species. Adelatelecrinus vallatus new species.

Etymology. From the Greek adelos, meaning obscure, unknown, unseen, and the generic name Atelecrinus .

Remarks. Some specimens of species in this genus are externally indistinguishable from Atelecrinus in having a close suture between centrodorsal and basal ring ( Figures 4 , 6, 7a, c, 8). However, most exhibit a narrow interradial gap or slit between the centrodorsal and basals ( Figure 7 b) not found in Atelecrinus . Adelatelecrinus shares with Paratelecrinus (described below) distinctive deep interradial pits in the centrodorsal rim ( Figure 7 d), which separate both from Atelecrinus . However, Adelatelecrinus lacks the complex articular facet on the aboral surface of the basal ossicles characteristic of Paratelecrinus (Compare figures 3d and 7e).

Figures

FIGURE 4. Atelecrinus balanoides PH Carpenter. Centrodorsal and ray bases in lateral view. a. E 19287. b. MCZ 43. c. MCZ 230 (holotype). d. USNM E 42690. Scale bars: 1 mm.

FIGURE 7. Adelatelecrinus sulcatus (A. H. Clark). a – c. Centrodorsal and ray bases in lateral view. a. NCB V. ECH. C. 2098 (holotype). b. MNHN IE- 2007 - 7711. c. USNM 36220. d. MNHN IE- 2007 - 7710, centrodorsal and four (of five) basals partially separated from centrodorsal to reveal deep interradial pit in centrodorsal margin. e. MNHN IE- 2007 - 7710, basal ossicle, aboral view (interior processes partially crushed). Scale bars: (a – d) 1 mm; (e) 100 μm.