Paratelecrinus wyvilli

Messing, Charles G., 2013, A revision of the genus Atelecrinus PH Carpenter (Echinodermata: Crinoidea), Zootaxa 3681 (1), pp. 1-43 : 26-29

Paratelecrinus wyvilli ( PH Carpenter, 1882)

Figure 11

Atelecrinus wyvilli PH Carpenter 1882:492.—AH Clark and AM Clark, 1967:819, 820–823 (part). Atelecrinus wyvillii : PH Carpenter 1888:72 –73, pl. 6, figs. 4–5.

Atelecrinus wyvillei : AH Clark 1912:153.

Holotype. NHM 88.11.9.2, Challenger 174C, near Kandavu, Fiji, ~ 19º06’S, 178º18’E, depth uncertain (1116 m), 3 Aug 1874.

Other material examined. Philippines: MNHN IE- 2009-6746, ESTASE II cruise, CP-5, S of Mindanao, 04º59’N, 125º41’E, 1 Dec 1984, 1190 m (1 spec. dissociated for SEM). Solomon Islands: MNHN IE- 2007-7714, SALOMON 1 cruise, CP-1807, E of Guadalcanal I., 09°42.2'S, 160°52.8'E, 1077–1135 m, 2 Oct 2001 (1); MNHN IE- 2012-849, SALOMON 1 cruise, CP-2197, S of Santa Isabel I., 08°24'S, 159°22'E, 897–1057 m, 24 Oct 2004 (1); MNHN IE- 2009-9000, SALOMON 1 cruise, CP-2231, NW of Choiseul I., 06°25'S, 156°21'E, 1083–1100 m, 29 Oct 2004 (1). Japan: Tansei-maru cruise KT-08-03, sta. SM-01-02, Shima Spur, off Shima, Mie Prefecture, 34°00.72’N, 136°53.28’E to 34°01.55’N, 136°52.98’E, 781–789 m, 4 Mar 2008, 3-m ORI beam trawl, T. Oji, coll. (2). LOCATION? MNHN cat. no.? probably Solomon Is. or Fiji (1).

Diagnostic features. A species of Paratelecrinus with centrodorsal having 10 columns of sockets, basal interradial ridges weak or absent and interradial margin flat or slightly indented. Externally visible portion of basals shallow chevron-shaped; Iax2 rhombic.

Description of the holotype ( Figure 11a ). Centrodorsal conical, slightly wider just above base; basal diameter 3.1 mm; HD 1.16; no basal interradial ridges; interradial margin slightly concave. Cirrus sockets in 10 wellseparated columns of 4–5 sockets each, with functional sockets reaching the aboral pole. Cirri ~XLV, none retained.

Basals gently arched, of almost uniform height, not swollen interradially, forming a low complete ring widely separated interradially from centrodorsal. Radials short; WL 3.9; radial profile ~90°. IBr2 and IIbr1–2 with no synarthrial swelling. Ibr1 oblong, straight-sided, with distolateral corners cut away and distal margin deeply Vshaped; WL 1.9. Iax2 rhombic, lateral margins slightly sinuous; WL 1.0. IIbr1 longer exteriorly, distal margin shallowly concave, exterior margins slightly ridged; WL 2.0. IIbr2 longer exteriorly, irregularly quadrate; WL 1.2. IIbr3+4 1.4 mm across; WL 1.0. Following few remaining brachials wedge-shaped. Disk almost naked; mouth somewhat eccentric.

Description of other specimens. Centrodorsal conical, slightly wider just above base, or base barely straightsided; basal diameter 2.9–3.7 mm; 3.8–4.9 mm high; HD 1.3; apex almost covered with obsolete sockets or with five fine ridges derived from apical sockets; socket tubercles moderate to strong, sometimes slightly hooked; interradial ridge virtually absent or low and not reaching top of basalmost socket; midradial margin gently concave; interradial margin flat or slightly concave, projecting or not. Cirri LIV –LX in 10 columns, 5–7 sockets per column; none retained; smallest specimen XLI with 4–5 functional sockets per column plus 1–2 distinct obsolete sockets. Externally visible portion of basals gently arched or shallow chevron-shaped; interradial portion triangular, weakly inflated or flat; laterally parallel-sided and only slightly thinner with slightly enlarged ends; centrodorsal/basal suture distinct with interradial slit-like gap, longer from end to end than in Adelatelecrinus vallatus . Radials short, separating Ibr1; WL 3.9–4.0, 2.4 in smallest specimen; radial profile 90–110°. IBr2 separated laterally by distinct gap, and with moderately developed synarthrial tubercle. Ibr1 roughly oblong with thin, slightly sinuous lateral edge and V-shaped distal margin; WL 1.9. Iax2 rhombic or hexagonal with strongly diverging lateral margins; distal angle truncated; WL 1.0.

A larger specimen ( MNHN IE- 2009-9001) with small, thin, convex, ear-like projection distolaterally on Ibr1, laterally on Iax2, and continued as thin low exterior ridge on IIbr1–2. IIbr1 much longer exteriorly; WL 1.8–1.9. IIbr2 pentagonal or irregularly quadrate; interior gap present; WL1.2–1.4. IIbr3+4 with WL 1.2–1.7; diameter 1.7–2.4 mm. One arm of MNHN IE- 2009-9000 with IIbr3 triangular, longer interiorly, not hypozygal; WL 2.0; followed by IIbr4+5. Normal IIbr5 almost triangular; WL 1.9. All other syzygies 6+7, 9+10.

A small slender specimen ( MNHN cat. no.?) ( Figure 11 b) attributed to this species has centrodorsal diameter 2.4 mm, height 3.1 mm and HD 1.3, and retains a small, flat, stellate apex 0.6 mm across, with trace of central lumen—the remnant of the articulation with the postlarval stalk ( Figure 11 c). Interradial base of centrodorsal slightly swollen and projecting. Cirri ~XXXV, in columns of 3 and 4 in each radial area, with well developed articular tubercles, almost reaching apex (difficult to determine if apicalmost sockets are functional). Cirri detached, in fragments; longest at least 45 mm, 20 segments; c1–c2 short; c3 with LW 2.8; following cirrals somewhat compressed, with expanded distal ends; longest middle cirrals with LW>6.0; cirrals shorter distally but remaining longer than wide to near tip; antepenultimate cirral squarish with slight distal aboral expansion; penultimate cirral shorter than wide, with small blunt opposing spine; claw short, hooked ( Figure 11 d). Externally visible portion of basals strongly arched, chevron shaped, with lateral ends slightly enlarged, and separated from interradial margin of centrodorsal by wide gap. Radials with straight sides and broadly shallow U-shaped distal margin; WL 2.2; radial profile 50º. Ray length reconstructed from fragments> 150 mm (without distal apinnulate portion). IBr2 elongated, narrow, separated laterally by lateral margins of radial articular facets. Ibr1 oblong, concave distally; WL 1.2. Iax2 narrow, shield shaped, longer than wide; LW 1.7. Arms well separated; IIbr1 squarish; WL 1.25. IIbr2 longer than wide; proximal angle gently convex; WL 0.9. IIbr3+4 elongated, 1.2 mm across; WL 0.7. Following brachials becoming more elongated with expanded ends, with LW>6.0 distally. Syzygies at 3+4, 6+7, 9+10, 12+13; following syzygial pairs chiefly separated by one (sometimes 2) muscular articulation. P1 on IIbr17. Pinnulars except first longer than broad; LW up to at least 8.0.

Two much larger specimens (Tansei-maru KT-08-03) differ in some respects from those described above and are treated as P. wyvilli only tentatively. One has been dissociated for SEM; the other is described as follows: centrodorsal conical, tapering from base; basal diameter 4.2 mm; height 6.0 mm; HD 1.4; apex with five low interradial glassy ridges (remnants of apicalmost sockets); socket tubercles moderate to strong; interradial ridge a low, short swelling, not reaching level of lumen of basalmost socket; midradial margin of centrodorsal shallow concave with tiny midradial triangular projection; interradial margin concave. Centrodorsal/basal suture distinct, with an interradial slit-like gap. Cirri LXVI, longest remaining of 40 segments, 63 mm long, in 10 columns of 6–7 sockets each; two radial areas with 1 basal socket midradially between columns; c1–3 short; c4 of peripheral cirrus with LW 0.9 (1.3 on apical cirrus); following cirrals increasing in length and becoming compressed; c9–19 about equally long, with LW 3.1; cirrals gradually shorter distally; distalmost ~12 cirrals tapering; antepenultimate cirral with LW 1.7; penultimate still longer than wide; no opposing spine; terminal claw gently hooked.

Externally visible portion of basals swollen interradially, somewhat thinner laterally and parallel-sided with slightly wider ends. Large central fossa in aboral surface of basals with shallow, indistinct, circular or doughnutshaped depression; central recess flanked by two small depressions; only one interior curved projection remaining; no trace of calcareous plug. Radials very short, separating Ibr1; WL 3.9; profile ~100°. IBr2 separated laterally by large gaps, and with strong synarthrial tubercle. Ibr1 oblong with thin sinuous lateral margins, deeply V-shaped distal margin and fine diagonal distolateral raised line. Iax2 hexagonal with strongly diverging lateral margins (can also be described as rhombic with sinuous proximolateral margins); distal angle truncated; WL 1.0. IIbr1 longer and thickened exteriorly; WL 1.9. IIbr2 irregularly quadrate with interior gap; WL 1.3. IIbr3+4 2.6 mm across; WL 1.2. IIbr5 almost triangular; WL 2.2. Following sygyzgies at 6+7, 9+10.

Remaining undissociated ray bases of second specimen with syzygies beyond 3+4 at 6+7, 9+10 (3 arms), 6+7, 9+10, 13+14 (1), 6+7, 12+13 (2) and 7+8, 12+13 (2).

Distribution. Fiji; Solomon Islands; S of Mindanao, Philippines; central Japan; in (781?) 789–1190 m. Although PH Carpenter (1888) gave the depth of Challenger station 174C as 610 fathoms (1116 m), AH Clark (in Clark and Clark 1967) listed 411, 1115 or 384 m (225, 610 and 210 fathoms) for this station. However, his first depth is likely an error for the 255 fathoms of station 174B, and the third is the depth of dredge station 174D ( Murray 1895).

Remarks. As mentioned above, the uncalcified integumentary gap between the centrodorsal and basals, and the elaborate aboral basal articular facet, indicate that this species belongs in Paratelecrinus (see Messing 2003). Several specimens previously attributed to P. wyvilli are either Adelatelecrinus sulcatus [ Siboga 85 (NCB), USNM 36220, and Deutschen Tiefsee-Expedition 210 (ZSM)] ( Clark & Clark 1967, AM Clark 1977) or a new species ( Kogo 1998) described below. MNHN IE-2009-6746, although dissociated before the Solomon Islands specimens were examined, exhibits several characters typical of P. wyvilli and is retained in this species: the centrodorsal tapers from the base, bears sockets to the apex and only the slightest trace of any interradial basal swelling, and has aboral basal articular facets characteristic of Paratelecrinus . MNHN IE-2007-7714 and IE-2009-9000 from the Solomon Islands differ from the holotype chiefly in having a narrower slit-like interradial gap between the centrodorsal and basals, and thin ridges instead of distinct obsolete sockets at the centrodorsal apex. MNHN IE- 2009-9001 also has a centrodorsal/basal slit unlike the holotype, but also differs in having distinct (although still weak) interradial ridges at the centrodorsal base, and thin lateral projections on proximal ray ossicles. This specimen is larger (centrodorsal diameter 3.7 mm) than most other P. wyvilli (max. 3.1 mm), so the features may be size-related.

The two large specimens from Japan are only tentatively treated as P. wyvilli . The general appearance of the centrodorsal and the shapes of the ray base ossicles agree with P. wyvilli , but the interradial portion of the basals is swollen and the ray bases exhibit strong synarthrial tubercles. As in the Solomon Islands specimens, but unlike the holotype, the interradial gap between the centrodorsal and basals is only a slit. Two additional features suggest that these specimens may not belong in Paratelecrinus : 1) the central fossa in the aboral surface of the basal exhibits only a trace of a spoon-shaped articulation, although there are two pairs of pits on either side (as in P. orthotriremis ), and 2) the cirri taper to a point without an opposing spine. However, the complex basal articulation and the cirri with an opposing spine have not been described in all species attributed here to Paratelecrinus (because too few specimens are available in most cases for dissociation, and because complete cirri are rarely retained), so either or both may prove not diagnostic for the genus when additional specimens are collected. Cirri with an opposing aboral spine have only been described so far in P. c u b e n s i s and P. orthotriremis (see below). Also, the reduced centrodorsal/basal gap, strong synarthrial tubercles and limited sculpturing of the aboral basal articulation may perhaps be associated with the much greater size (and age?) of the specimens from Japan.

Figures

FIGURE 11. a. Paratelecrinus wyvilli (PH Carpenter). a. NHM 88.11. 9.2 (holotype), centrodorsal and ray bases in lateral view. b – d. MNHN? (Solomon Is. or Fiji). b. Centrodorsal and ray bases in lateral view (NOTE: Strong vertical shadows due to enhanced contrast to clarify skeletal details; the specimen is uniformly white). c. Pentagonal aboral apex of centrodorsal. d. Cirrus tip. Scale bars: (b, d) 1 mm. The holotype of P. wyvilli was inadvertently drawn without a scale bar; however, the diameter across the base of the centrodorsal was measured as 3.1 mm when the illustration was made. The pentagonal centrodorsal apex in c is 0.6 mm across.