Cenolia amezianeae, Messing, 2003

Messing, Charles G., 2003, Three new species of Comasteridae (Echinodermata, Crinoidea) from the tropical western Pacific, Zoosystema 25 (1), pp. 149-162 : 158-161

Cenolia amezianeae n. sp.

( Fig. 3 )

HOLOTYPE.— South New Caledonia. CHALCAL 2, stn CH05, 24°44’S, 168°08’E, 223 m, 27.X.1986 ( MNHN EcCh 191).

PARATYPES.— South New Caledonia. CHALCAL 2, stn CH05, 24°44’S, 168°08’E, 223 m, 27.X.1986 ( MNHN EcCh 192, 1).

Vanuatu. MUSORSTOM 8, stn CP970, 20°19’S, 169°53’E, 252-310 m, 21.IX.1994 ( MNHN EcCs 10235) ; stn CP1018, 17°53’S, 168°25’E, 300-301 m, 27.IX.1994 ( MNHN EcCs 10236, 1) .

ETYMOLOGY. — Named for Nadia Améziane, Curator of Echinoderms at the Muséum national d’Histoire naturelle, Paris, who has contributed substantially to our understanding of crinoid systematics and through whose good offices this collection was made available for study.

DISTRIBUTION. — Known only from off southern New Caledonia and Vanuatu in 223 to 300 m. C. amezianeae n. sp. occurs in more tropical waters than other Cenolia , but the gap between its southernmost record and the northernmost previous records is only a few degrees of latitude. Rowe & Gates (1995) recorded Cenolia spanoschistum (H. L. Clark, 1916) and C. glebosus Rowe, Hoggett, Birtles & Vail, 1986 , from southern Queensland; McKnight (1977) record- ed C. trichoptera (Müller, 1846) (probably C. spanoschistum according to Rowe et al. 1986) from Norfolk Island in 310 m.

DIAGNOSIS.— A species of Cenolia with stout cirri of up to 17 short segments; distal cirrals each bearing a transverse aboral ridge; up to 20 arms; pinnule combs occurring as far as P 8 to P 19, though one or two more proximal pinnules may lack a comb, and with numerous chiefly rod-shaped calcareous nodules on anal interambulacral area, along ambulacra of proximal arms and, sparsely, along genital pinnule ambulacra.

DESCRIPTION

Centrodorsal discoidal, usually with small, triangular, orally-directed interradial processes, 7.9- 10.3 mm across; D/H 3.4-4.1. Polar area with faint interradial swellings radiating from around shallow central depression. Apical margins of cirrus sockets project above polar area in one specimen.

Cirri XXXII-XLI, 14-17, up to 15.6 mm long, in crowded double marginal row. c1 short; following segments increasing in length to c5-6, which have L/ W 1.1 -1.4; following segments progressively shorter, becoming as wide as long by c7-8 and shorter thereafter. c6-7 with distal aboral margin thickened, appearing rounded triangular in lateral view, increasing slightly in strength and moving to middle of segment in side view on distal cirrals, becoming a sharp, transverse ridge on 1-2 cirrals preceding penultimate on some cirri. Penultimate cirral smaller than preceding; opposing spine weak or distinct, conical or rounded, occasionally transversely chisel-shaped. Claw longer than preceding segment; tip bluntly rounded.

Radials completely hidden by centrodorsal or just visible in interradial angles. IBr2 short, aborally flattened; Ibr 1 very short, oblong, united laterally, partly hidden by centrodorsal; Ibr 2 (axil) triangular or with very short diverging lateral margins, apposed or just separated laterally, with W/L 2.2-2.3. IIBr4(3+4) present on at least some rays of all specimens (one IIBr2 on MNHN EcCh 192). IIbr 1 short, oblong, united interiorly; W/L 3.3-3.4. IIbr 2 triangular (longer exteriorly), with a strong, distolateral, alternating articular tubercle; W/L 3.0-3.9. IIbr 3+4 pentagonal with slightly diverging lateral margins and W/L 1.5-1.75; each ossicle with a distinct transverse groove across the aboral surface. Specimen MNHN EcCs 10235 bearing six rays: four rays normal; two remaining rays with short IBr2 crowded together and with adjacent margins closely united and irregular.

Arms 14-20, mostly broken. (Arm numbers in specimens with rays broken at their bases are estimated by comparing the diameters of terminal remaining ossicles with those of IIbr 2 and br 2). Specimen MNHN EcCh 192 with an almost intact posterior arm (ray length 85 mm); its longest anterior ray broken at 98 mm. Proximal several brachials with strong, rounded, alternating articular swellings. br 1 oblong or weakly cuneate and longer exteriorly, interiorly united proximally (adjacent interior distolateral margins diverging from each other so that br 2 are separated interiorly), with W/L 2.3-2.7; br 2 longer exteriorly, with W/L 3.0-3.7; br 3+4 oblong, with W/L 2.0-2.5 and diameter 1.9-2.6 mm (on arms arising from IBr2, W/L 3.2; diameter 2.8-3.1 mm); br 3 with a shallow groove running transversely across the aboral surface; brr 5-6 oblong, with W/L 2.3-2.8. Following brachials becoming strongly cuneate, slightly wider than arm base, and almost triangular by br 9, with W/L 2.7; brachials brr 8-10 and following with thickened distal aboral margins. Middle brachials triangular with strongly thickened and very finely spinulose distal aboral margins; W/L 2.3-2.7. Distal brachials triangular or strongly cuneate with distal aboral margins finely spinose; thickening of distal aboral margins reduced beyond mid-arm and disappearing distally.

First arm syzygy at br 3+4; second chiefly from br 11+12 to br 14+15 (rarely br 7+8 to br 17+18); following interval chiefly 4-6 muscular articulations (rarely 3, 7, 9).

P II of up to 52 segments, 17.8 mm long, with 7-10 comb teeth; all pinnulars rhombic and wider than long; proximal two teeth developed as transverse filled arches (the transverse bars of Rowe et al. 1986); following teeth erect, confluent, separated and paired; distal three pinnulars diminishing to a blunt tip. P 1 of up to 50 segments, 17.6 mm, with 10-12 teeth; comb as in P II but with up to 4 proximal transversely oriented teeth and up to 4 terminal pinnulars tapering to a point. Several comb-bearing pinnulars in a row sometimes having the teeth on one side weaker than on the other; a single confluent tooth rarely developed on the opposite face of a pinnular bearing a normal pair, producing a bipectinate profile (these two features occurring on any oral pinnule).

P 2 of up to 34 segments, 10.3 mm, 14 teeth; comb-bearing pinnulars on this and succeeding pinnules flat and transversely broadened so that the teeth of a pair are widely separated and sometimes connected by a low narrow ridge. P 3 the shortest pinnule, bearing a gonad, of up to 26 segments, 7.8 mm, 12-15 teeth; third to sixth or seventh pinnulars of this and following pinnules strongly projecting laterally, giving proximal pinnule a strongly serrate profile on the side facing the arm tip. P 4 of up to 28 segments, 10.0 mm, 17 teeth. Following pinnules similar; combs present to between P 14 and P 19 (only to P 8 or P 9 in MNHN EcCs 10236), but one or two more proximal pinnules sometimes without comb. Middle pinnules of up to 30 segments, 8.8-11.5 mm, 13-14 teeth. Distal pinnules slender; proximal and middle segments with distal spinose rim; no strong lateral projections; pinnulars following the third longer than wide, with L/W up to 1.6.

Anus central; mouth marginal; numerous chiefly rod-shaped calcareous nodules on large inflated anal interambulacral area, along ambulacra of proximal arms and with a few along ambulacra of genital pinnules. Nodules also round, irregular, club-shaped or slender conical, and sometimes concentrated on anal tube.

DISCUSSION

Cenolia amezianeae n. sp. shares with C. spanoschistum transverse aboral ridges (or bars, Rowe et al. 1986) on the distal cirrals and no more than 20 arms. However, C. spanoschistum is apparently a smaller, less robust species with a centrodorsal reaching only 5 mm across (A. H. Clark 1931). Specimens with centrodorsals 3-4 mm across ( AM J11075 , TAS 212) have mature gonads, 20 arms, ray length 40-70 mm, and longest cirral (c4) with L/W up to 3.0. Unlike C. amezianeae n. sp., the brachitaxes in C. spanoschistum (and its synonym C. novaezelandiae (A. H. Clark, 1918)) are smooth and lack both alternating articular tubercles and transverse grooves.

The holotype of Cenolia benhami (A. H. Clark, 1916) ( USNM 38684) has a large centrodorsal (9.5 mm across) similar to that of C. amezianeae n. sp., but has LXVII cirri up to 23 mm long with 24-27 segments. Although it has more arms (28) than C. amezianeae n. sp., the ossicles of the brachitaxes are proportionally more elongated (a feature expected of smaller specimens); W/L of IIbr 3+4 is 1.4 in C. benhami and 1.8 in C. amezianeae n. sp. Brachitaxes ossicles are smoothly rounded as in C. spanoschistum . Also unlike C. amezianeae n. sp., the distal cirrals in C. benhami bear a curved transverse aboral ridge (that may appear weakly forked in aboral view) or tubercle. The opposing spine is conical or weak.

Cenolia tasmaniae (A. H. Clark, 1918) differs from C. amezianeae n. sp. in having more arms (up to 37) at a smaller size; distal cirrals with a small pointed aboral tubercle or rounded hump; brachitaxes without alternating articular tubercles or transverse grooves, and combs only to P 2 or P 3. A. H. Clark (1931) refers to brachitaxes ossicles as everted and finely spinous in C. tasmaniae . Rowe et al. (1986) note that small spines (perhaps similar to the rods in C. amezianeae n. sp.?) usually occur around the anal cone. However, AM J14791 , a specimen of C. tasmaniae similar in size to the holotype of that species (centrodorsal diameter 4.0 mm; cirrus length 9.0 mm), has smooth brachitaxes and a naked disk.

Cenolia trichoptera and C. glebosus both bear up to 40 arms. The former has combs as far as P 3 with 6-27 teeth consisting chiefly of filled arches (= transverse bars; see Messing 2001: fig. 5d), sometimes with some distal paired teeth. A large sexually mature specimen ( AM J14408 ; centrodorsal diameter 7.1 mm; cirrus length 13.0 mm; 36 arms; ray length 125 mm) has smooth brachitaxes with weak alternating articular tubercles on the exterior sides of the IIBr series and on the articulation between br 2 and br 3. The comb-bearing pinnulars are not as wide and the projections on the proximal pinnulars are not as strong as in C. amezianeae n. sp. C. glebosus differs from all other Cenolia in having hemispherical or globular reticulate calcareous nodules on the disk.

Figures

FIG. 3. — Cenolia amezianeae n. sp.; A, cirrus (MNHN EcCh 192); B, cirrus tip showing transverse aboral ridges (MNHN EcCs 10236); C, P14 (comb detached and viewed obliquely to show paired teeth) (MNHN EcCh 191); D, centrodorsal margin with bases of cirri and base of one ray with proximal part of one arm (MNHN EcCh 191); E, Ph pinnule comb, oblique aboral view (MNHN EcCs 10235). Scale bars: A, D, 2 mm; B, C, E, 1 mm.