Atelecrinus balanoides

Messing, Charles G., 2013, A revision of the genus Atelecrinus PH Carpenter (Echinodermata: Crinoidea), Zootaxa 3681 (1), pp. 1-43 : 9-12

Atelecrinus balanoides PH Carpenter, 1881

Figures 4 , 5

Antedon cubensis Pourtalès, 1869: 356 (part); 1878: 214–215 (part).

Atelecrinus balanoides PH Carpenter 1881:15 –19, pl. 1, figs. 1–6; 1882: 489–491 (part); 1888:70–72, pl. 6, figs. 6–7.— Hartlaub 1912:481 –485, pl. 6, figs. 5–6, pl. 14, figs. 1, 2, 4, 6, 7.—AH Clark and AM Clark 1967: 819, 823–831.—AM Clark 1970: 49 –51 (part).

Atelecrinus balanoides form balanoides: Messing and Dearborn 1990:10 , 11, 23.

Holotype. St. Kitts and Nevis: MCZ 230, Blake 151, 17º08’21”N, 62º42’00”W, 15 Jan 1879, 668 m.

Other material examined. Gulf of Mexico: TAMU 3-0751, Alaminos 68A13-4, 25º38.4’N, 96º18.3’W, 512 m, 12 Nov 1968, WE Pequegnat, coll. (1 spec.); TAMU 0-0730, Alaminos 68A13-23, 27º35’N, 95º23’W, 732 m, 20 Nov 1968, WE Pequegnat, coll. (1); TAMU 3-0729, Alaminos 68A13-21, 27º38’N, 95º21.5’W, 512–641 m, 19 Nov 1968, WE Pequegnat, coll. (1); NSUOC CRI-494, MMS-NGOMCS sta. WC3, sample 5503-1, 27º35’13’N, 92º22’40”W, 768–781 m, 9 Jun 1985 (1); NSUOC CRI-551, MMS-NGOMCS sta. E2B, sample 4511, 28º18’58”N, 86º18’56”W, 600–625 m, 17 May 1985 (13); NSUOC CRI-542, MMS-NGOMCS sta. WC6, sample 5506, 27º42’44”N, 91º32’55”W, 543–783 m, 10 Jun 1985 (5); NSUOC CRI-555, MMS-NGOMCS sta. E2F, sample 4507, 28º01’04”N, 85º39’38”W, 629 m, 16 May 1985 (3); NSUOC CRI-545, MMS-NGOMCS sta. E2, sample 4510, 28º16’04”N, 86º12’05”W, 613–618 m, 17 May 1985 (1); NSUOC CRI-493, MMS-NGOMCS sta. WC4, sample 5505, 27º43’10”N, 92º09’14”W, 516–527 m, 10 Jun 1985 (3); NSUOC CRI 621, MMS-NGOMCS sta. WC2, sample 5504, 27º45’08”N, 92º29’08”W, 518–585 m, 9 Jun 1985 (5); NSUOC CRI-540, MMS-NGOMCS sta. E2A, sample 4502, 25º38’01”N, 86º45’44”W, 625 m, 13 May 1985 (1). Strait of Florida: MCZ 233, Blake 43, 24º08’N, 82º51’W, 1877-8, 620 m (1); MCZ 1102, Atlantis 2999 , 23°10'N, 81°29'W, 17 Mar 1938, 485– 770 m (3); USNM E19281 , Gerda 146, 24º45’N, 80º09’W, 23 Jun 1963, 659– 686 m (1); USNM E19286 , Gerda 112, 24º14’N, 82º56’W, 18 Jun 1963, 641– 686 m (1); USNM E19287 , Gerda 289, 24º11’N, 81º36’W, 3 Apr 1964, 594– 604 m (11 + 1 dissociated); USNM E19289 , Gerda 439, 24º14’N, 82º29’W, 29 Nov 1964, 566– 584 m (2); USNM E19292 , Gerda 93, 25º03’N, 79º45’W, 19 Apr 1963, 733 m (1); USNM E19293 , Gerda 861, 24º08’N, 81º36’W, 29 Aug 1967, 514– 558 m (1). Bahamas: USNM E19284 , Columbus Iselin 27, Chub Cay, 25º24’54”N, 78º05’24”W, 7 Jul 1972, 658– 666 m (2). Nicholas Channel: MCZ 1072, Atlantis 2990 , 23º15’N, 80º08’W, 14 Mar 1938, 714 m (2). Jamaica: E17834 , Pillsbury 1261, 17º13’00”N, 77º50’W, 15 Jul 1970, 595– 824 m (3). St. Kitts and Nevis: MCZ 43, Blake 150, 17º11’22”N, 62º46’W, 15 Jan 1879, 686 m (1). Montserrat: USNM E17880 , Pillsbury 946, 16º43’30”N, 61º57’W, 17 Jul 1969, 732– 832 m (1). Guadeloupe: USNM E17833 , Pillsbury 920, NW of Marie- Galante, 16º05’48”N, 61º18’42”W, 12 Jul 1969, 631– 704 m (3). St. Lucia: MCZ 229, Blake 222, 13º58’37”N, 61º04’45”W, 16 Feb 1879, 772 m (1). St. Vincent and Grenadines: USNM E42679 , JSL II 1746, York Bay, 13º09’23”N, 61º17’30”W, 25 Apr 1989, 739 m (1). Barbados: USNM E42690 , JSL II 1731, Maycock’s Bay, 13º16’17”N, 59º45’24”W, 17 Apr 1989, 838 m (1). Colombia: USNM E17876 (23), USNM E26227 (2), Pillsbury 781, W of Riohacha, 11º30’N, 73º26’30”W, 30 Jul 1968, 531– 567 m. Venezuela: USNM E17872 , Pillsbury 740, S of Orchila I., 11º13’N, 66º15’W, 23 Jul 1968, 827– 924 m (3); USNM E17877 , Pillsbury 754, N of Zamuro Point, 11º36’54”N, 68º42’W, 26 Jul 1968, 684– 1574 m (1).

Diagnosis. A species of Atelecrinus in which the centrodorsal base is usually parallel-sided; fulcral tubercles weak to moderate; basals weakly inflated interradially, forming continuations of short weak ridges on the centrodorsal, sometimes reduced to interradial triangles not contiguous midradially; radial profile usually ≤90º; axils well-separated laterally, rhombic or hexagonal with diverging lateral margins; lateral margins of proximal brachials rounded.

Description. Centrodorsal conical with sides usually parallel near base ( Figures 4 a–c), rarely tapering from base to apex ( Figure 4 d); interradial ridges short, weak; sockets in two columns per radial area of 2–4 sockets each, with weak to moderate fulcral tubercles; HD 1.2–1.7; basal diameter 1.8–3.5 mm. Cirri XIX–XLIII (chiefly XXV– XXXIII); one complete peripheral cirrus ( Figure 5 a) (others incomplete), of ~40 cirrals, ~ 65 mm long; c1 to c3–4 short; c4 or c5 squarish or longer than broad, LW 1.3–2.8; following cirrals flattened and longer than wide; c11–12 longest, LW up to 4.4 (to 5.0 on some apical cirri); middle segments slightly shorter and narrower; distal several segments tapering to straight or slightly bent claw; penultimate cirral longer than wide; claw sometimes blunt, kinked in at least one case. Apical cirri shorter, more slender and with fewer cirrals ( Figure 5 b).

Externally visible portion of basals flat or slightly chevron-shaped, slightly swollen and usually triangular interradially, laterally narrower ( Figures 4 a, c), rarely very narrow or reduced to interradial triangles and not visible midradially ( Figures 4 b, d). Radials with diverging lateral margins, WL 1.7–2.8; profile angle usually ≤90º. Ray length up to ~ 200 mm including +65-mm distal filament. Synarthrial swellings usually absent on IBr2, sometimes weak on IIbr1-2. Ibr1 oblong or almost square; distal margin slightly concave to deeply V-shaped, sometimes with distolateral corners cut away; WL 1.2–1.8. Axil (Iax2) rhombic; WL 1.0–1.25. Proximal brachials rounded, with no lateral flattening or thickening. IIbr1 with interior margin shorter than exterior; distal margin gently to deeply concave; WL 1.4–2.0. IIbr2 irregularly quadrate; WL 1.1–1.5. IIbr3+4 WL 0.9–1.3; 1.1–2.0 mm across. IIbr5 through middle brachials wedge-shaped to almost triangular; WL 1.0–2.0 ( Figure 5 c). Distal brachials long with expanded ends and a proximal transverse finely spinose ridge; LW 1.3–1.9 ( Figure 5 d). Sides of brachials along proximal portion of filament retaining indentation corresponding to pinnule articulation. Syzygies at 3+4, 6+7 (second rarely 5+6, 7+8 or 8+9), 9+10; interval between syzygies 2–4 proximally, 3–5 along mid-arm, 5–11 distally. One specimen with 3+4+5, 10+11. P1 usually on IIbr17 (rarely as early as IIbr13), of>19 segments; first segment short, second trapezoidal and narrower distally; distal segments elongated but LW only 2.1–2.8. Middle pinnule of>17 segments, the first short, second as long as wide and slightly narrower distally; following segments longer than wide; third through fifth with a spine on distal corner closest to arm; distal segments slender with expanded ends; LW to 8.0. Distal pinnule of 32 segments; second segment with spine on distal corner nearest arm; middle segments with LW 3.0, distal segments LW 4.0.

Distribution. Gulf of Mexico and Strait of Florida to Colombia and Venezuela, including the West Indies, but unknown from the Caribbean coast of Central America. Bathymetric range: 512–838 m, but varying regionally. Gulf of Mexico, Bahamas and Strait of Florida: 512–768 (possibly 783) m, with only three of 25 records definitely deeper than 700 m. Lesser Antilles: 686–838 m, with only one of nine records definitely shallower than 700 m.

Remarks. Atelecrinus balanoides differs from the other species in the genus in having typically weaker cirrus socket tubercles and, in almost all specimens, the centrodorsal with sides parallel near the base before tapering toward the apex. The two known specimens of Atelecrinus from Brazil, formerly attributed to At. balanoides , have been re-identified as At. helgae (see below), which restricts At. balanoides to the western Atlantic from the Gulf of Mexico to the north coast of South America. Four specimens (NHM 88.11.9.1, MCZ 43, 229 and 230) are labeled “ type.” One of these is the Challenger specimen from Brazil (NHM 88.11.9.1), now identified as At. helgae . However, AM Clark (in Clark and Clark 1967) followed H.L. Clark (1941) in recognizing MCZ 230 (from Blake 151) as the holotype, and this designation is followed here. Most previous references to At. balanoides incorporate either At. cubensis or At. helgae . Both are treated as separate species here. Their distinguishing features are discussed following their respective descriptions.

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 5. Atelecrinus balanoides PH Carpenter. a. Peripheral cirrus. b. Apical cirrus. c. Five middle brachials. d. Ten distal brachials. e. Articular facet of radial ossicle. Scale bars: upper left (a, b) 5 mm; upper right (c, d) 1 mm; lower left (e) 1 mm.