Crateromorpha (Neopsacas) variata Tabachnick, 2002

Menshenina, Larisa L., Tabachnick, Konstantin R. & Janussen, Dorte, 2007, Revision of the subgenus Neopsacas (Hexactinellida, Rossellidae, Crateromorpha) with the description of new species and subspecies, Zootaxa 1463, pp. 55-68 : 56-60

Crateromorpha (Neopsacas) variata Tabachnick, 2002 ( Fig. 1 , 2 ; Tab. 1 )

Synonymy

Crateromorpha (Neopsacas) variata Tabachnick, 2002: 1481 .

Material examined

Holotype: IORAS 5/2/404, R.V. ‘Academic Kurchatov’, 6 voyage, sta. 444, 5.10.1969, 40° 35.3’–36.2’ N, 29° 29.5’–29.4’ W (Mid-Atlantic Ridge), depth 2780- 2500 m.

Paratypes: IORAS 5/2/403, ibid.; IORAS 5/2/479 – R.V. ‘Academic Kurchatov’, 6 voyage, sta. 432, 40° 28.8’–28.5’ N, 29° 33.0’–32.5’ W, depth 2780–2900 m.

Additional studied material: IORAS 5/2/3119, R.V. ‘Academic Mstislav Keldysh’, 43 voyage, sta. 3988, submersible ‘Mir’, 44° 57.40’ N, 28° 0.90’ W, depth 2800 m. IORAS 5/2/3114, ibid. (Mid-Atlantic Ridge).

C. variata C. variata C. variata C. variata C. variata (Holotype, (Paratype, (Paratype, (Non type, (Non type, IORAS 5/2/404) IORAS 5/2/403) IORAS 5/2/479) IORAS 5/2/3114) IORAS 5/2/3119) Description

Body: Types have previously been described by Tabachnick (2002). The newly found specimen (5/2/ 3119) has the shape of a champagne-glass, lower part of the tubular peduncle broken. The body is 80 mm long, 80 mm in diameter with large atrial cavity, 60 mm deep, 60 mm in diameter in the upper part of the body. Walls are about 10 mm in thickness with many deep subdermal cavities 0.5–6 mm in diameter and canals beginning from the atrial surface. The dermal openings are covered by dermal layer made of regularly orientated dermal pentactins with square meshes between their tangential rays; atrial openings seems not to be covered by an atrial lattice. The peduncle is broken, its remnant is tubular, 50 mm long, 4 mm in diameter. The 5/ 2/3114 specimen is a small fragment 3–4 mm in thickness, it is likely a fragment from the margin of specimen 5/2/3119.

Spicules: Choanosomal spicules and the spicules of the peduncle are diactins, the latter are fused by numerous synapticula while other forms: triactins, paratetractins and pentactins could be rarely found anong the former. Investigations of new specimens (5/2/3119; 5/2/3114) allow us to revise the previous interpretation by Tabachnick (2002) of the construction of dermal/atrial skeleton. Dermalia and atrialia consist of similar spicules with similar spicule size. Dermalia and atrialia are spicules with rough rays and rounded outer ends. They are pentactins and derivatives with reduced rays, and commonly have a short proximal (or distal) ray; diactins are common, and rare hexactins may be also found. The pentactins form a layer over the subdermal cavities, but the dermal and atrial spicules do not seem to construct a continuous net, they do not overlap by their tangential rays. Hypodermal or hypoatrial pentactins are more or less regularly situated. The tangential rays of hypodermal pentactins are 0.038–0.448 mm long, the proximal ray is 0.053–0.304 mm long, their diameter is 0.01–0.05 mm. The ray of dermal diactin is 0.046–0.091/ 0.002–0.005 mm, usually these spicules have four rudimental tubercles in the middle. Atrial spicules are very similar to dermal ones. The atrial pentactins have tangential rays 0.068–0.388 mm long, distal ray 0.053–0.152 mm long, diameter is 0.008–0.03 mm. Atrial diactins have rays 0.018–0.167/ 0.004–0.006 mm. Hypodermal and hypoatrial pentactins have spines near the spicule centre. Tangential rays of dermal pentactins are 0.175–0.456 mm long, proximal ray is 0.091–1.041 mm long, diameter is 0.020–0.040 mm. Hypoatrial pentactins have tangential rays 0.076–0.646 mm long, distal ray is 0.038–1.011 mm long. Large numbers of hexactins similar to hypodermal/hypoatrial spicules were found as oscularia marginalia, which can be attributed to atrial surface rather than to dermal one in two of the newly found specimens (5/2/3119; 5/2/3114). The ray directed outside the body of these hexactins is 0.061–0.494 mm long, tangential rays are 0.099–0.243 mm long, the ray directed inside the body is 0.395–1.406 mm long, their diameters are about 0.015 mm.

The microscleres were described quite correctly before ( Tabachnick, 2002) but new findings allow addition the previous data. The large discohexactins and their derivatives have rays 0.058–0.115/ 0.004–0.007 mm. The small discohexactins and their derivatives have rays measuring 0.025–0.090/ 0.002–0.004 mm. The most common hemioxyhexasters, oxyhexactins, hemionychohexasters and onychohexactins are 0.036–0.133 mm in diameter. The regular oxyhexasters with numerous secondary rays are 0.036–0.101 mm in diameter with primary rosette 0.011–0.061 mm in diameter. The regular onychohexasters/discohexasters with numerous secondary rays are 0.054–0.101 mm in diameter with primary rosette 0.011–0.025 mm in diameter.

Figures

FIGURE 1. Crateromorpha (Neopsacas) variata Tabachnick, 2002, specimen IORAS 5 / 2 / 3119.: A, view from above. B, side view. Scale 40 mm. C, dermal surface with dermal net covering the subdermal cavities. Scale 5 mm. D, oxyhexasters and oxyhemihexasters, E, irregular diactin, F, onycho-discohexaster. 10 µm.

FIGURE 2. Crateromorpha (Neopsacas) variata Tabachnick, 2002, spicules: A – B, dermal pentactins. C – D, dermal diactins. E – F, atrial pentactins. G, atrial stauractin. H – J, atrial diactins. K, hypodermal pentactin. L – M, marginal hexactins. N – P, abnormal microscleres. A – K; N – P, 5 / 2 / 404. O – P, 5 / 2 / 3119.

Tables

TABLE 1: Spicule dimensions of C. (Neopsacas) variata Tabachnick, 2002. L. length. D. diameter of spicule. d. diameter of primary rosette.

	n	avg	min	max	std	n	avg	min	max	std	n	avg	min max std	n	avg	min	max	std	n	avg	min	max std
L derm. pent. tang. ray	6	.258	.167	.312	.0 62	7	.293	.0 38	.448	.129				25	.332	.251	.395	.0 33
L derm.pent. prox. ray	1	.122	.122	.122										25	.101	.0 53	.304	.0 56
L derm. hex., para- tetrac., stauractin ray	6	.105	.0 53	.190	.0 46	12	.0 77	.0 38	.137	.0 24
L derm. diactin ray	6	.0 71	.0 46	.0 91	.0 16
L atrial pent. tang. ray	19	.174	.0 68	.319	.0 71	14	.268	.182	.388	.0 64
L atrial pent. dist. ray	3	.0 94	.0 53	.152	.0 52
L.atrial hex., para- tetrac., stauract. ray	8	.0 77	.0 41	.176	.0 42	18	.0 79	.0 45	.207	.0 35	1	.0 85	.0 85.0 85	3	.0 22	.0 14	.0 29	.0 0 7	25	.155	.0 76	.327.0 63
L atrial diactin ray	8	.103	.0 76	.167	.0 28	17	.0 81	.0 61	.167	.0 24				7	.0 24	.0 18	.0 34	.0 0 6	25	.0 75	.0 41	.107.0 21
L hypoderm. pentac. tang. ray	25	.325	.213	.441	.0 55	20	.357	.228	.456	.0 71	12	.220	.380.0 57	25	.255	.175	.357	.0 48	25	.327	.190	.441.0 50
L hypoderm. pentac. prox. ray	25	.695	.152	.897	.164	17	.675	.380	.836	.130	13	.755	.494.973.126	10	.433	.319	.532	.0 74	25	.714	.0 91	1.04.212 1
L hypoatr. pent. tang. ray	20	.213	.114	.365	.0 68	11	.348	.182	.646	.117				24	.273	.205	.365	.0 39	25	.248	.0 76	.380 0.63
L hypoatr. pent. dist. ray	20	.472	.137	.851	.191	11	.621	.365	.836	.167				25	.639	.266	1.01	.180	25	.407	.0 38	.631.106
L hypoatr. hex. ray directed outside body											25	.222	.0 61.494.144	11	.149	.0 61	.334	.116
L hypoatr. hexa. tang. ray											25	.181	.0 99.220.0 29	10	.201	.152	.243	.0 32
L hypoatr. hexa. ray directed inside body											24	.705	.395 1.40.281 6	12	.688	.403	1.36 8	.256
L large discohexactins & derivatives ray	20	.0 94	.0 77	.115	.0 0 9	20	.0 75	.0 58	.0 94	.0 11	20	.0 95	.0 85.108.0 0 7
L small discohexactins & derivatives ray	20	.0 33	.0 25	.0 38	.0 0 3	20	.0 43	.0 31	.0 58	.0 0 8	20	.0 47	.0 34.0 68.0 0 8	4	.0 36	.0 32	.0 41	.0 0 4	25	.0 71	.0 58	.0 90.0 0 8
D hemidiscohexaster	20	.0 66	.0 54	.0 94	.0 10	20	.0 89	.0 61	.133	.0 18	20	.0 80	.0 58.108.0 12	13	.0 71	.0 65	.0 86	.0 0 7	25	.0 68	.0 58	.0 83.0 0 6
d hemidiscohexaster	20	.0 15	.0 11	.0 22	.0 0 4	20	.0 17	.0 11	.0 22	.0 0 2	13	.0 18	.0 11.0 29.0 0 4	25	0.15	0.07	.0 32	.0 0 5
D oxyhexac., onycho- hexac. & derivatives	20	.0 90	.0 65	.108	.0 12	20	.0 99	.0 76	.130	.0 13	20	.0 96	.0 79.115.0 10	25	.0 88	.0 65	.104	.0 0 8	25	.0 83	.0 50	.108.0 11
D oxyhemihexaster & onychaster	20	.0 89	.0 65	.108	.0 0 9	20	.0 90	.0 72	.130	.0 14	20	.0 87	.0 65.108.0 10	25	.0 88	.0 65	.112	.0 0 9	25	.0 85	.0 65	.0 97.0 10
d oxyhemihexaster & onychaster	20	.0 16	.0 11	.0 18	.0 0 2	20	.0 15	.0 11	.0 18	.0 0 2	20	.0 15	.0 11.0 18.0 0 2	25	.0 16	.0 11	.0 22	.0 0 3	25	.0 16	.0 11	.0 20.0 0 2
D regular oxyhexaster	4	.0 52	.0 43	.0 61	.0 0 9	20	.0 53	.0 40	.101	.0 13	2	.0 58	.0 47.0 68.0 15	25	.0 60	.0 47	.0 90	.0 10	25	.0 54	.0 36	.0 72.0 0 7
d regular oxyhexaster	4	.0 16	.0 11	.0 22	.0 0 5	20	.0 18	.0 11	.0 61	.0 10	5	.0 17	.0 14.0 22.0 0 3	25	.0 18	.0 13	.0 29	.0 0 4	25	.0 16	.0 0 9	.0 22.0 0 2
D regular onychohex./ discohex.	25	.0 79	.0 54	.101	.0 12						3	.0 97	.0 90.101.0 0 6	25	.0 77	.0 65	.0 90	.0 0 7	25	.0 76	.0 61	.0 90.0 0 6
d regular onychohex./ discohex.	25	.0 18	.0 11	.0 25	.0 0 4						3	.0 18	.0 18.0 18.0 0 0	25	.0 19	.0 11	.0 25	.0 0 4	25	.0 18	.0 11	.0 22.0 0 3