Thouarella chilensis Kükenthal, 1908

TAYLOR, M. L., CAIRNS, S. D., AGNEW, D. J. & ROGERS, A. D., 2013, <strong> A revision of the genus <em> Thouarella </ em> Gray, 1870 (Octocorallia: Primnoidae), including an illustrated dichotomous key, a new species description, and comments on <em> Plumarella </ em> Gray, 1870 and <em> Dasystenella </ em>, Versluys, 1906 </ strong>, Zootaxa 3602 (1), pp. 1-105 : 60-64

11. Thouarella chilensis Kükenthal, 1908

Figs 24 , 25

Thouarella chilensis Kükenthal, 1908: 11 ; 1912: 302–304 (incorrectly described as new), text figs 4–8, pl.11, fig. 5; 1915: 150 (key)

Thouarella (Epithouarella) chilensis Kükenthal 1919: 436 , text fig. 215; 1924: 300; Cairns & Bayer 2009: 28 (listed)

Material examined: Holotype, C1780, ZMH, Iquique , Chile, no depth, 14 cm colony.

Other material: NHM 89.5 .27.43, H.M.S. Challenger, sta. 148A, off Crozet Island , sub-Antarctic, 46˚5’S, 51˚52’E, 1005 m, 3 Jan 1874 , 1 fragment; USNM 1129149, R/ V Islas Orcadas, cruise 575, sta. 65, Candlemas Island , South Sandwich Islands, Scotia Sea , 56˚44’17”S, 26˚58’36”W, 302–375 m, 31 May 1975 ; USNM 97967, R/V Hero , cruise 715, sta. 873, Thetis Bay , Tierra del Fuego, Argentina, 54˚34’S, 65˚50’W, 118 m, 26 Oct 1971 ; USNM 97966, R/V Hero , cruise 715, sta. 873, Thetis Bay , Tierra del Fuego, Argentina, 54˚34’S, 65˚50’W, 119 m, 26 Oct 1971 , 2 colonies (8.5 cm, 9 cm); USNM 1099387, R/ V Lawrence M. Gould, cruise LMG06–05, sta. 2, off Isla Grande de Tierra del Fuego, Argentina, South Atlantic Ocean, 53˚47’S, 64˚53’W, 120 m, 15 May 2006 , 3 small fragments; USNM 98283, R/ V Eltanin, cruise 11, sta. 974, north of Cape San Diego , Tierra del Fuego, Argentina, South Atlantic Ocean, 53˚33’S, 64˚56’W, 119–124 m, 12 Feb 1964 , 7 colonies; USNM 97965, R/V Hero , cruise 715, sta. 870, north of Islas de los Estados, Argentina, 54˚34’S, 64˚00’W, 84 m, 24 Oct 1971 ; MNHN, MD 42 , sta. 5, CP 30, Williams Bank, SE Indian Ocean, 53°18’S, 73°19’E, 250 m, 15 Jan 1983 ; SMF, EPOS 3 , sta. 290, AT 24, Cape Norvegia, Weddell Sea, Antarctica, 71°05.9’S, 12°34’W, 522–531 m, 19 Feb 1985 ; ZMH, R/ V W. Herwig, sta. 278, Patagonian Shelf, SW Atlantic, 40˚57’S, 56˚52’W, 200 m, 21 Jun 1966 ; ZMH, R/ V W. Herwig, sta. 142, Patagonian Shelf, SW Atlantic, 42˚06’S, 57˚55’W, 788– 765 m, 04 Jan 1971 ; ZMH, R/ V W. Herwig, sta. 590, Burdwood Bank, SW Atlantic, 54˚39.1’S, 61˚44.6’W, 940–960 m , 1978; MNHN, MD 24 , sta. 42, CM 59, L?na Bank, sub-Antarctic, 52°59’S, 44°22.7’E, 295–325 m, 4 Sep 1980 ; SMF, R/V W. Herwig 1971, sta. 277, 52°S, 55°20’W, 1200 m ; SMF, MD 42 , sta. 22, 1968, no location information .

Description

The holotype is a single bottlebrush branch ( Fig. 24a ), with short, 15 mm long, rigid branchlets that depart the main stem in at least 4 directions.

The polyps are isolated, upwardly inclined at 45–80°, 2.5–2.75 mm high, with a density of 11–23 per cm on branchlets, and densely placed at the branchlet tip, at 21–28 per cm ( Fig. 24b ). The polyps are modestly distally flared, stout, and have 8 longitudinal rows of body-wall scales and 6–8 scales in each abaxial row ( Fig. 24c ).

The operculars are triangular to arrow-head shaped ( Fig. 25e–g ), 415–510 µm high (average 460 µm), 200–300 µm wide (average 250 µm), with a H:W of 1.65–2.00 (average 1.8). The outer surface has granules arranged radially from the proximal central area ( Fig. 25e,f ) that develop into striations towards the distal edge whilst the inner surface bears a complex, multi-keel ( Fig. 25g ). Accessory operculars are occasionally present ( Fig. 25a–d ), approximately 225–150 µm high, 100–115 µm wide, with an average H:W of 1.7 (1.5–1.95).

The marginals are a wide triangle to lanceolate shape ( Fig. 25h–l ), 520–565 µm high (average 535 µm), 460–560 µm wide (average 510 µm), with a H:W of 0.9–1.2 (average 1).The outer surface, similar to the operculars, has granules arranged radially from the proximal central area that develop into striations towards the distal edge ( Fig. 25h,i,l ). The inner surface has a channelled multi-keel with rough edges ( Fig. 25j,k ). Sometimes the keel has lateral extensions that are visible from the outer surface. The proximal inner surface is covered with tubercles and areas lateral to the keel are often ridged/striated.

Submarginals are wider (with rounded lateral edges), and shorter than the marginals, having a modest distal point ( Fig. 25m –o ), a height around 350 µm, width around 400 µm and a H:W of 0.8,. The inner surface is tuberculate, with occasional ridges perpendicular to the distal edge. The outer surface has granules in a radial pattern that develop into striations towards the distal edge, which is similar to the marginals and the operculars.

The body-wall scales are roughly elliptical ( Fig. 25p–t ), 290–400 µm high (average 350 µm), 445–700 µm wide (average 560 µm), with a H:W of 0.4–0.8 (average 0.6). Generally, the outer surface bears peaked granules towards the central proximal area, while the rest is covered in pronounced striations that extend radially to the distal edge ( Fig. 25p,t ). Tubercles are visible at the proximal edge. The inner surface is tuberculate, with a relatively smooth band along the distal edge that often has small ridges. The proximal edge of all the above sclerites is coarsely lobate with a distal edge that is irregular to serrate (unless otherwise stated).

The coenenchymal scales are similarly shaped to body-wall scales except more circular and slightly smaller, down to 250 µm diameter ( Fig. 25u–w ).

Distribution

This species is found on the Patagonian Shelf, southern Atlantic Ocean, around the Antarctic Peninsula, and in the southern Indian Ocean, at depths between 84– 960 m.

Remarks

The holotype of T. chilensis was located in the ZMH, however, it was not marked as the holotype. The location and date of the inscription by Kükenthal (1908) match the data in the original type description as does the morphology and we therefore believe C1780 to be the holotype. This specimen was originally listed by the collector Schnehagen (possibly Capt. J. Schnehagen, although his collections were primarily from the South China Seas) as T. antarctica and was described by Kükenthal as T. chilenisis in 1908.

Some colonies are sparsely branched, similar to T. parachilensis ( Fig. 28a ). The colonies are generally a light yellow to white shade of colour.

The dense cylindrical clusters of polyps of T. chilensis were used by Kükenthal to distinguish this species from T. affinis and T. crenelata ( Kükenthal 1915; 1924). As the original diagrams and descriptions did not quantify the density of clustering there have been several specimens identified as T. chilensis in museums that have denser clusters of polyps at the branchlet tip than the holotype of T. chilensis . These are in fact a new species, T. parachilensis (described below). A sample of T. chilensis ( USNM 97966) was also incorrectly considered to be a voucher of T. antarctica by Cairns & Bayer (2009, Fig. 6g –l ).

Comparisons

The dense polyp arrangement of T. chilensis makes it easily mistaken for both T. antarctica and T. parachilensis . Marginals, submarginals and body-wall scales of T. chilensis have an ornamented distal edge with several ridges/ striations adjacent to the keel. The marginals of T. antarctica have a smoother edge that is more acutely pointed than on the marginals of T. chilensis . The polyps of the latter species also have, on average, more scales in the abaxial rows than the former. The operculars of the polyps of T. antarctica also tend to be thinner and more delicate than those of T. chilensis . The polyps of T. parachilensis are rounded and bulbous with 8–15 scales in the abaxial row whilst in contrast, polyps of T. chilensis are more squat and stout with just 6–8 abaxial scales.

The polyps of T. chilensis are very similar to those of T. crenelata , both species having similar polyp and sclerite sizes and shapes. The polyps of T. chilensis are, however, more clustered on the branchlets than those of T. crenelata , whose polyps are more evenly spaced. The polyps of T. chilensis generally have fewer scales in the abaxial row than T. crenelata and the outer surfaces of sclerites of the latter are smoother than the striated surfaces found on the scales of T. chilensis . The specimens identified in museums and the literature seen within this study suggest that polyps of T. crenelata are more rounded than those of T. chilensis , however, without having viewed the holotype of T. crenelata it is difficult to be certain.

Polyps of Thouarella chilensis have a similar number of abaxial body-wall scales (6–8) to those of T. viridis (6–7) and T. affinis (6–7). Both of the latter have a sparser polyp placement, and taller body-wall scales with a higher H:W than T. chilensis . Thouarella affinis also has flared rather than clavate polyps.

Polyps of Thouarella koellikeri have a similar number of scales in the abaxial row as those of T. chilensis . The sclerites of the former are more delicate, the polyps having thinner body-wall scales, marginals that curve away from the polyp body and have a simple keel, whereas sclerites of the latter are thicker with more ornamented marginals that have a wide, complex keel (the lateral extensions of which can sometimes be seen from an abaxial view).

Figures

FIGURE 6. Thouarella variabilis var. a typical, syntype, NHM 89.5.27.56: a) syntype, 22 cm long; b) close up of several polyps; c) close up of brooding polyps; d) lateral view of two polyps; e) stereo opercular view, NB—1 indicates submarginal scale; f) abaxial polyp view.

FIGURE 24. Thouarella chilensis, holotype, ZMH C1780: a) colony, 14 cm; b) close up of polyps; c) abaxial and lateral views of polyps; d) stereo opercular view of polyp.

FIGURE 25. Thouarella chilensis, holotype, ZMH C1780: a–c) inner and d) outer surface of accessory operculars; e,f) outer and g) inner surface of opercular scales; h,i,l) outer and j,k) inner surface of marginal scales; m) inner and n,o) outer surface of submarginal scales; p,r,t) outer and q,s) inner surface of body-wall scales; u) inner and v,w) outer surface of coenenchymal scales.

FIGURE 28. Thouarella parachilensis sp. nov, holotype, USNM 98338: a) colony, 29 cm long, 20 cm wide; b,c) close up of ‘barrel-shaped’ clusters of polyps; d) abaxial polyp view; e) stereo opercular view. Photo by SJ.