Paratelecrinus Messing, 2013

Mei, Zijie, Sha, Zhongli & Sun, Shao'e, 2023, Going deeper and further: a range and depth extension for the deep-sea feather star Paratelecrinus cubensis (Carpenter, 1881) (Comatulida, Atelecrinidae), first record from the Western Pacific, ZooKeys 1184, pp. 103-113 : 103

Genus Paratelecrinus Messing, 2013

Paratelecrinus cubensis (Carpenter, 1881).

Antedon cubensis : Pourtalès 1869: 356 (in part); 1878: 214-215 (in part).

Atelecrinus cubensis Carpenter, 1881: 15-19, pl. 1 fig. 7; 1882: 491-492; 1888: 70-72. A.H. Clark 1907: 155. Hartlaub 1912: 281, 386, 484, pl. 14, figs 3, 8, 9.

Atelecrinus pourtalesi : A.H. Clark 1907: 4. H.L. Clark 1941: 13.

Atelecrinus balanoides : A.H. Clark and A.M Clark 1967: 819, 823-831 (in part).

Paratelecrinus cubensis : C.G. Messing 2013: 22-24, figs 9, 10.

Material examined.

MBM287771, 1 specimen; Western Pacific , Kocebu Guyot, R / V KeXue station FX-Dive177; 17°21′14″N, 153°08′35″E; 1294 m depth, 11 April 2018, hard substrate .

Description.

The middle and distal parts of the rays of the specimen are missing, broken off at IIbr3, IIbr6, and IIbr9 (Fig. 2 ).

Centrodorsal conical, base diameter 3.0 mm, H/D 1.3; interradial margin with U-shaped depression (Fig. 3 ). Cirrus sockets distributed in 10 columns, with strong fulcral tubercles. Cirri XL, only one complete peripheral cirrus (Fig. 4b ) 69.1 mm long and with 31 segments; c1-3 short and cirrals gradually increasing in length, with expanded distal ends; c8-c13 longest, L/W 6.7; penultimate cirral squarish, with opposing spine weak or absent, terminal claw curled (Fig. 5b ). Apical cirrus of 22 segments, 15.0 mm long; c5-c7 longest, L/W 3.4 (Fig. 4a ).

Basals form a complete ring, separated from centrodorsal by distinct ligamentous bundles, especially interradially; externally visible portion of basals swollen interradially and then narrowing laterally, with a concave lower edge interradially and an overall inverted V-shape (Fig. 6c ). Radials are very short, W/L 3.2. Lateral margin of radials clearly visible, separating adjacent brachitaxes (Fig. 6c ).

Arms 10, 2.9-8.3 mm long (Fig. 3 ). First brachitaxes and proximal rays with moderately developed synarthrial tubercles. Ibr1 rectangular, with V-shaped distal margin and thin projections on lateral margins, W/L 2.5. Iax2 rhombic, laterally margin with wing-like flange, lower edge distinctly convex, W/L 1.1. IIbr1, W/L 2.7, outer lateral margin longer and slightly curled inward (Fig. 6a ). IIbr2, W/L 1.3, irregularly square, outer lateral margin longer, distal margin wider, proximal margin V shaped, with sufficient clearance from adjacent IIbr2. IIbr3+4 longer interiorly, W/L 1.2, 1.7 mm across. Middle brachials wedge-shaped, W/L 1.8. Distal brachials wedge-shaped and longer than wide, with distal ends slightly raised, W/L 0.6 (Fig. 6b ). Syzygies at (3+4), (6+7), (9+10).

Distribution.

Previous records of P. cubensis have been only collected in the deep sea off the Bahamas and Cuba (567-892 m) ( Messing 2013). The current study is the first report of P. cubensis from Kocebu Guyot, which extends the known geographical distribution of this species to the Western Pacific Ocean (Fig. 1 ). Furthermore, the new record is the deepest known observation of P. cubensis ; at 1294 m, this observation extends the depth of this feather star beyond 1000 m.

McClain and Hardy (2010) have suggested that bathymetric gradients may impose limitations on the range of species compared to horizontal distances, and that the geographic distribution of species may be more frequent where water depths are deeper. Based on this hypothesis, the large gap in the geographic distribution of P. cubensis seems reasonable. Furthermore, biodiversity correlates with latitude, showing patterns of tropical peaks and polar declines in species richness ( Mannion et al. 2014). The collection site is consistent with the latitudinal distribution of previous records, which supports the very large geographic distribution of P. cubensis .

Figures

Figure 1. Location of the new record of Paratelecrinus cubensis a map showing the Magellan Seamounts (red dot) b map showing the collection location (green dot) and the Kocebu Guyot (red dot).

Figure 2. Paratelecrinus cubensis from Kocebu Guyot, showing the original color. The first " cirri " from the left is a broken part of a distal arm.

Figure 3. Paratelecrinus cubensis from Kocebu Guyot: Centrodorsal and ray base.

Figure 4. Paratelecrinus cubensis from Kocebu Guyot a apical cirrus b peripheral cirrus.

Figure 5. Paratelecrinus cubensis from Kocebu Guyot a tips of apical cirrus b tips of peripheral cirrus c two middle cirrals (upper) and tips of two cirri (middle, lower) (modified from Messing 2013).

Figure 6. Paratelecrinus cubensis from Kocebu Guyot a IBr and IIBr flanges b distal arm part c basals and radials.