Tetilla sandalina Sollas 1886

Tetilla sandalina Sollas 1886, p. 179; Sollas 1888, p. 1 – 3; pl. I, figs 16 – 27; BrØndsted 1933, p. 7; Cárdenas and Rapp 2015, p. 1504 – 1505, fig. 24; Van Soest 2016, p. 323, fig. 6a – f

Description

(Figure 14 (a – b)). Sponge pear shaped, up to 4.5 cm height and 3 cm in width. Surface even, slightly setose. The consistency is rather soft and elastic. Single conical osculum slightly displaced to the side from the summit. Numerous short papillae, represented by relatively thick bundles of spicules of main skeleton, protrude out from the base of the body (absent in juvenile forms). Colour light brown. Five specimens examined.

Skeleton

Skeleton of radially spiral structure. Cortex absent.

Spicules

(Figure 14 (c – g)). Large oxea, usually with unequal ends, dimensions: 1172 – 2545 – 3565.6 (n = 15) × 13.15 – 26.85 – 38.65 (n = 15) µm. Small oxea, slightly fusiform, with equal ends, dimensions: 567.25 – 734.2 – 990 (n = 15) × 10.1 – 16.3 – 22 (n = 15) µm. Sagittal protriaenes, rhabdome length: 1002 – 1821.3 – 3361.5 (n = 15) × 2.1 – 3.8 – 7.8 (n = 15); length of paired cladomes: 21.6 – 33.8 – 77.1 (n = 15) µm; unpaired cladome length: 64.5 – 115.9 – 223 (n = 15) µm. Raphides, dimensions: 206 – 299 – 370 (n = 10) × 1 – 2 µm. Sigmas centrotylote, spined, dimensions: 9.5 – 11.9 – 13.6 (n = 10) µm.

Distribution

Azores, off Labrador, and the Kara, Laptev (st. A-102, L-9, O-22) and East Siberian seas (A- 31). Depth range: 33 – 1828.

Remarks

All studied samples fit well with the species description presented in the monographs of Sollas (1886, 1888)), except for the dimensions and morphology of microscleres (sigmas). The latter, in our case, were characterised by a distinctly pronounced tyle on the shaft and relatively smaller sizes in general. The same distinctions from the original description were mentioned by BrØndsted (1933) and Van Soest (2016), who examined specimens obtained from the Labrador and Kara seas, respectively.

Another discrepancy concerns the distinctions in the depth distributions of the Arctic specimens (33 – 314 m) on the one hand and those collected in the Azores (1742 – 1818 m) on the other. However, since the phenomenon of equatorial submergence has frequently been observed in animals of higher latitudes (Ekman 1953), the aforementioned differences can be neglected. On the contrary, minor but persistent morphological differences may serve for the delimitation of the Arctic and Atlantic forms as separate species, but this requires the analysis of the additional materials.