Tedania (Tedaniopsis) tantula Kirkpatrick 1907

Tedania (Tedaniopsis) tantula (Kirkpatrick, 1907)

(Fig. 11, Tab. 7)

Tedania tantula (Kirkpatrick, 1907): Koltun 1964: 61–62, text-fig. 13, pl. 10, fig. 20–25, 1976: 183. Van Soest 2002a: 631–632.

Synonymy:

Oceanapia tantula Kirkpatrick, 1907: 289, 1908:50, pl. 18, fig. 5, pl. 24, fig. 8. Paratedania tarantula (Kirkpatrick, 1907): Burton 1929: 441.

Not Tedania massa Ridley & Dendy, 1886: 335, 1887: 53, pl. 11, fig. 4, pl. 23, fig. 2. Tedania massa Ridley & Dendy, 1886: Burton 1932: 303–306, fig. 25 (partly).

Material. 2 sponges from station 048-1 (SMF 11853, 11854), 602.1 m, 70° 23.94' S, 8° 19.14' W, 12.01.2008.

Description. Observed samples rather fragmentary, one (SMF 11853, Fig. 11 A) a part from the middle of a sponge, about 20 mm long and 7 mm in diameter, the other (SMF 11854), about 30 mm long and up to 5 mm in diameter, representing the whole lower part of a sponge including plate-like attachment structure of about 3 mm in diameter. Fragments of tubular shape, growing erectly on hard substrate. Tubes conical, widening towards the top, internally hollow.

Skeleton (Fig. 11 B): Epidermis tough, made up of mainly strongyles and additionally tornotes. Spicules relatively tight packed with no distinct orientation, although in parts a weak pattern seems to be implied. On the inside of the sponge epidermis overlain by thick tracts of onychaetes.

Spiculation (Tab. 7): Main spicules strongyles (Fig. 11 C–D), 440 x 28 µm; relatively thick, of usual shape, slightly bowed, often with a slight kink in the outer third. Tornotes (Fig. 11 F), 396 x 10 µm straight, with distinct swellings on each end, bearing a spine on the distal side. Two kinds of onychaetes present (Fig. 11 E), distinguished by their length. These are very thin monaxonal spicules, covered by thin spines, which all point in the same direction. Larger ones 705 x 3 µm, smaller ones 110 x 2 µm.

Remarks. At present, T. (T.) tantula is not accepted as a valid species (van Soest et al., 2012a), but considered to be a junior synonym of Tedania (Tedaniopsis) massa Ridley & Dendy, 1886. This synonymy was established by Burton (1932), because he discovered some specimens of T. (T.) massa which had a very strong, chitinous epidermal layer, similar to that of T. (T.) tantula. We here now advocate the re-establishment of the species T. (T.) tantula, as it has several differences from T. (T.) massa, as originally described by Ridley and Dendy (1887). Tedania (T.) massa was described as a massive sponge with three different parts of skeleton, differing by spicules and structure. The main spicules in this sponge are styles of ca 700 µm. Strongyles do not occur. The species T. (T.) tantula, as described by Kirkpatrick (1907; 1908), is a mostly hollow tube with a chitinous epidermis incorporating a dense, poorly organized layer of strongyles and tornotes; this description fits well with our new specimens from SYSTCO-expedition. The inner tissue contains tracts of onychaetes, which run parallel to the surface, but do not run vertically to the epidermis as it is usually found in Tedania (compare van Soest, 2002a). Also, the main spicules are reported by Kirkpatrick (1908) as strongyles of 437 µm, much smaller than the styles of T. (T.) massa. Styles are said to occur occasionally as modified, reduced strongyles. In our specimens, no styles were found. Therefore we find the arguments strong enough to consider T. (T.) tantula a valid species after all, as the distinction between the two species is usually very clear.

The two above reported specimens are not complete, even the relatively well preserved specimen SMF 11854 lacks the top. The holotype as figured by Kirkpatrick (1908) also lacks the top. Still, complete specimens were described and pictured by Burton (1932) and Koltun (1964). These sponges have distinct cap-structures, which close the tubes completely. In some cases, small oscules with chimneys can be seen on top of these caps (in Burton, 1932).

This sponge has to be discussed in comparison with the very similar new species C. antarcticum sp. nov. (see above). The new species has the same outer appearance and also some astonishing similarities in spiculation. Both species share a tough, chitinous outer membrane with dense spicules (only those in C. antarcticum sp. nov. are more dense and of clearer pattern-like arrangement) and strongyles of similar sizes as main spicules. Also, the tornotes of T. (T.) tantula and the tylotes of C. antarcticum sp. nov. are quite similar. The main difference is the occurrence of palmate isochelae in the latter species, which do not simply differentiate between the species, but also show, that they even belong to different suborders. Onychaetes occur only in T. (T.) tantula. Both species cooccur on the lower Antarctic shelf and cannot be differentiated by their outer appearance, therefore it seems probable that both species have been confused in some studies, especially when working with ROV observations only, without the possibility of skeletal studies.