Gellius carduus var. magellanica Ridley & Dendy, 1886

Van Soest, Rob W. M., 2024, Correcting sponge names: nomenclatural update of lower taxa level Porifera, Zootaxa 5398 (1), pp. 1-122 : 35

Gellius carduus var. magellanica Ridley & Dendy, 1886

( Fig. 3I )

Gellius carduus var. magellanica Ridley & Dendy, 1886: 333 ; Ridley & Dendy 1887: 40, pl. XIII fig. 6.

? Adocia carduus ; Burton 1932: 274.

The variety was described by Ridley & Dendy from Strait Magellan, Challenger Expd. Stat. 311, 52.7582°S 73.7667°W, depth 448 m (wet holotype specimen BMNH 1887.5.2.256). It differed from the typical variety described as Gellius carduus by Ridley & Dendy from Crozet Islands Challenger Exped. Stat. 148a, 46.8833°S 51.8667°E, depth 439–1006 m, and nearby Prince Edward Islands, syntypes BMNH 1887.5.2.254, 258 and 263) in habitus (oval massive vs leaf-shaped), oxea shape (true oxeas vs strongylote oxeas), and oxea size (490 vs. 600 µm). Burton (1932: 274), treating sponges from the Falkland Islands and Magellan region synonymized the two varieties and included Gellius laevis Ridley & Dendy, 1886 into an extended species Gellius carduus (as Adocia ). For the combined species Burton cited oxea lengths varying between 300 and 450 µm, clearly in contrast with Ridley & Dendy’s oxea length of 600 µm for the types of Gellius carduus , but conforming to the length of G. carduus var. magellanica . In a following comparison with Gellius glacialis Ridley & Dendy (1886) on the next page (Burton 1932: 275) he provided a new oxea length range for G. carduus as 490–600 µm, and this compares rather closely with oxeas of G. glacialis (530–650 µm). Burton ‘suspected’ that G. carduus belongs to G. glacialis , but the size of the sigmas of the latter (146 µm) precluded this synonymization.

I do not believe Burton’s (1932) treatment of the Challenger Gellius specimens is accurate. The species within the genus Gellius (currently a subgenus of Haliclona ) are subtly different in the shapes and sizes of megascleres and microscleres. Construing that specimens of Gellius may have widely variable lengths and shapes in these skeletal features undermines the taxonomic framework of recognizing species. The fact that the spicule shape and size of his Falkland region material conforms closely with Gellius carduus var. magellanica , and not with the type material of G. carduus appears to show that the two varieties from their distant localities are probably distinct taxa. Confirmation by molecular sequence data may be necessary, but for the time being I propose to distinguish the Southern South American populations ( Falkland Islands, Shag Rock, South Shetland Islands) as a distinct subspecies Haliclona (Gellius) carduus subsp. magellanica ( Ridley & Dendy, 1886) .

Figures

FIGURE 3. A. Amorphina grossa f. latissima Czerniavsky, 1880: pl. III (VII) fig. 23a, B–E. Callyspongia rigida Desqueyroux- Faúndez, 1984, B. spicules fig. 25, C. habitus fig. 182, D– E. skeleton figs. 183–184, F. Chalinissa elongata var. tenuispicula Thum, 1903: figs. 8–9, G. Gelliodes benedeni var. fortior Topsent, 1917: pl. VI fig. 22, H. Gelliodes carnosa var. laxa Dendy, 1922: pl. 2 fig. 1, I. Gellius carduus and G. carduus var. magellanica Ridley & Dendy, 1886, Ridley & Dendy, 1887: pl. XIII figs. 6–7, J. Gellius glacialis var. nivea Ridley & Dendy, 1886, Ridley & Dendy, 1887: pl. VIII fig. 8, K. Gellius raphidiophorus Brøndsted, 1933: fig. 7, L. Sigmadocia tubuloramosus; Bergquist & Warne, 1980: pl. 9a.