Stylostichon dendyi var. robustum Topsent, 1928

Van Soest, Rob W. M., 2024, Correcting sponge names: nomenclatural update of lower taxa level Porifera, Zootaxa 5398 (1), pp. 1-122 : 74

Stylostichon dendyi var. robustum Topsent, 1928

( Fig. 7M )

Stylostichon dendyi var. robustum Topsent, 1928: 285 , pl. X fig.1.

The variety was described by Topsent from north of the Azores region, Prince Albert 1 er Monaco Cruises Stat. 1420, 42.9°N 28.5125°W, depth 2460 m (two syntype specimens are in Monaco, MOM, with a type slide in Paris, MNHN DT 1212). The typical variety was described by Topsent (1890: 68, as Plumohalichondria , likewise from the Azores, Prince Albert 1 er Monaco Cruises Stat. 247, 38.97°N 30.3389°W, depth 318 m, type specimen in Monaco with a slide in Paris, MNHN DT 918). The present variety differs in the presence of two distinct isochela categories, the larger of which is clearly more robust, and its length exceeds that of the apparently single category of the typical variety, 63–80 µm versus 46 µm in the latter. The second category of chela in the present variety is 33–38 µm, similar to that of chelae of the typical variety. Topsent also described two size categories of acanthostyles for the present variety, 335–410 µm and 190–245 µm, whereas the typical variety would have only a single category of 285 µm ( Topsent 1890: 68). However, Topsent (1928: 287) admitted that he had overlooked the presence of small acanthostyles in his description of the typical variety. Still, the size of the larger acanthostyles in the present variety clearly exceeds that of the typical variety and also the thickness of the tyles is much larger, up to 40 µm in the present variety. The two varieties are almost sympatric in geographic occurrence, but differ in depth occurrence, which may possibly be responsible for the differences. Nevertheless, it appears prudent to recognize the two varieties for the time being as distinct and I propose to elevate them to valid species, to be named Phorbas dendyi ( Topsent, 1890) and Phorbas robustus ( Topsent, 1928) .

Figures

FIGURE 7. A. Polymastia isidis var. simplex Hentschel, 1914: pl. V fig. 3, B. Asbestopluma biserialis var. californiana De Laubenfels, 1935: fig. 5, C. Esperiopsis macrosigma var. novaezealandiae Dendy, 1924: pl. XIII figs. 14–20, D. Halichondria flabellifera Bowerbank, 1882: pl. VII figs. 4–10, E. Hymedesmia (Ectyodesmia) mutabilis var. costata Topsent, 1928: pl. VIII figs. 20, 22–23, F. Iophon flabellodigitatus var. gaussi Hentschel, 1914: pl. VI fig.10, G. Iophon pluricornis var. trullifera Hentschel, 1914: pl. VI fig. 9, H. Lissodendoryx isodictyalis var. paucispinosa Topsent, 1928: pl. VIII fig. 11, I. Myxilla mariana var. polysigma Topsent, 1904: pl. XIV figs. 10, J–K. Myxilla rosacea var. japonica Ridley & Dendy, 1887, J. habitus pl. XXVI fig. 3, K. spicules XXVII fig. 8, L. Pytheas rosea var. laevigata Descatoire, 1969b: fig. 4, M. Stylostichon dendyi var. robustum Topsent, 1928: pl. X fig.1.