Sphaerotylus raphidophora Austin, Ott, Reiswig, Romagosa & G, 2014, n. sp.

Sphaerotylus raphidophora n. sp.

Figs. 12 A–D, 13A–F

Etymology. The species name, raphidophora, reflects its raphide bearing character.

Material examined. Holotype: USNM 1231336, NOAA 2004 Exploring Alaska's Seamounts Expedition, Alvin Dive 4040, Giacomini Seamount, Gulf of Alaska, (56º 25.43′N, 146º 22.28′W), 862 m depth, Aug. 16, 2004. Description. Macroscopic features. Specimen irregular button shape about 1.6–1.7 cm in diameter by 6.9 mm (Fig. 12 A). No papillae present; however, one or more may have broken off. Colour in alcohol “yellow-brown”. Microscopic features. Skeleton composed of a palisade of megasleres, many with rounded tips protruding from the surface. Longitudal tracts of megascleres radiate out through the choanosome to end at the base of the ectosome (Fig. 12 B).

Spicules. Spicule complement includes exotyles (Fig. 13 A), two classes of tylostyles (small, Fig 13 C, D), (medium, Fig. 13 E), large subtylostyles (Fig. 13 F), and raphides (Fig. 13 B). Megascleres in the ectosome include exotyles which have a granulated head ranging from stylote to tylote (Fig. 12 C, D). They are strongylote rather than stylote at the other end. Small styles to tylostyles occur in the ectosome (Fig. 13 C) while large subtylostyles form the longitudinal tracts in the choanosome (Fig. 13 D). Additional medium size tylostyles occur between the tracts (Fig. 13 E). Raphides bundled in trichodragmata (Fig. 13 B) were found in samples from four different locations in the specimen.

Holotype USNM 1231336 Remarks. We compared spicules in our species with those in Sphaerotylus species listed in the World Porifera Database (van Soest et al. 2012) (Table 9).

Spicule type. Austin et al. Boury-Esnault Koltun Kirkpatrick Hentschel

this paper 2002 1966 1908 1914

raphidophora capitatus schoenus capitatus vanhoeffeni s. Alaska Barents Sea Arctic Antarctic Antarctic

Exotyles 568–1374 650–950 600–1250 760 504–1080

stylote-tylote tylote subtylote-tylote spherulote club granules granules granules granules granules

Lg.subtylostyles 711–1615 753–950 650–1504 1120 840–1416

Med. tylostyles 228–613 314–656 416–605 ca. 365 272–480

Sm.subtylostyles 159–271 213 below part 218

Sm. tylostyles 104–174 109–141 96–230 ca. 150 104–136

Raphides 61–80 nil nil nil nil

Spicle type Austin et al. Koltun / Plotkin Koltun / Plotkin Kirkpatrick Koltun

this paper 1970/2002 1970/2002 1908 1966 verenae sceptrum exotylotus antarcticus borealis Off BC / NW Pacific NW Pacific Antarctic Barents Sea Washington

Exotyles 1008–1459 200–250 500–850 8000 5000–7500 stylote-subtylote scepter-club chalice style-mushroom mushroom The exotyles and large tylostyles of our species are approximately the same size range as those reported by Koltun (1966) for S. capitatus (Koltun, 1966 as S. schoenus). Sphaerotylus schoenus is currently considered a junior synonym of S. capitatus. However, Sollas (1882) only named the species, giving no description nor declaring a type specimen. Sphaerotylus schoenus was considered a nomen nudum by e.g., Kirkpatrick (1908) and Boury-Esnault (2002).

Our species differs from all other described species of Sphaerotylus in having raphides in trichodragmata. These were obvious in samples taken from four different locations in the specimen, and are unlikely to be contaminants. The raphides are not simple cylinders but have lateral branches. Raphides are not unknown among the Polymastiidae. They occur in the genus Spinularia (Boury-Esnault 2002).

Sphaerotylus raphidophora also differs from S. capitatus, S. schoenus of Koltun 1966, and S. exotylotus Koltun 1970 in having longer exotyles and from S. antarcticus Kirkpatrick 1907 and S. borealis Swarschewsky 1906 in having much shorter exotyles (Table 9). The large subtylostyles of S. raphidophora are also longer than those in S. capitatus. The mushroom shaped exotyles of S. antarcticus and S. borealis differ from those of all other described species of Sphaerotylus.

Conclusions. We propose that our specimen be considered a new species, S. raphidophora, but additional material should be examined from the vicinity of the type locality.

Bathymetric range. 862 m depth.

Geographic distribution. Giacomini Seamount, Gulf of Alaska.