Hymedesmia (Stylopus) pharos, Goodwin & Brickle, 2012

Goodwin, Claire & Brickle, Paul, 2012, Sponge biodiversity of South Georgia island with descriptions of fifteen new species, Zootaxa 3542, pp. 1-48 : 19-21

Hymedesmia (Stylopus) pharos sp. nov.

( Figure 11)

Type material: Holotype: BELUM Mc 7626. Sample in 95% ethanol, tissue section and spicule preparation on slides; Right Whale Bay, South Georgia (54°00.173’S, 37° 40.856’W); depth 18m; collected by C. Goodwin, J. Brown and S. Brown, 21 st November 2010.

Chelae External appearance/Notes/Distribution

24–33 Encrusting. Orange to orange–brown. New Zealand.

Authors termed tornotes ‘anisostrongyloxea’.

22– 36 Type locality Antarctic. Boury–Esnault and Van Beveren

(1982) raised Hentschel’s variety H. simillima var. antarctica to species status. Recorded South Georgia by Burton (1932).

19.5 Originally described as Myxilla decepta . Reddish–brown encrusting.

15.3 Currently classified as Hymedesmia (van Soest et al. 2012) but may require revision. Larger chelae arcuate, smaller unguiferate, also possesses ‘chelate bipocoella’ 8µm). Type loclity Winter Quarters,

Antarctica.

30–38 From Hentschel (1914)

30– 37 Type locality Antarctic.

30 Also has sigmas 25µm. Type locality Calbuco , Chile. Recorded

Falkland Islands Burton (1932) but specimen has mucronate rather than strongylote tornotes so unlikely to be same species.

26– 30 Type locality Antarctic.

60 New Zealand. Encrusting on bryozoan.

strongly curved.

23–36 Differs from H. antarctica in that tornotes shorter than acanthostyles (Boury–Esnault and Van Beveren 1982).

18–30 Auckland, New Zealand. Orange–brown, thin.

30 Also has sigmas 45µm. Type locality Calbuco , Chile .

24 Type locality McMurdo Sound, Antarctic. Thin encrustation

12 on algae. Smaller chelae are unguiferate.

24–30 Bright orange encrusting species with prominent pore sieves.

Type locality South Georgia.

Paratypes: Samples in 95% ethanol, tissue section and spicule preparation on slides. BELUM Mc 7668 and BELUM Mc 7669. Husvik, South Georgia (54°10.285’S, 36° 40.412’W); depth 18m; collected by C. Goodwin, D. Poncet and P. Brewin, 26 th November 2010 . BELUM Mc 7680. Green Island , Stromness, Site 1, South Georgia (54°09.448’S, 36° 39.752’W); depth 17.4m; collected by C. Goodwin, P. Brickle and S. Cartwright, 27 th November 2010 .

Comparative material examined: Hymedesmia longuiroides Burton Spicule preparation slide BMNH 28.11.15468a.

Etymology: Named for the expedition vessel the M.V. Pharos S.G. and her crew (as a noun in apposition).

External morphology: In situ appearance: Bright orange thinly encrusting (<3mm) sponge with densely packed pore sieves. Encrusting on bedrock, patches up to 20cm in diameter ( Fig. 11a).

Preserved appearance: Thin white crust.

Skeleton: Basal layer of acanthostyles with ascending columns of 2–6 ectosomal oxeas ( Fig. 11b).

Spicules: Measurements from Mc7626.

Primary acanthostyles: 252(283)314 by 8.8(12.5)17.1µm. Head very slightly tylote. Entirely but sparsely spined, spines smaller than those on the echinating acanthostyles ( Fig. 11c).

Echinating acanthostyles: 136(150)168 by 8.0(11.5)14.9µm. Head not tylote. Entirely spined, spines on shaft have tips curved down towards head ( Fig. 11d).

Ectosomal tornotes: 205(240)282 by 4.6(6.6)8.4µm Fusiform, oxea like, tornotes with abrupt points ( Fig. 11e, f).

Remarks: The majority of Southern Ocean and Antarctic Hymedesmia (Stylopus) species have strongyles or tylo-strongyles as ectosomal spicules ( Table 6). Hymedesmia (Stylopus) longurioides Burton, 1932 has similar sized spicules and tornotes as ectosomal spicules and was described from Shag Rocks between South Georgia and the Falkland Islands. This possesses acanthostyles of a similar length but in contrast to our species the larger acanthostyles are almost entirely spined with just a small gap at the tip, and spines on both categories of acanthostyles are smaller and denser. This species is very similar in appearance to Hymedesmia (Hymedesmia) barnesi sp. nov.; however it lacks visible surface channels and on microscopic examination can be readily distinguished from H. barnesi by its lack of chelae.