Sphaerodoropsis heteropapillata Hartmann-Schröder, 1987

Capa, Maria & Bakken, Torkild, 2015, Revision of the Australian Sphaerodoridae (Annelida) including the description of four new species, Zootaxa 4000 (2), pp. 227-267 : 251-254

Sphaerodoropsis heteropapillata Hartmann-Schröder, 1987 new rank

Figs 4 M–N, 5I, 11

Sphaerodoropsis multipapillata heteropapillata Hartmann-Schröder, 1987: 50 –51, Figs 32–36.

Material examined. Holotype ZMH P.18875 Point Lonsdale, Geelong, Victoria, Australia, Abrasion terrace near lighthouse, on coralline algae, 24 Dec 1975.

Additional material. New South Wales: AM W.42683 (1 spec.), Split Solitary Island, 30° 14' S, 153° 10' 48" E, 15 m, 7 Mar 1991, mixed red algae; AM W.42686 (4 specs, 2 on SEM stubs), South Solitary Island, 30° 12' 07" S, 153° 15' 59" E, 14.5 m, 1 May 2005, coarse sediment; AM W.42684 (1 spec.), Burrill Rock, Ulladulla, 35° 23' 25" S, 150° 28' 11" E, 10 m, 1 May 1997, Ecklonia holdfasts. Tasmania: AM W.42678 (2 specs), Maquarie Island, 54° 30' S, 158° 57' E, 15 m, 19 Oct 1983, algae. Victoria: NMV F.90823 (2 specs), Beware reef, Cape Conran, 37° 49' 20'' S, 148° 47' 23'' E, 5 m, 15 Apr 1998, subtidal rocky reefs.

Comparative material. Sphaerodoridium multipapillata Hartmann-Schröder, 1974 , holotype, ZMH P.14336.

Diagnosis. Ellipsoid body. Dorsum with more than 50 spherical sessile tubercles in two sizes in about five transversal rows per segment, in an irregular pattern. Ventrum with 50–60 spherical papillae in two sizes in 5 irregular transversal rows. Two parapodial papillae, one each on anterior and posterior surfaces. Parapodia with 6– 10 chaetae per fascicle, blades as long as wide. Chaetae semi-compound, with shaft distally widened and blades short and wide (as long as broad), both provided of stout spines.

Re-description. Measurements and general morphology. Female with eggs. Body ellipsoid, measuring 2.8 mm long, 1.0 mm wide, with 19 chaetigers, anterior end bluntly rounded ( Fig. 11 B–C), slightly narrowing along posterior segments; convex dorsum ( Fig. 11 A) and flat ventrum ( Fig. 11 B). Segmentation inconspicuous ( Fig. 11 B–D), tegument wrinkled ( Fig. 11 A–B). Preserved specimen yellowish, lacking pigmentation.

Head. Indistinguishable rounded appendages, similar to surrounding papillae ( Fig. 11 B–C).

Tubercles. Spherical and sessile tubercles dissimilar in size present on dorsum in 5–7 irregular transversal rows with more than 50 tubercles in each chaetiger ( Figs 4 M, 11A, C–D). Ventral surface with sessile and spherical papillae dissimilar in size, with 50–60 papillae per chaetiger in five irregular transversal rows, ventral papillae somewhat smaller than dorsal tubercles ( Figs 4 N, 11B, D). Body epithelium with microscopic oblong granules ( Fig. 11 F).

Parapodia. Parapodia sub-conical, increasing in size towards chaetiger 3, around 1–2 times longer than wide in mid-chaetigers ( Fig. 11 E, G–H), and decreasing slightly towards posterior chaetigers. Acicular lobe anterior to chaetae fascicle, ellipsoid, 2–3 times longer than wide, projecting longer than ventral cirrus ( Fig. 11 G–H), with pores on distal end ( Fig. 11 H). Ventral cirri ellipsoid ( Fig. 11 G–H). Parapodial papillae spherical, one at base of anterior surface ( Figs 5 I, 11G), and one at base of posterior surface ( Figs 5 I, 10H); similar throughout chaetigers. Chaetae. Chaetal fascicles arranged in a curved transverse row behind acicular lobe, numbering 6–10 chaetae per fascicle ( Figs 5 I, 11E, G–H). All chaetae semi-compound ( Fig. 11 J–M), appearing sometimes as simple and suggesting a fusion of shaft and blades ( Fig. 11 L–M). Blades as long as wide ( Fig. 11 J–M); with an outer distal thin spine in some chaetae ( Fig. 11 L–M). Shaft with widened distal end with saw-toothed spinulation ( Fig. 11 L–M), continuing along most of blade length.

Pygidium . Pygidium terminal, with inconspicuous spherical anal cirri similar in shape as surrounding papillae ( Fig. 11 I).

Internal features. One pair of eyes as sickle-shaped dark brown or black spots deeply embedded below integument in chaetigers 2–3. Muscular pharynx not observed.

Reproductive features. Holotype and other two females with large eggs measuring approximately 130 µm. ‘Copulatory organs’ not observed in any specimen.

Variation. Specimens examined are all ellipsoid, ranging 1.0– 2.3 mm long, 0.3–0.7 mm wide, with 14–20 chaetigers and resemble the holotype in the short and inconspicuous prostomial appendages similar in shape to surrounding papillae and the shape and size of parapodia. In the original description four parapodial papillae were reported, only two have been observed after reexamination of the holotype and in additional material. Parapodial papillae are difficult to observe, and also judgment of their position as they are placed at the base of parapodia. Definition of chaetae is ambiguous. Most chaetae are simple when observed in the scanning electron microscope, although some give the impression of being semi-compound ( Fig. 11 J–M), and even break at the joint between shaft and blade ( Fig. 11 M). In the light microscope chaetae have a clear appearance of being compound ( Fig. 11 J– K), as they were described in the original description ( Hartmann-Schröder 1987: Fig. 36).

Remarks. Sphaerodoropsis heteropapillata is characterized by having relatively large dorsal tubercles of a range of sizes and by bearing semi-compound chaetae. In addition, relatively large papillae are present on the ventral side. Dorsal and ventral tubercles are arranged in irregular transversal rows being difficult to outline, especially when specimens are contracted. It was included within the informal Sphaerodoropsis Group 4 (sensu Borowski 1994) gathering species with ‘macrotubercles’ scattered in 3–4 transversal rows, together with S. multipapillata (Hartmann-Schröder, 1974) , from Tanzania. Both species also share the similar type of wide semicompound chaetae ( Hartmann-Schröder 1974a, 1987). Sphaerodoropsis heteropapillata (which only the holotype had been reported to date) was originally described as a subspecies of S. multipapillata . The geographic distance suggests it is unlikely the two represent separated populations of the same species. There are also clear differences between the species. S phaerodoropsis heteropapillata bears parapodial papillae while in S. multipapillata parapodia lack papillae ( Hartmann-Schröder 1974a, 1987; this study). Moreover, in S. heteropapillata dorsal tubercles clearly have different sizes, while in S. multipapillata papillae are of similar size. This warrants elevation of the subspecies to rank of species.

S phaerodoropsis heteropapillata also resembles a recently described species from Lizard Island, Great Barrier Reef, Sphaerodoropsis plurituberculata Capa and Rouse, 2015. Both species bear several more or less clearly longitudinal rows of spherical and sessile tubercles, variable in size, arranged in several transverse rows per segment, over dorsum and ventrum; around six semi-compound chaetae per parapodium with distally enlarged shaft and short blades, serrated, with distal long spines on the edge opposite to serration and shaft with conspicuous spinulation continuing along most of blade. Differences between these two Australian species lay in the relative length of the head appendages, number and arrangement of dorsal and ventral tubercles.

Sphaerodoropsis plurituberculata is most similar to S. heteropapillata because both species are covered with dissimilar dorsal tubercles, while in S. multipapillata these are of similar size ( Hartmann-Schröder 1974a; Hartmann-Schröder 1987; Capa & Rouse 2015). Differences between S. heteropapillata and the new species include the length of the prostomial appendages (inconspicuous in S. heteropapillata and digitiform in S. plurituberculata , at least when not contracted); the number of ventral papillae (around 50 per segment in S. heteropapillata and 30 in S. plurituberculata ); and the number of parapodial papillae ( S. heteropapillata bears one per parapodium: one at anterior surface while S. plurituberculata lacks parapodial papillae) ( Capa & Rouse 2015).

‘Copulatory organs’ have not been observed in S. heteropapillata , but in Sphaerodoropsis plurituberculata male copulatory organ were described as enlarged, bottle-shaped and porous ventral cirrus and females presented an oval and flat tubercle with a porous surface also ventral to parapodia of chaetiger 6, in addition to the ventral cirrus ( Capa & Rouse 2015).

Type locality. Point Lonsdale, Geelong, Victoria.

Distribution. Victoria, New South Wales and the Sub-Antarctic Maquarie Island, from 0 to 15 m (Hartmann- Schröder 1987, Fig. 15 ).

Habitat. Coarse sediment and among algae in subtidal rocky reefs.

Figures

FIGURE 4. Schematic illustrations of the type and arrangement of tubercles on the dorsal and ventral surface of mid-body chaetigers. The number at the left side of the drawing refer to the chaetiger number. A, C, E, G, I, K, M, O, Q, S: dorsal view. B, D, F, H, J, L, N, P, R, T: ventral view.

FIGURE 5. Schematic illustrations of the type and arrangement of parapodial and nearby structures and papillae. In all cases anterior faces left, posterior right, dorsal the top and ventral the bottom. The red cross centred in the middle of the parapodia divides each of the four hypothetical parapodial surfaces, and the concentric circles (larger at base, samller at tip) indicate the parapodial volume ..

FIGURE 11. Sphaerodoropsis heteropapillata, AM W. 42686, scanning electron micrographs. A. Complete specimen, dorsolateral view. B. Anterior end, ventral view. C. Detail anterior chaetiger and head, ventral view. D. Parapodia in mid-body chaetigers, lateral view. E. Mid-body parapodia, ventral view. F. Detail of cuticular granules. G. Parapodium mid-body chaetiger, anterior view. H. Parapodium posterior chaetigers, lateral view. I. Posterior chaetiger and pygidium, ventro-lateral view. J, K. Light micrographs of holotype. J. Chaetal fascicle mid chaetiger. K. Chaetae posterior chaetiger. L. Semi-compound chaetae anterior chaetiger, with distal spines on blade (arrow). M. Same, following chaetiger. Abbreviations: al, acicular lobe; la, lateral antenna; ma, median antenna; pa, palp; tc, tentacular cirrus; vc, ventral cirrus; 1 st, parapodium first chaetiger.

FIGURE 15. Map of Australia with collecting sites of the different species found in Australian waters (as in Table 3). A. Outline of continental Australia. B. Detail of south eastern coastline and Macquarie Island. Type locality marked by numbers and plotted according to table 3. Abbreviations: NSW, New South Wales; NT, Northern Territory; SA, South Australia; TAS, Tasmania; QLD, Queensland; WA, Western Australia.