Sphaerodoropsis fauchaldi Hartmann-Schröder, 1979

Capa, Maria & Bakken, Torkild, 2015, Revision of the Australian Sphaerodoridae (Annelida) including the description of four new species, Zootaxa 4000 (2), pp. 227-267 : 247-251

Sphaerodoropsis fauchaldi Hartmann-Schröder, 1979

Figs 4 I–L, 5H, 9, 10

Sphaerodoropsis fauchaldi Hartmann-Schröder, 1979: 122 –123, Figs 238–242; 1989: 39.

Material examined. Holotype ZMH P.15486, Port Hedland, Western Australia, sand with algae and detritus, 27 Sept 1975. Additional material. Western Australia: AM W.42679 (1 spec.), off jetty at Green Island, Rottnest Island, 32° 01' S, 115° 30' E, intertidal, 21 Dec 1983, algal turf and sediment on reef flat. Northern Territory: NTM W.10209 (1 spec.), Darwin Harbour, 12° 29' 52'', 130° 50' 18''E, 7 m, 14 Jul 1993, 7 m; NTM W.10205 (1 spec.), Darwin Harbour, 12° 31' 08'' S, E 130° 47' 05'' E, 7 m, Jul 1993; NTM W.10207 (1 spec.), Darwin Harbour, 12° 34' 52'' S, 130° 51' 03'' E, 6 m, 13 Jul 1993; NTM W.15192 (1 spec.), Darwin Harbour, 12° 33' 45''S, 130° 52' 01'' E, 3 m, 18 Mar 1994; NTM W.10204 (1 spec.), Darwin Harbour, 12° 31' 13'' S, 130° 56' 02'', 11 m, 16 Jul 1993. New South Wales: AM W.42692 (1. spec.), Red Head, 32° 03' 17" S, 152° 33' 14" E, 22 Mar 2003, 13 m, sand and rocky reef; AM W.42687 (2 specs), Surgeons Reef, North West Solitary Island, 30° 00' 27" S, 153° 16' 13" E, 11 m, 30 Apr 2005, sand and shelly sediment; AM W.42706 (1 spec.), Bass Point, 34° 36' S, 150° 54' E, 1 Feb 1991, 45 m; AM W.42690, (2 specs), S. of Baronda Head, Tathra, 36° 41' 12" S, 149° 59' 53" E, 11 m, 5 Apr 2008, Ecklonia holdfasts; AM W.42696 (2 spec.), NE side Little Broughton Island, north-east of Port Stephens, 32° 37' 05" S, 152° 20' 06" E, 17 m, 11 Mar 2006, alga Ecklonia holdfasts; AM W.42697 (1 spec.), Esmeralda Cove, Broughton Island, Port Stephens, 32° 37' 19" S, 152° 19' 10" E, 18 m, 12 Mar 2006, coarse shelly sediment; AM W.42698 (1 spec.), Esmeralda Cove, Broughton Island, Port Stephens, 32° 37' 19" S, 152° 19' 10" E, 18 m, 12 Mar 2006, bushy brown algae; AM W.42689 (1 spec.), E. of Baronda Head, Tathra, 14 m, 4 Apr 2008, among red algae and bryozoans; AM W.42685 (1 spec.), Halfway Reef, Ulladulla, 35° 21' 25" S, 150° 29' 19" E, 15 m, 3 May 1997, sponges, bryozoan and hydrozoan; AM W.42686 (2 spec.), north west end of South Solitary Island, 30° 12' 07" S, 153° 15' 59" E, 14.5 m, 1 May 2005, coarse sediment; MZH P. 20094 (3 specs), Malua Bay, Batemans Bay, 4 Jan 1976. Victoria: NMV F. 90824 (1 spec.), Schomberg Reef, near Peterborough 38° 36' 49" S, 142° 53' 19" E, 13 May 1998; NMV F.90825 (1 spec.), Mutton Bird Island, near Port Campbell, 38° 38' 55" S, 143° 03' 46" E; NMV F.132899, Central Bass Strait, 38° 30' 12" S, 144° 15' 00" E; NMV F.217162, 11.7 km W of Pt Ricardo, Eastern Bass Strait, 37° 49' 53'' S, 148° 30' 07'' E, 27 m, Feb 1991, coarse sand.

Diagnosis. Ellipsoid body with 10–14 longitudinal rows of spherical macrotubercles, in two transversal rows per segment, with 8–12 macrotubercles in a row between parapodia and 10–14 in posterior row. Dorsum with spherical papillae in two longitudinal rows next to parapodia. Ventrum with two longitudinal rows of large tubercles, near parapodia and four longitudinal rows of spherical papillae. One papilla on anterior surface of each parapodium. Parapodia with 5–6 chaetae per fascicle, slightly enlarged distally, blades 3–4 times as long as wide. Both females and males with porous swollen ventral cirri, in chaetigers 4–7 and 5–8, respectively; additionally, females bear with porous tubercle-like structure ventral to parapodia of chaetiger 6.

Re-description. Measurements and general morphology. Body ellipsoid, 0.8 mm long and 0.4 mm wide, with 16 chaetigers. Dorsum convex, ventrum flattened ( Fig. 9 A, C). Segmentation inconspicuous, tegument with transverse wrinkles ( Fig. 9 A–D). Preserved specimen lacking pigmentation.

Head. Anterior end bluntly rounded ( Fig. 9 A–B). Prostomium with five digitiform appendages, including a pair of short palps in a ventral position, a pair of lateral antennae and a median antenna; lateral antennae similar in size and shape to palps; median antenna, about as long as lateral antennae ( Fig. 9 C). Antenniform papillae not observed. A pair of tentacular cirri shorter than lateral antenna. A few scattered papillae present on the head ( Fig. 9 C).

Tubercles. Dorsal macrotubercles sessile and spherical. First chaetiger with two transversal rows of four and five macrotubercles each. Following chaetigers with 17 longitudinal rows of macrotubercles, arranged in double transversal rows on each segment (with 8 and 9 tubercles each), decreasing in size from dorsal-most to lateral rows ( Figs 4 I, 9A). Additional single spherical papilla above each parapodia ( Figs 4 I, 9A, D). Two large spherical macrotubercles close to the base of each parapodium, forming four longitudinal rows on ventrum ( Figs 4 J, 9A–B, D). Additional small spherical papillae in four longitudinal rows, leaving a gap mid-ventrally without papillae ( Figs 4 J, 9A, D–E). Body epithelium with irregular granules ( Fig. 10 D).

Parapodia. Parapodia sub-conical, about 1–2 times longer than wide. Chaetigers with digitiform acicular lobe, present from chaetiger 2, projecting longer than ventral cirrus ( Fig. 9 D–G, I, 10C); ventral cirri bottle-shaped ( Fig. 9 D, G, I). One spherical papilla on each parapodium on the anterior surface, variable in size ( Figs 5 H, 9G, I, 10C–D).

Chaetae. Compound chaetae present in all chaetigers, arranged in curved transverse rows posterior to acicular lobe, numbering 5–6 per fascicle ( Figs 5 H, 9E–F, I). Shaft with slender distal end with long spinulation on edge ( Figs 9 K–L, 10 E–G). Blades varying in shape and size within fascicle, ranging 2–4 times longer than maximum width, with a distal recurved tip, fine spinulation on cutting edge and 1–3 thin spines on outer distal margin ( Figs 9 J–L, 10E–G).

Pygidium . Pygidium sub-terminal, with a mid-ventral digitiform anal cirrus ( Fig. 9 A).

Internal features. Eyes not seen in holotype, but a pair observed in other specimens, in first chaetiger. Muscular pharynx not observed.

Reproductive features. Gender of holotype unknown, gametes or ‘copulatory organs’ not observed. Females with a porous tubercle-like structure ventral to parapodia of chaetiger 6 and modified ventral cirri present in chaetigers 4–7 ( Fig. 9 D–F), with a swollen base with pores scattered over the surface and a distal knob ( Figs 4 J, 9G–H). Few oblong eggs measuring 200 µm in length were observed in two specimens. Male (NMV F.132899) with modified ventral cirri present in chaetigers 5–8, with a swollen and porous base and a distal knob, similar in morphology to those found in the females ( Fig. 4 L), and sperm packages distributed along the coelom.

Variation. Specimens measuring 0.8–3.1 mm long and 0.1–0.6 mm wide, with 11–27 chaetigers. One preserved specimen (NTM W.10206) showed red dots of pigment over parapodia; pigmentation not conspicuous in other specimens. Prostomial appendages digitiform in relaxed specimens, blunt and wide at basis in specimens where anterior end is contracted. Macrotubercles increasing in number from first to mid-body chaetigers. Transversal rows of tubercles are indistinct in contracted specimens and macrotubercles seem arranged randomly. The number of macrotubercles in each transversal row seems to be dependent on size of specimen, small specimens with 8–10+9–12 macrotubercles ( Figs 4 K, 10A–B), and 10–12+ 12–14 in larger specimens ( Figs 4 I, 9A), and the size of tubercles, also seem larger in small specimens (e.g. Figs 4 K, 10A). A couple of specimens showed atypical tubercles, with a distal swelling ( Fig. 10 B), considered herein as an artefact. The number and size of ventral tubercles and papillae show some variation and in some specimens three pairs of longitudinal rows have been observed ( Fig. 4 L). Number and morphology of chaetae similar in all specimens examined. Some variation in the size and morphology of chaetae was observed among specimens. Larger individuals seem to bear more slender and similar blades within and across chaetigers (e.g. Fig. 9 J–L) while smaller specimens presented a wider range in sizes of blades and included shorter and wider ones ( Fig. 10 G). Nevertheless, in all cases chaetae presented shafts distally provided with long spines and spines also in the distal outer edge of the blades.

Remarks. The specimens studied mostly agree with the original description ( Hartmann-Schröder 1979). The original description is not accurate on details regarding prostomial appendages, variability in size and arrangement on epithelial tubercles and chaetal morphology. Nevertheless, the original description is in line with what can be confirmed here from observations in the holotype, and from additional material.

This species belongs in Group 3 (sensu Borowski 1994), gathering species with more than four longitudinal rows and two transversal rows of macrotubercles per segment. Sphaerodoropsis fauchaldi is unique among other congeners in having a larger number of longitudinal rows of macrotubercles and large tubercles on the ventral side. Sphaerodoropsis megatuberculata n. sp. have as many longitudinal rows of macrotubercles as observed in smaller specimens of S. fauchaldi , but S. megatuberculata n. sp. has large ellipsoid to cylindrical macrotubercles and lack the characteristic large ventral tubercles. Only two other Sphaerodoropsis species have conclusively been reported to have presence of macrotubercles on the ventral side, S. malayana Augener, 1933 , S. solis Reuscher and Fiege, 2011 , but only the latter belong to Group 3 ( S. malayana has four longitudinal rows of macrotubercles on the dorsum). Sphaerodoropsis solis has up to 13 (6+7) longitudinal rows of macrotubercles while S. fauchaldi has up to 26 (12+14) longitudinal rows of macrotubercles. Of species currently accepted in Sphaerodoropsis only S. spissum Benham, 1921 possesses a number of macrotubercles within the range described for S. fauchaldi . The original description of S. spissum does not describe enough details to compare necessary characters, and it seems to lack the ventral macrotubercles. It has not been possible to trace type specimens of S. spissum (see comments on S. spissum below).

Originally described from the northern part of Western Australia this species was also reported from New South Wales in a later survey ( Hartmann-Schröder 1989). Despite the wide geographic distribution ( Fig. 15 ) representing different environments from the tropical north to the temperate south-east it has not been possible to observe conclusive morphological differences on specimens from Western Australia, Northern Territory, New South Wales and Victoria in this study, confirming earlier records and the observed variability in number of macrotubercles, and other morphological traits, is here considered to be related to size of specimens. Pending more available specimens of different size classes or specimens collected from more localities should reveal if the species is broadly distributed along the East Australian coastline or if the disjunct populations truly represent distinct species.

Habitat. In coarse sand, rocks or as epibionts of algae and Bryozoa; from 3 to 45 m.

Type locality. Port Hedland, Western Australia ( Fig. 15 ).

Distribution Western Australia, Northern Territory, New South Wales and Victoria, Australia ( Fig. 15 ).

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 9. Sphaerodoropsis fauchaldi, NTM W. 10206, scanning electron micrographs. A. Complete specimen, ventro-lateral view. B, Anterior end, ventral view. C. Detail anterior end and head appendages, ventral view. D. Chaetigers 9 – 5 (left to right), ventral side, with female inflated and porous ventral cirri (white arrows) in chaetigers 7 – 5. E. Same, opposite side, with inflated and porous ventral cirri (white arrows) in chaetigers 7 – 5 and oval tubercle (black arrow) on chaetiger 6. F. Parapodia, chaetigers 6 – 4, with ‘ copulatory organs’ (arrows). G. Parapodia of chaetigers 8 (with normal ventral cirrus) and 7 (with copulatory organ), antero-lateral view. H. Detail of copulatory organ in chaetiger 6 with pores scattered on the surface. I. Parapodium chaetiger 8, anterior view. J. Chaetal fascicle, mid-body chaetiger. K. Chaetae chaetiger 5. L. Chaeta posterior chaetiger. Abbreviations: al, acicular lobe; co, copulatory organ; la, lateral antenna; ma, median antenna; pa, palp; tc, tentacular cirrus; vc, ventral cirrus.

FIGURE 10. Sphaerodoropsis fauchaldi, NMV F. 217162. A. Whole specimen, dorsal view (anteror end on top). B. Dorsal macrotubercles, posterior chaetigers. C. Parapodium mid-body, anterior view. D. Same, dorsal view. E. Compound chaeta, chaetiger 3. F. Chaetae, mid-body parapodium (arrow pointing to the distal spine in blade). G. Shorter blade, chaetae in midbody parapodium. Abbreviations: al, acicular lobe; vc, ventral cirrus.

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.