Sphaerephesia hutchingsae, Capa, Maria & Bakken, Torkild, 2015

Capa, Maria & Bakken, Torkild, 2015, Revision of the Australian Sphaerodoridae (Annelida) including the description of four new species, Zootaxa 4000 (2), pp. 227-267 : 238-241

Sphaerephesia hutchingsae n. sp.

Figs 4 C–D, 5E, 6

Material examined. Holotype: East of Malabar, Sydney, New South Wales, Australia, AM W.42748, 33° 58' 43" S, 151° 18' E, 82 m, 22 Aug 1995. Paratypes: east of Malabar, Sydney, New South Wales, AM W.42717 (1 spec.), 33° 58' 41" S, 151° 17' 51" E, 80.1m, 17 Oct 1995; AM W.42719 (1 spec.), 33° 58' 36" S, 151° 17' 54" E, 80.1m, 15 Nov 1995; AM W.42721 (1 spec.), 33° 58' 43" S, 151° 18' 00" E, 82.3 m, 23 Jul 1996; AM W.42730 (1 spec.), 33° 58' 43" S, 151° 17' 54" E, 81.5 m, 23 Jul 1996; AM W.42731 (2 specs), 33° 58' 41" S, 151° 17' 54" E, 80.7 m, 19 Sep 1995; AM W.42749 (1 spec.), 33° 58' 43" S, 151° 17' 54" E, 81.7 m, 22 Aug 1995; AM W.42751 (1 spec.), 33° 58' 43" S, 151° 17' 48" E, 80.9 m, 19 Jun 1996; AM W.42752 (2 specs), 33° 58' 43" S, 151° 17' 54" E, 81.6 m, 19 Jun 1996; AM W.42758 (1 spec.), 33° 58' 46" S, 151° 17' 57" E, 81.8 m, 23 Jul 1996. Additional material. New South Wales: AM W.42705 (1 spec.), Bass Point, 34° 36' S, 150° 54' E, 45 m, 0 1 Feb 1990; AM W.42707 (1, spec.), Cape Banks, 34° 00' S, 151° 16' E, 65 m, 0 3 Jan 1991; AM W.42708, (1 spec.), same collection details; AM W.42709 (1 spec.), same collection details; AM W.42710 (1 spec. bad conditions), same collection details; AM W.42713 (1 spec.), south-east of Bate Bay, 34° 04' 36" S, 151° 13' E, 46 m, 15 Jan 1990; AM W.42715 (2 specs), off Providential Head, Wattamolla, 34° 08' S, 151° 08' 30" E, 65 m, 29 Oct 1990; AM W.42716 (1 spec.), Bass Point, 34° 36' S, 150° 54' E, 35 m, 29 Oct 1990; AM W.42718 (1 spec.), east of Malabar, 33° 58' 41" S, 151° 18' 00" E, 81.7 m, 21 Dec 1995; AM W.42722 (1 spec.), east of Malabar, 33° 58' 46" S, 151° 18' E, 81.1 m, 26 Feb 1996; AM W.42723 (1 spec.), east of Malabar, 33° 58' 36" S, 151° 17' 48" E, 81.2 m, 0 8 Dec 1995; AM W.42724 (1 spec.), east of Malabar, 33° 58' 43" S, 151° 17' 51" E, 79.5 m, 17 Apr 1996; AM W.42725 (1 spec.), east of Malabar, 33° 58' 41" S, 151° 18' 00" E, 81.6 m, 17 Oct 1995; AM W.42726 (2 specs), east of Malabar, 4 km south of ocean outfall, 34° 00' 30" S, 151° 16' 45" E, 82.5 m, 20 Jun 1996; AM W.42727 (2 specs), east of Malabar, 33° 58' 36" S, 151° 18' E, 81.2 m, 21 Sep 1995; AM W.42728 (2 specs), east of Malabar, 33° 58' 41" S, 151° 18' E, 81.4 m, 23 Aug 1995; AM W.42729 (1 spec. bad conditions), east of Malabar, 33° 58' 36" S, 151° 17' 48" E, 80.1 m, 17 Oct 1995; AM W.42732 (1 spec.), east of Malabar, 33° 58' 41" S, 151° 17' 54" E, 80.9 m, 19 Jun 1996; AM W.42733 (2 specs), east of Malabar, Sydney, 33° 58' 43" S, 151° 17' 57" E, 81.9 m, 23 Aug 1995; AM W.42734 (2 specs, one used for SEM), east of Malabar, 33° 58' 41" S, 151° 18' E, 81.6 m, 17 Jan 1996; AM W.42736 (1 spec.), east of Malabar, 33° 58' 38" S, 151° 18' E, 82.1 m, 23 Aug 1995; AM W.42737 (1 spec.), east of Malabar, 33° 58' 46" S, 151° 17' 51" E, 80.3 m, 19 Sep 1995; AM W.42738 (1 spec.), east of Malabar, Sydney, 33° 58' 43" S, 151° 17' 54" E, 79.5 m, 17 Jan 1996; AM W.42739 (1 spec.), east of Malabar, 33° 58' 36" S, 151° 17' 57" E, 81.5 m, 20 Feb 1996; AM W.42740 (1 spec.), east of Malabar, 33° 58' 38" S, 151° 17' 54" E, 81.5 m, 19 Jun 1996; AM W.42747 (1 spec.), east of Malabar, 33° 58' 38" S, 151° 17' 54" E, 8.7 m, 17 Oct 1995; AM W.42753 (1 spec. for SEM), east of Malabar, 33° 58' 36" S, 151° 17' 54" E, 81.6 m, 19 Dec 1995; AM W.42754 (1 spec.), east of Malabar, 33° 58' 38" S, 151° 18' 00" E, 81.6 m, 17 Oct 1995; AM W.42755 (1 spec.), east of Malabar, 33° 58' 36" S, 151° 17' 51" E, 82.4 m, 17 Oct 1995; AM W.42756 (1 spec.), east of Malabar, 33° 58' 41" S, 151° 18' 00" E, 81.2 m, 19 Jun 1996; AM W.42757 (1 spec.), east of Malabar, 33° 58' 41" S, 151° 17' 48" E, 79.7 m, 15 Nov 1995. Victoria: NMV F.132843 (2 specs), Central Bass Strait, 100 km SSE of Cape Liptrap, 39° 45' 54" S, 145° 33' 30" E, 74 m, 13 Nov1981; NMV F.132864 (5 specs), Central Bass Strait, 66 km S of Rodondo Island, 39° 49' 30" S, 146° 18' 30" E, 82 m, 13 Nov 1981; NMV F.132869 (5 specs), Central Bass Strait, 26 km SE of Aireys Inlet, 38° 39' 48" S, 144° 18' 12" E, 79 m, 19 Nov 1981; NMV F.63833 (1 spec.), Eastern Bass Strait, 7.3 km SSW of Cape Conran, 37° 52' 39" S, 148° 42' 09" E, 49 m, 0 4 Jun 1991; NMV F.69678 (2 specs), Eastern Bass Strait, 15.3 km of eastern edge of Lake Tyers, 37° 53' 13" S, 148° 15' 14" E, 43 m, Feb 1991; NMV F.69679 (2 specs), Eastern Bass Strait, 20.2 km of Pt Ricardo, 37° 52' 25" S, 148° 25' 03" E, 46 m, 26 Sep 1990.

Comparative material: Sphaerephesia fauchaldi Kudenov, 1987 , holotype NMNH 102785; Sphaerephesia longisetis Fauchald, 1972 , holotype AHF POLY 0964; S phaerephesia regularis Böggemann, 2009 , holotype ZMH P25498, paratypes ZMH P25497 (4 specs), ZMH P25499 (4 specs); Sphaerephesia similisetis Fauchald, 1972 , paratype AHF POLY 0 967 (2 specs).

Diagnosis. Body slightly flattened dorso-ventrally (wider than high), with four longitudinal rows of sessile, pear-shaped macrotubercles with small spherical terminal papillae (often not conspicuous) and 4–5 transversal rows of small spherical papillae per segment. Distance between dorsal-most macrotubercles exceeds distance between those and lateral ones. Parapodia with ventral cirri as long as acicular lobe and 14–16 rounded and small papillae, sometimes a distal one, on dorsal surface slightly larger. Parapodia with 14–20 compound chaetae, with thin shafts and blades 10–12 times as long as wide.

Description. Measurements and general morphology. Gravid female, 2 mm long, 0.5 mm wide; 20 chaetigers. Body ellipsoid, slightly flattened dorso-ventrally (wider than high). Dorsum convex, slightly sub-trapezoidal, and ventrum flattened ( Fig. 6 A–B). Tegument with transverse wrinkles and segmentation only slightly discernible in some segments ( Fig. 6 A). Preserved specimen lacking pigmentation.

Head. Anterior end bluntly rounded ( Fig. 6 A, C). Prostomium with seven longer appendages, including a pair of palps, in ventral-most position near the mouth, sub-conical and wrinkled; a pair of lateral antennae, similar in shape and size to palps; a median antenna, shorter (two thirds) than lateral antennae and with a rounded distal end; and a pair of antenniform papillae behind lateral antennae, slightly shorter than lateral antennae ( Fig. 6 C–D). Around 20 digitiform smaller papillae are confined by prostomial appendages and the mouth in frontal view ( Fig. 6 D). A pair of tentacular cirri similar in shape and size to lateral antennae and palps and several scattered papillae similar to prostomial.

Tubercles. First chaetiger with two macrotubercles, sessile, pear-shaped or provided with an incipient rounded terminal papillae ( Fig. 6 A–D). Rest of chaetigers with four macrotubercles each arranged in four longitudinal rows along dorsum ( Figs 4 C, 6A–B). Distance between mid-rows is larger than between these and lateral rows of macrotubercles ( Figs 4 C, 6A–B). Shape and size of all macrotubercles similar, slightly increasing in size in first four chaetigers ( Fig. 6 A, E) and also slightly reducing in size in posterior chaetigers towards pygidium . Macrotubercles with pores arranged mainly in three groups around terminal papilla ( Fig. 6 F). Spherical papillae present over dorsum, arranged in five transversal rows per segment ( Fig. 6 A), around 25 papillae present between mid-macrotubercles and 8–10 between these and the lateral ones in mid-segments, one of them, larger than the others ( Fig. 4 C). One to three papillae between lateral macrotubercles and parapodia. Ventral surface with small spherical papillae, arranged in 5–6 transversal rows, with a total of around 30 papillae per segment, in mid-body; numbers decreasing towards posterior end ( Figs 4 D, 6I). Body epithelium with ellipsoid granules (e.g. Fig. 6 F).

Parapodia. Parapodia sub-conical, increasing in size towards chaetiger 5 and around 1–2 times longer than wide, wrinkled ( Fig. 6 G–J). Acicular lobe projecting distally anterior to chaetae ( Fig. 6 G–J). Ventral cirri subconical–pear-shaped as long as acicular lobe ( Fig. 6 I, J). Mid-body parapodia with around 12–13 small spherical papillae, all similar in size: 4–5 on dorsal surface, two distal ones larger, 2–3 on anterior surface, 3–4 on ventral surface and 1–2 on posterior surface ( Figs 5 E, 6G–I).

Chaetae. Compound chaetae present in all chaetigers, arranged in a curved transverse row around acicular lobe and numbering 14–20 per fascicle in mid-body chaetigers ( Figs 5 E, 6I –K). Shaft with slightly widened distal end with delicate, almost inconspicuous spinulation ( Fig. 6 K). Blades similar in length along fascicles (10–12 times longer than maximum width), only slightly longer than those from mid-fascicle, with fine and short spinulation along superior edge and a distal recurved tip ( Fig. 6 J–K).

Pygidium . Pygidium terminal, with mid-ventral digitiform anal cirrus and a pair of dorsal anal cirri, similar in shape to macrotubercles but slightly smaller.

Internal features. Eyes not observed in any specimen. Muscular pharynx runs along chaetigers 1–4.

Reproductive features. Holotype and a few of the additional specimens examined are gravid females carrying large discoid eggs, 200 µm in diameter that occupy most of the body coelom, from the anterior to the posterior segments (e.g. AM W.42708, AM W.42715, AM W.42748), other specimens seem to be filled with sperm. However, ‘copulatory organs’ are not obvious in either females or males.

Variation. Paratypes and additional material examined measure 1–2 mm long and 0.3–0.5 mm wide (without parapodia), with 13–23 segments, in all cases body is about 3–4 times longer than wide. Variation of relative size of head appendages is quite stable and median antenna is the shorter appendage, but in some individuals the antenniform papillae are not distinct. Relative size of parapodia varies with and between specimens from 1–3 times longer than wide. Parapodial papillae are often difficult to count under light microscopy but numbers are constant, only in some specimens the three larger distal dorsal papillae have been spotted ( Fig. 5 E). Relative length of blades of falcigers is variable within parapodia but the range is fixed between specimens (10–12 times longer than maximum width). Muscular pharynx runs from chaetigers 1 to 4–5. In specimens immersed in blue methylene, only the four longitudinal rows of macrotubercles stained deep blue.

Remarks. Sphaerephesia is a genus with eight nominal species ( Alalykina 2015). Five of them, Sphaerephesia similisetis Fauchald, 1972 , S. longisetis Fauchald, 1972 , S. chilensis Fauchald, 1974 , S. fauchaldi Kudenov, 1987 and S. regularis Böggemann, 2009 , have been described with four rows of macrotubercles with a terminal rounded papilla, several additional papillae on dorsal surface, and falcigers with long blades, features also found in Sphaerephesia hutchingsae n. sp. Sphaerephesia regularis is distinguished from the new species in the different general body shape, cylindrical and slender instead of oval, wide and flattened dorso-ventrally. Moreover, the rows of macrotubercles are very close to each other, almost in contact, unlike in the rest of species ( Böggemann 2009). The other taxa are mainly distinguished by the number of parapodial papillae. Sphaerephesia chilensis has one or two parapodial papillae, S. fauchaldi has eight, S. longisetis around 15 and S. similisetis around 20–25 ( Fauchald 1972, 1974; Kudenov 1987a), although these numbers were erroneously interpreted for S. longisetis and S. similisetis in recent publications (original descriptions in Fauchald 1972 versus Magalhães et al. 2011 or Alalykina 2015). The latter two are the most similar to S. hutchingsae n. sp. with around 15 parapodial papillae. Sphaerephesia longisetis , S. similisetis and the new species share the number and arrangement of dorsal papillae (in five more or less clear transverse rows), the presence of a prominent acicular lobe and a ventral cirrus similar in shape and size, and little variation of blade length on each chaetal fascicle ( Fauchald 1972). Sphaerephesia similisetis and S. longisetis were described lacking antenniform papillae ( Fauchald 1972), but these have been observed in types of the former, a feature shared by S. hutchingsae n. sp. Other differences between S. longisetis and S. hutchingsae n. sp. include the extremely long characteristic chaetae and the presence of microtubercles of S. longisetis being absent in the Australian species. Microtubercles have, however, not been observed on the holotype of S. longisetis after direct examination, and all the small tubercles were spherical and had no distinct collar or terminal papillae. Differences between S. similisetis and S. hutchingsae n. sp. also rely in the number of parapodial papillae.

The terminal papillae on macrotubercles are often not conspicuous and well delineated in some species of Sphaerephesia and these tubercles show a pear-shaped outline. This is the case for at least S. mamalaensis ( Magalhães et al., 2011) , S. regularis and S. similisetis ( Magalhães et al. 2011; Böggemann 2009; pers. obs.). There are also some specimens currently considered as Sphaerodoropsis , such as S. philippi Fauvel, 1911 , S. biserialis Berkeley & Berkeley, 1944 , S. anae Aguado and Rouse, 2006 and S. protuberanca Böggemann, 2009 that have four longitudinal rows of macrotubercles with similar morphology (provided with a terminal papillae or at least being pear-shaped) and could in fact be related to the former ones. Since the presence of macrotubercles with terminal papillae has been considered the main features to distinguish between Sphaerephesia and Sphaerodoropsis , a deep revision of members of these two groups and a reassessment of the systematic value of this feature is needed.

Etymology. This species is dedicated to Pat Hutchings for her contribution to polychaete taxonomy for several decades, her continuous support and friendship.

Distribution. Specimens have been found south of Sydney (New South Wales) and in Eastern and Central Bass Strait (Victoria) ( Fig. 15 ).

Ecology. The species has only been found in samples with fine sediments (muddy sand), 43–83 m depth.

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 6. Sphaerephesia hutchingsae n. sp., AM W. 42753 and AM W. 42734, scanning electron micrographs. A. Whole specimen, dorsal view, head on right end. External segmentation is evident (arrows). B. Whole specimen, dorsal view, with everted pharynx. C. Anterior end, dorsal view, showing head appendages and arrangement of tubercles and papillae on anterior chaetigers. D. Same, frontal view. E. First five chaetigers, lateral view, showing parapodia and lateral macrotubercles. F. Detail of macrotubercle chaetiger 5, with distal papilla. G. Mid-body parapodium, right side is anterior surface. H. Posterior parapodia, dorsal view. I. Mid-body parapodia and ventral body surface. J. First parapodium, anterior view. K. Chaetal fascicle, mid-body chaetiger. Abbreviations: al, acicular lobe; ap, antenniform papillae; 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.