Ephesiella australiensis Hartmann-Schröder, 1982

Capa, María & Rouse, Greg W., 2015, Sphaerodoridae (Annelida) from Lizard Island, Great Barrier Reef, Australia, including the description of two new species and reproductive notes, Zootaxa 4019 (1), pp. 168-183 : 170-172

Ephesiella australiensis Hartmann-Schröder, 1982

( Figs 1 , 2 A, B)

Ephesiella australiensis Hartmann-Schröder, 1982: 80 –81, figs 84–87.

Type material. Holotype: ZMH P.16773, Cervantes, Western Australia, Australia, sandy beach among Posidonia , 24 Oct 1975. Paratype: AM W.42693 (on SEM stub), Lizard Island, between South Island and Palfrey Island, 14°41'54"S, 145°26'45"E, dead coral, 17 m, 31 Mar 1995.

Other material examined. AM W.42702 (2, 1 on SEM stub), Western Australia, south west Enderby Island, 20°37'18"S, 116°27'23"E, dead coral encrusted with bryozoans, ascidians and bivalves, 14 m, 8 Aug 2000; AM W.42688 (on SEM stub), Australia, New South Wales, Cape Three Points, south-east of Third Point, 33°31'55"S, 151°24'58"E, sand from around large boulders at edge of rocky reef, 30 m, 6 May 2007.

Diagnosis. Body long and slender. Two longitudinal rows of macrotubercles, one pair per segment, may be absent in first chaetiger. Macrotubercles spherical, sessile, with terminal papillae. Two longitudinal rows of microtubercles, with a collar and a terminal papillae, one pair per segment, running parallel between macrotubercles. Additionally, papillae arranged in three transverse rows on dorsum and in 4–5 transverse rows on ventrum. Head appendages digitiform. Mid-body parapodia with six semi-spherical papillae, all similar in size: one anterior dorsal, one anterior, near the acicular lobe, one anterior ventral two posterior-dorsal, one of the latter distal. Parapodia from chaetiger 2 with compound or semi-compound, shaft provided with a distal spine; hooks not observed.

Description. (of Lizard Island specimen) Body elongate, measuring 4.2 mm long, 0.4 mm wide, with 63 segments, slightly narrowing along posterior segments ( Fig. 1 A). Sub-quadrangular in section, with convex dorsum ( Fig. 1 A). Tegument with transverse wrinkles and segmentation inconspicuous ( Fig. 1 A). Preserved material lacking pigmentation. Head externally indistinct. Anterior end bluntly rounded and damaged. Prostomium with five appendages; paired palps and lateral antennae digitiform and three times longer than wide; median antenna, shorter, hemispherical. Prostomial papillae, present but numbers uncertain. Tentacular cirri slightly shorter than palps and lateral antennae. First chaetiger with two sessile and spherical macrotubercles, each provided with a digitiform terminal papillae; microtubercles absent. Rest of chaetigers with two macrotubercles each, arranged in two longitudinal dorso-lateral rows, shape and size of all macrotubercles similar, slightly increasing in size in first segments, and decreasing posteriorly ( Fig. 1 A–D). A pair of microtubercles on each segment from chaetiger to until last segment, running in two longitudinal rows inside macrotubercles; with terminal papillae longer than collar ( Fig. 1 C). Spherical and elliptical papillae present over dorsum, arranged in three transverse rows per segment, with around 15–20 papillae per segment on mid body region, including 2–3 papillae between macrotubercles and parapodia ( Figs 1 A, 2B). Ventral surface with spherical papillae, arranged in 4–5 transverse rows (seemingly a zig-zag in anterio-posterior view), with a total of 20–25 per segment, in mid-body; numbers decreasing towards posterior end. Parapodia sub-conical, increasing in size towards chaetiger 3 and as longer as wide ( Fig. 1 C–E). Acicular lobe projecting distally anterior to chaetae, resembling other parapodial papillae or slightly longer ( Fig. 1 E). Ventral cirri bottle-shaped similar in length to acicular lobe ( Fig. 1 E). Anterior parapodia with four hemispherical papillae: one anterior, one anterio-ventral, one anterior-dorsal and one posterior, in addition to the acicular lobe. Mid-body parapodia with six semi-spherical papillae, all similar in size: one anterior dorsal, one anterior, near the acicular lobe, one anterior ventral, two posterior-dorsal, one of the latter distal ( Figs 1 D–E, 2B). Compound chaetae, appearing as semi-compound in some chaetigers, arranged in a curved transverse rows around acicular lobe and numbering 4–6 per fascicle ( Fig. 1 G–I). First chaetiger with blades 5–6 times longer than wide and conspicuous serration along cutting edge. Hooks not seen. Chaetae from chaetiger 3 with shaft distally enlarged and serrated with a main distal tooth; blades showing a slight dorso-ventral gradation (1–2 times longer than wide; except for anterior chaetiger with longer blades) recurved and with smooth or few serration of the cutting edge ( Fig. 1 G–I). Pygidium terminal, with mid-ventral digitiform anal cirrus and a pair of dorsal anal cirri, similar in shape but slightly smaller than macrotubercles ( Fig. 1 F). Eyes, muscular pharynx, gonads, gametes or copulatory organs not observed.

Remarks. Ephesiella is a cosmopolitan genus that requires revision. It currently groups 15 species supposedly sharing the presence of only compound chaetae from chaetiger 2. Nevertheless, some species have been described as bearing semi-compound chaetae (e.g., Moore 1909, and description above), a feature half way to members of Sphaerodorum (with only simple chaetae) and Ephesiopsis (with both simple and compound chaetae in all parapodia). Moreover, several species have been described from a single or few specimens (e.g., Desbruyères 1980; Hartmann-Schröder 1982) and consequently, the intraspecific variation has not been addressed. Most specific diagnostic characters rely on the absence or presence of hooks, the number of prostomial appendages, the number and arrangement of parapodial papillae. The types and specimens examined for this study (cited above) all appear to: i) lack hooks and antenniform papillae; ii) have the median antenna distinctly shorter than other prostomial appendages; iii) have three transverse rows of dorsal papillae per chaetiger; iv) number of parapodial papillae range between 4–7; v) bear compound, or semi-compound, chaetae with short blades (2–3 times longer than wide), most of them provided with a distinct spine on the tip of the shaft (not observed in the types, due to their fragile condition for manipulation). Most specimens examined from other Australian localities do share these morphological traits. However, some specimens showed different chaetal morphology (longer blades and/or distal tooth in shaft absent), or different relative position of the macro and microtubercles (Capa & Bakken 2015). Ephesiella australiensis is represented elsewhere in Queensland, but only reported from Townsville (Capa & Bakken 2015).

Figures

FIGURE 1. Ephesiella australiensis SEM images, AM W. 42693. A. Whole specimen, anterior end on top; B. Anterior chaetigers, ventro-lateral view, showing microtubercle (mi), macrotubercles (mt) and parapodia (par) with bottle-shaped ventral cirrus and parapodial papillae (pp); C. Same from a dorsal view; D. Mid-chaetiger with macrotubercle (mt) with terminal papillae, and contracted parapodium bearing at least six papillae (arrowheads); E. Mid-body parapodium, anterior view, with five spherical papillae (arrowheads), five compound chaetae and a bottle-shaped ventral cirrus; F. Posterior end showing two terminal macrotubercles, and a digitiform ventral cirrus; G. Compound chaetae of anterior chaetiger; H. Chaetae of mid-body chaetiger; I. Detail of chaetae from posterior chaetiger showing the blade, almost fused to the shaft and the characteristic spinulation of the shaft with a distal-most thicker spine (arrow).

FIGURE 2. Stylised drawings. A, B. Ephesiella australiensis. A. Dorsal tubercles of chaetigers 11 – 14; B. Parapodial papillae and appendages including ventral cirrus, acicular lobe, papillae and nearby macrotubercle; the concentric circles represent the volume of the parapodium (larger ones indicate basal and smaller distal areas) and the red axis its four sides; C, D. Sphaerodoropsis auranticus n. sp.; C. Dorsal tubercles of chaetigers 11 – 14, and pigmentation pattern; D. Arrangement of parapodial appendages and papillae; E, F. Sphaerodoropsis plurituberculata n. sp.; E. Dorsal tubercles of chaetigers 11 – 14; F. Arrangement of parapodial appendages and papillae.