Ophryotrocha shieldsi, Paxton, Hannelore & Davey, Adam, 2010

Paxton, Hannelore & Davey, Adam, 2010, A new species of Ophryotrocha (Annelida: Dorvilleidae) associated with fish farming at Macquarie Harbour, Tasmania, Australia, Zootaxa 2509, pp. 53-61 : 55-56

publication ID	https://doi.org/ 10.5281/zenodo.196027
DOI	https://doi.org/10.5281/zenodo.6212083
persistent identifier	https://treatment.plazi.org/id/337AED51-FFC8-FFB9-42C6-4771CB3EF850
treatment provided by	Plazi
scientific name	Ophryotrocha shieldsi
status	sp. nov.

Treatment

Ophryotrocha shieldsi View in CoL , sp. nov.

Figs. 1–3 View FIGURE 1 View FIGURE 2 View FIGURE 3

Material examined. Type material: Liberty Point, Macquarie Harbour, Tasmania, 42º18’17.21063”S; 145º19’14.60318”E, beneath sea cages, 20 m, SCUBA diving, February 2002, collectors A. Davey, J. Lane, D. Shields, holotype (AM W.36644), 10 paratypes (AM W.36645); same locality and collectors, 20 m, modified ROV, 4 February 2009, 20 paratypes (AM W.36646). DNA voucher specimen: Same locality and collectors, 4 February 2009 ( GNM Polychaeta 13224).

Description. Live specimens up to 16 mm long for 46 chaetigers. Length of holotype 7.3 mm for 43 chaetigers (paratypes 2.5–6.0 mm for 29–36 chaetigers), width of holotype 0.9 mm including dorsal lateral lobes at chaetiger 10 (paratypes 0.3–0.7 mm). Live specimens with striking colour pattern of salmon pink pigmentation on peristomial rings and lateral segmental lobes, body otherwise whitish. Preserved specimens opaque white. Body long, slender, slightly tapering towards posterior end, dorsal side convex, ventral side slightly concave ( Fig. 2 View FIGURE 2 A, C). Prostomium ( Figs. 2 View FIGURE 2 B, 3A) with ciliary ring in front of antennae, continuous across palpophores, additional incomplete band dorsally behind antennae and ventrally in front and behind ciliary ring ( Figs. 2 View FIGURE 2 C, 3B); peristomial rings and chaetigerous segments encircled by ciliary rings, continuous across lateral dorsal and ventral lobes.

Prostomium about twice as wide as long, bearing pair of dorsolateral cirriform antennae and pair of ventrolateral biarticulate palps. Palps consisting of large palpophore and small globular palpostyle. Pair of oval slanted eyes ( Fig. 3 View FIGURE 3 A) at centre of posterior edge of prostomium, posteriorly almost touching, anteriorly further apart. Eyes internal, light-reflecting structures, appearing silvery white in live animals under incident light but invisible in preserved specimens. Nuchal organs at level of eyes, two at either side of eyes. Peristomium represented by 2 apodous achaetous rings, similar in length to following chaetigers.

Chaetigers with well developed parapodia and prominent dorsal and ventral lateral lobes. Dorsal lobes ( Figs. 2 View FIGURE 2 A, 3A, C) ovate, cushion-like, ventral lobes ( Figs. 2 View FIGURE 2 C, 3B) digitate to triangular; lobes present on all chaetigers but best developed in middle body region. Parapodia ( Fig. 2 View FIGURE 2 D, 3D) uniramous, long and slender, distally dilating, bearing dorsal and ventral cirrus and acicular lobe; each structure digitate, about as long as median width of parapodium. Parapodia supported by acicula, terminating in acicular lobe and subacicular short simple chaeta or accessory acicula, emerging from ventral chaetal lobe; chaetal lobe in most cases completely retracted ( Fig. 2 View FIGURE 2 D, E) or expanded to triangular lobe ( Fig. 3 View FIGURE 3 D). Chaetae long and very thin ( Fig. 2 View FIGURE 2 E); supra-acicular fascicle with 5-8 simple spatulate chaetae ( Fig. 3 View FIGURE 3 E), subacicular fascicle with 5-7 heterogomph falcigers ( Fig. 3 View FIGURE 3 F); upper part of simple chaetae and appendage of falcigers minutely serrated, with blunt tip; shaft of falciger minutely serrated. Pygidium wider than long, with pair of digitate pygidial cirri; anus dorsal ( Fig. 3 View FIGURE 3 C). Mature males with rosette glands, paired dorsal segmental glandular structures on posterior half of body ( Figs. 2 View FIGURE 2 F, 3C). Structures consisting of circular clusters of large cells with perforated integument ( Fig. 2 View FIGURE 2 G) (for discussion of rosette glands see Paxton & Åkesson 2007).

Mandibles strongly sclerotised, black; consisting of two elongate shafts widening to distal cutting plates with slightly curved anterior edge with medial roundish protrusion and 13–16 conical teeth ( Fig. 3 View FIGURE 3 G). Maxillary apparatus of P- and K-type; maxillae consisting of forceps fused with carrier-like structure and 7 pairs of anterior denticles (D). P-type maxillae occurring in females and immature males, weakly sclerotised with serrated ridges slightly darker ( Figs. 2 View FIGURE 2 H, 3H). P-forceps with two transverse ridges, each with about 30 alternating larger and smaller teeth and a large fang. Denticles 1–3 similar to ridges of forceps with alternating large and small teeth and fang, D4–7 more delicate, with very finely serrated edge. K-type maxillae only in mature males, darkly sclerotised, almost black ( Fig. 3 View FIGURE 3 I). K-forceps smooth, distally falcate. Denticles attached by ligament strut to forceps; serration of denticles similar to P-type but with fewer teeth.

Etymology. The new species is named in honour of Derek Shields, who originally observed the aggregations of the new species, and encouraged the second author to study these animals.

Remarks. The new species is the fourth species of the O. lobifera group. Like O. lobifera it has cushionlike lateral lobes. However, in O. lobifera the dorsal lobes are triangular, while in O. shieldsi they are ovate. Other differences are: O. shieldsi has palps with small globular rather than longer digitate palpostyles, Pmaxillae with forceps and denticles serrated by alternating large and small teeth rather than uniform teeth, and mandibles with curved rather than straight anterior edge. Ophryotrocha lipovskyae and O. craigsmithi differ from both species by possessing lamella-like lateral dorsal lobes. Analysis of DNA sequences of the mitochondrial CO1 and ribosomal 16S genes has demonstrated that O. shieldsi is sufficiently genetically isolated from the other three species to warrant specific status (Helena Wiklund, personal communication 2009). Accession numbers for DNA sequences from O. shieldsi , published on GenBank: HM181931 View Materials (CO1), HM181932 View Materials (16S).