Marphysa bifurcata Kott 1951
Creators: name: Zanol, Joana
name: Da Silva, Thauane Dos S. C.
name: Hutchings, Pat
Publisher: name: Zenodo
Year: 2017
Subjects: Biodiversity
Taxonomy
Animalia
Annelida
Polychaeta
Eunicida
Eunicidae
Marphysa
Marphysa bifurcata

description: Marphysa bifurcata Kott, 1951
(Figs 1, 2)
Marphysa bifurcata Kott, 1951: 112 –123.— Day 1967: 397 –398.— Gallardo 1968: 80.— Joydas et al. 2012: 330.
Material Examined. HOLOTYPE: Australia, Western Australia, Point Peron, 25° 51' S, 113° 34' E, 1946, (AM W.6820) fixed in formalin. Non-types: Australia, Queensland, Lizard Island, off Casuarina Beach, 14° 40' 46" S, 145° 26' 49" E, Aug 17, 2013, AM W.44353 (1 incomplete specimen), AM W.44391 (1 complete and 2 incomplete specimens), fixed in formalin; Aug 20, 2013, AM W.44633 (1 complete and 2 incomplete specimens), fixed in formalin; Aug 21, 2013, AM W.44920 (3 complete and 1 incomplete specimens), AM W.44911 (1 complete and 1 incomplete specimens), fixed in formalin; north west of Watson's Bay, 14° 39' 41" S, 145° 22' 27" E, Aug 23, 2013, AM W.44977 (3 incomplete specimens), AM W.44983 (3 incomplete specimens) fixed in formalin and AM W.44982 (1 incomplete specimen) fixed in ethanol.
Measurements. Holotype incomplete with 163 chaetigers, 53 mm in total length, 5 mm in length through chaetiger 10 and 3 mm wide at this chaetiger with parapodia. Non-types, six complete specimens ranging from 96– 150 chaetigers, 23–45 mm in total length, 2–4.4 mm in length through chaetiger 10 and 1.36–1.92 mm wide at this chaetiger with parapodia; 14 incomplete specimens ranging from 26–148 chaetigers, 10–45 mm in total length, 2.25–5.4 mm in length through chaetiger 10 and 0.68– 3 mm wide at this chaetiger with parapodia.
Description. Live specimens translucent with reddish hues due to blood (Fig. 1 A). Fixed specimens beige to brown in color (Fig. 1 B–E).
Body long and slender, widest at anterior region, evenly tapering towards posterior end; cross section dorsally flattened and ventrally slightly rounded at anterior and median regions, flattened to round at posterior region of body. Chaetigers less than 10 times wider than long at widest region of body.
Prostomium approximately as long as, half as deep as and narrower to as wide as peristomium; dorsally flat with anterior end higher (Fig. 1 B, C, D), anteriorly rounded to tapering; not bilobed; median sulcus absent (Fig. 1 C) or inconspicuous (Fig. 1 B) at anterior end, absent at dorsal side and conspicuously present at ventral side (Fig. 1 E).
Prostomial appendages short, reaching around one third length of prostomium. Median and lateral antennae in straight line, palps inserted slightly more anteriorly (Fig. 1 B, C). Median antenna longest prostomial appendage; isolated by gap from lateral antennae and palps. Antennal styles and palpostyles tapering to fusiform and wrinkled under light microscope. Antennophores and palpophores ring shaped. One pair of eyes present, conspicuous in shape of dark line between lateral antennae antennophore and palpophore (Fig. 1 D).
Separation between peristomial rings distinct all around. Second peristomial ring about as long as 1/5–1/3 of complete peristomium. Peristomial ventro-lateral lips distinct laterally as elevated surface (Fig. 1 D). Peristomial anterior margin of dorsal and ventral sides in shallow arc, lateral margins longer; shortest on dorsal side (Fig. 1 E).
Posterior end of muscularized pharynx at chaetiger 3–5. Mandibles with small delicate cutting plates, diamond to oval shape, some with medio-anterior teeth (Fig. 1 F, G). MxI around twice as long as carriers and 6–8 times longer than locking system (Fig. 1 H, I). MxIII at least in part located ventral to MxII,; attachment lamella oval to rectangular present only at anterior end of median margin of MxIII (Fig. 1 I). Left MxIV wider than long, semicircular; attachment lamella shorter than plate, almost as wide as plate, along most of anterior edge, missing on lateral edge of plate (Fig. 1 I, J). Right MxIV attachment lamella starting between lateralmost teeth 1–2, along around ¾ of plate, longest at lateral side and evenly shorter towards opposite side (Fig. 1 I, K). Maxillary formula: I= 1+1, II=5 (4)+6 (5), III= 6 (5, 7)+0, IV=5 (4, 6)+8 (7–10), V= 1+1, VI absent.
Pre-neurochaetal lobe shorter than neurochaetal lobe along whole body. Post-neurochaetal lobe longer than neurochaetal lobe in anterior chaetigers decreasing in length along body, becoming as long as or shorter than neurochaetal lobe in median and posterior chaetigers; in anterior chaetigers wide, distally truncate with longer dorsal edge (Fig. 2 A, B). Neurochaetal lobe rounded in anterior (Fig. 2 A), tapering in median and posterior chaetigers (Fig. 2 C). Anterior notopodial cirri evenly tapering; from around start of branchiae to end of body some abruptly tapering. Abruptly tapering notopodial cirri vary from simple (Fig. 2 A–C), semi-bifurcated (Fig. 2 D) to bifurcated (Fig. 2 E–G), not consistently present in all chaetigers. Notopodial cirri longer than neurochaetal lobe in anterior chaetigers (Fig. 2 A, B), decreasing in length towards posterior region, about as long as neurochaetal lobe along most of body (Fig. 2 C). Anteriormost ventral cirri digitiform to tapering; basally inflated from chaetiger 4-6 until end of body; inflated base round shaped (Fig. 2 A) with rounded tip conspicuous from chaetiger 8 to end of body; inflated base gradually decreasing in size from around chaetigers 21 to 50; rounded tip gradually increasing in length along body. Ventral cirri as long as or longer than neurochaetal lobe at anterior region (Fig. 2 A), slightly shorter to as long as neurochaetal lobe at median and posterior region (Fig. 2 C), sometimes longer than neurochaetal lobe in posteriormost chaetigers.
Branchiae palmate present along most of body, with one filament from chaetiger 16–24, reaching maximum of 2–4 filaments at chaetiger 21–62; where best developed, branchial filaments around 2–8 and 4–6 times longer, respectively, than branchial stems and notopodial cirri; length of filaments start to decrease around chaetiger 61– 82. Branchial stems completely attached to body wall (Fig. 2 B, E, F).
Notopodial aciculae yellow, present in notopodial cirri along whole body (Fig. 2 F). Neurochaetae in two distinct bundles; supra-acicular with limbate chaetae and pectinate chaetae, subacicular with bidentate compound falcigers chaetae and subacicular hooks. Neuroaciculae tip blunt to tapering, brown to yellow until first quarter of body, thereafter only yellow; distributed in oblique row, anteriormost neuroaciculae also dorsalmost in parapodium. Number of neuroaciculae decreasing towards posterior end, 2–4 in anteriormost chaetigers, two in first quarter of body and thereafter only one; distributed from median to dorsal region of neurochaetal lobe in most anterior parapodia (P1) and midline thereafter. Number of limbate chaetae and compound falcigers chaetae also varying along body. Limbate chaetae longer than all other chaetae, serrated, narrowing towards posterior end (Fig. 2 H); around 8–18 limbate in anterior region, 3–7 in median and 6–11 in posterior. Compound falciger chaetae around 14–26 in anteriormost chaetigers (P1), 9–14 in first quarter, 3–6 in the remaining part of body. Shaft and appendage of compound falciger chaetae marginally serrated; appendage bidentate with guards symmetrically blunt without mucros; both teeth directed laterally; distal tooth tapering and curved; proximal tooth perpendicular to length of chaetae, as long as or longer than distal tooth (Fig. 2 J). One–three thin pectinate chaetae with around 10–22 teeth present at anteroventral edge of supra-acicular bundle until second quarter of body (P3); inner teeth long, equal in length, evenly tapering; outer teeth not equal in length and longer than inner teeth, longest about twice as long as inner teeth (Fig. 2 K, L). Curved thick pectinate chaetae present in median (P3–P4) to posterior regions with around 10–14 coarse teeth, all with about same length at distal end but with increasingly deeper proximal ends from margins to center, teeth with deepest proximal end off center (Fig. 2 M); 1-3 thick pectinate per parapodium present until end of body. Pseudocompound chaetae and compound spinigers chaetae absent. Subacicular hooks first present from chaetiger 20–32, present in all chaetigers thereafter, always single; guards not always present (Fig. 2 N–R); hook light yellow to brown, bidentate, narrower or as wide as aciculae; distal tooth rounded to tapering, shorter than proximal tooth, erect (Fig. 2 N–Q) to curved (Fig. 2 R); proximal tooth about twice as long as distal tooth, perpendicular to length of hook or directed distally, rounded or tapering (Fig. 2 N–R).
Pygidium longer on ventral side, with two pairs of pygidial cirri attached to ventral margin; pygidial cirri tapering with irregular cylindrical articulations, dorsal 2–4 times longer than ventral cirri.
Variation. In some specimens jaws are semi-everted which make prostomium seem shorter and less deep than in those with jaws withdrawn. Eyes are absent in the holotype, this could be due to preservation. The most conspicuously variable feature among examined specimens is the shape of notopodial cirri. They can be simple, semi-bifurcated or bifurcated. All examined specimens have simple notopodial cirri in anteriormost chaetigers. The two largest specimens examined (AM W.6820 and AM W.44977) have bifurcated notopodial cirri along most of the examined fragments. The remaining specimens have semi-bifurcate cirri, which may be irregularly distributed along the body. Almost all specimens have abruptly tapering notopodial cirri at least in some chaetigers. Number of limbate chaetae decreases towards median region but in some cases increases in posteriormost chaetigers. Thin pectinate chaetae have more teeth in the longest specimen examined (AM W.44977) than in the other specimens. Laterally directed proximal teeth of subacicular hooks are usually present in posteriormost chaetigers. Subacicular hooks with smaller teeth may be worn down or characteristic of larger specimens (e.g., AM W.6820 and AM W.44977).
Remarks. Our description complements the original one by Kott (1951) in describing features not mentioned and including comments about variations occurring along the body and intraspecific variation as exhibited by the additional material examined. The main additional features observed in our study are the shape of notopodial cirri, pectinate chaetae and subacicular hooks.. Notopodial cirri may not be completely bifurcated, the semi-bifurcated shape is the most common among the studied specimens. In the original description, pectinate chaetae were described only as pectinate of general type, whereas we refer to it as a thin pectinate. We found two types of pectinate chaetae, thin and thick. Thick pectinate chaetae are restricted to the posterior region, which is absent in the incomplete holotype.
Marphysa bifurcata is morphologically close to Marphysa mortenseni Monro, 1928 described from Panama. They share prostomium not bilobed, very short prostomial appendages and bifurcated notopodial cirri. However, M. mortenseni has a more rounded and shorter prostomium and loose branchial stems.
Habitat. Intertidal to 15 m deep, limestone reef and sand.
Distribution. Australia: Western Australia, Queensland (Lizard Island). Arabian Gulf: Saudi Arabia coast (Joydas et al. 2012). South Vietnam: Bay of Nha Trang (Gallardo 1968). Indian Ocean: Mozambique (Day 1967).
description: Published as part of Zanol, Joana, Da Silva, Thauane Dos S. C. & Hutchings, Pat, 2017, One new species and two redescriptions of Marphysa (Eunicidae, Annelida) species of the Aenea-group from Australia, pp. 411-426 in Zootaxa 4268 (3) on pages 413-417, DOI: 10.11646/zootaxa.4268.3.6, http://zenodo.org/record/580536