Proeulepethus payungu, Woolley, Skipton & Wilson, Robin S., 2011

Woolley, Skipton & Wilson, Robin S., 2011, Two new species of Eulepethidae (Polychaeta) from Australian seas, Zootaxa 2839, pp. 47-66 : 60-61

Proeulepethus payungu sp. nov.

Figures 8–11

Material examined. Holotype: Australia: Western Australia (Indian Ocean coast): off Ningaloo South, Stn SS10/ 2005 146, 22 º4.767´S 113º47.767´E, 10 Jan 2005, 206– 201 m, beam trawl, MV F166646.

FIGURE 8. Proeulepethus payungu sp. nov., holotype MV F166646: A, Entire animal, dorsal view; B, 1st right elytron; C, 2nd left elytron; D, 8th left elytron; E, 12th left elytron.

Paratypes (2 specimens): Australia: Western Australia (Indian Ocean coast): off Ningaloo South, Stn SS10/ 2005 146, 22 º4.767´S 113º47.767´E, 10 Jan 2005, 206– 201 m, beam trawl [data as for holotype], 2 paratypes, MV F166647, MV F166649.

Description. Three specimens, all entire: Holotype 25 mm long, 4.8 mm wide including parapodia, 2.5 mm wide excluding parapodia, 36 segments. Two paratypes: 17, 20 mm long; 3.8, 4 mm wide including parapodia; 2.0, 2.7 mm wide excluding parapodia; 37, 39 segments. Elytrae 12 pairs on segments 2, 4, 5, 7, 9, 11, 13, 15, 17, 19, 21 and 24, becoming more elongate towards the posterior end (Figure 8A). All elytrae entire, without papillae or marginal fimbriae or notches, first and second pair irregular-ovoid and wider than long (Figures 8B, 8C), elytrae becoming more elongate posteriorly, elytrae 6 and 12 longer than wide (Figures 8D, 8E). Branchiae 10 pairs on segments 8, 10, 12, 14, 16, 18, 20, 22, 23, 25, replaced by fleshy lamellae on the 26th and following segments. Branchiae attached to the dorsal region of the parapodia, with dorsal and ventral ciliated bands, and distally attached branchial cirrus ( Figure 10 D). The lamellae are flattened triangles with rounded corners, widest near the base and nearly symmetrical, reducing in size posteriorly ( Figure 10 E).

Prostomium ( Figure 9 A) is barely visible beneath the elytrophores of segment 2, eyes absent. Median antenna conical, attached to the prostomium posterior to the attachment of the lateral antennae. Lateral antennae conical and longer than the median antenna and taper to a point. Palps conical and tapering and slightly longer than the first parapodium ( Figure 9 A).

Dorsal cirri present on posterior side of upper margin of parapodia 3 ( Figure 10 B) and 6. Ventral cirri of segment 2 asymmetrical, widest basally and taper to a fine tip ( Figure 10 A), on segment 3 ventral cirrus shorter with blunt tip and widest at about midpoint ( Figure 10 B), on median segments ovoid, articulated, with minute tip section ( Figure 10 C, D). Parapodia biramous, each ramus supported by a single amber aciculum, neuroaciculum expanded distally to form malleiform distal plates ( Figures 10 A–E). Notochaetae of anterior segments include dorsal bundle of amber serrate hooks with tapering tip and a few hooks with disciform tip ( Figure 11 B) and ventral bundle of fine capillaries which include smooth and finely spinous forms ( Figures 11 D, E). Notochaetae on posterior segments include dorsal bundle of amber serrate hooks with tapering tip ( Figure 11 G), hooks with disciform tip absent, hooks heavier and more numerous than on anterior segments. Ventral bundle of capillary notochaetae of posterior segments with both smooth and serrate forms similar to those of anterior segments. Neurochaetae similar throughout anterior and posterior segments and include an even array of bilimbate chaetae abruptly tapering to fine tips ( Figure 11 F) and non-limbate chaetae (‘acicular chaetae’ of Pettibone, 1969) with blunt tips ( Figure 11 A) and a single pectinate neurochaeta in dorsal-most position ( Figure 11 C).

Anal cirri broken on the holotype and on paratype MV F166649, paratype MV F166647 with left cirrus short and tapering, right cirrus about 3 times as long but apparently broken, available basal sections of all cirri smooth ( Figure 9 B).

Etymology. The species name payungu pays respect to the language group of the Aboriginal people whose traditional lands in northwestern Western Australia include that part of North-west Cape closest to where Proeulepethus payungu sp. nov. was collected.

Distribution and habitat. Proeulepethus payungu sp. nov. is known only from the Indian Ocean on the continental margin of Western Australia at about 22ºS at a depth of 206–211 metres.

Discussion. The genus Proeulepethus was erected by Pettibone (1986) to contain two species of Eulepethidae with elytral margins entire, lacking notches, papillae or fimbriae. Proeulepethus challengeriae ( McIntosh, 1885) is incompletely known, based on a single damaged anterior fragment and is here treated as Eulepethidae incertae sedis. Proeulepethus clarki Pettibone, 1986 is the remaining species and can be distinguished from Proeulepethus payungu sp. nov. as follows: In P.clarki the median antenna is about as long as the lateral antennae (although inserted more posteriorly) and the ventral palps are about twice the length of the first parapodium ( Pettibone, 1986 Figure 16A), and notochaetal hooks include blunt-tipped forms ( Pettibone, 1986 Figure 18C), whereas in Proeulepethus payungu sp. nov. the median antenna is slightly longer than the lateral antennae and the ventral palps are only slightly longer than the first parapodium, and blunt-tipped notochaetal hooks are absent.

Proeulepethus payungu sp. nov. is known only from the Indian Ocean on the continental margin of Western Australia while the other members of Proeulepethus Pettibone, 1986 , P.challengeriae and P.clarki , are only known from the Caribbean region. All known records of Proeulepethus species are from the depths of ~200–800 metres (other eulepethid genera are all known from much shallower depths) so the apparently disjunct distribution of the genus may simply reflect a relative lack of suitable samples at depths exceeding 200 m.

Figures

FIGURE 9. Proeulepethus payungu sp. nov., holotype MV F 166646: A, Head region and prostomium, first and second elytrae removed, dorsal view; Figure labels: Pa—palps; vTc—ventral tentactular cirrus; dTC; dorsal tentactular cirrus; MA—median antenna; LA—lateral antenna. B, Pygidium and final posterior segments, left and right cirrus present, ventral view.

FIGURE 10. Proeulepethus payungu sp. nov., holotype MV F 166646: A, parapodium segment 2, anterior view; B, parapodium segment 3, posterior view; C, parapodium segment 11, anterior view; D, branchial parapodium segment 14, anterior view; E, lamelligerous parapodium segment 26, anterior view.

FIGURE 11. Proeulepethus payungu sp. nov., holotype MV F 166646: A, neurochaeta from mid-fascicle segment 3; B, hooked upper notochaeta segment 11; C, pectinate neurochaeta segment 11; D, capillary notochaeta segment 14; E, capillary notochaeta segment 14; F, bilimbate neurochaeta segment 14; G, dorsal notochaeta segment 26.