Eunoe corbariae Suárez-Morales and Salazar-Vallejo, 2025

Eunoe corbariae Suárez-Morales and Salazar-Vallejo View in CoL sp. n.

( Figure 15 View Figure 15 )

Material examined

Holotype. Papua New Guinea. ( MNHN IA 2000-2122 About MNHN ), Expedition Papua Niugini, E Kotakot, RV Alis, Sta. CP 4039 ( 04° 18 ʹ 54.5976” S, 145° 37 ʹ 07.9716” E), 1000–1045 m, in sponges, 17 December 2017, S. Samadi, leg. GoogleMaps

Type locality

Papua New Guinea. E Kotakot, RV Alis, Sta . CP4039 ( 04°18 ʹ 54.5976” S, 145° 37 ʹ 07.9716” E), depth = 1000–1045 m.

Etymology

The specific epithet honours Dr Laure Corbari in recognition of her long-term efforts in organising scientific cruises for sampling tropical deep-sea benthos, including the cruise during which the holotype was collected, and because she has been very supportive of author SIS-V’s research activities for many years.

Diagnosis

Eunoe with cephalic peaks. Elytra without fimbriae, macrotubercles cylindrical, spread over elytral surface, microtubercles conical, tips brownish. Notochaetae straight, almost smooth. Neurochaetae of two types, upper neurochaetae terete, with series of distinct denticles, median and lower neurochaetae oar-shaped, almost smooth, straight, non-falcate.

Description of host

Holotype ( MNHN IA 2017–3996), complete, bent ventrally, most elytra and cephalic appendages detached ( Figure 15 View Figure 15 (A)), left elytron 8 and left parapodium of chaetiger 20 removed for observation (kept in container); body pale, middorsal region brownish along median region; one copepod parasite on dorsal side of left parapodium of chaetiger 27, and a detached egg mass in container, fixed under elytron; body 13 mm long, 3 mm wide, 41 chaetigers.

Prostomium subrectangular, slightly longer than wide, with cephalic peaks distinct ( Figure 9 View Figure 9 (B)). Anterior eyes dorsolateral, in widest prostomial area, 2 times as large as posterior ones. Median ceratostyle bent ventrally, thin, about as long as prostomium. Lateral ceratophores ventral, right ceratostyle lost, left one third as large as median ceratostyle, tip thin, long. Left palp massive, about 3 times as long as wide, blunt, right palp lost. Facial tubercle pale, not visible dorsally.

Tentacular segment without cirri; left cirrophores with a single chaeta. Second chaetiger without nuchal hood; left ventral cirrus slightly longer than following ones. Nephridial papillae cylindrical, blunt, along chaetigers 3–36. Pharynx not exposed.

Elytra thin, whitish, non-fimbriate ( Figure 15 View Figure 15 (C)), with macrotubercles cylindrical, blunt, transparent, spread over elytral surface; microtubercles present along median and posterior elytral surface, each conical, tips brownish ( Figure 15 View Figure 15 (D, E)). Insertion area with similar density and size of microtubercles than adjacent regions.

Parapodia biramous ( Figure 15 View Figure 15 (F)). Dorsal cirri tapered, not swollen subdistally, surface papillate, tip thin, one-fourth as long as cirrostyle. Notopodium with acicular lobe projected. Notochaetae coarser than neurochaetae, abundant, upper ones directed dorsally,median and lower ones directed laterally, of a single type, straight or slightly bent, with indistinct denticulation, tips entire (inset in Figure 15 View Figure 15 (G)). Neuropodium larger than notopodium, with very long acicular lobe, tip sometimes directed dorsally. Neurochaetae golden abundant, of two types, upper ones terete, with series of denticles along median region, tip entire, median and lower ones oar-shaped, with indistinct denticulation, tips entire, non-falcate ( Figure 9 View Figure 9 (H)). Ventral cirri thin, tapered.

Posterior region tapered ( Figure 15 View Figure 15 (I)); pygidium with anus terminal, slightly prolapsed, anal cirri lost.

Remarks

Eunoe corbariae sp. n. is unique among Eunoe species because it has two types of neurochaetae: the most abundant ones are oar-shaped, smooth or very finely denticulate along margins, and two superior chaetae provided with series of fine denticulations leaving smooth the distal part.

In the key to Eunoe species by Uschakov (1982), the only species with fine denticulation along chaetae is the subarctic E. bathydromus (Ditlevsen, 1917) , but E. corbariae differs from it because its elytra do not have large globular processes along posterior elytral half, which are distinctive in E. bathydromus .

Uschakov (1982, pp. 353–354) compared E. bathydromus with other species having small denticulation along chaetae, and they differ from E. corbariae as follows. Eunoe opalina M’Intosh, 1885 , described from the Strait of Magellan, has elytra without large globular processes (absent in E. corbariae ), and neurochaetae with tips markedly falcate, and not tapered like in E. corbariae . Eunoe corbariae also differs from E. caeca Moore, 1910 , described from the Northern Pacific, by having eyes, a very long neuracicular lobe (compared with a short one), and by having straight neurochaetae (compared with being distally falcate). The last species included by Uschakov was E. laetmogonensis Kirkegaard and Billet, 1980 , described from off Ireland and NW Africa, which also has falcate neurochaetae.

In contrast, E. corbariae also differs from E. kermadeca Kirkegaard, 1995 , because the latter has shorter, straight neuracicular lobes and falcate, sharp neurochaetae, whereas neuracicular lobes are longer and rectangular in E. corbariae , and its neurochaetae are straight.

Distribution

Only known from off Madang, Papua New Guinea, in sediments with sponges at 1000– 1045 m water depth .