Prionospio amarsupiata, Paterson, Gordon L. J., Neal, Lenka, Altamira, Iris, Soto, Eulogio H., Smith, Craig R., Menot, Lenaick, Billett, David S. M., Cunha, Marina R., Marchais-Laguionie, Claire & Glover, Adrian G., 2016

Paterson, Gordon L. J., Neal, Lenka, Altamira, Iris, Soto, Eulogio H., Smith, Craig R., Menot, Lenaick, Billett, David S. M., Cunha, Marina R., Marchais-Laguionie, Claire & Glover, Adrian G., 2016, New Prionospio and Aurospio Species from the Deep Sea (Annelida: Polychaeta), Zootaxa 4092 (1) : 5-8

Prionospio amarsupiata sp. nov. Neal & Altamira

( Figures 1 , 2.1, 3, 8e)

Prionospio sp D Paterson et al. 2011: 2453.

Material examined. 24 specimens examined.

Holotype: Setúbal canyon RRS Charles Darwin 179. April–May 2006, St. 56842#1, 38º06.45’N 9º59.94’W, 4482 m (NHMUK 2015:1042).

Paratypes: Portuguese margin canyons: Nazaré canyon RRS Discovery 297, August 2005, St. 15758#2, 39º34.94’ N 10º19.00’ W, 4332 m, 2 individuals; St. 15765#2, 39º35.00’ N, 10º19.04’ W, 4336 m, 1 individual.

RRS Charles Darwin 179, April–May 2006, St. 56861#1 39º35.57’ N, 10º20.02’ W, 4404 m, 1 individual. St. 56847#6 39°35.57’N 10°19.99’W 4403m, 1 individual.

Setúbal canyon RRS Charles Darwin 179. April–May 2006, St. 56804#5, 38º09.27’N 9º36.93’W, 3275m, 1 individual; St. 56804#6 38º09.26’N 9º36.94’W, 3275m, 3 individuals; St. 56806#1, 38º09.29’N 9º36.96’W, 3275m, 1 individual; St. 56838#2 38º06.50’N 9º59.98’W, 4482m, 1 individual; St. 56842#1, 38º06.45’ºN 9º59.94’W, 4482m, 3 individuals;

Cascais canyon RRS Charles Darwin 179. April–May 2006, St. 56837#8, 38º22.49’N 9º 53.52ºW, 4244 m, 1 individual; St. 56821#1, 38º17.96’N 9º46.87’ºW, 3219m, 1 individual; St. 56823#2, 38º18.01’N 9º47.02’ºW, 3218m, 1 individual; St. 56828#1, 38º18.02’N 9º46.98’W, 3199m, 1 individual.

Other material studied: Crozet Island RRS Discovery D300, December 2005 – January 2006, site M6,15773#31, 49°01.92’S 51°13.88’E, 4192 m, 1 individual. Site M5, 15773#18, 45°52.96’ S, 56°23.78’ E, 4186 m, 1 individual.

Kaplan CCFZ Central Site (IFREMER Nodinaut campaign): RV L’Atalante, May–June 2004 KAP3, CRS868/ MTB9, 14°3.093’N, 130°4.7825’W, 5031m, individual KP397, 1 individual.

EqPac: RV Thomas Thompson, November 1992, BC15, 5°N 140 W, 0-1cm, EP436 1 individual

Madeira Abyssal Plain: RRS Discovery, August 1990, 12174 3-5cm, 300µm: (MAST_Polychaete Intercalibration Project number–map 55), 1 individual.

Cape Verde Abyssal Plain: RRS Discovery, October 1993, 12600#10 213.2’N 3111.0’W, 4543 m, MAST_cv7, 1 individual.

Diagnostic features. Lack of interparapodial pouches, first branchial pair with only few pinnules at the base of branchiae.

Description. Holotype incomplete with 42 segments, measuring 14.5 mm long for 42 chaetigers and 0.63 mm wide at chaetiger 1. Pale yellow colour in alcohol. Prostomium angular, bottle-shaped with broadly rounded anterior margin, prostomial peaks normally absent (but two small peaks observed in one of the CROZET specimens); slender caruncle extending to anterior margin of chaetiger 2 ( Fig.3 a); eyes not observed. Peristomium well developed, encircling prostomium closely like a collar, partially fused to chaetiger 1, forming low lateral wings ( Fig3 .a).

Four pairs of branchiae present on chaetigers 2–5. First pair longest, reaching to chaetiger 10, very slender and cylindrical, although slightly flattened near base and with slender, slightly curled tips; surface mostly smooth to slightly wrinkled (Fig.2.1a); very few (1–3) pinnules near base; fourth pair of branchiae similar to first pair but about half the length, apinnate, no rudimentary pinnules observed. Branchial pairs 2 and 3 short, fleshy, foliaceous, wider at base, tapering into somewhat swollen tip, laterally ciliated, both pairs slightly shorter than accompanying notopodial lamellae, in dorsal view both pairs covered by enlarged notopodial lamellae. All branchial pairs situated lateral and slightly posterior to notopodial lamellae.

Anterior notopodial lamellae from chaetiger 2–20 (holotype) generally enlarged, subtriangular, largest on branchial segments, particularly on chaetigers 3 and 4; more narrow on chaetiger 5; from chaetiger 6 increasing in width, becoming nearly square by chaetiger 10; after chaetiger 20 greatly reduced in size, becoming flattened assuming broadly ovoid shape with sharp pointed dorsal end and broad round posterior ventral end (Fig. 2.1e chaetiger 22). Dorsal crests on chaetigers 5–20.

Neuropodial lamellae small on chaetiger 1, largest on branchial chaetigers, then gradually becoming reduced in size; lamellae on chaetiger 2 fan-shaped with rounded corners (Fig 2.1a); lamellae on chaetiger 3 also fan-like possesing well developed ventral tip (Fig. 2.1b); lamellae on chaetiger 4 rounded; lamellae on cheatiger 5 low, rectangular (Fig. 2.1c); from chaetiger 6 more rounded ventrally, starting to assume broadly ovoid in shape with somewhat pointed ventral tip ( Fig.2 e–f); similarly shaped through chaetiger 42, with lamellae becoming more flattened and pointed both dorsally and ventrally (Fig. 2.1f). Interparapodial pouches absent ( Fig.3 b).

Notopodia in anterior region with four rows of dense, yellow-hued capillaries, anterior neuropodial capillaries arranged in two rows. Sabre chaetae and neuropodial hooks start on chaetiger 19 in holotype and other specimens of similar size, but on chaetiger 18 in smaller specimens. Sabre chaetae long, slender, gently curved, often broken; anterior half is lightly granulated; 1 to 2 per fascicle. Neuropodial hooks up to 10 per fascicle. Neuropodial hooks long, slender, with round, inflated primary hood and striated secondary hood; shaft very constricted just below multidentate head, with six pairs of small teeth above the main fang ( Fig.3 c,d). Notopodial hooks not present in 42 chaetigers. Pygidium unknown.

Methyl green pattern. Prostomium, peristomium and the edge of notopodial and neuropodial lamellae on chaetiger 1–4 stained strongly, thereafter only edges of notopodial lamellae and dorsal crest with faint stain.

Remarks. This species closely resembles Prionospio ehlersi Fauvel, 1928 in the shape of the prostomium and peristomium and the chaetiger where the sabre chaetae and neuropodial hooks appear; neuropodial hooded hooks and sabre chaetae begin on chaetigers 18–19 in P. amarsupiata sp. nov., which is within the range of their occurrence on chaetigers 18–22 in P. ehlersi . The major difference is in the small number of pinnules on first branchial pair and lack of pouches in Prionospio amarsupiata sp. nov. This feature has been encountered in specimens collected from Crozet as well as in Portuguese canyons, EqPac and PAP specimens. It seems likely, therefore, that reduction in number of pinnules is a real feature of this species rather than a loss of pinnules, damaged during the handling of the specimens

Interestingly, a species identified as Prionospio cf. ehlersi but lacking pouches was reported by Blake (1983) from the deep sea in the Antarctic and Chile. In a later publication Blake (1996) concluded that: “…these widely scattered deep-sea records of a P. ehlersi -like species that lack interparapodial pouches represent at least one, yet undescribed species.” It is likely that at least some of Blake’s specimens are P. amarsupiata sp. nov. In additional deep-sea material examined, Blake encountered a specimen that lacked pouches but had a full branchial set (first pair short and pinnate, pairs 2, 3, and 4 short, all the same length, thick, and apinnate). This particular specimen is clearly different from P. amarsupiata sp. nov. based on its branchial form.

Some specimens collected from HERMES canyons were reproductive with eggs, the largest of which were approximately 70 microns in diameter.

Etymology. amarsupiata , meaning “lacking pouches”; from the Latin marsupium, a pouch; reference is to the lack of interparapodial pouches in this species.

Distribution. This species is widespread in the deep sea; confirmed records indicate the species has been recorded from the Nazaré, Setúbal and Cascais canyons along the Portuguese margin (3199–4488 m), Crozet Island (3500 m), the Equatorial Pacific (EqPac), and the Northeast Atlantic ( Cape Verde Abyssal Plain 4500 m, Madeira Abyssal Plain 4800 m).

Figures

FIGURE 1. Maps showing location of collecting sites and distribution of species. a. Locations of the collection sites. CCFZ- Clarion—Clipperton Fracture Zone, W = west site, E = east site, A = UK concession area; CR—Crozet Island; CVAP Cap Verde Abyssal Plain; EP—Equatorial Pacific (EqPac); MAP—Madeira Abyssal Plain; PAP—Porcupine Abyssal Plain; PC— Portuguese Canyons. b. Distribution of Prionospio amarsupiata sp. nov (blue squares), Aurospio abranchiata sp. nov (orange triangles); c. Distrubutions of Prionospio branchilucida sp nov (purple stars), P. vallensis sp. nov (blue triangle); d. Distributions of Prionospio kaplani sp. nov (solid green hexagons); P. hermesia sp. nov (yellow circle), Aurospio tribranchiata sp. nov. (inverted orange triangle)

FIGURE 2. Profiles of anterior chaetigers of the Prionospio species described. 1) Prionospio amarsupiata sp. nov. a) Chaetiger 2; b) Chaetiger 3; c) Chaetiger 4; d) Chaetiger 5; e) Chaetiger 10; f) Chaetiger 22; scale bar = 100 Μm. 2) Prionospio vallensis sp. nov. a) Chaetiger 2; b) Chaetiger 3; c) Chaetiger 4; d) Chaetiger 5; scale bar = 200 µm. 3) Prionospio branchilucida sp. nov. a) Chaetiger 2; b) Chaetiger 3, the ventral lamellae can often be folded over forming a hollow and making the edge of the lamellae appear square in profile; c) Chaetiger 4; d) Chaetiger 5; e) Chaetiger 14; scale bar = 200 µm. 4) Prionospio hermesia sp. nov. a) Chaetiger 2; b) Chaetiger 3; c) Chaetiger 4; d) Chaetiger 5; e) Chaetiger 8; scale bar = 100 µm. 5) Prionospio kaplani sp. nov. specimen 735 a) Chaetiger 2; b) Chaetiger 3 showing both shapes of ventral lamellae; c) Chaetiger 4 also showing two basic morphologies of ventral lamellae; d) Chaetiger 5; e) Chaetiger 8 also showing alternative morphology of ventral lamellae; f) Chaetiger 14; scale bar = 200 µm. 6) Prionospio sp C a) Chaetiger 2; b) Chaetiger 3; c) Chaetiger 4; d) Chaetiger 12; e) Chaetiger 20; scale bar = 100 µm.

FIGURE 3. Prionospio amarsupiata sp. nov. a) Dorsal view of anterior chaetigers; scale bar = 200 µm. b) Lateral view of anterior chaetigers; scale bar = 500 µm; c) Photomicrograph of a group of neuropodial hooded hooks. d) Photomicrograph close-up of neuropodial hooded hooks; scale bar = 10 µm, applies to c) and d).