Pholoides sinepapillatus, Miranda & Brasil, 2014

Miranda, Vinícius Da Rocha & Brasil, Ana Claudia Dos Santos, 2014, Two new species and a new record of Scale-worms (Polychaeta) from Southwest Atlantic deep-sea coral mounds, Zootaxa 3856 (2), pp. 211-226 : 213-215

Pholoides sinepapillatus sp. nov.

Figures: 2 A–E; 3 A–K

Material Examined: 4 spms.; HOLOTYPE: 2 spms., IBUFRJ-2131 , ECOPROF 9, 639 m, 40º5'45,06"W – 22º22'41,48"S, 22/12/2008, on Solenosmilia variabilis . PARATYPES: 2 spms., IBUFRJ-2130, ECOPROF 10, 622 m, 40º5'39,24"W – 22º22'3,21"S, 17/01/2009, on Errina sp.

Diagnosis: Prostomium globular, with two pair of eyes. Lips of the mouth, the surface of the elytra and the ventral surface of the body smooth. Biramous parapodia with noto- and neuropodium of the same size. Elytra with faint concentric rings easily observed by transparency.

Description: Holotype with 36 segments (length: 5.07 mm; width 0.7 mm); paratypes with number of chaetigers varying from 27 (length: 2.6 mm; width: 0.6 mm) up to 35 (length: 4.62 mm; width 0.7 mm).

Body dorsoventrally flattened, dorsal and ventral surfaces without papillae or tubercles ( Fig. 2A ). Prostomium and tentacular segment fused ( Fig. 3A ). Prostomium globular, as wide as long, one pair of eyes; antenna with ceratophore at anterior margin of prostomium, style papillate and inflated subdistally, 1.5 times longer than prostomium. First segment anterior and lateral to prostomium ( Fig. 3B ), parapodia uniramous with notoacicula not extending beyond epidermis and without papillae on the ventral side; each parapodia with bundle of long, serrate capillary chaetae ( Fig. 3C–D ); dorsal cirrus ( Fig. 3E ) length similar to median antenna, and a stout ventral palp.

Elytra on bulbous elytrophores on segments 2, 4, 5, 7, continuing on alternate segments to end of body; last two segments without elytra or dorsal tubercles. Elytra large, thick, subtriangular ( Fig. 3F ) to reniform ( Fig. 3G ), papillae on margins not covered by adjacent elytra; smooth surfaces and faint concentric rings visible ( Figs. 2B ). Segments without elytra with small dorsal tubercles ( Fig. 3A ).

Second segment with biramous parapodia ( Fig. 3H ), one acicula per ramus, not extending beyond epidermis; ventral cirri with short, papillate cirrostyles. Notochaetae ( Figs. 2C ; 3C–D ) capilliform, curved and serrate. Neurochaetae compound ( Figs. 2D–E ; 3I–J ), supracicular shorter than subacicular; shafts and blades of supracicular neurochaetae smooth; shafts of subacicular neurochaetae subdistally spinose, blades serrate and longer than blades of supracicular neurochaetae.

Remaining parapodia biramous ( Fig. 3K ); notopodia as long as neuropodia, distally rounded to subconical, with serrate capilliform notochaetae ( Figs. 2C ; 3C–D ) and notoaciculae slightly extending beyond epidermis. Neuropodia with compound neurochaetae of two kinds: supracicular smaller than subacicular, shafts and blades of supracicular smooth; shafts of subacicular subdistally spinose, blades serrate and longer than supracicular ( Figs. 2D–E ; 3I–J ); neuroaciculae not extending beyond epidermis, each neuroacicular lobe with small digitiform process near distal end of acicula. Ventral cirri present, with few short papillae on cirrostyles ( Fig. 3K ).

Etymology: The name of the species refers to the fact that it doesn´t have papillae over the dorsal and ventral surfaces of the body, neither over the surface of the elytra, as observed in the other species of the genera.

Habitats: Associated with Solenosmilia variabilis and Dendrophiliidae corals, in a depth range from 600m to 640m.

Remarks: P. sinepapillatus sp. nov. differs from the other two recognized species of Pholoides by having smooth ventral and dorsal surfaces: papillae are present on the ventral surface of the body of the two other Pholoides species ( P. dorsipapillatus ( Marenzeller, 1893) and P. asperus ( Johnson, 1897)) . The surface of the buccal lips differs among the three species. While P. dorsipapillatus has papillae over the ventral lip and P. asperus both lips papillated, P. sinepapillatus sp. nov. has both lips smooth. Additionally specimen of P. sinepapillatus sp. nov. did not show papillae on the dorsal tubercle, as is observed in the other two species of Pholoides . As in P. dorsipapillatus , P. sinepapillatus sp. nov. did not show papilla on the ventral side of the first segment, while this papilla is present in P. asperus .

In both species already described, the elytra show papillae on the dorsal surface, while P. sinepapillatus sp.nov. has smooth dorsal and ventral surface of elytra. Pettibone (1992) already emphasized the presence of knobbed papillae near the margins and middle region of elytra in P. asperus . While P. asperus presents strongly marked concentric rings, P. sinepapillatus sp. nov. and P. dorsipapillatus , show faintly marked concentric rings.

According to the description provided by Pettibone (1992) for P. dorsipapillatus , P. sinepapillatus sp.nov. is not significantly different regarding the parapodium and the compound chaetae. Both species present noto- and neuropodium almost with the same size; upper neurochaetae with blades longer than lower neurochaetae, presenting faintly spinose or smooth, and the shafts can be smooth or subdistally spinose. But when compared with P. asperus some differences can be noticed such as the notopodium in P. asperus , that is smaller than the neuropodium and presents a pair of papillae in the presetal lobe and postsetal lobe covered with papillae; the neurochaetae of P. asperus differ from P. sinepapillatus sp.nov. by having larger and serrated blades and a longer spinose shaft.

Another outstanding distinctive character is the number of eyes, while P. dorsipapillatus and P. asperus show two pairs of eyes, P. sinepapillatus sp.nov. has only one pair of eyes situated on the widest part of the prostomium. Pholoides mendeleevi ( Averincev 1978) was illustrated with one pair of eyes (Fig. 8: 76– 80 p. 69), so this would not be the first register of Pholoides presenting this character, which is not mentioned by Pettibone (1992) in her revision of the genus. We believe that the presence of at least one pair of eyes could be used as a basic characteristic of the genus Pholoides .

Pholoides sinepapillatus sp.nov. is not the first species of Pholoides recorded for Brazilian waters. Sumida et. al (2004) reported P. asperus occurring in seabed pockmarks at Santos Basin, off the coast of São Paulo (26ºS; 46ºW) at a depth of almost 700m. Pinto (2014) also reported another species of Pholoides for Brazil, however the species described by her possess oval prostomium, first segment with prominent ventral papilla, body surface presenting papillae, elytra with faint concentric rings and notopodia smaller than neuropodia; instead of the global prostomium, first segment without ventral papilla, elytra with strongly marked concentric rings and noto- and neuropodia with the same size, as observed in Pholoides sinepapillatus sp.nov. described herein.

Distribution: Southwest Atlantic, currently known only from the type locality, Campos Basin, State of Rio de Janeiro, Brazil.

Figures

FIGURE 2. Pholoides sinepapillatus sp. nov. (A) View of the Holotype in a hole on dead Solenosmilia variabilis; (B) SEM of the dorsal surface of middle right elytra; (C) Detail of the tip of a notochaeta from a middle parapodium; (D) Blade and distal shaft of upper neurochaeta; (E) Blade and distal shaft of lower neurochaeta. (Scales bars: A=1 mm; B=200 µm; C, D, E= 10 µm).

FIGURE 3. Pholoides sinepapillatus sp. nov. (Holotype, IBUFRJ-3121) (A) Dorsal view of the anterior end; (B) Tentaculophore from right side (without dorsal cirrus); (C) Notochaeta; (D): Tip of same; (E) Style of dorsal cirrus of tentaculophore; (F) First elytra, right side; (G) Middle elytra, right side; (H) Parapodium from second segment; (I) Lower compound neurochaeta; (J): Upper compound neurochaeta; (K) Left middle elytrigerous parapodium. (Scales bars: A= 500 µm; B= 250 µm C= 50 µm, D, I and J= 150 µm and E= 75 µm; F, G, H and K = 300 µm).