Paranthura santiparrai Frutos, Sorbe & Junoy, 2011, sp. nov.

Paranthura santiparrai sp. nov.

(Figs 2–10)

Material examined. Holotype: 1 brooding female, 6.6 mm total body length, MNCN 20.04/8224, NE Atlantic Ocean, 'El Cachucho' MPA, RV Vizconde de Eza, ECOMARG 0 3 cruise, 17 October 2003, Arcachon suprabenthic sled, station E03-TS3b, 44º05.85’N, 4º51.08’W, 574 m depth, 0–50 cm near-bottom water layer; dissected, three slides and one vial.

Allotype: 1 male, MNCN 20.04/8225, data as for holotype; dissected, two slides and one vial.

Paratypes: 1 female, MNCN 20.04/8368, data as for holotype, prepared for SEM. 1 female, MNCN 20.04/ 8369, data as for holotype, prepared for SEM. 3 males and 3 females, MNCN 20.04/8370, data as for holotype, one vial. 1 immature male, MNCN 20.04/8438, data as for holotype, one slide and one vial. 1 manca stage, MNCN 20.04/8459, data as for holotype, one vial.

Etymology. The species is named after Dr Santiago Parra, benthologist at the Instituto Español de Oceanografía, La Coruña, Spain.

Description. Holotype, adult female with oostegites (Figs 2–5).

Total body length 6.6 mm, about 13.3 times longer than greatest width; colour pale yellow in alcohol, pigmentless. Body proportions: C<1<2>3<4≈5>6>7<Pln<Plt. Cephalothorax 1.5 times longer than wide, without eyes. Pleon shorter than pleotelson, anterior part narrower than pereonite 7 width; pleonites 1–5 free, equal in length; pleonite 6 dorsally with medial incision on distal margin (Fig. 2 A).

Antenna 1 (Fig. 3 A) peduncle 2 times longer than flagellum; article 1 almost as long as articles 2 and 3 together, article 2 shortest. Flagellum of 4 articles, shorter than two last articles of peduncle; article 1 short, article 2 longest, articles 3 and 4 minute.

Antenna 2 (Fig. 3 B) peduncle having article 2 most robust, article 5 slightly shorter than articles 3 and 4 together; flagellum of 4 articles, last three minute, distal one hidden by long apical setae emerging from third one.

Mandible (Fig. 3 C) incisor acute, longer than palp. Palp of 3 articles: article 1 shorter than article 3; article 2 with a sub-distal seta; article 3 distally with a comb-like longitudinal row of 10 thick setae increasing in length towards the apex.

Maxilla (Fig. 3 D) in form of a finely toothed stylet, with 10 teeth.

Maxilliped (Fig. 3 E) palp of 2 articles, apical one minute; article 1 medially with one proximal seta and 3 distal ones, and laterally with 1 seta; article 2 with 2 apical setae.

Pereopods (Fig. 4). P1 most robust, subchelate, basis 2.0 longer than wide, carpus triangular with a distal group of simple setae; propodus enlarged, 1.3 times longer than wide, posterior margin bordered by simple setae, proximally ended by a small lobe, dactylus closing across mesial propodus face, palm convex with a continuous row of 14 setae, dactylar unguis reaching propodal lobe (Fig. 4 A). P2 and P3 similar; P2 basis 3.0 times longer than wide, carpus triangular, propodus oval, 1.6 times longer than wide, with setae and 9 stout sensory setae on slightly convex palm (Fig. 4 B); P3 basis 3.6 times longer than wide, carpus triangular, propodus oval, 1.7 times longer than wide, palm slightly convex with submarginal row of setae and 9 stout sensory setae (Fig. 4 C). P4 and P5 similar: basis 3.3 and 3.9 times longer than wide (respectively), ischium as wide as basis, merus with 2 anterodistal and 2 posterodistal simple setae, carpus rectangular 2.6 and 2.9 times longer than wide (respectively), with long setae as well as 4 and 3 stout sensory setae on posterior margin (respectively); propodus rectangular 3.7 and 4.5 longer than wide (respectively), with scales and 4 stout sensory setae on posterior margin (Fig. 4 D, E). P6 and P7 similar; P6 basis 3.6 times longer than wide, ischium as wide as basis, merus with 2 anterodistal and 2 posterodistal simple setae; carpus rectangular 3.4 times longer than wide, with long setae and 3 stout sensory setae on posterior margin; propodus rectangular 4.7 times longer than wide, with 4 stout sensory setae on posterior margin (Fig. 4 F); P7 the longest, basis 3.5 times longer than wide, ischium as wide as basis, merus with 1 anterodistal and 2 posterodistal simple setae; carpus rectangular 3.7 times longer than wide, with scales and 3 stout sensory setae on posterior margin; propodus rectangular 4.5 longer than wide, with scales and 4 stout sensory setae on posterior margin (Fig. 4 G).

Pleopods (Fig. 5 A, B). Pl1 sympod with 3 distal serrulate setae on mesial margin; exopod operculiform, 2.0 times longer than wide, distally surrounded by 18 plumose setae, with some short simple setae on dorsal surface; endopod narrow, 7.7 times longer than wide, slightly reaching beyond apex of exopod, distally with 8 plumose setae. Pl2 sympod with 3 distal serrulate setae on mesial margin; exopod 3.0 times longer than wide, distally surrounded by 10 plumose setae; endopod 3.5 times longer than wide, not reaching apex of exopod, with 4 distal plumose setae.

Telson (Fig. 5 C) without statocyst, posterior margin evenly rounded, 2.3 times longer than greatest width.

Uropod (Fig. 5 D) sympod elongate, rectangular, 2.1 times longer than wide, as long as exopod, with 1 plumose seta at mesiodistal angle and 1 simple seta at outer distal angle. Endopod ovate, 1.5 times longer than wide, reaching apex of telson, surrounded laterally and distally by 27 long simple setae and a few smaller ones. Exopod ovalshaped with rounded tip, 2.1 times longer than wide; left and right exopods folded over pleotelson, proximally not meeting each other in dorsal view.

Allotype, adult male (Figs 2, 6–9).

Total body length 5.4 mm, about 13.9 times longer than greatest width; without eyes; colour pale yellow in alcohol, pigmentless. Body proportions C<1<2>3<4>5>6>7<Pln<Plt, Prn 4 longest (Fig. 2 B).

Antenna 1 (Fig. 6 A) peduncle of 3 articles, first one longest. Flagellum of 8 articles; article 1 short, about one quarter of article 2 length; article 2 longest; articles 3, 4 and 5 equal in length, about half of article 2 length; articles 6 and 7 equal in length, about 0.8 of article 2 length, article 8 smallest; articles 2–8, each with long setae and long aesthetascs disposed in transverse circles along distal margin.

Antenna 2 (Fig. 6 B) like in female.

Mandible (Fig. 6 C) like in female. Palp: article 1 with a distal seta; article 3 distally with a comb-like longitudinal row of 8 thick setae, proximal one shortest.

Maxilla (Fig. 6 D) like in female, but with only 9 teeth.

Maxilliped (Fig. 6 E) like in female. Palp: article 1 mesially with one proximal seta and 4 distal ones, and laterally with 1 seta.

Pereopods (Fig. 7). P1 most robust, subchelate, propodus enlarged, 1.6 times longer than wide, with a continuous row of 19 setae on mesial face, dactylus unguis reaching proximal propodal lobe (Fig. 7 A). P2 and P3 similar; P2 propodus oval, 2.0 times longer than wide, with setae and 9 stout sensory setae on convex palm (Fig. 7 B); P3 propodus oval, 2.1 times longer than wide, with setae and 7 stout sensory setae on convex palm (Fig. 7 C). P4 and P5 similar: carpus 2.8 and 3.2 times longer than wide (respectively), with long setae and 3 stout sensory setae on posterior margin; propodus rectangular 3.5 and 5.0 longer than wide (respectively), with scales and 3 stout sensory setae on posterior margin of P4, and 4 ones on P5 (Fig. 7 D, E). P6 and P7 similar; P6 carpus rectangular, 3.7 times longer than wide, with long setae and 3 stout sensory setae on posterior margin; propodus rectangular, 4.5 longer than wide, with 4 stout sensory setae on posterior margin (Fig. 7 F). P7 longest: basis 3.9 times longer than wide, ischium as wide as basis, merus with 1 anterodistal and 2 posterodistal simple setae; carpus 4.1 times longer than wide, with scales and 3 stout sensory setae on posterior margin; propodus rectangular, 4.6 longer than wide, with scales and 3 stout sensory setae on posterior margin (Fig. 7 G).

Pleopods (Fig. 8 A, B). Pl1 sympod with 3 distal serrulate setae on mesial margin; exopod operculiform, distally surrounded by 13 plumose setae, with some short simple setae on dorsal surface; endopod narrow, reaching apex of exopod, distally with 10 plumose setae. Pl2 sympod with 2 distal serrulate setae on mesial margin; exopod with 8 distal plumose setae; endopod reaching apex of exopod, with 4 distal plumose setae; appendix masculina stylet-like, articulating in proximal fourth part of endopod mesial margin, 1.1 times longer than endopod, reaching well beyond endopod, apically hooked.

Uropod (Fig. 9 A) sympod elongate, rectangular; endopod ovate, surrounded laterally and distally by about 22 simple long setae, slightly reaching beyond apex of telson; exopod oval-shaped with rounded tip, slightly shorter than sympod, with about 20 plumose and simple setae on mesial margin; left and right exopods folded over pleotelson, proximally not meeting each other in dorsal view.

Telson (Fig. 9 B) without statocyst, 2.0 times longer than greatest width, oval, tapering in rounded apex with 8 apical setae, dorsally with 9 pairs of fine setae.

Paratype, manca (Fig. 2 C, D)

Total body length 2.52 mm, without eyes, P7 absent, sex undifferenciated.

Paratype, immature male (Fig. 8 C)

Total body length 4.23 mm, without eyes. A1 without aesthetascs. Pl2 exopod with 7 distal plumose setae; endopod not reaching apex of exopod, with 3 distal plumose setae; appendix masculina reaching well beyond endopod and not yet fully separated from it, enclosed in a cuticular bag giving a wider appearance than in adult male, apically hooked.

Paratype, females

SEM observations carried out on two paratype females (MNCN 20.04/8368 and MNCN 20.04/8369) confirm the absence of ocular structure on the cuticular surface of the head (pictures not shown).

Distribution. The known distributional area of the new Paranthura species is at the moment limited to the 'El Cachucho' MPA (S Bay of Biscay).

Remarks. The family Paranthuridae (sensu Poore 2001) comprises six genera that share two synapomorphies: lack of statocyst and maxillipedal palp with fused articles, except sometimes for minute distal one. The specimens from the 'El Cachucho' MPA show these two characters (Fig. 10) and belong to the family Paranthuridae. They are blind and pigmentless, as also mentioned for the two paranthurid genera Pseudanthura and Cruregens. However, they can be attributed to none of these two genera. In the first one, all pleonites and pleotelson are fused in a single posterior unit (pleonites 1–5 free in the 'El Cachucho' specimens). In the second one (a monotypic genus represented by a hypogean freshwater species from New Zealand), P7 are absent in adults (present in adults of the 'El Cachucho' specimens). Furthermore, in both genera, the posterior margin of Pln 6 is not visible dorsally (dorsally well delineated from telson in the 'El Cachucho' specimens). The four remaining paranthurid genera generally show a pigmented body and more or less developed eyes (scattered ommatidia in some species). According to Poore (2001), the genus Paranthura can be distinguished from the three other ones (Califanthura, Colanthura and Cruranthura) by the following characters: mandibular incisor acute (vs. blunt), mandibular molar absent (vs. curved flange-like molar), mandibular palp present (vs. absent), maxillipedal palp almost as long as basis (vs. half as long as basis), row of setae evenly spaced along palm on mesial face of P1 propodus (vs. row of closely-set setae confined proximally), P7 present in adults (vs. absent). All these 6 discriminating characters are actually observed in the 'El Cachucho' specimens and they are therefore assigned to genus Paranthura. However, such an assignment is not full accordance with the successive diagnoses given for this genus (Barnard 1925; Miller & Menzies 1952; Poore 1980, 1984, 2001; Kensley & Schotte 1989, 2000), all of them mentioning the presence of developed eyes.

Consequently, we propose an emendation of the most recent diagnoses of genus Paranthura given by Kensley and Schotte 2000 and Poore 2001.

Whereas some deep-sea anthuroids are blind (see Kensley 1982), all the known Paranthura species living at more than 200 m depth have well developed eyes (P. antarctica Kussakin, 1967, 3– 334 m; P. argentinae Kussakin, 1967, 399– 508 m; P. ciliata Whitelegge, 1901, 98– 329 m; P. c o s t a n a Bate & Westwood, 1868, 0–355 m; P. longa Wägele, 1985, 514 m; P. neglecta Beddard, 1886, 131– 283 m; P. possessia Kensley, 1980, 508– 2707 m; data from Poore 2001). The bathyal P. santiparrai sp. nov. can be easily distinguished from the other European Paranthura (the natives P. costana and P. nigropunctata as well as the non-indigenous P. japonica) by the lack of eyes and body pigmentation. Some other discriminating morphological features can also be used (see key and Table 2). On the basis of these data (known depth range of species, structure of appendix masculina apex), the new species is closer to P. costana than to P. nigropunctata (both species are mentioned from northern Spain, see Junoy & Castelló 2003), suggesting that it could have evolved from this shallower eyed species in relation with the seamount-like feature of the Le Danois Bank, a deep plateau more or less isolated from the adjacent Cantabrian shelf (isolation mechanism of speciation).

As frequently mentioned for many other anthuroid taxa (e.g. Kensley 1978, Negoescu 1999), the pleopodal sympods of the new Paranthura species bear a few distal setae on their mesial margins. Careful observations of right and left paired pleopods reveal that these setae are actually in close contact in the sagittal plane but not morphologically structured to cling to each other (see Figs 5 A, B; 8A, B). Therefore, they cannot be designated as retinacles according to the definition given by Negoescu (1994; retinacula: coupling hook on pleopod sympod, simple or with outgrowths). According to the setal classification system proposed by Garm (2004; pers. comm.), these distal setae show small setules only located on the distal part of their shaft and therefore belong to the serrulate setal type.

As yet pointed out by Negoescu (2000), many descriptions of new anthuroid species are incomplete and frequently based on adult specimens exclusively. Fortunately, in the case of genus Paranthura, three species were described in a highly detailed manner, including all successive developmental stages encountered in their respective populations: P. nigropunctata and P. c o s t a n a by Wägele (1982; European species) and P. brucei by Negoescu (1999; from Fiji islands). In both P. c o s t a n a and P. brucei, the figured appendix masculina of young males was apparently not enclosed in a cuticular bag, a peculiar morphological feature well observed in the case of immature P. santiparrai sp. nov. Apparently never mentioned in anthuroid literature, such an original feature of immature males probably represents a premolt condition before maturity stage characterized by a free functional appendix masculina.