Politolana sanchezi, Frutos, Inmaculada & Sorbe, Jean Claude, 2010

Frutos, Inmaculada & Sorbe, Jean Claude, 2010, Politolana sanchezi sp. nov. (Crustacea: Isopoda: Cirolanidae), a new benthic bioturbating scavenger from bathyal soft-bottoms of the southern Bay of Biscay (northeastern Atlantic Ocean), Zootaxa 2640, pp. 20-34 : 22-28

publication ID	https://doi.org/ 10.5281/zenodo.198554
DOI	https://doi.org/10.5281/zenodo.6210534
persistent identifier	https://treatment.plazi.org/id/6877737C-5639-FFD9-5CC6-FA4A1A1EB8FE
treatment provided by	Plazi
scientific name	Politolana sanchezi
status	sp. nov.

Treatment

Politolana sanchezi View in CoL sp. nov.

( Figs 2–5 View FIGURE 2 View FIGURE 3 View FIGURE 4 View FIGURE 5 )

Material examined. Holotype: 1 male (TL = 14.6 mm), MNCN 20.04/8350, Le Danois Bank, 44º05.29’N, 04º40.48’W, RV Vizconde de Eza, ECOMARG 0 3, 17–18 October 2003, station TFS01, 545 m depth, fishbaited trap on photogrammetric sledge, fine sand bottom, temperature: 10.78ºC, salinity: 35.55.

Paratypes: 1 male (TL = 17.5 mm), MNCN 20.04/8351. 1 male (TL = 15.5 mm), MNCN 20.04/8352. 1 female (TL = 18.5 mm), MNCN 20.04/8353. Data as for holotype. 1 male (TL = 13.0 mm), MNHN-Is6286, ESSAIS I, 21 April 1989, station TS06-R-N3, 44°33.40’N, 02°10.70’W, 608–611 m; 1 female (TL = 15.0 mm), MNHN-Is6287, ESSAIS I, 21 April 1989, station TS07-R-N2, 44°31.90’N, 02°10.80’W, 660–714 m; Cap Ferret canyon, suprabenthic sledge.

Etymology. This species is named for Dr Francisco Sánchez (Instituto Español de Oceanografía, Santander), project manager and leader of the ECOMARG cruises.

Diagnosis. Body highly vaulted. Coxae 4–7 narrow with oblique impressions. Cephalon anterior margin slightly concave; lateral margins of raised frontal ridge extending over and dividing eyes. Eyes large, subrectangular, darkly pigmented. Interocular furrow complete. Antennae reaching middle of second pereonite. Pereopod 1 with meral lobe reaching midpoint of propodus; inferior margin of merus with row of acute robust setae. Merus and carpus of pereopod 4–6 without transverse rows of setae on posterior face; ischium superior margin without setae. P5–7 posterior distal margin of ischium without studded-biserrate setae. P7 superior distal angle of merus with long slender plumose setae. Uropod endopod apex narrowly subacute, with distomedial margin slightly concave; apex with cluster of long simple setae. Exopod shorter than endopod, with lateral margins slightly convex, apex with one robust seta and with a cluster of long simple setae. Pleotelson posterior margin broadly convex with small medial point, with plumose marginal setae and four small robust setae.

Description. Body length about 3.5 times width. Pereon cuticle highly polished; cream colour in alcohol with numerous dark chromatophores on cephalon, pereon, pleon and telson ( Fig. 2 View FIGURE 2 ).

Cephalon ( Fig. 2 View FIGURE 2 A, B) polished, not punctate. Lateral margins of raised frontal ridge extending over and dividing eyes. Interocular furrow complete. Eyes large, subrectangular, darkly pigmented; cuticular ommatidia facets slightly developed. Frontal lamina length about 4.8 times greatest width, reaching middle of antennule peduncles. Frontal lamina and clypeus ( Fig. 3 View FIGURE 3 A) with lateral margins raised as thickened ridges. Labrum ( Fig. 3 View FIGURE 3 A) posterior margin slightly concave.

Antennule ( Fig. 3 View FIGURE 3 B) peduncle articles with short simple and palmate setae on distal angles; peduncle article 3 1.1 times longer than wide, article 4 minute. Flagellum composed of 10 articles, each with 1–7 aesthetascs; first and second flagellar articles longest.

Antenna ( Fig. 3 View FIGURE 3 C) reaching middle of second pereonite. Peduncle articles 3–5 progressively longer, article 3 length subequal to greatest width, widening distally; article 4 longer than wide, posterior distal angle bearing 5 long simple setae and 2 short palmate seta; article 5 narrower than article 4, approximately 1.8 times longer than wide, posterior distal angle bearing few setae of different lengths and 2 short palmate setae. Flagellum composed of 18 articles, subquadrate proximally (except the first one), lengthening distally.

Mandible ( Fig. 3 View FIGURE 3 D) incisor process with 4 teeth on left mandible and 3 on right mandible (not figured). Spine row showing the same structure on right and left mandible, with 12 robust spines distally implanted on a cuticular fold (four of them, with wide base, parallel to incisor process; remaining ones, narrower at their base, perpendicularly arranged to the first ones). Anterior margin of molar process with numerous flat teeth, closely spaced, touching at their bases; submarginal setal row with 10 long setae; dorsal surface covered with fine setae arranged into small shingle-like rows. Palp article 2 with dense row of simple setae on distal half; article 3 with simple and slender setae.

Maxillule ( Fig. 3 View FIGURE 3 E) gnathal surface with 11 heavily sclerotized robust setae, several anterior ones with notched surface; lateral lobe with 6 minute setae along inner margin. Medial lobe with 3 large circumplumose setae and a smaller plumose seta between the two distal-most large setae.

Maxilla ( Fig. 3 View FIGURE 3 F) lobes with long simple and plumose setae.

Maxilliped ( Fig. 3 View FIGURE 3 G) endite with 3 distal robust circumplumose setae; right and left endites with 1 coupling hook. Outer and inner margins of palp with simple setae, inner margin of articles 4 and 5 also with serrate setae.

Pereon ( Fig. 2 View FIGURE 2 A, B) highly vaulted. Pereonite 5 longest; pereonite 2–3 shortest, subequal in length; pereonite 1 subequal in length to pereonite 7. In dorsal aspect, pereonite 1 narrows markedly to encompass cephalon; with distinct impression along lateral margin; anterolateral margins straight forming blunt anterior angles. Coxae 2 and 3 with impression parallel to lateral margin; coxae 4–7 posterior margins oblique with acute posterior angles, progressively more extended posteriorly, with distinct oblique impressions. Penes 3.4 times longer than wide, tapering distally (not figured).

Pleon ( Fig. 2 View FIGURE 2 A, B). Pereonite 7 slightly overlapping anterior dorsal portion of first pleonite. Epimera of pleonites 1–4 produced posteriorly, epimera 2–4 bearing dense lateral setal fringe. Ventral flanges hidden by epimera, with ventral posterior angles rounded.

Pereopods 1–3 ( Fig. 4 View FIGURE 4 A, B, C) basis with long simple setae on distal inferior angle, with a submarginal subdistal row of 5–7 simple setae and 4–5 stout circumplumose setae along superior margin. Ischium posterior face with 1 oblique row of simple setae. Merus superior distal angle produced into large recurved lobe reaching midpoint (P1) or only basal part of propodus (P2 and P3), with one (P1) or two (P2 and P3) apical setae; inferior margin of merus with row of acute robust setae. Ischial and meral lobes of P3 less produced than in P1 and P2. Inferior margin of propodus with row of 5 (P1), 4 (P2) and 3 (P3) acute robust setae. Dactyl length 0.6 propodus length; secondary ungui blunt and hardly visible.

Pereopods 4–6 ( Fig. 4 View FIGURE 4 D, E, F) ischium superior margin without setae on posterior face, with 3 submarginal setae along superior margin on anterior face; posterior distal margin with 2 slender simple setae (P4, P5) and only 1 in P6. Posterior face of merus and carpus without transverse rows of setae. Carpus 1.6–2.5 times longer than wide, widening distally (P5 and P6). Pereopod 6 superior distal angle of merus and carpus with long simple setae; propodus inferior margin with 3 clusters of setae (biserrate for the 2 distal ones), and with biserrate setae on inferior distal angle.

Pereopod 7 ( Fig. 4 View FIGURE 4 G) slightly shorter than P6; superior distal angle of merus with long slender plumose setae, long biserrate setae and short biserrate setae. Carpus distal margin expanded, about 3.3 times as wide as proximal propodal width; propodus length subequal to carpus length.

Pleopod 1 ( Fig. 5 View FIGURE 5 A) peduncle width 1.2 times length; with 6 plumose coupling hooks; endopod width less than half maximum width of exopod, plumose marginal setae on distal margin only; exopod with plumose marginal setae on distal and outer lateral margins. Pleopod 2 ( Fig. 5 View FIGURE 5 B) peduncle wider than long with 5 plumose coupling hooks and 2 distal plumose setae. Appendix masculina narrow, of relatively constant width, tapering evenly to rounded apex, extending well beyond distal margin of endopod and exopod. Pleopod 3–4 with 3 plumose coupling hooks and 2 distal plumose setae; endopod width more than half width of exopod, plumose marginal setae on distal margin; exopod with plumose marginal setae on distal and outer lateral margins (not figured). Pleopod 5 ( Fig. 5 View FIGURE 5 C) endopod with large proximomedial lobe, without plumose setae; exopod large, with plumose marginal setae on distal and outer lateral margins.

Uropod ( Fig. 5 View FIGURE 5 D) peduncle with outer setal fringe extending onto distal margin; medial process distally acute, with 5 long plumose setae along distal inner margin. Endopod apex subacute, with distomedial margin slightly concave; apex with cluster of 4 long simple setae, flanked by a short robust setae; distomedial margin with 4 additional small robust setae and plumose marginal setae; outer distal margin with deep notch, housing a short circumplumose seta and a short robust seta; plumose marginal setae on lateral and distal margins except in notch; with a proximal row of 3 palmate setae and a distal cluster of two plumose setae (near notch) on dorsal surface. Exopod shorter than endopod, with lateral margins slightly convex, apex with a robust seta and with a cluster of long simple setae; distal outer margin with a small robust seta.

Pleotelson ( Fig. 2 View FIGURE 2 C) broadly convex with small medial point, with numerous plumose setae, four small robust sensory setae and one small non plumose median seta (half length of adjacent plumose ones) on distal margin.

Variation. All the males examined show the main morphological features presented in the subsequent identification key and most of the variation observed is likely due to size and age differences. The smallest male (manca stage 3; TL: 9.1 mm) is characterized by the absence of body chromatophores, antennular and antennal flagella with fewer articles than holotype (7 and 15 articles, respectively) and appendix masculina not reaching beyond distal margin of endopod.

Sexual dimorphism. Males and females of Politolana sanchezi sp. nov. show similar morphology, both with numerous dark chromatophores on cephalon, pereon, pleon and pleotelson. The total body length of individuals examined varies from 5.1 to 7.8 mm in mancas 1–2 (not sexually differentiated), from 9.1 (manca 3) to 17.5 mm in males, and from 14 to 19 mm in females (adult individuals). When compared to the male holotype, the female paratype (MNCN 20.04/8353) shows a few distinct features: higher body length/width ratio (4.1 times), right endite of maxilliped with 2 coupling hooks (only 1 on the corresponding left endite), pleotelson apex more pointed. The smallest individuals (mancas) were sampled on April 2004 (TS03-A, suprabenthic sledge) and the biggest ones (adult females) on October 2003 (TSF01, fish-baited trap). One brooding female (16 mm TL, sample FLU01b) contained in its marsupium 29 individuals (length: 2.06 mm; width: 0.95 mm) with pigmented eyes and developing appendages.

Remarks. Politolana sanchezi sp. nov. can best be identified by the following combination of characters: superior lobe of P1 merus reaching beyong the midpoint of propodus and equalling half the merus length; pleonite 1 not completely overlapped by pereonite 7; pleotelson posterior margin broaded convex with small medial point. It is easily differentiated from P. microphthalma (the only species previously known from European waters; see Costello et al. 2008) by its antenna reaching middle of second pereonite, lateral margin of frontal ridge dividing eyes, larger eyes, P1 superior meral lobe reaching beyond midpoint of propodus, outer distal margin of uropodal endopod deeply notched and pleotelson apex broadly convex with small medial point. On the other hand, P. sanchezi sp. nov. is very similar to P. haneyi Riseman and Brusca 2002 from the northeastern Pacific (Guaymas Basin, Gulf of California). Apart from its distinct geographical distribution, it can be distinguished by the close disposition of teeth on the anterior margin of its mandible molar process, the apex of the uropodal endopod with 1 robust seta and the distal margin of pleotelson broadly convex with small medial point.