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 : 28-29

Key to the world species of Politolana Bruce 1981

(modified from Riseman & Brusca 2002; completed from data in Riseman et al. 2001)

This key considers exclusively species that belong to Politolana sensu stricto (see Riseman & Brusca 2002), characterized by the frontal lamina being narrow and blade-like (length about 4–5 times width) or highly reduced. In the case of P. sanchezi sp. nov., this key can be used for adult males and females as well as for mancas down to a minimum TL of 5.1 mm. Figure 6 shows the geographical distribution of all known species in this genus, most of them from North America.

1 Pereopod 1 with superior distal angle of merus produced into a small lobe just reaching the base of the propodus and equalling only one-quarter the length of the merus; coxae 4–6 without oblique impressions; cuticular ridge of cephalon frontal margin laterally reaching, but not dividing eyes ......................................................................................... 2

- Pereopod 1 with superior distal angle of merus produced into a large recurved lobe reaching beyond the midpoint of the propodus and equalling half the length of the merus; coxae 4–6 with distinct or weak oblique impressions; cuticular ridge of cephalon frontal margin laterally reaching and dividing eyes ............................................................... 5

2 Frontal lamina greatly reduced to a small ridge sitting deep between the antennae; ventral margin of eyes with fringe of simple setae; setation of antenna 2 peduncle dense, article 5 with cluster of about 15 stiff simple setae ................. ............................................................................................................................................... P. polita (Stimpson 1853) northwestern Atlantic (from Bay of Fundy to about 38°N), 0–86 m

- Frontal lamina narrow, length about 4–5 times width, ventral margin of eyes without fringe of simple setae; antenna 2 peduncle article 5 with cluster of about 6 or fewer stiff simple setae....................................................................... 3

3 Pleotelson posterior margin convex (juveniles) or emarginate (adults); uropod exopod length subequal to endopod length, narrow and rounded in cross section ................................................................ P. concharum (Stimpson 1853) northwestern Atlantic (from Nova Scotia to about 22°N), 0–317 m

- Pleotelson posterior margin evenly convex or narrowly truncate; uropod exopod length shorter than endopod length, flattened with convex lateral margins ........................................................................................................................... 4

4 Antennae 2 reaching middle of pereonite 2; pleon epimere flanges with ventral posterior angle produced into a fine point; pleotelson posterior margin evenly convex; pereopod 4 propodus with sparse setae on superior margin .......... .............................................................................................................................. P. impostor Riseman & Brusca 2002

northwestern Atlantic (from Nova Scotia to about 38°N), 29–587 m - Antennae 2 laterally reaching anterior region of pereonite 1; pleon epimere flanges with ventral posterior angle blunt or rounded; pleotelson posterior margin narrowly truncate; pereopod 4 propodus without setae on superior margin. ..................................................................................................................................... P. microphthalma* ( Hoek 1882) northeastern Atlantic (from Barents Sea to northern North Sea), 82–440 m

5 Pereon-pleon articulation tight, with pleonite 1 visible, not completely overlapped by pereonite 7; pleon convex like pereon such that ventral flanges are hidden by epimera; uropod endopod apex subacute, with distomedial margin slightly concave, apex with cluster of long simple setae ............................................................................................. 6

- Pereon-pleon articulation loose, with pereonite 7 overhanging and overlapping pleonite 1 and sometimes pleonite 2; pleon more dorsoventrally compressed than pereon such that epimeres are laterally flared and do not hide the ventral flanges; uropod endopod apex broadly rounded or truncate, apex with or without cluster of long simple setae ........ 7

6 Body without chromatophores; molar process anterior margin with teeth widely spaced, not touching at their base; apex of uropod endopod with 2 short robust setae; pleotelson posterior margin evenly and narrowly rounded .......... ................................................................................................................................ P. haneyi Riseman & Brusca 2002 Gulf of California, Gulf of Mexico and Florida, 92–311 m

- Body with chromatophores on the cephalon, pereon, pleon and telson; molar process anterior margin with teeth closely spaced, touching at their base; apex of uropod endopod with 1 robust seta; pleotelson broadly convex with small median point.......................................................................................................................... P. sanchezi sp. nov. southern Bay of Biscay and west Galicia, 480–829 m

7 Uropod exopod long, reaching beyond endopod and pleotelson, lateral margins relatively straight, tapering evenly; pereonite 1 anterolateral margin sinuate, forming acute anterior point; pleotelson posterior margin medially produced into acute point; pereopods 5–7 posterior distal margin of ischium with simple acute robust setae; pleopod 1 peduncle width nearly twice length; pleopod 1 endopod width greater than half the width of exopod ........................ ................................................................................................................................................ P. eximia (Hansen 1890) off Brazilian coast**, 50–380 m

- Uropod exopod shorter than or subequal to endopod, with lateral margins slightly convex; pereonite 1 anterolateral margin straight, forming rounded or blunt anterior angle; pereopods 5–7 posterior distal margin of ischium with studded-biserrate setae; pleopod 1 peduncle subquadrate, or with length only slightly less than width; pleopod 1 endopod width about one half width of exopod .......................................................................................................... 8

8 Cephalon with additional transverse cuticular ridge present between frontal ridge and the interocular furrow; pereopod 7 coxa with distinct oblique impressions; antenna 2 not reaching pereonite 2; frontal lamina narrow, usually spatulate (anteriorly widened); pleotelson posterior margin with plumose marginal setae and four small robust setae; pereopods 4–7 posterior distal margin of ischium with studded-biserrate setae ............................................................ ................................................................................................................ P. tricarinata Riseman, Pires & Brusca 2001 off Brazilian coast**, 15–48 m

- Cephalon without transverse cuticular ridge between frontal ridge and the interocular furrow; pereopod 7 coxa with or without residual oblique impressions, never complete and distinct; antenna 2 reaching pereonite 2; frontal lamina narrow with slight hourglass shape or evenly wide; pleotelson posterior margin with plumose marginal setae, with or without minute robust setae; studded-biserrate setae absent on posterior distal margin of pereopod 4 ischium, present on ischium of pereopods 5–7 ...................................................................................................................................... 9

9 Eyes present, darkly pigmented ........................................................................................... P. impressa (Harger 1883) northwestern Atlantic (from Massachusetts to Florida), NE Gulf of Mexico, 73–700 m

- Eyes wanting or greatly reduced ......................................................... P. wickstenae Wetzer, Delaney & Brusca 1987 N Gulf of Mexico, 488–600 m

Figures

FIGURE 6. Geographical distribution of Politolana species, based on data from Wetzer et al. 1986, Riseman et al. 2001, 2002. Each species symbol on the planisphere is located at the sampling station of the corresponding holotype, except for P. eximia (original station not known; symbol positioned centrally on the Brazilian coast).