Sternaspis buzhinskaja

Salazar-Vallejo, Sergio I., 2014, Three new polar species of Sternaspis Otto, 1821 (Polychaeta: Sternaspidae), Zootaxa 3861 (4), pp. 333-344 : 342

Key to species of Sternaspis Otto, 1821

(Modified after Salazar-Vallejo & Buzhinskaja 2013 )

1 Ventro-caudal shield fan with a distinct median notch........................................................ 2

- Ventro-caudal shield fan continuous, without distinct median notch............................................. 12

2(1) Shield with radial ribs and concentric lines distinct........................................................... 3

- Shield with radial ribs distinct, concentric lines barely visible................................................. 10

3(2) Fan with median notch shallow.......................................................................... 4

– Fan with median notch deep; shields usually with concentric bands.............................................. 5

4(3) Shield with distinct concentric bands; main rib and posterior corners directed posteriorly.............................................................................................. S. affinis Stimpson, 1864 (NE Pacific Ocean).

- Shield without concentric bands; posterior corners directed laterally......................................................................................... S. scutata ( Ranzani, 1817) (Mediterranean Sea and NE Atlantic Ocean).

5(3) Shield with posterior corners distinct in frontal view......................................................... 6

- Shield with posterior corners poorly defined in frontal view.................................................... 7

6(5) Radial ribs and concentric lines distinct, well defined; body whitish to grayish............................................................................................... S. costata von Marenzeller, 1879 (NW Pacific Ocean).

- Radial ribs and concentric lines barely defined; body brownish...................... S. sendalli n. sp. ( Antarctic Ocean)

7(5) Anterior keels usually exposed.......................................................................... 8

- Anterior keels rarely exposed; fan barely projecting posteriorly beyond posterolateral corners......................... 9

8(7) Shield with anterior corners projecting at least as far as anterior keels, longer in larger specimens; fan margin crenulated in small specimens, dentate in larger ones....................................... S. buzhinskajae n. sp. (Arctic Ocean)

- Shield with anterior corners projecting as far as anterior keels; fan margin smooth to crenulated, never dentate................................................................. S. islandica Malmgren, 1867 (NE Atlantic Ocean, Iceland)

9(7) Introvert and body with similar pigmentation or introvert paler; shield widest medially.............................................................................................. S. fossor Stimpson, 1853 (NW Atlantic Ocean)

- Introvert and body with different pigmentation, introvert darker; shield widest anteriorly........................................................................ S. annenkovae Salazar-Vallejo & Buzhinskaja, 2013 (NW Pacific Ocean)

10(2) Main ribs markedly divergent; fan as wide as anterior margins or wider............................................................................................ S. maior Chamberlin, 1919 (Eastern Pacific, Gulf of California).

- Main ribs moderately divergent; fan half as wide as anterior margins........................................... 11

11(10) Posterior margin truncate, with lateral notches; ribs well-developed........................................................................................ S. maureri Salazar-Vallejo & Buzhinskaja, 2013 (Central Eastern Pacific)

- Posterior margin with a median notch, lateral notches shallow or indistinct; ribs poorly developed............................................................... S. williamsae Salazar-Vallejo & Buzhinskaja, 2013 (Northeastern Pacific).

12(1) Fan margin crenulated, not projected posteriorly............................................................ 13

- Fan margin denticulate, medially projected................................................................ 18

13(12) Shield with ribs and concentric lines..................................................................... 14

- Shield with ribs; concentric lines indistinct................................................................ 20

14(13) Shield anterior margins rounded........................................................................ 15

- Shield anterior margins acute........................................... S. spinosa Sluiter, 1882 ( Indonesia, Java).

15(14) Shield with posterior corners distinct..................................................................... 16

- Shield with posterior corners indistinct...................................... S. rietschi Caullery, 1944 ( Indonesia) .

16(15) Posterior corners barely projected beyond fan margin; introvert hooks thick, bronze.......................................................................... S. thalassemoides Otto, 1821 (NE Atlantic Ocean and Mediterranean Sea).

- Posterior corners projected beyond fan margin; introvert hooks thin, golden..................................... 17

17(16) Anterior keels shorter than anterior margins; fan markedly crenulated...................................................................................... S. thorsoni Sendall & Salazar-Vallejo, 2013 (Indian Ocean, Arabian Gulf) .

- Anterior keels as long as anterior margins; fan barely crenulated... S. piotrowskiae Salazar-Vallejo, 2014 ( Philippine Islands)

18(12) Fan without lateral notches; body papillae arranged in distinct transverse rows.................................................................................. S. africana Augener, 1918 (Eastern Atlantic Ocean, Ghana to Angola).

- Fan with lateral notches; body papillae distributed homogeneously, not arranged in transverse rows................... 19

19(18) Introvert with about 15 pale hooks per bundle.................................................................................................... S. andamanensis Sendall & Salazar-Vallejo, 2013 (Indian Ocean, Andaman Sea) .

- Introvert with about 10 dark hooks per bundle....................................................................................................... S. uschakovi Salazar-Vallejo & Buzhinskaja, 2013 (Northern Pacific Ocean)

20(13) Shield with diagonal rib distinct; shield plates as long as wide. S. princeps Selenka, 1885 (SW Pacific Ocean, New Zealand)

- Shield with diagonal rib indistinct; shield plates wider than long..................... S. monroi n. sp. ( Antarctic Ocean)