Key to species of Nephtyidae (modified from Rizzo & Amaral 2007) from Brazil

1a Interramal branchiae curved inward and antennae present........................................ Aglaophamus …2

1b Interramal branchiae curved inward and antennae absent....................................... Inermonephtys …6

1c Interramal branchiae curved outward and antennae present.......................................... Nephtys …8*

2a(1a) Interramal branchiae starting from parapodium 4 or 4−5; proboscis with fewer than 20 rows of subdistal papillae........ 3

2b(1a) Interramal branchiae starting from parapodium 3 or 3−4; proboscis with 20 or more rows of subdistal papillae..........4

3a(2a) Interramal branchiae starting from parapodium 4; proboscis with 20 paired distal papillae, 16 rows of 4-6 subdistal papillae, and a long unpaired middorsal papilla.............................................. A. juvenalis (Kinberg, 1866)

3b(2a) Interramal branchiae starting from parapodium 4−5; proboscis with 22 paired distal papillae, 14 rows of 7–8 subdistal papil- lae, and a long unpaired middorsal papilla........................................... A. dibranchis (Grube, 1877)

4a(2b) Interramal branchiae starting from parapodium 3; proboscis with 20 rows of 3-5 subdistal papillae, without unpaired median papilla............................................................................... A. fabrun sp. nov.

4b(2b) Proboscis with short unpaired middorsal and midventral papillae, or with only an unpaired middorsal papilla...........5

5a(4b) Interramal branchiae starting from parapodium 4; proboscis with 20 paired distal papillae, 20 rows of 6-9 subdistal papillae, and an unpaired middorsal papilla.................................................. A. uruguayi Hartman, 1953

5b(4b) Interramal branchiae starting from parapodium 3−4; proboscis with 20 paired distal papillae, 22 rows of 2-3 subdistal papil- lae, and a short unpaired middorsal and midventral papilla............................ A. macroura (Schmarda, 1861)

6a(1b) Prostomium without eyes..............................................................................7

6b(1b) Prostomium with two pairs of dark eyes.............................................. .. I. inermis (Ehlers, 1887)

7a(6a) Branchiae starting from parapodium 5, with basal papillae starting on chaetiger 6; prostomium with a slight central dorsal depression............................................................................. I. soldius sp. nov.

7b(6a) Branchiae starting from parapodium 3, with basal papillae starting on chaetiger 5; prostomium nearly pentagonal, without a central dorsal depression............................................... I. brasiliensis (Martin, Gil & Lana, 2009)

8a(1c) Interramal branchiae starting before parapodium 6..........................................................9

8b(1c) Interramal branchiae starting from parapodium 8 or more.................................................... 14

9a(8a) Prostomial central region with characteristic pigmentation pattern (present even in specimens conserved in ethanol for a long period)............................................................................................ 10

9b(8a) Prostomial central region without characteristic pigmentation pattern..........................................11 10a(9a) Proboscis with 23 conical distal papillae and long middorsal and midventral subdistal papillae..... N. simoni Perkins, 1980 10b(9a) Interramal branchiae starting from parapodium 3; proboscis with 22 conical distal papillae and long middorsal subdistal

papilla....................................................................... N. magellanica Augener, 1912 10c(9a) Interramal branchiae starting from parapodium 3−4; proboscis with 21 conical distal papillae and without long middorsal or

midventral subdistal papilla.................................................. .. N. californiensis Hartman, 1938 11a(9b) Proboscis with long middorsal subdistal papilla...........................................................12 11b(9b) Proboscis without long middorsal subdistal papilla; interramal branchiae starting from parapodium 4−6, usually 4........

.............................................................................. N. caeca (Fabricius, 1780) 12a(11a) Proboscis with long midventral subdistal papilla; spur-like chaetae present; interramal branchiae starting from parapodium

1−4, usually 3................................................................... N. squamosa Ehlers, 1887 12b(11a) Proboscis without long midventral subdistal papilla; spur-like chaetae absent.................................... 13 13a(12b) Interramal branchiae starting from parapodium 4−6, usually 5 (nearly disappearing at end of body); acicular lobes with

prominent medial bulb or papilla......................................... N. hombergi Savigny in Lamarck, 1818 13b(12b) Interramal branchiae starting from parapodium 5 (disappearing after 36th); acicular lobes without prominent medial bulb or

papilla......................................................................... N. fluviatilis Monro, 1937 14b(8b) Spur-like chaetae absent............................................................ N. paradoxa Malm, 1874 14a(8b) Spur-like chaetae present...................................................... .. N. acrochaeta Hartman, 1950 * Although Nephthys laciniosa was originally described from Rio de Janeiro (Brazil) by Grube (1881), the type material seems to be

lost. This species is known only from the type locality. For this reason, it was not included in the key.