Ancistrosyllis McIntosh, 1878

Plathong, Jintana, Dean, Harlan K. & Plathong, Sakanan, 2021, Four new species of Pilargidae (Annelida: Pilarginae) from the Gulf of Thailand, Zootaxa 5071 (4), pp. 537-562 : 539

Key to the species of Ancistrosyllis McIntosh, 1878

1A Prostomium with only a median antenna with two pairs of eyespots and one pair of small, subulate tentacular cirri........................................................................... A. quellina Wesenberg-Lund, 1962 ; Chile, SE Pacific

1B Prostomium with both a median antenna and two lateral antennae............................................ 2

1C Prostomium with two lateral antennae, median antenna absent............................................... 9

2A(1B) Eyespots present, one pair............................................................................ 3

2B(1B) Eyespots absent.................................................................................... 4

3A(2A) Two pairs of short, subequal tentacular cirri; dorsal cirri from chaetiger 1 and ventral cirri from chaetiger 3; first notopodial hooks from chaetiger 3...................................................... A. hartmanae Pettibone, 1966 ; Chesapeake Bay to Gulf of Mexico, Western Atlantic

3B(2A) Two pairs of tentacular cirri, both dorsal and ventral cirri from chaetiger 1; first notopodial hooks from chaetiger 5............................................................................... A. cingulata Korschelt, 1893 ; Adriatic Sea

4A(2B) First notopodial hooks from chaetiger 3................................................................. 5

4B(2B) First notopodial hooks from other chaetigers............................................................. 6

5A(4A) Dorsal and ventral cirri from chaetiger 1; neurochaetae 2 types, bifid tips.................... A. nakkaritae sp. nov.; Gulf of Thailand, Western Pacific

5B(4A) Dorsal cirri from chaetiger 1; ventral cirri from chaetiger 2................... A. fioronii Fiege & Böggemann, 1999 ; North Sea, Atlantic Ocean

5C(4A) Dorsal cirri from chaetiger 1; ventral cirri from chaetiger 3; neurochaetae 2 types unidentate tips.................................................................................................. A. kornkanokae sp. nov.; Gulf of Thailand, Western Pacific

6A(4B) Dorsal and ventral cirri from chaetiger 1................................................................ 7

6B(4B) Dorsal cirri from chaetiger 1; ventral cirri from chaetiger 3, first notopodial hooks from chaetiger 6.............................................................................................. A. jonesi Pettibone, 1966 ; Maryland, Atlantic Ocean

7A(6A) First notopodial hooks from chaetiger 4–6............................................................... 8

7B(6A) First notopodial hooks from chaetiger 13......................................... A. breviceps Hartman, 1963 ; Southern California, Pacific Ocean

8A(7A) First dorsal cirri twice as long as following ones............................... A. groenlandica McIntosh, 1878 ; off Greenland, Arctic Ocean

8B(7A) First notopodial hooks from chaetiger 6....................................... A. commensalis Gardiner, 1976 ; North Carolina, Atlantic Ocean

9A(1C) Eyespots present.................................................................................. 10

9B(1C) Eyespots absent................................................................................... 11

10A(9A) First notopodial hooks from chaetiger 3............................................. A. papillosa Jones, 1961 ; USA coast of Gulf of Mexico

10B(9A) First notopodial hooks from chaetiger 7................................................ A. falcata Day, 1957 ; South Africa

11A(9B) Ventral cirri from chaetiger 2........................................................................ 12

11B(9B) Ventral cirri from chaetiger 3; notopodial hooks from chaetigers 4–7..................... A. hamata Hartman, 1960 ; Southern California, Pacific Ocean

12A(11A) Notopodial hooks from chaetiger 6........................................... A. carolinensis Gardiner, 1976 ; North Carolina to the Gulf of Mexico, Western Atlantic

12B(11A) Notopodial hooks from chaetiger 7........................................ A. matlaensis Mandal & Deb, 2018 ; Estuarine System, India, Indian Ocean