Hesionidae, Grube, 1850

Hiro, Uchida, omi, Lopéz, Eduardo & Sato, Masanori, 2019, New Hesionidae (Annelida) from Japan: Unavailable Names Introduced by Uchida (2004) Revisited, with Reestablishment of their Availability, Species Diversity 24, pp. 69-95 : 91-93

Key to species of Hesionidae recorded from Japan

1 Two pairs of tentacular cirri; prostomium completely embedded into peristomium............................................. Ichthyohesione gorgasiae sp. nov.

— Three or more pairs of tentacular cirri; prostomium partially fused to peristomium or clearly distinct......... 2

2 With three pairs of tentacular cirri (Genus Hesionides Friedrich, 1937 ).................................. 3

— With four or more pairs of tentacular cirri........... 7

3 Posterior end consisting in two clearly separated anal lamellae.......................................... 4

— Posterior end consisting in a single anal membrane.... 5

4 Anal lamellae rectangular; longest notochaetae extending beyond notocirrus tip and with 5–8 teeth..................... Hesionides minima serrata Yamanishi, 1984

— Anal lamellae rounded and fan shaped; longest notochaetae shorter than notocirri and with 4–7 teeth........................ Hesionides arenaria Friedrich, 1937

5 Anal membrane triangular, with posterior end incised..................... Hesionides incisa Yamanishi, 1984

— Anal membrane rounded and fan-shaped, with posterior end entire....................................... 6

6 Notopodia from chaetiger 4 onwards supported by a distinctly thick acicula; longest notochaetae with 3 or 4 teeth... Hesionides indoceanica Westheide and Rao, 1977

— All notopodial aciculae uniformly thin; longest notochaetae with about 20 teeth............................... Hesionides unilamellata japonica Yamanishi, 1984

7 With four pairs of tentacular cirri......................................... Parahesiocaeca japonica sp. nov.

— With six or more pairs of tentacular cirri............. 8

8 With six pairs of tentacular cirri.................... 9

— With eight pairs of tentacular cirri................. 25

9 First chaetiger uniramous and bearing a modified clawshaped compound chaeta................................................ Uncopodarke intermedia sp. nov.

— First chaetiger similar to following ones and lacking modified compound chaetae...................... 10

10 Prostomium with median antenna................. 11

— Prostomium without median antenna.............. 23

11 Palps not articulate.............................. 12

— Palps biarticulate (Genus Oxydromus Grube, 1955 )... 14

12 Midbody chaetigers bearing modified falciger neurochaetae with very short, conical blades....................................... Heteropodarke kiiensis sp. nov.

— Neourochaetae in midbody chaetiges similar to the remaining ones; posterior end bearing an expanded anal membrane (Genus Microphthalmus Mecznikow, 1865 ).. ............................................... 13

13 Simple neurochaetae bidentate; compound neurochaetae with blades uniformly short, strongly bidentate and weakly serrated................................................ Microphtalmus japonicus Yamanishi, 1984

— Simple neurochaetae unidentate; compound neurochaetae with two kinds of blades (long and short), some long blades with coarse serration and rounded tip................................... Microphthalmus itoi sp. nov.

14 Neuropodial lobes short and very stout..................................... Oxydromus brevipodius sp. nov.

— Neuropodial lobes well projecting from body sides... 15

15 Notopodial cirrophores as long as the corresponding neuropodial lobe or only slightly shorter............ 16

— Notopodial cirrophores clearly shorter than the corresponding neuropodial lobe....................... 19

16 Notopodial cirrophores with a clear constriction and reduced diameter in distal section; neuropodial prechaetal lobes triangular................................. 17

— Constriction of notopodial cirrophores absent or not causing diameter reduction; neuropodial prechaetal lobes cylindrical with rounded apex.......................................... Oxydromus bunbuku sp. nov.

17 Constriction of notopodial cirrophores located near distal end............. Oxydromus berrisfordi ( Day, 1967)

— Constriction of notopodial cirrophores at 1/3 of total length from distal end............................ 18

18 Width of notopodial cirrophores gradually reducing from constriction; inner part of compound chaeta joints straight in side view............................................... Oxydromus angustifrons ( Grube, 1878)

— Width of notopodial cirrophores abruptly reducing from constriction; inner part of compound chaeta joints un- dulate in side view....................................................... Oxydromus constrictus sp. nov.

19 Notopodial cirrophores with a clear constriction and reduced diameter in distal section.......................................... Oxydromus parapallidus sp. nov.

— Constriction of notopodial cirrophores absent or not causing diameter reduction....................... 20

20 Constriction of notopodial cirrophores inconspicuous; basal article of palps longer than distal one................................. Oxydromus longifundus sp. nov.

— Constriction of notopodial cirrophores absent; basal article of palps shorter than distal one................ 21

21 Body without dorsal white bands................................... Oxydromus pugettensis ( Johnson, 1901)

— Body with dorsal white bands..................... 22

22 Shaft of compound chaetae with bifid tips; dorsal white bands on chaetigers 2, 8, 12, 17, 21, 27, 31, 35, 39, and 43.......................... Oxydromus okudai sp. nov.

— Shaft of compound chaetae with acute tips; dorsal white bands on chaetigers 2, 8, 12, 17, 21, 25, 29, 33, 35, 39, and 43.................... Oxydromus fauveli sp. nov.

23 Pharynx bearing a pair of conspicuous chitinous jaws...................... Syllidia armata Quatrefages, 1866

— Pharynx without noticeable jaws................... 24

24 With simple, subconical neuropodial lobes bearing an acicular neurochaeta...... Synsyllidia alternata sp. nov.

— Neuropodia lobes cylindrical and distally bilobed, acicular neurochaetae absent............................................... Micropodarke dubia ( Hessle, 1925)

25 Median antenna lacking.......................... 26

— Median antenna present.......................... 33

26 Parapodia biramous.. Hesiospina aurantiaca ( Sars, 1862)

— Parapodia sub-biramous.......................... 27

27 Non-articulate palps present..................................... Elisesione imajimai Jimi, Eibye-Jacobsen, and Salazar-Vallejo, 2018

— Palps absent (Genus Hesione Lamarck, 1818 )........ 28

28 Neuroaciculae colorless.............................................. Hesione horsti Salazar-Vallejo, 2018

— Neuroaciulae blackish............................ 29

29 Parapodia with single acicular lobe................. 30

— Parapodia with bifid acicular lobe.................. 31

30 Blades of compound neurochaetae 3–4 times as long as wide.................. Hesione intertexta Grube, 1878

— Blades of compound neurochaetae up to 6 times as long as wide........... Hesione uchidai Salazar-Vallejo, 2018

31 Subdistal tooth similar in size to distal one.................................... Hesione genetta Grube, 1867

— Subdistal tooth clearly smaller than distal one....... 32

32 Blades of compound neurochaetae bearing a subdistal guard............ Hesione reticulata Marenzeller, 1879

— Blades of compound neurochaetae lacking subdistal guard............ Hesione keablei Salazar-Vallejo, 2018

33 Pharynx with a pair of horny teeth................. 34

— Pharynx without hard teeth or jaws................ 38

34 Notochaetae present (Genus Leocrates Kinberg, 1866 ).. ............................................... 35

— Notochaetae absent (Genus Leocratides Ehlers, 1908 )... ............................................... 36

35 Ventral cirri long, approximately twice as long as the corresponding neuropodial lobe............................................ Leocrates auritus Hessle, 1925

— Ventral cirri short, similar in length to the corresponding neuropodial lobe................................................... Leocrates chinensis Kinberg, 1866

36 Lateral antennas long as the palps.................................... Leocratides kimuraorum Jimi, Tanaka, and Kajihara, 2017

— Lateral antennae shorter than the palps............. 37

37 Pharyngeal terminal papillae and papillose peristomial membrane absent...... Leocratides ehlersi (Horst, 1921)

— Pharyngeal terminal papillae and papillose peristomial membrane absent................................................... Leocratides filamentosus Ehlers, 1908

38 Parapodia without notochaetae; distal edge of pharynx smooth...... Amphiduros fuscescens ( Marenzeller, 1879)

— Parapodia with notochaetae; pharynx with a distal rim of papillae...................................... 39

39 Nuchal organ dorsally coalescent; median antenna different in shape to lateral ones (Genus Gyptis Marion, 1874 ).......................................... 40

— Nuchal organ mid-dorsally separated; median antenna similar in shape to lateral ones (Genus Podarkeopsis Laubier, 1961 )................................... 41

40 Nuchal organs as well developed lappets; ventral cirri clearly longer than corresponding neuropodial lobe............................ Gyptis lobatus ( Hessle, 1925)

— Nuchal organs a continuous ridge; ventral cirri similar in length to corresponding neuropodial lobe................................. Gyptis pacificus ( Hessle, 1925)

41 Furcate neurochaetae with smooth shaft................. Podarkeopsis brevipalpa ( Hartmann-Schröder, 1959)

— Furcate neurochaetae with denticulate shaft........................... Podarkeopsis glabrus (Hartman, 1961)