Key to deep-water species of Leitoscoloplos from the Eastern Pacific

1A. Branchiae first present from a posterior thoracic setiger....................................................... 2

1B. Branchiae first present from an anterior abdominal setiger..................................................... 3

2A. With 12 thoracic setigers; branchiae from setiger 10; abdominal neuropodium with rounded tip and short ventral cirrus, subpodial flange absent; abdominal notopodia elongate, tapering to narrow tip; branchiae symmetrical, typically triangular, tapering to papillate tip................................................................. Leitoscoloplos sahlingi n. sp.

2B. With 14 thoracic setigers; branchiae from setigers 11–12; abdominal neuropodium with bi-lobed tip; subpodial flange present; abdominal notopodia elongate, with subdistal swelling; branchiae asymmetrical.. Leitoscoloplos mexicanus (Fauchald, 1972)

3A. Pre-setiger region long, narrow, triangular, longer than wide................................................... 4

3B. Pre-setiger region short, as wide as or wider than long........................................................ 5

4A. Furcate setae present; branchiae from setiger 15–16; thoracic noto- and neuropodial postsetal lamellae short, triangular, tapering, arising from low base; abdominal neuropodia without subpodial flange................. Leitoscoloplos cliffordi n. sp.

4B Furcate setae absent; branchiae from setiger 17–18; thoracic noto- and neuropodial postsetal lamellae long, digitiform, arising from broadly rounded base; abdominal neuropodia with protruding subpodial flange....... Leitoscoloplos williamsae n. sp.

5A. Prostomium distinctly separated from peristomium by groove; branchiae elongate, smooth, triangular, tapering to narrow tip ................................................................................................... 6

5B. Prostomium merging posteriorly with peristomium; branchiae short, thick, with glandular appearance........................................................................... Leitoscoloplos pachybranchiatus Blake & Hilbig, 1990

6A Thoracic notopodial postsetal lamellae triangular; abdominal neuropodia with blunt tip with two weakly developed lobes, ventral cirrus absent; subpodial flange absent......................................... Leitoscoloplos gordaensis n. sp.

6B. Thoracic notopodial postsetal lamellae elongate, digitiform, arising from swollen base; abdominal neuropodia with rounded tip and subterminal ventral cirrus; subpodial flange present................................ Leitoscoloplos lunulus n. sp.