Archeterokrohnia docrickettsae (Chaetognatha: Phragmophora: Heterokrohniidae), a new species of deep-sea arrow worm from the Gulf of California Author Thuesen, Erik V. Author Haddock, Steven H. D. text Zootaxa 2013 3717 3 320 328 journal article 10.11646/zootaxa.3717.3.2 165ed40d-f5f4-4a37-9c80-9ebf7e049454 1175-5326 222006 9C7F8EF8-E7C7-4D56-9CDF-7977FDF9C4B3 Key to the four species of Archeterokrohnia 1 Tail section ~50% total length, lateral fins beginning halfway between trunk-tail septum and ventral ganglion, ventral ganglion centered 2/3 distance from head to trunk-tail septum, corona ciliata shaped like an outside caliper, fins rayless........................................................................................... A. rubra Casanova, 1986 a - Tail section ~55% of total length, lateral fins with rays and beginning at or near trunk-tail septum..................... 2 2 Head trapezoidal, anterior teeth replaced with plates bearing denticles, pair of palps with teeth-like processes located below vestibular organ................................................................ A. palpifera Casanova, 1986 b - Head triangular, both anterior and posterior teeth, well-developed vestibular organs................................. 3 3 Total length 12.9 mm , 6–8 anterior teeth, 1 posterior tooth, no vestibular plates or palps, head with apical gland-cell complex, triangular process on head absent.......................................... A. longicaudata (Hagen & Kapp, 1986) - Total length 28.5 mm , 10–11 anterior teeth, 4 posterior teeth clustered below a vestibular plate bearing denticles, ventral ganglion slightly posterior to midpoint between head and trunk-tail septum, anterior of head with a triangular process............................................................................................. A. docrickettsae n. sp.