additional source
Sirvid, P.J.;Zhang, Z.; Harvey, M.S.; Rhode, B.E.; Cook, D.R.; Bartsch, I.; Staples, D.A. (2010). Phylum Arthropoda Subphylum Chelicerata: horseshoe crabs, sea spiders, arachnids, in: Gordon, D.P. (Ed.) (2010). New Zealand inventory of biodiversity: 2. Kingdom Animalia: Chaetognatha, Ecdysozoa, Ichnofossils. pp. 50-89. [details]
From editor or global species database
Morphology Ocular-tubercle absent [details]