Megalomma Johansson, 1925 (Polychaeta: Sabellidae) from America and other world-wide localities, and phylogenetic relationships within the genus 2861 Author Tovar-Hernández, María Ana Author Carrera-Parra, Luis F. text Zootaxa 2011 2011-04-29 2861 1 1 71 https://biotaxa.org/Zootaxa/article/view/zootaxa.2861.1.1 journal article 10.11646/zootaxa.2861.1.1 1175­5334 5286352 Key to American species of Megalomma 1 Radiolar eyes present only in dorsalmost radioles........................................................... 2 - Radiolar eyes not only in dorsalmost radioles............................................................... 5 2(1) Dorsal collar margins fused to faecal groove ( Fig. 1A ); anterior peristomial ring not exposed ( Fig. 17A, D )...................................................................................... M. modestum ( de Quatrefages, 1866 ) - Dorsal collar margins not fused to faecal groove ( Figs 1D , 22E ); anterior peristomial ring exposed ( Figs 1D , 3A , 12A , 22E ). ................................................................................................... 3 3(2) Ventral shield of collar divided transversally in two parts ( Fig. 23D, G ); with caruncle ( Fig. 23H )...................................................................................................... M. pigmentum Reish, 1963 - Ventral shield of collar entire ( Fig. 5C ); caruncle absent....................................................... 4 4(3) Anterior peristomial ring exposed dorsally ( Figs 3A , 5A ); ventral basal flanges absent; inferior thoracic chaetae type B ( Fig. 5G ).......................................................................... M. bioculatum ( Ehlers, 1887 ) - Anterior peristomial ring exposed dorsally and laterally ( Figs 12A–C , 13A–B, D ); ventral basal flanges present ( Fig. 13D ); inferior thoracic chaetae type C ( Fig. 1G )............................................ M. gesae Knight-Jones, 1997 5(1) Eyes distributed only in 2–7 pairs of radioles............................................................... 6 - Eyes distributed in most radioles........................................................................ 8 6(5) Spiraled eyes ( Figs 24G–I , 25F–H ); dorsal collar margins rounded posteriorly, showing the anterior peristomial ring partially ( Fig. 24B )................................................................... M. splendidum ( Moore, 1905 ) - Spherical eyes ( Figs 7G–H , 11E–F )...................................................................... 7 7(6) Dorsal lappets present ( Fig. 11A ); eyes in seven pairs of radioles (dorsalmost and lateral radioles) ( Fig. 7G–H ).................................................................................... M. fauchaldi Giangrande et al . 2007 - Dorsal lappets absent ( Fig. 7C ); eyes in two pairs of radioles (dorsalmost and fifth dorsal radioles); with a glandular ring on chaetiger 3 ( Fig. 7C )........................................................ M. coloratum ( Chamberlin, 1919 ) 8(5) Dorsal margins of collar not fused to faecal groove ( Fig. 1D ); anterior peristomial ring exposed dorsally; ocular spots in ventralmost radioles ( Fig. 26G )............................................................. M. georgiense n. sp. - Dorsal margin of collar fused to faecal groove ( Figs 1A , 16A ); anterior peristomial ring not exposed.................... 9 9(8) With dorsal lappets ( Fig. 21A ); inferior thoracic chaetae type A ( Fig. 1E ).................................................................................................. M. perkinsi Tovar-Hernández and Salazar-Vallejo, 2006 - Dorsal lappets absent ( Fig. 16A ); inferior thoracic chaetae types B ( Fig. 1F ) or C ( Fig. 1G )......................... 10 10(9) With caruncle; interramal eyespots present in thorax and abdomen; inferior thoracic chaetae type B................... 11 - Caruncle absent; interramal eyespots absent; inferior thoracic chaetae type C..................................... 12 11(10) Dorsal collar margins rounded posteriorly, showing partially the anterior peristomial ring.................................................................................. M. carunculata Tovar-Hernández and Salazar-Vallejo, 2008 - Dorsal collar margins level, covering the anterior peristomial ring ( Fig. 16A )................ M. lobiferum ( Ehlers, 1887 ) 12(10) Thoracic tori contacting ventral shields ( Fig. 19C ); ventral sacs and dorsal pockets present ( Fig. 19B )................................................................................................... M. pacifici ( Grube, 1859 ) - Thoracic tori separated from ventral shields ( Figs 4B , 14C )................................................... 13 13(12) Radioles and anterior thorax with scattered dark spots ( Fig. 14C, E–F ); ventral sacs absent....... M. heterops Perkins, 1984 - Radioles and anterior thorax without scattered dark spots; ventral sacs present ( Fig. 4D ).. M. circumspectum ( Moore, 1923 )