Development of a lecithotrophic pilidium larva illustrates convergent evolution of trochophore-like morphology

Table 2 Comparison of juvenile rudiment development in several lecithotrophic and one planktotrophic pilidium.

	Rudiments reported as imaginal discs	Other reported juvenile rudiments	Rudiments reported with uncertain origin	invaginating rudiments	Total # of juvenile rudiments	Source
Micrura akkeshiensis	5	3		7	8
Micrura akkeshiensis	Paired cd and td. Unpaired dd	Paired cor. Unpaired pb		Paired cd, td and cod. Unpaired dd		Iwata 1958 [12]
Lineus ruber	4	1	3	4	5–8
	Paired cd and td	Unpaired pb	Paired cod. Unpaired pb	Paired cd and td		Martîn-Durán et al. 2015 [17]
	8			4	8
	Paired cd, td, and cod. Unpaired dr and pb			Paired cd and td		Schmidt 1964 [68]
Micrura rubramaculosa	5			?	5	Schwartz and Norenburg 2005 [23]
Micrura verrilli	5			?	5	Schwartz 2009 [15]
Micrura sp. 803	6			?	6	Schwartz 2009 [15]
Micrura sp. “dark”	6	2		6	8
Micrura sp. “dark”	Paired cd, td and cod	Unpaired pb and dr		Paired cd, td and cod		This study
Maculaura alaskensis ^a	6	2		6	8
Maculaura alaskensis ^a	Paired cd, td and cod	Unpaired pb and dr		Paired cd, td and cod		Maslakova 2010 [10]

The first four columns describe juvenile rudiment development reported in the literature. The fifth column identifies which rudiments were reported to invaginate (and/or shown to invaginate in figures). The final column gives the total number of juvenile rudiments. cd—cephalic, discs td—trunk discs, dd—dorsal disc, cor—cerebral organ rudiments, pb—proboscis rudiment, cod—cerebral organ discs, dr—dorsal rudiment. ^aMaculaura alaskensis bears a typical planktotrophic pilidium and is included for comparison

ISSN: 1742-9994