Table 2.

Comparison of anatomical features of species of Arachnanthus (after Carlgren 1912b; Carlgren 1924; Carlgren 1937; Picton and Manuel 1985; this study).

	A. australiae	A. bockii	A. oligopodus	A. sarsi	A. lilith sp. n.
Marginal tentacles	Up to 40	Up to 30	~20	Up to 35	Up to 24
Arrangement of labial tentacles	(0)1.11.11.11.11	(0)1.11.11.11.11(?)	(0)1.11.11.11.11	(0)1.11.11.11.11	(0)3.12.31.23.23.12
Length of actinopharynx	~2/3 of gastric cavity	~1/2 of gastric cavity	~1/2 of gastric cavity	~1/2 of gastric cavity	>1/2 of gastric cavity
Hyposulcus	~1/2 size of stomodeum	~1/2 size of stomodeum	~2X size of stomodeum	< size of stomodeum	= size of stomodeum
Oral disc diameter	~0.7 cm	–	–	~1 cm	0.5 cm
Maximum n° of mesentery attached to siphonoglyph	12	12	4	6	8
Directive mesenteries	= length of Actinopharynx	< length of Actinopharynx	> length of Actinopharynx	< length of Actinopharynx	< length of Actinopharynx
P(C)2	Short, 1/2 of gastric cavity	Very short, 1/4 of gastric cavity	Short, 1/2 of gastric cavity	Long, 3/4 of gastric cavity	Long, 6/7 of gastric cavity, almost to aboral pole
P(C)3	Very short, <1/4 of gastric cavity	Very short, <1/4 of gastric cavity	Short, ~1/2 of gastric cavity	Short, ~1/3 of gastric cavity	Short, 1/3 of gastric cavity
M1	Almost to aboral pore	Almost to aboral pore	To aboral pore	Almost to aboral pore	To aboral pore
M3	4/5 of gastric cavity	Almost to aboral pore	1/5 of gastric cavity	Almost to aboral pore	3/4 of gastric cavity
Cnido-glandular tract of fertile mesenteries	Present (short?)	Present (short?)	Present	Present	Present
Cnido-glandular tract of B	Present (short?)	Present (short?)	Present (short?)	Present (short)	Present (short)
Acontioids	Only in M1, M2 and M3	Only in M1, M2 and M3	Only in M1	Only in M1, M2 and M3	Only in M3 and M4
Distribution	Northern Australia	Fiji	Mediterranean Sea	North Sea	Red Sea