TABLE 2. Comparison of the characters of the Polyzoniida and Siphonocryptida families, based on own observations and the literature (Hoffman 1982; Enghoff & Golovatch 1995; Enghoff et al. 2015).

ORDER		Polyzoniida		Siphonocryptida
FAMILY	Hirudisomatidae	Polyzoniidae	Siphonotidae	Siphonocryptidae
Posterior tergal margin	upturned	not upturned	not upturned	upturned (in Hirudicryptus)
Row of tubercles on tergites	absent	absent	absent	present
Ozopore position	close to lateral tergal margin	at some distance from lateral tergal margin	at some distance from lateral tergal margin	on peritremata on tergal margin
Paronychium	present	absent	present	absent
Posterior tergal margin of last tergite, shape	straight	straight	rounded	straight
Telson	covered by tergite	partially covered by tergite	partially covered by tergite	covered by tergite
Preanal ring	completely fused	ventrally divided	completely fused	ventrally divided
Antennomeres	elongated	elongated	stout	stout
Male, gonopores	opening through 2nd coxae	opening through intersegmental membrane behind 2nd coxae	opening through 2nd coxae	opening through 2nd coxae