1H): V-shaped, open posteriorly and closed anteriorly; palidia monostichous
, with each palidium consisting of a row of 7 or 8 small size with flattened apex pali; septula elongate, length 3* its width at posterior end; lower anal lip with moderate amount of short and medium size setae and few long setae proximal to anal aperture.
Terms used here are listed alphabetically outside the parentheses; those within parentheses are alternatives found in the literature: copulatory spicules (copulatory stylets); epidermal sclerites (spicules); lower gametoducts (spawning ducts, shell gland); mantle cavity (pallial cavity); monostichous radula (monoserial) [one tooth per row]; radula sac (radula sheath); upper gametoducts (pericardioducts); vestibule, vestibular (atrium, atrial); ventrolateral pharyngeal foregut glands (ventral salivary glands).
Dondersiidae comprises nine genera and 32 species (Table 1) on the basis of a thin cuticle without skeletal sclerites or epidermal papillae (not unique to this family), and by varying combinations of characters: body with or without posterior end drawn out into fingerlike projection; with two or more types of raised (not adpressed) solid sclerites or one type of adpressed scales; radula monostichous with two or more denticles per row, the central two fused or not fused distally, or radula lacking; ventrolateral foregut glands as groups of extraepithelial unicellular gland cells ("follicles") or as multicellular glands ("type A"); and with or without copulatory spicules.
The fused, single duct that joins the ducts of the paired ventrolateral foregut glands in Dondersia is found in other Solenogastres genera with monostichous and polystichous radulae (Nierstrasz, 1905; Scheltema et al., 2003) and is thus not unique to the Dondersiidae.
Radula monostichous with four denticles, the medial pair fused and two laterals out-swung; paired copulatory spicules with sharp bend and two processes lying in short sac, mostly extended into mantle cavity; foot with two folds anteriorly, becoming single, stout fold, reaching onto posteroventral body lobe; suprapallial glands present; with a retractile patch of specialized epidermis anterior to the dorsoterminal sense organ (Salvini-Plawen, 1978, fig.
11B, 21A), one tooth per row (monostichous) (e.g., Acanthomenia, see Scheltema, 1999b, fig.
A single species in each of the 5 genera described here, plus a species with a monostichous radula, Lyratoherpia incali Scheltema (1999b), were the subjects of a cladistic analysis.