Genus Dipodarctus Pollock, 1995

Pseudonym with Hemitanarctus de Zio Grimaldi, D’Addabbo Gallo, Morone De Lucia & Troccoli, 1996. Hemitanarctus is the junior synonym because it was published about three months after the name Dipodarctus.

Diagnosis (emended): Dipodarctinae with lanceolate tibia and triangular tarsus of the Tanarctus - type. Digits on the first 3 pairs of legs (I–III) are of different shape than those of fourth leg pair. Three ventral digits are of equal length, claws with calcar and one long dorsal digit with a simple claw. Claws can be covered by a membranous sheath. At the base of the digits, horizontal peduncles are present. Peduncles can be absent in the fourth leg pair in which the two external digits are shorter than the two internal ones. Digits on all legs can be simple or with jointlike folds. Digits with parallel folds or spiraled digits. Cephalic appendages are long primary and indistinct secondary clavae, a robust medial cirrus, external, internal and lateral cirri. The cirri may consist of three segments (cirrophorus, scapus and flagellum). Sense organs on the first three pairs of legs can be simple or more complex, formed by a more or less visible cirrophorus, a scapus and a flagellum. The sense organ of the fourth leg pair consist of ovoid papilla or the elongated Halechiniscus - type papilla with a terminal spine. Pharyngeal bulb is of variable size with straight to horn-shaped placoids. Body is with or without Halechiniscus - type lateral processes. The ducts of seminal receptacles open laterally and close to the insertion of the coxa of leg IV.

Type-species: Dipodarctus borrori Pollock, 1995.

Junior synonym: Hemitanarctus chimaera de Zio Grimaldi, D’Addabbo Gallo, Morone De Lucia & Troccoli, 1996.

Additional species: Dipodarctus anaholiensis Pollock, 1995; Dipodarctus subterraneus (Renaud-Debyser, 1959)

Remarks. The genus Dipodarctus was described by Pollock (1995) from shallow water sediment samples from the Hawaiian Islands. Pollock (1995) stated that the two new Hawaiian species D. borror i and D. anaholiensis possessed features so unique as to constitute a new genus and to require the erection of a new subfamily, Dipodarctinae. What Pollock overlooked was that this type of halechiniscid tardigrade was already described by Renaud-Debyser (1959) from the intertidal zone of Bimini Island (Bahamas). She based the description of her species, Halechinsicus subterraneus Renaud-Debyser, 1959, on only two males, and she proposed that the extra long primary clavae could be a male secondary sexual characteristic.

A few months after Pollock’s description (1995) of Dipodarctus, de Zio Grimaldi et al. (1995 /96) described the same genus in intertidal, coarse sand from Tananto (Italy). They established the new genus Hemitanarctus, based on H. chimaera. In the same article they included Halechiniscus subterranus in the new genus. The species Hemitanarctus subterraneus (Renaud-Debyser, 1959) was redescribed based on material from the Mediterranean Sea and the Atlantic Ocean. The genus Hemitanarctus must be considered as a junior synonym of the genus Dipodarctus.

The two new species of dipodarctinae found in the marine caves of Australia clearly belong to the genus Dipodarctus.