Protoribates Berlese, 1908

Walter, David Evans & Latonas, Sarah, 2013, A review of the ecology and distribution of Protoribates (Oribatida, Oripodoidea, Haplozetidae) in Alberta, Canada, with the description of a new species, Zootaxa 3620 (3), pp. 483-499 : 484-485

Genus Protoribates Berlese, 1908

Type species: Oribata dentata Berlese, 1883: 1 .

Diagnosis. Oripodoidea with pteromorphs subtriangular, hinged, movable, and associated with large muscle insertions on notogaster in region of Aa; discidium present as tectum, needle- to blade-like custodium usually present. Sensillus usually reclinate with sublanceolate head, rarely setiform or with erect club-like head. Lamella narrow; sublamella vestigial; prolamella absent; tutorium usually present as ridge; pedotecta I–II small, not visible in dorsal view. Notogaster with octotaxic system composed of porose areas with distinct ring-like rims (in transmitted light), 10 pairs of short to vestigial notogastral setae. Epimeral setation 3-1-3-3; 5 pairs of genital setae; one pair of aggenital setae; 3 pairs of adanal setae. Chelicerae robust, chelate-dentate; palpal solenidion and eupathidium acm form double-horn on short to long apophysis. Tarsi usually monodactyl, less commonly heterotridactyl, rarely bidactyl.

Remarks. The genus Protoribates has had a long and confusing history and finding derived characters supporting this genus is difficult. As Grandjean (1936, 1954) pointed out, the genera of Haplozetidae seem best separated from other Oripodoidea by the desclerotization of the base of the pteromorph (partial in some species) to form a hinge and the development of a tectum near the insertion of legs IV, the discidium, which usually has a well developed cusp or custodium. The hinged pteromorphs can be pulled against the legs by a cluster of enlarged muscles inserted on the notogaster in the region of porose area Aa. Although possibly shared with the Parakalummidae (and apparently convergent with Galumnoidea and some Ceratozetoidea), the movable pteromorphs serve to separate Haplozetidae from other Oripodoidea. The discidium, although again apparently convergent with some distantly related groups (e.g. Oribatellidae ), provides another derived character to support the Haplozetidae . Both Haplozetes and Protoribates share these characters states along with several characters of less clear polarity, e.g. usually 5 pairs of genital setae and 10 pairs of notogastral setae in the adult. The genus Haplozetes is differentiated from Protoribates by having the octotaxic system composed of invaginated saccules rather than flattened porose areas. Species of Peloribates are similarly sacculate, but have 13–14 pairs of welldeveloped notogastral setae. Species of Rostrozetes are similar, but have tubules instead of saccules and 10–11 pairs of notogastral setae.

Pérez-Iñigo (1992), mistakenly believing that Protoribates was an invalid name, proposed a new genus, Transoribates , with Protoribates latus Mihelčič, 1965 , as the type species. This mite has movable pteromorphs, a discidium and notogastral porose areas, but also a sensillus with a short stalk and elongate, spiny club; four pairs of genital setae and a “nose-like” process on the rostrum. Except for the reduction in the number of genital setae and the clubbed sensillus, T. latus resembles Protoribates . The sensillus in the Haplozetidae often has a long stem, reflexed over the notogaster (i.e. reclinate) that may be setiform or end in a sublanceolate to fusiform head of varying lengths, e.g. many species of Haplozetes , Protoribates and Peloribates . However, other species in these genera, e.g. Peloribates juniperi (Ewing, 1913) , Haplozetes cancellatus Beck, 1964 , and Haplozetes clavatus Bayartogtokh, 2000 , have a short, clubbed sensillus and Haplozetes triungulatus Beck, 1964 , has a seemingly intermediate sensillus with a short stem with an elongate, barbed head. The sensillus is also highly variable in species of Rostrozetes , including several with short-stemmed clubs (Beck 1965). Below we describe a new species with the diagnostic characters of Protoribates , but with a sensillus that has a short stem and obovate club. We do not attribute the new species to Transoribates because unlike that genus it has 5 pairs of genital setae and the difference in the form of the sensillus is within the normal range seen in other genera of Haplozetidae .

Depending on the definition used, Protoribates currently contains up to 60 described species with an overall semi-cosmopolitan distribution (Subías 2004). Weigmann et al. (1993) redescribed the type species of the genus, Oribates dentatus Berlese, 1883 ; considered Xylobates Jacot, 1929 a junior synonym; and redefined the genus based on four species: P. dentatus , P. capucinus Berlese, 1908 ; P. lophotrichus (Berlese, 1904) , and P. oblongus (Ewing, 1909) . The diagnosis herein largely follows their concept, but allows for an erect, as well as a reclinate, sensillus. Subías (2004) also lists Alloribates Banks, 1947 ; Propeschelobates Jacot, 1936 ; and Styloribates Jacot, 1929 as junior synonyms of Protoribates .

In their catalogue of North American oribatid mites, Marshall et al. (1987), prior to the clarification of its generic limit, recorded an undetermined species of Protoribates from New York and Qubec and Protoribates sp. nr. langenula (Berlese, 1904) from New Brunswick. They also considered a report of Protoribates monodactylus (Haller, 1884) by Michael (1898) unconfirmed and, based on the study of original specimens, recombined Oribata albida Ewing, 1908 , and Scheloribates albidus (Ewing, 1909) . Therefore, we do not follow Subías (2004) who considered this species a member of Protoribates . Marshall et al. (1987) additionally listed 8 species or subspecies of monodactyl Xylobates from North America. However, after examining type material, Norton and Kethley (1990) determined: (1) that Xylobates oblongus (Ewing, 1909) was distinct from capucinus ; (2) that X. longus (Ewing, 1909) and X. longisetae Jacot, 1937 , were junior synonyms of oblongus ; (3) that X. singularis (Banks, 1947) and X. angustior Jacot, 1937 , were junior synonyms of capucinus . They also raised X. capucinus robustior (Jacot, 1937) to the species level. If we include P. lophotrichus , P. imperfectus (Banks, 1906) , P. prionotus (Woolley, 1968) , and P. dentatus (reported by Subías 2004 to be Holarctic), perhaps seven described species of Protoribates are known from or potentially occur in North America. Below we describe a new species, provide a new diagnosis for P. robustior , confirm the synonymy of P. prionotus with P. lophotrichus , and provide a key for the known species of the genus in North America.