Atropacarus Ewing

Kamill, B. W. & Baker, A. S., 1980, The genus Atropacarus Ewing (Acari: Cryptostigmata), Bulletin of the British Museum of Natural History (Zoology series) 39, pp. 189-204 : 201-202

[Genus Atropacarus Ewing ]

Survey

In addition to the species referred to above, a number of other taxa, possibly referable to Atropacarus , have been considered but unfortunately type material has not been available in the case of the following six species, all of which fall within the size range given for Atropacarus : illinoisensis (Ewing, 1909), vitrinum , remigerus and somalicus (Berlese, 1913, 1923 & 1923), serratus Feider and Suciu (1957), and collaris Balogh (1958).

In his original description of Atropacarus , Ewing (1917) noted that illinoisensis , of which the type specimen is apparently lost, was 'known to be included in the genus Atropacarus .'' Although from the description and illustration the species does appear to have certain affmities with Atropacarus (sickle-shaped sensillus, stout pectinate notogastral setae, overall length 450 µm), the number and arrangement of setae on the anal plates (two marginal and three submarginal) are reminiscent of Phthiracarus . Moreover, the general shape of the aspis and the form of the integumental ornamentation are characteristic of a Phthiracarus species.

The true identities of the three species described by Berlese are doubtful, although it seems probable that they have been correctly assigned to the genus Steganacarus . Van der Hammen (1959) has examined each of the species which are entire, uncleared and mounted in Canada Balsam, and is of the opinion that they belong to a 'striculus-group'. However, it seems unlikely that they can be reidentified in their present condition.

In their original description of Steganacarus serratus , a species recorded from mosses and leaves, Odorhei, Rumania, Feider and Suciu (1957) described the presence of 14 pairs of notogastral setae. However, it is apparent from their figure that serratus bears at least 16, or possibly even 19 pairs of setae on the notogaster. Unfortunately, there is no information available on the chaetotactic pattern of the legs but it is conceivable that the species may belong to the genus Atropacarus .

Steganacarus collaris , a species described from Angola(Balogh, 1958), cannot be determined as a member of the genus Atropacarus without a re-examination of the holotype for Balogh's description does not include details of any notogastral or leg chaetotactic characters.

The holotype of Steganacarus craterifer , collected by Hammer (1971) from dry leaves on Viti Levu, the Fiji Islands, has been examined. This species is of particular interest for it shares with all species of the genus Atropacarus the presence of a coupled solenidion on tibia IV while only possessing 15 pairs of setae on the notogaster (Hammer figures only 14 pairs). However, the general shape of the aspis and the form of the integumental ornamentation are reminiscent of species of the genus Tropacarus . The arrangement of setae on the genital and anal plates are nevertheless characteristic of Steganacarus .