Atractides elongatus, (HALBERT, 1944)

Gerecke, Reinhard, 2003, Water mites of the genus Atractides Koch, 1837 (Acari: Parasitengona: Hygrobatidae) in the western Palaearctic region: a revision, Zoological Journal of the Linnean Society 138, pp. 141-378 : 339

ATRACTIDES ELONGATUS ( HALBERT, 1944)

Megapus elongatus Halbert, 1944

syn. to A. lacustris ( Lundblad, 1925) ?: ( Lundblad, 1962b); rejected synonymy

Species dubia: Gledhill & K. O. Viets, 1976

Syn. to A. acutirostris Motaş & Angelier, 1927 : syn. nov.

Type series: Holotype ♀, MNHD ♀ Type Megapus elongatus n. sp. Halb. Type Straffan R. Liffey L. 51 ( IV) J.N. H. (transferred to glycerine jelly January 82 T. Gledhill). State of conservation: coxal area heavily damaged, longitudinally broken, all legs separate, mostly single segments remaining, only one I-L-4/5 preserved, but lacking S-1 and -2, gnathosomal base and chelicera lacking, both palps lacking P-1. Halbert knew of more than one specimen from the collecting site, but this is no longer available ( Gledhill, 1986a).

Discussion: Halbert considered this species to be similar to A. pavesii and A. spinirostris , mainly on the basis of age-dependent characters such as shape of idiosoma, extension of coxae, and relative position of genital field and excretory pore. He overlooked the presence of ‘cheeks’ on P-5 and considered their absence as distinctive. Instead, judging from his figure 22b, A. elongatus differs from A. pavesii in having a narrower setal interspace on I-L-5 and smaller palp dimensions (L/H P-2 78/45, P-3 96/36, P-4 112/31, P-5 34/13 Mm). The presence of a dorsal leg clawlet (as given in Halbert’s fig. 22b) cannot be confirmed from the remnants of the preparation. Probably, the figure represents the tip of the second claw.

Lundblad’s suggestion that A. elongatus might be a synonym of A. lacustris was based on Halbert’s erroneous statement concerning the absence of ‘cheeks’ on P-5 and must be rejected. A. lacustris differs also in the enlarged sword seta on P-4 and wider setal interspace. Gledhill (1986a,b) provided detailed redescriptions for this and the following two species published from Ireland, and considered them species dubiae. The holotype (and only available specimen) is badly damaged, and the original description is scanty. In the arrangement of S-1 and -2 it agrees with A. acutirostris , and as far as measurements can be taken, they lie within, or close to, the variability range of that species. As the presence of A. acutirostris in Ireland is now confirmed by additional collections, there is good reason to consider A. elongatus its junior synonym.