Atractides nitraensis, Laska, 1959

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 : 298

ATRACTIDES NITRAENSIS LÁSKA, 1959

Syn. to A. oblongus ( Walter, 1944) : syn. nov.

Type series: Lectotype ♂, here designated, MMB Cis. 1528. Atractides nitraensis 1 ♂ 1 ♀; 1329–2 Pramen y ¢ tok Nitry., 19.9.1958 Leg. Láska. State of conservation: good, gnathosoma, both palps and both I-L separate, laterally . Paralectotypes: ♀, together with the lectotype on the same slide and prepared in the same way; ♀ 1329–3, [like lectotype].

Material examined: MMB 1102–1 Tatr. Lomnice potok u Moravy. Tatry. 3.9.1956. Leg. Láska 1 ♀ ; 1108. Ri`cka Bialka na potskè; hranici. Tatry, 4.9.1956 Leg. Láska 1 ♀ ; 1230–2 Ramzovka nad Horni Lipovcu 8.8.1957 Leg. Láska 2 ♂ ; 1454–5 Kaniansk y ¢ pot. Ponitn 17.8.1963 Leg. Láska 1 ♀ (together with A. distans ♀) ; NHMB Prep. 24 29.9.1968 Lelgio Coll. 5¢ 1 ♂ .

Discussion: Láska (1959) compared A. nitraensis in his initial description only with A. protendens , a morphologically very different species with lineated integument, unfused Vgl-1 + 2, and a very stout I-L-6. The specimens of the type series are, however, representatives of the A. spinipes group containing the closely related species A. spinipes and A. oblongus . As these species are minute and have comparatively few morphological particularities, the taxonomic assessment of A. nitraensis requires a presentation of selected measurements and proportions. Measurement values not included within the following survey were found widely overlapping with both species compared.

Males (n = 3): idiosoma L about 450, coxal field L 256–270, Cx-1 mL 106–120, genital field L/W 80/92, palp total L 212–252 Mm; L/H ratio P-2 1.37–1.39, P-3 1.76–1.89, P-4 2.96–3.00; I-L-6 L 94–98 Mm, L/HB 4.70–4.90.

Females (n = 4): idiosoma L 590, coxal field L 165, mL 105–117, palp total L 256–273 Mm; L/H ratio P-2 1.44–1.51, P-3 2.08–2.14, P-4 3.48; setal interspace 10–15 Mm; I-L-6 L 105, L/HB 5.25–6.10.

The only difference with both of the compared species is the slightly increased size of A. nitraensis males (coxal field, Cx-1 mL) and there is no significant diagnostic character restricted to A. nitraensis . A. nitraensis differs from A. spinipes (in parentheses) and corresponds to A. oblongus in the longer median suture of Cx-1 (<100 Mm in both sexes); in males more slender segments P-2 (L/H <1.20) and P-3 (L/ H <1.62) and a relatively stockier P-4 (L/H> 3.10); and in the more slender I-L-6 of females (L/HB <4.9). Furthermore, A. nitraensis agrees with A. oblongus also in the shape of the genital field, in males with the posterior third of the gonopore flanked by the Ac-3, in females with the Ac not in a line, but in a triangular arrangement. The females of A. nitraensis agree with two females in MMB (962–1, 1269–1) labelled as A. longus . Both A. longus and A. nitraensis are synonyms of A. oblongus .

Since the first description, A. nitraensis has been reported only once from Switzerland ( Rensburg, 1971). The specimen in question confirms the proposal of synonymization provided here. As stated correctly by Rensburg, the measurements of the male genital field published by Láska are erroneous, with a margin of error of c. 50%. The female of prep. MMB 1454–5 surely represents a different species, possibly A. nodipalpis . In this specimen, the anterior coxal plate is less slender and with a weakly curved caudal margin of Cx-1, Vgl-1 far apart from Vgl-2, S-2 enlarged, and I-L-6 more slender (L/H 6.5).